Multi-Omics Analysis Identifies Tryptophan Metabolism and Glycolysis as Potential Pathways Involved in the Protective Effects of Tormentic Acid Against Metabolic Associated Fatty Liver Disease.

Metabolic associated fatty liver disease (MAFLD) has high morbidity and tragically lacks effective therapeutic remedies. Tormentic acid (TA) has been shown to have therapeutic effect on liver fibrosis, but its role in MAFLD remains unknown. Therefore, we employed multi-omics analyses to investigate the effects of TA on MAFLD. In this study, male C57BL/6J mice were fed a methionine- and choline- deficiency (MCD) diet to induce MAFLD and subsequently treated with TA for 4 weeks. The therapeutic efficacy of TA was then evaluated through histopathological examination and biochemical analysis. In addition, multi-omics analyses including transcriptomics, proteomics and metabolomics were conducted to identify potential pathways associated with TA treatment. Finally, key genes and proteins in the identified pathways were validated by qPCR and Western blot. Our results showed that TA significantly alleviated liver damage and excessive lipid accumulation. Importantly, our integrative multi-omics analyses identified tryptophan metabolism and glycolysis as pivotal pathways associated with TA treatment in our fatty liver mouse model. Subsequent validation demonstrated the TA-induced upregulation of IDO2 and HAAO, suggesting engagement of tryptophan metabolism. Concurrently, TA treatment downregulated HK2, PFKP, and PKM2, indicative of altered rate-limiting glycolytic enzyme expression. These findings suggest that TA alleviates MCD diet-induced MAFLD, potentially involving modulation of enzyme expression in tryptophan metabolism and glycolysis.