Background: Intestinal barrier injury is pivotal in sepsis deterioration. M1 macrophage-derived exosomes (M1-Exos) promote gut inflammation. We aimed to reveal roles of M1-Exos in sepsis-induced gut barrier injury and underlying mechanisms. Methods: Exosomes from ileum lamina propria macrophages were intraperitoneally injected into healthy mice to evaluate the impacts on intestinal barrier, NLRP3 inflammasome and intestinal epithelial cells (IECs) pyroptosis. LncRNA NEAT1 was detected in mouse lamina propria macrophages and human monocyte-derived macrophages as well as these macrophages-derived exosomes. The functions of NEAT1 were further investigated using gene knockout (KO) mice and in vitro experiments. The potential interaction between NEAT1 and NLRP3 was assessed via RNA pull-down and RNA-binding protein immunoprecipitation (RIP). Results: Ileum lamina propria macrophages from cecal ligation and puncture (CLP) mice expressed M1 biomarkers. Mice M1-Exos (M-M1-Exos) injection caused barrier impairment, NLRP3 inflammasome activation and IECs pyroptosis. NEAT1 highly expressed in both human M1-Exos (H-M1-Exos) and M-M1-Exos. In NEAT1 KO mice, CLP only caused slight barrier impairment and NLRP3 inflammasome activation without IECs pyroptosis, which were again aggravated by supplementary M-M1-Exos injection. In vitro, treating human intestinal epithelial cell (HIEC) with H-M1-Exos caused barrier damage and NLRP3 inflammasome-mediated pyroptosis. These impairments were inapparent when HIEC was exposed to exosomes that lacked NEAT1 . Moreover, exosomal NEAT1 combined with NLRP3 to activate NLRP3 inflammasome. Conclusion: These findings revealed that gut-resident M1 macrophages secreted exosomal NEAT1 to promote IECs pyroptosis via activating NLRP3 inflammasome, which provided a therapeutic target for septic gut barrier injury.
Yang et al. (Thu,) studied this question.