Bacterial Mucosa-associated Microbiome in Inflamed and Proximal Noninflamed Ileum of Patients With Crohn’s Disease

Abstract

Background Microbiota is most likely essential in the pathogenesis of Crohn’s disease (CD). Fecal diversion after ileocecal resection (ICR) protects against CD recurrence, whereas infusion of fecal content triggers inflammation. After ICR, the majority of patients experience endoscopic recurrence in the neoterminal ileum, and the ileal microbiome is of particular interest. We have assessed the mucosa-associated microbiome in the inflamed and noninflamed ileum in patients with CD. Methods Mucosa-associated microbiome was assessed by 16S rRNA sequencing of biopsies sampled 5 and 15 cm orally of the ileocecal valve or ileocolic anastomosis. Results Fifty-one CD patients and forty healthy controls (HCs) were included in the study. Twenty CD patients had terminal ileitis, with endoscopic inflammation at 5 cm, normal mucosa at 15 cm, and no history of upper CD involvement. Crohn’s disease patients (n = 51) had lower alpha diversity and separated clearly from HC on beta diversity plots. Twenty-three bacterial taxa were differentially represented in CD patients vs HC; among these, Tyzzerella 4 was profoundly overrepresented in CD. The microbiome in the inflamed and proximal noninflamed ileal mucosa did not differ according to alpha diversity or beta diversity. Additionally, no bacterial taxa were differentially represented. Conclusions The microbiome is similar in the inflamed and proximal noninflamed ileal mucosa within the same patients. Our results support the concept of CD-specific microbiota alterations and demonstrate that neither ileal sublocation nor endoscopic inflammation influence the mucosa-associated microbiome.

Landscapes and bacterial signatures of mucosa-associated intestinal microbiota in Chilean and Spanish patients with inflammatory bowel disease

“…3). Previous studies have also shown the same alteration in the abundance of these phyla in the mucosa-associated microbiota of IBD patients [30,58,59]. Moreover, differences between the UC2 and CD2 groups were only observed at the family level, with a decreased abundance of Fusobacteriaceae and Veillonellaceae in the UC2 group (Fig.…”

Butyrate and the Fine-Tuning of Colonic Homeostasis: Implication for Inflammatory Bowel Diseases

“…Of note, the butyrate-producing bacteria Faecalibacterium prausnitzii , Ruminococcus torques , Roseburia inulinivorans , Blautia faecis , and Clostridium lavalense are less abundant [ 21 , 22 , 23 , 24 ] and consequently, luminal butyrate concentrations are lower [ 25 ] and levels of C-reactive protein are higher, reflecting a strong inflammatory status [ 22 ]. Similar changes including a high abundance of E. coli were observed in the mucosa-associated microbiota of CD patients, without differences between the inflamed and non-inflamed area [ 26 , 27 ]. Of interest, adherent-invasive E. coli strains were observed in more than 30% of these patients, being capable of invading the epithelium and replicating in epithelial cells and macrophages, and generating an inflammatory response characterized by an exacerbated IL1β release through NLRP3-inflammasome activation [ 28 , 29 ].…”

Systematic Review: The Gut Microbiome and Its Potential Clinical Application in Inflammatory Bowel Disease

“…Some studies showed that the genus Bifidobacterium is significantly decreased in stool samples during the active phase of CD and UC compared to the remission phase [ 43 , 49 , 68 ]. On the contrary, biopsies showed a higher abundance of Bifidobacterium during active UC, and the proportion of Bifidobacterium was significantly higher in biopsies than in the fecal samples in active CD patients [ 60 ].…”