scholarly journals Mechanism of protein C-dependent clot lysis: role of plasminogen activator inhibitor

Blood ◽  
1986 ◽  
Vol 68 (6) ◽  
pp. 1218-1223 ◽  
Author(s):  
Y Sakata ◽  
DJ Loskutoff ◽  
CL Gladson ◽  
CM Hekman ◽  
JH Griffin
Keyword(s):  
Plasminogen Activator ◽  
Protein C ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Activated Protein C ◽  
Plasminogen Activator Inhibitor ◽  
Species Specificity ◽  
Tissue Type ◽  
Clot Lysis ◽  
Activator Inhibitor

Abstract The mechanism by which activated protein C stimulates fibrinolysis was studied in a simple radiolabeled clot lysis assay system containing purified tissue-type plasminogen activator, bovine endothelial plasminogen activator inhibitor (PAI), plasminogen, 125I-fibrinogen and thrombin. Fibrinolysis was greatly enhanced by the addition of purified bovine activated protein C; however, in the absence of PAI, activated protein C did not stimulate clot lysis, thus implicating this inhibitor in the mechanism. In clot lysis assay systems containing washed human platelets as a source of PAI, bovine-activated protein C-dependent fibrinolysis was associated with a marked decrease in PAI activity as detected using reverse fibrin autography. Bovine-activated protein C also decreased PAI activity of whole blood and of serum. In contrast to the bovine molecule, human-activated protein C was much less profibrinolytic in these clot lysis assay systems and much less potent in causing the neutralization of PAI. This species specificity of activated protein C in clot lysis assays reflect the known in vivo profibrinolytic species specificity. When purified bovine-activated protein C was mixed with purified PAI, complex formation was demonstrated using immunoblotting techniques after polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. These observations suggest that a major mechanism for bovine protein C- dependent fibrinolysis in in vitro clot lysis assays involves a direct neutralization of PAI by activated protein C.

scholarly journals Mechanism of protein C-dependent clot lysis: role of plasminogen activator inhibitor

Blood ◽  
1986 ◽  
Vol 68 (6) ◽  
pp. 1218-1223
Author(s):  
Y Sakata ◽  
DJ Loskutoff ◽  
CL Gladson ◽  
CM Hekman ◽  
JH Griffin
Keyword(s):  
Plasminogen Activator ◽  
Protein C ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Activated Protein C ◽  
Plasminogen Activator Inhibitor ◽  
Species Specificity ◽  
Tissue Type ◽  
Clot Lysis ◽  
Activator Inhibitor

The mechanism by which activated protein C stimulates fibrinolysis was studied in a simple radiolabeled clot lysis assay system containing purified tissue-type plasminogen activator, bovine endothelial plasminogen activator inhibitor (PAI), plasminogen, 125I-fibrinogen and thrombin. Fibrinolysis was greatly enhanced by the addition of purified bovine activated protein C; however, in the absence of PAI, activated protein C did not stimulate clot lysis, thus implicating this inhibitor in the mechanism. In clot lysis assay systems containing washed human platelets as a source of PAI, bovine-activated protein C-dependent fibrinolysis was associated with a marked decrease in PAI activity as detected using reverse fibrin autography. Bovine-activated protein C also decreased PAI activity of whole blood and of serum. In contrast to the bovine molecule, human-activated protein C was much less profibrinolytic in these clot lysis assay systems and much less potent in causing the neutralization of PAI. This species specificity of activated protein C in clot lysis assays reflect the known in vivo profibrinolytic species specificity. When purified bovine-activated protein C was mixed with purified PAI, complex formation was demonstrated using immunoblotting techniques after polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. These observations suggest that a major mechanism for bovine protein C- dependent fibrinolysis in in vitro clot lysis assays involves a direct neutralization of PAI by activated protein C.

Activated Protein C Increases Fibrin Clot Lysis by Neutralization of Plasminogen Activator Inhibitor No Evidence for a Cofactor Role of Protein S

1988 ◽  
Vol 60 (02) ◽  
pp. 328-333 ◽  
Author(s):  
N J de Fouw ◽  
Y F de Jong ◽  
F Haverkate ◽  
R M Bertina
Keyword(s):  
Plasminogen Activator ◽  
Protein C ◽  
Blood Platelets ◽  
Plasminogen Activator Inhibitor ◽  
Protein S ◽  
Tissue Type ◽  
Clot Lysis ◽  
Activator Inhibitor ◽  
Pai 1

summaryThe effect of purified human activated protein G (APC) on fibrinolysis was studied using a clot iysis system consisting of purified glu-plasminogen, tissue-type plasminogen activator, plasminogen activator inhibitor (released from endothelial cells or blood platelets), fibrinogen, 125T-fibrinogen and thrombin. All proteins were of human origin.In this system APC could increase fibrinolysis in a dose dependent way, without affecting fibrin formation or fibrin crosslinking. However, this profibrinolytic effect of APC could only be observed when plasminogen activator inhibitor (PAI-l) was present. The effect of APC was completely quenched by pretreatment of APC with anti-protein C IgG or di-isopropylfluorophosphate. Addition of the cofactors of APC:protein S, Ca2+-ions and phospholipid-alone or in combination did not enhance the profibrinolytic effect of APC. These observations indicate that human APC can accelerate in vitro clot lysis by the inactivation of PAI-1 activity. However, the neutralization of PAI-1 by APC is independent of the presence or absence of protein S, phospholipid and Ca2+-ions.

scholarly journals Plasma tissue plasminogen activator and plasminogen activator inhibitor-1 in hospitalized COVID-19 patients

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yu Zuo ◽  
Mark Warnock ◽  
Alyssa Harbaugh ◽  
Srilakshmi Yalavarthi ◽  
Kelsey Gockman ◽  
...  
Keyword(s):  
Plasminogen Activator ◽  
Ex Vivo ◽  
Plasminogen Activator Inhibitor ◽  
Tissue Type ◽  
Bleeding Complications ◽  
Clot Lysis ◽  
Thrombosis Prophylaxis ◽  
Plasminogen Activator Inhibitor 1 ◽  
Activator Inhibitor ◽  
Pai 1

AbstractPatients with coronavirus disease-19 (COVID-19) are at high risk for thrombotic arterial and venous occlusions. However, bleeding complications have also been observed in some patients. Understanding the balance between coagulation and fibrinolysis will help inform optimal approaches to thrombosis prophylaxis and potential utility of fibrinolytic-targeted therapies. 118 hospitalized COVID-19 patients and 30 healthy controls were included in the study. We measured plasma antigen levels of tissue-type plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1) and performed spontaneous clot-lysis assays. We found markedly elevated tPA and PAI-1 levels in patients hospitalized with COVID-19. Both factors demonstrated strong correlations with neutrophil counts and markers of neutrophil activation. High levels of tPA and PAI-1 were associated with worse respiratory status. High levels of tPA, in particular, were strongly correlated with mortality and a significant enhancement in spontaneous ex vivo clot-lysis. While both tPA and PAI-1 are elevated among COVID-19 patients, extremely high levels of tPA enhance spontaneous fibrinolysis and are significantly associated with mortality in some patients. These data indicate that fibrinolytic homeostasis in COVID-19 is complex with a subset of patients expressing a balance of factors that may favor fibrinolysis. Further study of tPA as a biomarker is warranted.

scholarly journals The interaction of plasminogen activator inhibitor 1 with plasminogen activators (tissue-type and urokinase-type) and fibrin: localization of interaction sites and physiologic relevance

Blood ◽  
1991 ◽  
Vol 78 (2) ◽  
pp. 401-409 ◽  
Author(s):  
J Keijer ◽  
M Linders ◽  
AJ van Zonneveld ◽  
HJ Ehrlich ◽  
JP de Boer ◽  
...  
Keyword(s):  
Plasminogen Activator ◽  
Regulatory Protein ◽  
Plasminogen Activator Inhibitor ◽  
Plasminogen Activators ◽  
Tissue Type ◽  
Clot Lysis ◽  
Plasminogen Activator Inhibitor 1 ◽  
Interaction Sites ◽  
Activator Inhibitor ◽  
Pai 1

Abstract Plasminogen activator inhibitor 1 (PAI-1), an essential regulatory protein of the fibrinolytic system, harbors interaction sites for plasminogen activators (tissue-type [t-PA] and urokinase-type [u-PA]) and for fibrin. In this study, anti-PAI-1 monoclonal antibodies (MoAbs) were used to identify interaction sites of PAI-1 with these components. The binding sites of 18 different MoAbs were established and are located on five distinct “linear” areas of PAI-1. MoAbs, binding to two distinct areas of PAI-1, are able to prevent the inhibition of t-PA by PAI-1. In addition, two interaction sites for fibrin were identified on PAI-1. The area located between amino acids 110 and 145 of PAI-1 contains a binding site for both components and its significance is discussed in the context of the t-PA inhibition by fibrin-bound PAI-1. Subsequently, the MoAbs were used to assess the role of platelet-PAI-1 in clot-lysis. An in vitro clot-lysis system was used to demonstrate that clot-lysis resistance is dependent on the presence of activated platelets and that PAI-1 is a major determinant for lysis-resistance. We propose that, upon activation of platelets, PAI-1 is fixed within the clot by binding to fibrin and retains its full capacity to inhibit t-PA and u-PA.

Biological Rational for the Use of Heparin in Septic Shock: Translational Data from the Halo Pilot RCT

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 2336-2336
Author(s):  
Brett L. Houston ◽  
Dhruva J. Dwivedi ◽  
Peter Grin ◽  
Michelle Kwong ◽  
Enrico Rullo ◽  
...  
Keyword(s):  
Septic Shock ◽  
Protein C ◽  
Thrombin Generation ◽  
Activated Protein C ◽  
Plasminogen Activator Inhibitor ◽  
Clot Lysis ◽  
Plasminogen Activator Inhibitor 1 ◽  
Lysis Time ◽  
Activator Inhibitor ◽  
Clot Lysis Time

Abstract BACKGROUND: Sepsis is a leading cause of mortality among critically ill patients and is associated with both systemic inflammation and up-regulation of coagulation. In the translational sub-study of the HALO (Heparin AnticoaguLation to improve Outcomes in septic shock) pilot trial, we evaluated the mechanisms by which unfractionated heparin (UFH) may reduce inflammation and coagulation in patients with septic shock. METHODS: In this multicenter pilot randomized trial of 69 patients diagnosed with septic shock, we evaluated the feasibility of administering therapeutic dose intravenous UFH (18 IU/kg/hr) compared to thromboprophylactic subcutaneous dalteparin (5000 IU daily). Blood samples were collected on days 1 (baseline prior to study infusion), 2, 3, 5, and 7. We evaluated coagulation using assays for protein C, activated protein C, thrombin-antithrombin (TAT), thrombin generation, clot lysis, plasminogen activator inhibitor-1 (PAI-1) and cell-free DNA (cf-DNA). Systematic inflammation was evaluated by measuring inflammatory cytokines (interleukin (IL)-6, IL-8, IL-10, and IL-17). RESULTS: The mean age of the study population was 61 years, of whom 43% were male. Thirty two patients (46%) were randomized to receive unfractionated heparin while 37 (54%) received dalteparin. The baseline mean aggregate Acute Physiology and Chronic Health Evaluation II (APACHE II) score was 25 ± 7.8, and Multiple Organ Dysfunction Score (MODS) 5.6 ± 2.38. Baseline laboratory testing (coagulation assays and inflammatory cytokines) was not statistically different between UFH vs. LMWH treated patients. On day 2, the median clot lysis time in UFH-treated patients compared to those receiving dalteparin was significantly decreased [6630 (IQR 0 - 14156) seconds vs. 9615 (IQR 8209 - 11018) seconds; p = 0.008] (Figure 1). UFH administration was associated with increased protein C levels [66.4% of normal (IQR 9.9 - 122.9) vs. 41.1% of normal (IQR 4.8 - 77.4); p = 0.02], and reduced thrombin generation of 0 (IQR 0 - 1725) units/min vs. 3393 (IQR 0 - 8519) units/min; p<0.001]. On day 2, we observed no differences between thrombin-antithrombin complex (TAT), activated protein C, plasminogen activator inhibitor-1 (PAI-1) or cell-free DNA (cf-DNA). Similarly, there were no differences between treatment groups in inflammatory markers, including IL-6, IL-8, IL-10 or IL-17. Analysis thus far is limited to samples collected on days 1 and 2; day 3-7 analyses are ongoing. CONCLUSION: In patients diagnosed with septic shock, IV UFH reduces thrombin generation, shortens clot lysis time and improves endogenous protein C levels compared to dalteparin administered for thromboprophylaxis. Analyses for samples obtained on days 3, 5 and 7 are ongoing. These preliminary data provide a biologic rational for the use of heparin in sepsis. Figure 1. Differences in clot lysis, protein C and thrombin generation in patients treated with UFH vs. LMWH. UFH is associated with reduced thrombin generation, improved Protein C levels, and reduced clot lysis time. Figure 1. Differences in clot lysis, protein C and thrombin generation in patients treated with UFH vs. LMWH. UFH is associated with reduced thrombin generation, improved Protein C levels, and reduced clot lysis time. Disclosures No relevant conflicts of interest to declare.

scholarly journals A comparison between activated protein C and des-1-41-light chain- activated protein C in reactions with type 1 plasminogen activator inhibitor

Blood ◽  
1989 ◽  
Vol 74 (1) ◽  
pp. 173-181
Author(s):  
CL Gladson ◽  
RR Schleef ◽  
BR Binder ◽  
DJ Loskutoff ◽  
JH Griffin
Keyword(s):  
Plasminogen Activator ◽  
Light Chain ◽  
Protein C ◽  
Activated Protein C ◽  
Plasminogen Activator Inhibitor ◽  
Amidolytic Activity ◽  
Gla Domain ◽  
Activator Inhibitor ◽  
Pai 1

This study investigates the role of the gamma-carboxyglutamic acid (gla) containing domain of activated protein C in interactions with both platelet-derived and purified type 1 plasminogen activator inhibitor (PAI-1). The activity of human platelet PAI-1 was neutralized to the same extent by bovine activated protein C and bovine des-1–41- light chain-activated protein C. Both forms of activated protein C formed SDS-stable, divalent-cation independent complexes with platelet PAI-1, as demonstrated by immunoblotting using antibodies directed to either protein C or PAI-1. Since activated protein C neutralized PAI-1, the potential inhibition of the enzyme by PAI-1 was studied. Purified PAI-1 inhibited the amidolytic activity of bovine-activated protein C and bovine des-1–41-light chain-activated protein C with a k2 of 2.85 X 10(4) M-1 sec-1 for both proteins. These data suggest that the gla domain of activated protein C is not required for neutralization of PAI- 1 activity, for complex formation with PAI-1, or for inhibition of the amidolytic activity of activated protein C by PAI-1.

The Role of the Finger Domain of Tissue-type Plasminogen Activator (t-PA) and Plasminogen Activator Inhibitor 1 (PAI-1) in Initiation and Progression of Thrombolysis

1994 ◽  
Vol 72 (06) ◽  
pp. 900-905 ◽  
Author(s):  
Harold A R Stringer ◽  
Peter van Swieten ◽  
Anton J G Horrevoets ◽  
Annelies Smilde ◽  
Hans Pannekoek
Keyword(s):  
Plasminogen Activator ◽  
Plasminogen Activator Inhibitor ◽  
Tissue Type ◽  
Clot Lysis ◽  
Plasminogen Activator Inhibitor 1 ◽  
Tissue Type Plasminogen Activator ◽  
Type Plasminogen Activator ◽  
Activator Inhibitor ◽  
Pai 1

SummaryWe further investigated the role of the finger (F) and the kringle-2 (K2) domains of tissue-type plasminogen activator (t-PA) in fibrin-stimulated plasminogen activation. To that end, the action of purified (wt) t-PA or of variants lacking F (del.F) or K2 (del.K2) was assessed either in a static, human whole blood clot-lysis system or in whole blood thrombi generated in the “Chandler loop”. In both clot-lysis systems, significant differences were observed for the initiation of thrombolysis with equimolar concentrations of the t-PA variants. A relatively minor “lag phase” occurred in thrombolysis mediated by wt t-PA, whereas a 6.4-fold and 1.6-fold extension is found for del.F and del.K2, respectively. We observed identical lag-times, characteristic for each t-PA variant, in platelet-rich heads and in platelet-poor tails of thrombi. Since plasminogen activator inhibitor 1 (PAI-1) is preferentially retained in the platelet-rich heads, we conclude that the inhibitor does not interfere with the initial stage of thrombolysis but exerts its action in later stages, resulting in a reduction of the rate of clot lysis. A complementation clot-lysis assay was devised to study a potential interplay of del.F and del.K2. Accordingly, clot lysis was determined with combinations of del.F and del.K2 that were inversely varied in relation to equipotent dosage to distinguish between additive, antagonistic or synergistic effects of these variants. The isobole for combinations of del.F and del.K2 shows an independent, additive action of del.F and del.K2 in clot lysis. Under the conditions employed, namely a relatively high concentration of fibrin and Glu-plasminogen and a low concentration of t-PA variant, our data show: i) the crucial role of the F domain and the lack of effect of PAI-1 in initiation of thrombolysis, ii) the lack of importance of the fibrimbinding domains of t-PA and the regulatory role of PAI-1 in advanced stages of thrombolysis.

Sign in / Sign up

Export Citation Format

Share Document