Buyang Huanwu Decoction Alleviates Bleomycin‐Induced Pulmonary Fibrosis via Wnt/β‐catenin and TGF‐β1/Smad Pathways

ABSTRACT Pulmonary fibrosis (PF) is a chronic, progressive interstitial lung disease. Buyang Huanwu Decoction (BHD) contains PF‐improving compounds; it was separated into supernatant (SN) and precipitation component (PC) via water extraction and ethanol precipitation method to explore their differential PF effects, mechanisms, and screen the most effective fraction. Ultra‐high‐performance liquid chromatography‐mass spectrometry and network pharmacology identified BHD compounds and predicted PF targets. Twelve rats (Control, BHD, PC, and SN groups) were used to detect amygdalin, formononetin, kaempferol, ferulic acid, and paeoniflorin in drug‐containing serum. A rat PF model was established via intratracheal bleomycin (BLM) instillation. Seventy‐two rats were divided into six groups: Control, BLM, BHD, prednisone acetate, SN, and PC. After 21‐day treatment, Hematoxylin and Eosin/Masson staining, alkaline hydrolysis (Hydroxyproline), enzyme‐linked immunosorbent assay (tumor necrosis factor‐α/interleukin‐6), immunofluorescence (alpha‐smooth muscle actin), reverse transcription‐quantitative polymerase chain reaction, and Western Blotting (Wnt/β‐catenin and TGF‐β1/Smad pathways) were used. The SN group exhibited higher serum levels of amygdalin, formononetin, and ferulic acid than the BHD and PC groups, with kaempferol similar to the BHD group. BHD, PC, and SN alleviated BLM‐induced lung inflammation and collagen deposition, reduced Wnt3a, glycogen synthase kinase 3 beta, β‐catenin, and transforming growth factor beta 1 (TGF‐β1) mRNA/protein expression, and decreased the p‐Smad3/Smad3 ratio. BHD and its fractions alleviate PF through dual inhibition of Wnt/β‐catenin and TGF‐β1/Smad pathways, with SN demonstrating the highest overall efficacy.