Augmented endothelial uptake of oxidized low-density lipoprotein in response to endothelin-1.

Endothelin-1 (ET-1) may be involved in the development and progression of atherosclerosis. Furthermore, endothelin receptor blockade was shown to reduce the formation of atherosclerotic lesions in experimental studies. Another potent pro-atherosclerotic risk factor is oxidized low-density lipoprotein (oxLDL). Endothelial cells mediate the uptake of oxLDL by the recently identified lectin-like oxLDL receptor-1 (LOX-1), which accumulates in atherosclerotic lesions. In the present study, we analysed the effects of ET-1 on oxLDL uptake and LOX-1 expression in primary cultures of human umbilical vein endothelial cells (HUVEC). ET-1 stimulated uptake of oxLDL in HUVEC, which reached a maximum after 1 h. In further studies, we found a similar induction of LOX-1 mRNA and protein expression in response to ET-1. The augmented oxLDL uptake and the increased LOX-1 expression in response to ET-1 are mediated by the endothelin receptor B. Our data support a new pathophysiological mechanism by which locally and systemically increased ET-1 levels, e.g. in hypertensive patients, could promote LOX-1-mediated oxLDL uptake in human endothelial cells. This mechanism could promote the development and progression of endothelial dysfunction and atherosclerosis. In addition, endothelin receptor blockade could be considered as a new anti-atherosclerotic therapeutic principle.