DECIPHERING THE SALIVARY MICROBIOME IN CROHN’S DISEASE PATIENTS WITH DIFFERENT FACTORS CONTRIBUTING TO DYSBIOSIS

Crohn’s Disease (CD) is a chronic Inflammatory Bowel Disease (IBD), common in the UAE. Microbiota is necessary to maintain a balanced gut environment which is essential for good health. Dysbiosis can predispose to many diseases including CD. The oral cavity has the second largest and most diverse microbiota after the gut harboring over 700 species of bacteria. This study aims to investigate the alterations in the salivary microbiome in patients with CD compared to Healthy controls (HC). It also aims to compare CD patients for salivary microbiome complexity and diversity according to different factors that can contribute to dysbiosis, including oral health, IBD drug use, disease duration, activity of the disease and relapse of symptoms. Finally, it aims to find any correlation between the inflammatory biomarkers in CD with their levels in saliva, and any possible link to oral dysbiosis. A total of 80 saliva samples were collected from CD patients and HC (n=40 in each group) seeking healthcare from two hospitals in Abu Dhabi, UAE. Information related to the participants’ oral and general health was recorded. DNA was extracted from saliva and sequenced using Oxford nanopore technology for salivary microbiome profiling. Salivary supernatant was used to measure inflammatory biomarkers including C-reactive protein (CRP) and Calprotectin (CAL) by Enzyme-linked immunosorbent assay (ELISA). Data was analyzed using appropriate bioinformatics and biostatistics tools. Obvious differences in the salivary microbiome of CD were found when compared to HC. Five dominant species were enriched in CD and depleted in HC, namely Veillonella dispar, Megasphaera stantonii, Prevotella jejuni, Dolosigranulum pigrum and Lactobacillus backii. Oral health is confirmed to have paramount significance in the dysbiosis of the oral microbiota since most significant features are cariogenic such as Streptococcus mutans or periopathogenic such as Fusobacterium periodonticum. Loss of op