Therapeutic Approaches for Treatment of Diabetic Complications of Heart and Vascular Diseases

National Institute On Aging

Investigators

Abstract

The broad objective of this program is to perform preclinical experimentation on animal models of diabetes with myocardial ischemia and subsequent CHF or with hind limb ischemia to elucidate the mechanisms of diabetic cardiomyopathy and peripheral artery diseases to evaluate the potential of different therapeutic modalities to prevent or attenuate the development of CHF and diabetic foot in diabetic patients. I. AMP-activated Protein Kinase (AMPK) in Regulation of Cardiac Metabolism and Function in Diabetes Diabetic cardiomyopathy is a deadly ventricular dysfunction caused by abnormal glucose metabolism in diabetic patients. AMPK is, as a major energy sensor, responsible for glucose metabolism in heart. Hence, the roles of AMPK mechanism in diabetic cardiomyopathy are not completely clear. The goal of this project is to elucidate the role of AMPK in hyperglycemic damage to the heart and its relationship with insulin desensitization in cardiomyocytes. Specific aims are: 1) the changes in AMPK activity in response to hyperglycemia; 2) the role in insulin desensitization and formation of glucose granules in diabetic hearts; and 3) whether manipulations of AMPK or subtypes can improve glucose intake and metabolism. For this purpose, we start to breed transgenic AMPK gamma2 subunit knock-in and knock-out mouse strains in our lab. Those transgenic mouse strains and their respective wild-type counterparts will be subjected to coronary artery ligation or femoral artery ligation after they developed diabetes through STZ injections. Upon completion of this project, it will provide novel targets in AMPK signaling system that can be pharmacologically manipulated for prevention and treatment of diabetic complications of heart and vascular diseases. II. The receptor for advanced glycation end-products (RAGE) RAGE and its soluble forms of RAGE (sRAGE) are the emerging mechanisms that involve in the pathobiology of a wide range of diseases including cardiovascular diseases and diabetes. Hence, the role of sRAGE in diabetic cardiomyopathy and diabetic limb diseases are not clear. Experimental data suggest that sRAGE may neutralize the ligand-mediated damage by acting as a decoy. We tested whether sRAGE is cardio protective against myocardial acute ischemic injury. In an experimental model of myocardial infarction induced by permanent ligation of a coronary artery in rats, a single bolus injection of 1ug/kg of sRAGE immediately after coronary ligation, reduced myocardial infarction (MI) measured 24 h after coronary ligation by 50% compared to saline injection. For this purpose, we start to breed transgenic sRAGE+/RAGE- mouse strain and its cross-breed with ApoE-/- transgenic mouse which is prone to develop aortic aneurism, in our lab. Those transgenic mouse strains and their respective wild-type counterparts will be subjected to coronary artery ligation or femoral artery ligation after they developed diabetes through STZ injections. Upon completion of this project, it will provide proof of concept that sRAGE can be used for prevention and treatment of diabetic complications of heart and vascular diseases.