title: The activity and expression of chitinase in the equine lung and its activity in normal horses and animals with recurrent airway obstruction.
abstract: Recurrent airway obstruction (RAO) is a chronic inflammatory condition in equine lung, which may share a common immunological basis with human asthma, in which dysregulated Th2 responses occur. Mammals express chitinases and chitinase-like proteins, two of which are active enzymes, chitotriosidase and acidic mammalian chitinase (AMCase). Both enzymes are upregulated in a range of inflammatory conditions, including asthma. We investigated the activity of chitinase in bronchoalveolar lavage fluid from horses with and without RAO in response to organic dust challenges. No significant differences were found in activity, although in one study RAO animals had elevated chitinase activity that fell short of statistical significance. The pH optimum and pH lability of the activity was consistent with the presence of chitotriosidase. RT-PCR amplification of the mRNA encoding chitotriosidase and AMCase in normal equine lung showed that chitotriosidase, but not AMCase, is expressed in trachea, bronchi, and peripheral lung tissue. The gene for chitotriosidase was identified from the Equus caballus (horse) genome 1.1 database and its similarity to the same genes from other species was determined. The results of this study indicate that the involvement of chitotriosidase in RAO is uncertain.
authors.affiliation: Veterinary Sciences Centre, School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: Colm J
authors.initials: CJ
authors.lastname: Reid
authors.forename: Laura
authors.initials: L
authors.lastname: Thompson
authors.forename: Samantha
authors.initials: S
authors.lastname: Donnelly
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Deaton
authors.forename: David J
authors.initials: DJ
authors.lastname: Marlin
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Carrington
authors.forename: Jane A
authors.initials: JA
authors.lastname: Irwin
mesh_terms: D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry; D002688:Chitinases / Q000235:genetics / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D006596:Hexosaminidases / Q000235:genetics / Q000378:metabolism*; D006734:Horse Diseases / Q000201:enzymology*; D006736:Horses; D006863:Hydrogen-Ion Concentration; D008168:Lung / Q000201:enzymology*; D029424:Pulmonary Disease, Chronic Obstructive / Q000201:enzymology / Q000235:genetics / Q000662:veterinary*; D012313:RNA
chemical_list: D012313:RNA; D006596:Hexosaminidases; C086400:chitotriosidase; D002688:Chitinases