26. July 2010 by admin.

The P53 protein provides a first line of defense against cancers, causing cancer cells to commit apoptosis.  “p53 (also known as protein 53 or tumor protein 53), is a tumor suppressor protein that in humans is encoded by the TP53 gene.^[1][2][3] p53 is important in multicellular organisms, where it regulates the cell cycle and, thus, functions as a tumor suppressor that is involved in preventing cancer. As such, p53 has been described as “the guardian of the genome“, the “guardian angel gene”, and the “master watchman”, referring to its role in conserving stability by preventing genome mutation^[4](ref). ”  However, the guardian angel can’t do its job if is mutated in the cancer or if the cancer has evolved a method to turn it off - which is the case in about 50% of cancer types, those having “wild type” P-53.  Therefore, in recent years there has been considerable research on how to get the P53 going again in those cancers.  This blog entry reviews that and other research relevant to P53 and where it appears to be heading as a promising new anti-cancer approach.

The introduction to a 2010 review article Targeting p53 for Novel Anticancer Therapy sets the stage.  “Carcinogenesis is a multistage process, involving oncogene activation and tumor suppressor gene inactivation as well as complex interactions between tumor and host tissues, leading ultimately to an aggressive metastatic phenotype. Among many genetic lesions, mutational inactivation of p53 tumor suppressor, the “guardian of the genome,” is the most frequent event found in 50% of human cancers. p53 plays a critical role in tumor suppression mainly by inducing growth arrest, apoptosis, and senescence, as well as by blocking angiogenesis. In addition, p53 generally confers the cancer cell sensitivity to chemoradiation. Thus, p53 becomes the most appealing target for mechanism-driven anticancer drug discovery. This review will focus on the approaches currently undertaken to target p53 and its regulators with an overall goal either to activate p53 in cancer cells for killing or to inactivate p53 temporarily in normal cells for chemoradiation protection.”

The amazing P53 and cell metabolism

P53 plays other roles besides regulating cell cycle arrest and apoptosis in the presence of strong stress.  The 2009 publication Homeostatic functions of the p53 tumor suppressor: regulation of energy metabolism and antioxidant defense describes an additional role. “The p53 tumor suppressor plays pivotal role in the organism by supervising strict compliance of individual cells to needs of the whole organisms. It has been widely accepted that p53 acts in response to stresses and abnormalities in cell physiology by mobilizing the repair processes or by removing the diseased cells through initiating the cell death programs. Recent studies, however, indicate that even under normal physiological conditions certain activities of p53 participate in homeostatic regulation of metabolic processes and that these activities are important for prevention of cancer. These novel functions of p53 help to align metabolic processes with the proliferation and energy status, to maintain optimal mode of glucose metabolism and to boost the energy efficient mitochondrial respiration in response to ATP deficiency. Additional activities of p53 in non-stressed cells tune up the antioxidant defense mechanisms reducing the probability of mutations caused by DNA oxidation under conditions of daily stresses. The deficiency in the p53-mediated regulation of glycolysis and mitochondrial respiration greatly accounts for the deficient respiration of the predominance of aerobic glycolysis in cancer cells (the Warburg effect), while the deficiency in the p53-modulated antioxidant defense mechanisms contributes to mutagenesis and additionally boosts the carcinogenesis process.”  The suggestion is therefore that maintaining strong P53 activity is an important aspect of maintaining health. 

The role of P53 in cell respiration was described in the 2006 publication p53 aerobics: the major tumor suppressor fuels your workout.  “In addition to its role as the central regulator of the cellular stress response, p53 can regulate aerobic respiration via the novel transcriptional target SCO2, a critical regulator of the cytochrome c oxidase complex (Matoba et al., 2006). Loss of p53 results in decreased oxygen consumption and aerobic respiration and promotes a switch to glycolysis, thereby reducing endurance during physical exercise.” 

 The glycolysis provides an ideal environment for carcinogenesis.  As stated in the 2006 paper p53 regulates mitochondrial respiration, “The energy that sustains cancer cells is derived preferentially from glycolysis. This metabolic change, the Warburg effect, was one of the first alterations in cancer cells recognized as conferring a survival advantage. Here, we show that p53, one of the most frequently mutated genes in cancers, modulates the balance between the utilization of respiratory and glycolytic pathways. We identify Synthesis of Cytochrome c Oxidase 2 (SCO2) as the downstream mediator of this effect in mice and human cancer cell lines.  SCO2 is critical for regulating the cytochrome c oxidase (COX) complex, the major site of oxygen utilization in the eukaryotic cell. Disruption of the SCO2 gene in human cancer cells with wild-type p53 recapitulated the metabolic switch toward glycolysis that is exhibited by p53-deficient cells. That SCO2 couples p53 to mitochondrial respiration provides a possible explanation for the Warburg effect and offers new clues as to how p53 might affect aging and metabolism.”

Recapitulating in simple terms, deficiency or mutation of P53 switches the respiratory environment in cells to glycolysis favoring cancer development.  This is in addition to inactivated or mutated P53 being unable to kill off cancer cells by apoptosis.  The research literature of cancer metabolism and its relationship to mitochondrial signaling is very rich and interesting and I was tempted to cite more publications in that area.  However, I choose to focus on P53 here.

Mutations of P53 in cancers

The 2007 paper Restoration of wild-type p53 function in human tumors: strategies for efficient cancer therapy points out “The p53 tumor suppressor gene is mutated in around 50% of all human tumors. Most mutations inactivate p53’s specific DNA binding, resulting in failure to activate transcription of p53 target genes. As a consequence, mutant p53 is unable to trigger a p53-dependent biological response, that is cell cycle arrest and apoptosis. Many tumors express high levels of nonfunctional mutant p53. Several strategies for restoration of wild-type p53 function in tumors have been designed. Wild-type p53 reconstitution by adenovirus-mediated gene transfer has shown antitumor efficacy in clinical trials. Screening of chemical libraries has allowed identification of small molecules that reactivate mutant p53 and trigger mutant p53-dependent apoptosis. These novel strategies raise hopes for more efficient cancer therapy.”  As will be explained, not only is there the issue of mutant P53 in some cancers, but there is also an issue of wild-type (normal) P53 in other cancers being inactivated by the cancer.

MDM2 and MDMX

Two key proteins are known to play roles in both normal and cancer P53 homeostasis MDM2 and MDMX.  Regulation of these proteins may offer an important cancer therapy approach, not only in cells with mutated P53 but also in cancer cells with wild-type P53.  The 2010 review paper The regulation of MDM2 by multisite phosphorylation–opportunities for molecular-based intervention to target tumours? explains: “The p53 tumour suppressor is a tightly controlled transcription factor that coordinates a broad programme of gene expression in response to various cellular stresses leading to the outcomes of growth arrest, senescence, or apoptosis. MDM2 is an E3 ubiquitin ligase that plays a key role in maintaining p53 at critical physiological levels by targeting it for proteasome-mediated degradation. Expression of the MDM2 gene is p53-dependent and thus p53 and MDM2 operate within a negative feedback loop in which p53 controls the levels of its own regulator. Induction and activation of p53 involves mainly the uncoupling of p53 from its negative regulators, principally MDM2 and MDMX, an MDM2-related and -interacting protein that inhibits p53 transactivation function. MDM2 is tightly regulated through various mechanisms including gene expression, protein turnover (mediated by auto-ubiquitylation), protein-protein interaction with key regulators, and post-translational modification, mainly, but not exclusively, by multisite phosphorylation.–. This analysis also provides an opportunity to consider the signalling pathways regulating MDM2 as potential targets for non-genotoxic therapies aimed at restoring p53 function in tumour cells.”

Many cancers have in the course of evolution developed a strategy for inactivating P53 using MDM2.  Reactivating MDM2 has therefore been considered as an anti-cancer strategy.  The 2008 publication Reactivation of p53 by a specific MDM2 antagonist (MI-43) leads to p21-mediated cell cycle arrest and selective cell death in colon cancer states “MDM2 oncoprotein binds directly to the p53 tumor suppressor and inhibits its function in cancers retaining wild-type p53. Blocking this interaction using small molecules is a promising approach to reactivate p53 function and is being pursued as a new anticancer strategy.– This study suggests that p53 activation by a potent and specific spiro-oxindole MDM2 antagonist may represent a promising therapeutic strategy for the treatment of colon cancer and should be further evaluated in vivo and in the clinic.”

A somewhat broader view of the same situation is offered in the previously-mentioned 2007 paper Restoration of wild-type p53 function in human cancer: relevance for tumor therapy.  “BACKGROUND: In the majority of human cancers, the tumor suppressor activity of p53 is impaired because of mutational events or interactions with other proteins (i.e., MDM2). The loss of p53 function is responsible for increased aggressiveness of cancers, while tumor chemoresistance and radioresistance are dependent upon the expression of mutant p53 proteins. METHODS: Review of the literature indicates that p53 acts primarily as a transcription factor whose function is subject to a complex and diverse array of covalent post-translational modifications that markedly influence the expression of p53 target genes responsible for cellular responses such as growth arrest, senescence, or apoptosis. The ability of p53 to induce apoptosis in cancer cells is believed essential for cancer therapy. RESULTS: Numerous data indicate that p53 dependent apoptosis is a relevant factor in determining the efficacy of anticancer treatments. Thus, the development of new strategies for restoration of p53 function in human tumors is considered an important issue. Two main approaches for restoration of p53 function have been pursued that impact anticancer treatments: (a) de novo expression of wild-type p53 (wt-p53) through gene therapy and (b) identification of small molecules reactivating wt-p53 function. CONCLUSIONS: The extensive body of knowledge acquired has identified manipulations of p53 signaling as a relevant issue for successful therapies. In this context, the recognition of p53 status in cancer cells is significant and would help considerably in the selection of an appropriate therapeutic approach. p53 manipulations for cancer therapy have revealed the need for specificity of p53 activation and ability to spare body tissues. Furthermore, the promising results obtained by using molecules competent to reactivate wt-p53 functions in cancer cells provide the basis for the design of new molecules with lower side effects and higher anti-tumor efficiency. The reexpression and reactivation of p53 protein in human cancer cells would increase tumor susceptibility to radiation or chemotherapy enhancing the efficacy of standard therapeutic protocols.”

Numerous other publications have been concerned with reactivation of the P53 pathway in cancers including the 2005 publication Nongenotoxic activation of the p53 pathway as a therapeutic strategy for multiple myeloma.  “Mutation of p53 is a rare event in multiple myeloma, but it is unknown if p53 signaling is functional in myeloma cells, and if targeted nongenotoxic activation of the p53 pathway is sufficient to kill tumor cells. Here, we demonstrate that treatment of primary tumor samples with a small-molecule inhibitor of the p53-murine double minute 2 (MDM2) interaction increases the level of p53 and induces p53 targets and apoptotic cell death.”    

The 2010 publication Controlling the Mdm2-Mdmx-p53 Circuit offers a note of caution “Two human family members, Mdm2 and Mdmx, are primarily responsible for inactivating p53 transcription and targeting p53 protein for ubiquitin-mediated degradation. — In tumors that harbor wild-type p53, reactivation of p53 by modulating both Mdm2 and Mdmx signaling is well suited as a therapeutic strategy. However, the rationale for development of kinase inhibitors that target the Mdm2-Mdmx-p53 axis must be carefully considered since modulation of certain kinase signaling pathways has the potential to destabilize and inactivate p53.”  The interactions are quite complex.

Enter Nutlins 

There is great interest in a new class of MDM2 inhibitors called Nutlins.  “Nutlins are cis-imidazoline analogs which inhibit the interaction between MDM2 and p53, and were discovered by screening a chemical library by Vassiliev et al. Nutlin-1, Nutlin-2 and Nutlin-3 were all identified in the same screen,^[1] however Nutlin-3 is the compound most commonly used in anti-cancer studies.^[2]  Inhibiting the interaction between MDM2 and p53 stabilizes p53 and is thought to selectively kill cancer cells. These compounds are therefore thought to work best on tumors that contain normal or wild type p53(ref).”

The 2008 publication The MDM2 inhibitor Nutlins as an innovative therapeutic tool for the treatment of haematological malignancies tells the story. “At variance to solid tumors, which show percentage of p53 deletions and/or mutations close to 50%, more than 80% of haematological malignancies express wild-type p53 at diagnosis. Therefore, activation of the p53 pathway by antagonizing its negative regulator murine double minute 2 (MDM2) might offer a new therapeutic strategy for the great majority of haematological malignancies. Recently, potent and selective small-molecule MDM2 inhibitors, the Nutlins, have been identified. Studies with these compounds have strengthened the concept that selective, non-genotoxic p53 activation might represent an alternative to the current cytotoxic chemotherapy. Interestingly, Nutlins not only are able to induce apoptotic cell death when added to primary leukemic cell cultures, but also show a synergistic effect when used in combination with the chemotherapeutic drugs commonly used for the treatment of haematological malignancies. Of interest, Nutlins also display non-cell autonomous biological activities, such as inhibition of vascular endothelial growth factor, stromal derived factor-1/CXCL12 and osteprotegerin expression and/or release by primary fibroblasts and endothelial cells. Moreover, Nutlins have a direct anti-angiogenic and anti-osteoclastic activity. Thus, Nutlins might have therapeutic effects by two distinct mechanisms: a direct cytotoxic effect on leukemic cells and an indirect non-cell autonomous effect on tumor stromal and vascular cells, and this latter effect might be therapeutically relevant also for treatment of haematological malignancies carrying p53 mutations.”

A number of other 2010 papers are also concerned with the use of Nutlins as P-53 activating cancer therapies, including Nutlin-3 enhances tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis through up-regulation of death receptor 5 (DR5) in human sarcoma HOS cells and human colon cancer HCT116 cells and Pharmacological activation of the p53 pathway in haematological malignancies.  “p53 gene mutations are rarely detected at diagnosis in common haematological cancers such as multiple myeloma (MM), acute myeloid leukaemia (AML), chronic lymphocytic leukaemia (CLL) and Hodgkin’s disease (HD), although their prevalence may increase with progression to more aggressive or advanced stages. Therapeutic induction of p53 might therefore be particularly suitable for the treatment of haematological malignancies. Some of the anti-tumour activity of current chemotherapeutics has been derived from activation of p53. However, until recently it was unknown whether p53 signalling is functional in certain haematological cancers including MM and if p53 activity is sufficient to trigger an apoptotic response. With the recent discovery of nutlins, which represent the first highly selective small molecule inhibitors of the p53-MDM2 interaction, pharmacological tools are now available to induce p53 irrespective of upstream signalling defects, and to functionally analyse the downstream p53 pathway in primary leukaemia and lymphoma cells. Combination therapy is emerging as a key factor, and development of non-genotoxic combinations seems very promising for tackling the problems of toxicity and resistance. This review will highlight recent findings in the research into molecules capable of modulating p53 protein activities and mechanisms that activate the p53 pathway, restoring response to therapy in haematological malignancies.” 

Nutlins and Vitamin D. 

What about supplements in the anti-aging firewalls regimen and activation of P-53 and the other pro-apoptotic channels in cancers?  There is much to say about that subject and it has to be the focus of a separate blog entry.  However, I stumbled across one paper relevant to the present discussion 1,25-dihydroxyvitamin D3 enhances the apoptotic activity of MDM2 antagonist nutlin-3a in acute myeloid leukemia cells expressing wild-type p53.  in leukemia cells expressing wild-type P-53 “Combination of nutlin-3a with 1,25D accelerated programmed cell death, likely because of enhanced nutlin-induced upregulation of the proapoptotic PIG-6 protein and downregulation of antiapoptotic BCL-2, MDMX, human kinase suppressor of Ras 2, and phosphorylated extracellular signal-regulated kinase 2.” 

The scope of the relevant research literature is overwhelming.  A search in Pubmed on Nutlin produces 220 references!  What I have included here should be enough to convey the general picture, however.  A search in clinicaltrials.gov on “nutlin and cancer” failed to reveal any trials, suggesting that nutlin-based cancer therapies are not yet in the clinical trials phase.  I expect such clinical trials will be launched soon. 

The bottom line               

Turning on a strong P53 defense is emerging as an important anticancer strategy in the advanced research stage.  A central approach for cancers with wild-type P53 is to inhibit the P53-controlling proteins MDM2 and MDMX using a new class of substances called Nutlins.  This approach is not yet in clinical trials but probably soon will be.  A separate blog entry will deal with the anti-cancer capabilities of supplements in the anti-aging firewalls regimen.

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22. July 2010 by admin.

In the post Diabetes Part I: Biology and molecular dynamics of diabetes, I described a pathological biomolecular process through which diabetes arises from obesity or metabolic syndrome.  I also provided reference links to publications amplifying on the details of the process, including some 2010 findings. 

The context of the following discussion is that of the CDC and many other respectable organizations – Type 2 diabetes is preventable and controllable(ref).   

Control of diabetes via drugs is a mainline approach in our society.  Much speculation has appeared recently in the popular news regarding the safety of the diabetes drug Avandia (rosiglitazone) and whether the FDA will continue to allow it to stay on the market.  Avandia appears to significantly increase fluid retention and the probability of heart attacks and heart disease, but this week a panel of experts convened by the FDA voted to recommend keeping the drug on the market.  “Only 12 of the 33 members voted to withdraw Avandia, while an additional 10 voted to allow the drug to be prescribed only with severe limitations such as requiring physicians and patients to be educated about its risks. The panel, like the FDA itself, was largely divided over what to make of Avandia’s potential health risks(ref).”  The commercial stakes are enormous since the market for non-insulin oral diabetes drugs is estimated to be $8.4 billion dollars(ref). 

In the March 2010 blog post Recent diabetes-related clinical trials , I reviewed five recent clinical trials related to diabetes treatments, three that have failed and two that have succeeded.  I concluded by commenting on what I thought were some important underlying messages, including:

·        The clinical trial failures indicate how much we still are in an extremely expensive trial-and-error approach to treating diabetes, as I believe is the case for multiple other diseases. 

·        All the treatments that were the subjects of the trials related to management of diabetic conditions or cardiovascular risk factors.  Such management is extremely important but lifestyle and dietary factors can be equally or even more important in preventing onset of diabetes as well as its management.   

This last point is what this current blog entry is about.  While drugs may be important for control of diabetes for some patients, this blog post looks in a different direction – to lifestyle, dietary and food supplement interventions.  In this post, I will characterize how certain of the lifestyle, dietary habits and supplements in the anti-aging firewalls regimens work on a molecular level to disrupt the diabetes process.  These lifestyle and dietary factors are extremely relevant.

“A number of lifestyle factors are known to be important to the development of type 2 diabetes. In one study, those who had high levels of physical activity, a healthy diet, did not smoke, and consumed alcohol in moderation had an 82% lower rate of diabetes. When a normal weight was included the rate was 89% lower. In this study a healthy diet was defined as one high in fiber, with a high polyunsaturated to saturated fat ratio, and a lower mean glycemic index(ref).  Obesity has been found to contribute to approximately 55% type 2 diabetes(ref), and decreasing consumption of saturated fats and trans fatty acids while replacing them with unsaturated fats may decrease the risk(ref).  The increased rate of childhood obesity in between the 1960s and 2000s is believed to have led to the increase in type 2 diabetes in children and adolescents(ref).^[8]”  

The Role of Exercise

It has long been known that, just as a sedentary lifestyle is a risk factor for Type 2 diabetes (ref)(ref), so is physical activity and exercise an important preventative activity. Back in 2002 the US Department of Health and Human Services published a position document Physical Activity Fundamental To Preventing Disease and the message of that document still stands.  In that study, “vigorous physical activity is defined as exercise that made the respondent sweat and breathe hard for at least 20 minutes on 3 or more of the 7 days preceding the survey.”  

How exercise works is described in very simple terms in the American Diabetes Association’s web page The Science of Exercise - Is physical activity the best medicine?  “It’s free — Yes, it’s the crux of healthy living: exercise. And while just about everyone is better off working out regularly, exercise is, in some sense, the perfect drug for diabetes. Not only can it improve blood glucose control—which in itself reduces the risk of diabetes complications—but research suggests it may combat heart disease, weight gain, depression, and more. — Muscle contractions have a powerful effect on how the body processes glucose, the original biofuel. The muscles are the major consumer of glucose during exercise. It’s not surprising since they do most of the work. In each cell, muscles store dense packets of glucose, accounting for around 2,000 calories worth of energy throughout the body, according to Sheri Colberg-Ochs, PhD, a professor of exercise science at Old Dominion University in Norfolk, Va. “[This energy] just stays there unless you contract the muscle.” — During exercise, the muscles deplete their individual glucose reserves. To help restock their glucose supplies, the muscles change in two important ways: They become more sensitive to insulin—a hormone that escorts glucose from the bloodstream into body cells—and they also start to absorb glucose on their own, independently of insulin. — This second pathway created during exercise is a boon for anyone with type 2 diabetes, which is marked by insulin resistance. “When the body is at rest, it has one mechanism for getting glucose out of the bloodstream. That way is insulin,” says Colberg-Ochs. “What’s so good about exercise is that even if the muscles are insulin resistant at rest, that’s irrelevant with exercise.”  – Exercise’s effect on glucose use occurs not just in people with type 2 but in almost everyone, including those with type 1 and pre-diabetes. A large study found that, in people with pre-diabetes, lifestyle changes that included 150 minutes a week of moderate-intensity exercise reduced the risk of progression to full-blown type 2 diabetes by 58 percent.”

Over the years there have been many studies and publications relating exercise to the control of diabetes.  One of the latest is a July 2010 publication Is exercise a therapeutic tool for improvement of cardiovascular risk factors in adolescents with type 1 diabetes mellitus? A randomised controlled trial. “RESULTS: Exercise improved glycemic control by reducing HbA1c values in exercise groups (P=0.03, P=0.01 respectively) and no change in those who were not physically active (P=0.2). Higher levels of HbA1c were associated with higher levels of cholesterol, LDL-c, and triglycerides (P = 0.000 each). In both groups B and C , frequent exercise improved dyslipidemia and reduced insulin requirements significantly (P=0.00 both), as well as a reduction in BMI (P=0.05,P=0.00 respectively) and waist circumference(P=0.02, P=0.00 respectively). The frequency of hypoglycemic attacks were not statistically different between the control group and both intervention groups (4.7 +/- 3.56 and 4.82+/-4.23 ,P= 0.888 respectively ). Reduction of blood pressure was statistically insignificant apart from the diastolic blood presure in group C (P=0.04). CONCLUSION: Exercise is an indispensable component in the medical treatment of patients with T1DM as it improves glycemic control and decreases cardiovascular risk factors among them.”This theme of the importance of exercise is based on solid science as well as population studies and is reiterated in most serious articles on diabetes aimed at consumers and patients.  “Physical activity is a key component of lifestyle change. In addition to helping a patient lose weight, exercise leads to a reduction in body fat, blood pressure and insulin resistance. Researchers report a one percent decrease in hemoglobin A1c levels (a marker of long-term glucose control) is associated with a 15 to 20 percent reduction in risk for cardiovascular complications and a 37 percent reduction in microvascular complications (like eye, kidney and nerve disease)(ref).”

Exercise!  Personally, I strive for 45 minutes of exercise a day which could consist of mowing the lawn, brisk walking, swimming, treadmilling, yardwork or swimming.

Diet – foods to avoid

A number of publications stress the negative role in diabetes of consumption of saturated fats and trans fats.  The 2003 publication Quality of dietary fatty acids, insulin sensitivity and type 2 diabetes reported “Epidemiological evidence and intervention studies clearly indicate that the quality of dietary fat influences insulin sensitivity in humans, in particular, saturated fat worsens it, while monounsaturated and omega-6 polyunsaturated fats improve it. Long chain omega-3 fatty acids do not seem to have any effect on insulin sensitivity, at least in humans. Moreover, there is also good epidemiological evidence that the quality of dietary fat may influence the risk of type 2 diabetes, again with saturated fat increasing and unsaturated fat decreasing this risk. No intervention study is available at the moment on this specific point, even if in the Finnish Diabetes Prevention Study the incidence of type 2 diabetes was reduced by a multifactorial intervention, which also included a reduction of saturated fat intake.”The evidence for this viewpoint continued to accumulate and the 2009 review publication Dietary fats and prevention of type 2 diabetes reported “Although type 2 diabetes is determined primarily by lifestyle and genes, dietary composition may affect both its development and complications. Dietary fat is of particular interest because fatty acids influence glucose metabolism by altering cell membrane function, enzyme activity, insulin signaling, and gene expression. This paper focuses on the prevention of type 2 diabetes and summarizes the epidemiologic literature on associations between types of dietary fat and diabetes risk. It also summarizes controlled feeding studies on the effects of dietary fats on metabolic mediators, such as insulin resistance. Taken together, the evidence suggests that replacing saturated fats and trans fatty acids with unsaturated (polyunsaturated and/or monounsaturated) fats has beneficial effects on insulin sensitivity and is likely to reduce risk of type 2 diabetes. Among polyunsaturated fats, linoleic acid from the n-6 series improves insulin sensitivity. On the other hand, long-chain n-3 fatty acids do not appear to improve insulin sensitivity or glucose metabolism. In dietary practice, foods rich in vegetable oils, including non-hydrogenated margarines, nuts, and seeds, should replace foods rich in saturated fats from meats and fat-rich dairy products. Consumption of partially hydrogenated fats should be minimized.”

A finer-tuning of this viewpoint can be found in the 2010 publication Session 4: CVD, diabetes and cancer: Diet, insulin resistance and diabetes: the right (pro)portions  “Excess energy intake and positive energy balance are associated with the development of obesity and insulin resistance, which is a key feature underlying the pathophysiology of type 2 diabetes. It is possible that dietary macronutrient intake may also be important, in particular increased levels of sugar and fat. High-fat energy-dense diets contribute to energy excess and obesity. Fat type is also a factor, with evidence suggesting that saturated fat intake is linked to insulin resistance. However, controversy exists about the role of carbohydrate in the development of diabetes. Epidemiological studies suggest that the risk of diabetes is unrelated to the total amount of carbohydrate, but that fibre intake and glycaemic load are important. Common dietary advice for the prevention of diabetes often advocates complex carbohydrates and restriction of simple carbohydrates; however, sugars may not be the main contributor to glycaemic load. Evidence continues to emerge in relation to the influence of dietary sugars intake on insulin resistance. In broader dietary terms fruit and vegetable intake may influence insulin resistance, possibly related to increased intake of fibre and micronutrients or displacement of other food types. There is also considerable debate about the most effective diet and appropriate macronutrient composition to facilitate weight loss. Recent evidence suggests comparable effects of diets with varying macronutrient profiles on weight loss, which is predominantly related to energy restriction. However, based on the results of diabetes prevention trials focusing on lifestyle measures, evidence favours low-fat diets as the preferred approach for weight loss and diabetes prevention.”

Avoid saturated fats and trans-fats!

Foods with positive qualities with respect to diabetes

A number of foods with strong phytochemical  content can counter the underlying processes of diabetes, a key message of the 2010 review paper Functional food targeting the regulation of obesity-induced inflammatory responses and pathologies.  I can only discuss a few representative foods here as examples.   

Blueberries

The blog entry Back to blueberries points out the role of pterostilbene, a key phytochemical in blueberries, in controlling tissue glycation and associated inflammation in diabetes.  Pterostilbene is a stilbenoid chemically related to resveratrol.  It is  a powerful anti-inflammatory, responsible for some of the effects of blueberries in controlling a range of inflammatory disease conditions. 

One of the theories of aging is Tissue Glycation, a process deeply implicated in diabetes.  Tissue glycation involves cross linking of tissue proteins with sugars resulting in the formation of Advanced Glycation Endproducts (AGEs).  The result of AGEs can be self-propagating systemic or “silent” tissue inflammation. AGEs are recognized by cell RAGE receptors which result in the production of cytokine chemicals that can induce unwanted and potentially deadly inflammation in blood vessels, nerve, liver and other tissues. Atherosclerosis can be a consequence. AGEs are responsible for much bodily mischief related to aging leading to deterioration of function and structure of organs. They play important roles in diabetes, atherosclerosis, vascular disease, kidney failure, and neuropathy including Alzheimer’s disease. The presence of AGEs also appears to negatively impact on immune system functioning.  Diabetes in particular appears to have its roots due both to inflammation and to glycation.  People with high blood sugar levels, diabetics and pre-diabetes are particularly susceptible to glycation. 

I will quote only two of the publications relating blueberries to diabetes.  The 2009 publication states Antiobesity and antidiabetic effects of biotransformed blueberry juice in KKAy mice reports “Biotransformation of blueberry juice by the Serratia vaccinii bacterium gave rise to adenosine monophosphate-activated protein kinase (AMPK) phosphorylation and glucose uptake in muscle cells and adipocytes, but inhibited adipogenesis. This study investigated the antiobesity and antidiabetic potential of biotransformed blueberry juice (BJ) in KKA^y mice, rodent model of leptin resistance. — Incorporating BJ in drinking water protected young KKA^y mice from hyperphagia and significantly reduced their weight gain. Moreover, BJ protected young KKA^y mice against the development of glucose intolerance and diabetes mellitus. Chronic BJ administration in obese and diabetic KKA^y mice reduced food intake and body weight. This effect could not fully explain the associated antidiabetic effect because BJ-treated mice still showed lower blood glucose level when compared with pair-fed controls. The adipokines pathway also seems to be involved because BJ significantly increased adiponectin levels in obese mice.  – Conclusions: This study shows that BJ decreases hyperglycemia in diabetic mice, at least in part by reversing adiponectin levels. BJ also protects young pre-diabetic mice from developing obesity and diabetes. Thus, BJ may represent a novel complementary therapy and a source of novel therapeutic agents against diabetes mellitus.” 

Another relevant  publication is Dietary blueberry attenuates whole-body insulin resistance in high fat-fed mice by reducing adipocyte death and its inflammatory sequelae. “These results suggest that cytoprotective and antiinflammatory actions of dietary BB can provide metabolic benefits to combat obesity-associated pathology.”   

Eat blueberries! 

Other colored berries 

There are other papers describing anti-diabetic effects of blueberries and other colored berries such as Whole berries versus berry anthocyanins: interactions with dietary fat levels in the C57BL/6J mouse model of obesity and Inhibition of cancer cell proliferation and suppression of TNF-induced activation of NFkappaB by edible berry juice.

Eat strawberries, raspberries and other colored berries!  

Avocados

The blog entry Calorie restriction mimetics – focus on avocado extract points to a sugar in avocados, mannoheptulose, that is highly relevant for the control of diabetes.  “Mannoheptulose is a hexokinase inhibitor. It is a heptose, a monosaccharide with seven carbon atoms. By blocking the enzyme hexokinase, it prevents glucose phosphorylation. As a result less dextrose units are broken down into smaller molecules in an organism. It is found as D-mannoheptulose in avocado(ref).^[1] ” In simple terms, it works to block the metabolism if glucose. “When fed to mice in fairly concentrated doses (roughly 300 milligrams per kilogram of an animal’s body weight), it improved insulin sensitivity and the clearance of glucose from the blood. Meaning it helped overcome diabetes-like impairments to blood-sugar control. MH supplementation also improved the ability of insulin, a hormone, to get cells throughout the body to do its bidding (and that’s a good thing).  MH revved up the burning of fats in muscle(ref).”

Eat avocados!

Tomatoes

The 2008 paper Inhibitory effect of naringenin chalcone on inflammatory changes in the interaction between adipocytes and macrophages has some very interesting things to say related to the diabetic process as described in the Diabetes Part 1 blog entry.  For one thing, Naringenin Chalcone is not a Sicilian mobster; it is a phytochemical in tomatos.  “Obese adipose tissue is characterized by an enhanced infiltration of macrophages. It is considered that the paracrine loop involving monocyte chemoattractant protein (MCP)-1 and tumor necrosis factor (TNF)-alpha between adipocytes and macrophages establishes a vicious cycle that augments the inflammatory changes and insulin resistance in obese adipose tissue. Polyphenols, which are widely distributed in fruit and vegetables, can act as antioxidants and some of them are also reported to have anti-inflammatory properties. Tomato is one of the most popular and extensively consumed vegetable crops worldwide, which also contains many flavonoids, mainly naringenin chalcone. We investigated the effect of flavonoids, including naringenin chalcone, on the production of proinflammatory mediators in lipopolysaccharide (LPS)-stimulated macrophages and in the interaction between adipocytes and macrophages. Naringenin chalcone inhibited the production of TNF-alpha, MCP-1, and nitric oxide (NO) by LPS-stimulated RAW 264 macrophages in a dose-dependent manner. Coculture of 3T3-L1 adipocytes and RAW 264 macrophages markedly enhanced the production of TNF-alpha, MCP-1, and NO compared with the control cultures; however, treatment with naringenin chalcone dose-dependently inhibited the production of these proinflammatory mediators. These results indicate that naringenin chalcone exhibits anti-inflammatory properties by inhibiting the production of proinflammatory cytokines in the interaction between adipocytes and macrophages. Naringenin chalcone may be useful for ameliorating the inflammatory changes in obese adipose tissue.”  Of course tomatoes also contain lycopene and other healthful ingredients.

Eat tomatoes!

Citrus fruits

The 2008 paper Auraptene, a citrus fruit compound, regulates gene expression as a PPARalpha agonist in HepG2 hepatocytes indicates “Citrus fruit compounds have various activities that improve pathological conditions in many tissues. In this study, we examined the effect of auraptene contained mainly in the peel of citrus on peroxisome proliferator-activated receptor-alpha (PPARalpha) activation. — These results indicate that auraptene acts as a PPARalpha agonist in hepatocytes and that auraptene may improve lipid abnormality through PPARalpha activation in the liver.”  The point is reinforced in the 2007 paper Citrus auraptene acts as an agonist for PPARs and enhances adiponectin production and MCP-1 reduction in 3T3-L1 adipocytes. 

In other words, that strong pungent stuff in lemon and orange peels could be a good diabetes-fighter. Eat them!

Herbs and spices

Capsaicin

For those of you who are hot pepper freaks and a bit overweight or concerned about diabetes, there is good news going back to the 1986 publication Capsaicin-induced beta-adrenergic action on energy metabolism in rats: influence of capsaicin on oxygen consumption, the respiratory quotient, and substrate utilization.  The 2003 publication Capsaicin exhibits anti-inflammatory property by inhibiting IkB-a degradation in LPS-stimulated peritoneal macrophages casts light on how capsaicin works to control inflammation leading to diabetes.  And so does the 2007 publication Capsaicin, a spicy component of hot peppers, modulates adipokine gene expression and protein release from obese-mouse adipose tissues and isolated adipocytes, and suppresses the inflammatory responses of adipose tissue macrophages.   “Capsaicin inhibited the expressions of IL-6 and MCP-1 mRNAs and protein release from the adipose tissues and adipocytes of obese mice, whereas it enhanced the expression of the adiponectin gene and protein. The action of capsaicin is associated with NF-kappaB inactivation and/or PPARgamma activation. Moreover, capsaicin suppressed not only macrophage migration induced by the adipose tissue-conditioned medium, but also macrophage activation to release proinflammatory mediators.”  These are exactly the actions needed to impede or stop the diabetic process described in the previous Diabetes Part 1 blog entry.

The 2009 publication The acute effects of a lunch containing capsaicin on energy and substrate utilisation, hormones, and satiety reports “An acute lunch containing capsaicin had no effect on satiety, EE, and PYY, but increased GLP-1 and tended to decrease ghrelin.”    That is, the lunch decreased the hunger protein ghrelin and hunger signaling. 

Eat hot red peppers and use hot red pepper sauce!

Spices, tea and caffeine

The 2006 publication Metabolic effects of spices, teas, and caffeine reports “Consumption of spiced foods or herbal drinks leads to greater thermogenesis and in some cases to greater satiety. In this regard, capsaicin, black pepper, ginger, mixed spices, green tea, black tea and caffeine are relevant examples. These functional ingredients have the potential to produce significant effects on metabolic targets such as satiety, thermogenesis, and fat oxidation. A significant clinical outcome sometimes may appear straightforwardly but also depends too strongly on full compliance of subjects. Nevertheless, thermogenic ingredients may be considered as functional agents that could help in preventing a positive energy balance and obesity.” 

Eat spicy foods and generously use spices!  See the blog posts Spices of life and Rosmarinic acid.

Herbal medicines

The 2002 publication Dual action of isoprenols from herbal medicines on both PPARgamma and PPARalpha in 3T3-L1 adipocytes and HepG2 hepatocytes reports “Several herbal medicines improve hyperlipidemia, diabetes and cardiovascular diseases. — In this study, we found that several isoprenols, common components of herbal plants, activate human peroxisome proliferator-activated receptors (PPARs) as determined using the novel GAL4 ligand-binding domain chimera assay system with coactivator coexpression. Farnesol and geranylgeraniol that are typical isoprenols in herbs and fruits activated not only PPARgamma but also PPARalpha as determined using the chimera assay system. These compounds also activated full-length human PPARgamma and PPARalpha in CV1 cells. Moreover, these isoprenols upregulated the expression of some lipid metabolic target genes of PPARgamma and PPARalpha in 3T3-L1 adipocytes and HepG2 hepatocytes, respectively. These results suggest that herbal medicines containing isoprenols with dual action on both PPARgamma and PPARalpha can be of interest for the amelioration of lipid metabolic disorders associated with diabetes.” “Farnesol is present in many essential oils such as citronella, neroli, cyclamen, lemon grass, tuberose, rose, musk, balsam and tolu(ref).”  Geranylgeraniol is present in Pterodon pubescens Benth seeds which “are commercially available in the Brazilian medicinal plant street market. The crude alcoholic extracts of this plant are used in folk medicine as anti-inflammatory, analgesic, and anti-rheumatic preparations(ref).”

Except for readers who may be deeply into herbal medicine or who visit Brazil frequently, I suggest trying other practical substances like blueberries and tomatoes.

Pungent spices

The 2007 paper Active spice-derived components can inhibit inflammatory responses of adipose tissue in obesity by suppressing inflammatory actions of macrophages and release of monocyte chemoattractant protein-1 from adipocytes relates to both spices consumed with foods and spices taken that can be taken as supplements like curcumin and ginger. “Macrophage activation was estimated by measuring tumor necrosis factor-alpha (TNF-alpha), nitric oxide, and monocyte chemoattractant protein-1 (MCP-1) concentrations. The active spice-derived components markedly suppressed the migration of macrophages induced by the mesenteric adipose tissue-conditioned medium in a dose-dependent manner. Among the active spice-derived components studied, allyl isothiocyanate, zingerone, and curcumin significantly inhibited the cellular production of proinflammatory mediators such as TNF-alpha and nitric oxide, and significantly inhibited the release of MCP-1 from 3T3-L1 adipocytes. Our findings suggest that the spice-derived components can suppress obesity-induced inflammatory responses by suppressing adipose tissue macrophage accumulation or activation and inhibiting MCP-1 release from adipocytes. These spice-derived components may have a potential to improve chronic inflammatory conditions in obesity.”  Allyl isothiocyanate “is responsible for the pungent taste of mustard, horseradish, and wasabi(ref).” Zingerone gives the zing to ginger.

Eat ginger, mustard and horseradish if you can take it!

Cinnamon

The 2010 publication Antidiabetic effects of cinnamon oil in diabetic KK-A(y) mice reports on studying the hypoglycemic effect of cinnamon oil (CO) in a type 2 diabetic animal model.  “CO was administrated at doses of 25, 50 and 100mg/kg for 35days. It was found that fasting blood glucose concentration was significantly decreased (P<0.05) with the 100mg/kg group (P<0.01) the most efficient compared with the diabetic control group. In addition, there was significant decrease in plasma C-peptide, serum triglyceride, total cholesterol and blood urea nitrogen levels while serum high density lipoprotein (HDL)-cholesterol levels were significantly increased after 35days. Meanwhile, glucose tolerance was improved, and the immunoreactive of pancreatic islets beta-cells was promoted. These results suggest that CO had a regulative role in blood glucose level and lipids, and improved the function of pancreatic islets. Cinnamon oil may be useful in the treatment of type 2 diabetes mellitus.”  There is much current interest in use of cinnamon for treating diabetes. Other relevant 2010 and publications are

·        Cinnamon extract regulates glucose transporter and insulin-signaling gene expression in mouse adipocytes,

·        Cinnamon: Potential Role in the Prevention of Insulin Resistance, Metabolic Syndrome, and Type 2 Diabetes,

·        Cinnamon as a supplemental treatment for impaired glucose tolerance and type 2 diabetes.

Eat cinnamon and drink cinnamon tea!

Foods containing luteolin

Luteolin is another food substance that works against diabetes.  “Luteolin is a flavonoid; more specifically, it is one of the more common flavones.^[1] — Luteolin is most often found in leaves, but it is also seen in celery, thyme, dandelion, rinds, barks, clover blossom and ragweed pollen.^[1] It has also been isolated from Salvia tomentosa.^[3] Dietary sources include celery, green pepper, thyme, perilla, chamomile tea, carrots, olive oil, peppermint, rosemary and oregano(ref).^[4][5]  the 2009 paper Luteolin, a food-derived flavonoid, suppresses adipocyte-dependent activation of macrophages by inhibiting JNK activation reports “The findings indicate that luteolin can inhibit the interaction between adipocytes and macrophages to suppress the production of inflammatory mediators, suggesting that luteolin is a valuable food-derived compound for the treatment of metabolic syndrome.”

Eat celery, green pepper, thyme, perilla, carrots, olive oil, peppermint, rosemary and oregano and drink chamomile tea!

Green tea

The 2007 paper Obesity and thermogenesis related to the consumption of caffeine, ephedrine, capsaicin, and green tea and the 2010 oublication Green tea catechins, caffeine and body-weight regulation convey more or less the same bottom-line message.  “Positive effects on body-weight management have been shown using green tea mixtures. Green tea, by containing both tea catechins and caffeine, may act through inhibition of catechol O-methyl-transferase, and inhibition of phosphodiesterase. Here the mechanisms may also operate synergistically. A green tea-caffeine mixture improves weight maintenance, through thermogenesis, fat oxidation, and sparing fat free mass. The sympathetic nervous system is involved in the regulation of lipolysis, and the sympathetic innervation of white adipose tissue may play an important role in the regulation of total body fat in general. Taken together, these functional ingredients have the potential to produce significant effects on metabolic targets such as thermogenesis, and fat oxidation.” 

Drink green tea and/or take green tea capsules!

Dietary supplements

I have written before how many of the supplements in the combined anti-aging firewalls supplement regimen target inflammation and perhaps enhance longevity by inhibiting the expression of the cell transcription factor NF-kappaB.  In fact, 39 substances in the firewalls regimen do this.  Since inflammation and the expression of NF-kappaB play such key roles in the onset and maintenance of Type 2 diabetes, it should be no surprise that many of those same 39 substances are effective at controlling diabetes.  This blog entry is already getting very long, so I will limit the discussion to a few key examples: fish oils, curcumin, resveratrol, ginger, and pine bark extract.

Fish oils, DHA and EPA

The 2007 publication Prevention of high-fat diet-induced adipose tissue remodeling in obese diabetic mice by n-3 polyunsaturated fatty acids is one of a number of animal research studies examining the mechanism of how poly unsaturated fatty acids (PUFAs) combat diabetic effects.  “OBJECTIVE: Obesity is associated with reduced insulin sensitivity and extensive reorganization of adipose tissue. As polyunsaturated fatty acids (PUFA) appear to inhibit diabetes development, we investigated PUFA effects on markers of matrix remodeling in white adipose tissue. METHODS AND PROCEDURE: Male obese diabetic (db/db) mice were treated with either a low-fat standard diet (LF), or high-fat diets rich in saturated and monounsaturated fatty acids — RESULTS: HF/S treatment increased adipose tissue expression of a number of genes involved in matrix degradation including matrix metalloproteinase (MMP)-12, -14 and cathepsin K, L and S compared with LF. MMP-12 gene was expressed in macrophages and adipocytes, and MMP-12 protein colocalized with both cell types. In addition, mean adipocyte area increased by 1.6-fold in HF/S-treated mice. Genes essential for collagen production, such as procollagen I, III, VI, tenascin C and biglycan were upregulated in HF/S-treated animals as well. N-3 PUFA supplementation resulted in enrichment of these fatty acids in adipose tissue. Moreover, n-3 PUFA inhibited the HF/S-induced upregulation of genes involved in matrix degradation and production I restored mean adipocyte area and prevented MMP-12 expression in macrophages and adipocytes. CONCLUSION: N-3 PUFA prevent high-fat diet-induced matrix remodeling and adipocyte enlargement in adipose tissue of obese diabetic mice. Such changes could contribute to diabetes prevention by n-3 PUFA in obese patients.”

Another relevant publications is the 2006 paper Adipose tissue inflammation induced by high-fat diet in obese diabetic mice is prevented by n-3 polyunsaturated fatty acids.”   “n-3 PUFA prevent adipose tissue inflammation induced by high-fat diet in obese diabetic mice, thereby dissecting obesity from adipose tissue inflammation. These data suggest that beneficial effects of n-3 PUFA on diabetes development could be mediated by their effect on adipose tissue inflammation.”

Other relevant publications include the 2009 paper Cellular and molecular effects of n-3 polyunsaturated fatty acids on adipose tissue biology and metabolism, and the 2009 publication  n-3 PUFA: bioavailability and modulation of adipose tissue function “In rodents n-3 LC PUFA prevent the development of obesity and impaired glucose tolerance. The effects of n-3 LC PUFA are mediated transcriptionally by AMP-activated protein kinase and by other mechanisms. n-3 LC PUFA activate a metabolic switch toward lipid catabolism and suppression of lipogenesis, i.e. in the liver, adipose tissue and small intestine. This metabolic switch improves dyslipidaemia and reduces ectopic deposition of lipids, resulting in improved insulin signalling. Despite a relatively low accumulation of n-3 LC PUFA in adipose tissue lipids, adipose tissue is specifically linked to the beneficial effects of n-3 LC PUFA, as indicated by (1) the prevention of adipose tissue hyperplasia and hypertrophy, (2) the induction of mitochondrial biogenesis in adipocytes, (3) the induction of adiponectin and (4) the amelioration of adipose tissue inflammation by n-3 LC PUFA.”

Curcumin

It suffices for me to quote from only one of the latest publications relating curcumin to diabetes, the 2010 e-publication Targeting Inflammation-Induced Obesity and Metabolic Diseases by Curcumin and Other Nutraceuticals. “Several spices have been shown to exhibit activity against obesity through antioxidant and anti-inflammatory mechanisms. Among them, curcumin, a yellow pigment derived from the spice turmeric (an essential component of curry powder), has been investigated most extensively as a treatment for obesity and obesity-related metabolic diseases. Curcumin directly interacts with adipocytes, pancreatic cells, hepatic stellate cells, macrophages, and muscle cells. There, it suppresses the proinflammatory transcription factor nuclear factor-kappa B, signal transducer and activators of transcription-3, and Wnt/beta-catenin, and it activates peroxisome proliferator-activated receptor-gamma and Nrf2 cell-signaling pathways, thus leading to the downregulation of adipokines, including tumor necrosis factor, interleukin-6, resistin, leptin, and monocyte chemotactic protein-1, and the upregulation of adiponectin and other gene products. These curcumin-induced alterations reverse insulin resistance, hyperglycemia, hyperlipidemia, and other symptoms linked to obesity. Other structurally homologous nutraceuticals, derived from red chili, cinnamon, cloves, black pepper, and ginger, also exhibit effects against obesity and insulin resistance.”

Resveratrol

The 2010 publication Resveratrol attenuates hyperglycemia-mediated oxidative stress, proinflammatory cytokines and protects hepatocytes ultrastructure in streptozotocin-nicotinamide-induced experimental diabetic rats reports “The diminished activities of hepatic enzymic antioxidants as well as the decreased levels of hepatic non-enzymic antioxidants of diabetic rats were reverted to near normalcy by resveratrol administration. Moreover, the histological and ultrastructural observations evidenced that resveratrol effectively rescues the hepatocytes from hyperglycemia-mediated oxidative damage without affecting its cellular function and structural integrity. The findings of the present investigation demonstrated the hepatocyte protective nature of resveratrol by attenuating markers of hyperglycemia-mediated oxidative stress and antioxidant competence in hepatic tissues of diabetic rats.”  Other publications carry a similar message including the 2010 publication Ameliorative potential of resveratrol on proinflammatory cytokines, hyperglycemia mediated oxidative stress, and pancreatic beta-cell dysfunction in streptozotocin-nicotinamide-induced diabetic rats. “The results of the present investigation demonstrated that resveratrol exhibits significant antidiabetic potential by attenuating hyperglycemia, enhancing insulin secretion and antioxidant competence in pancreatic beta-cells of diabetic rats.” 

Ginger

The 2008 publication 6-Shogaol and 6-gingerol, the pungent of ginger, inhibit TNF-alpha mediated downregulation of adiponectin expression via different mechanisms in 3T3-L1 adipocytes.  “In this study, we demonstrated that the two ginger-derived components have a potent and unique pharmacological function in 3T3-L1 adipocytes via different mechanisms. Both pretreatment of 6-shogaol (6S) and 6-gingerol (6G) significantly inhibited the tumor necrosis factor-alpha (TNF-alpha) mediated downregulation of the adiponectin expression in 3T3-L1 adipocytes.” 

The 2006 publication Analgesic, antiinflammatory and hypoglycaemic effects of ethanol extract of Zingiber officinale (Roscoe) rhizomes (Zingiberaceae) in mice and rats reports “The findings of this experimental animal study indicate that Zingiber officinale rhizomes ethanol extract possesses analgesic, antiinflammatory and hypoglycaemic properties; and thus lend pharmacological support to folkloric, ethnomedical uses of ginger in the treatment and/or management of painful, arthritic inflammatory conditions, as well as in the management and/or control of type 2 diabetes mellitus in some rural Africa communities.”

Pine bark extract

Dehydroabietic acid Is a terpenoid contained in pine bark extract.  The 2009 paper Dehydroabietic acid, a diterpene, improves diabetes and hyperlipidemia in obese diabetic KK-Ay mice reports “In this study, the effects of dehydroabietic acid (DAA), a diterpene, on glucose and lipid metabolism were examined using obese diabetic KK-Ay mice. We showed here that DAA treatment decreased not only plasma glucose and insulin levels but also plasma triglyceride (TG) and hepatic TG levels. To examine the mechanism underlying the effects of DAA, the production of inflammatory cytokines was measured. It was shown that the DAA treatment suppressed the production of monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor-alpha (TNFalpha) (proinflammatory cytokines) and increased that of adiponectin (an anti-inflammatory cytokine). As a result of the changes in the production of inflammatory cytokines caused by the DAA treatment, the accumulation of macrophages in adipose tissues was reduced. These results indicate that treatment with DAA improves the levels of plasma glucose, plasma insulin, plasma TG, and hepatic TG through the decrease in the macrophage infiltration into adipose tissues, suggesting that DAA is a useful food-derived compound for treating obesity-related diseases.”

A final comment 

These two blog entries on diabetes have been very long – and I had to cut them off because I could have continued to go on and on citing more and more research publications .  There is one important message I hope to get across to my readers: There is a great deal of science  behind the lifestyle, dietary and supplement suggestions relating to prevention and control of diabetes, just as there is a great deal of science behind the other suggestions in the anti-aging lifestyle regimen and the combined anti-aging firewalls supplement regimen.

MEDICAL DISCLAIMER

FROM TIME TO TIME, THIS BLOG DISCUSSES DISEASE PROCESSES.  THE INTENTION OF THOSE DISCUSSIONS IS TO CONVEY CURRENT RESEARCH FINDINGS AND OPINIONS, NOT TO GIVE MEDICAL ADVICE.  THE INFORMATION IN POSTS IN THIS BLOG IS NOT A SUBSTITUTE FOR A LICENSED PHYSICIAN’S MEDICAL ADVICE. IF ANY ADVICE, OPINIONS, OR INSTRUCTIONS HEREIN CONFLICT WITH THAT OF A TREATING LICENSED PHYSICIAN, DEFER TO THE OPINION OF THE PHYSICIAN. THIS INFORMATION IS INTENDED FOR PEOPLE IN GOOD HEALTH.  IT IS THE READER’S RESPONSIBILITY TO KNOW HIS OR HER MEDICAL HISTORY AND ENSURE THAT ACTIONS OR SUPPLEMENTS HE OR SHE TAKES DO NOT CREATE AN ADVERSE REACTION.

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19. July 2010 by admin.

This is the first of two related blog posts on diabetes.  Here I review the nature of diabetes, and a commonly occurring biomolecular processes underlying the development of Type 2 diabetes.  I quote from several recent research papers relating diabetes to its closely-associated risk factors like obesity, metabolic syndrome and insulin resistance.  A Part 2 post will look at what research has to say relating the impacts on the underlying disease process of lifestyle activities and substances known to control diabetes.  That post will review lifestyle measures, dietary measures and supplements known to prevent or control diabetes.  A number of suggestions already in the anti-aging firewalls lifestyle regimen  and the combined supplement regimen are exactly ones that the research shows can avert or help control Type 2 diabetes. 

About Type 2 diabetes  Type 2 diabetes (diabetes mellitus) is the most common type representing about 90% of cases; it is a disease of high blood sugar connected with inability of cells to absorb sufficient glucose from the blood.  Insulin is required for such absorption and the problem can be either that the body does not produce sufficient insulin or, more likely, that the body cells cannot properly absorb the glucose due to insulin resistance(ref)(ref).  “Insulin resistance is a state in which a given concentration of insulin produces a less-than-expected biological effect. Insulin resistance has also been arbitrarily defined as the requirement of 200 or more units of insulin per day to attain glycemic control and to prevent ketosis. — The syndromes of insulin resistance actually make up a broad clinical spectrum, which includes obesity, glucose intolerance, diabetes itself, and metabolic syndrome, as well as an extreme insulin-resistant state. Many of these disorders are associated with various endocrine, metabolic, and genetic conditions. These syndromes may also be associated with immunological diseases and may exhibit distinct phenotypic characteristics(ref).” 

The excess blood sugar, in turn, can eventually lead to several disease conditions associated with diabetes including heart disease and stroke, high blood pressure, eye problems including cataracts, glaucoma, retinopathy and blindness, kidney damage. nerve damage, infections, gum disease, problems in pregnancy and dementia.Type 2 diabetes is traditionally viewed as a disease of aging, normally diagnosed in people 45 and over.  However it is increasingly being discovered in people of all ages including adolescents and children.

Risk factors for Type 2 diabetes include metabolic syndrome (itself a collection of risk factors for diabetes, heart disease and stroke — including abdominal obesity, high blood pressure, high blood sugar, low levels of “good” HDL cholesterol and high triglycerides, a sedentary lifestyle and insufficient exercise, obesity again, high-fat diet, and age over 45. Variations in some 38 genes have been identified with increased susceptibility to Type 2 diabetes(ref)(ref)(ref).  For example, see the blog post The “skinny” about the “fatso” gene FTO.

According to the American Diabetes Association “Data from the 2007 National Diabetes Fact Sheet (the most recent year for which data is available): Total: 23.6 million children and adults in the United States—7.8% of the population—have diabetes. Diagnosed: 17.9 million people, Undiagnosed: 5.7 million people,  Pre-diabetes: 57 million people,  New Cases: 1.6 million new cases of diabetes are diagnosed in people aged 20 years and older each year(ref).”  About 200 million people are directly affected worldwide.  Because of the dietary and lifestyle patterns that typically lead to Type 2 diabetes, it has sometimes been characterized as a disease of poverty(ref).Details of the multiple consequences of diabetes are grim.  They include vascular and cardiovascular problems, blindness dementia, loss of extremities, severe disability and premature death.    

According to the CDC, “If current trends continue, 1 in 3 Americans will develop diabetes sometime in their lifetime, and those with diabetes will lose, on average, 10–15 years of life. — Diabetes is the leading cause of new cases of blindness, kidney failure, and nontraumatic lower-extremity amputations among adults. –Diabetes was the sixth leading cause of death on U.S. death certificates in 2006. Overall, the risk for death among people with diabetes is about twice that of people without diabetes of similar age(ref).” 

The cost of diabetes to the U.S. in 2007 was $174 billion, according to the CDC.  Direct medical costs accounted for $116 billion, and indirect costs, such as disability, work loss and premature mortality, were listed at $58 billion. The biological and molecular roots of Type 2 diabetes In highly-simplified language the selected research publications quoted below as well as many other related publications provide the following picture:  In most cases of obesity there is a low level of inflammation in the white fat resulting in part from the in-migration of macrophages and resulting in the overproduction  of highly inflammatory cytokine molecules (adipokines) and overproduction of substances implicated in generating insulin resistance (e.g. resistin and leptin) and the underproduction of substances required for insulin sensitization (e.g. adiponectin).  Insufficient oxygen in the fat tissue due to lower capillary density in the fat tissue could source the inflammation and macrophage in-migration.  The result is an extensive re-organization of the adipose tissue and, too-often, insulin resistance, a chronic state of too-much sugar in the blood, and Type 2 diabetes.   This description is important because in the Part 2 blog post, I will characterize how certain of the lifestyle, dietary habits and supplements in the anti-aging firewalls regimens work on a molecular level to disrupt the described diabetes-creating process.  Note that there is both white fat where the insulin sensitivity problem initiates and “good” brown fat which accelerates metabolism and weight control.  See the blog entry Getting skinny from brown fat. Of the hundreds or thousands of research publications related to diabetes, I have selected a few that illustrate how obesity leads to Type 2 diabetes. 

An elegant explanation of how insulin resistance and diabetes can follow from a low-level inflammatory process present in obesity is given in the 2006 publication Recent advances in the relationship between obesity, inflammation, and insulin resistance.  “It now appears that, in most obese patients, obesity is associated with a low-grade inflammation of white adipose tissue (WAT) resulting from chronic activation of the innate immune system and which can subsequently lead to insulin resistance, impaired glucose tolerance and even diabetes. WAT is the physiological site of energy storage as lipids. In addition, it has been more recently recognized as an active participant in numerous physiological and pathophysiological processes. In obesity, WAT is characterized by an increased production and secretion of a wide range of inflammatory molecules including TNF-alpha and interleukin-6 (IL-6), which may have local effects on WAT physiology but also systemic effects on other organs. Recent data indicate that obese WAT is infiltrated by macrophages, which may be a major source of locally-produced pro-inflammatory cytokines. Interestingly, weight loss is associated with a reduction in the macrophage infiltration of WAT and an improvement of the inflammatory profile of gene expression. Several factors derived not only from adipocytes but also from infiltrated macrophages probably contribute to the pathogenesis of insulin resistance. Most of them are overproduced during obesity, including leptin, TNF-alpha, IL-6 and resistin. Conversely, expression and plasma levels of adiponectin, an insulin-sensitising effector, are down-regulated during obesity. Leptin could modulate TNF-alpha production and macrophage activation. TNF-alpha is overproduced in adipose tissue of several rodent models of obesity and has an important role in the pathogenesis of insulin resistance in these species. However, its actual involvement in glucose metabolism disorders in humans remains controversial. IL-6 production by human adipose tissue increases during obesity. It may induce hepatic CRP synthesis and may promote the onset of cardiovascular complications. Both TNF-alpha and IL-6 can alter insulin sensitivity by triggering different key steps in the insulin signaling pathway. In rodents, resistin can induce insulin resistance, while its implication in the control of insulin sensitivity is still a matter of debate in humans. Adiponectin is highly expressed in WAT, and circulating adiponectin levels are decreased in subjects with obesity-related insulin resistance, type 2 diabetes and coronary heart disease. Adiponectin inhibits liver neoglucogenesis and promotes fatty acid oxidation in skeletal muscle. In addition, adiponectin counteracts the pro-inflammatory effects of TNF-alpha on the arterial wall and probably protects against the development of arteriosclerosis. In obesity, the pro-inflammatory effects of cytokines through intracellular signaling pathways involve the NF-kappaB and JNK systems. Genetic or pharmacological manipulations of these effectors of the inflammatory response have been shown to modulate insulin sensitivity in different animal models. In humans, it has been suggested that the improved glucose tolerance observed in the presence of thiazolidinediones or statins is likely related to their anti-inflammatory properties. Thus, it can be considered that obesity corresponds to a sub-clinical inflammatory condition that promotes the production of pro-inflammatory factors involved in the pathogenesis of insulin resistance.” 

This paper has been widely cited and its findings confirmed.  For example, the 2007 publication Macrophage-specific PPARgamma controls alternative activation and improves insulin resistance reports on the same theme: “Obesity and insulin resistance, the cardinal features of metabolic syndrome, are closely associated with a state of low-grade inflammation. In adipose tissue chronic overnutrition leads to macrophage infiltration, resulting in local inflammation that potentiates insulin resistance. For instance, transgenic expression of Mcp1 (also known as chemokine ligand 2, Ccl2) in adipose tissue increases macrophage infiltration, inflammation and insulin resistance. Conversely, disruption of Mcp1 or its receptor Ccr2 impairs migration of macrophages into adipose tissue, thereby lowering adipose tissue inflammation and improving insulin sensitivity. These findings together suggest a correlation between macrophage content in adipose tissue and insulin resistance. — Using mice with macrophage-specific deletion of the peroxisome proliferator activated receptor-gamma (PPARgamma), we show here that PPARgamma is required for maturation of alternatively activated macrophages. Disruption of PPARgamma in myeloid cells impairs alternative macrophage activation, and predisposes these animals to development of diet-induced obesity, insulin resistance, and glucose intolerance. Furthermore, gene expression profiling revealed that downregulation of oxidative phosphorylation gene expression in skeletal muscle and liver leads to decreased insulin sensitivity in these tissues. Together, our findings suggest that resident alternatively activated macrophages have a beneficial role in regulating nutrient homeostasis and suggest that macrophage polarization towards the alternative state might be a useful strategy for treating type 2 diabetes.”  

The message in the 2010 publication Adipose tissue as an endocrine organ is completely consistent: “Obesity is characterized by increased storage of fatty acids in an expanded adipose tissue mass and is closely associated with the development of insulin resistance in peripheral tissues such as skeletal muscle and the liver. In addition to being the largest source of fuel in the body, adipose tissue and resident macrophages are also the source of a number of secreted proteins. Cloning of the obese gene and the identification of its product, leptin, was one of the first discoveries of an adipocyte-derived signaling molecule and established an important role for adipose tissue as an endocrine organ. Since then, leptin has been found to have a profound role in the regulation of whole-body metabolism by stimulating energy expenditure, inhibiting food intake and restoring euglycemia, however, in most cases of obesity leptin resistance limits its biological efficacy. In contrast to leptin, adiponectin secretion is often diminished in obesity. Adiponectin acts to increase insulin sensitivity, fatty acid oxidation, as well as energy expenditure and reduces the production of glucose by the liver. Resistin and retinol binding protein-4 are less well described. Their expression levels are positively correlated with adiposity and they are both implicated in the development of insulin resistance. More recently it has been acknowledged that macrophages are an important part of the secretory function of adipose tissue and the main source of inflammatory cytokines, such as TNFalpha and IL-6. An increase in circulating levels of these macrophage-derived factors in obesity leads to a chronic low-grade inflammatory state that has been linked to the development of insulin resistance and diabetes. These proteins commonly known as adipokines are central to the dynamic control of energy metabolism, communicating the nutrient status of the organism with the tissues responsible for controlling both energy intake and expenditure as well as insulin sensitivity.” 

The processes involved in inflammation of adipose tissue and consequent steps leading to insulin resistance and diabetes are complex involving many factors.  For example, adipose tissue may not receive sufficient oxygen as suggested in the 2009 publication Reduced adipose tissue oxygenation in human obesity: evidence for rarefaction, macrophage chemotaxis, and inflammation without an angiogenic response. “Compared with lean subjects, overweight/obese subjects had 44% lower capillary density and 58% lower VEGF, suggesting AT rarefaction (capillary drop out).” 

The 2010 publication Plasma adipokine and inflammatory marker concentrations are altered in obese, as opposed to non-obese, type 2 diabetes patients further amplifies the picture.  It would be possible to continue quoting other sources and generate a book on the subject, but that depth of treatment is not appropriate for this blog. 

What causes obesity in the first place?  The blog entry Obesity in the news again discusses the skyrocketing rate of obesity in the US and delves into that question.   Obviously, there are lifestyle factors like not moving much and eating a high-fat high-calorie diet and drinking a lot of sugar-infused sodas. Many biolgical factors can be involved like the abnormal expression of ghrelin, the “hunger protein.”  See the blog entry Ghrelin hunger, obesity and aging.  The metabolic pathways that can lead to obesity are also significant.  The AMPK pathway is particularly relevant to diabetes and metabolic syndrome.  See the subsection AMPK and Type 2 Diabetes in the recent blog post AMPK and longevity.  Finally, once there is an established state of metabolic syndrome or obesity, the changes brought about tend to lock in the metabolic syndrome or obesity through multiple channels.  Severely obese people may find it very difficult to exercise and experience abnormal hunger, for example.   

I have characterized a process of how Type 2 diabetes arises from obesity.  The characterization can also be applied where the problem arises in people with metabolic syndrome and large stomach paunches but who are otherwise lean.  In less-frequent cases such a when there is significant genetic susceptibility; type 2 diabetes also can arise in lean subjects through other processes too complex to cover here. 

Having in mind the pathological process through which diabetes arises from obesity or metabolic syndrome, the next blog entry, Diabetes Part 2: Lifestyle, dietary and supplemental interventions for diabetes will discuss research findings showing how the suggested interventions and certain diabetes medications interfere with the pathological process leading to diabetes. Please see the medical disclaimer for this blog.

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12. July 2010 by admin.

At the still-ongoing (as of July 12, 2010) meeting of the American Alzheimer’s Association in Honolulu, four different papers were presented that  validate components of the anti-aging firewalls regimen suggested in my treatise Anti-Aging Firewalls - The Science and Technology of Longevity and in previous blog entries including Diet and cognition, and Warding off Alzheimer’s Disease and things in my diet..  The regimen components concerned are exercise, drinking green tea and coffee, taking vitamin D and eating walnuts. “Evidence from three long-term, large-scale studies supports the association of physical activity and certain dietary elements (tea, vitamin D) with possibly maintaining cognitive ability and reducing dementia risk in older adults – (ref).”  The AAA papers listed here were embargoed for release until yesterday and can be found here.  I quote both from the papers and from the AAA ICAD press release. The highlights in italics of critical findings are my own.

The paper Physical Activity and the Risk of Dementia: The Framingham Study takes a longer-term look at the relationship between physical exercise and dementia than many of the earlier studies.  It draws its date from the Framingham Study, “a population-based study that has followed participants residing in the town of Framingham, Massachusetts since 1948 for cardiovascular risk factors, and is now also tracking cognitive performance. Framingham is widely acknowledged as a premier longitudinal study; it has continued to yield valuable information for more than 40 years(ref).”

“Zaldy Tan, MD, MPH, of Brigham and Women’s Hospital, GRECC, VA Boston, and Harvard Medical School, and colleagues estimated the levels of 24-hour physical activity of more than 1,200 elderly participants from the Framingham Study (742 female; age 76 +\-5) during the study’s 20th examination cycle (1986-87) and followed them for the development of dementia. They divided the participants into five groups based on level of physical activity, from lowest (Q1) to highest (Q5). — Over two decades of follow-up (mean 9.9 +/-5 years), 242 participants developed dementia (of which 193 were Alzheimer’s). The researchers found that participants who performed moderate to heavy levels of physical activity had about a 40 percent lower risk of developing any type of dementia. Further, people who reported the lowest levels of physical activity were 45 percent more likely to develop any type of dementia compared to those who reported higher levels of activity. Similar results were seen when analyses were limited to Alzheimer’s alone. Analyses showed that the observed associations were largely evident in men in the study.”

A 40% risk reduction for developing dementia due to physical activity alone is not bad, so keep moving and exercising.

The second study of concern is Tea, coffee and cognitive decline in the elderly: The Cardiovascular Health Study.  “Observational studies have shown associations between consumption of either tea or coffee and cognitive function in older adults, but data including long-term follow-up and rate of change in cognitive function are lacking. — Lenore Arab, PhD, of UCLA, and colleagues used data on more than 4,800 men and women aged 65 and older from the Cardiovascular Health Study to examine the relationship between consumption of tea, coffee, and change in cognitive function over time. Study participants were followed up for up to 14 years for naturally-occurring cognitive decline using the Mini-Mental State Examination (3MSE) administered at baseline and annually up to 8 times. People scored on the average 1.17 points less per year. Tea and coffee drinking were assessed using a food frequency questionnaire. — The researchers found that people who consumed tea at a variety of levels had significantly less cognitive decline (17-37 percent) than non-tea drinkers. More specifically, study participants who drank tea 5-10 times/year, 1-3 times/month, 1-4 times/week, and 5+ times/week had average annual rates of decline 17 percent, 32 percent, 37 percent, and 26 percent lower, respectively, than non-tea drinkers.  – According to the scientists, coffee consumption did not show any effect except at the very highest level of consumption – where it was associated with significantly decreased decline of 20 percent(ref).”

So, If you consume both large quantities of green tea and exercise, what is the reduction in dementia?  The question was not studied.  Does drinking tea bump up the AD risk reduction from 40% to 60% or 70%?

The third paper of concern is Vitamin D and Cognitive Impairment in NHANES III.  “3,325 adults aged 65 years or more completed cognitive assessments and provided blood samples in the Third National Health and Nutrition Examination Survey (NHANES III), a nationally representative cross-sectional study of the US non-institutionalized population. Cognitive impairment was assessed using measures of immediate and delayed verbal memory, orientation and attention (impairment was defined as the worst 10% of the distribution of combined scores).”   

“Recent European studies suggest vitamin D deficiency is associated with increased odds of cognitive impairment and dementia in later life, although previous findings from the U.S. have been mixed. Interest in vitamin D has intensified recently as research has suggested that it may play a role in a variety of age-associated diseases. — David Llewellyn, PhD, of the University of Exeter Peninsula Medical School (UK), and colleagues examined information from 3,325 adults aged 65 years and older from the Third National Health and Nutrition Examination Survey (NHANES III), a study that was carefully designed to accurately represent the U.S. non-institutionalized population. Vitamin D levels were measured from blood samples and compared with performance on a measure of general cognitive function that incorporated tests of memory, orientation in time and space, and ability to maintain attention. — The researchers classified participants as being cognitively impaired if they scored in the worst 10 percent of older adults in the study. They found that the odds of cognitive impairment were about 42 percent higher in those people who were deficient in vitamin D, and 394 percent higher in people who were severely deficient. –”It appears that the odds of cognitive impairment increase as vitamin D levels go down, which is consistent with the findings of previous European studies,” Llewellyn said. “Given that both vitamin D deficiency and dementia are common throughout the world, this is a major public health concern(ref).”

So if you exercise a lot, drink green tea and take vitamin D supplements, what is the combined reduction in your risk of getting Alzheimer’s disease?  Does it give you a 90% risk reduction for getting AD?  Again, this is a highly practical but unstudied question.

The final paper of concern is not a large-population study like the others; it is a mouse study: Walnuts-rich diet improves memory deficits and learning skills in transgenic mouse model of Alzheimer’s disease.”  Quoting the press release: “It has been suggested that oxidative stress may have a key role in Alzheimer’s disease. Oxidative stress occurs when the production of free radicals exceeds the antioxidant capacity of a cell. Reports have suggested that beta amyloid can increase oxidative stress leading to brain cell death. — Walnuts are source of a-linolenic acid (a plant-based omega-3 fatty acid) and have high content of antioxidants. In March 2004, the U.S. Food and Drug Administration said that “Supportive but not conclusive research shows that eating 1.5 ounces of walnuts per day, as part of a low saturated fat and low-cholesterol diet, and not resulting in increased caloric intake, may reduce the risk of coronary heart disease.”– Abha Chauhan, PhD, and colleagues at the New York State Institute for Basic Research in Developmental Disabilities, examined the effect of diet containing 6 percent or 9 percent walnuts (equivalent to 1 oz. and 1.5 oz. daily intake of walnuts in people) on the cognitive, emotional and motor functions in a transgenic mouse model of Alzheimer’s. The mice were fed custom-mix diets from the age of four months for nine to 15 months. Control mice were fed diet without walnuts. The experimental and control mice were examined at the age of 13 to 14 months and 18 to 19 months for spatial memory and learning ability, position discrimination learning ability, motor coordination, and anxiety-related behavior. — The researchers found that Alzheimer’s transgenic mice on the diet without walnuts at both testing periods showed memory deficits, anxiety-related behavior, and severe impairment in spatial learning ability, position discrimination learning ability and motor coordination. The Alzheimer’s transgenic mice on 6 percent walnuts diet and 9 percent walnuts diet showed significant improvement in learning, memory, emotional regulation and motor coordination compared to transgenic mice that did not eat walnuts. The effects of 6 percent and 9 percent walnuts diets were similar.”

So then, what is the impact on dementia risk reduction if older folks like me  pursue all four interventions simultaneously: regularly exercise, drink green tea, take vitamin D3 and eat walnuts daily? How about also pursuing a Mediterranean diet and eating bitter dark chocolate snacks(ref)(ref)?  And what would be the impacts of also taking the other anti-oxidant and dietary polyphenols in the combined combined supplement regimen and pursuing the other lifestyle regimen suggestions in my treatise and blog entries related to avoiding dementia?  I conjecture that the probable benefits are highly synergistic and far exceed those of any of the individual interventions described in the papers reported here.   

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10. July 2010 by admin.

I have written about developments relating to cell reprogramming and induced pluripotent stem cells (iPSCs) in several previous blog posts, the most recent including A near-term application for iPSCs – making cell lines for drug testing, Induced pluripotent stem cells – second-rate stem cells so far, and Direct cell reprogramming.

Converting a scientific discovery into a practical technology always requires a number of secondary scientific discoveries and engineering developments –not basic breakthroughs but development of approaches that eliminate practical barriers and reduce costs.  It also requires mobilization of financial and business resources.  This blog post is concerned with three such current developments relating to iPSCs.

iPSCs from blood cells

It has long been known that practically any cell type can be reverted to iPSC status but, practically speaking, human iPSCs have almost always generated from fibroblasts.  Two of the barriers associated with producing  human iPSCs so far have therefore been 1.  The fibroblasts must be obtained from donors using a minor surgical procedure like a biopsy, limiting supply and raising cost, and 2.  The process of reversion of fibroblast cells to iPSCs takes a long time, around a month, and during this time mutations can accumulate.

Three new papers in the July 2 issue of Cell Stem Cell report on techniques for obtaining iPSCs from blood samples.  The blood can come from needle sticks, blood banks or umbilical cords of newborn. “In this issue of Cell Stem Cell, Staerk et al. (2010), Seki et al. (2010),  and Loh et al. (2010) each describe the derivation of human iPSCs from peripheral blood. Although seemingly incremental, this advance brings the stem cell field an important step closer to eventual clinical use.” 

The July 2010 paper Reprogramming of Human Peripheral Blood Cells to Induced Pluripotent Stem Cells explains the benefits of the process.  “The generation of patient-specific pluripotent cells is therefore an important goal of regenerative medicine. A major step to achieve this was the recent discovery that ectopic expression of defined transcription factors induces pluripotency in somatic cells (Lowry et al., 2008,Park et al., 2008b,Takahashi et al., 2007,Yu et al., 2007). Until now, the most common source from which to derive human iPSCs has been skin fibroblasts (Lowry et al., 2008,Park et al., 2008a,Park et al., 2008b,Takahashi et al., 2007,Yu et al., 2009). However, the requirement for skin biopsies and the need to expand fibroblast cells for several passages in vitro represent a hurdle that must be overcome to make iPSC technology broadly applicable. Peripheral blood can be utilized as an easily accessible source of patient tissue for reprogramming. Here we derived iPSCs from frozen human peripheral blood samples. Some of the iPSCs had rearrangements of the T cell receptor (TCR), indicating that T cells can be reprogrammed to pluripotency.– Our study demonstrates that peripheral blood can be utilized as an easily accessible source of patient tissue for reprogramming without the need to extensively maintain cell cultures prior to reprogramming experiments. This is an important step to make the iPSC technology more broadly applicable. Importantly, reprogramming of peripheral blood samples will permit access to numerous frozen samples already stored at blood banks. These samples are often of restricted use for research, because limited cell numbers do not allow experimental manipulations. This is particularly relevant if the patient is deceased and new material cannot be obtained. Generation of iPSCs from such samples could provide cell numbers large enough to retrospectively screen for genetic factors and to study molecular mechanisms underlying myeloid and lymphoid blood disorders.” 

The reversion process was not simple, however. “To increase the infection efficiency, we used a doxycycline-inducible lentivirus encoding all four factors Oct4, Klf4, Sox2, and c-Myc from a polycistronic expression cassette (pHAGE2-TetOminiCMV-hSTEMCCA) (Sommer et al., 2010). Blood cells were simultaneously infected with a constitutively active lentivirus encoding the reverse tetracycline transactivator (FUW-M2rtTA) (Hockemeyer et al., 2008) as well as the polycistronic vector. Infected blood cells were transferred onto feeder layers of mouse embryonic fibroblasts (MEFs) and cultured in the presence of IL-7 or G-CSF, GM-CSF, IL-6, and IL-3 and 2 g/ml doxycycline (Dox) for an additional 4 days (Figure 1A). At day 5 after Dox induction, the cells were transferred to human ESC medium containing 2 g/ml Dox, and 25 40 days later colonies were picked and expanded(ref).”

The second July 2010 paper in the same journal  issue Generation of Induced Pluripotent Stem Cells from Human Terminally Differentiated Circulating T Cells describes the approach used.  As in the case of the first paper, the iPSCs are mainly derived from blood T cells. “To avoid transgene integration during iPSC generation, we used an SeV vector, which is a minus-strand RNA virus that is not integrated into the host genome and is not pathogenic for humans (Li et al., 2000). We used a temperature-sensitive mutated SeV vector in these experiments to reduce transgene expression and SeV residue in generated lines. — To generate iPSCs from hTDCTCs, we used SeV to deliver multiple transgenes that encoded stem cell-specific transcription factors, such as OCT3/4, SOX2, KLF4, and c-MYC, into cells on day 6 of culture.”

The third paper in the same July 2010 issue of Cell Stem Cell, Reprogramming of T Cells from Human Peripheral Blood, reports “To test whether we can reprogram cells from routine peripheral blood (PB) sources, we obtained CD34⁺ purified blood samples from a healthy 49-year-old male donor who had undergone simple apheresis without cytokine priming. We also isolated mononuclear cells (PBMCs) from the peripheral blood samples collected by venipuncture of four healthy donors (28- to 49-years-old) via Ficoll density centrifugation. — To induce reprogramming of enriched CD34⁺ blood cells, we infected with lentiviruses expressing OCT4, SOX2, KLF4, and MYC reprogramming factors (Figure 1A). Colonies with well-defined hESC-like morphology were first observed 21 days after transduction (Figure 1B). For reprogramming of fresh peripheral blood mononuclear cells (PBMCs), we employed two rounds of lentiviral infection (day 0 and day and isolated colonies with distinct flat and compact morphology with clear-cut round edges reminiscent of hESCs after a slightly longer latency of around 35 days (Figure 1C). With immunohistochemistry and flow cytometry, we analyzed the iPSC lines for expression of markers shared with hESCs. Consistent with their hESC-like morphology, both PB34 iPSCs and PBMC iPSCs stained positive for Tra-1-81, NANOG, OCT4, Tra-1-60, SSEA4, and alkaline phosphatase (AP) staining (Figures 1B 1D; Figures S1 A S1C available online; Chan et al., 2009).”

Reprogramming efficiency, already low for fibroblasts, is even worse using ordinary blood.  “We routinely observed a reprogramming efficiency of 0.002% for PB CD34⁺ cells (Table S1 ), comparable to prior experience with primary fibroblasts, mobilized PBMCs, and cord blood cell reprogramming (Takahashi et al., 2007,Park et al., 2008a,Loh et al., 2009,Haase et al., 2009). For PBMCs, we obtained hESC-like colonies at the lower efficiency of 0.0008% 0.001% (Table S1 )(ref).  This low reprogramming efficiency is yet-another problem that has to be solved before blood can routinely used instead of fibroblasts to produce iPSCs.

iPSCs and Mesenchymal-to-Epithelial Transition

Despite the fact that several groups of researchers have routinely been generating iPSCs for more than a couple of years now, exactly how the transcription factors like  OCT4, SOX2, c-MYC, and Klf4 work on a molecular basis to reset the epigenomic state of cells to a pluripotent basis has remained largely a mystery. Some light is shed on that issue by two papers published this month on the role of mesenchymal-to-epithelial transition (MET) in cell reprogramming.

One of the July 2010 papers is A Mesenchymal-to-Epithelial Transition Initiates and Is Required for the Nuclear Reprogramming of Mouse Fibroblasts. “Epithelial-to-mesenchymal transition (EMT) is a developmental process important for cell fate determination. Fibroblasts, a product of EMT, can be reset into induced pluripotent stem cells (iPSCs) via exogenous transcription factors but the underlying mechanism is unclear. Here we show that the generation of iPSCs from mouse fibroblasts requires a mesenchymal-to-epithelial transition (MET) orchestrated by suppressing pro-EMT signals from the culture medium and activating an epithelial program inside the cells. At the transcriptional level, Sox2/Oct4 suppress the EMT mediator Snail, c-Myc downregulates TGF-β1 and TGF-β receptor 2, and Klf4 induces epithelial genes including E-cadherin. Blocking MET impairs the reprogramming of fibroblasts whereas preventing EMT in epithelial cells cultured with serum can produce iPSCs without Klf4 and c-Myc. Our work not only establishes MET as a key cellular mechanism toward induced pluripotency, but also demonstrates iPSC generation as a cooperative process between the defined factors and the extracellular milieu.”

The other July 2010 paper is Functional Genomics Reveals a BMP-Driven Mesenchymal-to-Epithelial Transition in the Initiation of Somatic Cell Reprogramming. “Somatic cells can be reprogrammed to induced pluripotent stem cells (iPSCs) by expression of defined embryonic factors. However, little is known of the molecular mechanisms underlying the reprogramming process. Here we explore somatic cell reprogramming by exploiting a secondary mouse embryonic fibroblast model that forms iPSCs with high efficiency upon inducible expression of Oct4, Klf4, c-Myc, and Sox2. Temporal analysis of gene expression revealed that reprogramming is a multistep process that is characterized by initiation, maturation, and stabilization phases. Functional analysis by systematic RNAi screening further uncovered a key role for BMP signaling and the induction of mesenchymal-to-epithelial transition (MET) during the initiation phase. We show that this is linked to BMP-dependent induction of miR-205 and the miR-200 family of microRNAs that are key regulators of MET. These studies thus define a multistep mechanism that incorporates a BMP-miRNA-MET axis during somatic cell reprogramming.” This paper indicates that expression profiling reveals three phases of cell reprogramming: an initiation phase where MET plays a major role, a maturation phase and a stabilization phase.  “ RNAi screening defines MET and BMP signaling as essential for reprogramming. BMP induces miR-200 family miRNAs to drive MET and somatic cell reprogramming(ref).”

Another-yet current paper that relates MET to Snail is Notch mediated epithelial to mesenchymal transformation is associated with increased expression of the Snail transcription factor.

Commercial exploitation of iPSCs to discover drugs

In the blog post A near-term application for iPSCs – making cell lines for drug testing I stated “There is another application for iPSCs which is likely to become very important in the immediate future: supplying large quantities of specialized body cells for research and drug testing purposes.”  Further, I discussed how a company called Cellular Dynamics International was setting out to produce human iPSC-derived cardiomyocytes on a substantial scale and market them for research and drug-testing purposes. 

Here I report on the activities of another new company, iPierian, which has just closed on $22 million of series b financing led by Google Ventures. “The company is developing and applying cellular reprogramming and differentiation technologies to harness the power of pluripotent stem cells to transform drug discovery and enable the promise of regenerative medicine. iPierian’s induced pluripotent stem (iPS) cell technology will advance the understanding of disease biology and make drug discovery and development faster and better informed. — iPierian plans to apply this revolutionary technology in its proprietary programs and leverage it in collaborations with pharmaceutical and biotechnology industry partners. The company’s reprogramming and differentiation technologies will enable the identification of promising new therapeutic candidates earlier in the drug discovery process. Through its efforts, iPierian expects to make pharmaceutical research more directly beneficial to patients and more cost-effective for its partners.”

iPierian is the result of the merger of two companies involving an impressive collection of individuals.  ”One, in Boston, was called Pierian, co-founded by George Daley, Doug Melton and Lee Rubin, a trio of stars from the Harvard Stem Cell Institute. The other, iZumi Bio, in Mountain View, CA, had the entrepreneurial leadership of Corey Goodman as chairman, and John Walker, a longtime director of stem cell pioneer Geron, as CEO. The merged operation boasts a blue chip crew of backers—Kleiner Perkins Caufield & Byers, Highland Capital, MPM Capital, and FinTech Global Capital, who have pumped in a combined $31.5 million(ref).”

“It’s more about using the power of stem cells to discover new drugs, so that iPierian can find treatments that no one ever could before because they were constrained by limited tools. iPierian has set its sights from the start on neurodegenerative diseases that really have no good treatments—like Lou Gehrig’s disease, Huntington’s disease, and eventually Parkinson’s and Alzheimer’s. The cells, with all their talent to morph into any kind of adult cell scientists want, won’t get injected into the patient to replace missing or damaged tissue. Instead, they could help the scientists gather new insights into these intractable diseases, speed up the development process, and save time. Then iPierian will use all of this information to make conventional small molecule pills, or injectable protein drugs. If it is successful, the patients wouldn’t even know it was because of stem cells(ref).”

“iPierian’s efforts are centered on applying its technology to diseases for which there are poor in vivo and in vitro models and limited therapeutic treatments to date. iPierian’s proprietary programs are initially focused on three neurological diseases, including Parkinson’s disease, spinal muscular atrophy and amyotrophic lateral sclerosis. These conditions have limited therapeutic treatments, and scientists have demonstrated the ability to differentiate the affected cell types in these disorders. — iPierian is also working on calcific aortic valve disease, through its collaboration with the Gladstone Institute of Cardiovascular Disease, and plans to expand further into cardiovascular and metabolic diseases through additional collaborations with pharmaceutical partners(ref).” 

The launching of iPierian is another example of how scientific, technical, economic and business factors are cooperating to ever-quicken the pace of discovery and make anti-aging breakthroughs more likely, a phenomenon I discussed in the blog post Factors that drive Giuliano’s Law.

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6. July 2010 by admin.

Longevity science had been a hobby for me for a long time and about 3 years ago I decided to pursue it as a new full-time career.  I put the first version of my treatise Anti-Aging Firewalls - The Science and Technology of Longevity online in May 2008 and started this blog in January 2009.  This blog entry is about how my some of thoughts relating to longevity science have evolved during that period.

These thoughts are in addition to those in the January 21 2010 blog entry The evolution of this blog.  At that time I was logging 700 to 1,000 unique visits a day, different people who stayed to read 2 or more web pages.   Now, 6 months later, I am typically logging between 1,100 to 1,800 unique visits a day.  Interestingly, I have recently been getting a lot of visits from Russia.

From the onset I was determined to take a broad view of longevity science rather than to focus on one or the other of the many pet theories out there.  I was also interested in identifying any actionable steps older people like me could take to live longer and more healthily.  So, I set out in my treatise to examine the main theories of aging.  My initial approach was logical.  I would identify what the major theories of aging are and then, for each theory, identify to the extent possible a “firewall” of lifestyle, dietary and dietary supplement steps that would be protective against aging according to that theory.  My information would come from perusal of published research information and I would avoid repeating unsubstantiated information or opinions from non-professionals or commercial sites.

By the time I first went online with the treatise in May 2008, I had pursued this approach for the first 12 theories of aging dealt with in my treatise:

1.     Oxidative Damage

2.     Cell DNA Damage

3.     Mitochondrial Damage

4.     Tissue Glycation

5.     Lipofuscin Accumulation

6.     Chronic Inflammation

7.     Immune System Compromise

8.     Neurological Degeneration

9.     Declines in Hormone Levels

10.                        Susceptibility to Cancers

11.                        Susceptibility to Cardiovascular Disease

12.                        Telomere Shortening and Damage

Within the next six months I realized that to these classical theories of aging I needed to add two newer theories:

13.                        Programmed Epigenomic Changes and

14.                        Stem Cell Supply Chain Breakdown

I have continued to refine my description of these as time progresses and believe that the Stem Cell Supply Chain Breakdown theory of aging is original with me.  Later I went on to identify an additional six possible “candidate” theories of aging:1.     Incorrect protein folding, 2.     Accumulation of progerin, 3.     Gene mutations leading to hellicase abnormalities, 4.     Increasing mTOR signalling, 5.     Declining hypoxic response, and 6.     Micronutrient triage with aging.

Further I developed few key insights about the theories:

1.  it is possible to keep on adding more theories of aging; the next two could be    Metabolic degradation affecting the expression of sirtuins(ref)(ref), and Decline in effectiveness of autophagy(ref), 

2.  beyond anti-aging interventions for the first 12 theories, there seemed to be few if any additional interventions I could suggest for the other theories, and

3. The “theories” of aging might better be called corollaries or concomitants of aging because with the exceptions of 13 and 14 they are far too specialized and incomplete to describe aging.  Each of the theories relates to phenomena that can and often do happen during aging and that can accelerate aging when they occur.  However, aging itself is a systems process involving the processes of all of the theories. 

Think of it this way.  If one asks “What causes an automobile to move?” valid answers could include “The tires, the wheels, the transmission, the engine, the internal combustion of gasoline, the gear train” and many others.  All are valid answers but if you are really concerned about how an automobile works you have to look at it as a complex system where each part has its own function and all are needed.  The same holds for the body and aging, a system vastly more complex than an automobile.

After launching this blog in January 2009 I started writing about gene-activation pathways, molecular activator and co-activator substances, types and properties of stem cells and other topics that I previously knew nothing or next to nothing about.  It became apparent that there was a growing list of complicated topics related to molecular biology, genetics, epigenetics and other advanced sciences that have a lot to do with longevity.  So, I started to research and write about these.  The list of these advanced topics is already long staring with NF-kappaB, P21,  P16/ink4a and mTOR, DHMEQ,  Nrf2, ALPHA-msh, DNA repair strategies the NRG1 gene  and moving on to include iPSC stem cells, SIRT-1 and DNA methylation and histone actetylation.  In recent weeks advanced topics have included the ghrelin and humanin proteins, the AMPK pathway and the HSP70 heat shock protein family. 

New bodies of science highly relevant to aging have been assuming importance during my three years of study: epigenetics, epigenomics, proteomics, transcriptomics, nutrigenomics, and many others.  I have also reported from time to time on these.   

So, as time has progressed I have been learning and sharing a lot more about advanced topics in longevity science.  At the same time I have explored deeper into the original theories of aging and practical anti-aging interventions.  I have written posts on the benefits of blueberries, spices, extra-virgin olive oil and other foods and on exercise, for example.  I have written posts on age-related diseases such as Alzheimer’s, auto-immune diseases, cancers like melanoma and lymphoma, and HIV for example.  I have described the growing number of new association studies that are linking genetic and epigenetic states to disease susceptibilities.  The list goes on and on.  As of now this blog includes 296 substantive posts and 512 comments. 

To put it simply, I have been learning a lot about the sciences behind aging. I have devoted thousands of hours to studying the literature of aging science, thinking about various topics and writing these blog posts.  And recently I have been going to conferences on aging and I have had personal discussions with some of the giants in the field.

How have my viewpoints changed as a result of that intensive educational process?  Here are some observations: 

·        Aging is a much more complicated process than I thought it would turn out to be and still very poorly understood.  Multiple interacting body systems are involved and the areas of science that will really help aging are just barely getting off the ground: epigenetics and epigenetic-epigenomic regulation and the life-cycle of the stem cell supply chain(ref).   

·        What we have learned we don’t yet know relating to these areas has grown exponentially compared to what we have actually learned.  I personally know a great deal more now about aging science than I knew three years ago.  But I now see there are vast relevant areas where knowledge is scanty or nonexistent, like the vast areas on ancient maps marked “Hic sunt dracones” (Here there be dragons).  Three years ago I was oblivious to the existence of these areas.   And I am sure that as those areas are explored, the presence of even vaster relevant areas beyond them will be discovered. 

·        There is no simple “magic bullet” in sight for radical life extension, a pill or process that will allow even a few of us humans to live beyond the 122 years known life-limit for humans.  There is not even speculation about what such an approach would look like in the aging research literature.  This has been a disappointment to me since when I started out I thought telomere extension via telomerase activation might do the trick.   I was quite naïve at the time and currently question whether telomerase activation is of any lasting value.  See the recent post on Stress, exercise and telomere lengths.  Nonetheless I have not given up on the idea of radical life extension and remain keenly on the lookout for research clues as to how it might be created.  I expect something new and basic relating to this possibility to show up in the next 3 years.

·        On the other hand, I have learned that there is solid evidence that a few known genetic pathways and possible intervention strategies might conceivably allow us to extend our average lifespans and healthspans by as much as 15% to 20%.  These strategies include inhibition of mTOR, activation of AMPK, activation of SIRT1, activation of telomerase, and possibly combinations of these. 

·        Life extension seems to be the same as extension of healthspan when considering these strategies.  In animal models of life extension the same diseases and problems of old age still occur but they occur later in life.

·        Life extension can occur through postponing or curing diseases of old age, so the science of Alzheimer’s disease, of diabetes and of the other killer diseases of old people is part and parcel of the science of longevity.  Predictive, personalized proactive medicine based on early identification of disease biomarkers is likely to have a strong positive impact on lifespans in the coming two decades.

·        Surprising benefits in healthspan and life extension can probably be realized via adopting healthy conventional-wisdom lifestyle patterns, diet and taking dietary supplements – again, perhaps 15%.  See for example Stress, exercise and telomere lengths, Back to blueberries,  Calorie restriction mimetics - focus on avocado extract, Extra-virgin olive oil.  And of course, see the lifestyle regimen section of my treatise.

·        Even a 15% increase in healthspan and lifespan across the population in an advanced country like the US would be of incredible value, worth trillions of dollars in increased productivity(ref).

·        Additional ways in which my thinking about aging has changed are described in the recent blog post What are aging, life-extension and anti-aging? In that post I comment on the difference between interventions that extend lives and ones that combat the biological process of aging.  Healthier diets that lead to less obesity, for example, can extend lives without tinkering with the intrinsic aging process.

·        I plan to continue writing blog entries on complex topics relating to aging, at least until I feel sure I have covered all the important ones.  I will report on current research amplifying or extending our understanding of topics I have written about before.  And I will sometimes delve deeper into topics already discussed.  So, the tendency of the blog to become more technical may well continue.

·        You can count on me always to write in a context respecting scientific integrity.  As always I will frequently quote directly from research citations and make sure that, when I am expressing my own opinion, that is clear.  I have no commercial affiliations and do not accept advertising.

·        This blog and my treatise are already well on their way to being a comprehensive and constantly updated compendium of knowledge, research information and citations regarding the science of aging.  I want to continue on that track.

A speculation on a chain of future developments

One very bright area related to longevity science is the development of infrastructure such as capability for genome sequencing and genomic/epigenomic databases.  Improvements in sequencing (genomic, epigenomic, proteomic, etc.) technology have followed Moore’s Law - price-performance doubles every two years.  These infrastructure elements allow continuing acceleration in the rate of new discoveries relevant to aging.  

I suspect sequencing will continue to follow a path like the computer industry did.  When I started this journey three years a, I compared the field of aging science to the field of computer science in 1955.  Now the sophistication of longevity science and engineering is perhaps up to about the levels for computers in 1958, when the very-first large mainframe computers were coming on the market.  These massive 10-million dollar computers were orders of magnitude more powerful than 1952 computers, but had only a very tiny fraction of the power and capability of the Blackberry smartphone I carry everywhere on my belt. 

Today, powerful advanced “next-gen” tabletop gene sequencers are available while formerly they filled entire rooms like early computers did. Today it costs about $6,000 to sequence the entire genome of an individual and the figure will soon be less than $1,000, down from a cost of over a hundred million dollars only about 10 years ago.   

What can happen if sequencing continues to go the way computers did?  Here is a speculation.  Before 2017, personal multifunction sequencers will become available – small units the size of PCs that will allow members of a family not only to sequence their personal genomes but also to some extent monitor the states of their epigenomes.  By then a large number of genomic/epigenomic markers should be available indicating increased susceptibilities to many diseases that worsen with aging.  The early warnings will allow corrective actions to be taken before actual disease states set in.  Like having a radar in an airplane, the sequencer will allow people to see the storm clouds of a disease coming and in many cases fly around them.  By 2020 the software in these units will allow more sophisticated testing and offer day-to-day monitoring  of problems and suggest corrective actions.  The units will link online to large genomic/epigenomic databases and to people’s physicians and health providers.  People will start buying these units in large quantities like they were buying PCs in the early 1990s. 

By 2025 the sequencer-monitor units will be far more capable, will be smaller than a hearing aid, will be unobtrusive and routinely worn, and will offer hour-to-hour monitoring of a large number of body conditions as well as epigenetic state.  The unit will communicate wirelessly with health resources and, in case of emergencies the unit will signal wirelessly for help indicating the nature of the emergency. 

While this speculative scenario may seem a fantasy, it is just a replay of what has been happening with smart cell phones and computers.  The microtechnology required for all of this to happen basically exists.  What is needed to get this process going is the development of an initial product, starting to build a market, ever-better biomarkers, personal-sequencer software and constant lowering of cost that can only come with economy of scale.

Many hoped-for approaches to longevity have not turned out to be going as well as I hoped they would be, but other unforeseen developments are quite positive.  Armed with ever-increasing sophistication, I am continuing on the journey and quest to learn more about aging and how to retard or reverse it.  I will document all possibly relevant discoveries in this blog.  So please stay tuned.  I most value your feedback.

The evolution of my own health during the last 3 years is another issue I will take up in a different blog entry.

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3. July 2010 by admin.

Hormesis is a process through which moderate stress induces a body response that is protective against insults, confers health and possibly even longevity benefits.  The process of hormesis is thought to be mediated primarily via heat shock proteins (HSPs).  An introduction to these topics is provided in the blog entry Hormesis and age retardation.  Also, see my blog entry Stress and longevity for a further discussion of how moderate stresses confer longevity.  In this blog entry I thought I would further explore how hormesis and heat shock proteins work, focusing primarily on the HSP70 superfamily of proteins.  Frankly, I was shocked (sort of by intellectual heat) to discover the complexity of the biomolecular processes involved and gave up on the process a few times until I finally decided to dig into it.  In this blog entry I will attempt a simplified explanation of how hormesis and the HSP70 chaperone proteins work to exercise their health benefits.  Even simplified the topic is still complex, so please fasten your mental seat belts.

First of all, heat stress, oxidative stress and other kinds of stress can cause the improper unfolding of proteins in the endoplasmic reticulum in cells.  “Proteins in the endoplasmic reticulum (ER) require an efficient system of molecular chaperones whose role is to assure their proper folding and to prevent accumulation of unfolded proteins,  triggering what is known as the “unfolded protein response” (UPR). UPR is a functional mechanism by which cells attempt to protect themselves against ER stress, resulting from the accumulation of the unfolded/misfolded proteins.” The quote is from the 2004publication Endoplasmic Reticulum Stress and Unfolded Protein Response in Inclusion Body Myositis Muscle.

The UPR is an ancient response shared among many living things.  “The unfolded protein response (UPR) is a cellular stress response — that has been found to be conserved between all mammalian species, as well as yeast and worm organisms.   The UPR is activated in response to an accumulation of unfolded or misfolded proteins in the lumen of the endoplasmic reticulum. In this scenario, the UPR has two primary aims: initially to restore normal function of the cell by halting protein translation (genetics) and activate the signaling pathways that lead to increasing the production of molecular chaperones involved in protein folding. If these objectives are not achieved within a certain time lapse or the disruption is prolonged, the UPR aims to initiate programmed cell death (apoptosis)(ref).”  While you are at it, by the way, you might want to check out The Incorrect protein folding theory of aging discussed in my treatise.  The basic notion is that stress often leads to the misfolding of proteins, a process that can accelerate with age creating dysfunctional conditions and vulnerability to a number of diseases.  Misfolded proteins cannot perform their intended functions and can create active mischief.  In a nutshell, the role of the HSP70 heat shock proteins is to mobilize when large numbers of misfolded proteins show up due to stress, and to fold them up properly again.  So, HSP70 proteins play important roles in health maintenance and possibly also in longevity.

On a macroscopic level HSP70 proteins are known to play a number of important roles.  See for example the 2008 paper Inducible heat shock protein 70 and its role in preconditioning and exercise.  “Preconditioning has been shown to confer cellular protection via expression Hsp, which may be of benefit in preventing protein damage following subsequent periods of exercise.”  The 2002 review paper Neuroprotection: heat shock proteins states “This chapter highlights the involvement of HSP70 involvement in the pathophysiology of cerebral ischaemia, from the original reports of HSP70 expression after cerebral ischaemia to evidence of HSP70 neuroprotection and the potential mechanisms which might mediate this cellular protection.” 

 The neuroprotective mechanisms of HSP70 are multiple as is pointed out in the 2002 review publication Heat shock proteins and neuroprotection.  “In response to many metabolic disturbances and injuries including stroke, neurodegenerative disease, epilepsy and trauma, the cell mounts a stress response with induction of a variety of proteins, most notably the 70 kD heat shock protein (Hsp70). The possibility that stress proteins might be neuroprotective was suspected because Hsp70, in particular, was induced to high levels in brain regions that were relatively resistant to injury. Hsp70 expression was also correlated with the phenomenon of induced tolerance. With the availability of transgenic animals and gene transfer, has it become increasingly clear that such heat shock proteins do indeed protect cells from injury. Several reports have now shown that selective overexpression of Hsp70 leads to protection in several different models of nervous system injury. This review will cover these studies, along with potential mechanisms by which Hsp70 might mediate cellular protection.” 

HSP70 is of course only one of several heat shock protein families.  Other HSP proteins may exercise similar or complimentary effects.  The example, HSP90 is discussed in the 2010 publication Heat shock protein 90 in neurodegenerative diseases.

The 2004 publication Many mechanisms for hsp70 protection from cerebral ischemia tells “In addition to the well-studied role of Hsp70 as a molecular chaperone assisting in correct protein folding, several new mechanisms by which Hsp70 can prevent cell death have been described. Hsp70 is now known to regulate apoptotic cell death both directly by interfering with the function of several proteins that induce apoptotic cell death as well as indirectly by increasing levels of the anti-death protein bcl-2. Despite these new insights into the ways in which Hsp70 functions as an anti-death protein, further surprises are likely as we continue to gain insight into the functioning of this multifaceted protein.”

The HSP70 superfamily consists of multiple members, and each member seems to have distinct properties in terms of structure, cellular localization, function and response to stress(ref).   “In humans, 17 genes for the HSP superfamily are grouped into the HPS110 family and the HSP 12 family(ref).”  And these families in turn have identified subfamilies.  The functions of the HS{70 superfamily proteins are regulated and/or modified by co-chaperones, particularly in the J-family and in the BAG family.  Again, the pathways appear to be ancient and conserved across a variety of species and the interactions are complex and in several cases not well understood.

Much of our limited knowledge of what goes on comes from study of what goes on in other much-simpler species, an example being the ascidian Ciona intestinalis.  See the 2010 publication Stress response in the ascidian Ciona intestinalis: transcriptional profiling of genes for the heat shock protein 70 chaperone system under heat stress and endoplasmic reticulum stress.  .  “Most stress-inducible genes are conserved between Ciona and vertebrates, as expected from a close evolutionary relationship between them. The present study characterized the stress responses of HSP70 chaperone system genes in Ciona for the first time and provides essential data for comprehensive understanding of the functions of the HSP70 chaperone system.”

How do HSP70s basically work?  The 2005 paperThe 2005 paper HSP70 chaperones: cellular functions and molecular mechanism has this to say: “Hsp70 proteins are central components of the cellular network of molecular chaperones and folding catalysts. They assist a large variety of protein folding processes in the cell by transient association of their substrate binding domain with short hydrophobic peptide segments within their substrate proteins. The substrate binding and release cycle is driven by the switching of Hsp70 between the low-affinity ATP bound state and the high-affinity ADP bound state. Thus, ATP binding and hydrolysis are essential in vitro and in vivo for the chaperone activity of Hsp70 proteins. This ATPase cycle is controlled by co-chaperones of the family of J-domain proteins, which target Hsp70s to their substrates, and by nucleotide exchange factors, which determine the lifetime of the Hsp70-substrate complex. Additional co-chaperones fine-tune this chaperone cycle. For specific tasks the Hsp70 cycle is coupled to the action of other chaperones, such as Hsp90 and Hsp100.”

Most of the studies related to HSP70 appear to be highly focused and related to strange species far removed from humans, for example 2010 study Molecular cloning and expression of two HSP70 genes in the Wuchang bream (Megalobrama amblycephala Yih), the 2007 publication An inducible 70 kDa-class heat shock protein is constitutively expressed during early development and diapause in the annual killifish Austrofundulus limnaeus the 2004 study Expression of cytoprotective proteins, heat shock protein 70 and metallothioneins, in tissues of Ostrea edulis exposed to heat and heavy metals, and Sequencing and expression pattern of inducible heat shock gene products in the European flat oyster, Ostrea edulis and the 2008 study Inducible and constitutive heat shock gene expression responds to modification of Hsp70 copy number in Drosophila melanogaster but does not compensate for loss of thermotolerance in Hsp70 null flies.  It is very challenging, to say the least, to draw together the conclusions of these studies into a coherent picture relevant to humans except that, mostly but not always, “a phylogenetic analysis of the HSP70 family members from oyster and other bivalves revealed a substantial conservation in the evolutionary pattern among constitutive and inducible gene products, from invertebrates to higher vertebrates(ref).”

A maddening thing that keeps showing up in my longevity studies is that everything seems somehow to be connected to just about everything else, and HSP70 seems to be no exception.  For example it seems to have a role in the mitochondria as discussed in the 2010 publication Understanding the functional interplay between mammalian mitochondrial Hsp70 chaperone machine components.  “Mitochondria biogenesis requires the import of several precursor proteins that are synthesized in the cytosol. The mitochondrial heat shock protein 70 (mtHsp70) machinery components are highly conserved among eukaryotes, including humans. However, the functional properties of human mtHsp70 machinery components have not been characterized among all eukaryotic families. To study the functional interactions, we have reconstituted the components of the mtHsp70 chaperone machine (Hsp70/J-protein/GrpE/Hep) and systematically analyzed in vitro conditions for biochemical functions. We observed that the sequence-specific interaction of human mtHsp70 toward mitochondrial client proteins differs significantly from its yeast counterpart Ssc1. Interestingly, the helical lid of human mtHsp70 was found dispensable to the binding of P5 peptide as compared with the other Hsp70s. We observed that the two human mitochondrial matrix J-protein splice variants differentially regulate the mtHsp70 chaperone cycle. Strikingly, our results demonstrated that human Hsp70 escort protein (Hep) possesses a unique ability to stimulate the ATPase activity of mtHsp70 as well as to prevent the aggregation of unfolded client proteins similar to J-proteins. We observed that Hep binds with the C terminus of mtHsp70 in a full-length context and this interaction is distinctly different from unfolded client-specific or J-protein binding. In addition, we found that the interaction of Hep at the C terminus of mtHsp70 is regulated by the helical lid region. However, the interaction of Hep at the ATPase domain of the human mtHsp70 is mutually exclusive with J-proteins, thus promoting a similar conformational change that leads to ATPase stimulation. Additionally, we highlight the biochemical defects of the mtHsp70 mutant (G489E) associated with a myelodysplastic syndrome.”  This study illustrates that although the HSP pathway is highly conserved across multiple species, evolutionary changes have occurred, for example in how the mitochondrial HSP70 works in yeast and humans. 

The research literature related to HSPs consists of at least hundreds of documents and those cited here provide only a small sample.  Some summary conclusions are:

:·       The hormetic actions of HSPs appear to be evolutionarily conserved and apply to thousands of species, yeasts and plants as well as animal. They actions have to do with reaction to and protection against stresses of various kinds on the cellular level.

·       The same or almost the same HSP genes exist across numerous species.  A great deal of knowledge of human HSP70 comes from study of oysters.

·       In some particular  cases, however, HSP genes in humans might not be quite the same or work differently.

·       HSP70 works through complicated biological mechanisms and one of its functions is to properly refold proteins in the endoplasmic reticulum that have been unfolded due to stress.

·       As pointed out in earlier blog entries, the hormetic responses of HSP70 in humans may be evoked by exercise, taking cur cumin or certain other supplements, or many other mild stressors.  The results are often health-giving and possibly exercise  longevity effects on the organism.

·       Knowledge of heat shock proteins and the mechanisms of hormesis is primitive, perhaps comparable to knowledge of the American Continent among Europeans in 1600. 

·       There is much to be learned and a lot of current research on these subjects.   Perhaps new surprises are in store about new ways to harness HSP responses for disease prevention and life extension.  We will see.

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28. June 2010 by admin.

The AMPK signaling pathway is one that is increasingly being viewed as playing a central role in metabolism and growth(ref). And that pathway appears to have a lot to do with longevity.  In fact, it is possible that some degree of life extension in humans might be realized through activation of AMPK. I review selected facts and publications about AMPK here and its relationship to other longevity topics previously discussed in this blog.  I discuss the possible role of AMPK activation as a diabetes treatment and how exercise activates AMPK.  Finally, I discuss the anti-aging effects of metformin, a widely-used diabetes drug that activates AMPK, and how exercise and several supplements in my dietary regimen also activate AMPK and may therefore have anti-aging effects.

About AMPK

AMP-activated protein kinase (AMPK) acts like a thermostat in the body’s metabolic handling of energy.  AMP stands for Adenosine 5-monophosphate.  AMPK “is viewed as a fuel sensor for glucose and lipid metabolism. — In mammals, the control of glucose homoeostasis is governed by the balance between glucose absorption from the intestine, endogenous production by the liver and uptake and metabolism by peripheral tissues. This requires continuous adaptation of metabolic pathways to maintain glycaemia in the physiological range. The AMP-activated protein kinase (AMPK) has been proposed to act as a ‘metabolic master switch’ capable of mediating the cellular adaptation to nutritional environmental variations. AMPK is a ubiquitous serine/threonine protein kinase activated in response to environmental or nutritional stress factors which deplete intracellular ATP levels, including heat shock, hypoxia, hypoglycaemia and prolonged exercise. Regardless, the result of AMPK activation is the inhibition of energy-consuming biosynthetic pathways, such as fatty acid and sterol synthesis, and activation of ATP-producing catabolic pathways, such as fatty acid oxidation(ref).”  One of the catalytic subunits of AMPK, AMPKα2, also appears to have additional functions: it controls whole-body insulin sensitivity and has a role in coordinating autonomous nervous system activity(ref).

The 2005 paper AMP-activated protein kinase: ancient energy gauge provides clues to modern understanding of metabolism offers another view.  “The AMP-activated protein kinase (AMPK) is an evolutionarily conserved sensor of cellular energy status, and recent data demonstrate that it also plays a critical role in systemic energy balance. AMPK integrates nutritional and hormonal signals in peripheral tissues and the hypothalamus. It mediates effects of adipokines (leptin, adiponectin, and possibly resistin) in regulating food intake, body weight, and glucose and lipid homeostasis. AMPK is regulated by upstream kinases of which the tumor suppressor, LKB1, is the first to be identified. Complex signaling networks suggest that AMPK may prevent insulin resistance, in part by inhibiting pathways that antagonize insulin signaling. Through signaling, metabolic, and gene expression effects, AMPK enhances insulin sensitivity and fosters a metabolic milieu that may reduce the risk for obesity and type 2 diabetes.”

The 2007 paper AMPK and SNF1: Snuffing Out Stress offers yet-another take.  “In mammals, metabolic stresses that inhibit ATP synthesis (e.g., hypoglycemia) or accelerate ATP consumption (e.g., muscle contraction) cause increases in the cellular AMP:ATP ratio that activate the AMP-activated protein kinase (AMPK) system. AMPK protects cells against such stresses by activating alternate catabolic pathways and inhibiting cell growth and division. This cellular energy-sensing role is most likely the function for which the AMPK system originally evolved. However, in multicellular organisms it also plays a key role in the regulation of whole-body energy balance, being involved in the control of food intake and energy expenditure by mediating effects of hormones like leptin and adiponectin (Kahn et al., 2005).”

The AMPK 1 catalytic subunit of AMPK plays a role in muscle health as described in the 2005 publication AMP-activated protein kinase signaling stimulates VEGF expression and angiogenesis in skeletal muscle.  “Here, we investigated whether AMPK signaling in muscle has a role in regulating VEGF-mediated angiogenic processes. — These data indicate that AMPK-p38 MAPK signaling cascade can increase VEGF production in muscle and promote angiogenesis in response to ischemic injury.”  Additional non-metabolic functions of AMPK are discussed in the 2007 publication The AMP-activated protein kinase: more than an energy sensor.

AMPK and Type 2 Diabetes

The 2009 publication AMPK: An Emerging Drug Target for Diabetes and the Metabolic Syndrome is one of many highlighting the possible use of the AMPK channel for the control of diabetes and metabolic syndrome. “According to National Diabetes Statistics, the number of people with diagnosed and undiagnosed diabetes in the United States reached 23.6 million, which is 7.8% of the general population, in 2007. The total number of people worldwide with diabetes is projected to rise to 366 million in 2030. A number of therapeutic agents exist for the treatment of type 2 diabetes mellitus (T2DM), including metformin, sulfonylureas, DPP-4 inhibitors, PPARγ agonists, α-glucosidase inhibitors, insulin, and GLP-1 analogs. However, in addition to inadequate efficacy and durability, some of these agents suffer from liabilities, including hypoglycemia, weight gain, edema, fractures, lactic acidosis, and gastrointestinal intolerance (Nathan et al, 2009).   In aggregate, there is a pressing need to develop novel modalities for the treatment of diabetes to stem the spread of this global epidemic. AMP-activated protein kinase (AMPK) is a potential target for novel agents that may meet this challenge.”  Metformin in particular is an already widely-used AMPK activator.

Agents that can increase expression of AMPK

A number of known substances have a capacity to directly or indirectly activate AMPK including metformin, thiazolidinediones, adiponectin, leptin, ciliary neurotrophic factor, interleukin-6, alpha-lipoic acid, resveratrol, epigallocatechin-3-gallate (a main catechin of green tea), cannabinoids, ghrelin(ref) and certain plant polyphenols(ref).  The therapeutic usefulness of these substances as AMPK activators except for metformin is mostly still to be explored.

AMPK and exercise

Even brief bouts of exercise activate AMPK.  The 2009 publication Brief intense interval exercise activates AMPK and p38 MAPK signaling and increases the expression of PGC-1alpha in human skeletal muscle reports “We tested the hypothesis that an acute session of intense intermittent cycle exercise would activate signaling cascades linked to mitochondrial biogenesis in human skeletal muscle — We conclude that signaling through AMPK and p38 MAPK to PGC-1alpha may explain in part the metabolic remodeling induced by low-volume intense interval exercise, including mitochondrial biogenesis and an increased capacity for glucose and fatty acid oxidation.”  Among other publications relating to the same theme is the 2009 report Molecular responses to high-intensity interval exercise.

AMPK and aging

AMPK activity is key for mitochondrial biogenesis and declines with age.  The 2010 publication Regulation of mitochondrial biogenesis points this out.  “Mitochondrial dysfunction is an important component of different diseases associated with aging, such as Type 2 diabetes and Alzheimer’s disease. PGC-1alpha (peroxisome-proliferator-activated receptor gamma co-activator-1alpha) is a co-transcriptional regulation factor that induces mitochondrial biogenesis by activating different transcription factors — The latter drives transcription and replication of mitochondrial DNA. PGC-1alpha itself is regulated by several different key factors involved in mitochondrial biogenesis, which will be reviewed in this chapter. Of those, AMPK (AMP-activated protein kinase) is of major importance. AMPK acts as an energy sensor of the cell and works as a key regulator of mitochondrial biogenesis. AMPK activity has been shown to decrease with age, which may contribute to decreased mitochondrial biogenesis and function with aging.

The 2008 publication Mitochondrial biogenesis and healthy aging identifies yet-another theory of aging: that aging is due to decline in biogenesis of cell mitochondria.  The publication discusses how not only AMPK but how also some other old friends like calorie restriction  and even resveratrol might be implicated. “Aging is associated with an overall loss of function at the level of the whole organism that has origins in cellular deterioration. Most cellular components, including mitochondria, require continuous recycling and regeneration throughout the lifespan. Mitochondria are particularly susceptive to damage over time as they are the major bioenergetic machinery and source of oxidative stress in cells. Effective control of mitochondrial biogenesis and turnover, therefore, becomes critical for the maintenance of energy production, the prevention of endogenous oxidative stress and the promotion of healthy aging. Multiple endogenous and exogenous factors regulate mitochondrial biogenesis through the peroxisome proliferator-activated receptor gamma coactivator-1alpha (PGC-1alpha). Activators of PGC-1alpha include nitric oxide, CREB and AMPK. Calorie restriction (CR) and resveratrol, a proposed CR mimetic, also increase mitochondrial biogenesis through activation of PGC-1alpha. Moderate exercise also mimics CR by inducing mitochondrial biogenesis. Negative regulators of PGC-1alpha such as RIP140 and 160MBP suppress mitochondrial biogenesis. Another mechanism involved in mitochondrial maintenance is mitochondrial fission/fusion and this process also involves an increasing number of regulatory proteins. Dysfunction of either biogenesis or fission/fusion of mitochondria is associated with diseases of the neuromuscular system and aging, and a greater understanding of the regulation of these processes should help us to ultimately control the aging process.”

Activation of the AMPK pathway results in inhibition of the mTOR pathway conferring possible longevity benefits(ref)(see this diagram).  It is known that inhibition of mTOR expression can result in life extension for flies, worms and mice.  See the blog entries More mTOR links to aging theories, Viva mTOR! Caveat mTOR!  and Longevity genes, mTOR and lifespan.

Anti-aging interventions

Metformin is a drug which is widely used for treating Type 2 diabetes.  Metformin is an AMPK activator(ref) and suppressor of mTOR and has been considered as a candidate health-extending and possibly life-extending substance.  Several publications have appeared relating metformin to aging such as studies that indicate that metformin slows down aging in certain strains of transgenic mice. “Here we show the chronic treatment of female outbred SHR mice with metformin (100 mg/kg in drinking water) slightly modified the food consumption but decreased the body weight after the age of 20 months, slowed down the age-related switch-off of estrous function, increased mean life span by 37.8%, mean life span of last 10% survivors by 20.8%, and maximum life span by 2.8 months (+10.3%) in comparison with control mice(ref).” “The chronic treatment of female transgenic HER-2/neu mice with metformin (100 mg/kg in drinking water) slightly decreased the food consumption but failed in reducing the body weight or temperature, slowed down the age-related rise in blood glucose and triglycerides level, as well as the age-related switch-off of estrous function, prolonged the mean life span by 8% (p < 0.05), the mean life span of last 10% survivors by 13.1%, and the maximum life span by 1 month in comparison with control mice. The demographic aging rate represented by the estimate of respective Gompertz’s parameter was decreased 2.26 times. The metformin-treatment significantly decreased the incidence and size of mammary adenocarcinomas in mice and increased the mean latency of the tumors(ref).”

The 2010 publication Metformin induces a dietary restriction-like state and the oxidative stress response to extend C. elegans Healthspan via AMPK, LKB1, and SKN-1 reviews the case for metformin as a life-extending substance.  The publication reports “Metformin, a biguanide drug commonly used to treat type-2 diabetes, has been noted to extend healthspan of nondiabetic mice, but this outcome, and the molecular mechanisms that underlie it, have received relatively little experimental attention. To develop a genetic model for study of biguanide effects on healthspan, we investigated metformin impact on aging Caenorhabditis elegans. We found that metformin increases nematode healthspan, slowing lipofuscin accumulation, extending median lifespan, and prolonging youthful locomotory ability in a dose-dependent manner. — Energy sensor AMPK and AMPK-activating kinase LKB1, which are activated in mammals by metformin treatment, are essential for health benefits in C. elegans, suggesting that metformin engages a metabolic loop conserved across phyla. — skn-1, which functions in nematode sensory neurons to promote DR longevity benefits and in intestines for oxidative stress resistance lifespan benefits, must be expressed in both neurons and intestines for metformin-promoted healthspan extension, supporting that metformin improves healthy middle-life aging by activating both DR and antioxidant defense longevity pathways. In addition to defining molecular players operative in metformin healthspan benefits, our data suggest that metformin may be a plausible pharmacological intervention to promote healthy human aging.”

Some blog writers have gone so far as to suggest that metformin could be used as an anti-aging drug although I stop short of advocating that here.  As more is learned about the AMPK pathway and its relationship to mTOR, and as more longevity experiments are done on animals using metformin, I might review that choice.  My suggested combined anti-aging firewalls Supplement Regimen already includes other probable activators of AMPK as mentioned above including alpha-lipoic acid, resveratrol, green tea supplements and a number of other plant polyphenols.  I also regularly exercise which activates AMPK.  I don’t know how good a job these do towards suppression of mTOR and life extension.  It could well be that many of the positive actions of those supplements result from activating AMPK.

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25. June 2010 by admin.

I have frequently asserted that telomere lengths do not decline in a uniform manner through life but depend on the interaction of multiple endogenous and extrinsic factors.  Two important factors are stress and exercise.  A new study in Plos One lends light on the relationship among these factors and telomere lengths:  The Power of Exercise: Buffering the Effect of Chronic Stress on Telomere Length.  This blog entry reviews interesting previous research relating to the impacts of stress and exercise on telomere lengths and describes the new findings.  For background, there is the Telomere Shortening and Damage theory of aging described in my treatise and a number of previous posts relating to telomere lengths which you can find by searching in this blog.

Stress

There are many forms of stress, social, physical and emotional, and these may be temporary, recurring or chronic.  Stress can result from external sources like injury or loss of a relative or result from internal conditions like a disease or mood disorder.    In the blog entries Stress and longevity and Hormesis and age retardation I discussed how some manageable forms of body stress can lead to a hormetic response, mobilization of heat shock proteins that actually confer health and longevity benefits, while more intense or more prolonged forms of stress may lead to multiple pathological conditions and premature aging.  For example, the stress of parachute jumping could possibly be good for you as suggested in the publication Emotional stress induced by parachute jumping enhances blood nerve growth factor levels and the distribution of nerve growth factor receptors in lymphocytes.  On the other hand, stress of prolonged unemployment could be bad for you even after you find a job, as suggested in the report History of unemployment predicts future elevations in C-reactive protein among male participants.  I also discussed how several dietary supplements like curcumin exercise positive effects in part through activating the body’s heat-shock stress response. 

There is a significant body of research literature associated with the negative effects of chronic or excess stress including immune system dysregulation, premature immunosenescence, elevated blood pressure and cortisol response, and undetected Type 2 diabetes(ref)(ref)(ref)(ref)(ref)(ref)(ref)(ref) which I will not review here.  Such stress is often viewed as associated with accelerated aging.

 Telomeres, telomerase and stress

The 2004 publication Accelerated telomere shortening in response to life stress was one of the first of many to link telomere shortening to stress. “We investigated the hypothesis that stress impacts health by modulating the rate of cellular aging. Here we provide evidence that psychological stress–both perceived stress and chronicity of stress–is significantly associated with higher oxidative stress, lower telomerase activity, and shorter telomere length, which are known determinants of cell senescence and longevity, in peripheral blood mononuclear cells from healthy premenopausal women. Women with the highest levels of perceived stress have telomeres shorter on average by the equivalent of at least one decade of additional aging compared to low stress women.” 

A 2006 study suggested that telomere shortening could be a mechanism through which stress leads to accelerated aging: Telomere shortening and mood disorders: preliminary support for a chronic stress model of accelerated aging.  “Little is known about the biological mechanisms underlying the excess medical morbidity and mortality associated with mood disorders. Substantial evidence supports abnormalities in stress-related biological systems in depression. Accelerated telomere shortening may reflect stress-related oxidative damage to cells and accelerated aging, and severe psychosocial stress has been linked to telomere shortening. We propose that chronic stress associated with mood disorders may contribute to excess vulnerability for diseases of aging such as cardiovascular disease and possibly some cancers through accelerated organismal aging. METHODS: Telomere length was measured by Southern Analysis in 44 individuals with chronic mood disorders and 44 nonpsychiatrically ill age-matched control subjects. RESULTS: Telomere length was significantly shorter in those with mood disorders, representing as much as 10 years of accelerated aging. — These results provide preliminary evidence that mood disorders are associated with accelerated aging and may suggest a novel mechanism for mood disorder-associated morbidity and mortality.”

The 2006 report Insulin resistance, oxidative stress, hypertension, and leukocyte telomere length in men from the Framingham Heart Study suggests another key link between telomere lengths, insulin resistance and hypertension.  ”Collectively, these observations suggest that hypertension, increased insulin resistance and oxidative stress are associated with shorter leukocyte telomere length and that shorter leukocyte telomere length in hypertensives is largely due to insulin resistance.”

A May 2010 publication Childhood adversities are associated with shorter telomere length at adult age both in individuals with an anxiety disorder and controls advances the hypothesis that stress leads to accelerated aging via telomere shortening.   “Accelerated leukocyte telomere shortening has been previously associated to self-perceived stress and psychiatric disorders, including schizophrenia and mood disorders. We set out to investigate whether telomere length is affected in patients with anxiety disorders in which stress is a known risk factor. We also studied the effects of childhood and recent psychological distress on telomere length. We utilized samples from the nationally representative population-based Health 2000 Survey that was carried out between 2000-2001 in Finland to assess major public health problems and their determinants. — Our results suggest that childhood stress might lead to accelerated telomere shortening seen at the adult age.”

Another slightly earlier 2010 study Childhood maltreatment and telomere shortening: preliminary support for an effect of early stress on cellular aging had the same theme, that childhood stress can lead to shorter telomeres and perhaps accelerated aging in adult life. “Based on previous evidence linking psychosocial stress to shorter telomere length, this study was designed to evaluate the effect of childhood adversity on telomere length. — These results extend previous reports linking shortened leukocyte telomere length and caregiver stress to more remote stressful experiences in childhood and suggest that childhood maltreatment could influence cellular aging.”

Telomere lengths stress and exercise

The first articles to show up relating telomerase and telomere lengths to exercise seemed to express surprise that exercise did not affect observed levels of telomerase, like the 2001 paper Telomerase activity is not altered by regular strenuous exercise in skeletal muscle or by sarcoma in liver of rats.  “We conclude that mild and strenuous exercise training does not significantly affect the activity of telomerase in the systems studied. Exercise training during sarcoma significantly retards the development of tumors and could possibly serve as a positive adjunct to treatment.”

A 2003 study looked at the result of exercise fatigue:  Athletes with exercise-associated fatigue have abnormally short muscle DNA telomeres. “In this study, we have compared a marker of skeletal muscle regeneration of athletes with exercise-associated chronic fatigue, a condition labeled the “fatigued athlete myopathic syndrome” (FAMS), with healthy asymptomatic age- and mileage-matched control endurance athletes. — The minimum value of TRF lengths (4.0 +/- 1.8 kb) measured on the DNA from vastus lateralis biopsies from these athletes were significantly shorter than those from 13 age- and mileage-matched control athletes (5.4 +/- 0.6 kb, P < 0.05). Three of the FAMS patients had extremely short telomeres (1.0 +/- 0.3 kb). The minimum TRF lengths of the remaining 10 symptomatic athletes (4.9 +/- 0.5 kb, P < 0.05) were also significantly shorter that those of the control athletes.”

The 2008 paper The effects of regular strength training on telomere length in human skeletal muscle reported “A recent study has reported abnormally short telomeres in skeletal muscle of athletes with exercise-associated fatigue. This important report raises the question of whether long-term practice of sports might have deleterious effects on muscle telomeres. Therefore, we aimed to compare telomere length of a group of power lifters (PL; N = 7) who trained for 8 +/- 3 yr against that of a group of healthy, active subjects (C; N = 7) with no history of strength training. — CONCLUSION: These results show for the first time that long-term training is not associated with an abnormal shortening of skeletal muscle telomere length. Although the minimum telomere length in PL remains within normal physiological ranges, a heavier load put on the muscles means a shorter minimum TRF length in skeletal muscle.”

A recent 2010 paper looks at the long-term consequences of strenuous exercise on telomere lengths: Skeletal muscle telomere length in healthy, experienced, endurance runners.  “Measuring the DNA telomere length of skeletal muscle in experienced endurance runners may contribute to our understanding of the effects of chronic exposure to endurance exercise on skeletal muscle. This study compared the minimum terminal restriction fragment (TRF) length in the vastus lateralis muscle of 18 experienced endurance runners (mean age: 42 +/- 7 years) to those of 19 sedentary individuals (mean age: 39 +/- 10 years). The runners had covered almost 50,000 km in training and racing over 15 years. Minimum TRF lengths measured in the muscle of both groups were similar (P = 0.805) and within the normal range. Minimum TRF length in the runners, however, was inversely related to their years spent running (r = -0.63, P = 0.007) and hours spent training (r = -0.52, P = 0.035). Therefore, since exposure to endurance running may influence minimum TRF length, and by implication, the proliferative potential of the satellite cells, chronic endurance running may be seen as a stressor to skeletal muscle.”

Telomere length, stress and exercise

Finally, a new twist is suggested in the publication:  The Power of Exercise: Buffering the Effect of Chronic Stress on Telomere Length.  “Chronic psychological stress is associated with detrimental effects on physical health, and may operate in part through accelerated cell aging, as indexed by shorter telomeres at the ends of chromosomes. However, not all people under stress have distinctly short telomeres, and we examined whether exercise can serve a stress-buffering function. We predicted that chronic stress would be related to short telomere length (TL) in sedentary individuals, whereas in those who exercise, stress would not have measurable effects on telomere shortening. — Participants were categorized into two groups-sedentary and active (those getting Centers for Disease Control-recommended daily amount of activity). The likelihood of having short versus long telomeres was calculated as a function of stress and exercise group, covarying age, BMI and education. Logistic regression analyses revealed a significant moderating effect of exercise. As predicted, among non-exercisers a one unit increase in the Perceived Stress Scale was related to a 15-fold increase in the odds of having short telomeres (p<.05), whereas in exercisers, perceived stress appears to be unrelated to TL (B = −.59, SE = .78, p = .45).”  This was a relatively small (63 healthy post-menopausal women aged between 54 and 82) and short (3 days) study using a self-evaluation 10-item questionnaire to measure psychological stress.  Nonetheless the implication is most interesting: exercise can nullify erosion in telomere lengths due to psychological stress.

I remind my readers of the January 2010 blog post Vitamins, supplements and telomerase - upregulation or downregulation? That post points to a study in which telomere lengthening was observed over a long period of time for a sizeable portion of the population studied. As stated in my treatise, “It appears that taking a number of popular supplements in the anti-aging firewalls supplement regimen like Vitamin E, fish oils, Vitamin D3 and resveratrol can lead to telomeres being longer than they otherwise might be, possibly because they induce the production of telomerase, possibly for other reasons. And, several of these supplements actually turn off telomerase in cancer cells.”

To sum it up

o   Childhood stress resulting in shorter telomeres may result in accelerated cellular aging later in life.

o   There is a “sweet spot” range for exercise stress within which the impact of the exercise is positive and health-producing and there is no stress-related telomere erosion, even if the exercise is repeated over the long term.  The sweet spot range may depend on the state of the individual.

o   If exercise is pursued too vigorously, to the point where it produces chronic fatigue, or pursued consistently as an endurance activity, telomere erosion may ensue, at least in muscles.

o   Psychological stress can produce telomere erosion even within a few days, but “sweet spot” exercising can prevent such erosion.

Final comments: 

-         There is much complication involved with telomere shortening or lengthening involving diet, health and age as well as stress and exercise.  The interplay of these and multiple internal factors is not well understood. Most likely there are epigenetic regulators of telomere length and every day, perhaps every hour or minute, complicated programs throughout the body readjust telomere lengths, perhaps making them shorter, leaving them the same or even making them longer.

-      How telomerase activators like cycloastragenol play into the situation of lengthening telomeres is also not well understood.  See my April 2010 post Telomerase activators - what do they really do?

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23. June 2010 by admin.

Ever hear of humanin?  At the Paul K Glenn Symposium on Aging yesterday at Harvard, Dr. Pinchas Cohen gave a talk on The New World of Mitochondrial Proteins featuring humanin and other closely related proteins.  The subject is important because it points to a new and important function of mitochondria – generating protective proteins.  This blog post draws on material from that talk heavily augmented with materials from a number of published sources. 

Humanin is a mitochondria-derived peptide.  That is, humanin is expressed by mitochondrial genes in the 16s ribosomal RNA coding region.  The evidence suggests that gene transcription takes place in the mitochondria but translation into protein form takes place in the cytoplasm.  Humanin was independently cloned by three different groups in 2001.  It is one of some seven health-related peptides encoded by mitochondrial genes.

Several things have been learned about humanin:

·        Humanin is created by an evolutionary-conserved gene sequence and homolog versions of this sequence can be found in humans, mice, horses, nematodes, zebrafish and no doubt in many other species.

·        Humanin suppresses apoptosis by interfering with Bax activation (ref).  “HN prevents the translocation of Bax from cytosol to mitochondria. Conversely, reducing HN expression by small interfering RNAs sensitizes cells to Bax and increases Bax translocation to membranes. HN peptides also block Bax association with isolated mitochondria, and suppress cytochrome c release in vitro. Notably, the mitochondrial genome contains an identical open reading frame, and the mitochondrial version of HN can also bind and suppress Bax. We speculate therefore that HN arose from mitochondria and transferred to the nuclear genome, providing a mechanism for protecting these organelles from Bax(ref).” “The anti-apoptotic potential of HN appears to be dependent upon the formation of homodimers, as interfering with this process completely blocks its ability to suppress cell death [10]. Once dimerized, HN directly interacts with a variety of pro-apoptotic proteins, including Bax-related proteins [2] and insulin-like growth factor binding protein-3 (IGFBP-3) [11](ref).”

·        Humanin also works through ERK1/2 to mobilize calcium and provide an anti-inflammatory effect(ref)(ref). 

·        Tyrosine kinases and STAT3 in are involved in humanin-mediated neuroprotection(ref), particularly in the brain.

·        Humanin suppresses hepaptic glucose production, its main site of action being the hypothalamus(ref).

·        Humanin also works through STAT3 to exercise metabolic effects(ref).

·        Expression of humanin declines with age.  “Based upon the link of HN with two age-related diseases (AD and diabetes), we examined if there were age associated changes in HN levels. Indeed, the amount of detectable HN in hypothalamus, skeletal muscle, and cortex was decreased with age in rodents, and circulating levels of HN were decreased with age in humans and mice. — We conclude that the decline in HN with age could play a role in the pathogenesis of age-related diseases including AD and T2DM(ref).”

·        Humanin appears in multiple tissue types “Endogenous HN is both an intracellular and secreted protein and has been detected in normal mouse testis and colon at specific stages of development [3]. In addition to brain, colon and testis, we have shown the presence of HN by western blot in rodent heart, ovary, pancreas and kidney (unpublished data). In addition, our group has demonstrated the presence of HN in cerebral spinal fluid (CSF), seminal fluid and plasma, with levels in the biologically active range (Cohen & Hwang, unpublished data)(ref).”

·        Finally, the mitochondrial genes that make humanin may also transmigrate out of mitochondria into cell nucleuses and be incorporated into chromosomal DNA.   So, some of the humanin observed in tissues may result from ordinary protein-generating mechanisms.

Humanin, neural protection and Alzheimer’s disease

·        Humanin was from the start recognized to be a powerful neuroprotective substance.  Humanin blocks the process through which beta-amyloid causes neuronal death and was thought to be possibly useful for prevention or treatment of Alzheimer’s disease.  As outlined in one of the initial 2001 papers Mechanisms of Neuroprotection by a Novel Rescue Factor Humanin from Swedish Mutant Amyloid Precursor Protein: “We report a novel gene, designated Humanin (HN) cDNA, that suppresses neuronal cell death by K595N/M596L-APP (NL-APP), a mutant causing familial Alzheimer’s disease (FAD), termed Swedish mutant. — Therefore, HN suppressed neuronal cell death by NL-APP not through inhibition of Aβ42 secretion, but with two targets for its inhibitory action: (i) the intracellular toxic mechanism directly triggered by NL-APP and (ii) neurotoxicity by Aβ. HN will contribute to the development of curative therapy of AD, especially as a novel reagent that could mechanistically supplement Aβ-production inhibitors.” 

·        Humanin rescues cortical neurons treated with beta-amaloid in a concentration-dependent manner(ref).

·        The 2001 publication Detailed characterization of neuroprotection by a rescue factor humanin against various Alzheimer’s disease-relevant insults stated “A novel factor, termed Humanin (HN), antagonizes against neurotoxicity by various types of familial Alzheimer’s disease (AD) genes [V642I and K595N/M596L (NL) mutants of amyloid precursor protein (APP), M146L-presenilin (PS) 1, and N141I-PS2] and by Abeta1-43 with clear action specificity ineffective on neurotoxicity by polyglutamine repeat Q79 or superoxide dismutase 1 mutants. Here we report that HN can also inhibit neurotoxicity by other AD-relevant insults: other familial AD genes (A617G-APP, L648P-APP, A246E-PS1, L286V-PS1, C410Y-PS1, and H163R-PS1), APP stimulation by anti-APP antibody, and other Abeta peptides (Abeta1-42 and Abeta25-35).”  However, it was not clear how it worked to do that.

·        The 2008 publication A rescue factor for Alzheimer’s diseases: discovery, activity, structure, and mechanism states the practical case for humanin in AD.  “While understanding the mechanism of AD and the involvement of key players should lead to rational drug discovery against this disease, a traditional screening approach should also work for identifying drugs using AD models. We have used a cellular AD model, in which a cell death was induced by AD-causing neurotoxicities, and then screened the genes, which rescued the cells from the cell death. This resulted in isolation of a gene encoding a novel 24-amino acid long peptide, termed Humanin (HN), which protected neuronal cells at approximately microM level. Surprisingly, these gene products and the synthetic peptides not only protected neurons from cell death induced by Abeta-related neurotoxicities, but also Abeta-unrelated neurotoxicities. While a broad range of activities of HN against AD-related insults is discovered, the detailed mechanism of its action is still obscure.”  In other words, “we don’t know how it works, but it works.”

·        A 2009 publication suggests a mechanism of action: Humanin inhibits neuronal cell death by interacting with a cytokine receptor complex or complexes involving CNTF receptor alpha/WSX-1/gp130.  “Together, these results indicate that HN protects neurons by binding to a complex or complexes involving CNTFR/WSX-1/gp130.”

·        Humanin and protect against prion-induced and other forms of drug-induced neuron apoptosis(ref)(ref) and can also inhibit death in other types of cells.

Humanin and diabetes

Humanin appears to have several salutary effects with respect to diabetes

·        Humanin is an insulin secretalog.  Humanin is A Novel Central Regulator of Peripheral Insulin Action.  “Decline in insulin action is a metabolic feature of aging and is involved in the development of age-related diseases including Type 2 Diabetes Mellitus (T2DM) and Alzheimer’s disease (AD). A novel mitochondria-associated peptide, Humanin (HN), has a neuroprotective role against AD-related neurotoxicity. Considering the association between insulin resistance and AD, we investigated if HN influences insulin sensitivity. — Using state of the art clamp technology, we examined the role of central and peripheral HN on insulin action. — HN represents a novel link between T2DM and neurodegeneration and along with its analogues offers a potential therapeutic tool to improve insulin action and treat T2DM.”

·        HNG-F6a, an analog of humanin, has a powerful capability to suppress blood sugar in Zucker rats(ref). 

·        In non-obese diabetic mice, humanin both prevents and treats Type 1 Diabetes.  According to the 2009 paper The neurosurvival factor Humanin inhibits β-cell apoptosis via signal transducer and activator of transcription 3 activation and delays and ameliorates diabetes in nonobese diabetic mice “Humanin normalized glucose tolerance in NOD mice treated for 6 weeks, and their pancreata revealed decreased lymphocyte infiltration and severity. In addition, Humanin delayed/prevented the onset of diabetes in NOD mice treated for 20 weeks. In summary, Humanin treatment decreases cytokine-induced apoptosis in β-cells in vitro and improved glucose tolerance and onset of diabetes in NOD mice in vivo. This indicates that Humanin may be useful for islet protection and survival in a spectrum of diabetes-related therapeutics.”

Humanin and vascular processes

·         The 2010 publication Humanin is Expressed in Human Vascular Walls and Has a Cytoprotective Effect against Oxidized LDL-Induced Oxidative Stress suggests other roles for humanin in vascular and possibly cardiovascular health and disease processes.  “The current study demonstrates for the first time the expression of Humanin in the endothelial cell layer of human blood vessels. Exogenous addition of Humanin to endothelial cell cultures was shown to be effective against Ox-LDL-induced apoptosis. These findings suggest that Humanin may play a role and may have protective effect in early atherosclerosis in humans.” 

Other SHLPs – SHLP6

There are six additional small humanin-like mitochondria-derived peptides (SHLPs) that Dr. Cohen talked about.  Four of these are somewhat similar in their effects to Humanin but one, SHLP6 is very different and interesting in its effects.  SHLP1 through SHLP5 line humanin are anti-apoptosis pro cell-survival substances, although they have varied neuro-protective and other effects.   I will not discuss those here.  SHLP6, however, is strongly pro-apoptosis, inhibits cancer cell growth in-vitro, inhibits VEGF, inhibits tumor growth and angiogenesis in vivo.  Its levels are reduced in prostate cancer – pretty much the opposite profile of humanin and the first five SHLPs.  One important difference is that levels of humanin and the first 5 SHLPs in the brain are reduced to half or less in the process of aging, but the level of SHLP6 may actually increase.  In blood plasma, the level of humanin drops to less than half with age but the level of SHLP6 remains nearly the same.   SHLP6 is also a highly conserved 20 amino-acid peptide.  It could be that, evolutionary-speaking, there is an anti-cancer survival advantage to high levels of SHLP6 with age.  It is effective in inducing apoptosis in prostate, breast and other cancer cell lines.  Potentially, SHLP6 could provide a basis for new cancer prevention or treatment approaches. To sum it up, mitochondria-derived peptides, humanin and its cousins, appear to define a new and largely unexploited field in biology with particular implications related to two important diseases of the elderly - Alzheimer’s disease and diabetes.  Humanin and some of its cousins seem to have similar health and longevity effects as SIRT1 and certain heat-shock proteins involved in hormesis responses(ref)(ref).  As time goes on I plan to explore possible relationships between these pro-life proteins and report on them in this blog.Somebody reading this blog is bound to ask me “Where can I get humanin or humanin-promoting dietary substances or supplements?”  I don’t know, except to suggest that keeping mitochondria healthy is probably the best way to keep humanin levels up with aging.  So, please see the Mitochondrial Damage Firewall in my treatise.

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