title: Faecal metabolite profiling identifies medium-chain fatty acids as discriminating compounds in IBD.
abstract: BACKGROUND
  Bacteria play a role in the onset and perpetuation of intestinal inflammation in IBD. Compositional alterations may also change the metabolic capacities of the gut bacteria.
  
  
  OBJECTIVE
  To examine the metabolic activity of the microbiota of patients with Crohn's disease (CD), UC or pouchitis compared with healthy controls (HC) and determine whether eventual differences might be related to the pathogenesis of the disease.
  
  
  METHODS
  Faecal samples were obtained from 40 HC, 83 patients with CD, 68 with UC and 13 with pouchitis. Disease activity was assessed in CD using the Harvey-Bradshaw Index, in UC using the UC Disease Activity Index and in pouchitis using the Pouchitis Disease Activity Index. Metabolite profiles were analysed using gas chromatography-mass spectrometry.
  
  
  RESULTS
  The number of metabolites identified in HC (54) was significantly higher than in patients with CD (44, p<0.001), UC (47, p=0.042) and pouchitis (43, p=0.036). Multivariate discriminant analysis predicted HC, CD, UC and pouchitis group membership with high sensitivity and specificity. The levels of medium-chain fatty acids (MCFAs: pentanoate, hexanoate, heptanoate, octanoate and nonanoate), and of some protein fermentation metabolites, were significantly decreased in patients with CD, UC and pouchitis. Hexanoate levels were inversely correlated to disease activity in CD (correlation coefficient=-0.157, p=0.046), whereas a significant positive correlation was found between styrene levels and disease activity in UC (correlation coefficient=0.338, p=0.001).
  
  
  CONCLUSIONS
  Faecal metabolic profiling in patients with IBD relative to healthy controls identified MCFAs as important metabolic biomarkers of disease-related changes.
  
  
  BACKGROUND
  NCT 01666717.
authors.affiliation: Translational Research Center for Gastrointestinal Disorders (TARGID) and Leuven Food Science and Nutrition Research Centre (LFoRCe), University Hospital Gasthuisberg, KU Leuven, Leuven, Belgium.
authors.forename: Vicky
authors.initials: V
authors.lastname: De Preter
authors.affiliation: Translational Research Center for Gastrointestinal Disorders (TARGID) and Leuven Food Science and Nutrition Research Centre (LFoRCe), University Hospital Gasthuisberg, KU Leuven, Leuven, Belgium.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Machiels
authors.affiliation: Translational Research Center for Gastrointestinal Disorders (TARGID) and Leuven Food Science and Nutrition Research Centre (LFoRCe), University Hospital Gasthuisberg, KU Leuven, Leuven, Belgium Department of Structural Biology, Research group of Bioinformatics and (Eco-)Systems Biology, VIB, Brussels, Belgium Microbiology Unit (MICR), Department of Applied Biological Sciences (DBIT), Vrije Universiteit Brussel, Brussels, Belgium.
authors.forename: Marie
authors.initials: M
authors.lastname: Joossens
authors.affiliation: Translational Research Center for Gastrointestinal Disorders (TARGID) and Leuven Food Science and Nutrition Research Centre (LFoRCe), University Hospital Gasthuisberg, KU Leuven, Leuven, Belgium.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Arijs
authors.affiliation: Department of Clinical and Experimental Endocrinology, Subdivision Clinical Nutrition, University Hospital Gasthuisberg, KULeuven, Leuven, Belgium.
authors.forename: Christophe
authors.initials: C
authors.lastname: Matthys
authors.affiliation: Translational Research Center for Gastrointestinal Disorders (TARGID) and Leuven Food Science and Nutrition Research Centre (LFoRCe), University Hospital Gasthuisberg, KU Leuven, Leuven, Belgium.
authors.forename: Severine
authors.initials: S
authors.lastname: Vermeire
authors.affiliation: Translational Research Center for Gastrointestinal Disorders (TARGID) and Leuven Food Science and Nutrition Research Centre (LFoRCe), University Hospital Gasthuisberg, KU Leuven, Leuven, Belgium.
authors.forename: Paul
authors.initials: P
authors.lastname: Rutgeerts
authors.affiliation: Translational Research Center for Gastrointestinal Disorders (TARGID) and Leuven Food Science and Nutrition Research Centre (LFoRCe), University Hospital Gasthuisberg, KU Leuven, Leuven, Belgium.
authors.forename: Kristin
authors.initials: K
authors.lastname: Verbeke
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002208:Caproates / Q000032:analysis; D002210:Caprylates / Q000032:analysis; D016022:Case-Control Studies; D003093:Colitis, Ulcerative / Q000378:metabolism; D003424:Crohn Disease / Q000378:metabolism; D005227:Fatty Acids / Q000032:analysis*; D005243:Feces / Q000737:chemistry*; D005260:Female; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000175:diagnosis / Q000378:metabolism*; D008297:Male; D064307:Microbiota; D008875:Middle Aged; D019449:Pouchitis / Q000378:metabolism; D012680:Sensitivity and Specificity; D014631:Valerates / Q000032:analysis; D055815:Young Adult
chemical_list: D002208:Caproates; D002210:Caprylates; D005227:Fatty Acids; D014631:Valerates; C037652:hexanoic acid; C031492:octanoic acid
keywords: COLONIC FERMENTATION; COLONIC MICROFLORA; CROHN'S DISEASE; ULCERATIVE COLITIS