Role of catalytic and lysine-binding sites in plasmin-induced neutrophil adherence to endothelium.

Abstract

Plasmin resulted in increased neutrophil adherence to cultured ovine pulmonary artery endothelial cell monolayers in a concentration-dependent manner (102-40'7 M). The adherence response increased fivefold above baseline within 60 min after addition of plasmin (10-8 M) and the response persisted up to 30 min after removal of plasmin. The neutrophil adherence was mediated by the action of plasmin on neutrophils rather than endothelial cells. The response was the result of an increase in functional activity of CD18 neutrophil cell surface adhesive glycoprotein. Neutrophil adherence was inhibited by pretreatment of neutrophils with MAbs IB4 and 60.3 targeted against the ,B chain of the CD18, whereas control isotypic MAb 60.5 against HLA class I antigen had no effect. The plasmin catalytic site was not involved in the response. Lys-plasminogen had reduced adherence-promoting activity relative to plasmin, whereas glu-plasminogen had no effect. Elastase-derived plasminogen fragments corresponding to kringle 1+2+3 and kringle 4 (both of which contained the lysine-binding sites) possessed neutrophil adherence-promoting activities similar to plasmin, whereas miniplasminogen (which contains the catalytic site but no lysine-binding sites) had minimal effect, indicating the involvement of lysine-binding sites in the response. Blocking lysine-bihding sites of plasmin and elastase-derived plasminogen fragments with tranexamic acid (IC50 of 5 mM) inhibited neutrophil adherence. A monospecific polyclonal antibody against the lysine-binding sites also reduced the neutrophil adherence-promoting activity of plasmin. The results indicate that plasmin induces neutrophil adherence to the endothelium and that the effect is mediated by lysine-binding sites on plasmin.

Plasmin generation induces neutrophil aggregation: Dependence on the catalytic and lysine binding sites

“…The generation of plasmin on the surface of PMNs may lead to their activation. We have previously demonstrated that plasmin but not plasminogen causes PMN adherence to cultured endothelial cell monolayers, an effect mediated by the lysine binding sites on plasmin (Lo et al, 1989). In the present study, we examined the effects of either preformed plasmin or plasmin generated by plasminogen activators on the aggregation of PMN and the molecular basis for the response.…”

“…The relationship between polymorphonuclear leukocytes (PMN) and the fibrinolytic system may be important in the pathogenesis of tissue injury during inflammation (Lo et al, 1989;Malik, 1990). For example, fibrin degradation products generated by plasmin during fibrinolysis after PMN function (Kazura et al, 1989).…”

Inhibition of Plasmin Activity by Tranexamic Acid Does Not Influence Inflammatory Pathways During Human Endotoxemia

“…33 Plasmin induced neutrophil aggregation and increased neutrophil adhesion to endothelial cells in vitro, an effect that could be inhibited by tranexamic acid. 19,20,27 The plasmin-induced neutrophil adherence was mediated through an upregulation of CD18 neutrophil cell surface glycoprotein, reflecting neutrophil activation. These data suggest that plasmin is able to activate neutrophils, which can be abrogated by tranexamic acid.…”

“…26 In vitro, tranexamic acid potently inhibited plasmin-induced proinflammatory responses. 13,19,27 The fact that the formation of plasmin is one of the earliest-occurring events after intravenous administration of LPS, together with the recent findings that plasmin is able to induce several cellular proinflammatory responses, including activation of p38 MAPK, led us to hypothesize that plasmin may play a role in the induction of LPS-induced inflammatory pathways. To test this hypothesis, we studied the effect of tranexamic acid infusion on activation of coagulation, granulocytes, endothelial cells, and the cytokine network in healthy humans injected with a single dose of LPS.…”

Novel aspects and new roles for the serine protease plasmin

“…It is possible that the adhesion molecule CD18 is involved in the aggregation. CD18 is activated in neutrophils after stimulation with plasmin [100]. Expression of two types of adhesion molecules on endothelial cells and neutrophils may provide the basis of the CD18-P-selectin-mediated adhesion of neutrophils to endothelial cells.…”