Cytotoxicity of stimulated equine neutrophils on equine endothelial cells in culture.
Authors: Benbarek H, Grülke S, Deby-Dupont G, Deby C, Mathy-Hartert M, Caudron I, Dessy-Doize C, Lamy M, Serteyn D
Journal: Equine veterinary journal
Summary
# Editorial Summary Neutrophil activation during acute inflammation can damage endothelial tissue through soluble mediators alone, without requiring direct cell-to-cell contact—a finding with significant implications for understanding systemic inflammatory responses in horses. Researchers cultured equine carotid endothelial cells and exposed them either to activated neutrophils or to cell-free supernatant from stimulated neutrophils, measuring cytotoxicity through chromium-51 release and microscopy. Activated neutrophils caused marked endothelial damage with approximately 50% cell loss and structural alterations in remaining cells; critically, the supernatant from these neutrophils reproduced this toxicity in direct proportion to neutrophil numbers and myeloperoxidase concentration. Using isolated reactive oxygen species systems (hypoxanthine/xanthine oxidase) and hypochlorite, the authors demonstrated that myeloperoxidase activity—particularly its hypochlorite products—was the primary driver of endothelial injury rather than superoxide or hydrogen peroxide alone. These findings suggest that in conditions characterised by systemic neutrophil activation (such as sepsis, endotoxaemia, or severe colic), vascular and tissue damage can propagate far from the primary inflammatory site through circulating neutrophil-derived mediators, potentially explaining the widespread organ involvement seen clinically in these conditions and pointing toward the importance of controlling neutrophil activation as a therapeutic strategy.
Read the full abstract on PubMed
Practical Takeaways
- •Understanding that neutrophil activation during inflammatory conditions can cause widespread endothelial damage beyond the primary site of inflammation may help explain multi-tissue complications in acute equine inflammatory diseases
- •Myeloperoxidase appears to be a critical mediator of neutrophil-induced tissue damage, suggesting it may be a therapeutic target in conditions with excessive neutrophil activation such as sepsis or SIRS
- •The ability of neutrophil supernatants alone to damage endothelium reinforces that managing systemic inflammation requires controlling neutrophil activation, not just addressing local inflammation
Key Findings
- •Supernatant from stimulated equine neutrophils caused significant endotoxicity with 50% loss of endothelial cells, independent of direct cell contact
- •Myeloperoxidase activity was the primary driver of endothelial damage, with cytotoxicity correlating to myeloperoxidase concentration in the supernatant
- •Hypochlorite (myeloperoxidase product) showed high toxicity to endothelial cells, while reactive oxygen species alone produced only weak cytotoxicity
- •In acute inflammatory states with neutrophil activation, endothelial damage can occur in tissues distant from the inflammation focus through circulating neutrophil-derived mediators