Changes of the Concentration of Short-Chain Fatty Acids in the Intestines of Mice with Different Types of Obesity.

We studied the production of short-chain fatty acids (SCFA) by the intestinal microbiota in mice with obesity caused by a diet and a genetic defect in the leptin receptor gene. In mice, intestinal contents were examined and SCFA were quantitatively assayed by gas chromatography. SCFA concentration in the intestinal contents of mice with alimentary obesity model was significantly lower in the first phase of the experiment (day 14), and the change in their production in dynamics was fundamentally different from this process in the control group (standard diet). The dynamics of the concentration of these metabolites in the model of genetic obesity was similar to that in the control, but the production of SCFA was significantly reduced in mice with leptin resistance in the middle phase (day 60) of the experiment. These findings indicate that the production of SCFA is more influenced by the diet than by leptin resistance.

Markers of dysbiosis in patients with ulcerative colitis and Crohn's disease.

AIM: The aim of the study was to study the taxonomic and functional composition of the gut microbiota in ulcerative colitis (UC) and Crohn's disease (CD) patients to identify key markers of dysbiosis in IBD. MATERIALS AND METHODS: Fecal samples obtained from 95 IBD patients (78 UC and 17 CD) as well as 96 healthy volunteers were used for whole-genome sequencing carried out on the SOLiD 5500 W platform. Taxonomic profiling was performed by aligning the reeds, not maped on hg19, on MetaPhlAn2 reference database. Reeds were mapped using the HUNAnN2 algorithm to the ChocoPhlAn database to assess the representation of microbial metabolic pathways. Short-chain fatty acids (SCFA) level were measured in fecal samples by gas-liquid chromatographic analysis. RESULTS: Changes in IBD patients gut microbiota were characterized by an increase in the representation of Proteobacteria and Bacteroidetes phyla bacteria and decrease in the number of Firmicutes phylum bacteria and Euryarchaeota phylum archaea; a decrease in the alpha-diversity index, relative representation of butyrate-producing, hydrogen-utilizing bacteria, and Methanobrevibacter smithii; increase in the relative representation of Ruminococcus gnavus in UC and CD patients and Akkermansia muciniphila in CD patients. Reduction of Butyryl-CoA: acetate CoA transferase gene relative representation in CD patients, decrease of absolute content of SCFA total number as well as particular SCFAs and main SCFAs ratio in IBD patients may indicate inhibition of functional activity and number of anaerobic microflora and/or an change in SCFA utilization by colonocytes. CONCLUSION: the revealed changes can be considered as typical signs of dysbiosis in IBD patients and can be used as potential targets for IBD patients personalized treatment development.

[MOLECULAR-GENETIC ANALYSIS OF MICROORGANISMS WITH INTRAEPITHELIAL INVASION ISOLATED FROM PATIENTS WITH COLORECTAL CANCER].

The facultative aerobic bacteria isolated from the mucosa of rectum in patients with colorectal cancer in the zone of malignant tumor and neighboring normal mucosa was studied using molecular-genetic methods. The species attribution of bacteria was implemented using the cultural-morphological analysis and sequencing of the 16S rRNA locus. The microorganisms with the intraepithelial invasion to rectal mucosa isolated were identified as representatives of the adherent-invasive (AIEC) subgroup of Escherichia coli and species Klebsiella pneumonia. The molecular analysis by genetic determinants controlling adhesive, hemolytic, and toxigenic activity revealed that some bacterial isolates were able to produce toxins with potential cancerogenic activity (e.g., colibactin and cytotoxic necrotic factor I). Certain bacterial species isolated from malignant and normal rectum epithelium of the same patient demonstrated no difference between analyzed factors of toxigenicity.