Chronic Endothelial Injury Hypothesis - The Role of Oxidized LDL

The Role of Oxidized LDL

Once LDL accumulates in the subendothelial space, it tends to become modified or oxidized. This oxidized LDL plays several key roles in furthering the course of the inflammatory process. It is chemotactic to monocytes; oxidized LDL causes endothelial cells to secrete molecules that cause monocytes to penetrate between the endothelial cells and accumulate in the intima.

Oxidized LDL promotes death of endothelial cells by augmenting apoptosis. Also, through the activation of collagenases, ox-LDL contributes to a process which may lead to the rupture of the fibrous plaque Oxidized LDL decreases the availability of endothelial nitric oxide (NO), which, in turn, increases the adhesion of monocytes to the endothelium. Moreover, NO is involved in paracrine signalling between the endothelium and the smooth muscle that maintains vascular tone; without it, the muscle will not relax, and the blood vessel remains constricted. Thus, oxidized LDL also contributes to the hypertension often seen with atherosclerosis.