Gut microbiota dysbiosis ‘unspecific’ to microscopic colitis, shared by diarrheal diseases
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Although a feature in microscopic colitis, gut microbiota dysbiosis was also observed in functional and bile acid diarrhea, indicating fecal microbial changes are not due to the disease itself, researchers noted in BMC Gastroenterology.
Data also suggested that colonic lavage with polyethylene glycol prior to a colonoscopy could impact the gut microbiome and promote clinical remission in patients with microscopic colitis.
“Most microbiota studies in microscopic colitis patients are performed after diagnostic colonoscopy without considering the potential effect of colonic lavage,” Lissette Batista, MD, of the department of gastroenterology at MútuaTerrassa University Hospital in Barcelona, Spain, and colleagues wrote. “Patients may achieve clinical remission after colonoscopy, and it is unknown whether lavage-induced changes play a role.”
The researchers noted that “this is the first study with a design that permits the assessment of gut microbiota in active [microscopic colitis] before diagnostic colonoscopy, thus avoiding changes in the microbiome induced by colonic preparation.”
To evaluate microbial diversity, the microbial dysbiosis index and specific microbial changes in fecal samples obtained before and after diagnostic colonoscopy in patients with active [microscopic colitis], Battista and colleagues analyzed fecal samples from 43 patients with chronic, non-bloody watery diarrhea — 16 of whom were determined to have microscopic colitis vs. 11 with functional diarrhea and 16 with bile acid diarrhea — as well as from 12 healthy controls.
Researchers included patients with functional and bile acid diarrhea, in addition to the healthy controls, to examine whether microscopic colitis caused distinct changes in the fecal biome compared with other forms of diarrhea.
Participants collected fecal samples at home 3 days before polyethylene glycol lavage and 30 days after. Biopsy samples also were collected during the colonoscopy when, macroscopically, the colonic mucosa showed mild erythema or edema.
Batista and colleagues noted clinical remission after colonoscopy in more than half of patients with microscopic colitis (53%) and in nearly one-third of patients without microscopic colitis (32%).
In examining the gut microbiota, researchers noted that patients with microscopic colitis, functional diarrhea and bile acid diarrhea had similarly reduced microbial diversity and, thus, considered fecal microbial changes to be associated with stool form rather than microscopic colitis.
“The results obtained show that the reported changes in alpha and beta-diversity in active [microscopic colitis] are unspecific and are shared by other chronic watery diarrheal diseases, such as functional diarrhea and bile acid diarrhea when compared to healthy controls,” Batista and colleagues wrote.
They added: “A considerable number of [microscopic colitis] patients achieved clinical remission after colonoscopy, but we could not demonstrate related [polyethylene glycol]-induced changes in fecal microbiome. In contrast, diarrhea persisted in most patients with bile acid diarrhea, which was associated with ongoing dysbiosis. Further studies are required to study mucosal adhering bacteria and their interplay with the immune function in [microscopic colitis] patients.”
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