Effects of Interferon-γ on Tubular Epithelial-myofibroblast Transdifferentiation in vitro

Objective To investigate the effects of interferon-γ(IFN-γ) on tubular epithelial-myofibroblast transdifferentiation(TEMT) induced by transforming growth factor(TGF-β1).Methods The normal rat kidney tubular epithelial cells(NRK52E) were cultured and divided into blank(NRK52E cells only) control group,TGF-β1(3 ng/mL) treated group,IFN-γ(1000 IU/mL) treated group,and IFN-γ inhibition group(TGF-β1 3 ng/mL + IFN-γ 200,400,600,1000,2000,3000 IU/mL).After 72 hours of treatment,the morphology of cells was observed under phase-contrast microscopy and scanning electron microscopy.The expressions of α-smooth muscle actin(α-SMA) and connective tissue growth factor(CTGF) were detected by immunocytochemistry.Flowcytometry was employed to measure the percentage of α-SMA+ cells and the mean channel fluorescence(MCF).The expressions of α-SMA mRNA and CTGF mRNA were examined by reverse transcription-polymerase chain reaction analyses(RT-PCR).The level of collagen Ⅲ in the culture supernatant was measured by Enzyme-linked immunoadsordent assay(ELISA).Results NRK52E cells cultured in the control group showed a classic cobblestone morphology.TGF-β1 induced NRK52E cells to transdifferentiate into myofibroblast-like cells,which showed strong α-SMA immunostaining.The TGF-β1 treated cells had higher percentage of α-SMA+ cells,MCF and α-SMA mRNA,increased CTGF mRNA expression,and ascended collagen Ⅲ than the blank controls(P0.05).IFN-γ treated alone did not make any changes to the cell morphology,the expressions of α-SMA mRNA and CTGF mRNA and the level of collagen Ⅲ(P0.05).IFN-γ exerted a strong inhibitory effect on the TEMT induced by TGF-β1.With the increase of IFN-γ,the percentage of α-SMA+ cells,the level of collagen Ⅲ,and the expressions of α-SMA mRNA and CTGF mRNA decreased(P0.05).Conclusion IFN-γ inhibits the TEMT induced by TGF-β1 and reduces the level of collagen Ⅲ.