Interferon-¦Ã In The Role Of Transforming Growth Factor-¦Â1-induced Transdifferentiation Of Renal Tubular Epithelial Cells And Connective Tissue Growth Factor Expression

Background: Tubulointerstitial fibrosis is a morphologic hallmark of chronic renal disease and is thought to be the final common pathway leading to end-stage renal disease. It is shown that the rate of the decline of the glomerular filtration rate (GFR) correlates strongly with the extent of tubulointerstitial injury, and tubular epithelial-myofibroblast transdifferentiation (TEMT ) may play an important role in the pathogenesis of renal interstitial fibrosis, so it may be another way to block fibrosis. The observations that interferon-γ inhibits cell proliferation and collagen synthesis of varity of cell types have suggested that intereferon-γ may be useful in the treatment of fibroproliferative diseases. In this study, we examed the capacity of interferon-y to inhibit the transdifferentiation of tubular epitheliar cells to the myofibroblastic phenotype and hence reduce the production of collgen.METHODS: Cultured NRK52E cells were divided into control group, TGF-β1 treated group , IFN-γ treated along with 1000U/ml, TGF-β1 and IFN-γ with different doses treated group. The morphology of transdifferentiate tubular cells was observed under phase-contrast microscopy and scanning electron microscopy. The expression of the mesenchymal marker a-smooth muscle actin, and connective tissue growth factor were shown by immunocytochemistry. Flowcytometry was used to assess the percentage of α — SMA~+ cells and mean channel fluorescence(MCF). The expression of a-SMAmRNA, and CTGFmRNA were examined by RT-PCR. The level of collgen Ⅲ in the culturesupernatant was measured by ELISA.RESULTS: ?TGF-pl caused transdifferentiation of NRK52E cells into myofibroblast-like cells and showed strong a-SMA immunostaining. The percentage of a—SMA+ cells and MCF were more than that of normal control group(P <0.05). The level of collgen III in the culture supernatant was also increased(P <0.05). ?There was no difference between IFN-y treated alone and the control(P >0.05). ?With the presence of TGF-pi and different doses of IFN-y, the NRK52E cells morphology transdifferentiation were inhibited. And with dose increased of IFN-y, there are decrease trend of the percentage of a—SMA+ cells, the amount of collgenlll and the the expression of a-SMAmRNA, and CTGFmRNA(P <0.05).CONCLUSIONS: TGF-pl could induced TEMT and increased the level of collgen III in culture supernatant. IFN-y blocked TEMT. It could also reduce the level of collgen III in the culture supernatant . It maybe indicates that IFN-y inhibits TEMT by the action of reducing the expression ofCTGF.