Asymmetrical Pulmonary Cytokine Profiles Are Linked to Bronchoalveolar Lavage Fluid Cytology of Horses With Mild Airway Neutrophilia.
Authors: Hue Erika, Orard Marie, Toquet Marie-Pierre, Depecker Marianne, Couroucé Anne, Pronost Stéphane, Paillot Romain, Richard Eric A
Journal: Frontiers in veterinary science
Summary
# Editorial Summary Mild equine asthma often presents asymmetrically across the lungs, yet clinical diagnosis typically relies on bronchoalveolar lavage fluid (BALF) sampling from a single lung, potentially missing important pathophysiological information. Researchers compared cytokine profiles between both lungs in 11 Standardbred racehorses showing unilateral mild airway neutrophilia (>10% neutrophils in one lung, <10% in the other), measuring both mRNA expression and protein concentrations of key inflammatory mediators. Interleukin-1β and IL-10 messenger RNA expression were significantly elevated in the affected lung (3.887 and 3.225 fold respectively versus 1.408 and 1.488 in healthy lung), with expression levels correlating meaningfully with neutrophil proportions; however, actual protein concentrations showed no significant differences between lungs. These findings indicate that early inflammatory changes in mild airway disease involve localised gene upregulation within the lower respiratory tract independent of systemic cytokine protein levels, suggesting practitioners should recognise that single-lung sampling may underestimate or miss pathology in horses presenting with subtle clinical signs, and that future diagnostic protocols may benefit from bilateral assessment in cases of suspected mild asthma.
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Practical Takeaways
- •Single-lung bronchoalveolar lavage (BAL) may miss early/localized airway inflammation in racehorses; bilateral sampling or sequential sampling of both lungs should be considered for complete diagnostic assessment
- •Mild airway inflammation detected on BAL reflects genuine localized immune activation (elevated IL-1β and IL-10 mRNA), not laboratory artifact, supporting the clinical relevance of cytological findings even at borderline neutrophil thresholds
- •Horses with unilateral mild neutrophilia on BAL warrant close monitoring and consideration of environmental/training modifications, as local inflammatory regulation is actively occurring
Key Findings
- •IL-1β mRNA expression was 2.76-fold higher in mildly inflamed lungs versus non-inflamed lungs (3.887 ± 0.929 vs 1.408 ± 0.337) and significantly correlated with neutrophil proportions (R = 0.45)
- •IL-10 mRNA expression was 2.17-fold higher in mildly inflamed lungs versus non-inflamed lungs (3.225 ± 0.516 vs 1.488 ± 0.420) and significantly correlated with neutrophil proportions (R = 0.58)
- •Protein concentrations of investigated cytokines showed no significant differences between lungs despite marked mRNA expression differences
- •Asymmetrical cytokine profiles exist between lungs in horses with unilateral mild airway inflammation, suggesting localized inflammatory responses in lower airways