Metabolic Phenotyping Study of Mouse Brain Following Microbiome Disruption by C.difficile Colonization.

Clostridioides difficile infection (CDI) is responsible for an increasing number of cases of post-antibiotic diarrhea worldwide, which has high severity and mortality among hospitalized elderly patients. The disruption of gut microbiota due to antibacterial medication facilitates the intestinal colonization of C. difficile. In the present study, a murine model was used to investigate the potential effects of antibiotic administration and subsequent colonization by C. difficile, as well as the effects of three different 10-day treatments (metronidazole, probiotics, and fecal microbiota transplantation), on the brain metabolome for the first time. Four different metabolomic-based methods (targeted HILIC-MS/MS, untargeted RP-LC-HRMS/MS, targeted GC-MS/MS, and untargeted GC-MS) were applied, resulting in the identification of 217 unique metabolites in the brain extracts, mainly glycerophospholipids, glycerolipids, amino acids, carbohydrates, and fatty acids. Univariate and multivariate statistical analysis revealed that CDI, as well as the subsequent treatments, altered significantly several brain metabolites, probably due to gut dysbiosis, and affected the brain through the gut-brain axis. Notably, none of the therapeutic approaches completely restored the brain metabolic profile to the original, healthy, and non-infected phenotype, even after 10 days of treatment.

Metabolic consequences for mice lacking Endosialin: LC-MS/MS-based metabolic phenotyping of serum from C56Bl/6J Control and CD248 knock-out mice.

INTRODUCTION: The Endosialin/CD248/TEM1 protein is expressed in adipose tissue and its expression increases with obesity. Recently, genetic deletion of CD248 has been shown to protect mice against atherosclerosis on a high fat diet. OBJECTIVES: We investigated the effect of high fat diet feeding on visceral fat pads and circulating lipid profiles in CD248 knockout mice compared to controls. METHODS: From 10 weeks old, CD248-/- and +/+ mice were fed either chow (normal) diet or a high fat diet for 13 weeks. After 13 weeks the metabolic profiles and relative quantities of circulating lipid species were assessed using ultra high performance liquid chromatography-quadrupole time-of flight mass spectrometry (UHPLC-MS) with high resolution accurate mass (HRAM) capability. RESULTS: We demonstrate a specific reduction in the size of the perirenal fat pad in CD248-/- mice compared to CD248+/+, despite similar food intake. More strikingly, we identify significant, diet-dependent differences in the serum metabolic phenotypes of CD248 null compared to age and sex-matched wildtype control mice. Generalised protection from HFD-induced lipid accumulation was observed in CD248 null mice compared to wildtype, with particular reduction noted in the lysophosphatidylcholines, phosphatidylcholines, cholesterol and carnitine. CONCLUSIONS: Overall these results show a clear and protective metabolic consequence of CD248 deletion in mice, implicating CD248 in lipid metabolism or trafficking and opening new avenues for further investigation using anti-CD248 targeting agents.

Endogenous and xenobiotic metabolite profiling of liver extracts from SCID and chimeric humanized mice following repeated oral administration of troglitazone.

1. Metabonomic analysis, via a combination of untargeted and targeted liquid chromatography-mass spectrometry (LC-MS) and untargeted (1)H NMR spectroscopy-based metabolite profiling, was performed on aqueous (AQ) and organic liver extracts from control (SCID) and chimeric humanized (PXB) mice dosed with troglitazone at 0, 300 and 600 mg/kg/day for seven days. 2. LC-MS analysis of AQ liver extracts showed a more "human-like" profile for troglitazone metabolites for PXB, compared with SCID, mice. 3. LC-MS detected differences in endogenous metabolites, particularly lipid species in dosed mice, including elevated triacylglycerols and 1-alkyl,2-acylglycerophosphates as well as lowered diacylglycerophosphocholines and 1-alkyl,2-acylglycerophosphocholines for PXB compared with SCID mouse liver extracts. Following drug administration changes in the relative proportions of the ions for various unsaturated fatty acids were observed for both types of mouse, some of which were specific to PXB or SCID mice. 4. (1)H NMR spectroscopy revealed that AQ PXB mouse liver extracts had elevated amounts of inosine, fumarate, creatine, aspartate, trimethylamine N-oxide, glycerophosphocholine, phosphocholine, choline, glutamine, glutamate, acetate, alanine and lactate relative to SCID mice and decreased histidine, glycogen, α- and ß-glucose, taurine, and glutathione. Increased uracil and tyrosine concentrations were detected for PXB mice on troglitazone administration. 5. Metabonomic profiling thus showed clear differences between humanized and SCID mice, including after administration of troglitazone.

Global metabolite profiling of human colorectal cancer xenografts in mice using HPLC-MS/MS.

Reversed-phase gradient LC-MS was used to perform untargeted metabonomic analysis on extracts of human colorectal cancer (CRC) cell lines (COLO 205, HT-29, HCT 116 and SW620) subcutaneously implanted into age-matched athymic nude male mice to study small molecule metabolic profiles and examine possible correlations with human cancer biopsies. Following high mass accuracy data analysis using MS and MS/MS, metabolites were identified by searching against major metabolite databases including METLIN, MASSBANK, The Human Metabolome Database, PubChem, Biospider, LipidMaps and KEGG. HT-29 and COLO 205 tumor xenografts showed a distribution of metabolites that differed from SW620 and HCT 116 xenografts (predominantly on the basis of relative differences in the amounts of amino acids and lipids detected). This finding is consistent with NMR-based analysis of human colorectal tissue, where the metabolite profiles of HT-29 tumors exhibit the greatest similarity to human rectal cancer tissue with respect to changes in the relative amounts of lipids and choline-containing compounds. As the metabolic signatures of cancer cells result from oncogene-directed metabolic reprogramming, the HT-29 xenografts in mice may prove to be a useful model to further study the tumor microenvironment and cancer biology.