Influence of High Glucose on Endothelial Function

Identifying and intervening molecular pathways that directly contribute to vascular complications will have a significant clinical impact in preventinginsulin dependent diabetes mellitus (IDDM)-associated vascular complications. We hypothesize that impaired physiological repair mechanisms due to altered endothelium- derived relaxation factor (nitric oxide) signaling pathway mediated by sustained high glucose is responsible for vascular complications. Under normal physiological condition, interaction of heat shock protein (Hsp-86) with endothelial nitric oxide synthase (NOS III) is responsible for nitric oxide-dependent endothelial functions. However, under high glucose condition, there is an enhanced inhibitor kB kinase activity (IKK-2), which competes out NOS lll from binding to Hsp-86. Further IKK-2 binding phosphorylates Hsp-86. This sequence of events lead to inadequate availability of Hsp-86 to NOS III, which decelerates NOS lll activity with a final outcome of integrin-focal adhesion disassembly, delayed endothelial migration and poor vascular repair. Blocking IKK-2 with genetic or pharmacological inhibitors in combination with agents, which are already in clinical practice, may open new avenues to improve nitric oxide production and reduce vascular damage in IDDM patients. The proposed study constitutes innovative approaches with the use of in vitro cell culture based assays using mammalian aortic endothelial cells. Use of genetically-induced diabetic animal model and optimized arterial injury procedures further complement the in vitro mechanistic approach. The specific aims are: Aim 1 will investigate the competitive cross talk between NOS III and IKK-2 with Hsp-86 under the influence of high glucose. The effect of sequentially altered nitric oxide signaling pathway on endothelial migration will be evaluated. Aim 2 will determine in vivo, the contribution of Hsp-86 - IKK-2 cross talk in NOS lll dysregulation in Type-1 mouse model. Aim 3 will evaluate the potentials of blocking IKK-2 independently or in combination with L-arginine in improving endothelial repair mechanism in response to arterial injury. The knowledge gained will help to identify new avenues that will improve the current treatment modalities aimed to prevent or minimize the severity of vascular complications of IDDM patients. PUBLIC HEALTH RELEVANCE: Diabetes-associated vascular damage is responsible for the higher mortality of diabetic patients. Results of this study will identify effective therapeutic approaches to prevent or reduce vascular damage and improve their health and standard of living.