Recombinant human C1-inhibitor prevents non-specific proteolysis by mutant pro-urokinase during optimal fibrinolysis.
A single-site mutant of prouPA (M5) spared haemostatic fibrin during thrombolysis in dogs. Zymograms of plasma from these dogs showed an unusual inhibitor complex with C1-inhibitor (C1I). Purified C1I added to human plasma enhanced the fibrin-specificity of M5. In the present study, the effect of recombinant human C1I (recC1I) on high-dose M5 and tPA were compared using fluorescein-labeled standardised clots in a plasma milieu. The shortest time to complete clot lysis (maximum rate) was first determined. This was approximately 65% per hour for both activators. By contrast, their top fibrin-specific lysis rate (<20% fibrinogen depletion) was less than half maximum (25-30% per hour). Adding recC1I (250-750 microg/ml) did not affect fibrinolysis, but prevented fibrinogenolysis and plasminogen depletion by M5, raising its fibrin-specific lysis rate to the maximum. With tPA, the recC1I modestly attenuated fibrinogenolysis, raising its fibrin-specific rate to about half the maximum. Consistent with this, the t(1/2) inhibition by C1I was approximately 90 min for tPA compared with ~10 min for tcM5. The t(1/2) of C1I for plasmin was ~2 min. Zymograms of plasma after clot lysis indicated that recC1I prevented non-specific tcM5 generation from M5, as evidenced by suppression of tcM5:C1I complexes. In conclusion, recC1I raised the fibrin-specificity of M5 in plasma so that a maximum lysis rate could be achieved without fibrinogenolysis. The inhibition by C1I of non-specific but not fibrin-dependent plasminogen activation could not be duplicated by other serpins. The findings provide a potential means to optimize both the efficacy and safety of thrombolysis.
Gurewich
Victor
V
Beth Israel Deaconess Medical Center, Harvard Medical School, Cambridge, MA 02138, USA. vgurewic@bidmc.harvard.edu
Pannell
Ralph
R
D000818:Animals; D003174:Complement C1 Inactivator Proteins / Q000494:pharmacology*; D004285:Dogs; D005340:Fibrinogen / Q000378:metabolism; D005341:Fibrinolysin / Q000037:antagonists & inhibitors; D005342:Fibrinolysis / Q000187:drug effects* / Q000502:physiology; D005343:Fibrinolytic Agents / Q000008:administration & dosage / Q000009:adverse effects; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D016297:Mutagenesis, Site-Directed; D010958:Plasminogen / Q000378:metabolism; D017395:Plasminogen Activator Inhibitor 1 / Q000494:pharmacology; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000009:adverse effects / Q000037:antagonists & inhibitors / Q000235:genetics / Q000494:pharmacology; D015912:Thrombolytic Therapy / Q000009:adverse effects / Q000379:methods; D010959:Tissue Plasminogen Activator / Q000008:administration & dosage / Q000009:adverse effects / Q000037:antagonists & inhibitors; D014568:Urokinase-Type Plasminogen Activator / Q000008:administration & dosage* / Q000009:adverse effects / Q000037:antagonists & inhibitors / Q000235:genetics*; D000979:alpha-2-Antiplasmin / Q000494:pharmacology
D003174:Complement C1 Inactivator Proteins; D005343:Fibrinolytic Agents; D017395:Plasminogen Activator Inhibitor 1; D011994:Recombinant Proteins; D000979:alpha-2-Antiplasmin; D005340:Fibrinogen; D010958:Plasminogen; D010959:Tissue Plasminogen Activator; D005341:Fibrinolysin; D014568:Urokinase-Type Plasminogen Activator; C067551:saruplase