Fecal microbiota Profiling in Irritable Bowel Syndrome and Inflammatory Bowel Disease Patients with Irritable Bowel Syndrome-Type Symptoms

Abstract

BACKGROUND The intestinal microbiota is thought to be involved in the occurrence of Inflammatory Bowel Disease in remission (IBDR) with Irritable Bowel Syndrome (IBS)-type symptoms, but the specific distinct profile of these bacteria remains unclear. Therefore, the purpose of this research is to investigate this issue by conducting a cross-sectional study. METHODS IBS patients were diagnosed according to Rome Ⅳ criteria, IBD diagnosed according to the criteria of European Crohn & Colitis Organization (ECCO), IBDR patients with IBS-type symptoms were defined according to related IBS-type symptoms meeting the Rome IV criteria in IBDR patients, and were included Crohn’s disease in remission (CDR) and ulcerative colitis in remission (UCR) based on Crohn’s Disease Activity Index (DAI) and Mayo Scoring System respectively. Healthy controls come from the physical examination center and exclude people with underlying diseases. All enrolled subjects were divided into six groups, as followed: Health Control, IBS, CDR with IBS-type symptoms (CDR-IBS+), CDR without IBS-type symptoms (CDR-IBS−), UCR-IBS+ and UCR-IBS−. We collected fresh fecal samples from all subjects and applied 16S rRNA sequencing analysis to detect the structure and diversity of the microbiota among different groups. RESULTS A total of 97 subjects were included in this study, of which 18 were health controls, 34 IBS patients, 25 CDR and 20 UCR. The richness of intestinal microbiota in CDR-IBS−was significantly lower than that in the control and IBS groups based on the analysis of observed species and Chao index (P < 0.05). The observed species index in CDR-IBS+ was significantly higher than CDR-IBS− group (median index: 254.8 vs 203, P = 0.036). No difference was found in Alpha diversity between UCR-IBS+ and UCR-IBS−. At phylum level, there was no significant difference between UC or CD with IBS-type symptoms and those without related symptoms. At genus level, the number of Faecalibacterium in CDR-IBS+ increased significantly while Fusobacterium decreased compared with CDR-IBS−(mean relative abundance of Faecalibacterium: 20.35% vs 5.18%, P < 0.05; Fusobacterium: 1.51% vs 5.2%, P < 0.05). However, compared with UCR-IBS - group, the number of Faecalibacterium in UCR-IBS + group decreased, while the number of Streptococcus increased, but there was no statistical difference in the genus structure. Regardless of the phylum or genus level, the abundance and composition of the microbiota of IBS patients were not distinct from those of healthy people. CONCLUSIONS CD patients in remission with IBS-type symptoms may be related to the increase of Faecalibacterium and decrease of Fusobacterium. UC patients in remission with IBS-type symptoms cannot be explained by changes in the abundance and structure of intestinal microbiota from our across-sectional study.