HYPERTENSION AND ARTERIAL INJURY--A ROLE FOR INTEGRINS

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The overall goal of this project is to test the prevailing hypothesis that hypertension and arteriosclerosis may be linked through a mechanism that involves oxidative stress. Our working hypothesis is that oxidative stress in hypertension and atherosclerosis acts to induce similar alterations in the expression of specific integrins and extracellular matrix (ECM) proteins that are responsible for changes in vasomotor function and vascular smooth muscle (VSM) phenotype. Our recent studies have established a novel link between VSM and endothelial integrins and the control of vascular tone. In addition, preliminary data indicates that oxidative stress can alter the expression of at least one of the VSM integrins linked to vasomotor activity and an ECM protein that is a ligand for this receptor. These altered integrin/matrix interactions may predispose the arterial wall to development of vascular pathology. This project incorporates a model of renal hypertension and atherogenesis that will be studied at various stages of disease development in large, intermediate and microvascular sized arterial vessels. Assessments will be made of the redox status, integrin and ECM profiles and vascular reactivity to soluble and insoluble integrin-binding ligands. These ligands will include synthetic Arginine-Glycine-Aspartic Acid (RGD) containing peptides and type I collagen and osteopontin, which are up-regulated following vascular injury. Our strategy is combining studies of intact vessels, cellular, biochemical and molecular approaches will provide a powerful approach for testing our hypothesis and systematically integrating our results, The specific aims are: Aim 1: Characterize the vasomotor response for large intermediate and small arterial vessels to known integrin-binding peptides, type I collagen and osteopontin at varius stages of development for a rat model of renal hypertension and/or imposed oxidative stress (allylamine treated). Vasoactivity will be correlated with measurements of redox status and integrin/ECM profiles. Aim 2: Characterize the vascular redox status and mechanisms leading to the development of oxidative stress in models of renal hypertension and atherogenesis and evaluate the role of NFkappaB as a common signal transduction pathway. Aim 3. Characterize and evaluate changes in vascular ECM/integrin expression at the gene and protein levels that are associated with renal hypertension or oxidative stress and to define the influence of oxidative stress on extracellular matrix and integrin gene expression. These studies will provide new information that will advance our understanding vascular function in hypertension and atherosclerosis.