EXPRESSION OF VERY-LOW-DENSITY LIPOPROTEIN RECEPTOR IN THE VASCULAR WALL - ANALYSIS OF HUMAN TISSUES BY IN-SITU HYBRIDIZATION AND IMMUNOHISTOCHEMISTRY

The recently cloned very low density lipoprotein (VLDL) receptor binds triglyceride-rich, apolipoprotein-E-containing lipoproteins with high affinity. The observation that VLDL receptor mRNA is abundantly expre ssed in extracts of tissues such as skeletal muscle and heart, but not liver, has led to the hypothesis that this receptor may facilitate th e peripheral uptake of triglyceride-rich lipoproteins. However, little information is available concerning the types of cells that express t his receptor in vivo. As expression of the VLDL receptor in the vascul ar wall might have important implications for the uptake and transport of triglyceride-rick lipoproteins, and perhaps facilitate the develop ment of atherosclerosis in hypertriglyceridemic individuals, we used i n situ hybridization and immunohistochemistry to determine whether VLD L receptor mRNA and protein was expressed in human vascular tissue. We observed expression of the receptor by both endothelial and smooth mu scle cells within normal arteries and veins, as well as within atheros clerotic plaques. In the latter, the VLDL receptor was also expressed by macrophage-derived foam cells. The widespread distribution of the V LDL receptor in vascular tissue suggests a potentially important role for this receptor in normal and pathophysiological vascular processes.