Human carotid artery smooth muscle cells rarely express alpha(v)beta3 integrin at sites of recent plaque rupture

Fibrin(ogen) is the major matrix ligand for beta3 integrins. If alpha(v)beta3 is the major receptor for fibrin(ogen) on intimal smooth muscle cells, we might expect to see this integrin associated with fibrin(ogen). Eighty-four specimens obtained from endarterectomies of 14 patients were studied. Fibrin was frequently observed in carotid intima even at the non-atherosclerotic areas. As for beta1 and beta3 integrins, beta1 was predominant in intima. The alpha(v)beta3 integrin expression was less frequent than alpha5beta1, another receptor for fibrin(ogen), in diffuse intimal thickening, fibrous cap and advanced plaques. Furthermore, alpha(v)beta3 was generally negative on smooth muscle cells in recent plaque ruptures. In conclusion, we suggest more attention should be paid on abundant fibrin matrix in intima. Histologically, the alpha5beta1 integrin rather than the alpha(v)beta3 is the major receptor for fibrin in intimal smooth muscle cells.