Salvianolic acid B protects against pulmonary fibrosis by attenuating stimulating protein 1‐mediated macrophage and alveolar type 2 cell senescence

Abstract Idiopathic pulmonary fibrosis (IPF), as the most common idiopathic interstitial pneumonia, is caused by a complex interaction of pathological mechanisms. Interestingly, IPF frequently occurs in the middle‐aged and elderly populations but rarely affects young people. Salvianolic acid B (SAB) exerts antioxidant, antiinflammatory, and antifibrotic bioactivities and is considered a promising drug for pulmonary disease treatment. However, the pharmacological effects and mechanisms of SAB on cellular senescence of lung cells and IPF development remain unclear. We used bleomycin (BLM)‐induced pulmonary fibrosis mice and different lung cells to investigate the antisenescence impact of SAB and explain its underlying mechanism by network pharmacology and the Human Protein Atlas database. Here, we found that SAB significantly prevented pulmonary fibrosis and cellular senescence in mice, and reversed the senescence trend and typical senescence‐associated secretory phenotype (SASP) factors released from lung macrophages and alveolar type II (AT2) epithelial cells, which further reduced lung fibroblasts activation. Additionally, SAB alleviated the epithelial–mesenchymal transition process of AT2 cells induced by transforming growth factor beta. By predicting potential targets of SAB that were then confirmed by chromatin immunoprecipitation‐qPCR technology, we determined that SAB directly hampered the binding of transcription factor stimulating protein 1 to the promoters of SASPs (P21 and P16), thus halting lung cell senescence. We demonstrated that SAB reduced BLM‐induced AT2 and macrophage senescence, and the subsequent release of SASP factors that activated lung fibroblasts, thereby dual‐relieving IPF. This study provides a new scientific foundation and perspective for pulmonary fibrosis therapy.