Abstract
BACKGROUND & AIMS: Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) and Metabolic Dysfunction-Associated Steatohepatitis (MASH) represent progressive stages of liver disease, with distinct metabolic and cellular alterations. This study investigates the progression from MASLD to MASH through metabolomics, lipidomics, and assessment of hormones. METHODS: Male C57BL/6NTac mice were fed a high-fat diet for 16 weeks to induce MASLD and for 29 weeks to develop MASH. Aged-matched controls on a normal diet were used for comparison. Histology confirmed the progression of MASLD to MASH. We performed metabolomic and lipidomic profiling of liver, colon, and stool samples to identify metabolic and lipid alterations. Plasma enteroendocrine hormones and cytokines were quantified. Immunofluorescence was performed to assess enteroendocrine cells changes in the colon and the association of serotonin (5-HT) with fibronectin in the liver. RESULTS: Metabolomic and lipidomic analysis revealed significant alterations at different stages of the disease. Specifically, cholic acid was increased across the liver, colon, and stool in both MASLD and MASH mice compared to controls. Compared to the control group, MASLD mice exhibited an increase in enteroendocrine hormones, GLP-1, GIP, and PYY, whereas no changes were observed in MASH mice. Comparing MASLD to MASH livers, we found hepatic 5-HT levels were increased in MASH mice compared to MASLD mice. The MASH liver also exhibited a colocalization between fibronectin and 5-HT, suggesting a potential role of 5-HT in liver fibrosis. CONCLUSIONS: Our study provides novel insights into the progressive metabolic and hormonal changes from MASLD to MASH. The increase in cholic acid and differential enteroendocrine hormone responses highlight the complex interactions between the gut and liver in metabolic liver diseases. These findings suggest that enteroendocrine hormones may play a role in the progression of MASLD to MASH as well as liver fibrosis, offering potential therapeutic avenues for targeting the gut-liver axis in metabolic liver diseases.