Equine alveolar macrophages and monocyte-derived macrophages respond differently to an inflammatory stimulus.
Authors: Kang Heng, Lee Gary Kwok Cheong, Bienzle Dorothee, Arroyo Luis G, Sears William, Lillie Brandon N, Beeler-Marfisi Janet
Journal: PloS one
Summary
# Editorial Summary Alveolar macrophages (AMs) and monocyte-derived macrophages (MDMs) are both present during lower airway inflammation in horses, yet their distinct roles in conditions like severe equine asthma remain poorly characterised. Researchers isolated AMs from bronchoalveolar lavage fluid and cultured MDMs from peripheral blood of six healthy horses, then exposed both cell populations to an inflammatory stimulus mimicking asthma exacerbation (inhaled Aspergillus fumigatus, lipopolysaccharide, and silica particles) for six hours whilst measuring surface markers and cytokine production via flow cytometry and multiplex assay. AMs demonstrated significantly higher baseline expression of the scavenger receptors CD163 and CD206 regardless of inflammatory exposure, and mounted a more robust proinflammatory response, producing interleukin-1β, interleukin-8, tumour necrosis factor-α and interferon-γ compared to MDMs, which primarily secreted interleukin-8 and tumour necrosis factor-α alongside the anti-inflammatory interleukin-10. These findings suggest AMs are the primary drivers of acute inflammatory responses in equine lower airway disease, whilst MDMs may play a more regulatory role; however, the in vitro nature of this work means further investigation of how these populations interact within the living lung during both health and disease is essential for translating these findings into targeted therapeutic strategies for managing asthma-prone horses.
Read the full abstract on PubMed
Practical Takeaways
- •Alveolar and blood-derived macrophages behave differently during airway inflammation, which may explain variable severity and progression of lower airway disease between individual horses
- •Understanding these cellular immune differences could inform future therapeutic strategies targeting specific macrophage populations in severe equine asthma cases
- •Further in vivo research is needed to translate these laboratory findings into practical management approaches for horses with inflammatory airway disease
Key Findings
- •Alveolar macrophages (AMs) expressed significantly higher levels of CD163 and CD206 surface markers compared to monocyte-derived macrophages (MDMs) regardless of inflammatory stimulus exposure
- •FLS stimulation induced IL-1β, IL-8, TNF-α and IFN-γ secretion in AMs, but only IL-8, IL-10 and TNF-α in MDMs
- •AMs demonstrated a greater proinflammatory cytokine response to FLS stimulation than MDMs, suggesting distinct functional roles in equine lung inflammation