Metagenomic analysis of oral microbiota in Chinese children with obesity.

Childhood obesity represents an increasingly severe global public‑health concern, whose precise etiology remains incompletely elucidated and is likely multifactorial. In addition to genetic and lifestyle factors, mounting evidence indicates that the microbes in the digestive tract play a crucial role in the development and progression of obesity. Among them, the oral microbiota may contribute to obesity through mechanisms such as inducing systemic chronic inflammation and promoting gut microbiota dysbiosis. In the present study, saliva samples were collected from 9 obese children and 9 normal-weight children. Using metagenomic sequencing, we aimed to analyze the structural characteristics and functional profiles of the oral microbiota in Chinese school‑age children with obesity, so as to comprehensively dissect the oral microbiome ecology of this population from structural and functional perspectives. The results revealed that the microbiota diversity was similar between the two groups. At the species level, Dialister invisus, Treponema porcinum, Moraxella sp., Moraxella sp. VT 16 12, Moraxella lacunata, and Moraxella caprae were significantly enriched in the normal-weight group. Conversely, Campylobacter concisus, Veillonella sp. oral taxon 158, Veillonella rogosae, Veillonella sp. S13053 19, Streptococcus ilei, and Streptococcus australis were significantly enriched in the obese group. Functional annotation analysis demonstrated significant enrichment of functional genes associated with the hypoxia-inducible factor-1 (HIF-1) signaling pathway, peroxisome proliferator-activated receptor (PPAR) signaling pathway, beta-alanine metabolism, AMP-activated protein kinase (AMPK) signaling pathway, and apoptosis in the normal-weight group. In contrast, functional genes related to biofilm formation-Vibrio cholerae, selenocompound metabolism, RNA polymerase, xylene degradation, and dioxin degradation were significantly enriched in the obese group. Correlation analysis further revealed strong positive correlations between Veillonella sp. oral taxon 158, Veillonella sp. S13053 19, Streptococcus ilei, Streptococcus australis and the functional pathways of biofilm formation-Vibrio cholerae, selenocompound metabolism, xylene degradation, and dioxin degradation. These observations suggest that the oral microbiome undergoes compositional and functional alterations in children with obesity, implying a potential role of oral microbiota in the etiology of childhood obesity.