KALLIKREINS-KININS AND DIABETIC VASCULAR COMPLICATIONS

Medical University Of South Carolina, Charleston SC

Investigators

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Abstract

DESCRIPTION (provided by applicant): The risk factors that contribute to the development of vascular disease in diabetes are not fully defined. Our objective in this application is to define the unique role of the kallikrein-kinin system (KKS) in the pathogenesis of vascular complications and to elucidate the underlying mechanisms involved in this process. Our hypothesis which is based on preliminary data generated from the DCCT/EDIC-cohort of type 1 diabetic patients, demonstrate, for the first time, an association between plasma prekallikrein levels and surrogate markers of macrovascular disease (internal and common carotid intima-medial wall thickness). IN addition, our data also demonstrates an association between KKS components and established vascular disease risk factors such as, hypertension, elevated lipids, microalbuminuria, fibrinogen and PAI1. Further, our data also demonstrates that KKS components positively correlate with the circulating levels of the prosclerotic factor connective tissue growth factor (cTGF). We have also discovered that there is a strong correlation between the circulating levels of cTGF and the excretion rate of albumin. Finally, our recent data at a cellular level indicates that kinins participate in the development of diabetic vascular injury by acting through their receptors to stimulate several key-signaling pathways that promote proliferation and/or sclerosis of vascular cells. In this regard, bradykinin (BK) stimulates the levels of collagen 1, cTGF and transforming growth factor-beta (TGF-beta) in vascular smooth muscle cells (VSMC). This increase in collagen 1 by BK was mediated via autocrine activation of TGF-beta. Moreover, the induction of TGF-beta by BK in VSMC was mediated via activation of the MAPK pathways. Therefore, we hypothesize that activation of the KKS components by the diabetic state plays a pivotal role in the initiation and progression of diabetic vascular disease. To test our hypothesis, we propose the following specific aims.1. Determine whether diabetic patients who develop vascular disease have markers of altered KKS activity, compared with patients who do not develop vascular disease. For these studies we will define the relationships of biomarkers of KKS components (plasma prekallikrein, kininogen, Factor XII) to indices of macrovascular disease in type 1 and type 2 diabetic patients. We will also identify novel polymorphisms to markers of vascular and renal dysfunction in diabetic patients.2. Determine the role and contribution of the KKS to modulate production of biomarkers of vascular and renal injury. For these studies, we will measure the circulating levels of TGF-beta and cTGF in type 1 and type 2 diabetic patients. We will define interrelationships between KKS and TGF-beta and cTGF, and determine whether TGF-beta and cTGF will predict the development of diabetic vascular complications. The effect of peroxisome proliferator-activated receptor-gamma (PPAR-gamma) activators on BK signaling to promote VSMC sclerosis will be examined. 3. Investigate if hyperglycemia will modulate the assembly and activation of KKS on endothelial cell surfaces. These studies will provide a comprehensive and critical assessment of the contribution of the KKS to diabetic vascular disease and will enhance our understanding of the multi-factorial mechanisms underlying vascular disease in diabetics.