Possible involvement of angiotensin-converting enzyme 2 and Mas activation in inhibitory effects of angiotensin II Type 1 receptor blockade on vascular remodeling

We explored the roles of angiotensin-converting enzyme 2 (ACE2), angiotensin-(1-7), and Mas activation in angiotensin II type 1 receptor blockade-mediated attenuation of vascular remodeling. Vascular injury was induced by polyethylene-cuff placement around the mouse femoral artery. After cuff placement, the mRNA level of both ACE2 and Mas was markedly decreased in wild-type mice, whereas ACE mRNA was not changed. Immunostaining of ACE2 and Mas was observed mainly in the media and was reduced in the injured artery. Administration of angiotensin-(1-7) decreased neointimal formation after cuff placement, whereas administration of [D-Ala(7)] angiotensin-(1-7), a Mas antagonist, increased it. Consistent with these results, we also demonstrated that neointimal formation induced by cuff placement was further increased in ACE2 knockout mice. In angiotensin II type 1a receptor knockout mice, mRNA expression and immunostaining of ACE2 and Mas in the injured artery were greater, with less neointimal formation than in wild-type mice. Increased ACE2 expression in the injured artery was also observed by treatment of wild-type mice with an angiotensin II type 1 receptor blocker, olmesartan. These results suggested that activation of the ACE2-angiotensin-(1-7)-Mas axis is at least partly involved in the beneficial effects of angiotensin II type 1 receptor blockade on vascular remodeling.