Interleukin 1 induces endothelial cell procoagulant while suppressing cell-surface anticoagulant activity.

Abstract

Previous studies demonstrated that endothelial cells participate actively in both anticoagulant and procoagulant reactions. Although anticoagulant mechanisms predominate on the surface of quiescent endothelial cells, perturbed endothelial cells can promote coagulation through the coordinated induction of procoagulant activity and suppression of anticoagulant mechanisms. Purified recombinant interleukin 1 was infused intravenously into rabbits and coagulant 'properties of the native aortic endothelium were subsequently studied. Interleukin 1 infusion resulted in a timeand dose-dependent induction of the procoagulant cofactor tissue factor, while concomitantly blocking~the protein C anticoagulant pathway. Tissue factor activity increased >10-fold by 3-5 hr after the infusion,. while endothelial celldependent thrombin-mediated protein; C activation decreased by 72% and assembly of functional activated protein C-protein S complex, on the vessel surface was decreased by >90%. This has led us to examine in vivo the effect of IL-1 infusion in the rabbit on procoagulant and anticoagulant properties of the native aortic endothelium. MATERIALS AND METHODSReagents and Assays. Infusion studies were carried out using recombinant murine IL-1 (15), generously provided by Peter LoMedico (Hoffmann La Roche). Heat treatment of IL-1 was carried out at 90'C for 70 min (19) and resulted in loss of IL-1 activity in the thymocyte costimulator assay (20). Control protein, a single-chain polypeptide ofMr 17,000, was also purified from Escherichia coli (provided by Peter LoMedico). This protein, distinct from IL-1, has no IL-1 or other known biologic activity and was also free of detectable endotoxin.Human factor X (130 units/ml) was purified to homogeneity by the method of DiScipio et al. (21), and purified human factor VIIa (22) was generously provided by W. Kisiel (University of New Mexico, Albuquerque, NM). These reagents Were used to assay the tissue factor by incubating samples with factors VIIa (8 nM) and X (1.1 aM) for 10 min at 21'C in incubation buffer [10 mM Hepes (pH 7.45) containing 137 mM NaCl, 4 mM KCl, 11 mM glucose, 2.5 mM CaCl2, and fatty acid-free bovine serum albumin (2 mg/ml)] at a final vol of 0.1 ml. One sample was removed from each reaction mixture, added to 0.5 ml of 50 mM Tris HCl, pH 7.8/175 mM NaCl/10 mM EDTA/ovalbumin (0.5 mg/ml), and assayed for factor Xa by monitoring hydrolysis at 405 nM of the chromogenic substrate S2222 (Bz-Ile-Glu-Gly-Arg-pnitroanilide; Helena Laboratories, Beaumont; TX) (0.1 ml; 0.5 nM) (23). Factors VIta and X were present at saturating concentrations and factor Xa formation, which was linear, was limited only by the amount of tissue factor. a-Thrombin (2.5 units/,ug), antithrombin III (inhibitory activity of 1.0 unit of thrombin per pug), and protein C were purified to homogeneity from bovine plasma, as described (24-26). Thrombin-mediated protein C activation was studied as described (18) Human protein S and bovine factor Va were purified to homogeneity as described (21, 28)...

Tissue Factor Binding of Activated Factor VII Triggers Smooth Muscle Cell Proliferation via Extracellular Signal–Regulated Kinase Activation

“…15 In recent years, however, it became evident that TF has additional biological functions apart from activating coagulation. One of the first indications for a nonhemostatic function of TF was its characterization as an immediate early gene that can be induced during cell division 16 and in response to pathophysiologically relevant stimuli, such as cytokines, 17 growth factors, 18 oxidized LDL, 19 and oxygen free radicals. 20 An exciting recent development in TF biology was the demonstration that this protein, a member of the cytokine receptor superfamily, can function as a true signaling receptor.…”

Plasma Levels of Soluble Thrombomodulin, C-reactive Protein, and Serum Amyloid A Protein in the Atherosclerotic Coronary Circulation

“…An in vitro study showed that oxidized LDL reduced TM expression on endothelial cell surfaces, 15) and TM mRNA expression was reduced by the pro-inflammatory cytokines IL-1 16) and TNF. 17) Therefore, TM expression may be reduced by these atherogenic pro-inflammatory cytokines on the endothelial cells of atherosclerotic coronary arteries.…”

Endothelial cell functions

“…However, when exposed to thrombin, cytokines, or LPS, endothelial cells synthesize and express tissue factor at their surface (Nawroth et al, 1986;Mackman, 1997). Once coagulation has been initiated, endothelial cells promote thrombi activation since the activity of factor Xa (generated by tissue factor plus factor VII) is locally enhanced by promotion of binding with its cofactor Va at adjacent Xa and Va receptors on the endothelial cell surface (Davie et al, 1991;Chen et al, 2001).…”