The Effect of Interleukin-4 on Tumour Necrosis Factor-Alpha Induced Expression of Tissue Factor and Plasminogen Activator Inhibitor-1 in Human Umbilical Vein Endothelial Cells

Abstract

The pro-inflammatory cytokine tumour necrosis factor-alpha (TNF-alpha) is able to alter the haemostatic balance of human umbilical vein endothelial cells (HUVECs) towards that of a procoagulant and anti-fibrinolytic state. Treatment of HUVECs in culture with human recombinant TNF-alpha (0.5-50 U/ml; 6 h) significantly increased total cell expression of tissue factor (TF) 10-fold from 40 mU/well to 400-500 mU/well. Levels of plasminogen activator inhibitor-1 (PAI-1) antigen secreted from HUVECs also increased up to 2-fold in concentration-dependent fashion following addition of TNF-alpha (10-100 U/ml; 24 h). TNF-alpha induced total and cell surface expression of TF on HUVECs was significantly inhibited when the cells were pre-incubated with interleukin-4 (IL-4; p < 0.001). This effect was time and concentration dependent. Pretreatment of HUVECs with IL-4 for 4 h had no significant effect, but increasing inhibition of total TF expression occurred after 8 and 16 h pre-incubations. Treatment with IL-4 at 20 and 200 U/ml significantly inhibited cell surface TF responses induced by TNF-alpha, whereas a low concentration (0.2 U/ml) was without effect. In contrast, the production of PAI-1 from HUVECs stimulated by TNF-alpha (50 U/ml) was unaffected by the presence and/or prior incubation with 200 U/ml IL-4. Thus, IL-4 may regulate the pro-coagulant but not the antifibrinolytic effects of TNF-alpha at sites of vascular inflammation.