The gut microbiota plays an important role in maintaining human health, as well as in the development of various pathologies, as indicated by a large amount of research. One of the manifestations of an imbalance in the gut microbiome composition is the appearance of various diseases or immune reactions, in particular, atopic dermatitis (AD) and/or food allergies (FA). In this research, using 16S NGS sequencing, it was found that the gut microbiome of children with food allergies and children with atopic dermatitis can be characterized as having higher inflammatory potential. Both groups exhibited an abundance of representatives from the Pasteurellaceae and Erysipelotrichaceae families, as well as a decrease in the relative number of representatives from the Barnesiellaceae family compared to healthy participants. In the group of participants with food allergies, there was a decrease in the relative number of Desulfovibrionaceae representatives and Bifidobacteriaceae family enrichment in relatively healthy participants. In addition, when comparing this group with patients with atopic dermatitis, it was revealed that a number of representatives of such families as Erysipelotrichaceae, Ruminococcaceae and Sutterellaceae prevailed. This information confirms that AD and FA correlate with changes in the composition of the gut microbiota. Further research is needed to determine the cause–effect connections and the effect of compounds derived from the microbiota on the AD and FA development and progression, as well as to create new probiotic drugs to prevent and modulate immune responses, including at an early age.

Background. Currently, it is known that the gut microbiota plays an important role in the functioning of the immune system, and a rebalancing of the bacterial community can arouse complex immune reactions and lead to immune-mediated responses in an organism, in particular, the development of atopic dermatitis (AD). Cytokines and chemokines are regulators of the innate and adaptive immune response and represent the most important biomarkers of the immune system. It is known that changes in cytokine profiles are a hallmark of many diseases, including atopy. However, it remains unclear how the bacterial imbalance disrupts the function of the immune response in AD. Objectives. We attempted to determine the role of gut bacteria in modulating cytokine pathways and their role in atopic inflammation. Methods. We sequenced the 16S rRNA gene from 50 stool samples of children aged 3–12 years who had confirmed atopic dermatitis, and 50 samples from healthy children to serve as a control group. To evaluate the immune status, we conducted a multiplex immunofluorescence assay and measured the levels of 41 cytokines and chemokines in the serum of all participants. Results. To find out whether changes in the composition of the gut microbiota were significantly associated with changes in the level of inflammatory cytokines, a correlation was calculated between each pair of bacterial family and cytokine. In the AD group, 191 correlations were significant (Spearman’s correlation coefficient, p ≤ 0.05), 85 of which were positive and 106 which were negative. Conclusions. It has been demonstrated that intestinal dysbiosis is associated with alterations in cytokine profiles, specifically an increase in proinflammatory cytokine concentrations. This may indicate a systemic impact of these conditions, leading to an imbalance in the immune system’s response to the Th2 type. As a result, atopic conditions may develop. Additionally, a correlation between known AD biomarkers (IL-5, IL-8, IL-13, CCL22, IFN-γ, TNF-α) and alterations in the abundance of bacterial families (Pasteurellaceae, Barnesiellaceae, Eubacteriaceae) was observed.

Beneficial properties of lactic acid bacteria have been known long ago, but particular interest in probiotics has arisen in the last two decades due to the understanding of the important role of intestinal microflora in human life. Thus, the ability of probiotics to support healthy homeostasis of gut microbiomes has received particular attention. Here, we evaluated the effect of a probiotic consisting of Bifidobacterium longum and Lacticaseibacillus paracasei on the gut microbiome of male rats, assessed their persistence in the fecal biota, and compared probiotic-mediated changes in vitro and in vivo. As expected, microbiomes of two enterotypes were identified in the feces of 21 animals, and it turned out that even a single dose of the probiotic altered the microbial composition. Upon repeated administration, the E1 biota temporarily acquired properties of the E2 type. Being highly sensitive to the intervention of probiotic bacteria at the phylum and genus levels, the fecal microbiomes retained the identity of their enterotypes when transferred to a medium optimized for gut bacteria. For the E2 biota, even similarities between probiotic-mediated reactions in vitro and in vivo were detected. Therefore, fecal-derived microbial communities are proposed as model consortia to optimize the response of resident bacteria to various agents.

Background. In many studies over the past decade, scientists have made a connection between the composition of gut microbiota and human health. A number of publications have shown that gut bacteria are involved in many metabolic and physiological processes of the organism. The composition of the gut microbiome is unique for each person and is formed under the influence of various factors associated with both the individual characteristics of the body and the characteristics of the environment. Different regional characteristics make it necessary for the body to adapt to certain conditions, including temperature fluctuations. Living in areas with low temperatures, such as the Arctic zone, dictates the need for increased energy consumption, which affects the composition of the gut microbiome. Methods. In our study, an extensive questionnaire was conducted among the participants, where many questions were included about the dietary preferences of the study participants, which allowed them us to further divide them into groups according to their diets. Stool samples were collected from participants from 3 groups: Arctic native, Arctic newcomer and the control group. The next step was the isolation of bacterial DNA and sequencing the 16S rRNA gene. The analysis of the results of the diversity of the intestinal microbiota was carried out both with and without taking into account the dietary preferences of the participants. Results. As a result of comparing the intestinal microbiota obtained from residents of the Arctic zone with the gut microbiota of residents of other regions with a milder climate, significant differences are found. These differences may be related to limited food resources and a reduction in the variety of food products characteristic of this Arctic region. t was also found that representatives of the bacterial families Christensenellaceae and Muribaculaceae dominated the control group, both with traditional nutrition and with a dairy-free diet in comparison with the Arctic groups. The control group was dominated by representatives of the Prevotellaceae, Enterobacteriaceae and Comamonadaceae families compared to the Arctic group (with a traditional diet). The results also show that the number of representatives of the families Desulfovibrionaceae (with traditional diet) and Enterobacteriaceae (with milk-free diet) is growing in the Arctic group. Conclusions. In the course of this work, bacterial families characteristic of people living in the Arc-tic zone of the Far Eastern region of the Russian Federation were identified. Poor diet, difficult climatic conditions, and problems with logistics and medical care can have a strong impact on the health of this population. The main type of diet for the inhabitants of the Arctic is the traditional type of diet. They consume a large number of low-cost products, obtainget animal protein from poultry and canned food, and also eat a small number of fresh vegetables and fruits. Such a diet is due to the social status of the study participants and the climatic and geographical features of the region (difficulties in agriculture). With such a diet, we observe a decrease in representatives of the Christensenellaceae, Muribaculaceae, Eubacteriaceae, and Prevotellaceae families and an increase in representatives of the Enterobacteriaceae and Desulfovibrionaceae families among Arctic residents. This imbalance in the futuremay cause, this population may to develop various diseases in the future, including chronic diseases such as obesity, intestinal dysbiosis, inflammatory bowel diseases, and type 2 diabetes.

It is known that the intestinal microbiome plays an important role in many biological processes of the human body. However, all factors and mechanisms influencing changes in the composition of the intestinal microbiome are not fully understood. As the results of previous studies show, long-term food preferences play a significant role in modulating the composition of the intestinal microbiota. At the same time, all the mechanisms fully reflecting the peculiarities of the relationship of vitamins, trace elements, and the composition of the intestinal microbiota are not adequately characterized. Vitamins and trace elements have a bidirectional effect on the intestinal microbiota. On the one hand, they influence the composition of the microbiota, its representation, number, and diversity. On the other hand, the microbiota is involved in the metabolism of trace elements, including the synthesis of certain vitamins. In this review, we have tried to summarize the currently known information reflecting the relationship between the main microelements and the bacterial community of the gut. The review showed that some vitamins, with additional use, entering the colon modulate its microbiome, increase and maintain the bacterial diversity of the gut microbiota, which affects the amount of synthesized short-chain fatty acids. Several vitamins, such as vitamins A and D, can also affect intestinal immunity and its barrier functions.

Introduction. Carbohydrates, including dietary sugars and prebiotic oligo- and polysaccharides, can influence on the functional activity of probiotic bacteria by modulating their metabolic processes. An important property of prebiotics is the selective activation of endogenous protective populations of intestinal microflora, which helps to suppress the growth of pathogenic and opportunistic microorganisms. However, the specificity of various prebiotic supplements for specific exogenous probiotic microorganisms remains unclear. Probiotics can be components of a wide range of foods and dietary supplements, so it is important to understand how various nutritional substrates influence on their metabolic and functional activity. This knowledge will enable the development of more effective products and supplements aimed at maintaining intestinal bacterial balance. ”In vitro” studies allow evaluating the effects of individual components on probiotic strains. In this work, the effect of various carbohydrate substrates on the antagonistic activity of exogenous probiotic strains Lactobacillus paracasei and Bifidobacterium longum against a number of opportunistic microorganisms was studied.Objective — to study the effect of various carbohydrate substrates, including well-known prebiotics, on the antagonistic activity of probiotic strains studied against opportunistic pathogens. The choice of a carbohydrate that improves the competitive properties of probiotic strains of L. paracasei and B. longum.Materials and methods. The antagonistic activity of two probiotic strains against seven pathogenic microorganisms was studied in the presence of nine different carbohydrate substrates using a two-stage cultivation method in a combined system.Results. Probiotic strains were established to exhibit selective antagonistic properties against the same pathogen, depending on the presence of a particular carbohydrate source. For example, lactose and sucrose were found to contribute to an increase in the degree of antagonistic activity of lactobacilli against Staphylococcus aureus from moderate to high relative to the control and other substrates, and inulin and FOS suppress the competitive properties of this strain relative to Pseudomonas aeruginosa. The studied strain of Bifidobacterium longum exhibits moderate antagonistic activity against E. coli and C. jejuni, however, a number of substrates (sucrose, mannitol, inulin, chitosan) are capable of inhibiting this property. At the same time, substrates such as lactose, maltose, sucrose, chitosan, and N-acetyl-D-glucosamine increase antagonistic activity from low to moderate against K.pneumoniae, P.aeruginosa, and A.baumannii. Based on the data obtained, it can be assumed that N-acetyl-D-glucosamine (NAG), mannitol, maltose, and lactose are of interest as substrates that increase the antagonistic potential of the studied strains against a number of opportunistic pathogens.Limitations. Antagonistic activity in co-cultivation of probiotic strains has not been studied. It is also difficult to assess the functional properties of the studied strains depending on the prebiotic in the gastrointestinal tract. In addition, the effect of the concentration of carbohydrate substrates used in the work on the antagonism of target probiotic strains has not been studied.Conclusion. We have identified a significant effect of the carbohydrate component on the antagonistic properties of the probiotic strains studied, which can be further taken into account in the development of probiotic compositions, synbiotics, and functional foods.Compliance with ethical standards. The study does not require the submission of a conclusion from the biomedical ethics committee or other documents.Contribution: Kalashnikova I.G. – concept and design of research, collection of material and data processing, writing text, conducting research; Nekrasova A.I. – concept and design of research, editing; Gritsyuk O.V., Fedets Z.E., Pankova M.N. – conducting research, methodology development; Zagainova A.V. – providing research, project administration; Zhernov Yu.V., Makarov V.V. – definition of the concept, attraction of financing, provision of research; Yudin S.M. – attraction of financing, provision of research. All authors are responsible for the integrity of all parts of the manuscript and approval of the manuscript final version.Conflict of interest. The authors declare no conflict of interest.Funding. The work was performed within the framework of the state task No. 388-00154-22-00 “Creation of micellar probiotics of a new generation for targeted changes in the composition of the human microbiota in chronic non-communicable diseases”.Received: October 2, 2025 / Revised: November 24, 2025 / Accepted: December 2, 2025 / Published: January 15, 2026