Obesity and functional bowel disorders (FBDs) are often observed in children and have common risk factors. The present review aimed to summarize the published data on the association between obesity and FBDs in children and a discussion of possible pathophysiological mechanisms that may be involved. Published data indicates that obesity and FBDs could be associated conditions. There is substantial evidence that obesity in children is associated with constipation. However, it should be noted that there were few studies in this direction, and those studies were heterogeneous in both the composition of participants and studied diagnostic criteria, and in the majority of cases, they were not adjusted for potential confounders. The association between obesity and FBDs can be explored through diet, peculiarities of eating behavior, and psychological factors. The most promising direction in the study could be the study of the GM, the changes in which can contribute to the development of immune dysfunctions of the bowel, chronic low-grade inflammation, increased colonic permeability, motility disturbances, and visceral hypersensitivity. The studies in this area can provide important data for developing a strategy of treatment and prevention of both groups of diseases.

Childhood obesity is a worldwide serious health issue leading to endocrine disruption. Childhood obesity risk factors are numerous, and in recent decades the significant impact of gut microbiota in the development of obesity has been shown (1). In turn, gut microbiota development can be disrupted by many factors in the early postnatal period, particularly by breastfeeding duration. Although studies were pointing out the impact of short breastfeeding period on the obesity-associated microbiota formation in childhood (2), the long-termed effect still remains poorly explored. Therefore, we assumed a contribution of breastfeeding duration to the gut microbiota composition in adolescents with obesity. The total cohort was 40 adolescents who were divided into four categories: 9 obese and 11 healthy adolescents who had been breastfed less than four months (SDS BMI=2.83±0.40 and SDS BMI=-0.17±0.55 correspondingly); 9 obese and 11 healthy adolescents who had been breastfed more than four months (SDS BMI=2.70±0.69 and SDS BMI=0.19±0.38). The mean breastfeeding duration was significantly different between the four groups (p=0. 0001). The metagenome sequencing of V3-V4 variable regions of 16S rRNA was done by Novogene Company (China) on the Illumina platform. Bacteria number of gut microbiota was presented as normalized values. Data was shown as median, lower and upper quartile, and compared by the pairwise Mann-Whitney U Test. Statistical significance was accepted at p<0. 05. The Shannon and Simpson diversity indices as well as the ACE and Chao species richness indices of the adolescents’ gut microbiota were not differed for each group. We did not find any significant variations for the main phyla Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria. At the family level, the U Test indicated a significant increase in the abundance of the phylotype Ruminococcaceae UCG-014 in adolescents with obesity who were breastfed for four months or less as compared to the group with obesity and breastfeeding more than four months (365 (137; 499) and 99 (72; 149) correspondingly,р=0. 01, Z adjusted=-2.43). Moreover, adolescents with normal weight regardless of breastfeeding duration had similar amount of RuminococcaceaeUCG-014 as adolescents who were breastfed until four months and having obesity (145 (110; 381) for the group with normal weight and breastfeeding<4 months and 154 (96; 245) for the group with normal weight and breastfeeding > 4 months). The family Ruminococcaceae belongs to the phylum Firmicutes, which was proved before as a phylum increasing in gut microbiota of individuals with obesity (1). Our results confirmed that and furthermore, revealed the impact of short overall breastfeeding duration on the gut microbiota composition through an increased abundance of bacteria belonging to the family Ruminococcaceaein adolescents with obesity. Reference: (1) Turnbaugh et al. Nature. 2006 Dec 21;444(7122): 1027-31. (2) Forbes et al. JAMA Pediatr. 2018 Jul 2;172(7): e181161. Presentation: No date and time listed

Background: It is known that in the early postnatal period a variety of factors affect the gut microbiota (GM) composition, including delivery mode. The effect of delivery mode on the human GM in the late postnatal period remains unexplored. A shift of GM composition due to delivery mode may contribute to the development of obesity in adulthood. Methods and Results: The study included six adolescents aged between 11 and 17 years treated and examined at the Clinic of the Scientific Center for Family Health and Human Reproduction (Irkutsk, Russia) in 2016. Stool samples were collected following the standard operating procedures according to the International Human Microbiome Standards. Metasequencing of V3-V4 variable regions of the 16S rRNA gene was performed by the Novogene Company (China) on the Illumina platform. Bioinformatic analysis was done by the bri-shur.com services. Sequencing reads were presented as normalized values. In general, the GM composition of obese adolescents born by cesarean section was characterized by composition heterogeneity within the Bacteroidetes phylum and the dominance of certain phylotypes as signs of dysbiosis for each adolescent. We detected an increased abundance of phyla Bacteroides and Proteobacteria, and an absence of Tenericutes in obese adolescents born by Caesarean section. On the level of genera, the prevalence of Bacteroides and Bacteroides S24-7 phylotypes, and the absence of the RF39 phylotype, led to the GM shift associated with a cesarean section or obesity. Conclusion: Obese adolescents born by cesarean section delivery present the shift in GM composition.