Abstract
OBJECTIVES: To investigate the effect of amentoflavone (AF) for alleviating lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice and inhibiting NLRP3/ASC/Caspase-1 axis-mediated pyroptosis. METHODS: Female BALB/c mice were randomly divided into control group, LPS group, and AF treatment groups at low, moderate and high doses (n=12). ALI models were established by tracheal LPS instillation, and in AF treatment groups, AF was administered by gavage 30 min before LPS instillation. Six hours after LPS instillation, the mice were euthanized for examining lung tissue histopathological changes, protein levels in BALF, and MPO levels in the lung tissue. In the in vitro experiment, RAW264.7 cells were pretreated with AF, AC (a pyroptosis inhibitor), or their combination for 2 h before stimulation with LPS and ATP. The changes in cell proliferation and viability were detected using CCK-8 assay, and IL-1β, IL-6, IL-18, and TNF-α levels were determined with ELISA. Immunohistochemistry, immunofluorescence assay, and immunoblotting were used to detect the protein levels of NLRP3, ASC, cleaved caspase-1, and GSDMD N in rat lung tissues and the treated cells. RESULTS: In mice with LPS exposure, AF treatment significantly improved lung pathologies and edema, reduced protein levels in BALF and pulmonary MPO level, inhibited the high expression of NLRP3/ASC/Aspase-1 axis, reduced the expression of GSDMD N, and lowered the release of IL-1β, IL-6, IL-18, and TNF‑α. In RAW264.7 cells with LPS and ATP stimulation, AF pretreatment effectively reduced cell death, inhibited activation of the NLRP3/ASC/Aspase-1 axis, and reduced GSDMD N expression and the inflammatory factors. The pyroptosis inhibitor showed a similar effect to AF, and their combination produced more pronounced effects in RAW264.7 cells. CONCLUSIONS: Amentoflavone can alleviate ALI in mice possibly by inhibiting NLRP3/ASC/Caspase-1 axis-mediated cell pyroptosis.