The vitronectin-binding function of PAI-1 exacerbates lung fibrosis in mice

Abstract Plasminogen activator inhibitor-1 (PAI-1) is increased in the lungs of patients with pulmonary fibrosis, and animal studies have shown that experimental manipulations of PAI-1 levels directly influence the extent of scarring that follows lung injury. PAI-1 has 2 known properties that could potentiate fibrosis, namely an antiprotease activity that inhibits the generation of plasmin, and a vitronectin-binding function that interferes with cell adhesion to this extracellular matrix protein. To determine the relative importance of each PAI-1 function in lung fibrogenesis, we administered mutant PAI-1 proteins that possessed either intact antiprotease or vitronectin-binding activity to bleomycin-injured mice genetically deficient in PAI-1. We found that the vitronectin-binding capacity of PAI-1 was the primary determinant required for its ability to exacerbate lung scarring induced by intratracheal bleomycin administration. The critical role of the vitronectin-binding function of PAI-1 in fibrosis was confirmed in the bleomycin model using mice genetically modified to express the mutant PAI-1 proteins. We conclude that the vitronectin-binding function of PAI-1 is necessary and sufficient in its ability to exacerbate fibrotic processes in the lung.

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Thymosin β4 induces the synthesis of plasminogen activator inhibitor 1 in cultured endothelial cells and increases its extracellular expression

Blood ◽

10.1182/blood-2003-04-1015 ◽

2004 ◽

Vol 103 (4) ◽

pp. 1319-1324 ◽

Cited By ~ 32

Author(s):

Khalid N. I. Al-Nedawi ◽

Malgorzata Czyz ◽

Radoslaw Bednarek ◽

Janusz Szemraj ◽

Maria Swiatkowska ◽

...

Keyword(s):

Endothelial Cells ◽

Plasminogen Activator ◽

Human Fibroblasts ◽

Plasminogen Activator Inhibitor ◽

Binding Activity ◽

Mitogen Activated Protein Kinase ◽

Thymosin Β4 ◽

Plasminogen Activator Inhibitor 1 ◽

Activator Inhibitor ◽

Pai 1

Abstract Thymosin β4(Tβ4), a 4.9-kDa polypeptide primarily known as a main G-actin–sequestering peptide, is present in high concentrations in various cells and in the circulation. We have found that Tβ4 upregulates the expression of plasminogen activator inhibitor 1 (PAI-1) in endothelial cells measured both at the level of mRNA and protein synthesis. This effect seems to be cell specific and was not observed when other cells such as human fibroblasts, PC3, and U937 were tested. Tβ4 significantly activated the PAI-1 promoter in EA.hy 926 cells transiently transfected either with plasmid p800LUC containing PAI-1 promoter fragment (–800 to +71) or the PAI-1 promoter linked with green fluorescent protein. Tβ4 mediated up-regulation of PAI-1 involved activation of the mitogen-activated protein kinase cascade. Furthermore, Tβ4 enhanced c-Fos/c-Jun DNA-binding activity to the activator protein 1 (AP-1)–like element (–59 to –52). The specificity of this binding activity was demonstrated by competition electrophoretic mobility shift assay and after transfection of EA.hy 926 cells with the mutated PAI-1 promoter. Taken together, these data indicate that, in response to Tβ4 stimulation, AP-1 activity increases to enhance PAI-1 transcription through its unique AP-1–like element at –59 to –52 in the PAI-1 promoter.

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Functional Stability of Plasminogen Activator Inhibitor-1

The Scientific World JOURNAL ◽

10.1155/2014/858293 ◽

2014 ◽

Vol 2014 ◽

pp. 1-11 ◽

Cited By ~ 39

Author(s):

Songul Yasar Yildiz ◽

Pinar Kuru ◽

Ebru Toksoy Oner ◽

Mehmet Agirbasli

Keyword(s):

Plasminogen Activator ◽

Biological Effects ◽

Critical Role ◽

Plasma Concentrations ◽

Plasminogen Activator Inhibitor ◽

Tissue Type ◽

Plasminogen Activator Inhibitor 1 ◽

Type Plasminogen Activator ◽

Activator Inhibitor ◽

Pai 1

Plasminogen activator inhibitor-1 (PAI-1) is the main inhibitor of plasminogen activators, such as tissue-type plasminogen activator (t-PA) and urokinase-type plasminogen activator (u-PA), and a major regulator of the fibrinolytic system. PAI-1 plays a pivotal role in acute thrombotic events such as deep vein thrombosis (DVT) and myocardial infarction (MI). The biological effects of PAI-1 extend far beyond thrombosis including its critical role in fibrotic disorders, atherosclerosis, renal and pulmonary fibrosis, type-2 diabetes, and cancer. The conversion of PAI-1 from the active to the latent conformation appears to be unique among serpins in that it occurs spontaneously at a relatively rapid rate. Latency transition is believed to represent a regulatory mechanism, reducing the risk of thrombosis from a prolonged antifibrinolytic action of PAI-1. Thus, relying solely on plasma concentrations of PAI-1 without assessing its function may be misleading in interpreting the role of PAI-1 in many complex diseases. Environmental conditions, interaction with other proteins, mutations, and glycosylation are the main factors that have a significant impact on the stability of the PAI-1 structure. This review provides an overview on the current knowledge on PAI-1 especially importance of PAI-1 level and stability and highlights the potential use of PAI-1 inhibitors for treating cardiovascular disease.

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943: Plasminogen Activator Inhibitor 1 (PAI-1) is Increased in Human Peyronie's Disease

The Journal of Urology ◽

10.1016/s0022-5347(18)35099-7 ◽

2005 ◽

Vol 173 (4S) ◽

pp. 255-255 ◽

Cited By ~ 1

Author(s):

Hugo H. Davila ◽

Thomas R. Magee ◽

Freddy Zuniga ◽

Jacob Rajfer ◽

Nestor F. GonzalezCadavid

Keyword(s):

Plasminogen Activator ◽

Plasminogen Activator Inhibitor ◽

Peyronie’S Disease ◽

Plasminogen Activator Inhibitor 1 ◽

Peyronie's Disease ◽

Activator Inhibitor ◽

Pai 1

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Relationship of Plasminogen Activator Inhibitor-1 Levels following Thrombolytic Therapy with rt-PA as Compared to Streptokinase and Patency of Infarct Related Coronary Artery

Thrombosis and Haemostasis ◽

10.1055/s-0037-1614637 ◽

1999 ◽

Vol 82 (07) ◽

pp. 104-108 ◽

Cited By ~ 13

Author(s):

Franck Paganelli ◽

Marie Christine Alessi ◽

Pierre Morange ◽

Jean Michel Maixent ◽

Samuel Lévy ◽

...

Keyword(s):

Myocardial Infarction ◽

Acute Myocardial Infarction ◽

Thrombolytic Therapy ◽

Plasminogen Activator ◽

Plasminogen Activator Inhibitor ◽

Control Group ◽

Plasminogen Activator Inhibitor 1 ◽

Vessel Patency ◽

Activator Inhibitor ◽

Pai 1

Summary Background: Type 1 plasminogen activator inhibitor (PAI-1) is considered to be risk factor for acute myocardial infarction (AMI). A rebound of circulating PAI-1 has been reported after rt-PA administration. We investigated the relationships between PAI-1 levels before and after thrombolytic therapy with streptokinase (SK) as compared to rt-PA and the patency of infarct-related arteries. Methods and Results: Fifty five consecutive patients with acute MI were randomized to strep-tokinase or rt-PA. The plasma PAI-1 levels were studied before and serially within 24 h after thrombolytic administration. Vessel patency was assessed by an angiogram at 5 ± 1days. The PAI-1 levels increased significantly with both rt-PA and SK as shown by the levels obtained from a control group of 10 patients treated with coronary angioplasty alone. However, the area under the PAI-1 curve was significantly higher with SK than with rt-PA (p <0.01) and the plasma PAI-1 levels peaked later with SK than with rt-PA (18 h versus 3 h respectively). Conversely to PAI-1 levels on admission, the PAI-1 levels after thrombolysis were related to vessel patency. Plasma PAI-1 levels 6 and 18 h after SK therapy and the area under the PAI-1 curve were significantly higher in patients with occluded arteries (p <0.002, p <0.04 and p <0.05 respectively).The same tendency was observed in the t-PA group without reaching significance. Conclusions: This study showed that the PAI-1 level increase is more pronounced after SK treatment than after t-PA treatment. There is a relationship between increased PAI-1 levels after thrombolytic therapy and poor patency. Therapeutic approaches aimed at quenching PAI-1 activity after thrombolysis might be of interest to improve the efficacy of thrombolytic therapy for acute myocardial infarction.

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Fibrinolysis in Normal Subjects - Comparison Between Plasminogen Activator Inhibitor and Other Components of the Fibrinolytic System

Thrombosis and Haemostasis ◽

10.1055/s-0038-1642775 ◽

1988 ◽

Vol 59 (02) ◽

pp. 299-303 ◽

Cited By ~ 40

Author(s):

Grazia Nicoloso ◽

Jacques Hauert ◽

Egbert K O Kruithof ◽

Guy Van Melle ◽

Fedor Bachmann

Keyword(s):

Plasminogen Activator ◽

Fibrinolytic Activity ◽

Plasminogen Activator Inhibitor ◽

Venous Occlusion ◽

Venous Stasis ◽

Plasminogen Activator Inhibitor 1 ◽

Plate Assay ◽

Fibrin Plate ◽

Activator Inhibitor ◽

Pai 1

SummaryWe analyzed fibrinolytic parameters in 20 healthy men and 20 healthy women, aged from 25 to 59, before and after 10 and 20 min venous occlusion. The 10 min post-occlusion fibrinolytic activity measured directly in diluted unfractionated plasma by a highly sensitive 125I-fibrin plate assay correlated well with the activity of euglobulins determined by the classical fibrin plate assay (r = 0.729), but pre-stasis activities determined with these two methods did not correlate (r = 0.084). The enhancement of fibrinolytic activity after venous occlusion was mainly due to an increase of t-PA in the occluded vessels (4-fold increase t-PA antigen after 10 min and 8-fold after 20 min venous occlusion). Plasminogen activator inhibitor (PAI) activity and plasminogen activator inhibitor 1 (PAI-1)1 antigen levels at rest showed considerable dispersion ranging from 1.9 to 12.4 U/ml, respectively 6.9 to 77 ng/ml. A significant increase of PAI-1 antigen levels was observed after 10 and 20 min venous occlusion. At rest no correlation was found between PAI activity or PAI-1 antigen levels and the fibrinolytic activity measured by 125I-FPA. However, a high level of PAI-1 at rest was associated with a high prestasis antigen level of t-PA and a low fibrinolytic response after 10 min of venous stasis. Since the fibrinolytic response inversely correlated with PAI activity at rest, we conclude that its degree depends mainly on the presence of free PAI.

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Polymorphisms of the Plasminogen Activator Inhibitor- 1 Gene in Type 1 and Type 2 Diabetes, and in Patients with Diabetic Retinopathy

Thrombosis and Haemostasis ◽

10.1055/s-0038-1642514 ◽

1994 ◽

Vol 71 (06) ◽

pp. 731-736 ◽

Cited By ~ 29

Author(s):

M W Mansfield ◽

M H Stickland ◽

A M Carter ◽

P J Grant

Keyword(s):

Diabetic Retinopathy ◽

Plasminogen Activator Inhibitor ◽

Allelic Frequency ◽

Repeat Sequence ◽

Dinucleotide Repeat ◽

Plasminogen Activator Inhibitor 1 ◽

The Difference ◽

Pai 1

SummaryTo identify whether genotype contributes to the difference in PAI-1 levels in type 1 and type 2 diabetic subjects and whether genotype relates to the development of retinopathy, a Hind III restriction fragment length polymorphism and two dinucleotide repeat polymorphisms were studied. In 519 Caucasian diabetic subjects (192 type 1, 327 type 2) and 123 Caucasian control subjects there were no differences in the frequency of the Hind III restriction alleles (type 1 vs type 2 vs control: allele 1 0.397 vs 0.420 vs 0.448; allele 2 0.603 vs 0.580 vs 0.552) nor in the allelic frequency at either dinucleotide repeat sequence. In 86 subjects with no retinopathy at 15 years or more from diagnosis of diabetes and 190 subjects with diabetic retinopathy there was no difference in the frequency of Hind III restriction alleles (retinopathy present vs retinopathy absent: allele 1 0.400 vs 0.467; allele 2 0.600 vs 0.533) nor in the allelic frequencies at either dinucleotide repeat sequence. The results indicate that there is no or minimal influence of the PAI-1 gene on either PAI-1 levels or the development of diabetic retinopathy in patients with diabetes mellitus.

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Limited Proteolysis of Vitronectin by Plasmin Destroys Heparin Binding Activity

Thrombosis and Haemostasis ◽

10.1055/s-0038-1646413 ◽

1991 ◽

Vol 66 (03) ◽

pp. 310-314 ◽

Cited By ~ 12

Author(s):

David C Sane ◽

Tammy L Moser ◽

Charles S Greenberg

Keyword(s):

Limited Proteolysis ◽

Plasminogen Activator Inhibitor ◽

Binding Activity ◽

Binding Domain ◽

Heparin Binding ◽

Inhibitor Type ◽

Activator Inhibitor Type ◽

Activator Inhibitor ◽

Pai 1

SummaryVitronectin (VN) stabilizes plasminogen activator inhibitor type 1 (PAI-1) activity and prevents the fibrin(ogen)-induced acceleration of plasminogen activation by t-PA. These antifibrinolytic activities as well as other functions are mediated by the glycosaminoglycan (GAG) binding domain of VN. Since the GAG binding region is rich in arginyl and lysyl residues, it is a potential target for enzymes such as plasmin. In this paper, the dose and time-dependent proteolysis of VN by plasmin is demonstrated. The addition of urokinase or streptokinase (200 units/ml) to plasma also produced proteolysis of VN. With minimal proteolysis, the 75 kDa band was degraded to a 62-65 kDa form of VN. This minimal proteolysis destroyed the binding of [3H]-heparin to VN and reversed the neutralization of heparin by VN.Thus, the plasmin-mediated proteolysis of the GAG binding activity of VN could destroy the antifibrinolytic activity of VN during physiologic conditions and during thrombolytic therapy. Furthermore, other functions of VN in complement and coagulation systems that are mediated by the GAG binding domain may be destroyed by plasmin proteolysis.

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A Specific Immunologic Assay for Functional Plasminogen Activator Inhibitor 1 in Plasma – Standardized Measurements of the Inhibitor and Related Parameters in Patients with Venous Thromboembolic Disease

Thrombosis and Haemostasis ◽

10.1055/s-0038-1646305 ◽

1992 ◽

Vol 68 (05) ◽

pp. 486-494 ◽

Cited By ~ 15

Author(s):

Malou Philips ◽

Anne-Grethe Juul ◽

Johan Selmer ◽

Bent Lind ◽

Sixtus Thorsen

Keyword(s):

Plasminogen Activator ◽

Plasminogen Activator Inhibitor ◽

Normal Subjects ◽

Tissue Type ◽

Blood Collection ◽

Plasminogen Activator Inhibitor 1 ◽

Type Plasminogen Activator ◽

Significant Difference ◽

Activator Inhibitor ◽

Pai 1

SummaryA new assay for functional plasminogen activator inhibitor 1 (PAI-1) in plasma was developed. The assay is based on the quantitative conversion of PAI-1 to urokinase-type plasminogen activator (u-PA)-PAI-l complex the concentration of which is then determined by an ELISA employing monoclonal anti-PAI-1 as catching antibody and monoclonal anti-u-PA as detecting antibody. The assay exhibits high sensitivity, specificity, accuracy, and precision. The level of functional PAI-1, tissue-type plasminogen activator (t-PA) activity and t-PA-PAI-1 complex was measured in normal subjects and in patients with venous thromboembolism in a silent phase. Blood collection procedures and calibration of the respective assays were rigorously standardized. It was found that the patients had a decreased fibrinolytic capacity. This could be ascribed to high plasma levels of PAI-1. The release of t-PA during venous occlusion of an arm for 10 min expressed as the increase in t-PA + t-PA-PAI-1 complex exhibited great variation and no significant difference could be demonstrated between the patients with a thrombotic tendency and the normal subjects.

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Relation between Plasminogen Activator Inhibitor-1 and Hepatic Enzyme Concentrations in Hyperlipidemic Patients

Thrombosis and Haemostasis ◽

10.1055/s-0038-1648885 ◽

1994 ◽

Vol 72 (03) ◽

pp. 434-437 ◽

Cited By ~ 10

Author(s):

E Bruckert ◽

A Ankri ◽

P Glral ◽

G Turpin

Keyword(s):

Blood Pressure ◽

Plasminogen Activator ◽

Plasminogen Activator Inhibitor ◽

Tolerance Test ◽

High Plasma ◽

Oral Glucose ◽

Plasminogen Activator Inhibitor 1 ◽

Glutamyl Transferase ◽

Activator Inhibitor ◽

Pai 1

SummaryPlasminogen activator inhibitor type-1 (PAI-1) is a key determinant of the fibrinolytic capacity. Its activity correlates with most of the characteristic features of insulin resistance syndrome, i. e. obesity, high blood pressure and hyperlipidemia.We measured plasma PAI-1 antigen levels in 131 asymptomatic men (aged 44.2 ± 11 years) who had been referred for hyperlipidemia. Those taking medication and those with a secondary hyperlipidemia were excluded.We confirmed the correlation between PAI-1 levels and the following variables: body mass index, blood pressure, triglyceride concentration, and blood glucose and insulin levels before and after an oral glucose tolerance test. We also found a significant and independent correlation between PAI-1 and the concentration of the hepatic enzymes glutamyl transferase, alanine aminotransferase and aspartate aminotransferase.Mild liver abnormalities (presumably steatosis) may thus be one of the factors accounting for high plasma PAI-1 levels in hyperlipidemic patients.

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Anti-thrombotic Effect of a PAI-1 Inhibitor in Rats Given Endotoxin

Thrombosis and Haemostasis ◽

10.1055/s-0038-1650231 ◽

1996 ◽

Vol 75 (01) ◽

pp. 118-126 ◽

Cited By ~ 27

Author(s):

T Abrahamsson ◽

V Nerme ◽

M Strömqvist ◽

B Åkerblom ◽

A Legnehed ◽

...

Keyword(s):

Plasminogen Activator Inhibitor ◽

Rat Plasma ◽

Clot Lysis ◽

Fibrin Deposition ◽

Plasminogen Activator Inhibitor 1 ◽

Fab Fragment ◽

Dose Dependent Decrease ◽

Pai 1

SummaryThe aim of this study was to investigate the anti-thrombotic effects of an inhibitor of the plasminogen activator inhibitor-1 (PAI-1) in rats given endotoxin. In studies in vitro, PRAP-1, a Fab-fragment of a polyclonal antibody against human PAI-1, was shown to inhibit PAI-1 activity in rat plasma as well as to stimulate clot-lysis of the euglobulin fraction derived from rat plasma. Endotoxin administered to anaesthetised rats produced a marked increase in plasma PAI-1 activity. To study fibrin formation and lysis in vivo after intravenous (i. v.) injection of the coagulant enzyme batroxobin, 125I-fibrinogen was administered to the animals. The thrombi formed by batroxobin were rapidly lysed in control animals, while the rate of lysis was markedly attenuated in rats given endotoxin. PRAP-1 was administered i.v. (bolus + infusion) to rats given endotoxin and batroxobin and the PAI-1 inhibitor caused a dose-dependent decrease in the 125I-fibrin deposition in the lungs. An immunohistochemical technique was used to confirm this decrease in density of fibrin clots in the tissue. Furthermore, PRAP-1 decreased plasma PAI-1 activity in the rats and this reduction was correlated to the decrease in lung 125I-fibrin deposition at the corresponding time point. It is concluded that in this experimental model the PAI-1 antibody PRAP-1 may indeed inhibit thrombosis in animals exposed to endotoxin.

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