title: Ex-vivo regulation of endotoxin-induced tissue factor in whole blood by eicosanoids.
abstract: The influence of several eicosanoids of the lipoxygenase pathway was examined in an ex vivo system of human whole blood subjected to stimulation by lipopolysaccharide (LPS). Exogenously added leukotriene B4 [5(S),12(R)-dihydroxy-6,14-cis-8,10-trans-eicosatetraenoic acid (LTB4)] or 12(S)-hydroxyeicosatetraenoic acid (12(S)-HETE) significantly (P<0.05) enhanced LPS-evoked expression of monocyte tissue factor (TF) activity in a concentration-dependent manner. 15(S)-HETE, on the other hand, exerted such activity only when added at certain concentrations, whereas 5(S)-HETE was devoid of any apparent activity. LPS-induced TF activity was inhibited by the lipoxygenase inhibitors nordihydroguaiaretic acid, CGS 23885 and ZM 230487, by 59, 32 and 88%, respectively. Furthermore, the production of LTB4 in LPS-stimulated whole blood was investigated, in the absence or presence of either tumor necrosis factor alpha (TNFalpha) or phorbol-12-myristate-13-acetate (PMA). LPS alone induced a moderate time-dependent and concentration-dependent release of LTB4, reaching the maximum concentration (1260 +/- 202 pg/ml) within 90 min at 5 ng/ml LPS. The prior and concurrent presence of PMA (5 ng/ml) or TNFalpha (10 ng/ml) further enhanced the LTB4 production approximately twofold (P < 0.05). TNFalpha added alone evoked approximately twice the LTB4 production seen when LPS (2200 +/- 243 versus 1260 +/- 203 pg/ml) was added alone. Considering these results, LPS and TNFalpha emerge as important agonists of LTB4 production in whole blood. LTB4 in turn appears to be of importance for the expression of TF in monocytes, potentially amplifying the thrombogenic potential of these cells.
authors.affiliation: Department of Biochemistry, Institute of Medical Biology, Faculty of Medicine, University of Tromsø, Norway. Karl-Erik.Eilertsen@fagmed.uit.no
authors.forename: Karl-Erik
authors.initials: KE
authors.lastname: Eilertsen
authors.forename: Jan Ole
authors.initials: JO
authors.lastname: Olsen
authors.forename: Bjarne
authors.initials: B
authors.lastname: Østerud
mesh_terms: D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid / Q000494:pharmacology; D001769:Blood / Q000187:drug effects / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D015777:Eicosanoids / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007975:Leukotriene B4 / Q000096:biosynthesis / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013925:Thromboplastin / Q000096:biosynthesis* / Q000187:drug effects*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D015777:Eicosanoids; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D007975:Leukotriene B4; D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; D013925:Thromboplastin; D013755:Tetradecanoylphorbol Acetate