Lipid peroxidation and endothelial cell injury: implications in atherosclerosis

Vascular endothelial cells, which play an active role in the physiological processes of vessel tone regulation and vascular permeability, form a border separating deeper layers of the blood vessel wall and cellular interstitial space from the blood and circulating cells. Damage or dysfunction of endothelial cells may reduce the effectiveness of the endothelium to act as a selectively permeable barrier to plasma components, including cholesterol-rich lipoprotein remnants. This may be involved in the etiology of atherosclerosis. Experimental evidence indicates that free radical-mediated lipid peroxidation can induce endothelial cell injury/dysfunction. Reactive oxygen species, including peroxidized lipids capable of initiating cell injury, may be generated within endothelial cells, be present in plasma components, or be derived from neutrophils or other blood-borne cells. Lipid peroxidation could initiate or promote the process of atherosclerotic lesion formation by directly damaging endothelial cells, and by enhancing the adhesion and activation of neutrophils and the susceptibility of platelets to aggregate. Endothelial cell injury by lipid hydroperoxides also could increase the uptake of LDL into the vessel wall. These events and other cellular dysfunctions may individually or collectively initiate and/or help to sustain the development of atherosclerosis.