Ang II Upregulates Macrophage MMP-2 Activity to Facilitate Entry of this Cell Type into Arterial Tissue

My sponsor's laboratory has previouslydemonstratedthat infusion of angiotensin II (Angll) promotes the formation of abdominal aortic aneurysms in hyperlipdemic mice. As described in thl~ body of this application, we have evidence from pharmacological studies that the formation is due to the activity of matrix metalloproteinases (MMPs). More specifically, I have recently generated data showing that ablation of MMP-2 in bone marrow derived cells attenuates the development of Angll-induced AAA. Based on studies that define the sequence of cellular changes in the formation of AAA, it appears that macrophagles are the primary bone marrow derived cell type involved in the disease process. Therefore, I am proposing to test the hypothesis that Angll upregulates macrophage MMP-2 activity to facilitate entry of this cell type into arterial tissues. To test this hypothesis, I am proposing the following specific aims: Specific Aim 1. Determine whether Angll regulates the synthesis and catabolism of IVIMP-2 in macrophages. A. Determine the effect of Angll on the abundance of MMP-2 mRNA and protein. B. Determine the contribution of specific Angll receptors (AT1 and AT2) on the synthesis of MMP-2. C. Determine the contribution of Angll on the catabolism of MMP-2 with particular emphasis on the role of LRP (low density lipoprotein receptor related protein, also termed the alpha2 macroglobulin receptor). Specific Aim 2. Determine the ability of Angll to regulate factors that modify the activation of MMP-2. A. Determine the effect of Angll on the abundance of MT-MMP-1 (also termed MMP-14) and tissue inhibitor of matrix metalloproteinase-2 (TIMP-2) in cultured macrophages. B. Determine the role of Angll on MMP-2 activation via urokinase plasminogen activator (uPA) acting directly or via the generation of plasmin. Specific Aim 3. Determine the role of MMP-2 in facilitating entry of macrophages into extracellular matrix (ECM) and define whether Angll augments the entry. A. Determine the role of MMP-2 in macrophage entry into extracellular matrix using IVIMP-2deficient mice. B. Determine whether Angll facilitates MMP-2 mediated matrix penetration of macrophages.