Losartan Prevents Tubulointerstitial Fibrosis And Epithelial-to-Mesenchymal Transition In Vivo And In Vitro

Background and aims: Losartan had been proven to be protective in chronic kidneydisease, but whether it can inhibit Tubular epithelial-to-mesenchymal transition (EMT)and its possible mechanism were still uncertain. Here we investigated the effects oflosartan on tubulointerstitial fibrosis（TIF）and epithelial-to-mesenchymal transition(EMT) with unilateral ureteral obstruction (UUO) rat model in vivo and transforminggrowth factor (TGF-β1)-induced EMT of HK-2cells in vitro. Our study aimed atobserving the inhibitory effect of losartan on tubulointerstitial fibrosis as well asexploring its possible mechanism.Methods: Fifty SD rats were random divided into three groups: sham operation (n=10),UUO model (n=20) and UUO with losartan treatment (n=20). Losartan was given at adose of20mg/kg body weight per day by gavage after the surgery, the sham operationgroup and UUO group rats were received the same volume of saline solution. Rats weresacrificed7and14days after the surgery. The phenotype changes of HK-2cells wereinduced by TGF-β1and intervened with rat serum containing losartan in vitro. Theacquirement of rat serum containing losartan was performed using an establishedprocedure. Expression of E-cadherin, Vimentin, α-SMA, β-catenin and ZEB1in ratkidney tissue and HK-2cells was detected by immunofluorescence staining and Westernblot.Results: In vivo, the renal pathological changes and TIF were lighter in losartan treatedUUO rats compared with UUO models and losartan can partly maintain the expressionof E-cadherin and suppress expression of Vimentin, α-SMA, β-catenin and ZEB1atdifferent time. In vitro, losartan could inhibit myofibroblast phenotype of HK-2cellinduced by TGF-β1and maintain the epithelial phenotype of HK-2cell to some extent. Losatan could inhibit down-regulation of E-cadherin and up-regulation of Vimentin inHK-2cells induced by TGF-β1. It also could inhibit the localization of β-catenin incytoplasm and nucleus and suppress the up-regulation of ZEB1in HK-2cells inducedby TGF-β1. Finally, we used the LC-MS/MS method to detect the components in ratserum containing losartan, showing losartan matrix mediam3176.52ng/ml and its twometabolites EXP31742586.77ng/ml, EXP3179290.43ng/ml.Conclusion: These results suggest that losartan inhibits TIF in vivo and prevents tubularEMT in vitro, possibly through inhibitingβ-catenin/ZEB1pathway.