[Tea polyphenols ameliorates acute lung injury in septic mice by inhibiting NLRP3 inflammasomes]

Objective: To investigate the mechanism of tea polyphenols (TP) for regulating NLRP3 inflammasomes and alleviating acute lung injury in septic mice.

Methods: Sixty C57BL/6 mice were randomly assigned into sham-operated, cecal ligation and puncture (CLP) and CLP +TP treatment groups, and survival of the mice was recorded after modeling in each group. The lung wet/dry weight ratio and myeloperoxidase (MPO) activity were determined, and lung injury of the mice was evaluated using HE staining and acute lung injury score. The expressions of IL-1β, TNF-α, IL-6, NLRP3, caspase-1 p10, ASC, MPO, and caspase-8 in the lung tissue were detected using ELISA, Western blotting, or immunohistochemical staining. MDA and H₂O₂ levels in the lungs were detected to evaluate the level of oxidative stress. Immunofluorescence assay was used to investigate the co-localization of NLRP3 and NOX4.

Results: The postoperative mortality rate at 72 h, lung wet/dry weight ratio, MPO level and acute lung injury scores were significantly lower in CLP+TP group than in CLP group (P < 0.05). Treatment with TP significantly reduced the expressions of NLRP3-related inflammatory factors (P < 0.05) and lowered MDA and H₂O₂ levels in the lung tissue of the septic mice (P < 0.05). Immunofluorescence co-staining showed a lower level of NOX4 and NLRP3 co-localization in CLP+TP group than in CLP group.

Conclusion: TP inhibits NLRP3 inflammasome-associated inflammation to alleviate CLP-induced acute lung injury in mice through a regulatory mechanism that inhibits NOX4 expression and reduces oxidative stress in the lung tissue.