title: Enteric glia regulate intestinal barrier function and inflammation via release of S-nitrosoglutathione.
abstract: OBJECTIVE
  Barrier functions across epithelia and endothelia are essential for homeostatic tissue regulation. Astroglia interact with cerebral endothelia to maintain the blood-brain barrier. Whether similar interactions between astrocyte-like enteric glia and epithelia regulate intestinal barrier function is not known.
  
  
  METHODS
  Fluorescent permeability markers were used to measure intestinal barrier function in vivo after conditional ablation of enteric glia in transgenic mice. Enteric glial cell regulation of epithelial barrier integrity then was modeled in vitro using coculture. Glial-derived barrier-inducing factors were characterized using size-exclusion chromatography and mass spectrometry. Epithelial barrier integrity was assessed by transepithelial resistance readings and by quantitative measurement of tight-junction-associated protein expression by quantitative polymerase chain reaction and Western blot.
  
  
  RESULTS
  We show that ablation of enteric glial cells in transgenic mice causes intestinal mucosal barrier dysfunction, resulting in inflammation. Glial-derived s-nitrosoglutathione (GSNO) was identified as a potent inducer of mucosal barrier function in vitro and in vivo and of attenuated tissue inflammation after ablation of enteric glia in transgenic mice. GSNO regulation of mucosal barrier function was associated directly with an increased expression of perijunctional F-actin and tight-junction-associated proteins zonula occludens-1 and occludin. GSNO also significantly restored mucosal barrier function in colonic biopsy specimens from patients with Crohn's disease, a well-described inflammatory permeability disorder associated with enteric glial-cell disruption.
  
  
  CONCLUSIONS
  Enteric glia therefore share the ability of astrocytes to regulate tight-junction integrity, and cellular interactions comparable with those maintaining blood-brain barrier function also regulate epithelial permeability at mucosal surfaces.
authors.affiliation: Division of Gastroenterology, The University of Texas Medical Branch, Galveston, Texas, USA. tcsavidg@utmb.edu
authors.forename: Tor C
authors.initials: TC
authors.lastname: Savidge
authors.forename: Paul
authors.initials: P
authors.lastname: Newman
authors.forename: Charalabos
authors.initials: C
authors.lastname: Pothoulakis
authors.forename: Anne
authors.initials: A
authors.lastname: Ruhl
authors.forename: Michel
authors.initials: M
authors.lastname: Neunlist
authors.forename: Arnaud
authors.initials: A
authors.lastname: Bourreille
authors.forename: Roger
authors.initials: R
authors.lastname: Hurst
authors.forename: Michael V
authors.initials: MV
authors.lastname: Sofroniew
mesh_terms: D000199:Actins / Q000235:genetics; D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D001253:Astrocytes / Q000502:physiology*; D001706:Biopsy; D015153:Blotting, Western; D002478:Cells, Cultured; D003092:Colitis / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D003106:Colon / Q000378:metabolism / Q000473:pathology; D003911:Dextrans / Q000493:pharmacokinetics; D004285:Dogs; D004338:Drug Combinations; D017615:Enteric Nervous System / Q000502:physiology* / Q000601:surgery; D004797:Enzyme-Linked Immunosorbent Assay; D004848:Epithelium / Q000378:metabolism; D004958:Estradiol / Q000031:analogs & derivatives; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D015870:Gene Expression; D006801:Humans; D007413:Intestinal Mucosa / Q000166:cytology / Q000294:innervation / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D008875:Middle Aged; D009640:Norethindrone; D062793:Occludin; D010539:Permeability; D016133:Polymerase Chain Reaction; D012313:RNA / Q000235:genetics; D051381:Rats; D026422:S-Nitrosoglutathione / Q000378:metabolism*; D013739:Testosterone / Q000031:analogs & derivatives; D062827:Zonula Occludens-2 Protein
chemical_list: D000199:Actins; D003911:Dextrans; D004338:Drug Combinations; D008565:Membrane Proteins; C568985:OCLN protein, human; D062793:Occludin; C568986:Ocln protein, mouse; C568987:Ocln protein, rat; C569046:TJP2 protein, human; C569047:Tjp2 protein, mouse; D062827:Zonula Occludens-2 Protein; C023715:estradiol, norethisterone, testosterone drug combination; C015219:fluorescein isothiocyanate dextran; D013739:Testosterone; D004958:Estradiol; D026422:S-Nitrosoglutathione; D012313:RNA; D016650:Fluorescein-5-isothiocyanate; D009640:Norethindrone