Objective:To investigate the effect of specific inhibition of transforming growth factor-β1 (TGF-β1) with SB-431542 on the Smad2/3 and integrin-linked kinase (ILK) signaling molecules in tubule interstitial fibrosis(TIF)-induced cyclosporine A(CsA) in mouse.Methods:50 BALB/c mice were randomly divided into 5 groups (10 mice per group):the CsA model group (CMG),the interventional model group (IMG),the solvent control group (SCG),the low-salt control group (LCG),and the normal control group (NCG).The model mouse was established with low-sodium diet and intragastric administration of cyclosporine A,which was dissolved in olive oil at a dose of 60 mg/(kg·d).After 4 weeks,a specific inhibitor of TGF-β1 (SB-431542)was administered intraperitoneally with 10 mg/(kg·2 d) for 10 days (every other days).Mice were sacrificed at day 38.Serum creatinine (Scr) was measured,hydroxyp roline (Hyp)level and morphological changes of renal tissue were analyzed,expression levels of TGF-β1,P-Smad 2/3 and ILK were respectively detected by immunohistochemistry or Western blot,mRNA levels of TGF-β1,Smad 2/3 and ILK were respectively detected real-time polymerase chain reaction (RT-PCR).Results:Compared with three control groups (NCG,LCG and SCG),mice weight was decreased significantly,Scr level was increased significantly in two modeling groups (CMG and IMG) (P<0.01),and these changes in CMG were more obvious than those of IMG (P<0.05).Different levels of tubulointerstitial injury,interstitial infiltration of inflammatory cells and blue collagen staining in two modeling groups were observed,and particularly evident in CMG.TGF-β1,P-Smad2/3 and ILK immunostaining were mainly expressed in tubulointerstitium.The TGF-β1,P-Smad2/3 and ILK mRNA and immunostaining levels in two modeling groups were significantly increased as compared with three control groups (P<0.01),but their levels in IMG were significantly lower than those of CMG (P<0.05).The level of Hyp in renal tissue was positively correlated with Scr,TGF-β1,Smad2/3 and ILK (r=0.860,0.711,0.776,0.676,P<0.01).Conclusion:The activation of the TGF-β1/Smads signaling pathway plays an important role in the development of chronic CsA-induced TIF.The activation of ILK is closely correlated with the development of TIF,and may be used as a downstream factor of TGF-β1/Smads signaling pathway in regulating CsA-induced TIF.