Alisol B 23-acetate alleviates lipopolysaccharide-induced acute lung injury by targeting ANXA1 to modulate the ANXA1/FPR2-mediated MAPK/NF-κB signaling axis.

BACKGROUND: Acute lung injury (ALI), a common respiratory disease with high morbidity and mortality, poses a serious public health threat. Apart from mechanical ventilation, limited safe and effective clinical therapies are available. Alisol B 23-acetate (AB23-a), one of the principal bioactive components of Rhizoma Alismatis, alleviates diverse inflammatory conditions, yet its role in LPS-induced ALI has not been reported. PURPOSE: This study aimed to explore whether AB23-a alleviates ALI and to identify potential mechanisms contributing to its protective effects. STUDY DESIGN: LPS-induced BEAS-2B cells, RAW264.7 macrophages, mouse lung organoids (MLOs) and an LPS-induced mouse ALI model were used as experimental systems. Cells and animals were treated with gradient AB23-a. Functional tests assessed inflammation and macrophage polarization. FPR2 inhibition and ANXA1 knockout/rescue assays verified target engagement and receptor-dependent downstream signaling. METHODS: qRT-PCR and western blotting detected mRNA and protein levels of inflammatory mediators and key ANXA1/FPR2-mediated MAPK/NF-κB signaling molecules. Immunofluorescence evaluated cellular phenotypes. Surface plasmon resonance (SPR) and cellular thermal shift assay (CETSA) confirmed direct AB23-a-ANXA1 binding. RESULTS: The present study demonstrates that AB23-a alleviates LPS-induced inflammation (e.g., IL-6 fell from 3460.89 ± 150.76 pg/ml to 320.00 ± 106.82 pg/ml in LPS-stimulated RAW264.7 cells), and suppresses M1 macrophage polarization. It reduces CD86⁺ macrophage infiltration in lung tissue and improves mouse respiratory function (lung injury score: 0.98 ± 0.04 down to 0.32 ± 0.12; peak expiratory flow (PEF): 1.97 ± 0.20 ml/s up to 5.48 ± 0.25 ml/s). Mechanistically, SPR assay (KD = 1.8 × 10-5 M) and follow-up assays revealed that AB23-a bound directly to ANXA1 and inhibited excessive activation of the MAPK and NF-κB pathways. CONCLUSION: These findings demonstrate the preventive effects of AB23-a in LPS-induced ALI models and identify ANXA1 as an important functional mediator.