Comparison of characteristics and enzymatic products of leukocytes in the skin and laminar tissues of horses administered black walnut heartwood extract or lipopolysaccharide.
OBJECTIVE
To compare characteristics and enzymatic products of leukocytes detected in the skin and laminar tissues of horses administered black walnut heartwood extract (BWHE) and horses administered purified lipopolysaccharide (LPS).


METHODS
25 healthy 5- to 15-year-old horses.


METHODS
Horses were randomly assigned to receive LPS (20 ng of O55:B5 Escherichia coli endotoxin/kg; n = 5) IV or 6 L of BWHE (10) or water (control group; 10) via nasogastric intubation. Horses were euthanatized 12 hours after treatment or at onset of Obel grade 1 lameness. Laminar tissue samples and skin samples from the middle region of the neck were harvested at the time of euthanasia. Leukocyte emigration (determined via CD13 immunohistochemical analysis) and matrix metalloproteinase (MMP)-2 and MMP-9 gene expressions and activities (determined via reverse transcription PCR assay and gelatin zymography, respectively) were measured in skin and laminar tissue samples.


RESULTS
Tissues of horses receiving BWHE contained significantly higher numbers of CD13-positive cells and increased MMP-9 gene expression and activity, compared with findings in the other 2 groups. Values for laminar tissue and skin from LPS-treated horses were not increased, compared with findings in the control group, in any experiment.


CONCLUSIONS
Results indicated that BWHE administration causes increases in CD13-positive leukocyte numbers and MMP-9 expression and activity in laminar tissue and skin in horses; similar effects were not detected following LPS administration. Leukocyte emigration in horses with experimentally induced endotoxemia and in horses administered BWHE differed markedly, thereby providing additional evidence that the development of laminitis involves more complex mechanisms than endotoxemia-induced leukocyte activation alone.
Riggs
Laura M
LM
Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA. lriggs@vetmed.lsu.edu
Krunkosky
Thomas M
TM
Noschka
Erik
E
Boozer
Lindsay A
LA
Moore
James N
JN
Robertson
Thomas P
TP
Peroni
John F
JF
D000818:Animals; D005260:Female; D005534:Foot Diseases / Q000139:chemically induced*; D006724:Hoof and Claw / Q000473:pathology; D006734:Horse Diseases / Q000139:chemically induced*; D006736:Horses; D031324:Juglans / Q000737:chemistry; D007962:Leukocytes / Q000187:drug effects / Q000201:enzymology*; D008070:Lipopolysaccharides / Q000633:toxicity*; D008297:Male; D010936:Plant Extracts / Q000633:toxicity*; D012867:Skin / Q000166:cytology*; D014934:Wood / Q000737:chemistry
D008070:Lipopolysaccharides; D010936:Plant Extracts