Accelerated vascular disease, involving both the micro- and macro-vasculature accompanies diabetes mellitus (both types I and II) and syndromes of insulin resistance. Nonenzymatic glycation of proteins and lipids occurs with hyperglycemia and is most marked in macromolecules with long turnover times, ultimately leading to formation of advanced glycation endproducts (AGEs). A principle means by which AGEs affect cellular properties is by interacting with binding proteins, the best characterized of which is receptor for AGEs (RAGE), a member of the immunoglobulin superfamily. Based on the applicant's pilot data, they hypothesize that engagement of RAGE by AGEs underlies changes in those cells critical to atherogenesis, especially endothelial cells and monocytes, affecting cell function in ways that predispose to the development of atherosclerosis and microvascular disease. The major goal of this project is to develop and utilize molecular tools allowing dissection of the contribution of RAGE to diabetic atherosclerosis.
Their specific aims are: (1) To develop transgenic (Tg) mice overexpressing sRAGE and RAGE gene knock-out (0) mice, in order to study the role of RAGE in hyperfibrinogenemia, elevated plasminogen activator inhibitor-I (PAI-I) and vascular hyperpermeability associated with diabetes; (2) to develop a diabetic murine model of accelerated atherosclerosis, and, using this model, to determine the contribution of RAGE to lesion formation. These experiments will initially employ apoE 0 mice rendered diabetic with streptozotocin, based on the applicant's pilot data showing more extensive atherosclerosis in these animals than in euglycemic apoE 0 mice, as well as cross-breeding with murine genetic models of diabetes. Tg mice overexpressing apoB, an excellent substrate for nonenzymatic glycation and oxidation, will also be used to develop an atherosclerosis/diabetes model. (3) To assess if AGE engagement of RAGE leading to increased plasma soluble (s) VCAM-1 antigen provides a marker of ongoing endothelial perturbation in diabetes. The impact of RAGE blockade and antioxidant therapy on plasma sVCAM-1 and indices of vascular dysfunction in experimental murine diabetes will be evaluated. Then, using optimal conditions from their murine study, a clinical trial of antioxidants will be undertaken in diabetic patients with microalbuminuria to determine the effect on sVCAM-1 and plasma markers of oxidant stress. The results of these experiments are directed towards our long-term goal, understanding mechanisms important in the pathogenesis of accelerated atherosclerosis in diabetes.
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