P857 Dysbiosis and ecotypes of the salivary microbiome associated with inflammatory bowel diseases and the assistance in diagnosis of diseases using oral bacterial profiles

Abstract

Background: Although involvement of gut microbiota in IBD has been investigated extensively using culture-independent techniques, limited information exists regarding other members of human microbiome that may be relevant to IBD. Since accumulated knowledge has indicated the noteworthy role of oral microbiota in various systemic diseases, here, we hypothesised the existence of dissonant structure, composition and function of oral microbiota and different community types associated with IBD, and explored oral indicators potentially available for predicting the diseases. Methods: We examined the V3-V4 region of 16S rRNA gene of the salivary bacterial DNA from 54 ulcerative colitis (UC), 13 Crohn's disease (CD) and 25 truly healthy individuals using Illumina sequencing platform. We identified distinctive sample clusters driven by disease or health states based on principal coordinate analysis (PCoA) of both OTU profile and KEGG pathways, and figured out that revisited samples after 2-month therapy migrated to the healthy cluster in PCoA in reference to baseline samples, as was expected. (Table presented) Results: Comparisons of taxa abundances showed the enrichment of Streptococcaceae (Streptococcus) and Enterobacteriaceae in UC and Veillonellaceae (Veillonella) in CD, accompanied by the depletion of Lachnospiraceae and [Prevotella] in UC and Haemophilus and Neisseriaceae (Neisseria) in CD, most of which have been demonstrated the same variation tendency in the gut of IBD patients. IBDrelated microorganisms were in relation to changes of white blood cells and contributed to lower proportions of basic metabolisms, but increased biosynthesis and transport of substances facilitating oxidative stress and virulence. Furthermore, within the UC or CD communities, we observed two robust ecotypes, respectively, which were not demographics or severity-specific, suggesting their value of future unearthing and application for precision medicine. Additionally, indicator species analysis of microbial abundance profiles suggested genera indicative of UC and CD, further confirmed by a longitudinal cohort. Conclusions: This study demonstrates evident salivary dysbiosis and different ecotypes in IBD communities and provides an option for identifying the risk population, which not only enhances our understanding of the IBD microbiome apart from the gut, but also offers a clinically useful means to track IBD considering that saliva can be sampled conveniently and non-invasively.