Flow cytometric analysis of equine bronchoalveolar lavage fluid cells in horses with and without severe equine asthma.
Authors: Kang Heng, Bienzle Dorothee, Lee Gary Kwok Cheong, Piché Érica, Viel Laurent, Odemuyiwa Solomon Olawole, Beeler-Marfisi Janet
Journal: Veterinary pathology
Summary
# Editorial Summary: Flow Cytometric Profiling of Airway Cells in Severe Equine Asthma Severe equine asthma represents a significant welfare and performance concern in older horses, driven by lower airway inflammation triggered when alveolar macrophages encounter dusty barn conditions and shift towards a pro-inflammatory state, subsequently recruiting neutrophils to the lungs. Researchers developed and validated a multi-colour flow cytometry panel using monoclonal antibodies (CD90, CD163, CD206) to characterise leukocyte populations in bronchoalveolar lavage fluid, then compared airway cell responses in four healthy horses and four SEA-susceptible horses before and after a 48-hour moldy hay challenge. CD163 and CD206 surface expression on alveolar macrophages increased significantly post-challenge only in SEA-susceptible animals (P = .02 and P = .03 respectively), whereas control horses showed minimal phenotypic changes, suggesting that macrophage activation markers correlate with susceptibility to asthmatic exacerbation. These findings establish reliable immunophenotyping tools for investigating equine airway inflammation and indicate that macrophage polarisation may be central to SEA pathogenesis, though the precise functional mechanisms driving disease progression remain to be clarified. For practitioners managing asthmatic horses, this work underscores the importance of controlling environmental triggers (hay quality, stable ventilation) that provoke potentially irreversible macrophage activation in susceptible individuals.
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Practical Takeaways
- •This research identifies specific markers (CD163 and CD206) that distinguish inflammatory alveolar macrophages in horses with SEA, which could potentially support diagnosis or monitoring of the condition
- •The phenotypic switch in macrophages appears to be a key mechanism in SEA development; understanding this may eventually lead to targeted anti-inflammatory therapies beyond current management
- •Moldy hay exposure reliably triggers the measurable inflammatory response in susceptible horses, confirming the importance of environmental management in SEA cases
Key Findings
- •CD90 antibodies uniquely labeled equine neutrophils, while CD163 and CD206 identified equine macrophages in bronchoalveolar lavage fluid
- •Post-challenge alveolar macrophage surface expression of CD163 increased significantly in SEA-susceptible horses (P = .02) but not controls
- •CD206 expression on alveolar macrophages increased significantly in SEA-susceptible horses (P = .03) but remained unchanged in controls (P = .5)
- •Increased CD163 and CD206 expression during SEA exacerbation suggests an association between alveolar macrophage phenotype and lung inflammation