Tetrastigma hemsleyanum Diels et Gilg polysaccharide mitigates macrophage pyroptosis and prevents acute lung injury by regulating NLRP3/Caspase-1/GSDMD signaling pathways

Abstract

Acute lung injury (ALI) manifests as an intense inflammatory disorder marked by heightened macrophage pyroptotic death and uncontrolled cytokine release. Tetrastigma hemsleyanum Diels et Gilg polysaccharide (THP), derived from a traditional Chinese medicinal herb, was evaluated for its therapeutic effects against ALI. Network pharmacology analysis suggested that THP targets macrophage-related inflammatory pathways. In vitro, macrophage pyroptosis was modeled in THP-1 cells treated with lipopolysaccharide (LPS) and nigericin, whereas in vivo, ALI was induced in BALB/c mice using intratracheal LPS. THP treatment significantly alleviated pulmonary and systemic inflammation, evidenced by decreased neutrophil and macrophage infiltration, lower pro-inflammatory cytokine levels in bronchoalveolar lavage fluid (BALF) and serum, and improved lung histopathology. Flow cytometry demonstrated that THP promoted macrophage polarization from M1 to M2. Western blotting, immunohistochemistry, immunofluorescence, and RT-qPCR confirmed the inhibition of NLRP3, caspase-1, and gasdermin D (GSDMD), leading to reduced pyroptotic cytokine release. Electron microscopy showed that THP mitigated mitochondrial damage and pyroptotic morphological changes, whereas FLICA assays confirmed a decrease in pyroptotic cell proportions. Confocal immunofluorescence revealed diminished ASC speck formation. The findings demonstrate THP's possible therapeutic benefits in ALI mice by regulating the NLRP3/caspase-1/GSDMD signaling axis, thereby alleviating inflammation caused by immune responses.

Keywords: Acute lung injury; Macrophage; Polysaccharide; Pyroptosis; Tetrastigma hemsleyanum Diels et Gilg.