Evaluation of leukotriene biosynthetic capacity in lung tissues from horses with recurrent airway obstruction.
OBJECTIVE
To evaluate leukotriene (LT) biosynthetic capacity in lung tissue from healthy horses and horses with recurrent airway obstruction (RAO).


METHODS
Lung parenchyma and airway specimens from 8 RAO-affected and 5 healthy horses.


METHODS
Horses were stabled for > or = 72 hours. Blood was drawn before euthanasia, after which lung specimens were collected. Tissue strips from small airways and parenchyma were incubated in organ baths with the precursor LTA4 or stimulated with calcium ionophore A23187 or the tripeptide N-formyl-Met-Leu-Phe (fMLP), with or without exogenous arachidonic acid, in the presence of isolated blood neutrophils.


RESULTS
Stabling induced typical clinical signs of airway obstruction in RAO-affected horses but not control horses. When lung parenchyma or airway specimens from both groups of horses were incubated with calcium ionophore, with or without arachidonic acid, they did not form LT. In contrast, addition of LTA4 to both tissues resulted in conversion to LTB4, although concentrations of LTC4 were negligible in airways and parenchymal strips from healthy and RAO-affected horses. Incubation of airway and parenchymal strips with suspensions of autologous neutrophils did not influence formation of LT stimulated by calcium ionophore or fMLP, with or without exogenous arachidonic acid.


CONCLUSIONS
Results suggest that lung parenchyma and airway tissues themselves are not of substantial importance for LT formation in the lungs, although these tissues possessed some LTA4 hydrolase activity, enabling LTB4 formation. It may be speculated that LTB4 originates primarily from neutrophils and may play a role in the inflammatory events of RAO.
Lindberg
Asa
A
Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
Näsman-Glaser
Barbro
B
Lindgren
Jan Ake
JA
Robinson
N Edward
NE
D000402:Airway Obstruction / Q000276:immunology / Q000378:metabolism / Q000662:veterinary*; D000818:Animals; D016718:Arachidonic Acid / Q000276:immunology; D000001:Calcimycin / Q000276:immunology; D005260:Female; D006734:Horse Diseases / Q000276:immunology / Q000378:metabolism*; D006736:Horses; D066298:In Vitro Techniques; D007476:Ionophores / Q000276:immunology; D015289:Leukotrienes / Q000096:biosynthesis* / Q000276:immunology; D008168:Lung / Q000276:immunology / Q000378:metabolism*; D008297:Male; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000276:immunology; D009504:Neutrophils / Q000276:immunology
D007476:Ionophores; D015289:Leukotrienes; D016718:Arachidonic Acid; D000001:Calcimycin; D009240:N-Formylmethionine Leucyl-Phenylalanine