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007 - CCFC STUDENT PRIZE TB Murdoch, H Fu, S Martin, CM Slupsky, RN Fedorak BACKGROUND: Metabolomics, the study of small-molecule metabolite profiles, is a novel method of investigating disease. Nuclear magnetic resonance spectroscopy (NMR) has been shown to be effective for simultaneously identifying and quantifying hundreds of small molecules in complex mixtures of bio-fluids and tissues. Recent metabolomic studies have demonstrated that urinary metabolic profiles can be altered by enteric bacteria. Inflammatory bowel disease (IBD) is known to be associated with marked changes in enteric bacterial profiles.
Division of Gastroenterology, Department of Medicine University of Alberta, Edmonton, Alberta
OBJECTIVE: To investigate whether IBD confers a distinct metabolic 'fingerprint' that could be used as a diagnostic tool for this disease, and to examine the contribution of enteric bacteria to this 'fingerprint' and thus to the pathogenesis of IBD.
METHODS: IL-10 gene-deficient mice (IL10KO) (N=4), which develop IBD similar to human Crohn's disease, were compared to age- and sex-matched wild-type controls (N=3). At 4, 8 and 16 wk of age, 22 h urine samples were obtained. At 20 wk of age, the mice were sacrificed, their colons removed, homogenized and subjected to methanol/chloroform extraction followed by lyophilization. Urine and colonic tissue extract samples were run on a Varian 600 MHz NMR spectrometer and metabolite concentrations were determined using Chenomx NMRSuite 4.0 (Chenomx Inc, Edmonton, Canada). Statistical analysis was conducted using Principal Components Analysis (PCA) using standard procedures as implemented in SIMCA P11.0 (Umetrics, Umeå, Sweden). The Student's t-test was used to determine significance.
RESULTS: PCA of urine and colonic extracts revealed that IL10KO mice with IBD had markedly different metabolic profiles relative to their matched wild-type controls. Loading plots revealed the following separating metabolites: methylamines, purine metabolites, and citric acid cycle intermediates. Most dramatically, trimethylamine (TMA) revealed significantly increased levels in IL10KO mouse urine at 8 (p=0.03) and 16 (p=0.02) wks of age as compared to wildtype mice, paralleling the histologic development of IBD and change in luminal microflora.
CONCLUSION: This study demonstrates the potential of urine NMR metabolomic 'fingerprinting' as a diagnostic technique for IBD. Moreover, our ongoing metabolomic studies may provide insight into the etiology of IBD. TMA production in the mouse has been shown to be dependent on the presence and composition of enteric microflora. Identification of the bacteria responsible for TMA production may assist in identifying the microbial factors responsible for initiation and perpetuation of IBD.