Low- and high-density lipoproteins as hormonal regulators of platelet, vascular endothelial and smooth muscle cell interactions: relevance to hypertension

Abstract

The major risk factors for cardiovascular disease include hypertension, hyperlipidemia, hyperinsulinemia and smoking. They promote the development of atherosclerosis and thromboembolic complications, i.e. strokes and heart attacks. There are diverse interactions between these factors, the outstanding common denominator being alterations in serum lipoproteins, mainly elevated low-density lipoprotein (LDL)-cholesterol and reduced high-density lipoprotein (HDL)-cholesterol concentrations, which results in disturbed cholesterol homeostasis (transport and metabolism) and eventually in perturbations of cellular integrity/function. In addition to their roles as cholesterol-transporting molecules, LDL and HDL directly influence inter- and intracellular communication via stimulation of pivotal signal transduction processes. The 'hormonal' effects of LDL on platelets, endothelial cells and vascular smooth muscle cells are potentially harmful, whereas the effects of HDL may be protective in as much as HDL can antagonize LDL-mediated stimulation of cells. Therapy aimed at reducing serum LDL-cholesterol levels and increasing HDL-cholesterol levels will have multifactorial beneficial effects on cardiovascular disease.