Outer membrane vesicles from Neisseria meningitidis: Effects on tissue factor and plasminogen activator inhibitor-2 production in human monocytes

Lipopolysaccharide-containing outer membrane vesicles (OMV-LPS) which are s pontaneously released from Neisseria meningitidis during logarithmic growth were studied for their ability to induce procoagulant (tissue factor), pro fibrinolytic (urokinase-type plasminogen activator) and antifibrinolytic (p lasminogen activator inhibitor-2) factors in purified human monocytes. Cell -associated tissue factor was 5.0-fold (n=5) increased, peaking after 8 h, in the presence of OMV-LPS (1 mug/ml, final concentration). Plasminogen act ivator inhibitor-2 release from monocytes was maximal after 24 h OMV-LPS (1 mug/ml) stimulation and 13.7-fold (n=5) increased compared to controls; wh ereas urokinase-type plasmonigen activator antigen in culture medium remain ed uninfluenced by OMV-LPS. In conclusion, these OMV-induced imbalances fav or fibrin deposition in the monocyte microenvironment and is probably of gr eat importance in the development of disseminated intravascular coagulation , microthrombosis and organ dysfunction related to fulminant meningococcal septicemia. (C) 2001 Elsevier Science Ltd. All rights reserved.