[Composition of gut microbiota and characteristics of virulence factors genes in overweight or obese children and their relationship with liver metabolic inflammation].

Objective: To explore the composition of gut microbiome, the characteristics of virulence factor genes and their relationship with liver metabolic inflammation in overweight or obese children. Methods: A case-control design was conducted. From the children who visited the West China Second University Hospital of Sichuan University for medical or physical examinations between August 2021 and April 2022, a total of 23 obese children (obesity group), 8 overweight children (overweight group), and 22 healthy children (control group) were recruited. The body mass index of children was calculated after anthropometric measurements; metabolic inflammation indexes such as the levels of fasting blood glucose and hepatic function and renal function etc. were detected. The composition and abundance of gut microbiota in the feces of the children were detected by metagenomic sequencing technology and the Shannon index and Simpson index were calculated to assess the α diversity of virulence factor genes. The Wilcoxon rank-sum test was used for pairwise comparison between groups. The Spearman's rank correlation test was used for correlation analysis, and the Benjamini-Hochberg method was used to correct the P-value of multiple tests. Results: The obese group included 23 children aged 8.5 (6.3, 11.8) years, of whom 9 (39%) were male. The overweight group consisted of 8 children aged 9.2 (5.5, 12.3) years, of whom 4 were male. The control group comprised 22 children aged 5.3 (5.1, 5.4) years, of whom 10 (45%) were male. The obese group exhibited higher levels of alanine aminotransferase (ALT), gamma-glutamyl transferase (γ-GT), globulin, and uric acid compared to those of the control group (all P<0.05), with ALT also higher than that of the overweight group (P<0.05). The levels of fasting blood glucose, γ-GT, globulin, and uric acid in the overweight group were all higher than those in the control group (all P<0.05). The abundance of Coprococcus A (0.76 (0.00, 3.11) vs. 0.00 (0.00, 0.00), false discovery rate (FDR)<0.05) and Parasutterella (0.89 (0.08, 1.79) vs. 0.00 (0.00, 0.08), FDR<0.05) in the gut of children in the obese group were both higher than those of the control group. The number of virulence factor genes in the obese group was higher than those of the control group (941 (886, 977) vs. 890 (807, 920), P<0.05). The Simpson index and Shannon index of gut microbial virulence factor genes in the obese group were both higher than those of the control group (0.993 (0.992, 0.993) vs. 0.991(0.990, 0.991), (5.50 (5.46, 5.56) vs. 5.37 (5.30, 5.43), both P<0.01). The abundance of gut microbiota virulence factors genes all showed positive correlations with fasting blood glucose, ALT, γ-GT, and uric acid levels in children (all r>0.3, all FDR<0.05). The abundance of 17 gut microbial virulence factor genes were all positively associated with γ-GT levels (all r>0.3, all FDR<0.05). The virulence factor genes (LpxH, LpxB, LpxK) of lipopolysaccharide were all positively correlated with plasma γ-GT and globulin levels (all r>0.3, all FDR<0.05). Conclusions: Overweight or obese children exhibited elevated liver metabolic-inflammatory markers compared to their normal-weight counterparts. Notably, obese children demonstrated gut microbiota dysbiosis accompanied by enrichment of virulence factor genes, which may promote liver metabolic inflammation through pathways such as lipopolysaccharide biosynthesis.