CT-1501R SELECTIVELY INHIBITS INDUCED INFLAMMATORY MONOKINES IN HUMANWHOLE-BLOOD EX-VIVO

The effect of (R)-1-(5-hydroxyhexyl)-3,7-dimethylxanthine (CT-1501R; t he nonproprietary name for CT-1501R approved by the United States Name Council is lisofylline), an inhibitor of second messenger signaling t hrough phosphatidic acid, on release of endogenous mediators important in the systemic inflammatory response syndrome (SIRS) was studied usi ng the human whole blood ex vivo assay system. Human blood was stimula ted with various endotoxin preparations, zymosan, or protein A, and th e levels of secreted monokines were measured by enzyme-linked immunoso rbent assay. CT-1501R inhibited tumor necrosis factor alpha (TNF-alpha ), interleukin 1beta (IL-1beta), and IL-6 release in a dose-dependent manner and was active with all stimuli tested including Salmonella and Escherichia coli-derived endotoxin, endotoxin from both rough and smo oth E. coli strains, as well as zymosan and protein A. CT-1501R inhibi ted monokine release by approximately 50% at 200 muM and 30% at 50 muM and was independent of the relative potency of stimulus. CT-1501R als o inhibited IL-1alpha or IL-1beta induction of either TNF-alpha or IL- 1beta and inhibited the synergistic effects of stimulation with both h uman IL-1beta and murine TNF-alpha on release of human TNF-alpha. Inhi bition of monokine release following stimulation with monokine(s) was, in general, greater than that achieved with lipopolysaccharide (LPS) stimulation. Northern blot analysis showed decreased mRNA accumulation of TNF-alpha and IL-1beta in CT-1501R-treated samples following LPS s timulation suggesting that CT-1501R acts at least in part, at the pret ranslational level. In contrast, CT-1501R does not inhibit LPS-stimula ted IL-8 or IL-1 receptor antagonist (IL-1ra) release in human whole b lood or IL-1alpha-induced release of PGE2 in human foreskin fibroblast cells. These data suggest that CT-1501R may be of use for clinical in tervention in SIRS.