NLRP3 inflammasome mediates pyroptosis of alveolar macrophages to induce radiation lung injury.

Alveolar macrophages play a crucial role in maintaining lung homeostasis. However, the mechanisms underlying alveolar macrophage pyroptosis and inflammasome activation in radiation-induced lung injury remain unclear. In this study, we employed multicolor flow cytometry and single-cell RNA sequencing to reveal the immune cell and cell death landscape in the tissue microenvironment of radiation-induced lung injury. Additionally, we utilized mass spectrometry, co-immunoprecipitation and Duolink techniques to investigate the core inflammasome responsible for mediating alveolar macrophage pyroptosis. We noticed that the percentage of alveolar macrophages, T, B and epithelial cells decreased significantly post-irradiation. Notably, the proportional changes in alveolar macrophages closely correlated with Szapiels' pneumonia score. Furthermore, alveolar macrophages emerged as the earliest cell type to initiate pyroptosis and act as pivotal regulators of cell communication. In vitro and in vivo experiments, we observed a significant increase in NLRP3 binding to the apoptosis-associated speck-like protein in irradiated alveolar macrophages. In vivo, MCC950 effectively inhibited alveolar macrophage pyroptosis and significantly reducing inflammatory cells recruitment. Subsequently, targeting AM pyroptosis ultimately inhibit the infiltration of interstitial macrophages and the activation of fibroblasts, decrease collagen deposition and alleviate the severity of radiation-induced lung fibrosis. Targeting alveolar macrophage pyroptosis and NLRP3 inflammasome activation hold substantial therapeutic potential for mitigating radiation-induced lung injury.