The role of the gut microbiota in the pathogenesis of childhood obesity: structural and species-specific changes and their clinical significance

Analyzing the structural and species composition of the intestinal microbiota is an important tool for understanding the pathogenesis of obesity in children. The objective was to carry out a comparative analysis of the taxonomic diversity and quantitative characteristics of the colonic microbiota in obese children and their healthy peers aged 6–9 years. Patients and methods. The study included 154 children with exogenous-constitutional obesity (SDS BMI >2.0) and 49 children without obesity (SDS ИМТ -1…1 – control group) aged 6–9 years. To assess the qualitative and quantitative composition of the microbiota, the polymerase chain reaction (PCR) method was used using the ENTEROFLOR Children reagent kit (DNATechnology LLC, Russia). The Mann–Whitney test was used to compare the groups. Data visualization was performed using heat maps showing correlations between microorganisms. The results of the study showed that obese children have statistically significant differences in individual taxa of the microbiota. In particular, there was an increase in the total number of bacteria (p = 0.006), mainly due to representatives of the phylum Bacteroidota (p < 0.001), as well as Prevotella spp. (p = 0.000), Clostridium leptum (p = 0.038), Veillonellaceae (p = 0.001) and Faecalibacterium prausnitzii (p = 0.006). At the same time, a decrease in the number of Bifidobacterium spp. (p = 0.004) and Akkermansia muciniphila (p = 0.017), which have a protective effect in the formation of the intestinal microbiota, was recorded. Analysis of the Bacillota/Bacteroidota ratio showed a significant decrease in obese children compared to controls (p = 0.004). At the same time, an increase in Prevotella/Bacteroides ratio (p = 0.008) showed a more stable association with obesity, confirming its potential diagnostic significance. Correlation analysis revealed a weakening of intertaxon relationships in obese children and the absence of negative correlations between protective and opportunistic bacteria. In the control group, inverse correlations of A. muciniphila and Bifidobacterium spp. with Fusobacteriaceae were established, reflecting the presence of mechanisms of regulation of microbial homeostasis. Conclusion. The results obtained confirm the involvement of changes in the intestinal microbiota in the pathogenesis of obesity and emphasize the advisability of its assessment in the development of individualized prevention and therapy strategies.