Oxidized Low Density Lipoprotein (OxLDL)

Hypercholesterolemia is closely associated with increased risk of atherosclerosis. The cholesterol accumulated in the atherosclerotic plaque is derived primarily from low-density lipoprotein (LDL). Oxidation of LDL is now accepted as a critical event in the atherogenic process. Free radicals like superoxide and nitric oxide (-O2 , NO) generated in biological reactions in the body contribute to the oxidation of LDL. The NO radical has been shown to oxidize apolipoprotein B a constituant of LDL. Similarly, lipoxygenases and oxidants like peroxynitrite can oxidize the lipid moieties in LDL. It has been demonstrated that oxLDL and not native LDL is taken up by scavenger receptors on monocytes, smooth muscle cells and macrophages in the blood vessels. The oxidation of LDL increases the affinity of oxLDL to acetyl receptors of macrophages. As this pathway of oxLDL uptake is unregulated, it results in the formation of lipid-laden macrophages (foam cells).