Structure, fonction biologique et utilité clinique des angiopoiétines 1 et 2 dans l’exploration de la dysfonction endothéliale

Abstract

Angiopoietins 1 and 2 (Ang-1 and Ang-2) and their associated receptors Tie1 and Tie2 represent an extremely fine regulatory system of vascular endothelium. Ang-1, secreted in the endothelial microenvironment by pericytes, is a Tie2 receptor agonist with multiple protective vascular effects. In contrast, Ang-2 secreted mainly by endothelial cells, blocks the signaling pathway induced by the Tie2 receptor and antagonizes the effects of Ang-1 which has the consequence of destabilizing the vascular endothelium. The Ang-2/Ang-1 ratio is therefore a key element in the regulation of endothelial function. All pathophysiological situations capable of modulating this ratio either by increasing the production of Ang-2 or by decreasing that of Ang-1 could thus induce an endothelial dysfunction. This is what is observed during acute inflammatory state as sepsis or chronic inflammation as in cardiovascular disease. The measurements of circulating concentrations of Ang-1 and Ang-2 could potentially constitute a good biological marker of endothelial dysfunction. The main objectives of this review are to describe the structure and the different biological activities at the vascular level of angiopoietins and to present the different clinical and biological studies in which the circulating concentrations of angiopoietins have proven to be reliable biological markers of endothelial dysfunction.