Thromboxane and isoprostanes as inflammatory and vasoactive mediators in black walnut heartwood extract induced equine laminitis.
Authors: Noschka, Moore, Peroni, Lewis, Morrow, Robertson
Journal: Veterinary immunology and immunopathology
Summary
# Editorial Summary Black walnut heartwood extract (BWHE) triggers concurrent inflammation and vascular dysfunction in equine laminitis, yet the precise molecular mechanisms linking these processes remain poorly understood. To investigate, researchers administered BWHE or saline to horses and measured circulating and tissue concentrations of thromboxane and isoprostanes—potent vasoactive lipid mediators—whilst simultaneously assessing vascular responsiveness using small vessel myography. Plasma thromboxane surged transiently following BWHE administration and coincided with white blood cell depletion, whilst laminar tissue isoprostane (specifically iso-PGF₂ₐ) concentrations rose significantly; critically, laminar veins from laminitic horses exhibited exaggerated contractile responses to isoprostane PGF₂ₐ compared to controls, despite showing reduced sensitivity to thromboxane mimetics. Importantly, when thromboxane receptors were pharmacologically blocked, isoprostane-induced venoconstriction persisted in laminitic tissue but reversed in healthy tissue, suggesting fundamental alterations in vascular receptor expression or signalling during laminitis development. These findings implicate laminar venous tissue as a critical interface between systemic inflammation and local vascular collapse, positioning isoprostanes and thromboxane as potential therapeutic targets; practitioners should consider that future interventions targeting prostanoid pathways—particularly isoprostane production or receptor function—may help preserve laminar microvascular perfusion during the prodromal phase when such damage remains reversible.
Read the full abstract on PubMed
Practical Takeaways
- •Thromboxane and isoprostane-mediated vascular constriction in laminar tissue may be a treatable component of laminitis; future therapies targeting these pathways warrant investigation
- •The heightened responsiveness of laminar veins to isoprostanes in laminitic horses suggests selective vascular dysfunction that differs from systemic responses, indicating need for targeted rather than systemic interventions
- •Understanding the inflammatory cascade involving these eicosanoids may help identify earlier therapeutic windows during the prodromal stage of laminitis when intervention could be most effective
Key Findings
- •Plasma thromboxane concentrations increased transiently after BWHE administration and coincided with nadir white blood cell counts
- •Laminar tissue iso-PGF(2alpha) concentrations were significantly greater in BWHE-induced laminitis horses compared to controls
- •Laminar veins from BWHE horses showed significantly greater constrictor responses to iso-PGF(2alpha) compared to control horses
- •Thromboxane and isoprostanes may serve as conduits between inflammatory and vascular events in laminitis pathogenesis and represent potential therapeutic targets