The animal model of intestinal dysbiosis induced by antibiotics was created. Dysbiotic condition was confirmed by the changes in titre of the indigenous microbiota (excessive growth of opportunistic microorganisms and reduced number of lactobacilli, bifidobacteria and enterococci) and the appearance of dyspeptic symptoms. Consumption of the fermented milk product with probiotic strain Enterococcus faecium L5 led to the rapid disappearance of dysbiosis symptoms, normalisation of the microbiota, increase in expression of IL-10 and decrease in IL-8 expression.

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The effect of probiotic Enterococcus faecium strain L-3 was studied in rats with experimental allergic encephalomyelitis (EAE). Glatiramer acetate (GA) was used as control drug. E. faecium strain L-3 and GA both were able to reduce the severity of EAE in a similar fashion. Both approaches increased the proportion of EAE resistant rats and rats with mild disease, prolonged the inductive phase of EAE and reduced the disease duration. Study of the phenotypes of immune cells in blood revealed the differences in immunoregulatory pathways that mediate the protective action of probiotic or GA treatment of EAE. The presence of pronounced protective and immunomodulating effects of the probiotic E. faecium strain L-3 opens an opportunity of its application for the treatment of multiple sclerosis.

Резюме. Исследовано влияние трех штаммов пробиотических бактерий: Lactobacillus rhamnosus K32 (L), Bifidobacterium longum GT15 (B), Enterococcus faecium L-3 (E), на уровни экспрессии и содержания ключевых цитокинов при помощи полимеразной цепной реакции с обратной транскрипцией и иммуноферментного анализа соответственно. В работе использованы культура клеток промоноцитарного происхождения (HTP-1) и экспериментальная модель дисбиоза кишечника. В геномах штаммов В и E ранее были выявлены гены, кодирующие бактериоцины, гены компонентов внешней мембраны, пилей и экзополисахаридов, участвующих в модуляции иммунной системы. При исследовании влияния пробиотических штаммов и их супернатантов на экспрессию цитокинов на культуре клеток выявлено увеличение экспрессии TNFα, обусловленное B, E и супернатантом L. Культура В дополнительно вызывала экспрессию IL-8 и IL-10. При коррекции дисбиоза кишечника у крыс (индуцированного метронидазолом и ампициллином) пробиотиками было показано, что нарушение в составе микробиоты (чрезмерный рост Klebsiella spp., низкое содержание Faecalobacterium prausnitzii) оставались у животных после введения L, как в контроле (без введения пробиотиков). В отличие от этих групп у крыс после введения E и B были выявлены: 1) низкие уровни экспрессии провоспалительных цитокинов (IL-8, TNFα, MCP-1) в брыжеечных лимфатических узлах и содержание данных факторов в сыворотке крови; 2) увеличение содержания в сыворотке крови антивоспалительного цитокина TGF-β. В данной работе, при помощи двух взаимодополняющих моделей, выявлены индивидуальные особенности иммуномодулирующих эффектов пробиотических штаммов L. rhamnosus K32, B. longum GT15 (B), E. faecium L-3, оказывающих различное влияние на микробиоту кишечника.

There was a decrease in numbers of Escherichia coli with normal enzymatic activity, which was replaced by atypical forms of E. coli, Enterobacter spp. and fungi of the genus Candida, and, during treatment with GA, by atypical forms of E. coli, Proteus spp., Parvimonas micra. These differences indicate the effect of the therapy on the intestinal microbiota composition.

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The biological effects of three probiotic strains Lactobacillus rhamnosus K32, Bifidobacterium longum GT15, Enterococcus faecium L3 and their mixture were studied using a model of dysbiosis induced in rats by antibiotics. It was found that after taking different probiotics intestinal microbiota changed in a strain-specific manner. The maximal activity against pathogens was revealed after the administration of a mixture of bacterial strains under study or a single strain of enterococci. The strain E. faecium L3 showed the most activity against both Klebsiella spp. and Bacteroides fragilis. It helped to restore the original content of Faecalibacterium prausnitzii. The number of Klebsiella spp. was the same in the group receiving L. rhamnosus K32 and the group of animals, which was not consuming probiotics. Different probiotic strains included in the composition had various immunological effects. Probiotic bifidobacteria, enterococci and the mixture of three probiotics stimulated of mRNA expression of interleukin (IL)-10 in mesenteric lymph nodes. The changes in microbiota after consuming an enterococcal probiotic correlated with an increase in transforming growth factor (TGF)-β and IL-10 content in blood serum and an increase of the intestinal mucus layer. Consumption of L. rhamnosus K32 led to the stimulation of IL-8 expression in mesenteric lymph nodes. Control group not receiving probiotics was characterised by expression of pro-inflammatory cytokines, damage of epithelial cells and the destruction of their tight junctions. The damage to the ultrastructure of the mucosa was prevented in all the groups taking probiotics.

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