Equine neutrophil elastase in plasma, laminar tissue, and skin of horses administered black walnut heartwood extract (BWHE)

Abstract Title: Equine neutrophil elastase in plasma, laminar tissue, and skin of horses administered black walnut heartwood extract (BWHE)

Author(s) Name(s) & Institutional Affiliation(s):
Geoffroy de la Rebière de Pouyade1, 2, Laura. M. Riggs3, J. N. Moore4, Thierry Franck1, 2, Ginette Deby-Dupont2, David J. Hurley4,5, and Didier Serteyn1, 2

1-Department of Clinical Sciences, Large Animal Surgery, Faculty of Veterinary Medicine B41, University of Liège, Sart Tilman, 4000 Liège, Belgium
2-Center for Oxygen Research and Development, Institute of Chemistry B6a, University of Liège, Sart Tilman, 4000 Liège, Belgium
3-Department of Equine Surgery, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803
4-Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602
5-Department of Population Health, College of Veterinary Medicine, University of Georgia, Athens, GA 30602

Take Home Message: Elastase concentrations are increased in the integument of horses during the developmental phase of BWHE-induced laminitis.

Introduction:
Current evidence suggests the involvement of neutrophils and myeloperoxidase (MPO), a strong oxidative enzyme in the development of laminitis. Elastase is a protease recognized as a component of inflammatory disorders. Neutrophil elastase concentrations were measured in plasma, skin and laminar tissues from control horses and horses given BWHE

Materials & Methods (including Statistical Analyses): The study included 4 groups, a control group (water) and 3 experimental groups (BWHE). Plasma was obtained hourly until euthanasia of BWHE-treated horses at 1.5 (n=5), 3 (n=6), and 12 hours (n=10 plasma/n=6 tissue) and control horses at 12 hours (n=7 plasma/n=5 tissue). Elastase concentrations were determined via ELISA. Log-transformed data were analyzed with 1-way ANOVA (tissues) and unpaired t-test (plasma); significance was set at P<0.05.

Results: Plasma elastase concentrations in the BWHE group were significantly higher at 6, 8 and 10h compared to the control group. Concentrations in skin and laminar tissue were significantly higher at 3 and 12h in the BWHE group. Elastase concentrations were significantly higher in skin than in lamina at 12h in BWHE group.

Discussion: Increased elastase concentrations are consistent with dynamic changes in circulating leukocytes in horses given BWHE. Collectively, MPO and elastase have the potential to cause significant tissue damage during the development of laminitis.

Clinical Relevance: Elastase may become an important target as new treatments for laminitis are developed.

Conclusion: Elastase concentrations increase in the integumentary system during the development of laminitis and may participate in the disintegration of the hoof basal membrane.