title: Colonisation by Faecalibacterium prausnitzii and maintenance of clinical remission in patients with ulcerative colitis.
abstract: BACKGROUND
  Although incrimination of the intestinal microbiota in the pathogenesis of IBD is widely accepted, few data are available about the role of specific bacteria. Potentially, Faecalibacterium prausnitzii, bacteria with anti-inflammatory properties, might be deficient in ulcerative colitis (UC).
  
  
  OBJECTIVE
  To quantify F. prausnitzii in the faecal microbiota of UC patients in remission and determine its relationship with relapse.
  
  
  METHODS
  A cross-sectional study included 116 UC patients in remission, 29 first-degree relatives and 31 healthy controls. A subset of eighteen patients, recruited during the first month of remission, underwent a 1-year follow-up. Total bacteria and F. prausnitzii were measured by quantitative Real Time PCR (qPCR, copies/g). Calprotectin was determined as inflammatory index (μg/g).
  
  
  RESULTS
  We found that F. prausnitzii was reduced in patients (median, IQR: 1.4 × 10⁸ , 5.1 × 10⁷-4.5 × 10⁸) and relatives (1.7 × 10⁸, 9.3 × 10⁷-5.1 × 10⁸) vs. controls (6.5 × 10⁸, 3.7 × 10⁸-1.6 × 10⁹, P < 0.0001). Moreover, low counts of F. prausnitzii were associated with less than 12 months of remission (8.0 × 10⁷, 2.0 × 10⁷-3.5 × 10⁸ vs. 2.1 × 10⁸, 1.0 × 10⁸-7.9 × 10⁸, P < 0.001) and more than 1 relapse/year (8.0 × 10⁷, 3.2 × 10⁷-3.8 × 10⁸ vs. 1.9 × 10⁸, 6.8 × 10⁷-6.0 × 10⁸, P < 0.01). When patients were followed up, F. prausnitzii increased steadily until reaching similar levels to those of controls if remission persisted (2.9 × 10⁸, 9.3 × 10⁶-1.2 × 10⁹; calprotectin: 76, 19-212), whereas it remained low if patients relapsed (2.2 × 10⁸, 1.4 × 10⁶-3.3 × 10⁸; calprotectin: 1760, 844-3662 P < 0.05 vs. controls).
  
  
  CONCLUSIONS
  Defective gut colonisation by F. prausnitzii occurred in UC patients during remission and in their unaffected relatives. The recovery of the F. prausnitzii population after relapse is associated with maintenance of clinical remission.
authors.affiliation: Department of Gastroenterology, Digestive System Research Unit, Institut de Recerca Vall d'Hebron, University Hospital Vall d'Hebron, Universitat Autònoma de Barcelona, Ciberehd, Barcelona, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Varela
authors.forename: C
authors.initials: C
authors.lastname: Manichanh
authors.forename: M
authors.initials: M
authors.lastname: Gallart
authors.forename: A
authors.initials: A
authors.lastname: Torrejón
authors.forename: N
authors.initials: N
authors.lastname: Borruel
authors.forename: F
authors.initials: F
authors.lastname: Casellas
authors.forename: F
authors.initials: F
authors.lastname: Guarner
authors.forename: M
authors.initials: M
authors.lastname: Antolin
mesh_terms: D000328:Adult; D003093:Colitis, Ulcerative / Q000382:microbiology*; D003430:Cross-Sectional Studies; D005243:Feces / Q000382:microbiology*; D005260:Female; D006094:Gram-Positive Bacteria / Q000302:isolation & purification*; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology*; D006801:Humans; D039841:Leukocyte L1 Antigen Complex / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010375:Pedigree; D060888:Real-Time Polymerase Chain Reaction; D012008:Recurrence; D045857:Ruminococcus / Q000302:isolation & purification*; D055815:Young Adult
chemical_list: D039841:Leukocyte L1 Antigen Complex