title: Mucosal Barrier Depletion and Loss of Bacterial Diversity are Primary Abnormalities in Paediatric Ulcerative Colitis.
abstract: OBJECTIVE
  Ulcerative colitis [UC] is associated with colonic mucosa barrier defects and bacterial dysbiosis, but these features may simply be the result of inflammation. Therefore, we sought to assess whether these features are inherently abrogated in the terminal ileum [TI] of UC patients, where inflammation is absent.
  
  
  METHODS
  TI biopsies from paediatric inflammatory bowel disease [IBD] subsets [Crohn's disease [CD; n = 13] and UC [n = 10]], and non-IBD disease controls [n = 12] were histologically graded, and alcian blue/periodic acid-Schiff stained biopsies were quantified. The mucosal barrier was assessed for mucin [MUC2], immunoglobulin [Ig]A, IgG, and total bacteria (fluorescence in-situ hybridisation [FISH probe EUB338]) by immunofluorescence. The regulation of mucin secretion was investigated by NLRP6 gene expression and immunofluorescence. The composition of the active mucosa-associated microbiota was explored by sequencing the 16S rRNA amplicon generated from total RNA.
  
  
  RESULTS
  Despite the absence of ileitis, UC patients displayed ileal barrier depletion illustrated by reductions in mucin-containing goblet cells and mucin production and altered epithelial NLRP6 expression. In both CD patients with ileitis and UC patients with normal histology, bacteria coated with IgA and IgG penetrated the TI mucin layer. Biopsy 16S rRNA sequencing revealed a reduction in α-diversity by three methods [Shannon, Simpson, and Equitability indices] between UC and non-IBD paediatric patients.
  
  
  CONCLUSIONS
  These findings suggest an underlying defect in the UC-afflicted intestinal tract even in the absence of inflammation, implicating barrier and microbial changes as primary abnormalities in UC that may play a causative role in disease development.
authors.affiliation: Centre of Excellence for Gastrointestinal Inflammation and Immunity Research, University of Alberta, Edmonton, Canada Department of Pediatrics, University of Alberta, Edmonton, AB, Canada.
authors.forename: Misagh
authors.initials: M
authors.lastname: Alipour
authors.affiliation: Centre of Excellence for Gastrointestinal Inflammation and Immunity Research, University of Alberta, Edmonton, Canada Department of Pediatrics, University of Alberta, Edmonton, AB, Canada.
authors.forename: Deenaz
authors.initials: D
authors.lastname: Zaidi
authors.affiliation: Centre of Excellence for Gastrointestinal Inflammation and Immunity Research, University of Alberta, Edmonton, Canada Department of Medicine, University of Alberta, Edmonton, AB, Canada.
authors.forename: Rosica
authors.initials: R
authors.lastname: Valcheva
authors.affiliation: Centre of Excellence for Gastrointestinal Inflammation and Immunity Research, University of Alberta, Edmonton, Canada Department of Medicine, University of Alberta, Edmonton, AB, Canada.
authors.forename: Juan
authors.initials: J
authors.lastname: Jovel
authors.affiliation: Department of Agriculture, Food, and Nutritional Science, University of Alberta, Edmonton, AB, Canada.
authors.forename: Inés
authors.initials: I
authors.lastname: Martínez
authors.affiliation: Department of Pediatrics, University of Alberta, Edmonton, AB, Canada Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB, Canada.
authors.forename: Consolato
authors.initials: C
authors.lastname: Sergi
authors.affiliation: Centre of Excellence for Gastrointestinal Inflammation and Immunity Research, University of Alberta, Edmonton, Canada Department of Agriculture, Food, and Nutritional Science, University of Alberta, Edmonton, AB, Canada Department of Biological Sciences, University of Alberta, Edmonton, Canada.
authors.forename: Jens
authors.initials: J
authors.lastname: Walter
authors.affiliation: Centre of Excellence for Gastrointestinal Inflammation and Immunity Research, University of Alberta, Edmonton, Canada Department of Medicine, University of Alberta, Edmonton, AB, Canada.
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Mason
authors.affiliation: Centre of Excellence for Gastrointestinal Inflammation and Immunity Research, University of Alberta, Edmonton, Canada Department of Medicine, University of Alberta, Edmonton, AB, Canada Department of Biological Sciences, University of Alberta, Edmonton, Canada Beijing Genomics Institute-Shenzhen, Beishan Industrial Zone, Yantian District, Shenzhen, China.
authors.forename: Gane Ka-Shu
authors.initials: GK
authors.lastname: Wong
authors.affiliation: Centre of Excellence for Gastrointestinal Inflammation and Immunity Research, University of Alberta, Edmonton, Canada Department of Medicine, University of Alberta, Edmonton, AB, Canada.
authors.forename: Levinus A
authors.initials: LA
authors.lastname: Dieleman
authors.affiliation: Department of Pediatrics, University of Alberta, Edmonton, AB, Canada.
authors.forename: Matthew W
authors.initials: MW
authors.lastname: Carroll
authors.affiliation: Department of Pediatrics, University of Alberta, Edmonton, AB, Canada.
authors.forename: Hien Q
authors.initials: HQ
authors.lastname: Huynh
authors.affiliation: Centre of Excellence for Gastrointestinal Inflammation and Immunity Research, University of Alberta, Edmonton, Canada Department of Pediatrics, University of Alberta, Edmonton, AB, Canada wine@ualberta.ca.
authors.forename: Eytan
authors.initials: E
authors.lastname: Wine
mesh_terms: D000293:Adolescent; D001706:Biopsy; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D003093:Colitis, Ulcerative / Q000382:microbiology / Q000473:pathology*; D003424:Crohn Disease / Q000382:microbiology / Q000473:pathology; D000069196:Gastrointestinal Microbiome / Q000235:genetics; D006801:Humans; D007082:Ileum / Q000382:microbiology / Q000473:pathology; D017404:In Situ Hybridization, Fluorescence; D007413:Intestinal Mucosa / Q000473:pathology*; D008297:Male; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D012336:RNA, Ribosomal, 16S
keywords: Ulcerative colitis; mucin; mucosal barrier