P861 Short-chain fatty acids as a marker of intestinal dysbiosis in patients with inflammatory bowel diseases

Abstract

Background: Normal intestinal microbiota carries out the metabolic, immune, detoxification, and vitamin synthesising functions; its antimutagenic and anti-carcinogenic role associated with the ability to synthesise short-chain fatty acids (SCFA): acetic, propionic and butyric has been proven as well Methods: The purpose of this study was to assess the main functional groups of microorganisms according to their functional value, as well as to determine the content of butyrate and butyrate-producing bacteria in stool samples of IBD patients. The study included 77 patients with ulcerative colitis (UC) and 17 patients with Crohn's disease (CD), total DNA was isolated from faces samples and sequencing was carried out on the SOLiD 5500 W platform (Life Technologies, Foster City, CA, USA). The results of sequencing of 96 faces biological samples obtained from healthy volunteers were used as the control group. The absolute content of butyric acid in the faces was determined in 54 patients with IBD by gas-liquid chromatography analysis (GLC). Results: An increase in the representation of bacteria involved in the vitamins biosynthesis [Bacteroides spp. (B. thetaiotaomicron, B. vulgatus), Bifidobacterium spp. (B. longum)] in patients with UC (8.90% +/- 9.60%) and CD (8.99% +/- 9.42%), respectively, compared with the control group (2.53% +/- 3.52%) was observed, p < 0.05. Besides, there is a decrease in the representation of butyrate-producing bacteria in patients with UC (17.60% +/- 13.21%) and CD (13.90% +/- 14,90%) compared with the control group (27.10% +/- 15.96%), p < 0.05. While determining the levels of butyric acid in stool samples by GLC, we have reaffirmed its absolute decrease: the average level of butyric acid in patients with UC and CD was lower (0.93 +/- 0.83) mg/g compared with the control group (1.75 +/- 0.85) mg/g. The representation of propionate-producing bacteria was higher in CD patients (25.09% +/- 21.51%) than in patients with UC (14.75% +/- 12.89%) and in the control group (11.27% +/- 9.17%), p < 0.05. The proportion of hydrogen-utilising bacteria was higher in the control group (5.94% +/- 7.57%) compared with CD (0.95 +/- 1.83) and UC (3.60 +/- 6.48) patients, p < 0.05. Conclusions: An absolute decrease of butyric acid and representation of butyrate-producing bacteria were observed in IBD patients , which proves the relationship between the decreased gut levels of butyrate and the occurrence of inflammation and increased permeability of the intestinal wall in IBD patients. Increased number of propionate-producing bacteria could be involved in the pathogenesis of CD as well.