RESUMO
ObjectiveTo investigate whether phosphodiesterase （PDE） 5 inhibitors sildenafil （SIL） or LW1646 prevented renal interstitial fibrosis induced by unilateral ureteral obstruction （UUO）. MethodsMale C57BL/6 mice were randomly divided into four groups （n =6）， namely the Sham group， 7UUO group， 7UUO+SIL group and 7UUO+LW1646 group. Sildenafil （SIL） or LW1646， or vehicle was administered 1 hour before surgery， and the mice were continuously treated once daily （i. g.， 50 mg/kg） for 7 days. The obstructed kidneys were harvested on day 7. Hematoxylin-eosin （HE） and Masson’s staining was used to examine renal histology. Immunoblotting and RT-qPCR were used to detect the expression levels of protein and mRNA for fibrosis， apoptosis， endoplasmic reticulum （ER） stress， autophagy， and pro-fibrotic factors. Human proximal tubule epithelial cells （HK-2） were treated with TGF-β1 for 48 hours or tunicamycin for 24 hours， respectively， to evaluate whether cyclic guanosine monophosphate （cGMP） or PDE5 inhibitors prevents ER stress and pro-fibrotic responses. ResultsAt the 7th days after UUO， the body weight of the mice showed a significant decrease （P< 0.000 1） compared with that in the sham group. The obstructed kidneys showed a significant tubular dilation and interstitial inflammation. The levels of protein and mRNA expression in apoptosis， ER stress， autophagy-related protein and pro-fibrotic factors were also markedly increased in UUO mice （P <0.05）. In contrast， SIL or LW1646 treatment was associated with attenuated tubular dilation， infiltration of inflammatory cells and collagen content in the obstructed kidney of the mice. The protein and mRNA expression levels of renal TGF-β1 were markedly decreased， and the protein expression levels of apoptosis， endoplasmic reticulum stress， and autophagy markers were also significantly downregulated by PDE5 inhibitors. In HK-2 cells， TGF-β1 induced increased expression levels of fibronectin and BiP， which was at least partially reversed by cGMP， a product of PDE inhibition. Additionally， PDE5 inhibitors were found to modulate aberrant levels of autophagy and apoptosis. ConclusionIn conclusion， PDE5 inhibitors， in particular， LW1646， can alleviate the progression of fibrosis by improving ER stress， apoptosis and autophagy as well as downregulating protein and mRNA expression of TGF-β1.
RESUMO
ObjectiveTo investigate the role of bile acid receptor TGR5 activation in renal fibrosis induced by unilateral ischemia reperfusion injury and contralateral nephrectomy （uIRIx） model. MethodsIn vivo： C57BL/6J mice were randomly divided into Sham group， uIRIx group and uIRIx+ lithcholic acid （LCA） group with 6 mice in each group. Kidney fibrosis was induced by uIRIx model， kidney function was evaluated by blood and urine biochemical indexes， and the degree of kidney injury was evaluated by HE staining. Masson staining and immunohistochemistry were used to evaluate the degree of renal fibrosis， and Western Blotting was used to detect the expression of related index proteins of renal cortical fibrosis. Sham group and uIRIx group were set in TGR5+/+ mice and TGR5-/- mice respectively， with 6 mice in each group. The degree of renal fibrosis in each group was detected by Western Blotting. In vitro： TGF-β1 was administered to induce pro-fibrosis response in human renal tubular epithelial cell line （HK2 cells）， LCA was used for drug intervention， cytoskeleton was labeled with phalloidin-FITC staining and the expression of fibrosis related indicator protein in HK2 cells was detected by Western Blotting. ResultsIn vivo： Compared with the Sham group， plasma creatinine level （P=0.007） and urinary albumin/creatinine ratio （P=0.041） in uIRIx group were significantly increased， renal cortical protein TGR5 expression （P=0.002） was decreased， Fibronectin expression （P=0.020） and COL1A1 expression （P<0.001） were increased. At the same time， the kidney structure was damaged and collagen deposition was aggravated. LCA intervention effectively improved the kidney function and alleviated the degree of kidney injury and fibrosis. TGR5 gene knockout increased uIRIx-induced Fibronectin expression （P<0.001） and COL1A1 expression （P=0.001） compared with TGR5+/+ mice. In vitro： TGF-β1 induced morphological changes of HK2 cells， cytoskeletal depolymerization and recombination， and promoted the up-regulation of fibrosis index protein. LCA effectively inhibited the morphological changes and skeletal depolymerization induced by TGF-β1， and down-regulated the expression of fibrosis related indicator proteins. ConclusionsLCA alleviated renal fibrosis induced by uIRIx model， and knockout of TGR5 gene aggravated uIRIx induced renal fibrosis； In HK2 cells， LCA alleviated fibrogenic reaction induced by TGF-β1. This indicates that activation of TGR5 alleviates renal fibrosis induced by uIRIx.