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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.
RESUMO
ObjectiveIopromide can induce injury to HK-2 cells, but its exact mechanism remains poorly understood. This study aimed to explore the influence of iopromide on ROS-NLRP3 inflammasome signaling in HK-2 cells.MethodsHK-2 human renal tubular epithelial cells were divided into six groups: control and iopromide at 37, 74, 111, 148 and 185 mgI/mL. The HK-2 cells in the latter five groups were treated with different concentrations of iopromide for 24 hours. Then the ROS level in the cells was detected by 2′,7′-Dichlorodihydrofluorescein diacetate staining and flow cytometry and the protein expressions of NLRP3, ASC, caspase-1, IL-1β, NF-κB and TNF-α determined by Western blot.ResultsThe ROS level was significantly increased in the HK-2 cells treated with iopromide at 37 mgI/ml (4103.89±98.89), 74 mgI/mL (4450.12±108.90), 111 mgI/mL (5050.85±606.76), 148 mgI/mL (6210.57±145.74) and 185 mgI/ml (7105.13±426.63) as compared with that in the control group (2551.71±84.00) (P<0.05). Western blot showed markedly upregulated expressions of NLRP3, ASC, caspase-1, IL-1β and TNF-α in the HK-2 cells in all the latter five groups in comparison with the control (P<0.05) and an increased level of NF-κB after treated with iopromide at ≥111 mgI/ml (P<0.05).ConclusionIopromide may induce injury to HK-2 cells by activating the ROS-NLRP3 inflammasome signaling pathway.