Xiaoli Wu1,2, Xiaoqiang Ding3,4,5,6,7, Zhishan Ding1, Ping Jia3,4,5,6,7. 1. College of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou, China. 2. Traditional Chinese Medicine Pharmacology Laboratory, Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China. 3. Department of Nephrology, Zhongshan Hospital, Fudan University, Shanghai, China. 4. Shanghai Medical Center of Kidney, Shanghai, China. 5. Shanghai Institute of Kidney and Dialysis, Shanghai, China. 6. Shanghai Key Laboratory of Kidney and Blood Purification, Shanghai, China. 7. Hemodialysis quality control center of Shanghai, Shanghai, China.
Abstract
BACKGROUND/AIMS: Renal tubulointerstitial fibrosis is the most common pathway of progressive kidney injury, leading to end-stage renal disease. At present, no effective prophylactic treatment method is available. This study investigated the anti-fibrotic effects of total flavonoids (TFs) extracted from leaves of Carya Cathayensis in vivo and in vitro, and explored the underlying mechanisms. METHODS: Anti-fibrotic effects of TFs were measured using a mouse model of unilateral ureteral obstruction (UUO) and in transforming growth factor-β1 (TGF-β1)-treated mouse tubular epithelial cells (mTECs). mRNA expression and protein levels of Collagen I, Collagen III, and α-smooth muscle actin (α-SMA) were also tested by real-time reverse transcription PCR and western blot analysis. To elucidate the underlying mechanisms, expression of miR-21 was examined in mTECs treated with TFs using miR-21 mimics transfected into mTECs before TGF-β1 and TFs treatment. Regulation of mothers against decapentaplegic homolog (Smad) signaling by miR-21 was subsequently validated via overexpression and deletion of miR-21 followed by a luciferase assay. RESULTS: TFs treatment attenuated renal fibrosis, and inhibited expression of collagens and α-SMA in the kidneys of mice subjected to UUO. In vitro, the TFs significantly decreased expression of fibrotic markers in TGF-β1-treated mTECs. Moreover, TFs reduced miR-21 expression in a time- and dose-dependent manner in mTECs, increased expression of Smad7, and decreased phosphorylation of Smad3. Treatment with miR-21 mimics abolished the anti-fibrotic effects of the TFs on the TGF-β1-treated mTECs. In addition, genetic deletion of miR-21 upregulated expression of Smad7 and suppressed phosphorylation of Smad3, attenuating renal fibrosis in mice. Bioinformatics predictions revealed the potential binding site of miR-21 in the 3'-untranslated region of Smad7, and this was further confirmed by the luciferase assay. CONCLUSION: TFs ameliorate renal fibrosis via a miR-21/Smad7 signaling pathway, indicating a potential therapy for the prevention of renal fibrosis.
BACKGROUND/AIMS: Renal tubulointerstitial fibrosis is the most common pathway of progressive kidney injury, leading to end-stage renal disease. At present, no effective prophylactic treatment method is available. This study investigated the anti-fibrotic effects of total flavonoids (TFs) extracted from leaves of Carya Cathayensis in vivo and in vitro, and explored the underlying mechanisms. METHODS: Anti-fibrotic effects of TFs were measured using a mouse model of unilateral ureteral obstruction (UUO) and in transforming growth factor-β1 (TGF-β1)-treated mouse tubular epithelial cells (mTECs). mRNA expression and protein levels of Collagen I, Collagen III, and α-smooth muscle actin (α-SMA) were also tested by real-time reverse transcription PCR and western blot analysis. To elucidate the underlying mechanisms, expression of miR-21 was examined in mTECs treated with TFs using miR-21 mimics transfected into mTECs before TGF-β1 and TFs treatment. Regulation of mothers against decapentaplegic homolog (Smad) signaling by miR-21 was subsequently validated via overexpression and deletion of miR-21 followed by a luciferase assay. RESULTS: TFs treatment attenuated renal fibrosis, and inhibited expression of collagens and α-SMA in the kidneys of mice subjected to UUO. In vitro, the TFs significantly decreased expression of fibrotic markers in TGF-β1-treated mTECs. Moreover, TFs reduced miR-21 expression in a time- and dose-dependent manner in mTECs, increased expression of Smad7, and decreased phosphorylation of Smad3. Treatment with miR-21 mimics abolished the anti-fibrotic effects of the TFs on the TGF-β1-treated mTECs. In addition, genetic deletion of miR-21 upregulated expression of Smad7 and suppressed phosphorylation of Smad3, attenuating renal fibrosis in mice. Bioinformatics predictions revealed the potential binding site of miR-21 in the 3'-untranslated region of Smad7, and this was further confirmed by the luciferase assay. CONCLUSION: TFs ameliorate renal fibrosis via a miR-21/Smad7 signaling pathway, indicating a potential therapy for the prevention of renal fibrosis.