The Use of Metabolomics to Explore the Gut-Liver Axis

Metabolomics is a relatively new and fast developing technology that covers a number of analytical profiling techniques and allows the measurement of hundreds of metabolites in almost any biological sample type. The gut-liver axis has been explored by metabolic profiling in a number of studies using various study designs, analytical techniques and data analysis strategies. The current chapter covers the human studies with the focus on the compounds released from the gut and the compounds known to affect liver disease, especially steatosis and steatohepatitis. These are mainly cross-sectional, “static” studies of contrasts between liver disease stages. More dynamic and flux-based human studies should be done as the field develops. Still some plausible mechanisms are revealed by the currently available metabolomics studies, including a range of metabolic changes in common with diabetes development; these changes can trigger a number of downstream imbalances which may partially explain why lipids accumulate and inflammation may increase. Some indications of the early changes in hepatic dyslipidemia have also been elucidated by metabolomics, however studies designed to catch the earliest signals triggering these events are still not available. Further development of metabolomics and of its application in the study of the gut-liver axis should provide a real potential to identify and understand the earliest events in disease onset and help explain the differences in the rate of progression.