In the Journals

Inflamed, noninflamed mucosal microbiota differ between patients with Crohn's disease, UC

Researchers found no significant differences in microbiota composition between inflamed and noninflamed mucosa when comparisons were made within groups of patients with Crohn’s disease or ulcerative colitis

However, researchers did observe significant differences in the inflamed and noninflamed mucosa of patients with Crohn’s disease vs. ulcerative colitis.

“This study shows important differences in the bacterial profiles of the mucosal microbiota between participants with CD, UC, or non-[inflammatory bowel disease] controls based on analysis of mucosal tissue using a 16S rDNA amplicon-based analysis,” Charles N. Bernstein, MD, of the IBD Clinical and Research Center at University of Manitoba in Canada, and colleagues wrote.

Charles N. Bernstein

Bernstein and colleagues compared the bacterial communities of different gut compartments in the inflamed and noninflamed mucosa in the gastrointestinal tracts of patients with IBD. They collected 166 biopsy specimens from 15 CD, 21 UC and seven non-IBD participants during colonoscopy. Three to four ileum, cecum, mid-colon, and/or rectum biopsies were collected from each patient.

No significant variations were found in any phyla or genera when inflamed and noninflamed mucosa were compared in the different gut compartments within the group of patients with CD. The same result was found within the group of patients with UC.

However, differences were observed between the inflamed and noninflamed mucosa when patients with CD and UC were compared. Bacteroidetes (P = .002) and Fusobacteria (P < .05) were identified more often at the phylum level in inflamed CD mucosa compared with inflamed UC mucosa; Proteobacteria and Firmicutes (P < .05) were identified more often in the inflamed mucosa of patients with UC.

Between the inflamed CD and UC groups, Faecalibacterium (P ≤ .05), Bacteroides (P = .003), and Pseudomonas (P < 0.001) significantly differed in quantity at the genus level.

Within the noninflamed mucosa of the CD and UC groups, the abundance of 13 genera was significantly different. Compared with the controls without IBD, the noninflamed mucosa in patients with UC was the most different.

“Our study presents a comprehensive analysis of the mucosal gut microbiota in IBD while investigating a possible localized dysbiosis in inflamed or noninflamed mucosa at distinct gut compartments,” the researchers concluded. “Although we conclude that the composition of the mucosal microbiota was not altered by the presence of inflammation, we were able to identify an interesting phenomenon whereby the microbiota of the noninflamed gut in IBD are more diverse than the microbiota of the inflamed gut. We have identified several microbes and suggest their disproportional abundances contribute to gut dysbiosis within the inflamed or noninflamed mucosa.” – by Suzanne Reist

Disclosures: Bernstein reports support in part by the Bingham Chair in Gastroenterology; has consulted for AbbVie Canada, Shire Canada, Takeda Canada, Theradiag, Cubist Pharmaceutical, and Mylan Pharmaceutical; and has received educational grants from AbbVie Canada, Shire Canada, Takeda Canada, and Janssen Canada. Please see the full study for a list of all other researchers’ relevant financial disclosures.

Researchers found no significant differences in microbiota composition between inflamed and noninflamed mucosa when comparisons were made within groups of patients with Crohn’s disease or ulcerative colitis

However, researchers did observe significant differences in the inflamed and noninflamed mucosa of patients with Crohn’s disease vs. ulcerative colitis.

“This study shows important differences in the bacterial profiles of the mucosal microbiota between participants with CD, UC, or non-[inflammatory bowel disease] controls based on analysis of mucosal tissue using a 16S rDNA amplicon-based analysis,” Charles N. Bernstein, MD, of the IBD Clinical and Research Center at University of Manitoba in Canada, and colleagues wrote.

Charles N. Bernstein

Bernstein and colleagues compared the bacterial communities of different gut compartments in the inflamed and noninflamed mucosa in the gastrointestinal tracts of patients with IBD. They collected 166 biopsy specimens from 15 CD, 21 UC and seven non-IBD participants during colonoscopy. Three to four ileum, cecum, mid-colon, and/or rectum biopsies were collected from each patient.

No significant variations were found in any phyla or genera when inflamed and noninflamed mucosa were compared in the different gut compartments within the group of patients with CD. The same result was found within the group of patients with UC.

However, differences were observed between the inflamed and noninflamed mucosa when patients with CD and UC were compared. Bacteroidetes (P = .002) and Fusobacteria (P < .05) were identified more often at the phylum level in inflamed CD mucosa compared with inflamed UC mucosa; Proteobacteria and Firmicutes (P < .05) were identified more often in the inflamed mucosa of patients with UC.

Between the inflamed CD and UC groups, Faecalibacterium (P ≤ .05), Bacteroides (P = .003), and Pseudomonas (P < 0.001) significantly differed in quantity at the genus level.

Within the noninflamed mucosa of the CD and UC groups, the abundance of 13 genera was significantly different. Compared with the controls without IBD, the noninflamed mucosa in patients with UC was the most different.

“Our study presents a comprehensive analysis of the mucosal gut microbiota in IBD while investigating a possible localized dysbiosis in inflamed or noninflamed mucosa at distinct gut compartments,” the researchers concluded. “Although we conclude that the composition of the mucosal microbiota was not altered by the presence of inflammation, we were able to identify an interesting phenomenon whereby the microbiota of the noninflamed gut in IBD are more diverse than the microbiota of the inflamed gut. We have identified several microbes and suggest their disproportional abundances contribute to gut dysbiosis within the inflamed or noninflamed mucosa.” – by Suzanne Reist

Disclosures: Bernstein reports support in part by the Bingham Chair in Gastroenterology; has consulted for AbbVie Canada, Shire Canada, Takeda Canada, Theradiag, Cubist Pharmaceutical, and Mylan Pharmaceutical; and has received educational grants from AbbVie Canada, Shire Canada, Takeda Canada, and Janssen Canada. Please see the full study for a list of all other researchers’ relevant financial disclosures.

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