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* = Presenting author

P749 Not only butyrate-producing bacteria but possibly also Bacteroides thetaiotaomicron protects against ulcerative colitis

S. Sitkin*1, 2, T. Vakhitov1, E. Tkachenko2, T. Zhigalova2, L. Oreshko2, M. Suvorova3

1State Research Institute of Highly Pure Biopreparations, Department of Microbiology, St Petersburg, Russian Federation, 2North-Western State Medical University named after I.I. Mechnikov, Department of Internal Diseases, St. Petersburg, Russian Federation, 3Institute of Experimental Medicine, St. Petersburg, Russian Federation

Background

Ulcerative colitis (UC) is a chronic autoimmune disease of unclear aetiology. Celiac disease (CD) is a chronic immune-mediated disorder triggered by gluten that appears in genetically predisposed persons and that primarily affects the small intestine. Human gut microbiota contributes to pathogenesis of UC and CD. Features of intestinal dysbiosis in UC and CD need to be clarified to enhance treatment effects.

Methods

Fresh faecal samples were collected from 37 UC patients, 40 CD patients, and 38 healthy controls (HC). The quantitative real-time polymerase chain reaction (qRT-PCR) was used for faecal microbiota assessment. Serum metabolomic profiles were obtained using the GC-MS.

Results

UC patients had lower Faecalibacterium prausnitzii counts compared with HC (p < 0.01) and higher abundance of Lactobacillus group when compared with HC or CD patients (p < 0.01). Butyrate-producing bacteria (primers for Butyryl-CoA: acetate CoA transferase gene were used) were more depleted in UC patients compared with HC (p < 0.05). Surprisingly, Bacteroides thetaiotaomicron was detected less frequently in UC patients than in HC (p = 0.016). The absence of Bacteroides thetaiotaomicron in faeces or its levels below the limit of detection were significantly associated with an increased risk of UC (RR = 2.63; 95% CI 1.14–6.06). CD patients had lower Bifidobacterium spp. counts than HC or UC (p < 0.05). Taxonomic (microbiological) dysbiosis in both UC and CD was characterised by a higher Bacteroides fragilis/Faecalibacterium prausnitzii ratio compared with HC. Changes in serum concentrations of some organic acids of microbial or combined origins indicated the presence of metabolic dysbiosis. Orally administered butyrate plus inulin as supplement to mesalazine in UC or gluten-free diet (GFD) in CD not only improved symptoms, but also normalised gut microbiota composition and serum metabolomic profiles in both disease.

Conclusion

It was shown for the first time that the absence or undetectable counts of Bacteroides thetaiotaomicron in the faeces is associated with increased risk of UC. These data suggest the possibility of using probiotic strains of Bacteroides thetaiotaomicron in patients with UC. Low counts of butyrate-producing bacteria and F. prausnitzii also suggest the desirability of co-treatment with oral butyrate/butyrate-enhancing agents and anti-inflammatory drugs in UC. An increased B. fragilis/F. prausnitzii ratio can serve as available biomarker for intestinal dysbiosis in both UC and CD. Lactic acid bacteria should be used more cautiously as probiotics in UC. Treatment that increases colonic bifidobacteria (eg, prebiotics) can be considered in CD. Oral butyrate plus inulin can be used in both UC and CD for improving symptoms, gut microbiota, and serum metabolome.