title: House dust mite-induced calcium signaling instigates epithelial barrier dysfunction and CCL20 production.
abstract: BACKGROUND
  House dust mite (HDM) affects the immunological and physical barrier function of airway epithelium, leading to allergic sensitization, airway remodeling, and eosinophilic inflammation in mouse models, although the mechanisms are still largely unknown.
  
  
  OBJECTIVE
  Given the implications for adenosine triphosphate (ATP)-dependent Ca(2+) signaling in allergic sensitization in mice, we sought to determine the role of intracellular Ca(2+) concentration ([Ca(2+)](i)) in HDM-induced barrier dysfunction and pro-inflammatory activity of bronchial epithelium.
  
  
  METHODS
  We investigated the effect of HDM on accumulation of [Ca(2+)](i) levels, barrier function, and CCL20 release in human bronchial epithelial 16HBE cells and primary bronchial epithelial cells (PBECs) from healthy subjects and asthma patients. Involvement of ATP-dependent activation of purinergic receptors and downstream Ca(2+) influx was studied, using the ATP hydrolyzing agent apyrase, the purinergic receptor agonist PPADS, the calcium chelator BAPTA-AM, and calpain inhibitors.
  
  
  RESULTS
  Asthma PBECs were more susceptible to HDM-induced barrier dysfunction, CCL20 secretion, and Ca(2+) influx than healthy PBECs. Furthermore, we show that the HDM-induced increase in CCL20 in PBECs and 16HBE cells and the HDM-induced barrier dysfunction in 16HBE cells are dependent on [Ca(2+)](i) accumulation. Additionally, we demonstrate that [Ca(2+)](i) accumulation is initiated partly through the activation of purinergic receptors, which contributes to HDM-induced epithelial barrier dysfunction by disruption of cell-cell contacts, but not CCL20 secretion.
  
  
  CONCLUSIONS
  Our data show for the first time that Ca(2+) signaling plays a crucial role in barrier dysfunction and the pro-inflammatory response of bronchial epithelium upon HDM exposure and may thus have important implications for the development of allergic asthma.
authors.affiliation: Department of Pathology and Medical Biology, Laboratory of Allergology and Pulmonary Diseases, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands; GRIAC Research Institute, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
authors.forename: S
authors.initials: S
authors.lastname: Post
authors.forename: M C
authors.initials: MC
authors.lastname: Nawijn
authors.forename: M R
authors.initials: MR
authors.lastname: Jonker
authors.forename: N
authors.initials: N
authors.lastname: Kliphuis
authors.forename: M
authors.initials: M
authors.lastname: van den Berge
authors.forename: A J M
authors.initials: AJ
authors.lastname: van Oosterhout
authors.forename: I H
authors.initials: IH
authors.lastname: Heijink
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000328:Adult; D000818:Animals; D001249:Asthma / Q000276:immunology / Q000503:physiopathology; D015820:Cadherins / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling; D016022:Case-Control Studies; D002460:Cell Line; D054418:Chemokine CCL20 / Q000096:biosynthesis*; D005260:Female; D006801:Humans; D008297:Male; D021381:Protein Transport; D039981:Pyroglyphidae / Q000276:immunology*; D011983:Receptors, Purinergic / Q000378:metabolism; D020545:Respiratory Mucosa / Q000276:immunology* / Q000378:metabolism* / Q000503:physiopathology; D055815:Young Adult
chemical_list: D015820:Cadherins; D054418:Chemokine CCL20; D011983:Receptors, Purinergic; D000255:Adenosine Triphosphate; D002118:Calcium
keywords: allergens; asthma; bronchial epithelium