A CONSORT-guided, randomized controlled clinical trial of nebulized administration of dexamethasone and saline on lower airway cytokine mRNA expression in horses with moderate asthma.
Authors: Bond Stephanie, Léguillette Renaud
Journal: Journal of veterinary internal medicine
Summary
# Editorial Summary: Nebulized Dexamethasone and Lower Airway Cytokine Expression in Equine Asthma Bond and Léguillette investigated whether nebulized dexamethasone could modulate inflammatory cytokine expression in horses with moderate asthma, a clinically relevant question given the widespread use of inhaled corticosteroids in equine respiratory management. In a prospective, randomized, blinded trial, 16 asthmatic horses and 4 healthy controls received either 15 mg nebulized dexamethasone once daily or saline placebo for 13 days whilst housed in a dusty environment; researchers measured mRNA expression of 12 inflammatory markers in bronchoalveolar lavage fluid using qPCR before and after treatment. Contrary to expectations, dexamethasone-treated horses showed significant *increases* in IL-5 (1.70-fold), IL-6 (1.71-fold), IL-17 (3.25-fold), IL-12 (1.66-fold), and TNF-α (1.94-fold), with only IL-23 suppressed (1.76-fold reduction); saline treatment produced no significant changes in any cytokine measured. Most notably, neither dexamethasone nor saline resulted in measurable improvements in inflammatory airway cytology, raising important questions about the therapeutic efficacy of nebulized corticosteroid monotherapy in naturally occurring equine asthma and suggesting that current dosing protocols or delivery mechanisms may require re-evaluation for clinical benefit.
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Practical Takeaways
- •Nebulized dexamethasone may paradoxically increase inflammatory cytokine expression in horses with moderate asthma, contrary to expected anti-inflammatory effects, suggesting this route and dose may not be effective for managing equine asthma
- •Current nebulized dexamethasone protocols do not improve the cytological inflammatory profile in horses with asthma, questioning their clinical utility in this patient population
- •Alternative treatment approaches or dosing regimens for nebulized corticosteroids should be investigated before recommending this therapy for equine asthma management
Key Findings
- •Nebulized dexamethasone (15 mg daily for 13 days) increased relative expression of pro-inflammatory cytokines IL-5 (1.70-fold), IL-6 (1.71-fold), IL-17 (3.25-fold), IL-12 (1.66-fold), and TNF-α (1.94-fold) in BAL fluid
- •Nebulized dexamethasone decreased IL-23 expression (1.76-fold reduction) compared to baseline
- •Saline control treatment produced no significant changes in cytokine mRNA expression
- •Neither dexamethasone nor saline treatment resulted in improvement in inflammatory airway cytology