Department of Molecular Preventive Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan; Japan Agency for Medical Research and Development-CREST Program, Tokyo, Japan.
Department of Molecular Preventive Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan; Division of Molecular Regulation of Inflammatory and Immune Diseases, Research Institute of Biomedical Sciences, Tokyo University of Science, Noda, Japan; Japan Agency for Medical Research and Development-CREST Program, Tokyo, Japan.
Biochem Biophys Res Commun. 2019 Jun 30;514(3):684-690. doi: 10.1016/j.bbrc.2019.05.011. Epub 2019 May 8.
Pulmonary fibrosis is characterized by progressive and irreversible scarring of alveoli, which causes reduction of surface epithelial area and eventually respiratory failure. The precise mechanism of alveolar scarring is poorly understood. In this study, we explored transcriptional signatures of activated fibroblasts in alveolar airspaces by using intratracheal transfer in bleomycin-induced lung fibrosis. Lung fibroblasts transferred into injured alveoli upregulated genes related to translation and metabolism in the first two days, and upregulated genes related to extracellular matrix (ECM) production between day 2 and 7. Upstream analysis of these upregulated genes suggested possible contribution of hypoxia-inducible factors 1a (Hif1a) to fibroblast activation in the first two days, and possible contribution of kruppel-like factor 4 (Klf4) and glioma-associated oncogene (Gli) transcription factors to fibroblast activation in the following profibrotic phase. Fibroblasts purified based on high Acta2 expression after intratracheal transfer were also characterized by ECM production and upstream regulation by Klf4 and Gli proteins. Pharmacological inhibition of Gli proteins by GANT61 in bleomycin-induced lung fibrosis altered the pattern of scarring characterized by dilated airspaces and smaller fibroblast clusters. Activated fibroblasts isolated from GANT61-treated mice showed decreased migration capacity, suggesting that Gli signaling inhibition attenuated fibroblast activation. In conclusion, we revealed transcriptional signatures and possible upstream regulators of activated fibroblasts in injured alveolar airspaces. The altered scar formation by Gli signaling inhibition supports that activated fibroblasts in alveolar airspaces may play a critical role in scar formation.
肺纤维化的特征是肺泡进行性和不可逆转的瘢痕形成，这导致表面上皮面积减少，最终导致呼吸衰竭。肺泡瘢痕形成的确切机制尚不清楚。在这项研究中，我们通过博来霉素诱导的肺纤维化的气管内转移，研究了肺泡气腔中活化成纤维细胞的转录特征。转移到受损肺泡中的肺成纤维细胞在最初的两天内上调了与翻译和代谢相关的基因，在第 2 天至第 7 天之间上调了与细胞外基质（ECM）产生相关的基因。对这些上调基因的上游分析表明，缺氧诱导因子 1a（Hif1a）可能在前两天对成纤维细胞的激活有贡献，而 Kruppel 样因子 4（Klf4）和神经胶质瘤相关癌基因（Gli）转录因子可能在随后的促纤维化阶段对成纤维细胞的激活有贡献。在气管内转移后根据 Acta2 高表达纯化的成纤维细胞也表现出 ECM 产生，并且上游受 Klf4 和 Gli 蛋白调节。在博来霉素诱导的肺纤维化中通过 GANT61 抑制 Gli 蛋白可改变瘢痕形成模式，其特征是肺泡扩张和更小的成纤维细胞簇。从 GANT61 处理的小鼠中分离出的活化成纤维细胞显示出迁移能力降低，表明 Gli 信号抑制减弱了成纤维细胞的激活。总之，我们揭示了受损肺泡气腔中活化成纤维细胞的转录特征和可能的上游调节因子。Gli 信号抑制改变的瘢痕形成支持肺泡气腔中的活化成纤维细胞可能在瘢痕形成中起关键作用。
