Single-cell RNA sequencing reveals profibrotic roles of three kinds of cells in pulmonary fibrosis

Pulmonary fibrosis (PF) is a serious chronic pulmonary disease, and lung transplantation is currently the only treatment option that can prolong patient survival. A greater understanding of the transcriptomes of cells related to the pathogenesis of PF can elucidate the impact of different cell types on its occurrence and development. To this end, we performed single cell RNA sequencing (scRNA-seq) to identify key cells and their biological processes in PF. We analyzed the transcriptomes of a total of 36400 cells isolated from the lungs of control and bleomycin-stimulated mice, and observed significant changes in the macrophages, fibroblasts and epithelial cells in the PF model. The macrophages were divided into alveolar macrophages (AMs) and interstitial macrophages (IMs). Based on the anatomical location, the fibroblasts were classified as alveolar fibroblasts, adventitial fibroblasts and peribronchial fibroblasts. Finally, the epithelial cells were divided into the type I alveolar epithelial cells, transitional type II alveolar epithelial cells, and Scgb3a2+ epithelial cells. The subgroups were further classified into key cell clusters to identify the signaling pathways involved in fibrotic progression. Finally, we identified several ligand-receptor complexes that mediate the communication between microphages, fibroblasts and epithelial cells during PF development. Our findings provide new insights into the mechanisms underlying PF, along with potential therapeutic targets. we induced PF in a mouse model using bleomycin (BLM), and performed single-cell RNA sequencing (scRNA-seq) on the single-cell suspensions obtained from the control and fibrotic lungs.In the single-cell sequencing in this paper, the overall model was constructed according to the modeling time gradient (control group, M-14, M-28). After the completion of modeling, three mice were selected from each group, and after each mouse lung tissue was enzymatically digested into individual cells, equal amounts of cells were selected from all three mice in the same group with the same modeling time for mixing, and one sample was prepared. A total of 3 samples were obtained from the control group, M-14, and M-28, and were tested separately.