The Endotoxin-induced Plasminogen Activator Inhibitor-1 Increase in Rabbits Is Not Tumor Necrosis Factor-α Dependent and Can Occur in the Absence of Interleukin-1β

SummaryThe plasminogen activator inhibitor-1 (PAI-1)-dependent fibrinolytic inhibition occurring in endotoxemia contributes to disseminated intravascular coagulation (DIC). Previous findings suggest that tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) are responsible for the increase in the level of PAI-1. These observations usually arose from mild endotoxemia models. We analyzed the effect of FR167653, an inhibitor of the TNF-α/IL-1β production, on the PAI-1 levels in rabbits given endotoxin at a dose sufficient to induce DIC: the steep plasma PAI-1 increase was not attenuated by FR167653, in spite of achieving efficient inhibition of the TNF-α production. No IL-1β was detected during endotoxemia. These results suggest that PAI-1 increase might be independent of TNF-α and IL-1β. If these findings applied to humans, therapeutic intervention directing these cytokines would not be useful for the treatment of fibrinolysis in patients with severe sepsis.