The effect of adding oral dexamethasone to feed alterations on the airway cell inflammatory gene expression in stabled horses affected with recurrent airway obstruction.
BACKGROUND
Chemokine expression in airway epithelium and bronchoalveolar lavage fluid (BALF) cells of horses with recurrent airway obstruction (RAO) is increased.


OBJECTIVE
For RAO-affected horses that are stabled and fed a pelleted ration, the addition of oral dexamethasone further improves pulmonary function and reduces inflammatory gene expression in pulmonary cells.


METHODS
Twelve RAO-affected horses.


METHODS
In a randomized cross-over experiment, the effect of feeding pellets in lieu of hay to stabled, RAO-affected horses was compared with the effect of feeding pellets and administering a 21-day decreasing dose regimen of oral dexamethasone on the expression (by kinetic polymerase chain reaction) of interleukin-8 (IL-8), chemokine (C-X-C motif) ligand 2 (CXCL2), IL-1beta, IL-6, and beta-actin in the BALF cells and of IL-8, CXCL2, 2 IL-1 receptor (IL-1R2), Toll-like receptor 4 (TLR4), and glyceraldehyde 3-phosphate dehydrogenase in the bronchial epithelium 2 days after the final dose.


RESULTS
Both treatments reduced airway neutrophilia and breathing efforts but the addition of dexamethasone was associated with fewer treatment failures. Compared with feed changes alone, dexamethasone administration further reduced the expression of IL-8, CXCL2, and IL-1beta in the BALF cells 3.3-, 2.5-, and 4.7-fold, respectively. In the airway epithelium, both treatments were equally efficacious in reducing the expression of IL-8 and CXCL2 expression relative to pretreatment values, but either treatment failed to alter the expression of IL-1R2 and TLR4.


CONCLUSIONS
For a rapid and consistent improvement in pulmonary function and a reduction in inflammatory gene expression of the BALF cells, a decreasing dose of oral dexamethasone in combination with feed alterations is more efficacious for horses that must remain stabled.
DeLuca
L
L
Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA.
Erb
H N
HN
Young
J C
JC
Perkins
G A
GA
Ainsworth
D M
DM
D000821:Animal Feed / Q000009:adverse effects; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D018925:Chemokines / Q000096:biosynthesis / Q000235:genetics; D018592:Cross-Over Studies; D003907:Dexamethasone / Q000494:pharmacology* / Q000627:therapeutic use; D004847:Epithelial Cells / Q000378:metabolism; D005260:Female; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects*; D006734:Horse Diseases / Q000188:drug therapy*; D006736:Horses; D006799:Housing, Animal; D007249:Inflammation / Q000188:drug therapy / Q000662:veterinary; D008173:Lung Diseases, Obstructive / Q000188:drug therapy / Q000662:veterinary*; D008297:Male
D000893:Anti-Inflammatory Agents; D018925:Chemokines; D003907:Dexamethasone