Uric Acid Induces Epithelial-mesenchymal Transition Of Renal Tubular Epithelial Cells Via TLR4/NF-κB Signaling Pathway

Objective: To investigate the effect of and mechanism of epithelial-mesenchymal transition(EMT)of renal tubular epithelial cells induced by uric acid,and an effective intervention target was provided for preventing and treating EMT of renal tubular epithelial cells.Methods: Renal tubular epithelial HK-2 cells were cultured in vitro and incubated with different concentrations of uric acid for 48 h.The effects of uric acid on the morphology of HK-2 cells were observed and recorded with the aid of inverted microscope.The protein levels of fibronectin,α-smooth muscle actin(α-SMA)and E-cadherin were detected by Western blotting,while the mRNA expression levels of IL-1β,IL-6 and TNF-α were detected by real-time PCR.Immunofluorescence assay was used for detecting the changes of epithelial cell marker cytokeratin and mesenchymal cell marker vimentin.Results: Compared with untreated HK-2 cells,the HK-2 cells were induced into long-spindled shape after treatment of 15 mg/dL uric acid for 48 h,and the intercellular space markedly was increased.The expression levels of marker Fibronectin and α-SMA of mesenchymal was significantly increased.However,the marker E-cadherin of epithelial cell was significantly decreased(P<0.05).The expression levels of IL-1β and TNF-α was enhanced by high dose of uric acid(P<0.05),Il-6 showed an increasing trend,but no statistical significance(this may be related to the dosage and time of uric acid).and induced activation of TLR4/NF-κB signaling pathway in HK-2 cells(P<0.05).The inhibition of TLR4 activation by small interfering RNA can significantly inhibit the increased expression of NF-κB and α-SMA induced by uric acid(P<0.05).PDTC pretreatment can significantly inhibit uric acid at the same time causes of Fibronectin,α-SMA expression increased significantly(P<0.05),immunofluorescence results showed that uric acid group of vimentin expression than the control group significantly increased,and the expression of cytokeratin significantly lower,on thecontrary,vimentin PDTC pretreatment group significantly lower than control group in expression,and a marked increase in the expression of cytokeratin.Conclusion:Hyperuricemia can be induced the EMT in renal tubular epithelial cells by activation of TLR4/NF-κB signaling pathway,and the targeted intervention of NF-κB signaling pathway can inhibit uric acid induced renal interstitial fibrosis significantly.