Effects Of Glucocorticoid On The TGF-?1-induced Pulmonary Fibrosis

Objective: The epithelial-to-mesenchymal transition(EMT)is one of the key mechanisms involved in pulmonary fibrosis.Glucocorticoid,one of the most commonly used anti-inflammatory drugs,inhibits the deposition of extracellular matrix in-dependent of its anti-inflammatory effect.In the study,we assessed the effects of glucocorticoid on TGF-?1-induced pulmonary fibrosis in the human alveolar epithelial cell line(A549).Methods: A549 cells were examined for evidence and optimum concentration of EMT after treatment with TGF-?1.EMT was assessed by: morphology under phase-contrast microscopy;mRNA transcripts for E-cadherin(E-cad),vimentin,a-SMA and Collagen I were analyzed by real-time PCR;The protein expression for E-cad,?-SMA and fibronectin were analyzed by Western blot.Then A549 cells were exposed to different concentrations of dexamethasone(Dex)by stimulation with TGF-?1.Western analysis of cell lysates for expression of epithelial phenotypic markers including E-cad,expression of mesenchymal phenotypic markers including ?-SMA and fibronectin.Results: The data showed that TGF-?1 induced A549 cells with an alveolar epithelial type II cell phenotype to undergo EMT in the concentration as low as 2ng/ml and a time-dependent manner.The process of EMT was accompanied by morphological alteration and expression of the fibroblast phenotypic markers fibronectin and vimentin,concomitant with a downregulation of the epithelial phenotype marker E-cad.Dex could not increased the expression of epithelial phenotypic marker E-cad,and could increase mesenchymal phenotypic marker fibronectin in A549 cells,especially in the low concentration.The high concentration of Dex might reduce the generation of fibronectin in the early stages of EMT.Conclusion: TGF-?1 could induce A549 cells undergo pulmonary fibrosis in the concentration as low as 2ng/ml and a time-dependent manner.However,different concentrations of Dex did not have no significant effects on the TGF-?1-induced pulmonary fibrosis,the low concentrations of Dex could promote the deterioration of pulmonary fibrosis,and high concentration of Dex could reduce the generation of extracellular matrix in the early stages of pulmonary fibrosis.