MPO-modified high-density lipoprotein and receptors

The vascular endothelium is a wide spread organ responsible for the regulation of hemodynamics, angiogenic vascular remodeling, metabolic, synthetic, antiinflammatory, and antithrombogenic processes. Diminished nitric oxide (NO) availability has been linked to vascular disease and a heightened state of inflammation is characterized, in part, by an increase in vascular myeloperoxidase and proteins in vivo modified by its principal oxidant, hypochlorous acid/hypochlorite (HOCl/OCl- ). Modification of high-density lipoprotein (HDL) by HOCl generates a proatherogenic and proinflammatory lipoprotein particle. HOCl-HDL, present in human lesions material and on endothelial cells, attenuates the expression and activity of vasculoprotective endothelial NO synthase (eNOS). Therefore, one part of this application is to clarify the mechanisms that governs interaction of HOCl-HDL and its lipid(plasmalogen)-derived oxidant 2-chlorohexadecanal with eNOS, to focus whether caveolae-located proteins are involved, to profile alterations in endothelial gene expression patterns, and to investigate endothelium- dependent vascular relaxation in aortic rings and perfused vessels. As endothelial dysfunction may be induced by receptor-ligand interaction, the other part of this application will focus on interaction of HOCl-HDL with candidate receptors mediating (patho)physiologically relevant cellular responses, i.e. activation of transcription factors, kinases, and production of cytokines, leading to the perpetuation of the inflammatory response and endothelial dysfunction. To answer these questions cell lines overexpressing candidate receptors will be used before adapting the cellular signaling cascade patterns to a specific endothelial cell line. We propose that myeloperoxidase- modified HDL - a unique and clinically significant marker for atherosclerosis - mediates endothelial dysfunction by specific receptor-evoked intracellular signaling pathways. Specific aims for testing the hypothesis are: 1. Multiligand-receptor (SR-BI and RAGE)-mediated intracellular signaling transduction in response to HOCl- HDL. 2. To investigate the direct interaction of HOCl-HDL/2-chlorohexadecanal with eNOS, their effects on relaxation in aortic rings and perfused vessels from murine tissues (SR-BI -/- mice), and to analyze alterations in gene expression. 3. Toll-like receptor (TLR2 and TLR4)-mediated signaling transduction and secretion of inflammatory mediators in response to HOCl-HDL. We believe that the outcome of this proposal will provide new and useful information to understand biological properties of cells during development of atherosclerosis and inflammation when exposed to a proatherogenic lipoprotein species occuring in vivo.

The vascular endothelium is a wide spread organ responsible for the regulation of hemodynamics, angiogenic vascular remodeling, metabolic, synthetic, antiinflammatory, and antithrombogenic processes. Diminished nitric oxide (NO) availability has been linked to vascular disease and a heightened state of inflammation is characterized, in part, by an increase in vascular myeloperoxidase and proteins in vivo modified by its principal oxidant, hypochlorous acid/hypochlorite (HOCl/OCl- ). Modification of high-density lipoprotein (HDL) by HOCl generates a proatherogenic and proinflammatory lipoprotein particle. HOCl-HDL, present in human lesions material and on endothelial cells, attenuates the expression and activity of vasculoprotective endothelial NO synthase (eNOS). Therefore, one part of this application is to clarify the mechanisms that governs interaction of HOCl-HDL and its lipid(plasmalogen)-derived oxidant 2-chlorohexadecanal with eNOS, to focus whether caveolae-located proteins are involved, to profile alterations in endothelial gene expression patterns, and to investigate endothelium- dependent vascular relaxation in aortic rings and perfused vessels. As endothelial dysfunction may be induced by receptor-ligand interaction, the other part of this application will focus on interaction of HOCl-HDL with candidate receptors mediating (patho)physiologically relevant cellular responses, i.e. activation of transcription factors, kinases, and production of cytokines, leading to the perpetuation of the inflammatory response and endothelial dysfunction. To answer these questions cell lines overexpressing candidate receptors will be used before adapting the cellular signaling cascade patterns to a specific endothelial cell line. We propose that myeloperoxidase- modified HDL - a unique and clinically significant marker for atherosclerosis - mediates endothelial dysfunction by specific receptor-evoked intracellular signaling pathways. Specific aims for testing the hypothesis are: 1. Multiligand-receptor (SR-BI and RAGE)-mediated intracellular signaling transduction in response to HOCl- HDL. 2. To investigate the direct interaction of HOCl-HDL/2-chlorohexadecanal with eNOS, their effects on relaxation in aortic rings and perfused vessels from murine tissues (SR-BI - / - mice), and to analyze alterations in gene expression. 3. Toll-like receptor (TLR2 and TLR4)-mediated signaling transduction and secretion of inflammatory mediators in response to HOCl-HDL. We believe that the outcome of this proposal will provide new and useful information to understand biological properties of cells during development of atherosclerosis and inflammation when exposed to a proatherogenic lipoprotein species occuring in vivo.