Background: Gastrointestinal microbiota is suggested to play an important role in the pathogenesis of ulcerative colitis (UC). Despite various efforts to identify disease-related alterations of the microbiota (dysbiosis), interindividual variation has made it difficult to determine the correlation of specific bacterium with the disease. We thus investigated paired mucosa-associated microbiota obtained from both inflamed and non-inflamed colonic sites in patients with UC.
Methods: Paired mucosal biopsies of the non-inflamed site (transverse colon) and the inflamed site (rectum) were obtained from 14 patients with active left-sided or proctitis UC. We also obtained paired mucosal biopsies (transverse colon and rectum) from 14 healthy controls. The compositions of microbiota were investigated using 16S rRNA gene (V4 region) sequences on the Illumina MiSeq platform, followed by the data analysis using Qiime and LEfSe software.
Results: In both transverse-colon and rectum, less mucosal microbial diversities were observed in patients with UC when compared to those in healthy controls. Although a principal coordinate analysis revealed that the general profile of the mucosal microbiome in the inflamed site was similar to that in the non-inflamed site, linear discriminant analysis (LDA) effect size (LEfSe) showed significant increase of genus Cloacibacterium and family Tissierellaceae in the inflamed site than in the non-inflamed site. On the other hand, neither the profile nor the abundance of mucosal microbiome was different between the transverse colon and rectum in healthy controls.
Conclusions: Mucosal microbial dysbiosis was observed in both inflamed and non-inflamed sites in patients with UC. Genus Cloacibacterium and family Tissierellaceae might be associated with colonic inflammation in UC.