[Hyperlipidemia and atherosclerosis]

One of the critical events in the early stage of atherosclerosis is the focal accumulation of lipid-laden foam cells derived from macrophages. In various cholesterol-fed animal models of atherosclerosis, it was found that localized attachment of circulating monocytes to arterial endothelial cells appears to precede the formation of foam cells. It has been suggested that monocyte recruitment into early lesions is depend upon the endothelial adhesiveness for monocytes and lymphocytes. In vivo and in vitro experiments have identified molecules, such as ICAM-1, VCAM-1 and P-selecin, those can support the adhesion of monocytes and lymphocytes. Moreover oxidized LDL, lysophosphatidylcholine and oxidized fatty acids induce the expression of not only these adhesion molecules but also scavenger receptors, such as CD-36, SR-A and LOX-1. Recently we isolated and characterized the novel receptors for oxidized LDL, named LOX-1 and SR-PSOX. The expression of LOX-1 is found on endothelial cells, smooth muscle cells and macrophages. Whereas SR-PSOX expresses on macrophages. We address in this paper on the significance of hyperlipidemia, especially oxidized LDL and its receptors in terms of atherosclerosis.