title: Organic dust exposure increases mast cell tryptase in bronchoalveolar lavage fluid and airway epithelium of heaves horses.
abstract: BACKGROUND
  Mast cell degranulation is believed to act as a key event in initiating and maintaining airway response to allergen challenge in human asthma. It is hypothesized that the mast cell may play a similar role in equine heaves, which shares many similarities with occupational dust-induced asthma.
  
  
  OBJECTIVE
  The aim of this study was to quantify the mast cell proteinase tryptase in bronchoalveolar lavage fluid (BALF) from control and heaves-susceptible horses and to investigate tryptase mRNA and protein expression in pulmonary mast cells.
  
  
  METHODS
  Equine BALF tryptase concentrations were determined by ELISA from control and heaves-susceptible horses pre and post 24 h hay/straw challenge (HSC). Tryptase mRNA and protein expression were investigated by quantitative PCR and immunohistochemistry in bronchial and bronchiolar tissue samples of control and heaves-susceptible horses.
  
  
  RESULTS
  Both control and heaves-susceptible horses had significantly increased BALF tryptase concentrations following HSC (P=0.003 and 0.034, respectively). Increased numbers of tryptase-expressing intra-epithelial mast cells were demonstrated in heaves horses, but not controls, following challenge (P=0.02). Bronchiolar tissue from heaves horses removed from challenge contained significantly lower tryptase transcripts than that from control horses (P=0.02).
  
  
  CONCLUSIONS
  Mast cell degranulation and tryptase release into the airways occur following HSC of control and heaves-susceptible horses. The greater number of mast cells available in the bronchiolar epithelium of heaves horses may be clinically significant in the pulmonary inflammatory response of heaves.
authors.affiliation: Department of Veterinary Clinical Sciences, Easter Bush Veterinary Centre, Royal (Dick) School of Veterinary Studies, Midlothian, UK. K.J.Dacre@massey.ac.nz
authors.forename: K J
authors.initials: KJ
authors.lastname: Dacre
authors.forename: B C
authors.initials: BC
authors.lastname: McGorum
authors.forename: D J
authors.initials: DJ
authors.lastname: Marlin
authors.forename: L R
authors.initials: LR
authors.lastname: Bartner
authors.forename: J K
authors.initials: JK
authors.lastname: Brown
authors.forename: D J
authors.initials: DJ
authors.lastname: Shaw
authors.forename: N E
authors.initials: NE
authors.lastname: Robinson
authors.forename: C
authors.initials: C
authors.lastname: Deaton
authors.forename: A D
authors.initials: AD
authors.lastname: Pemberton
mesh_terms: D000818:Animals; D001992:Bronchoalveolar Lavage Fluid; D016022:Case-Control Studies; D004391:Dust; D004848:Epithelium / Q000187:drug effects / Q000201:enzymology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006736:Horses / Q000378:metabolism*; D007150:Immunohistochemistry; D008407:Mast Cells / Q000187:drug effects / Q000201:enzymology*; D009930:Organic Chemicals / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics; D053802:Tryptases / Q000235:genetics / Q000378:metabolism*
chemical_list: D004391:Dust; D009930:Organic Chemicals; D012333:RNA, Messenger; D053802:Tryptases