title: Expression of toll-like receptor 2 mRNA in bronchial epithelial cells is not induced in RAO-affected horses.
abstract: BACKGROUND
  Airway inflammation in recurrent airway obstruction (RAO) is triggered by housing affected horses in stables.It has been suggested that RAO is an allergic condition, but innate immune mechanisms are also involved. Fungal products activate innate immune mechanisms through toll-like receptor 2 (TLR2). In human airway epithelium, TLR2 activation leads to interleukin (IL)-8 production. This pathway is negatively regulated by the zinc finger protein A20. This study was performed to enhance understanding of innate immune mechanisms in RAO.
  
  
  OBJECTIVE
  TLR2 and IL-8 mRNA are elevated in RAO during stabling compared with controls. A20 mRNA is negatively associated with the numbers of airway inflammatory cells.
  
  
  OBJECTIVE
  To determine TLR2, IL-8 and A20 mRNA expression in lungs of stabled and pastured RAO-affected and control horses.
  
  
  METHODS
  Airway obstruction and inflammatory cell counts in bronchoalveolar lavage were measured, and TLR2, IL-8 and A20 mRNA expression quantified by qRT-PCR in 6 RAO-affected and 6 control horses, during and after exposure to hay and straw.
  
  
  RESULTS
  Airway obstruction and neutrophils were increased in RAO-affected horses during stabling. While stabling increased IL-8, TLR2 and A20 mRNA were unaffected. TLR2 and A20 were significantly correlated (r = 0.83) and A20 mRNA was negatively associated with inflammatory cells.
  
  
  CONCLUSIONS
  Stabling does not lead to an increase in TLR2 expression. Other molecules or processes in the TLR2 cascade might be important in fungal-induced airway inflammation. Equine epithelial-derived A20 may be involved in modulation of airway inflammation.
authors.affiliation: Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan 48824, USA.
authors.forename: A
authors.initials: A
authors.lastname: Berndt
authors.forename: F J
authors.initials: FJ
authors.lastname: Derksen
authors.forename: P J
authors.initials: PJ
authors.lastname: Venta
authors.forename: W
authors.initials: W
authors.lastname: Karmaus
authors.forename: S
authors.initials: S
authors.lastname: Ewart
authors.forename: V
authors.initials: V
authors.lastname: Yuzbasiyan-Gurkan
authors.forename: N E
authors.initials: NE
authors.lastname: Robinson
mesh_terms: D000402:Airway Obstruction / Q000276:immunology / Q000503:physiopathology / Q000662:veterinary*; D000818:Animals; D001980:Bronchi / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D016022:Case-Control Studies; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology; D006734:Horse Diseases / Q000276:immunology / Q000503:physiopathology*; D006736:Horses; D006799:Housing, Animal; D007113:Immunity, Innate; D007249:Inflammation / Q000209:etiology / Q000276:immunology / Q000662:veterinary; D016209:Interleukin-8 / Q000096:biosynthesis / Q000235:genetics; D008297:Male; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051195:Toll-Like Receptor 2 / Q000235:genetics* / Q000378:metabolism
chemical_list: D016209:Interleukin-8; D009687:Nuclear Proteins; D012333:RNA, Messenger; D051195:Toll-Like Receptor 2