Project description:Inflammatory bowel disease (IBD) is associated with altered microbiota composition and metabolism, but it is unclear whether these changes precede inflammation or are the result of it since current studies have mainly focused on changes after the onset of disease. We previously showed differences in mucus gut microbiota composition preceded colitis-induced inflammation and stool microbial differences only became apparent at colitis onset. In the present study, we aimed to investigate whether microbial dysbiosis was associated with differences in both predicted microbial gene content and endogenous metabolite profiles. We examined the functional potential of mucus and stool microbial communities in the mdr1a -/- mouse model of colitis and littermate controls using PICRUSt on 16S rRNA sequencing data. Our findings indicate that despite changes in microbial composition, microbial functional pathways were stable before and during the development of mucosal inflammation. LC-MS-based metabolic phenotyping (metabotyping) in urine samples confirmed that metabolite profiles in mdr1a -/- mice were remarkably unaffected by development of intestinal inflammation and there were no differences in previously published metabolic markers of IBD. Metabolic profiles did, however, discriminate the colitis-prone mdr1a -/- genotype from controls. Our results indicate resilience of the metabolic network irrespective of inflammation. Importantly as metabolites differentiated genotype, genotype-differentiating metabolites could potentially predict IBD risk.
Project description:Background and aims: Gene mutations or variants leading to insufficient reactive oxygen species (ROS) production have been associated with inflammatory bowel disease (IBD). In particular, 40-50% of patients with chronic granulomatous disease have IBD (CGD-IBD). CGD is caused by inherited defects in any one of the 5 subunits forming the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase complex 2 (NOX2), leading to severely reduced or absent phagocyte-derived ROS production. While conventional IBD therapies can treat CGD-IBD, their benefits must be weighed against the risk of infection in this immune compromised population. Understanding the impact of NOX2 defects on the composition and function of the intestinal microbiota may lead to the identification of treatments for CGD-IBD. Methods: We evaluated GI symptom and quality of life scores, and clinical biomarkers of local (i.e. fecal occult blood and calprotectin) and systemic (i.e. CBC, CRP, ESR, and albumin) inflammation in a cohort of 79 patients with CGD, 8 mutation carriers and 17 healthy controls followed at the National Institutes of Health (NIH). We profiled the intestinal microbiome by 16S rRNA (V4 region) sequencing and the stool metabolome by mass spectrometry in all fecal samples, and further validated our findings by profiling the stool microbiome in a second cohort of 36 patients with CGD recruited from 11 centers across North-America through the Primary Immune Deficiency Treatment Consortium (PIDTC). Predictive functional profiling of the microbial communities based on 16S rRNA sequencing was also performed. Results: After controlling for significant variables, we show decreased alpha diversity and identified distinct intestinal microbiome and metabolomic profiles in patients with CGD compared to healthy individuals. In particular, we observed enrichment for Erysipelatoclostridium spp., Sellimonas spp. and Lachnoclostridium spp. in stool samples from patients with CGD. Despite differences in alpha and beta diversity in samples from the NIH compared to the PIDTC cohort, there were several bacterial taxa that correlated significantly between both cohorts. We further demonstrate that patients with active IBD and/or a history of IBD have a distinct microbiome and metabolomic profile compared to patients without CGD-IBD and identified bacterial taxa to be evaluated as potential markers of disease severity, as well as targets for future therapeutic interventions. Conclusions: Intestinal microbiome and metabolomic signatures distinguished patients with CGD and CGD-IBD and identified microbial and metabolomic candidates to be further evaluated as potential targets to improve the management of patients with CGD-IBD.