Abstract
The inflammatory bowel diseases, encompassing ulcerative colitis (UC) and Crohn’s disease (CD) are characterized by a relapsing-remitting disease course. Despite achieving remission, approximately one-third of the patients relapse annually and yet the microbiota associated with relapse remains elusive. We hypothesized that distinctions in gut microbial composition among patients in clinical remission could potentially influence the disease course. We aimed to discern a distinctive microbial signature in patients with UC in clinical remission, which could serve as a predictive marker for the sustained clinical remission.
This was a prospective observational cohort study conducted as a collaborative work between Dayanand Medical College and Hospital (DMCH), Ludhiana, and Institute of Microbial Technology (IMTECH), Chandigarh. Adult (≥18 years age) patients with an established diagnosis of mild UC (defined as no previous requirement of immune-modulators or biologics to induce or maintain remission) and in clinical remission, were included between January 2019 and December 2020 and followed for one year. The clinical remission was defined as partial Mayo score <2 for at least 6 months, with endoscopic Mayo score 0 and fecal calprotectin <100 µg/g within 4 weeks of enrolment. Utilizing using 16S rRNA metabarcoding based metagenome analysis, the bacterial composition of the collected stool samples were determined.
During the study period, 34 patients (mean age 41.41±13.89 years, 20 [58.82%] males) meeting the eligibility criteria were included for analysis and followed up for one year. (Figure 1) The majority of the patients (21, 61.76%) had left sided colitis. On follow-up, 14 patients (41.17%) experienced a disease relapse (median time to relapse 6 [3-8.25] months). The phyla Firmicutes, Actinobacteria, Bacteroidetes and Proteobacteria were abundant in both the groups [sustained remission (n=20) and disease relapse (n=14)], but specific phyla were enriched in each cohort, Actinobacteria in remission and Proteobacteria in relapse groups. The genera Escherichia, Klebsiella, Enterobacter, Enterococcus, Streptococcus were enriched in relapse group. Interestingly the genus Clostridium was enriched in relapsed cohort whereas genera like Bifidobacterium, Prevotella, Bacteroides, Alistipes, Faecalibacterium were abundant in the remission cohorts.
There are inter-individual differences in the gut microbiota profile of patients with UC in clinical remission. These microbial differences can serve as determinants of the disease course.
