Hierarchical analysis of metabolic phenotype reveals distinct microbiota and circulatory transcriptome in metabolic dysfunction–associated steatotic liver disease

AIM: To investigate how visceral adiposity and insulin resistance, defined respectively by visceral adiposity index (VAI) and triglyceride-glucose (TyG) index, jointly influence gut microbiota composition and immune transcriptomes in metabolic dysfunction-associated steatotic liver disease (MASLD), and to explore potential mechanistic pathways. METHODS: We enrolled 169 adults stratified by VAI, controlled attenuation parameter (CAP), TyG index, and physical activity. Gut microbiota and immune transcriptomes were profiled using 16S rRNA and RNA sequencing, respectively. Differentially expressed genes (DEGs) were identified across subgroups. Functional annotation and upstream regulatory networks were analyzed using DAVID and Ingenuity Pathway Analysis (IPA). RESULTS: Higher VAI correlated with obesity, inflammation, and steatosis, while the TyG index independently predicted fibrosis risk. Specific taxa, includingTM7x,Acidaminococcus, andDielma, were consistently enriched in adverse metabolic phenotypes. Transcriptomic analysis of circulating immune cells identified 348 TyG-associated DEGs significantly enriched in mitochondrial and cytokine signaling pathways. IPA highlighted IL6, SREBF1, PTGS1 and SNCA as central regulators linking metabolic stress to mitochondrial dysfunction. CONCLUSIONS: Gut microbiota shifts and immune transcriptome alterations jointly mediate the interplay between insulin resistance and visceral adiposity in MASLD. The identified insulin resistance-associated genes suggest that mitochondrial dysfunction and cytokine dysregulation contribute to obesity-related hepatic pathology, supporting precision strategies targeting VAI and metabolic dysregulation.