Inhibition of bleomycin‐induced pulmonary fibrosis in SD rats by sea cucumber peptides

Abstract BACKGROUND Pulmonary fibrosis (PF) is the terminal manifestation of a type of pulmonary disease, which seriously affects the respiratory function of the body, and with no effective cure for treatment. This study evaluated the effect of sea cucumber peptides (SCP) on bleomycin‐induced SD rat PF. RESULTS SCP can inhibit the PF induced by bleomycin. PF and SCP did not affect the food intake of rats, but PF reduced the body weight of rats, and SCP could improve the weight loss. SCP reduced lung index in PF rats in a dose‐dependent manner. SCP significantly reduced IL‐1 β , IL‐6, TNF‐ α , α ‐SMA and VIM expression levels in lung tissue ( P < 0.05), significantly decreased TGF‐ β 1 expression level in serum ( P < 0.01) and the LSCP group and MSCP group had better inhibitory effects on PF than the HSCP group. Histomorphological results showed that SCP could ameliorate the structural damage of lung tissue, alveolar wall rupture, inflammatory cell infiltration, fibroblast proliferation and deposition of intercellular matrix and collagen fibers caused by PF. The improvement effect of the MSCP group was the most noteworthy in histomorphology. Metabolomics results showed that SCP significantly downregulated catechol, N ‐acetyl‐ l ‐histidine, acetylcarnitine, stearoylcarnitine, d ‐mannose, l ‐threonine, l ‐alanine, glycine, 3‐guanidinopropionic acid, prostaglandin D2 and embelic acid d ‐(−)‐ β ‐hydroxybutyric acid expression levels in lung tissue. CONCLUSION SCP ameliorate bleomycin‐induced SD rat PF. KEGG pathway analysis proved that SCP intervened in PF mainly via the lysosome pathway, with d ‐mannose as the key factor. © 2023 Society of Chemical Industry.