Abstract P311: Intracellular Renin Angiotensin Aldosterone System inMesangial Cells Under the Stimulus of Aldosterone

Abstract

Mesangial cells (MCs) are a local target for aldosterone (aldo) action in the modulation of the renin angiotensin aldosterone system (RAAS).Its molecular mechanisms is far from clear, and are extremely important in understanding renal pathologies. We investigated if the effect of aldosterone stimulus in supra, physiological and sub physiological doses was able to modulate the intracrine human MCs RAAS. We performed viability assays, western blot, immunofluorescence, ACE and ACE2 activities. As a result, we have obtained that the ACE activity was increased after MCs treatment with aldosterone 1 and 10 nM when compared with 0.1nM after 72h. Previous cells treatment with spirolactone followed by aldo reduced ACE catalytic activity but not ACE2. ACE and ACE 2 expression increased after 72h of MCs treatment with aldo 10 nM. The immunofluorescence showed that ACE was overexpressed in MCs after 72h with 10nM aldosterone treatment being similar to control group, differing from the treatment with spirolactone + aldo stimulation that decreased ACE expression, internalized Angiotensin II and changed the AT1 receptor localization. The same treatment increased MAS receptor production in MCs after 72h of aldosterone treatment with 10, 1.0, 0.1 and 0.01nM , but not with spirolactone + aldo treatment that inhibited receptor synthesis. ACE2 was detected in cell nucleus with 24h of treatment with aldo and in cytoplasm after 72h, being reduced after the treatment with spirolactone+aldo. Ang 1-7 was localized at cell nucleus and in cytoplasm after treatment with aldo 24h and 72h, decreasing with spirolactone + aldo treatment. Immunofluorescence results demonstrated that MCs pre-treated with spironolactone decreased ACE, ACE2 and MAS receptor expression, and altered ANG II localization, suggesting that spironolactone acts on the mineralocorticoid receptor internalizing ANG II into the nucleus, probably by AT1 and AT2 receptors pathways. These results demonstrated that aldosterone can modulate the local RAAS in mesangial cells suggesting that its physiological concentrations are necessary for the feasibility of these cells while high doses are cytotoxic and altered the local system.