Lespedeza bicolor root extract ameliorates LPS-induced acute lung injury through p38 MAPK/NF-κB pathway

Acute lung injury (ALI) is a severe inflammatory disorder lacking effective therapeutic options. Lespedeza bicolor, a traditional medicinal plant, and its root extract (LBR) contain bioactive constituents with potential anti-inflammatory properties. This study aimed to evaluate the protective effects and underlying mechanisms of LBR against ALI. Network pharmacology combined with transcriptomic and enrichment analyses was used to identify potential targets and signaling pathways of LBR-derived active compounds. The anti-ALI efficacy of LBR was assessed in LPS-induced RAW264.7 cells and mouse models through histopathological examination, measurement of inflammatory cytokines, and immunohistochemistry. RNA sequencing, western blotting, and immunofluorescence assays were further performed to validate key signaling pathways. A total of 157 overlapping targets between LBR and ALI-associated genes were identified, mainly enriched in inflammatory and immune-related pathways, particularly the MAPK and NF-κB cascades. LBR significantly inhibited LPS-induced pro-inflammatory cytokine expression, phosphorylation of p38 MAPK and p65, and nuclear translocation of NF-κB p65 in vitro. In vivo, LBR improved lung histopathology, reduced inflammatory infiltration, and alleviated pulmonary edema. Mechanistically, LBR suppressed activation of the p38 MAPK/NF-κB axis with comparatively weaker effects on ERK and JNK pathways. In conclusion, LBR protects against LPS-induced ALI by modulating inflammatory responses via inhibition of the p38 MAPK/NF-κB signaling pathway, supporting its potential as a promising multi-target natural therapeutic for ALI.