Experimental induction of recurrent airway obstruction with inhaled fungal spores, lipopolysaccharide, and silica microspheres in horses.
OBJECTIVE
To evaluate experimental induction of recurrent airway obstruction (RAO) with inhaled fungal spores, lipopolysaccharide, and silica microspheres in horses.


METHODS
7 horses with and 3 horses without a history of RAO.


METHODS
RAO-susceptible horses ranged in age from 17 to approximately 30 years, and control horses ranged in age from 7 to approximately 15 years. Pure mold cultures were derived from repeated culture of hay and identified via gene amplification and sequencing. Pulmonary function testing and bronchoalveolar lavage were performed before and after nebulization with a suspension of spores derived from 3 fungi, lipopolysaccharide, and 1-microm silica microspheres in all horses. This was followed by a 4-month washout period and a further pulmonary function test followed by saline (0.9% NaCl) solution challenge and bronchoalveolar lavage.


RESULTS
Lichtheimia corymbifera, Aspergillus fumigatus, and Eurotium amstelodami were consistently identified in cultures of moldy hay. Nebulization with fungal spores, lipopolysaccharide, and microspheres induced significant increases in pleural pressure in RAO-susceptible but not control horses. Airway neutrophilia developed in both groups of horses with exposure to challenge material but more severely in RAO-susceptible horses.


CONCLUSIONS
Results indicated that inhalation of fungal spores in combination with lipopolysaccharide and silica microspheres can induce disease exacerbation in susceptible horses and may thus be a useful model for future standardized studies of RAO in horses.
Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada.
Janet
J
Beeler-Marfisi
Mary Ellen
ME
Clark
Xin
X
Wen
William
W
Sears
Leslie
L
Huber
Cameron
C
Ackerley
Laurent
L
Viel
Dorothee
D
Bienzle
D000402:Airway Obstruction / Q000209:etiology / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry / Q000166:cytology / Q000382:microbiology; D006734:Horse Diseases / Q000209:etiology* / Q000276:immunology / Q000382:microbiology; D006736:Horses; D008070:Lipopolysaccharides / Q000008:administration & dosage / Q000276:immunology; D016676:Macrophages, Alveolar / Q000648:ultrastructure; D008855:Microscopy, Electron, Scanning / Q000662:veterinary; D010865:Pilot Projects; D012129:Respiratory Function Tests / Q000662:veterinary; D012822:Silicon Dioxide / Q000008:administration & dosage / Q000276:immunology; D013172:Spores, Fungal / Q000276:immunology
D008070:Lipopolysaccharides; D012822:Silicon Dioxide