A Comprehensive Untargeted Metabonomic Analysis of Human Steatotic Liver Tissue by RP and HILIC Chromatography Coupled to Mass Spectrometry Reveals Important Metabolic Alterations

Steatosis, or excessive accumulation of lipids in the liver, is a generally accepted previous step to the development of more severe conditions like nonalcoholic steatohepatitis, fibrosis, and cirrhosis. We aimed, to characterize the metabolic profile that defines simple steatosis in human tissue and to identify potential disturbances in the hepatic metabolism that could favor the switch to progressive liver damage. A total of 46 samples, 23 from steatotic and 23 from nonsteatotic human livers, were analyzed following a holistic LC-MS-based metabonomic analysis that combines RP and HILIC chromatographic separations. Multivariate statistical data analysis satisfactorily classified samples and revealed steatosis-associated biomarkers. Increased levels of bile acids and phospholipid degradation products, and decreased levels of antioxidant species, were found in steatotic livers, indicating disturbances in lipid and bile acid homeostasis and mitochondrial dysfunction. Changes in hypoxanthine, creatinine, glutamate, glutamine, or gamma-glutamyl-dipeptides concentrations, suggestive of alterations in energy metabolism and amino acid metabolism and transport, were also found. The results show that the proposed analytical strategy is suitable to achieve a comprehensive metabolic profile of steatotic human liver tissue and provide new insights into the metabolic alterations occurring in fatty liver that could contribute to its predisposition to damage evolution.