Characterization of Adherent Bacteroidales from Intestinal Biopsies of Children and Young Adults with Inflammatory Bowel Disease

Abstract

There is extensive evidence implicating the intestinal microbiota in inflammatory bowel disease [IBD], but no microbial agent has been identified as a sole causative agent. Bacteroidales are numerically dominant intestinal organisms that associate with the mucosal surface and have properties that both positively and negatively affect the host. To determine precise numbers and species of Bacteroidales adherent to the mucosal surface in IBD patients, we performed a comprehensive culture based analysis of intestinal biopsies from pediatric Crohn's disease [CD], ulcerative colitis [UC], and control subjects. We obtained biopsies from 94 patients and used multiplex PCR or 16S rDNA sequencing of Bacteroidales isolates for species identification. Eighteen different Bacteroidales species were identified in the study group, with up to ten different species per biopsy, a number higher than demonstrated using 16S rRNA gene sequencing methods. Species diversity was decreased in IBD compared to controls and with increasingly inflamed tissue. There were significant differences in predominant Bacteroidales species between biopsies from the three groups and from inflamed and uninflamed sites. Parabacteroides distasonis significantly decreased in inflamed tissue. All 373 Bacteroidales isolates collected in this study grew with mucin as the only utilizable carbon source suggesting this is a non-pathogenic feature of this bacterial order. Bacteroides fragilis isolates with the enterotoxin gene [bft], previously associated with flares of colitis, were not found more often at inflamed colonic sites or within IBD subjects. B. fragilis isolates with the ability to synthesize the immunomodulatory polysaccharide A [PSA], previously shown to be protective in murine models of colitis, were not detected more often from healthy versus inflamed tissue.

Linking the Human Gut Microbiome to Inflammatory Cytokine Production Capacity

“…Further, P. distasonis was negatively associated with TNFα and IL-1β in response to C. albicans hyphae stimulation (Figure 3B). In human biopsies, P. distasonis was significantly more abundant in uninflamed versus inflamed tissue (Zitomersky et al, 2013). Consistent with this observation, oral administration of P. distasonis antigens attenuates intestinal inflammation during colitis in mice (Kverka et al, 2011).…”

Gut microbiota, metabolome and immune signatures in patients with uncomplicated diverticular disease

“…These changes included a lower abundance of Bacteroides / Prevotella group and a higher abundance of Enterobacteriaceae. Bacteroides / Prevotella is a subgroup of the phylum Bacteroidetes, which are dominant bacteria associated with the mucosal surface, and can positively or negatively affect the host, depending on the species 26. Several Bacteroides / Prevotella possess the ability to degrade host mucus and their increased abundance has been reported in IBD 27.…”

Vitamin D administration leads to a shift of the intestinal bacterial composition in Crohn's disease patients, but not in healthy controls

“…31 Other studies have proposed an important role for Parabacteroides in the pathogenesis of intestinal inflammation and found a decrease in Parabacteroides at inflamed compared to non-inflamed sites of the intestine. 56,57 Additionally, oral administration of Parabacteroides distasonis led to decreased severity in a murine model of DSS colitis. 58 Interestingly, in our analysis the abundance of Parabacteroides decreased in the first 2 weeks.…”