Abstract：
Pulmonary fibrosis is a chronic and progressive lung disorder. The pro-fibrosis factors induced by M2 macrophage phenotype promote the differentiation of fibroblasts into myofibroblasts, which is essential for pulmonary fibrosis. We aimed to explore the role and mechanism of BTB domain and CNC homology 1 (BACH1) in pulmonary fibrosis. BACH1 was knocked down in THP-1 polarized M2 macrophages with or without FOS-like antigen 2 (FOSL2) overexpression, the expression of M2 macrophage markers was detected. Cell viability, migration, invasion and extracellular matrix (ECM) accumulation were estimated by CCK-8, wound healing, transwell, western bot and immunofluorescence staining. Luciferase reporter and chromatin immunoprecipitation assays were used to verify the binding of BACH1 to FOSL2 promotor region. In vivo, a bleomycin (BLM)-induced pulmonary fibrosis mice model was established to evaluate the effect of BACH1 silencing on the histopathological changes, M2 macrophage phenotype and extracellular matrix (ECM) deposition. Expression of proteins was assessed with western blot. Results indicated that BACH1 expression was upregulated in M2 macrophages polarized from THP-1 cells. BACH1 deficiency inhibited the polarization of THP-1 to the M2 macrophage phenotype to promote the transformation of lung fibroblasts into myofibroblasts. Additionally, BACH1 could transcriptionally activate FOSL2 expression in THP-1-derived macrophages to upregulate TGFβ/SMAD signaling in HFL-1 cells. The animal experiments indicated that BACH1 knockdown alleviated BLM-induced pulmonary fibrosis, M2 macrophage polarization and inactivated FOSL2/TGFβ/SMAD signaling in mice lung tissues. Together, this finding suggests BACH1/FOSL2 may be useful therapeutic targets for the treatment of pulmonary fibrosis.
摘要：
肺纤维化是一种慢性进行性肺病。M2型巨噬细胞表型诱导的促纤维化因子促进成纤维细胞向肌成纤维细胞分化,这对肺纤维化至关重要。我们旨在探讨BTB结构域和CNC同源性1（BACH1）在肺纤维化中的作用和机制。在有或没有FOS样抗原2（FOSL2）过表达的THP-1极化的M2巨噬细胞中，BACH1被敲低，检测到M2巨噬细胞标志物的表达。细胞活力，迁移,侵袭和细胞外基质（ECM）积累通过CCK-8，伤口愈合，transwell,westernbot和免疫荧光染色。荧光素酶报告基因和染色质免疫沉淀测定用于验证BACH1与FOSL2启动子区的结合。在体内,建立博来霉素(BLM)诱导的小鼠肺纤维化模型,评价BACH1沉默对小鼠肺组织病理学改变的影响,M2巨噬细胞表型与细胞外基质(ECM)沉积。用蛋白质印迹评估蛋白质的表达。结果表明，从THP-1细胞极化的M2巨噬细胞中BACH1表达上调。BACH1缺乏抑制THP-1向M2巨噬细胞表型的极化，促进肺成纤维细胞向肌成纤维细胞的转化。此外,BACH1可以转录激活THP-1衍生的巨噬细胞中的FOSL2表达，以上调HFL-1细胞中的TGFβ/SMAD信号传导。动物实验表明BACH1敲除减轻BLM诱导的肺纤维化，小鼠肺组织中的M2巨噬细胞极化和灭活的FOSL2/TGFβ/SMAD信号传导。一起,这一发现提示BACH1/FOSL2可能是治疗肺纤维化的有用治疗靶点.
