[Association between obesity with the diversity and genus of gut microbiota in school-aged children]

Objective: To analyze the diversity differences of gut microbiota between school-aged obese children and normal-weight children and identify the characteristic flora in obese children to provide some evidence for the subsequent study of the following study-related mechanisms and the prevention and treatment of obesity in school-aged children. Methods: This study was based on a cohort established in a primary school in Jiading district, Shanghai, 2016. Sixty-three children, including 43 boys and 20 girls, who were obese during the three years from 2016 to 2018, were enrolled in the obesity group. Among children who were average weight for three years, a total of 63 were selected as the control group, with matching with the obese ones in a 1 to 1 way according to age, sex and class. The primary characteristics, diet status, breastfeeding, and other information of children were collected by questionnaire. Fecal samples of participants in both groups were collected, and 16S rDNA sequencing was performed. Operable taxon units clustering according to 97% similarity and species annotation were based on the quality-optimized sequences. The difference in the diversity and genius of gut microbiota among children in the obesity and control groups were analyzed. The α diversity indices, including Ace, Chao1, Shannon, and Simpson index, were calculated. The β diversity was presented based on unweighted Unifrac distance and weighted Unifrac space by principal coordinate analysis. The differences in β diversity between the two groups were compared by similarity analysis (ANOSIM).The differences in genus distribution between the two groups were selected by STAMP software. The association of obesity with the α diversity and genus with significant differences were analyzed by the generalized linear model (GLM). Results: The Ace and Chao1 index in the obesity group was significantly lower than those in the control group (The P values were 0.026 and 0.039, respectively). There was no significant difference in Shannon and Simpson index between the two groups (The P values were 0.879 and 0.922, respectively). The results of ANOSIM showed differences in gut microbiota between the two groups (R>0), but the group contribution was not significant (unweighted Unifrac distance: R=0.006, P=0.223; weighted Unifrac distance: R=0.010, P=0.134). Among the obese group, the relative abundance of Prevotella and Sarcina was highest in the endemic genus. The STAMP results showed that the relative lots of 15 genera were significantly different between the two groups (P<0.05). The results of GLM showed that, compared with the control group, the obesity group had a lower level of the relative abundance in Akkermansia muciniphila, while a higher level in Coprococcus_3, Ruminococcus, Agathobacter and Collinsella. After stratification by sex, the Chao1 index was also lower in the obese boys than that in the normal-weight boys. However, the obese girls only had a higher level in Coprococcus_3 than the ordinary weight girls. Conclusions: Compared with children with average weight, obese children had lower α diversity of gut microbiota and lower relative abundance of dominant probiotics but had a higher relative lot of genus associated with metabolic disorders, inflammation promotion, and metabolism rate reduction.