scholarly journals Precision Targeting of the Plasminogen Activator Inhibitor-1 Mechanism Increases Efficacy of Fibrinolytic Therapy in Empyema

2020 ◽  
Author(s):  
Galina Florova ◽  
René A. Girard ◽  
Ali O. Azghani ◽  
Krishna Sarva ◽  
Ann Buchanan ◽  
...  
Keyword(s):  
Plasminogen Activator ◽  
Therapeutic Dose ◽  
Plasminogen Activator Inhibitor ◽  
Plasminogen Activators ◽  
Fibrinolytic Therapy ◽  
Plasminogen Activator Inhibitor 1 ◽  
Chemically Induced ◽  
Pleural Injury ◽  
Activator Inhibitor ◽  
Pai 1

AbstractPlasminogen activator inhibitor-1 (PAI-1) is an endogenous irreversible inhibitor of tissue-type (tPA) and urokinase (uPA) plasminogen activators. PAI-1-targeted fibrinolytic therapy (PAI-1-TFT) is designed to decrease the therapeutic dose of tPA and uPA to attenuate the risk of bleeding and other complications. The docking site peptide (DSP) is a part of the PAI-1 reactive center loop, which interacts with plasminogen activators, thus affecting the PAI-1 mechanism. We used DSP for PAI-1-TFT in two rabbit models: chemically-induced pleural injury and Streptococcus pneumoniae induced empyema. PAI-1-TFT with DSP combined with single chain uPA or tPA resulted in an up to 8-fold decrease in the minimal effective therapeutic dose of plasminogen activator and induced no bleeding. An increase in the level of PAI-1 in infectious pleural injury, when compared to chemically-induced injury, coincided with an increase in the minimal effective dose of plasminogen activator and DSP. PAI-1 is a valid molecular target in S. pneumoniae empyema model in rabbits, which closely recapitulates key characteristics of empyema in humans. Low dose PAI-1-TFT is a novel precise interventional strategy that may improve fibrinolytic therapy of empyema in clinical practice.

scholarly journals Targeting plasminogen activator inhibitor-1 in tetracycline-induced pleural injury in rabbits

2018 ◽  
Vol 314 (1) ◽  
pp. L54-L68 ◽  
Author(s):  
Galina Florova ◽  
Ali O. Azghani ◽  
Sophia Karandashova ◽  
Chris Schaefer ◽  
Serge V. Yarovoi ◽  
...  
Keyword(s):  
Plasminogen Activator ◽  
Plasminogen Activator Inhibitor ◽  
Fibrinolytic Therapy ◽  
Wild Type ◽  
Plasminogen Activator Inhibitor 1 ◽  
Sandwich Type ◽  
Pleural Injury ◽  
Activator Inhibitor ◽  
Pai 1 ◽  
Selection Of

Elevated active plasminogen activator inhibitor-1 (PAI-1) has an adverse effect on the outcomes of intrapleural fibrinolytic therapy (IPFT) in tetracycline-induced pleural injury in rabbits. To enhance IPFT with prourokinase (scuPA), two mechanistically distinct approaches to targeting PAI-1 were tested: slowing its reaction with urokinase (uPA) and monoclonal antibody (mAb)-mediated PAI-1 inactivation. Removing positively charged residues at the “PAI-1 docking site” (179RHRGGS184→179AAAAAA184) of uPA results in a 60-fold decrease in the rate of inhibition by PAI-1. Mutant prourokinase (0.0625–0.5 mg/kg; n = 12) showed efficacy comparable to wild-type scuPA and did not change IPFT outcomes ( P > 0.05). Notably, the rate of PAI-1-independent intrapleural inactivation of mutant uPA was 2 times higher ( P < 0.05) than that of the wild-type enzyme. Trapping PAI-1 in a “molecular sandwich”-type complex with catalytically inactive two-chain urokinase with Ser195Ala substitution (S195A-tcuPA; 0.1 and 0.5 mg/kg) did not improve the efficacy of IPFT with scuPA (0.0625–0.5 mg/kg; n = 11). IPFT failed in the presence of MA-56A7C10 (0.5 mg/kg; n = 2), which forms a stable intrapleural molecular sandwich complex, allowing active PAI-1 to accumulate by blocking its transition to a latent form. In contrast, inactivation of PAI-1 by accelerating the active-to-latent transition mediated by mAb MA-33B8 (0.5 mg/kg; n = 2) improved the efficacy of IPFT with scuPA (0.25 mg/kg). Thus, under conditions of slow (4–8 h) fibrinolysis in tetracycline-induced pleural injury in rabbits, only the inactivation of PAI-1, but not a decrease in the rate of its reaction with uPA, enhances IPFT. Therefore the rate of fibrinolysis, which varies in different pathologic states, could affect the selection of PAI-1 inhibitors to enhance fibrinolytic therapy.

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.

TNF-α and insulin, alone and synergistically, induce plasminogen activator inhibitor-1 expression in adipocytes

1999 ◽  
Vol 276 (6) ◽  
pp. C1391-C1397 ◽  
Author(s):  
Tomohiro Sakamoto ◽  
Janet Woodcock-Mitchell ◽  
Kousuke Marutsuka ◽  
John J. Mitchell ◽  
Burton E. Sobel ◽  
...  
Keyword(s):  
Plasminogen Activator ◽  
Synergistic Effects ◽  
Plasminogen Activator Inhibitor ◽  
Plasminogen Activators ◽  
System Capacity ◽  
Plasminogen Activator Inhibitor 1 ◽  
Tnf Α ◽  
Factor Α ◽  
Activator Inhibitor ◽  
Pai 1

Obesity is associated with hyperinsulinemia and elevated concentrations of tumor necrosis factor-α (TNF-α) in adipose tissue. TNF-α has been implicated as an inducer of the synthesis of plasminogen activator inhibitor-1 (PAI-1), the primary physiological inhibitor of fibrinolysis, mediated by plasminogen activators in cultured adipocytes. To identify mechanism(s) through which TNF-α induces PAI-1, 3T3-L1 preadipocytes were differentiated into adipocytes and exposed to TNF-α for 24 h. TNF-α selectively increased the synthesis of PAI-1 without increasing activity of plasminogen activators. Both superoxide (generated by xanthine oxidase plus hypoxanthine) and hydrogen peroxide were potent inducers of PAI-1, and hydroxyl radical scavengers completely abolished the TNF-α induction of PAI-1. Exposure of adipocytes to TNF-α or insulin alone over 5 days increased PAI-1 production. These agonists exert synergistic effects. Results obtained suggest that TNF-α stimulates PAI-1 production by adipocytes, an effect potentiated by insulin, and that adipocyte generation of reactive oxygen centered radicals mediates the induction of PAI-1 production by TNF-α. Because induction of PAI-1 by TNF-α is potentiated synergistically by insulin, both agonists appear likely to contribute to the impairment of fibrinolytic system capacity typical in obese, hyperinsulinemic patients.

Induction of the Plasminogen Activator Inhibitor-1 Gene Expression by Mild Hypoxia Via a Hypoxia Response Element Binding the Hypoxia-Inducible Factor-1 in Rat Hepatocytes

Blood ◽  
1999 ◽  
Vol 94 (12) ◽  
pp. 4177-4185 ◽  
Author(s):  
Thomas Kietzmann ◽  
Ulrike Roth ◽  
Kurt Jungermann
Keyword(s):  
Plasminogen Activator ◽  
Hypoxia Inducible Factor ◽  
Plasminogen Activator Inhibitor ◽  
Rat Hepatocytes ◽  
Plasminogen Activators ◽  
Plasminogen Activator Inhibitor 1 ◽  
Hypoxia Response ◽  
Activator Inhibitor ◽  
Pai 1 ◽  
Mild Hypoxia

Plasminogen activator inhibitor-1 (PAI-1) is the primary physiological inhibitor of both tissue-type and urokinase-type plasminogen activators. The balance between plasminogen activators and PAI-1 plays an important role in several physiological and pathophysiological processes such as atherosclerosis or thrombosis. Because these conditions are associated with hypoxia, it was the aim of the present study to investigate the influence of low O2tension on the expression of PAI-1 mRNA and protein using primary cultured rat hepatocytes as a model system. We found that PAI-1 mRNA and protein were induced by mild hypoxia (8% O2). The hypoxia-dependent PAI-1 mRNA induction was transcriptionally regulated because it was inhibited by actinomycin D (ActD). Luciferase (LUC) reporter gene constructs driven by about 800 bp of the 5′-flanking region of the rat PAI-1 gene were transiently transfected into primary rat hepatocytes; mild hypoxia caused a 3-fold induction, which was mediated by the PAI-1 promoter region -175/-158 containing 2 putative hypoxia response elements (HRE) binding the hypoxia-inducible factor (HIF-1). Mutation of the HRE-1 (-175/-168) or HRE-2 (-165/-158) also abolished the induction by mild hypoxia. Cotransfection of a HIF-1 vector and the PAI-1–LUC constructs, as well as gel shift assays, showed that the HRE-2 of the PAI-1 promoter was most critical for induction by hypoxia and HIF-1 binding. Thus, PAI-1 induction by mild hypoxia via a HIF-1 binding HRE in the rat PAI-1 promoter appears to be the mechanism causing the increase in PAI-1 in many clinical conditions associated with O2deficiency.

scholarly journals Fibrin turnover and pleural organization: bench to bedside

2018 ◽  
Vol 314 (5) ◽  
pp. L757-L768 ◽  
Author(s):  
Andrey A. Komissarov ◽  
Najib Rahman ◽  
Y. C. Gary Lee ◽  
Galina Florova ◽  
Sreerama Shetty ◽  
...  
Keyword(s):  
Plasminogen Activator ◽  
Plasminogen Activator Inhibitor ◽  
Fibrinolytic Therapy ◽  
Mesothelial Cells ◽  
Plasminogen Activator Inhibitor 1 ◽  
Mesenchymal Transition ◽  
Pleural Injury ◽  
Activator Inhibitor ◽  
Intrapleural Administration

Recent studies have shed new light on the role of the fibrinolytic system in the pathogenesis of pleural organization, including the mechanisms by which the system regulates mesenchymal transition of mesothelial cells and how that process affects outcomes of pleural injury. The key contribution of plasminogen activator inhibitor-1 to the outcomes of pleural injury is now better understood as is its role in the regulation of intrapleural fibrinolytic therapy. In addition, the mechanisms by which fibrinolysins are processed after intrapleural administration have now been elucidated, informing new candidate diagnostics and therapeutics for pleural loculation and failed drainage. The emergence of new potential interventional targets offers the potential for the development of new and more effective therapeutic candidates.

scholarly journals Failure to Lyse Venous Thrombi Because of Elevated Plasminogen Activator Inhibitor 1 (PAI-1) and 4G Polymorphism of Its Promotor Genome (The PAI-1/4G Syndrome)

2010 ◽  
Vol 16 (5) ◽  
pp. 574-578 ◽  
Author(s):  
Murray M. Bern ◽  
Nancy McCarthy
Keyword(s):  
Plasminogen Activator ◽  
Plasminogen Activator Inhibitor ◽  
Plasminogen Activators ◽  
Plasminogen Activator Inhibitor 1 ◽  
Genomic Changes ◽  
Increased Risk ◽  
High Prevalence ◽  
Residual Thrombus ◽  
Activator Inhibitor ◽  
Pai 1

Plasminogen activator Inhibitor 1 (PAI-1) inhibits plasminogen activators leading to decreased fibrinolysis and increased risk of thromboembolic disease (TED). Shifts in PAI-1 promoter genome from normal 5G>5G to 4G>5G or 4G>4G alleles are associated with overexpression of PAI-1. In this study patients with residual venous thrombi were observed to have increased PAI-1 levels and more frequent shifts to 4G alleles. Of the 26, 20 (76.9%) patients with unresolved thrombus had elevated PAI-1 values. 4G genomic shifts were found in 92.9% patients studied. Normal PAI-1 levels were found in 5 patients with 4G polymorphisms. Thus, PAI-1 is often elevated among patients with residual thrombus, with an unexpectedly high prevalence of the 4G polymorphism of the promoter genome. Patients with persistent thrombus should be considered at risk of having constituently increased PAI-1 due to genomic changes in the PAI-1 promoter genome. Hypotheses are proposed to explain those with normal PAI-1, despite having 4G polymorphisms.

scholarly journals Dose dependency of outcomes of intrapleural fibrinolytic therapy in new rabbit empyema models

2016 ◽  
Vol 311 (2) ◽  
pp. L389-L399 ◽  
Author(s):  
Andrey A. Komissarov ◽  
Galina Florova ◽  
Ali O. Azghani ◽  
Ann Buchanan ◽  
Jake Boren ◽  
...  
Keyword(s):  
Plasminogen Activator ◽  
Pasteurella Multocida ◽  
Plasminogen Activator Inhibitor ◽  
Fibrinolytic Therapy ◽  
Extracellular Dna ◽  
Dose Dependency ◽  
Plasminogen Activator Inhibitor 1 ◽  
Chest Ultrasonography ◽  
Activator Inhibitor ◽  
Pai 1

The incidence of empyema (EMP) is increasing worldwide; EMP generally occurs with pleural loculation and impaired drainage is often treated with intrapleural fibrinolytic therapy (IPFT) or surgery. A number of IPFT options are used clinically with empiric dosing and variable outcomes in adults. To evaluate mechanisms governing intrapleural fibrinolysis and disease outcomes, models of Pasteurella multocida and Streptococcus pneumoniae were generated in rabbits and the animals were treated with either human tissue (tPA) plasminogen activator or prourokinase (scuPA). Rabbit EMP was characterized by the development of pleural adhesions detectable by chest ultrasonography and fibrinous coating of the pleura. Similar to human EMP, rabbits with EMP accumulated sizable, 20- to 40-ml fibrinopurulent pleural effusions associated with extensive intrapleural organization, significantly increased pleural thickness, suppression of fibrinolytic and plasminogen-activating activities, and accumulation of high levels of plasminogen activator inhibitor 1, plasminogen, and extracellular DNA. IPFT with tPA (0.145 mg/kg) or scuPA (0.5 mg/kg) was ineffective in rabbit EMP ( n = 9 and 3 for P. multocida and S. pneumoniae, respectively); 2 mg/kg tPA or scuPA IPFT ( n = 5) effectively cleared S. pneumoniae-induced EMP collections in 24 h with no bleeding observed. Although intrapleural fibrinolytic activity for up to 40 min after IPFT was similar for effective and ineffective doses of fibrinolysin, it was lower for tPA than for scuPA treatments. These results demonstrate similarities between rabbit and human EMP, the importance of pleural fluid PAI-1 activity, and levels of plasminogen in the regulation of intrapleural fibrinolysis and illustrate the dose dependency of IPFT outcomes in EMP.

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

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.

Induction of the Plasminogen Activator Inhibitor-1 Gene Expression by Mild Hypoxia Via a Hypoxia Response Element Binding the Hypoxia-Inducible Factor-1 in Rat Hepatocytes

Blood ◽  
1999 ◽  
Vol 94 (12) ◽  
pp. 4177-4185 ◽  
Author(s):  
Thomas Kietzmann ◽  
Ulrike Roth ◽  
Kurt Jungermann
Keyword(s):  
Plasminogen Activator ◽  
Hypoxia Inducible Factor ◽  
Plasminogen Activator Inhibitor ◽  
Rat Hepatocytes ◽  
Plasminogen Activators ◽  
Plasminogen Activator Inhibitor 1 ◽  
Hypoxia Response ◽  
Activator Inhibitor ◽  
Pai 1 ◽  
Mild Hypoxia

Abstract Plasminogen activator inhibitor-1 (PAI-1) is the primary physiological inhibitor of both tissue-type and urokinase-type plasminogen activators. The balance between plasminogen activators and PAI-1 plays an important role in several physiological and pathophysiological processes such as atherosclerosis or thrombosis. Because these conditions are associated with hypoxia, it was the aim of the present study to investigate the influence of low O2tension on the expression of PAI-1 mRNA and protein using primary cultured rat hepatocytes as a model system. We found that PAI-1 mRNA and protein were induced by mild hypoxia (8% O2). The hypoxia-dependent PAI-1 mRNA induction was transcriptionally regulated because it was inhibited by actinomycin D (ActD). Luciferase (LUC) reporter gene constructs driven by about 800 bp of the 5′-flanking region of the rat PAI-1 gene were transiently transfected into primary rat hepatocytes; mild hypoxia caused a 3-fold induction, which was mediated by the PAI-1 promoter region -175/-158 containing 2 putative hypoxia response elements (HRE) binding the hypoxia-inducible factor (HIF-1). Mutation of the HRE-1 (-175/-168) or HRE-2 (-165/-158) also abolished the induction by mild hypoxia. Cotransfection of a HIF-1 vector and the PAI-1–LUC constructs, as well as gel shift assays, showed that the HRE-2 of the PAI-1 promoter was most critical for induction by hypoxia and HIF-1 binding. Thus, PAI-1 induction by mild hypoxia via a HIF-1 binding HRE in the rat PAI-1 promoter appears to be the mechanism causing the increase in PAI-1 in many clinical conditions associated with O2deficiency.

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