Olmesartan Attenuates Kidney Fibrosis in a Murine Model of Alport Syndrome by Suppressing Tubular Expression of TGF?.

ABSTRACT: Despite the wide use of angiotensin II receptor blockers in the treatment of Alport syndrome (AS), the mechanism as to how angiotensin II receptor blockers prevent interstitial fibrosis remains unclear. Here, we report that treatment of olmesartan effectively targets the feedback loop between the renin-angiotensin system (RAS) and transforming growth factor ? (TGF?) signals in tubular epithelial cells and preserves renal angiotensin-converting enzyme 2 (ACE2) expression in the kidney of Col4a3-/- mice, a murine model of experimental AS. Morphology analyses revealed amelioration of kidney fibrosis in Col4a3-/- mice by olmesartan treatment. Upregulation of TGF? and activation of its downstream in Col4a3-/- mice were attenuated by olmesartan in Col4a3-/- mice. Intriguingly, TGF? expression was preferentially upregulated in damaged tubular epithelial cells in Col4a3-/- mice. Concurrent upregulation of TNF?-converting enzyme and downregulation of ACE2 suggested RAS activation in Col4a3-/- mice, which was prevented by olmesartan. Mechanistically, olmesartan suppressed TGF?-induced RAS activation in tubular epithelial cells in vitro. Collectively, we concluded that olmesartan effectively suppresses the progression of tubulointerstitial fibrosis in AS by interrupting RAS-TGF? feedback loop to counterbalance intrarenal RAS activation.

SUBMITTER: Suh SH 

PROVIDER: S-EPMC6695622 | biostudies-literature | 2019 Aug

REPOSITORIES: biostudies-literature