Macrophage scavenger receptor class A - A multifunctional receptor in atherosclerosis

In atherogenesis, elevated plasma levels of low density lipoprotein (LDL) l ead to the chronic presence of LDL in the arterial wall. There, LDL is modi fied (eg, oxidized), and these modified lipoproteins activate endothelial c ells, which attract circulating monocytes. These monocytes enter the vessel wall, differentiate into macrophages, and subject the modified lipoprotein s to endocytosis through scavenger receptor pathways. This unrestricted upt ake, which is not limited by intracellular cholesterol levels, eventually l eads to the formation of lipid-filled foam cells, the initial step in ather osclerosis. Macrophage scavenger receptor class A (SRA) is thought to be on e of the main receptors involved in foam cell formation, mediating the infl ux of lipids into the macrophages. In addition to this role in modified lip oprotein uptake by macrophages. the SRA has been shown to be important in t he inflammatory response in host defense, cellular activation, adhesion, an d cell-cell interaction. Given the importance of these processes in atherog enesis, these latter functions may prove to make the SRA a multifunctional player in the atherosclerotic process.