Mucosa-attached bacterial community in Crohn’s Disease correlates with the Clinical Disease Activity Index. IBD

In Inflammatory Bowel Diseases (IBD), microbial communities often become imbalanced suggesting abnormal microbial-gut interactions. In this study, we analysed the mucosa-attached gut microbiota from 26 Crohn’s Disease (CD) and seven Ulcerative Colitis (UC) patients and performed 16S rRNA gene amplicon sequencing. The samples were stratified according to their disease activity (CD – Crohn’s Disease Activity Index, CDAI; UC – Mayo Score), treatment by a tumour necrosis factor -α (TNF-α) blocking substance, the mucosal inflammation status and the presence of mutations in the nucleotide-binding oligomerization domain-containing protein 2 (NOD2) gene in the CD group. Statistical analysis showed a strong correlation between the mucosa-attached microbial communities and the CDAI. The mucosa-attached microbiota of patients with a high CDAI was typically enriched by Pelobacter whereas the microbiota of patients in remission and low CDAI was dominated by Bacteroides. Bacterial communities also correlated also with the use of a TNF-α inhibitor and the mucosal inflammation status of the tissue. In CD and UC, there were no significant differences in the bacterial diversity in the different groups. As a summary, a higher CDAI is reflected in changes of the mucosa-attached microbiota and therefore normalizing the microbial composition of patients could potentially result in a reduction of disease activity in CD.