Multi-omics analyses of the gut microbiota and metabolites in children with metabolic dysfunction-associated steatotic liver disease

The development and severity of metabolic dysfunction-associated steatotic liver disease (MASLD) in children are closely related to alterations of gut microbiota. This study aims to investigate changes in the gut microbiota signature and microbial metabolites in children with MASLD. We collected fecal samples from children and adolescents aged 6-16 years, and the presence of MASLD was diagnosed by ultrasound. We performed 16S ribosomal DNA sequencing and targeted metabolomics in 36 and 25 subjects, consisting of healthy controls, children with obesity, and children with MASLD. The α-diversity was significantly lower in children with obesity and MASLD compared with healthy controls. Linear discriminant analysis of effect size analysis identified <i>Anaerostipes</i> and <i>A. hadrus</i> as the top biomarkers differentiating the obesity group from the MASLD group. In MASLD patients with high alanine aminotransferase values (≥50 U/L for boys and 44 U/L for girls), we observed a decrease in the gut microbiota health index. MASLD patients with high shear wave elastography (<i>E</i>) values (≥6.2 kPa) showed an increased abundance of <i>Ruminococcus torques</i>, which was positively correlated with the levels of deoxycholic acid (DCA) and <i>E</i> values. Importantly, the mediation analysis identified positive associations between <i>R. torques</i> and clinical indicators of MASLD that were mediated by DCA. Overall, our study suggests that gut microbiota and metabolites are significantly altered in children with MASLD, and targeting <i>R. torques</i> may offer potential benefits for disease management.IMPORTANCEThis study investigated alterations in the gut microbiota signature and microbial metabolites in children with metabolic dysfunction-associated steatotic liver disease (MASLD). We found that an increased abundance of <i>Ruminococcus torques</i> was associated with increased levels of deoxycholic acid and the progression of MASLD, suggesting that <i>R. torques</i> may serve as a novel clinical target in pediatric MASLD.