Tauroursodeoxycholic Acid Inhibits Epithelial-Mesenchymal Transition During Bleomycin-Induced Pulmonary Fibrosis

Objective: To investigate the effect of TUDCA on epithelial-mesenchymal transition during bleomycin-induced pulmonary fibrosis.Methods: Adult C57BL/6j mice(8 weeks,24-26 g)were randomly divided into 4 groups.In BLM alone and BLM + TUDCA group,mice were intratracheally injected with a single dose of BLM(3.0 mg/kg).In TUDCA alone and BLM + TUDCA group,mice were intraperitoneally injected with TUDCA(250 mg/kg)once a day.Mice were intraperitoneally injected with NS and administered with NS by intratracheal injection in control group.Mice were sacrificed at 21 d after BLM treatment.The left lung was fixed with 4% paraformaldehyde,embedded in paraffin,and sectioned.The HE staining of slices was used to evaluate inflammatory cell infiltration and alveolar septal destruction.Sirius Red staining was used to evaluate the collagen deposition in the lungs.Immunohistochemistry(IHC)was used to relevant proteins detect in lung tissues.Right lung stored at-80 ? for detection of related proteins and m RNA.Results: As shown by HE staining,BLM-treated mice were inflammatory cell infiltration and alveolar septal destruction.After pretreatment with TUDCA,inflammatory cell infiltration and alveolar septal destruction were significantly improved.Sirius Red staining showed a large amount of collagen deposition in the BLM group.After pretreatment with TUDCA,the collagen deposition was significantly reduced.IHC displayed that the percentage of pulmonary ?-SMA-positive cells was markedly elevated in the BLM-treated mice.Further analysis displayed that pulmonary ?-SMA was elevated by BLM.Correspondingly,pretreatment with TUDCA downregulated ?-SMA in the lungs of BLM-treated mice.By contrast,pulmonary E-cadherin was obviously decreased in BLM-treated mouse lungs.After pretreatment with TUDCA,downregulation of pulmonary E-cadherin level was inhibited.Pulmonary Tgf-?1 m RNA level was upregulated by BLM treatment.After pretreatment with TUDCA,BLM-induced upregulation of pulmonary Tgf-?1 m RNA was inhibited.As shown in IHC,pulmonary pSmad3-positive cells were elevated by BLM treatment.After pretreatment with TUDCA,elevation of p-Smad3-positive cells induced by BLM was significantly attenuated.In addition,the levels of pulmonary p-Smad2/3 was elevated by BLM treatment.After pretreatment with TUDCA,BLM-induced pulmonary p-Smad2/3 elevated was inhibited.As shown by IHC,pulmonary Ki67-positive cells were increased in BLM-treated mice.Of interest,BLM-induced fibroblast proliferation was alleviated in TUDCA-treated mice.As expected,pulmonary PCNA level was increased in BLM-treated mice.After pretreated by TUDCA,BLM-induced elevation of pulmonary PCNA was inhibited.Pulmonary HO-1 and 3-NT protein level was increased after BLM treatment.After pretreatment with TUDCA,BLM-induced increase of 3-NT and HO-1 in mouse lungs was inhibited.IHC showed that 3-NT-positive cells were increased in the BLM-treated mice.After pretreatment with TUDCA,the percentage of pulmonary 3-NT-positive cells was decreased.In the BLM group,GRP78 and was CHOP were elevated in mouse lungs of BLM-treated mice.After pretreatment with TUDCA,the level of GRP78 and CHOP was decreased.Conclusion: TUDCA can inhibit epithelial-mesenchymal transition and pulmonary fibrosis caused by bleomycin.