Results of a longitudinal study demonstrated that decreased diversity of gut microbiota composition and certain microbes are associated with the later clinical course of relapse events and treatment response in ulcerative colitis (UC), according to a study published in Scientific Reports.

During clinical practice, it is imperative to evaluate the risk of relapse and to predict long-term treatment responses in patients with UC. However, it remains unclear how gut microbiota influence disease progression in these patients. Researchers from the Kyushu University in Japan conducted a study to determine whether gut microbiota are associated with relapse and treatment response in patients with UC.   

Between 2012 and 2017, 51 patients with UC were enrolled in the study, with follow-up continuing through 2020. At enrollment, colon mucosal biopsies were obtained and 16S ribosomal RNA sequencing was performed utilizing extracted RNA. Among the 51 patients, 24 were in remission and 27 had active UC upon enrollment.

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The researchers found that of the 24 patients in remission, 17 stayed in remission and 7 developed relapse during the follow-up period. The 7 patients with relapse had lower α-diversity, along with a lower proportion of Clostridiales (P =.0043), and a higher proportion of Bacteroides (P =.047) at enrollment vs those without relapse.

According to their treatment response at 6 months, the 27 patients with active UC were classified into response (n=6), refractory (n=13), and nonresponse (n=8) groups. Compared with the response group, the refractory and nonresponse groups had lower α-diversity, along with a lower proportion of Prevotella (refractory group P =.048; nonresponse group P =.043) at enrollment.

This study had multiple limitations. Patients who had taken antibiotics within 3 months prior to biopsies were excluded. Additionally, the effect of colonoscopy preparation on gut microbiota composition could not be evaluated. Further, the clinical prognosis was predicted by a single test derived from a single colon region, and the sample size of the study was relatively small. Finally, the researchers could not examine whether diet, lifestyle, and metabolic diseases had any influence on the composition of gut microbiota.

These results showed that reduced diversity of gut microbiota composition, as well as particular microbes, is associated with the later clinical course of relapse events and treatment response in UC.

“Of greatest clinical importance, we found that the later clinical course of UC can be predicted and treatment strategies can be determined by assessing mucosa-associated gut microbiota,” the study authors wrote.

Disclosure: This research was supported by Japan Society for the Promotion of Science. Please see the original reference for a full list of disclosures.


Nishihara Y, Ogino H, Tanaka M, et al. Mucosa-associated gut microbiota reflects clinical course of ulcerative colitis. Sci Rep. Published online July 2, 2021. doi: 10.1038/s41598-021-92870-0