P1226 Determination of oral and gut mucosal microbiome profiles of patients with treatment-naïve ulcerative colitis

Abstract Background The oral microbiome in ulcerative colitis (UC) patients and its role in the pathogenesis of the disease are still poorly understood. Although there are studies investigating the composition of oral microbiome in UC, there are no studies on concomitant analyses of oral and colonic mucosal samples in treatment-naïve patients. In this study, the oral and mucosal gut microbiome of UC patients and oral microbiota of healthy individuals (HC) were compared. Methods Sixty patients with newly-diagnosed active (mild-moderate severity) UC patients (n=30) and HC (n=30) were included in the study. Dietary habits were stable in the last three months of participants (checked by dietary recall questionnaires) and co-morbidities affecting microbiota profiles were excluded. Multiple colonic mucosa biopsies were obtained from inflamed areas before treatment in UC group. Simultaneously, subgingival plaque samples were analyzed. All samples were identified through next-generation DNA sequencing analysis, evaluated using bioinformatic tests. Results The potential signature bacterial species associated with UC were determined by examining of both gut and oral microbiomes. According to the Microbiome Lefse analysis, Prevotella copri emerged as the prominent common species in the colonic mucosal and subgingival plaque biopsies of UC group. Oral microbiome comparison between UC and HC patients revealed increased Haemophilus parainfluenza and Corynebacterium durum species and decreased F. prastnutzii and Akkermansia muciniphilia in the UC group (p<0.022). Comparative Boxplot analysis of bacterial abundance and alpha-diversity, as indicated by the Shannon index data, revealed that the HC group exhibited higher bacterial abundance and diversity in subgingival plaque samples than the UC group. We found significant association of Bacteroides vulgatus, Prevotella copri, Bacteroides fragilis, Parabacteroides merdae in both colonic mucosal and subgingival plaque samples (oral microbiome) of UC patients (p<0.044). Conclusion Our study is the first to show the oral and colonic mucosal microbiome relationship in UC. The presence of oral dysbiosis associated with UC in our study supports the hypothesis that UC could be associated not only with gut dysbiosis, as previously observed, but also with an imbalance in the oral microbial communities. Interestingly, we could not detect previously reported species of Streptococcus, Oribacterium, Rothia, Neisseria and Porphyromonas in the oral microbiome samples of the UC group. However, oral and gut microbiome profiles share some common microorganisms such as Prevotella copri and Bacteroides fragilis. Further studies are required for determining the potential role of oral dysbiosis is disease severity.