Profiling of Polar Metabolites in Mouse Feces Using Four Analytical Platforms to Study the Effects Of Cathelicidin-Related Antimicrobial Peptide in Alcoholic Liver Disease.

Alterations in gut bacterial homeostasis result in changes in intestinal metabolites. To investigate the effects of alcohol on fecal metabolites and the role of cathelicidin-related antimicrobial peptide (CRAMP) in alcoholic liver disease (ALD), CRAMP knockout (KO) and their control wild type (WT) mice were fed a Lieber-DeCarli liquid diet with or without alcohol. Polar metabolites in mouse feces were analyzed by GC × GC-MS and 2DLC-MS, and the concentrations of short chain fatty acids (SCFAs) were measured by GC-MS. A total of 95 and 190 metabolites were detected by GC × GC-MS and 2DLC-MS, respectively. Among the significantly changed metabolites, taurine and nicotinic acid were decreased in WT mice fed alcohol, which were also down-regulated in KO mice fed without alcohol. Interestingly, these two metabolites were increased in KO mice fed alcohol compared to them in WT controls. Additionally, SCFAs were significantly decreased in WT mice fed alcohol and in KO mice fed without alcohol, whereas two branched-chain SCFAs were increased by alcohol treatment in KO mice. In summary, the analytical platforms employed in this study successfully dissected the alterations of polar metabolites and SCFAs in fecal samples, which helped understand the effects of alcohol consumption and CRAMP in intestinal metabolism and alcohol-induced liver injury.