Rosmarinic acid alleviates bleomycin-induced pulmonary fibrosis in mice by activating the Rap1 pathway.

The efficiency of rosmarinic acid (RA) in treating bleomycin (BLM)-induced pulmonary fibrosis (PF) was reported, but mechanisms are unclear. RA, from Herba japonica, is used for air-inflammatory and fibrotic diseases like PF. Its anti-inflammatory and anti-fibrotic roles remain unclear. The study evaluated RA’s effectiveness in treating PF and clarified therapeutic mechanisms. A mouse PF model was established with 5U/kg BLM. RA was given daily from Day 3 for 25 days at 20, 40, or 80 mg/kg. Pirfenidone (PFD) at 300 mg/kg was the positive control. RA’s efficacy was assessed using lung PET-CT and evaluations of pulmonary inflammation, function, and fibrosis. And 4D label-free quantitative proteomics analysis was used to explore mechanisms, corroborated by Western blotting, and immunohistochemistry. RA at 40 mg/kg showed comparable efficacy to PFD and was more effective than 20 mg/kg and 80 mg/kg doses in treating BLM-induced PF in mice. Proteomics and KEGG analysis indicated treatment of RA partially restored protein expression and activated the RAP1 signaling pathway, upregulating proteins like FGF1, Kit, Kras, and Src. RA significantly alleviates BLM-induced PF in mice, with the best results at 40 mg/kg, due to RAP1 pathway activation.