Cornuside mitigates acute lung injury through suppression of NLRP3 inflammasome-mediated pyroptosis and activation of the Keap1-Nrf2 antioxidant response.

INTRODUCTION: Acute lung injury (ALI) is a life-threatening respiratory disorder characterized by excessive inflammation and oxidative stress, with no specific pharmacological therapy currently available. Cornuside (CNS), a bioactive iridoid glycoside derived from Cornus officinalis (Sieb. et Zucc.), has garnered increasing attention for its bone-protective, neuroprotective, anti-inflammatory, and anti-diabetic properties, yet its effects on ALI remain unclear. METHODS: Male C57BL/6J mice received intratracheal lipopolysaccharide to induce ALI and intragastric CNS (25 or 50 mg/kg) 1 h before and 3 h after LPS. Lung injury was assessed by survival, wet/dry ratio, bronchoalveolar lavage fluid (BALF) protein, histology, and open-field testing. Oxidative stress was evaluated by MPO, MDA, and GSH-PX assays. Keap1-Nrf2 pathway activation was analyzed by Western blot and immunofluorescence of Keap1, Nrf2, GPX4, and NQO1, including Nrf2 nuclear translocation. In vitro, bone-marrow-derived macrophages and J774A.1 cells were used to measure NLRP3 inflammasome activation, caspase-1 cleavage, IL-1β release, and GSDMD-mediated pyroptosis by ELISA, Western blot, confocal imaging, and propidium iodide staining. Lung RNA sequencing identified differentially expressed genes and enriched pathways related to oxidative stress and inflammation. RESULTS: CNS significantly improved survival, reduced pulmonary edema, and alleviated lung inflammation and locomotor deficits in LPS-challenged mice. Transcriptomic analysis revealed downregulation of oxidative stress- and inflammation-related pathways. CNS inhibited NLRP3 inflammasome activation, as shown by decreased caspase-1 cleavage, IL-1β release, GSDMD processing, and ASC speck formation in vivo and in vitro. In parallel, CNS activated the Keap1-Nrf2 pathway, increasing nuclear Nrf2 translocation and the expression of antioxidant proteins (GPX4, NQO1), while reducing oxidative stress markers MPO and MDA. DISCUSSION: These findings demonstrate that CNS protects against LPS-induced ALI by concurrently suppressing NLRP3 inflammasome-mediated pyroptosis and enhancing Keap1-Nrf2 antioxidant signaling. This dual mechanism highlights CNS as a promising natural therapeutic candidate for ALI and related oxidative stress-driven lung diseases.