title: Cholinergic receptor activation on epithelia protects against cytokine-induced barrier dysfunction.
abstract: OBJECTIVE
  Various types of cholinergic receptors are expressed on intestinal epithelia. Their function is not completely understood. We hypothesize that cholinergic receptor activation on epithelium may serve a protective function in cytokine-induced barrier dysfunction.
  
  
  METHODS
  The effect of cholinergic receptor activation on cellular barrier function in epithelial cells was assessed by measuring electrical impedance, and by determining para-cellular transport in transwell experiments. Cell lysates treated with cytokine and/or cholinergic agonists were analysed for cyto- and chemokine production, and tight junction (TJ) protein rearrangement was assessed. Primary colonic epithelial cells were isolated from surgically resected colon tissue of patients with inflammatory bowel disease.
  
  
  RESULTS
  IL-1β induced production of chemokines (CXCL-1, CXCL-10, IL-8, CCL-7) and led to a rearrangement of TJ proteins (occludin and ZO-1). This response was inhibited by pre-treatment with muscarinic, rather than nicotinic, acetylcholine receptor agonists. Treatment with IL-1β enhanced paracellular permeability (4kD dextran) and reduced impedance across the monolayer, which was counteracted by pre-incubation with acetylcholine, or muscarinic receptor agonist bethanechol. The protective effect of acetylcholine was antagonized by atropine, underscoring muscarinic receptor involvement. IL-1β induced transcription of myosin light chain kinase and phosphorylation of myosin light chain, and this cytokine-induced phosphorylation of MLC was inhibited by muscarinic receptor agonists. Furthermore, in epithelial cells from resection material of patients with Crohn's disease and ulcerative colitis, high expression of CXCL-8 was associated with a reduced choline acetyl transferase expression, suggesting an aberrant epithelial production of ACh in inflammatory context.
  
  
  CONCLUSIONS
  Acetylcholine acts on muscarinic receptors on epithelial cells to maintain epithelial barrier function under inflammatory conditions.
authors: Tytgat Institute for Liver and Intestinal Diseases, Amsterdam, the Netherlands.
authors: S
authors: S
authors: Dhawan
authors: I H
authors: IH
authors: Hiemstra
authors: C
authors: C
authors: Verseijden
authors: F W
authors: FW
authors: Hilbers
authors: A A
authors: AA
authors: Te Velde
authors: L E M
authors: LE
authors: Willemsen
authors: J
authors: J
authors: Stap
authors: J M
authors: JM
authors: den Haan
authors: W J
authors: WJ
authors: de Jonge
mesh_terms: D000818:Animals; D002460:Cell Line; D002470:Cell Survival; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D004847:Epithelial Cells / Q000166:cytology* / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D053583:Interleukin-1beta / Q000494:pharmacology; D051379:Mice; D062793:Occludin / Q000235:genetics / Q000378:metabolism; D011950:Receptors, Cholinergic / Q000235:genetics / Q000378:metabolism*; D011976:Receptors, Muscarinic / Q000235:genetics / Q000378:metabolism; D019108:Tight Junctions / Q000378:metabolism; D062826:Zonula Occludens-1 Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D016207:Cytokines; D053583:Interleukin-1beta; D062793:Occludin; D011950:Receptors, Cholinergic; D011976:Receptors, Muscarinic; D062826:Zonula Occludens-1 Protein
keywords: cholinergic receptors; epithelial permeability; interleukin-1 beta; myosin light chain; tight junction proteins