Assessing and Improving Pancreatic Islet Viability and Function

点击翻译按钮获取中文摘要

DESCRIPTION (provided by applicant): The long-term goal of my lab is to identify and elucidate the mechanisms and causes of diabetes and metabolic disorders by investigating dysfunctions in islet physiology. Diabetes mellitus is a metabolic disease that results from either a complete or relative deficiency of the hormone insulin and currently affects 20.8 million people in the U.S. and is increasing in incidence. The cost of caring for this disease is enormous, exceeding 135 billion dollars annually. Increasing evidence suggests that inflammation and immune responses lead to the destruction of insulin-producing beta-cells in pancreatic islets not only in type 1 diabetes (T1DM), but that these factors also contribute to beta-cell loss in type 2 diabetes (T2DM) and other metabolic disorders. Although glucose-stimulated insulin secretion (GSIS) is the standard measure of islet function, preliminary data suggest a more sensitive indicator of islet dysfunction is intracellular calcium ([Ca2+]i), which is closely linked with insulin secretion. Preliminary data show that pro-inflammatory cytokines induce dysfunction in islet [Ca2+]i handling at much lower cytokine concentrations than required to negatively impact insulin secretion. The working model of this proposal is that deficiencies in endogenous [Ca2+]i oscillations and glucose-stimulated changes in [Ca2+]i are indicators of early stages of damage to islet function and viability. Benefits of genetic or pharmacologic interventions to prevent or reverse diabetes will be predicted by [Ca2+]i measurements. The aims of this proposal are to develop more sensitive and accurate methods of assessing islet health (aim1), determine mechanisms of inflammatory cytokine-induced islet dysfunction (aim2), and test novel anti-inflammatory treatments to improve islet health using both novel and standard methods (aim3). The specific aims of this proposal are designed, in part, to evaluate human islets for transplantation, however, the proposed studies will have far greater impact. Accurate, sensitive, and systematic evaluations of islet dysfunction will be used to identify early indicators of dysfunction at the islet level and to elucidate their mechanism in diseases such as T1DM and T2DM, as well as to assess potential therapies for diabetes at the islet level. In addition, the source(s) of dysfunctional calcium handling will also be investigated as a possible mechanism(s) of islet damage; chiefly ER-stress, glycolytic disruption, and ion channels will be examined using a combination of physiological, molecular, and genetic approaches.