[Biology of the endothelial cell and atherogenesis].

Through their specific biological properties, vascular endothelial cells play a major role in maintaining the homeostasis of the cardiovascular system. The vascular endothelium participates actively in coagulation and fibrinolysis, contributes to regulating vascular tone, is involved in inflammation and immunological responses, produces several different stromal components, plays a crucial role in angiogenesis and wound-healing, and interacts with plasma lipoproteins. These physiological functions of endothelial cells are triggered by different endothelium derived mediators and are regulated by numerous environmental factors that can markedly modulate the functional state of these cells by affecting their biosynthetic capabilities, giving them different phenotypes in native, activated and injured states. Excessive endothelial activation leads to changes in endothelial cell gene expression, leading to what is referred to as a dysfunctional state. In this non-adaptative functional state, endothelial cells lose the ability to adjust, within the physiological range, some of their constitutive functions and express newly induced molecules, some of which act as proatherosclerotic factors. Activated endothelial cells thus participate actively in the pathogenesis of atherosclerosis.