title: A decrease of the butyrate-producing species Roseburia hominis and Faecalibacterium prausnitzii defines dysbiosis in patients with ulcerative colitis.
abstract: OBJECTIVE
  Bacteria play an important role in the onset and perpetuation of intestinal inflammation in inflammatory bowel disease (IBD). Unlike in Crohn's disease (CD), in which dysbiosis has been better characterised, in ulcerative colitis (UC), only small cohorts have been studied and showed conflicting data. Therefore, we evaluated in a large cohort if the microbial signature described in CD is also present in UC, and if we could characterise predominant dysbiosis in UC. To assess the functional impact of dysbiosis, we quantified the bacterial metabolites.
  
  
  METHODS
  The predominant microbiota from 127 UC patients and 87 age and sex-matched controls was analysed using denaturing gradient gel electrophoresis (DGGE) analysis. Differences were quantitatively validated using real-time PCR. Metabolites were quantified using gas chromatography-mass spectrometry.
  
  
  RESULTS
  Based on DGGE analysis, the microbial signature previously described in CD was not present in UC. Real-time PCR analysis revealed a lower abundance of Roseburia hominis (p<0.0001) and Faecalibacterium prausnitzii (p<0.0001) in UC patients compared to controls. Both species showed an inverse correlation with disease activity. Short-chain fatty acids (SCFA) were reduced in UC patients (p=0.014), but no direct correlation between SCFA and the identified bacteria was found.
  
  
  CONCLUSIONS
  The composition of the fecal microbiota of UC patients differs from that of healthy individuals: we found a reduction in R hominis and F prausnitzii, both well-known butyrate-producing bacteria of the Firmicutes phylum. These results underscore the importance of dysbiosis in IBD but suggest that different bacterial species contribute to the pathogenesis of UC and CD.
authors.affiliation: Translational Research Center for Gastrointestinal Disorders (TARGID), University Hospital Gasthuisberg, KU Leuven, Leuven, Belgium.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Machiels
authors.affiliation: Department of Structural Biology, VIB-Vrije Universiteit Brussel, Brussels, Belgium 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), University Hospital Gasthuisberg, KU Leuven, Leuven, Belgium.
authors.forename: João
authors.initials: J
authors.lastname: Sabino
authors.affiliation: Translational Research Center for Gastrointestinal Disorders (TARGID), 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), University Hospital Gasthuisberg, KU Leuven, Leuven, Belgium.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Arijs
authors.affiliation: Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
authors.forename: Venessa
authors.initials: V
authors.lastname: Eeckhaut
authors.affiliation: Translational Research Center for Gastrointestinal Disorders (TARGID), University Hospital Gasthuisberg, KU Leuven, Leuven, Belgium.
authors.forename: Vera
authors.initials: V
authors.lastname: Ballet
authors.affiliation: Translational Research Center for Gastrointestinal Disorders (TARGID), University Hospital Gasthuisberg, KU Leuven, Leuven, Belgium.
authors.forename: Karolien
authors.initials: K
authors.lastname: Claes
authors.affiliation: Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
authors.forename: Filip
authors.initials: F
authors.lastname: Van Immerseel
authors.affiliation: Translational Research Center for Gastrointestinal Disorders (TARGID), Leuven Food Science and Nutrition Research Centre (LFoRCe), University Hospital Gasthuisberg, KU Leuven, Leuven, Belgium.
authors.forename: Kristin
authors.initials: K
authors.lastname: Verbeke
authors.affiliation: Translational Research Center for Gastrointestinal Disorders (TARGID), University Hospital Gasthuisberg, KU Leuven, Leuven, Belgium.
authors.forename: Marc
authors.initials: M
authors.lastname: Ferrante
authors.affiliation: Department of Clinical Microbiology, University Hospital Gasthuisberg, KU Leuven, Leuven, Belgium.
authors.forename: Jan
authors.initials: J
authors.lastname: Verhaegen
authors.affiliation: Translational Research Center for Gastrointestinal Disorders (TARGID), 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), University Hospital Gasthuisberg, KU Leuven, Leuven, Belgium.
authors.forename: Séverine
authors.initials: S
authors.lastname: Vermeire
mesh_terms: D000328:Adult; D058491:Bacterial Load; D020148:Butyric Acid / Q000032:analysis; D016022:Case-Control Studies; D003093:Colitis, Ulcerative / Q000382:microbiology*; D058645:Denaturing Gradient Gel Electrophoresis; D064806:Dysbiosis / Q000382:microbiology*; D005243:Feces / Q000737:chemistry* / Q000382:microbiology*; D005260:Female; D016965:Gram-Negative Anaerobic Straight, Curved, and Helical Rods / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D006801:Humans; D019344:Lactic Acid / Q000032:analysis; D008297:Male; D008875:Middle Aged; D011422:Propionates / Q000032:analysis; D060888:Real-Time Polymerase Chain Reaction; D012720:Severity of Illness Index
chemical_list: D011422:Propionates; D020148:Butyric Acid; D019344:Lactic Acid; C029658:propionic acid
keywords: INTESTINAL BACTERIA; ULCERATIVE COLITIS