Regulation of the gut microbiota and intestinal homeostasis by phagocyte NADPH oxdiase (INC1P.351)

Abstract

Abstract The phagocyte NADPH oxidase generates reactive oxygen species (ROS) for microbial killing, and its impairment gives rise to Chronic Granulomatous Disease (CGD), a primary immunodeficiency characterized by recurrent infections and granulomatous lesions. Mutations in Nox2 (Cybb), a critical subunit of the oxidase, contribute 66% of CGD. In our study, we found spontaneous inflammation in the intestine of naïve Cybb-/- mice, indicated by higher levels of IL-1b, IL-6 and TNFα in lamina propria macrophages, as well as increased levels of IFNγ and IL-17A in CD4+ T cells. In addition, Klebsiella pneumoniae, a bacterium frequently found in granulomatous lesions in CGD patients, were detected in the spleens and mesenteric lymph nodes (MLNs) of naïve Cybb-/- mice, and IP administration of this pathobiont strain of K. pneumonia led to rapid mortality of wild-type mice. Oral administration of this K. pneumoniae induced intestinal inflammation in wild-type and Cybb-/- mice, but translocation of K. pneumoniae to MLNs was drastically enhanced in Cybb-/- mice and bone marrow chimeras with a neutrophil-specific deficiency in NOX2. Thus, our results demonstrate the importance of neutrophil-derived ROS in restricting dissemination of pathobionts from the intestine under steady-state conditions. Therefore, our study underscores a critical role for the NADPH oxidase in regulating intestinal homeostasis and provides insights into intestinal complications in CGD patients.