Genotype-specific immune responses at the intestinal barrier predispose to colitis in mouse models of chronic granulomatous disease

Abstract

Chronic granulomatous disease (CGD) is an inborn error of immunity that is caused by defects in any 1 of the 5 subunits (gp91phox, p47phox, p22phox, p67phox, p40phox) that form the NAD phosphate oxidase complex 2 (NOX2) or in the chaperone protein essential for reactive oxygen species (ROS) that supports its assembly. These defects lead to severely reduced phagocyte-derived ROS production. Almost 50% of patients with CGD have inflammatory bowel disease (IBD) associated with dysbiosis, and the age of IBD onset may vary according to the CGD genotype. Although we previously demonstrated that the intestinal microbiota determines colitis susceptibility in CGD mice, the underlying mechanisms remain unknown. We hypothesized that NOX2 defects are associated with distinct intestinal microbiome signatures and immune responses, which impact colitis severity. Chemical colitis susceptibility was evaluated in 2 strains of CGD mice (gp91phox-/- and p47phox-/-) with distinct microbiotas from 2 different animal facilities, while also evaluating the impact of microbiota standardization and colitogenic microbiota transfer on mucosal immune responses at the intestinal barrier. Although p47phox-/- and gp91phox-/- mice that harbored a colitogenic microbiota had increased colitis severity, the intestinal epithelial cells from p47phox-/- mice produced more ROS, which was associated with increased NOX isoform gene expression. In contrast, gp91phox-/- mice had decreased mucin production and a mucosal immune response profile suggestive of increased inflammasome activation at the intestinal barrier when compared with control and p47phox-/- mice. Our findings suggest that the microbiota impacts colitis susceptibility in a CGD genotype-specific manner, thereby potentially explaining differences in the timing of IBD onset in patients with different CGD genotypes and identifying potential novel and personalized therapeutic targets.