The Role And Mechanism Of Tumor Necrosis Factor-? In The Formation Of Chronic Transplanted Renal Interstitial Fibrosis

Objective:To explore the role and mechanism of tumor necrosis factor-a(TNF-a)in the formation of chronic transplanted renal interstitial fibrosis and to study Smurf2 expression change and role played in this process.Methods:We collected 26 cases of normal renal tissues and 26 cases of renal allograft specimens from chronic allograft dysfunction patients to observe the degree of renal interstitial fibrosis by Periodic Acid-Schiff(PAS)staining and Masson staining.Using immunohistochemical staining to detect the expression and distribution of E-cadherin??-smooth muscle actin(a-SMA)?FN and TNF-?,Smad ubiquitination regulatory factor 2(Smurf2).Furthermore,The HK-2 cells were stimulated with TNF-? with a dose-dependent manner or time-dependent manner.Then,we collected the cells to analysis the expression changes of Smurf2,E-cad,?-SMA via western blot assay.Results:Compared with normal group,the degree of renal interstitial fibrosis in CAD group was aggravated according to the results of PAS and Masson staining(P<0.01).Immunohistochemical staining results show that the positive expression of E-cadherin reduced while the positive expression of ?-SMA?FN?TNF-? and Smurf2 increased greatly in CAD group compared with normal group(P<0.01).The results of western blot and qRT-PCR also show that after treatment with TNF-?,the expression of E-cadherin was down-regulated while the expression of ?-SMA?FN and smurf2 were up-regulated in HK-2 cells with a dose-dependent manner or time-dependent manner(P<0.05).Furthermore,the ability of HK-2 cells' migration was also enhanced by TNF-a.Overexpression of Smurf2 could promote TNF-?-induced EMT,whereas knockdown of Smurf2 expression reversed TNF-?-induced EMT.Conclusion:TNF-? may promote the formation of allograft renal interstitial fibrosis via transdifferentiation of human tubular epithelial cells to mesenchymal cells by up-regulating the expression of Smurf2.