Effects of the second-generation synthetic lipid A analogue E5564 on responses to endotoxin in [corrected] equine whole blood and monocytes.
OBJECTIVE
To evaluate proinflammatory effects of the second-generation synthetic lipid A analogue E5564 on equine whole blood and isolated monocytes and to determine the ability of E5564 to prevent LPS (lipopolysaccharide)-induced procoagulant activity (PCA); tumor necrosis factor (TNF)-alpha production; and mRNA expression of TNF-alpha, interleukin (IL)-1beta, IL-6, and IL-10 by equine monocytes.


METHODS
Venous blood samples obtained from 19 healthy horses.


METHODS
Whole blood and monocytes were incubated with Escherichia coli O111:B4 LPS, E5564, or E5564 plus E coli O111:B4 LPS. Whole blood and cell supernatants were assayed for TNF-alpha, and cell lysates were assayed to determine PCA. Expression of mRNA for TNF-alpha, IL-1beta, IL-6, and IL-10 by monocytes was determined by use of real-time quantitative PCR assay.


RESULTS
Minimal proinflammatory effects were detected in whole blood and monocytes. In addition, E5564 inhibited LPS-induced PCA and TNF-alpha production in a concentration-dependent manner. Furthermore, E5564 significantly inhibited LPS-induced mRNA expression of TNF-alpha, IL-1beta, and IL-10 and decreased LPS-induced expression of IL-6.


CONCLUSIONS
The second-generation synthetic lipid A analogue E5564 lacked agonist activity in equine whole blood and monocytes and was a potent antagonist of enteric LPS. Therefore, E5564 appeared to be the first lipid A analogue that has potential as an effective therapeutic agent in horses with endotoxemia.
Department of Physiology and Pharmacology and Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602-7385, USA.
Monica D
MD
Figueiredo
James N
JN
Moore
Michel L
ML
Vandenplas
Wan-chun
WC
Sun
Thomas F
TF
Murray
D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D006736:Horses / Q000097:blood* / Q000276:immunology; D020128:Inhibitory Concentration 50; D016753:Interleukin-10 / Q000096:biosynthesis / Q000235:genetics; D053583:Interleukin-1beta / Q000096:biosynthesis / Q000235:genetics; D015850:Interleukin-6 / Q000096:biosynthesis / Q000235:genetics; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000276:immunology; D008050:Lipid A / Q000031:analogs & derivatives* / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D016133:Polymerase Chain Reaction / Q000662:veterinary; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000235:genetics
D000893:Anti-Inflammatory Agents; C404742:E5564; D053583:Interleukin-1beta; D015850:Interleukin-6; D008050:Lipid A; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10