Effects of FK506 on transdifferentiation and NF-κB activity of human tubular cells induced by TGF-β in vitro

Objective:Tubular epithelial-myofibroblast transdifferentiation may be one of the important mechanisms of interstitial fibrosis in progressive renal diseases. The aim of this study is to examine effect of FK506 on transdifferentiation of human tubular epithelial cells induced by TGF-β and its relationship with NF-κB activity changes. Methodology: The human kidney cells (HKC) were cultured for 48 hours in different conditions:① Serum free as control;② Treated with TGF-β (8ng/ml); ③ Treated with FK506 at different concentration (0.1, 1, 10, 50ng/ml); and ④ Treated with FK506 (0.1, 1, 10, 50ng/ml) plus TGF-β (8ng/ml). The expression of vimentin, cytokeratin, E-cadherin, α-SMA and NF-κ B of HKC was assessed with indirect immunofluorescence, and immunohistochemical staining. The concentrations of fibronectin, and type Ⅰ collagen in culture medium supernatant were detected by ELISA. Results:The expression of cytokeratin and E-cadherin was markedly decreased in HKC treated with TGF-β, but not changed in HKC treated with FK506 alone. The expression of α-SMA, vimentin and NF-κB of HKC cultured with TGF-β was much notable than the control, and significantly decreased in HKC cultured with TGF-β plus FK506. Conclusions:FK506 at given concentrations may inhibit tubular epithelial-myofibroblast transdifferentiation, reduce synthesis and secretion of fibronectin and Ⅰ type collagen of HKC induced by TGF-β as well as NF-κB expression of HKC cells under basic or TGF-β induction condition in a dose-dependent manner. The inhibition of FK506 on transdifferentiation of HKC induced by TGF-β may be related to the down-regulation of NF-κB expression, which needs to be studied further.