Effect of beclomethasone dipropionate and dexamethasone isonicotinate on lung function, bronchoalveolar lavage fluid cytology, and transcription factor expression in airways of horses with recurrent airway obstruction.
Authors: Couëtil Laurent L, Art Tatiana, de Moffarts Brieuc, Becker Martine, Mélotte Dorothée, Jaspar Fabrice, Bureau Fabrice, Lekeux Pierre
Journal: Journal of veterinary internal medicine
Summary
# Editorial Summary Glucocorticoid therapy remains a cornerstone of recurrent airway obstruction (RAO) management, though their precise mechanisms in equine airways remain incompletely understood. This 2006 crossover study compared inhaled beclomethasone dipropionate (500 µg twice daily for 10 days) with a single intramuscular injection of dexamethasone isonicotinate (0.06 mg/kg) and placebo in seven RAO-affected horses challenged with moldy hay, measuring pulmonary function, bronchoalveolar lavage cytology, and transcription factor activity (NF-κB and AP-1) in bronchial cells on days 1 and 10. Beclomethasone significantly improved lung function parameters compared with both placebo and dexamethasone treatments; however, neither glucocorticoid altered airway inflammatory cell populations or suppressed the DNA-binding activity of NF-κB and AP-1, the transcription factors conventionally thought to mediate their anti-inflammatory effects. These findings suggest that the clinical benefits of inhaled glucocorticoids in severe RAO may operate through mechanisms independent of these classical inflammatory pathways—potentially via alternative signalling cascades or local airway effects—rather than through generalised suppression of transcription factor activity. The superior efficacy of inhaled over systemic corticosteroids in this acute challenge model reinforces the importance of topical lung delivery for RAO management, whilst the disconnect between functional improvement and expected molecular markers warrants further investigation into glucocorticoid mechanisms in equine airways.
Read the full abstract on PubMed
Practical Takeaways
- •Inhaled beclomethasone appears more effective than systemic dexamethasone for improving lung function in horses with severe RAO, though the mechanism may not involve suppression of these specific transcription factors
- •The clinical benefits of inhaled glucocorticoids in RAO cannot be explained solely by reduction in airway inflammatory cells, suggesting alternative anti-inflammatory mechanisms are at work
- •Low-dose inhaled therapy may offer advantages over systemic injection for RAO management in practice, despite similar anti-inflammatory targets
Key Findings
- •Inhaled beclomethasone (500 µg q12h) significantly improved pulmonary function in RAO-affected horses compared to placebo and dexamethasone treatments
- •Dexamethasone (0.06 mg/kg IM) did not produce significant improvements in pulmonary function compared to placebo
- •Neither beclomethasone nor dexamethasone treatment affected bronchoalveolar lavage fluid cytology or inflammatory cell counts
- •NF-kappaB and AP-1 transcription factor DNA-binding activity showed no suppression with either treatment despite functional improvement with beclomethasone