DESCRIPTION (provided by applicant): The presence of two 15-lipoxygenases (15-LOXs), namely, 15-LOX1 and 15-LOX2, has been reported in humans. 15-LOX1 while preferentially metabolizes linoleic acid (LA) to 13(S)-hydroxyoctadecadienoic acid (13(S)-HODE) also converts arachidonic acid (AA) to 15-hydroxyeicosatetraenoic acid (15(S)-HETE) and 12(S)-hydroxyeicosatetraenoic acid (12(S)-HETE). On the other hand, 15-LOX2 specifically metabolizes AA to 15(S)-HETE. In regard to their tissue distribution, 15-LOX1 has been shown to be present in a wide variety of cell types including reticulocytes, macrophages and monocytes, whereas the expression of 15-LOX2 appears to be restricted to epithelial cell types in cornea, lung, prostate and skin. Although the presence of 15-LOX2 in the vessel wall has not been reported yet, vascular smooth muscle cells (VSMC) and endothelial cells (EC) express 15-LOX1 (also known as 12/15-LOX in murines) and when these cells are exposed to AA, they produce both 15(S)-HETE and 12(S)-HETE. Although, the involvement of 12(S)-HETE in vascular diseases has been fairly studied, relatively nothing is known about the role of 15(S)-HETE. In this aspect, the work in our laboratory pointed out that 15(S)-HETE is a potent stimulator of angiogenesis. Since angiogenesis plays a crucial role in vascular diseases, it is essential to investigate whether 15-LOX-15(S)-HETE axis, via inducing angiogenesis, influences vascular diseases. Towards achieving this goal, we propose to study the following five specific aims. Specific Aim 1: To determine the role of Egr-1 in 15(S)-HETE-induced human dermal micro vascular endothelial cell (HDMVEC) migration and tube formation and aortic ring and Matrigel plug angiogenesis. Specific Aim 2: 15(S)-HETE-induced HDMVEC migration and tube formation and aortic ring and Matrigel plug angiogenesis require Egr-1-mediated induction of expression of fibroblast growth factor (FGF)-2 and vascular endothelial growth factor (VEGF). Specific Aim 3: 15(S)-HETE-induced HDMVEC migration and tube formation and aortic ring and Matrigel plug angiogenesis require 3-hydroxy-3-methyl glutaryl coenzyme-A reductase (HMGCR) activity. Specific Aim 4: 15(S)-HETE-induced HDMVEC migration and tube formation and aortic ring and Matrigel plug angiogenesis require HMGCR-dependent expression and release of matrix metalloproteinases (MMP)-2 and -9. Specific Aim 5: Inhibition of 12/15-LOX reduces intraplaque angiogenesis and atherosclerotic lesions. The results of the experiments proposed in the above-listed five specific aims will provide novel information in terms of the role of 15-LOX-15(S)-HETE axis in vascular diseases and the potential new mechanisms by which this lipid molecule exerts such vascular wall remodeling.

PUBLIC HEALTH RELEVANCE Angiogenesis plays a major role in inflammatory cardiovascular diseases such as atherosclerosis. Understanding the mechanisms underlying angiogenesis is, therefore, crucial in the development of therapeutic agents against these vascular lesions. The present research proposal seeks to study the role of 15-LOX-15(S)-HETE axis in intraplaque angiogenesis and thereby in the progression of atherosclerosis.