Lin28B/let-7d环路调控成纤维细胞功能参与肺纤维化发生

Lin28B/let-7d axis contributes to pulmonary fibrosis by affecting mesenchymal phenotypic properties of lung fibroblasts

目的研究Lin28B/let-7d环路诱导肺成纤维细胞增殖、分化的作用及分子机制,为临床肺纤维化的治疗提供新的策略。方法气管注射博来霉素(bleomycin,BLM)造成小鼠肺纤维化模型;血管紧张素Ⅱ(AngⅡ)及转化生长因子(transforming growth factor,TGF)-β1诱导人胚肺成纤维细胞(MRC-5)纤维性变;qRT-PCR检测组织及细胞中Lin28B、collagen 1α1、collagen 3α1变化;Western blot检测Lin28B蛋白表达;MTT、Edu染色和免疫荧光实验分别检测细胞活力、增殖及成纤维细胞向肌成纤维细胞的转变。结果 Lin28B在肺纤维化小鼠和细胞中表达明显升高。Lin28B可诱导MRC-5细胞胶原合成增加,而过表达let-7d则减轻Lin28B的这一作用。进一步研究发现,Lin28B可诱导成纤维细胞增殖,并促进成纤维细胞向肌成纤维细胞转变,这一作用是通过抑制let-7d来实现的。结论 Lin-28B通过抑制let-7d进而促进成纤维细胞增殖、分化,最终增加成纤维细胞胶原合成,诱发肺纤维化的发生,Lin28B可能作为肺纤维化的治疗新靶点。

Aim To examine the role and uderlying mechanisms of Lin28 /let-7d axis in the proliferation of lung fibrobalsts and fibroblasts-into-myfibroblasts tran-sition,and provide novel strategy for the treatment of idiopathic pulmonary fibrosis （IPF）.Methods We induced experimental lung fibrosis in mice by intratra-cheally injection of bleomycin （BLM）.Ang Ⅱ and TGF-β1 were used to induce fibrogenesis in cultured MRC-5 cells;qRT-PCR and Western blot were applied to determine the changes of Lin28B,collagen 1 α1 and collagen 3α1 ;MTT assay,Edu satining and immun-ofluoresence were used to examine the cell viability, proliferation and fibroblasts-into-myofibroblasts transi-tion in MRC-5 cells.Results Lin28B was increased in the lung of mice with experimental lung fibrosis and in MRC-5 cells treated with AngⅡ or TGF-β1 .Moreo-ver,Lin28B enhanced collagen deposition via inhibi-ting expression of let-7d,which maybe contribute to the progression of IPF.In addition,further studies showed that Lin28B promoted proliferation and fibro-blasts-into-myofibroblasts in MRC-5 cells.Conclusion Lin28B /let-7d axis contributes to fibrogenesis via promotes fibroblasts-into-myofibroblasts transition, which may provide novel approaches for lung fibrosis treatment.