title: Eosinophils express muscarinic receptors and corticotropin-releasing factor to disrupt the mucosal barrier in ulcerative colitis.
abstract: OBJECTIVE
  Altered intestinal barrier function has been implicated in the pathophysiology of ulcerative colitis (UC) in genetic, functional, and epidemiological studies. Mast cells and corticotropin-releasing factor (CRF) regulate the mucosal barrier in human colon. Because eosinophils are often increased in colon tissues of patients with UC, we assessed interactions among mast cells, CRF, and eosinophils in the mucosal barrier of these patients.
  
  
  METHODS
  Transmucosal fluxes of protein antigens (horseradish peroxidase) and paracellular markers ((51)Cr-EDTA, fluorescein isothiocyanate-dextran 4000) were studied in noninflamed, colonic mucosal biopsy samples collected from 26 patients with UC and 53 healthy volunteers (controls); samples were mounted in Ussing chambers. We also performed fluorescence and electron microscopy of human tissue samples, assessed isolated eosinophils, and performed mechanistic studies using in vitro cocultured eosinophils (15HL-60), mast cells (HMC-1), and a colonic epithelial cell line (T84).
  
  
  RESULTS
  Colon tissues from patients with UC had significant increases in permeability to protein antigens compared with controls. Permeability was blocked by atropine (a muscarinic receptor antagonist), α-helical CRF(9-41) (a CRF receptor antagonist), and lodoxamide (a mast-cell stabilizer). Eosinophils were increased in number in UC tissues (compared with controls), expressed the most M2 and M3 muscarinic receptors of any mucosal cell type, and had immunoreactivity to CRF. In coculture studies, carbachol activation of eosinophils caused production of CRF and activation of mast cells, which increased permeability of T84 epithelial cells to macromolecules.
  
  
  CONCLUSIONS
  We identified a neuroimmune intercellular circuit (from cholinergic nerves, via eosinophils to mast cells) that mediates colonic mucosal barrier dysfunction in patients with UC. This circuit might exacerbate mucosal inflammation.
authors.affiliation: Department of Clinical and Experimental Medicine, Division of Surgery, Linköping University, Sweden.
authors.forename: Conny
authors.initials: C
authors.lastname: Wallon
authors.forename: Mats
authors.initials: M
authors.lastname: Persborn
authors.forename: Maria
authors.initials: M
authors.lastname: Jönsson
authors.forename: Arthur
authors.initials: A
authors.lastname: Wang
authors.forename: Van
authors.initials: V
authors.lastname: Phan
authors.forename: Maria
authors.initials: M
authors.lastname: Lampinen
authors.forename: Maria
authors.initials: M
authors.lastname: Vicario
authors.forename: Javier
authors.initials: J
authors.lastname: Santos
authors.forename: Philip M
authors.initials: PM
authors.lastname: Sherman
authors.forename: Marie
authors.initials: M
authors.lastname: Carlson
authors.forename: Ann-Charlott
authors.initials: AC
authors.lastname: Ericson
authors.forename: Derek M
authors.initials: DM
authors.lastname: McKay
authors.forename: Johan D
authors.initials: JD
authors.lastname: Söderholm
mesh_terms: D001285:Atropine / Q000494:pharmacology; D001706:Biopsy; D002460:Cell Line; D003093:Colitis, Ulcerative / Q000378:metabolism* / Q000473:pathology; D003346:Corticotropin-Releasing Hormone / Q000096:biosynthesis* / Q000187:drug effects; D004804:Eosinophils / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D005434:Flow Cytometry; D006801:Humans; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D008407:Mast Cells / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D017348:Microscopy, Electron, Scanning Transmission; D018727:Muscarinic Antagonists / Q000494:pharmacology; D011976:Receptors, Muscarinic / Q000096:biosynthesis* / Q000187:drug effects
chemical_list: D018727:Muscarinic Antagonists; D011976:Receptors, Muscarinic; D001285:Atropine; D003346:Corticotropin-Releasing Hormone