2-chlorohexadecanal derived from hypochlorite-modified high-density lipoprotein-associated plasmalogen is a natural inhibitor of endothelial nitric oxide biosynthesis

Objective - Myeloperoxidase, a heme enzyme that is present and active in human atherosclerotic lesions, provides a source for the generation of proinflammatory chlorinated reactants contributing to endothelial dysfunction. Modification of high-density lipoprotein (HDL) by hypochlorous acid/hypochlorite (HOCl/Oce(-)) - generated in vivo by the myeloperoxidase-hydrogen peroxide-chloride system of activated phagocytes - forms a proatherogenic lipoprotein particle that binds to and is internalized by endothelial cells. Methods and Results - Here we show that HDL, modified with physiologically relevant HOCl concentrations, attenuates the expression and activity of vasculoprotective endothelial nitric oxide synthase. HOCl-HDL promotes dislocalization of endothelial nitric oxide synthase from the plasma membrane and perinuclear location of human umbilical venous endothelial cells. We could identify 2-chlorohexadecanal as the active component mediating this inhibitory activity. This chlorinated fatty aldehyde is formed during HOCl-mediated oxidative cleavage of HDL-associated plasmalogen. Conclusion - 2-Chlorohexadecanal, produced by the myeloperoxidase-hydrogen peroxide-chloride system of activated phagocytes may act as a mediator of vascular injury associated with ischemia-reperfusion injury, glomerulosclerosis, and atherosclerosis.