EGFR对博莱霉素诱导小鼠肺纤维化中上皮-间质转分化的影响

The Effects of EGFR on Epithelial to Mesenchymal Transition in Bleomycin Induced Pulmonary Fibrosis in Mice

目的:探讨表皮生长因子受体(EGFR)在肺内的表达对博莱霉素(BLM)诱导小鼠肺纤维化中上皮-间质转分化的影响。方法:将40只4～6周龄C57BLB/c雄性小鼠随机分为正常对照组(气管滴入PBS),纤维化组(气管滴入BLM 3 mg/kg),EGFRRNAi组(气管滴入BLM 3 mg/kg+气管滴入siRNA 20μl)和RNAi阴性对照组(气管滴入BLM 3 mg/kg+气管滴入siRNA阴性对照20μl)。实验第10天处死小鼠,收获肺组织,检测羟脯氨酸含量;采用逆转录-聚合酶链反应(RT-PCR)法检测EGFR和α平滑肌肌动蛋白(α-SMA)mRNA的表达;肺组织切片行HE染色观察肺组织病理改变,免疫组化染色检测EGFR和α-SMA表达。结果:纤维化组EGFR和α-SMA两者的mRNA和蛋白表达均较正常对照组显著增加;RNAi组肺病理损伤较纤维化组减轻,气道上皮下胶原沉积及肺羟脯氨酸含量减少(P<0.05),肺组织EGFR和α-SMA两者的mRNA和蛋白表达均较纤维化组显著下降(P<0.05)。结论:在博来霉素诱导的肺纤维化中EGFR RNAi抑制EGFR活化,下调α-SMA的表达,减轻了博莱霉素诱导的肺纤维化病理改变。其抑制肺纤维化病理过程可能与其抑制上皮-间质转分化(EMT)有关。

Objective： To investigate the effect of epidermal growth factor receptor（EGFR） expression on epithelial to mesenchymal transition（EMT）in bleomycin induced pulmonary fibrosis in mice.Methods： Forty 4～6 week aged C57BL/c male mice were randomly divided into control group,bleomycin group,bleomycin plus EGFR RNAi groups and RNAi negative control group.Bleomycin group were treated with bleomycin（3 mg/ kg） by injection on day 0,control group were treated with PBS.And bleomycin plus EGFR RNAi group were received EGRF siRNA plus bleomycin intratracheal administration.RNAi negative control group were received negative EGRF siRNA plus bleomycin intratracheal administration.Mice were sacrificed 10 days after the treatments.Hydroxyproline（HYP） assay was performed in the lung tissue.And α-SMA and EGFR mRNA expression were detected by reverse transcriptase-polymerase chain reaction（RT-PCR） technique1.The lung tissue slides were examined pathologically with HE staining,and immunohistochemistry were performed to identify the protein level of EGFR and α-SMA.Results： The mRNA and protein expression of EGFR and α-SMA in BLM group were significantly increased as compared with control group.Histological examination of lung specimens demonstrated that EGFR siRNA administration lessened lung fibrosis induced by bleomycin and significantly reduced HYP content（P〈 0.05） and lung collagen accumulation.The both EGFR and α-SMA mRNA and protein expression in siRNA-treated mice was significantly lessen compared with BLM group（P〈 0.05）.Conclusions： EGFR RNAi lessened the BLM-induced lung fibrosis by inhabiting EGFR expression and this process also downregulated the expression of α-SMA.The inhibition of pulmonary fibrosis may be related to lighten the process of EMT.