Expression of lipoprotein receptors and related molecules in atherosclerotic lesions.

Atherosclerotic lesions are characterized by the presence of lipid-loaded cells that are derived from monocyte/macrophages and smooth muscle cells. At least four major lipoprotein receptors have been characterized that could be involved in arterial lipid uptake. These receptors include: scavenger receptor(s), the LDL receptor-related protein/alpha 2-macroglobulin receptor, the LDL receptor and the VLDL receptor. With the exception of the LDL receptor, all of these receptors are expressed in atherosclerotic lesions. Whereas scavenger receptors are mostly expressed in macrophages, the LDL receptor-related protein may play an important role in mediating lipid uptake in smooth muscle cells. It appears that no single receptor pathway is solely responsible for the increased lipid uptake in lesion cells, but several redundant mechanisms may contribute to the uptake and degradation of lipoproteins in atherosclerotic lesions.