Integrins as dynamic regulators of vascular function.

The vascular endothelium lines the entire cardiovascular system and serves as a nonthrombogenic and selectively permeable boundary between the blood-stream and extravascular space. Endothelial cells are polar cells that are continuously subjected to fluid-generated forces on their luminal surface whereas their abluminal surface resides on basement membranes/extracellular matrix. The integrin family of cell-surface heterodimeric glycoproteins is located along both of these surfaces and participates in maintaining the normal endothelium and in the dynamic changes associated with the pathophysiology of the endothelium. Endothelial cell beta 1 and beta 3 integrins function together with other families of adhesion molecules during vasculogenesis, angiogenesis, inflammation, and wound healing. Leukocyte beta 1 and beta 2 integrins, in conjunction with members of the Ig and selectin gene families expressed on endothelium, mediate leukocyte recruitment to sites of inflammation. The structural and functional properties of integrins make them uniquely suited to mediate these essential and complex processes in the vasculature.