The ileal mucosa-associated microbiota may help predict recurrence in patients with Crohn’s disease

Recurrence of inflammatory lesions is frequent in patients undergoing ileal resection for Crohn’s disease (CD). Although male gender, active smoking at surgery and previous intestinal resection have all been associated with a higher risk of endoscopic post-operative recurrence—as assessed by ileocolonoscopy—there is not a single clinical risk factor that can be used as a perfect predictor of early postoperative endoscopic recurrence.

A new study, led by researchers from Saint Antoine Hospital, the French National Institute for Agricultural Research and other institutions in France, reveals that ileal mucosa-associated microbiota may help predict recurrence in patients with CD after ileocecal resection.

The researchers analyzed the ileal mucosa-associated microbiota by using 16S sequencing at the time of surgery and/or at the time of postoperative endoscopic evaluation (about 6 to 12 months after surgery) in 201 patients from the REMIND cohort.

The ileal mucosa-associated microbiota exhibited major changes following CD surgery that differed between the time of surgery and the time of postoperative endoscopic evaluation. Specifically, changes included a decrease in beta diversity and a decrease in the Gammaproteobacteria class, an increase in the Alphaproteobacteria class, a decrease in the Bacilli class and an increase in the Clostridiales order.

On the other hand, endoscopic recurrence itself was associated with stronger alterations in gut microbiota composition when compared with patients without endoscopic recurrence. At the time of endoscopic evaluation, patients with endoscopic recurrence showed strong changes in ileal mucosa-associated microbiota that resembled the gut microbiota profile observed in ileal CD, but which underwent specific additional changes within each phylum. Such changes included a reduction in alpha diversity, an increase in Proteobacteria members and a decrease in members belonging to Lachnospiraceae and Ruminococcaceae families, the latter of which is associated with intestinal health.

In contrast, patients without endoscopic recurrence at 6 to 12 months after surgery showed increased levels of bacteria from the Lachnospiraceae and the Ruminococcaceae families, such as the Roseburia, Blautia and Dorea genera.

Finally, at the time of ileal resection certain bacterial taxa were linked to endoscopic recurrence and, thus, are suggested to better predict relapse than usual clinical risk factors. Within the battery of risk factors assessed, the high abundance of bacteria from the Gammaproteobacteria, the Ruminococcus gnavus group and Corynebacterium genera were the most predictive gut microbiota-related features for anticipating endoscopic recurrence.

On the whole, these findings show that ileocecal resection and endoscopic recurrence are associated with changes in ileal mucosa-associated microbiota. The role of gut microbiota at the time of surgery as a predictor of endoscopic recurrence offers a potential means of better adjusting treatment in patients with CD who need a surgical bowel resection.

Reference:

Sokol H, Brot L, Stefanescu C, et al. Prominence of ileal mucosa-associated microbiota to predict postoperative endoscopic recurrence in Crohn’s disease. Gut. 2019. doi: 10.1136/gutjnl-2019-318719.