MAS receptors mediate vasoprotective and atheroprotective effects of candesartan upon the recovery of vascular angiotensin-converting enzyme 2-angiotensin-(1-7)-MAS axis functionality

Abstract AT 1 antagonists effectively prevent atherosclerosis since AT 1 upregulation and angiotensin II-induced proinflammatory actions are critical to atherogenesis. Despite the classic mechanisms underlying the vasoprotective and atheroprotective actions of AT 1 antagonists, the cross-talk between angiotensin-converting enzyme-angiotensin II-AT 1 and angiotensin-converting enzyme 2–angiotensin-(1-7)–MAS axes suggests other mechanisms beyond AT 1 blockage in such effects. For instance, angiotensin-converting enzyme 2 activity is inhibited by reactive oxygen species derived from AT 1 -mediated proinflammatory signaling. Since angiotensin-(1-7) promotes antiatherogenic effects, we hypothesized that the vasoprotective and atheroprotective effects of AT 1 antagonists could result from their inhibitory effects on the AT 1 -mediated negative modulation of vascular angiotensin-converting enzyme 2–angiotensin-(1-7)–MAS axis functionality. Interestingly, our results showed that early atherosclerosis triggered in thoracic aorta from high cholesterol fed-Apolipoprotein E-deficient mice impairs angiotensin-converting enzyme 2–angiotensin-(1-7)–MAS axis functionality by a proinflammatory-redox AT 1 -mediated pathway. In such mechanism, AT 1 activation leads to the aortic release of tumor necrosis factor-α, which stimulates NAD(P)H oxidase/Nox1-driven generation of superoxide and hydrogen peroxide. While hydrogen peroxide inhibits angiotensin-converting enzyme 2 activity, superoxide impairs MAS functionality. Candesartan treatment restored the functionality of angiotensin-converting enzyme 2–angiotensin-(1-7)–MAS axis by inhibiting the proinflammatory-redox AT 1 -mediated mechanism. Candesartan also promoted vasoprotective and atheroprotective effects that were mediated by MAS since A779 (MAS antagonist) co-treatment inhibited them. The role of MAS receptors as the final mediators of the vasoprotective and atheroprotective effects of candesartan was supported by the vascular actions of angiotensin-(1-7) upon the recovery of the functionality of vascular angiotensin-converting enzyme 2–angiotensin-(1-7)–MAS axis.