Research - 2002
Myocardial Insulin Resistance: Mechanisms of TNFa and Insulin Antagonism in the Cardiac Muscle Cell
Huda E. Shubeita, Ph.D.
Rees-Stealy Research Foundation
San Diego, CA
A major complication of NIDDM is cardiac disease. Patients afflicted with NIDDM experience depression of cardiac function (diabetic cardiomyopathy) due to alterations in the contractile properties of the cardiac muscle. This researcher has recently demonstrated that insulin maintains the normal contractility of cardiac muscle cells. Tumor necrosis factor (TNFa), a hormone produced by the immune system is recognized for its pro-inflammatory responsiveness to injury and its anti-viral, anti-tumor effects. However, it has been demonstrated that diseases of cardiac muscle are associated with elevated TNFa blood levels. This research group has demonstrated that TNFa triggers negative inotropy and apoptosis in cardiac muscle cells. Recent findings have emerged indicating that TNFa may be a very important molecule produced by fat cells during obesity and interferes with insulin action. However, the role of TNFa in the cardiac effects of diabetes has not been explored. The aim of this investigation is to determine whether TNFa directly interferes with the cardiotropic actions of insulin and to assess the mechanisms of this action. Results of this research should provide information for developing diagnostic tools aimed at determining whether subjects afflicted with TNFa-related disorders, such as septic shock, would be predicted to be susceptible to myocardial insulin resistance. By gaining a thorough understanding of the factors involved, it may be possible to develop a new therapeutic intervention in the treatment of cardiac failure.
Educational Attack on Juvenile Diabetic Blindness with Pictures
James O'Rourke, M.D.
Professor of Pathology and Surgery
University of Connecticut Health Center
Diabetic blindness is not a disease of the retina or an eye disease, but it is a disease of the blood vessels in the retina. Diabetes causes blindness by damaging the small blood vessels that nourish the retina. Viewing the retina is one of the most effective means of detecting early blood vessel damage in diabetes. Unfortunately, viewing the retinal blood vessels through an undilated pupil provides only a limited, transient image. New retinal digital imaging technology now makes it possible to instantly image a retina and transmit copies of the picture to physicians' offices electronically and store them on discs for future reference. Additionally, because patients can actually see the damage diabetes is doing to their retinas, they are better motivated to comply with follow up treatment. Also, by seeing retinal blood vessel damage early on, doctors are able to monitor and adjust blood sugar levels. Early detection and prompt treatment of retinal diabetes requires more efficient interaction among specialists in order to reverse the diabetic blindness problem. National research trials have shown that properly timed laser treatments can prevent more than half of the blindness seen in Type I diabetes. Dr. O'Rourke's project will provide a one time free retinal image to every Type I diabetic who volunteers for a community sponsored screening drive in Connecticut. The five year goal of this project is to install this new imaging technology in most community hospitals and establish new ties between community groups and university teaching centers.
The Treatment of Type I Diabetes Mellitus With Cytokine Administration
Douglas O. Sobel, M.D.
Georgetown University Medical Center
Since Type I diabetes is caused by the immune system, there have been many attempts to immunologically treat patients with Type I diabetes. However, all attempts have been unsuccessful. Cytokines -- substances made in our own immune system -- have successfully treated some human diseases and potentially may be helpful in Type I diabetes. Dr. Sobel has demonstrated that inducers of cytokines inhibit the development of diabetes in the BB rat. He now plans to explore the effect of individual cytokines on the development of diabetes in the diabetes prone BB rat in order to determine: 1) the effective dose and optimal time of administration for long lasting protection, 2) the shortest duration of cytokine treatment required to give maximal protection, 3) if cytokine induces a generalized state of depressed cellular immunity, and 4) if cytokine treatment prevents diabetes by altering immune cells, called immunoregulatory cells.
Diabetes Home Care Education Project
Bethany Hall-Long, Ph.D., RNC
Assistant Professor, College of Health & Nursing Sciences
University of Delaware
The purpose of this pilot study is to evaluate effectiveness of a home health education intervention on the knowledge and health behavior/status of adults with diabetes as measured by client outcomes using evaluation data. Assigned nurses, certified diabetes nurse educators, and undergraduate student nurses will use the same educational guidelines to teach and monitor the sample across the 6-8 month timeframe. While they are teaching, they will collect client/family information on the following areas: history (physical and psychological), diet, exercise, self blood glucose monitoring, foot care, medication, and medical follow-up. The focus will be on the individual and family to enhance lifestyle functioning for health promotion, especially in the areas of nutrition and exercise. Community resources such as exercise facilities, volunteer associations, grocery and health/nutrition stores, etc. will be utilized as needed. Diabetic, nursing, and exercise science faculty and students will collaborate with the VNA nurses, social workers, physical therapists, and other health care providers as needed. Findings and implications for the study will be used to improve upon diabetes education in the home and expand community outreach across the surrounding Mid-Atlantic Region using a campus-community partnership framework. A goal of this study is to develop a model home health education and community-campus outreach program to replicate across the country.
The Role of the Qa-1 Molecule in T-Cell Vaccination for Prevention of Type-1 Diabetes
Vassiliki Panoutsakopoulou, Ph.D.
Dana-Farber Cancer Institute
Type 1 diabetes is a disease caused by cells of the immune system (T-cells) that attack and destroy cells in the pancreas. Studies in this proposal are aimed at development of a self-defense mechanism that will inhibit the generation and activation of the self-destructive T-cells that cause diabetes. The approach proposed is called T-cell vaccination. In order to successfully elicit the required protective response, the self-destructive T-cells are treated and used in an attenuated form as a vaccine. This vaccine trains cells of the immune system to recognize and destroy the diabetes-causing cells, thus developing protection from the disease they normally cause. The proposed experiments will be performed using a well-established mouse model of diabetes, the NOD system, which is very similar to human diabetes and has been an effective tool in major research efforts in the past. In addition, the researchers will use methods that they successfully employed in the development of a protective response in a similar autoimmune disease (Herpes Stromal Keratitis). Knowledge acquired from these studies using the NOD mouse model will be important for development of successful T-cell vaccines for diabetes patients. Currently, there are no curative treatments for autoimmune disease and the possibility of using the body's own defense-system, rather than traditional invasive or painful procedures, is an intriguing possibility with enormous potential benefit to those, particularly children, that are afflicted with Type 1 diabetes.
Nutritional Approaches to Improve B Cell Function
Howard A. Wolpert, M.D.
Joslin Diabetes Center
The past decade has witnessed impressive progress in the identification of molecular genetic defects that confer susceptibility to diabetes. But this knowledge has not yet been translated into new therapeutic approaches to the management of diabetes. Although often overlooked in clinical practice, mitochondrial mutations which result in decreased insulin secretion by the pancreatic B Cell are a major cause of diabetes worldwide. Remarkably, in patients with mitochondrial mutations that result in muscular weakness, clinical symptoms and mitochondrial function can be improved by nutritional supplements that enhance mitochondrial metabolism. With the use of dietary supplements such as CoQ10, Creatine, and Carnitene, Dr. Wolpert demonstrated a significant improvement in glucose-stimulated insulin secretion in a patient with mitochondrial diabetes. In this study, he plans to extend these findings by establishing a screening program to identify individuals who are carriers of the mitochondrial mutations that cause diabetes. Carriers of the mutant gene will then be candidates for a therapeutic trial to examine whether these supplements can improve pancreatic B cell function and prevent progression to insulin-dependence. The successful application of this strategy will represent an important step in the development of nutritional approaches to the prevention and treatment of diabetes.
Topical Insulin Administration for the Treatment of Diabetic Retinopathy
Steven B. Koevary, Ph.D.
New England College of Optometry
Ocular Research Center
Diabetes mellitus is the leading cause of new cases of blindness in adults between the ages of 20 and 70. The goal of this project is to develop an approach for the prevention and possible reversal of diabetic retinopathy in an animal model of human diabetes. Using a unique approach that has not been reported previously, this research involves the topical application of insulin to the eye in the form of insulin eye drops which may prevent and possibly reverse diabetic retinopathy by restoring the insulin concentrations in the insulin-deficient retina in diabetics to normal. Direct application to the eye would obviate the need to achieve perfect systemic glucose control in order to prevent retinopathy. Insulin was shown to reverse the harmful effects of hyperglycemia in the retina through its action on such compounds as nitric oxide, the enzyme phospholipase C-B, and platelet activating factor. These factors, or in some cases their suppression in diabetes, impede retinal blood flow and cause retinal ischemia and are otherwise responsible for inducing retinopathy. Insulin reverses these effects. Insulin was also shown to have a direct vasodilatory effect on isolated retinal arterioles, thus promoting blood flow through the retina. If this direct replacement of deficient retinal insulin can prove to reverse the negative changes associated with retinopathy, this would have tremendous application as a way to prevent blindness in people with diabetes.
Total and Combinatorial Synthesis of Orally Active Insulin Mimetics
Michael C. Pirrung, Ph.D.
Professor of Chemistry
A naturally occurring chemical compound has recently been discovered from a fungus in the Congo. This new compound, demethylasterriquinone B1 (DAQB1), is effective (in mice) when given orally. Currently the compound must be isolated and purified from a fermentation broth in a multi-step procedure. Further development of this compound will require a virtually unlimited supply of it, which is unlikely to be provided by the original fermentation method. Because DAQB1 is a relatively simple natural product, it is reasonable that it could be prepared on a large scale by total chemical synthesis, which is the first goal of this research project. But it is unlikely to expect a molecule discovered in nature to have optimal activity as a human pharmaceutical without changing the chemical structure. A recent advance in drug development has arisen from a novel concept, combinatorial chemistry. In order to achieve the preparation of a combinatorial library, a general synthetic route must be developed that allows the use of "building blocks" of different chemical structure that are built onto a central core molecule. In fact, DAQ is such a molecule. The total chemical synthesis that is planned is readily adaptable to the combinatorial synthesis format, enabling libraries of hundreds or thousands of candidate insulin mimetic drugs to be prepared. These will then be tested in cell-based assays to identify the novel compounds that can be taken for further development in animals, and hopefully, ultimately, in humans.
The Role of High Density Insulin Receptor Positive T Cells in Type 1 Diabetes
Marcia F. McInerney, Ph.D.
University of Toledo
This researcher has evidence that T-cells with a high density of insulin receptors may be very important in causing diabetes in non-obese diabetic (NOD) mice, and is pursuing studies to characterize these cells and further access their importance. Although it has been well documented that activated T-cells bear insulin receptors, it has not been proven that these cells are unique and migrate to the pancreatic islets because of the insulin receptors. This research project seeks to further characterize certain insulin receptor T-cells (IRhi) and determine if insulin receptor expression on the surface of lymphocytes is important for diabetogenicity. If the IRhi T cells prove to be pathogenic, then down regulation of these receptors may prevent movement toward the islet and thus beta cell destruction. These experiments will generate novel information on diabetogenic T cells, and the characterization of these IRhi T cells could lead to development of more effective methods to block these damaging T lymphocytes from invading the islet. This would prevent beta cell destruction and the development of diabetes.
Structure determination of the human Protein Tyrosine Phosphatase-1B (hPTP-1B) gene; a negative regulator of insulin action.
George Argyropoulos, Ph.D.
Medical University of South Carolina
The development of Type 2 diabetes (and obesity) appears to require the interaction of dietary habits and a hereditary (genetic) predisposition. Evidence indicates that Type 2 diabetes follows a familial pattern: i.e. it is transmitted form generation to generation. This study aims to identify genetic factors that influence the development of obesity and Type 2 diabetes. To accomplish this goal, different genes that appear to be involved in the course of developing these diseases are being studied. One such gene is the protein tyrosine phosphatase 1B (PTP-1B) gene that has been shown to be a negative regulator of insulin action. Thus, people who do not make this protein at all or have low amounts of this protein may be protected against weight gain even when following a high fat diet. Complete lack or low presence of the PTP-1B protein could be the result of mutations in the gene or in the promoter (the driving mechanism) of the gene. This study will examine the PTP-1B gene for the presence of such mutations, but first the structure (i.e. the DNA make up) of the gene will need to be determined. Similarly, the promoter region of this gene will need to be identified. In this project, the goal is to determine the gene structure of PTP-1B and to identify its promoter. Then, the gene and its promoter will be screened for the presence of mutations that might predispose individuals to develop obesity and/or Type 2 diabetes.
Investigation of the Medicinal Effects of Garlic on Type 2 Diabetes Mellitus
Roger J. Zoorob, MD,MPH
Vice Chair and Residency Program Director
LSU School of Medicine
New Orleans, LA
Over the past several decades, research studies have demonstrated the positive effects of garlic on the treatment of blood pressure and high cholesterol in humans, as well as on the blood sugar of diabetic animals. However, the effect of garlic on diabetic humans has not been studied. This project will study the effect of garlic on blood sugar, blood pressure, and cholesterol in patients with type 2 diabetes. Healthy, non-pregnant patients over 18 diagnosed with type 2 diabetes will be randomized, via computer, to receive garlic or placebo. Baselines for fasting blood sugar, lipid profile, and hemoglobin A1c will be established and checked monthly while patients take 300 mg of dried garlic twice daily for three months. Participant data will be statistically examined. Individuals who took garlic will be compared with individuals who took placebo: health status (ie, blood sugar control, cholesterol, and blood pressure) after three months will be compared to status prior to entering the study. If participants who took garlic supplements can show de-creased blood pressure, cholesterol, and blood sugar, this could then become a cost effective alternative therapy for patients with diabetes. Furthermore, if garlic can help patients control their blood sugar, fewer prescription medications may be required, thereby reducing the danger of side effects.
Regulation of Leptin Receptor Signaling by Serine/Threonine Phosphorylation
Martin G. Myers, Jr. M.D.,Ph.D.
Joslin Diabetes Center/Harvard Medical School
The increasing incidence of type 2 diabetes in the U.S. largely reflects increases in obesity. The mechanisms that link obesity to insulin resistance and islet failure in type 2 diabetes and to other disease processes are only now beginning to be understood. Leptin is a recently described hormone that acts via the leptin receptor to control eating and energy (e.g.fat) storage: it also influences insulin secretion and sensitivity. Mutation of leptin or the leptin receptor results in obesity and diabetes. Leptin resistance, the impairment of the biochemical signals activated by the leptin receptor, appears to be involved in the genesis of obesity and type 2 diabetes in humans. One well established mechanism for resistance to hormones (including insulin resistance in type 2 diabetes) is the modification of hormone receptors by the process of Ser/Thr phosphorylation. The potentially important question of Ser/Thr phosphorylation-dependent inhibition of leptin receptor action remains largely unexplored. We have demonstrated at least one potentially important Ser/Thr phosphorylation event on the leptin receptor. The focus of this grant is to identify other potentially important Ser/Thr phosphorylation events on the leptin receptor and to understand how these events impact leptin action, which can lead to the identification of therapeutic targets to combat obesity and diabetes.
Mixed Bone marrow Chimerism as a Treatment for Autoimmune Diabetes
Igor Leykin, MD,Ph.D
Harvard School of Public Health
Dana Farber Cancer Institute
Insulin-dependent diabetes mellitus, (Type1 diabetes), is a chronic autoimmune disease resulting in complete destruction of insulin- producing B cells in pancreatic islets. Bone marrow transplantation (BMT) from disease-resistant donor into conditioned recipient non- obese diabetic (NOD) mice prevents the development of diabetes, pro-vided the transplantation is performed before extensive damage to the B cells has occurred. In addition, EMT has an advantage in the treatment of diabetes. Engraftment of non-identical (allogeneic or xenogeneic) pluripotent hematopoietic stem cells in recipient results in mutual tolerance among both host and donor lymphocytes, allowing not only modulation of autoimmune disease, but also tolerance toward donor-derived tissue, including pancreatic islets. Dr. Leykin's lab recently described a method of inducing tolerance that uses allO-BMT and costimulatory blockage, leading to high levels of allogeneic stem cell eng-raftment and permanent tolerance. Treatment of mice with a single injection of costimulatory blocers, a low dose of whole body irradiation, plus allogeneic BMT, reliably induces of high levels of stable donor hematopoiesis, what leads to T cell tolerance and high levels of chimerism. If the use of this conditioning regimen in NQD mice can pratect against insulitis and provide permanent tolerance toward transplantation of donor pancreatic tissue without the need for immunosuppressive therapy, this could offer a real breakthrough in providing a cure for Type 1 diabetes.
Phase II-III Study of Wound Healing in Diabetes Mellitus Ulceration
Arthur Dale Ericsson, MD
Director, Institute of Biologic Research
Between 600,000 to 800,000 people in the U.S. currently suffer from diabetic foot ulcers. The burden of these foot ulcers to individuals and society demonstrates the need for new and better products to treat these devastating wounds. A new biologic product, CuNeXuS™, when applied topically to surgical wounds in a small pilot study, had pro-vided a dramatic increased rate of wound healing, while at the same time significantly reducing inflammation and subsequent scar formation with little, if any, untoward reaction to the biological compound. Fol-lowing this wound healing study a pilot study was performed with dia-betic patients. These patients had severe ulceration with osteomyelitis and were on intravenous antibiotics. Using CuNeXuS™ as the primary wound care, each lesion was healed in 6 weeks. The largest measured 5 inches long,3/4 inches wide and was 3/4 inches deep at the onset of therapy. This study will test this biologic product in a larger sample of patients with diabetic ulcers. It is hoped that this research pro-ject can demonstrate the efficacy of this new form of wound healing that could dramatically alter the outlook and cost of treatment for so many people with diabetic ulcers.
Intensive Dietary Intervention in Non-lnsulin Dependent Diabetes Mellitus
Neal D. Barnard, M.D.and Mark Sklar, M.D.
Physicians Committee for Responsible Medicine
Evidence suggests that the dietary recommendations that are most effective in diabetes management may be similar to the low-fat vegetarian diets that have demonstrated to reverse coronary artery blockages. (Ornish l990, Esselstyn 1999). However, no study to date has examined the effect of a low-fat, vegetarian diet as an inter-vention for diabetes in a substantial number of participants, and most studies using plant-based (near vegetarian) diets have also included exercise as a major intervention component, making it hard to separate the effects of physical activity from those of diet or to ; reach any definitive conclusion as to which type of dietary interven-tion is best. A prior pilot trial conducted by PCRM in association with Georgetown University Dept. of Endocrinology showed that a 12 week intervention diet using a low-fat, vegetarian diet, controlled for exer-cise, permitted most participants to reduce their use of oral hypo-glycemic agents or insulin. The goal of this full trial study, which will be controlled for exercise, is to test the hypothesis that the same aggressive intervention diet can yield significant improvements of all key indices of diabetic control, including fasting serum glucose, insulin, and lipid concentrations, body weight, microalbuminuria, and medication requirements, compared to a control diet over a 12 week period.
Investigate a gene therapy strategy to improve the success of islet (or B-cell) transplantation
Illani Atwater, Ph.D.
Sansum Medical Research Institute
Santa Barbara, CA
Current Research to prevent and correct Type 1 diabetes has focused on development of strategies to protect insulin secreting cells from recognition and/or destruction by the immune system. Research on an enzyme known as IDO, (indoleamine 2,3-dioxygenase), showed that this enzyme was responsible for successful pregnancy by keeping levels of the amino acid tryptophan low in the placenta. And when IDO was inhibited in mice, the resulting inflammatory response directed against the embryos caused early abortion. Moreover, in vitro, the activation and proliferation of lymphocytes is profoundly depressed when the culture medium levels of tryptophan are low. These findings have led Dr. Atwater to propose a gene therapy strategy to improve the success of islet (or B-cell) transplantation. This is to incorporate the gene for IDO into islets or beta cells, which, upon transplantation, would then deplete their surroundings of tryptophan, which would inhibit approaching lymphocytes, and thus escape immune attack. The development of IDO expressing B-cells will then solve the 2 major problems facing transplantation as a cure for diabetes, namely, the long-term requirement for immune suppression therapy and the lack of sufficient viable islets.
Moreover, it is important to study how tryptophan affects lymphocytes. This project will attempt to define the role of tryptophan during lymphocyte activa-tion. This will help to engineer B-cells able to protect themselves against immune attack. Furthermore, this study will measure differences in the early immune response and in the tryptophan dependency of the response during the normal rejection process in contrast to the specific B-cell rejection response, which occurs in type 1 diabetes. It is important to understand the cellular mechanisms of these two processes in order to develop a strategy to cure by protecting B-cells from immune destruction after transplantation as well as to preventing diabetes by stopping the autoimmune destruction in Type 1 diabetes.
B Vitamin Supplementation in Diabetic Patients with Hyperhomocysteinemia
Joshua W. Miller, Ph.D.
Asst. Professor, Univ. of California, Davis,School of Medicine
Patients with diabetes suffer from higher rates of cardiovascular disease than the general population. The factors that contribute to these higher rates are not completely understood. An elevated level of an amino acid called 'homocysteine' in the blood is now recognized to be a risk factor for cardiovascular disease. We and others have found that many diabetics have elevated blood levels of homocysteine. This may contribute to the high rate of cardio-vascular disease in these patients. In this study, we will investi-gate whether or not lowering blood homocysteine levels in diabetic patients is beneficial. This project will determine if B Vitamin supplements can significantly lower blood homocysteine levels in diabetic patients, and Dr. Miller's lab will determine if lowering blood homocysteine concentrations will reduce inflammation associated with cardiovascular disease. The results of this study will help to determine if B vitamins should be a part of the medical treatment of diabetic patients with elevated plasma homocysteine concentrations.