Xenometabolite signatures in the UC Davis type 2 diabetes mellitus rat model revealed using a metabolomics platform enriched with microbe-derived metabolites.

The gut microbiome has the potential to create or modify xenometabolites (i.e., nonhost-derived metabolites) through de novo synthesis or modification of exogenous and endogenous compounds. While there are isolated examples of xenometabolites influencing host health and disease, wide-scale characterization of these metabolites remains limited. We developed a metabolomics platform ("XenoScan") using liquid chromatography-mass spectrometry to characterize a range of known and suspected xenometabolites and their derivatives. This assay currently applies authentic standards for 190 molecules, enriched for metabolites of microbial origin. As a proof-of-principle, we characterized the cecal content xenometabolomics profile in adult male lean Sprague-Dawley (LSD) and University of California, Davis type 2 diabetes mellitus (UCD-T2DM) rats at different stages of diabetes. These results were correlated to specific bacterial species generated via shotgun metagenomic sequencing. UCD-T2DM rats had a unique xenometabolite profile compared with LSD rats, regardless of diabetes status, suggesting that at least some of the variation is associated with host genetics. Furthermore, modeling approaches revealed that several xenometabolites discriminated UCD-T2DM rats at early stages of diabetes versus those at 3 mo postdiabetes onset. Several xenometabolite hubs correlated with specific bacterial species in both LSD and UCD-T2DM rats. For example, indole-3-propionic acid negatively correlated with species within the genus in UCD-T2DM rats considered to be prediabetic or recently diagnosed diabetic, in contrast to gluconic acid and trimethylamine, which were positively correlated with species. The application of a xenometabolite-enriched metabolomics assay in relevant milieus will enable rapid identification of a wide variety of gut-derived metabolites, their derivatives, and their potential biochemical origins of xenometabolites in relationship to host gastrointestinal microbial ecology. We debut a liquid chromatography-mass spectrometry (LC/MS) platform called the XenoScan, which is a metabolomics platform for xenometabolites (nonself-originating metabolites). This assay has 190 in-house standards with the majority enriched for microbe-derived metabolites. As a proof-of-principle, we used the XenoScan to discriminate genetic differences from cecal samples associated with different rat lineages, in addition to characterizing diabetes progression in rat model of type 2 diabetes. Complementing microbial sequencing data with xenometabolites uncovered novel microbial metabolism in targeted organisms.