The Roles of α2-Antiplasmin and Plasminogen Activator Inhibitor 1 (PAI-1) in the Inhibition of Clot Lysis

Robbie, Linda A.; Booth, Nuala A.; Croll, A.; Bennett, Bruce

doi:10.1055/s-0038-1649570

Cited by 71 publications

(60 citation statements)

References 22 publications

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“…We subsequently showed that, in the marrow of normal individuals, there were significant amounts of t-PA activity present, whereas in the marrow from patients with acute myeloid leukaemia, the PA was not t-PA, but u-PA (McWilliam et al, 1996(McWilliam et al, , 1998. Scherrer et al (1999) have recently shown that blast cells in acute myeloid leukaemia contain mRNAs for not only u-PA, but, in some types, for u-PAR, PAI-1 and PAI-2 also. None of the above studies, although they detected u-PA, directly examined the ability of leukaemic cells to lyse fibrin deposits, as they all depended upon ex vivo manipulation of the blood to separate plasminogen activators from their inhibitors prior to demonstrating the activity.…”

Section: Discussionmentioning

confidence: 93%

“…It has subsequently been demonstrated that normal bone marrow possesses considerable plasminogen-activating activity, largely because of t-PA (McWilliam et al, 1996), whereas marrow from patients with myeloid forms of acute leukaemia contains u-PA detectable both functionally and immunologically (McWilliam et al, 1998). Scherrer et al (1999) have confirmed the finding of u-PA antigen in leukaemic cells and have shown that they contain the u-PA receptor, u-PAR, in addition. The present study was undertaken to determine whether leukaemic blast cells contain sufficient quantities of plasminogen activator themselves to produce lysis of fibrin, and whether this is a property of APL blasts alone or is also present in other myeloid or non-myeloid forms of leukaemia.…”

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confidence: 76%

“…A microtitre-plate clot-lysis assay (Robbie et al, 1993) was used to examine and compare the lytic characteristics of cells isolated from leukaemic patients. Clots were prepared with the reagents at the following final concentrations in the microtitre wells: 2´94 mmol/l fibrinogen, 0´24 mmol/l plasminogen, 0´4 U/ml thrombin and 5´3 mmol/l CaCl 2 .…”

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confidence: 99%

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Myeloid leukaemic cells can lyse fibrin directly

et al. 2000

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Summary. Purified preparations of circulating leukaemic blast cells from patients with acute myeloid (M1±7) or acute lymphoblastic leukaemia, and the myeloid or lymphoid cells from patients with chronic myeloid or lymphocytic forms of leukaemia, were incorporated into clots prepared from fibrinogen and plasminogen. Patterns of lysis were followed and measured by light transmission in a microtitre plate reader. Mature polymorphonuclear and mononuclear cell fractions from normal individuals were studied concurrently for comparison. Blast cells from the myeloid forms of acute leukaemia (M2±4) and`myeloid' cell fractions from patients with chronic myeloid leukaemia were capable of lysing plasminogen-containing clots; this activity was neutralized by addition of immunoglobulin against urokinase plasminogen activator (u-PA), but not by anti-tissue plasmogen activator (t-PA). Mature polymorphonuclear and mononuclear cells from normal individuals lacked lytic activity, as did the leukaemic cells from patients with acute lymphoblastic or chronic lymphocytic leukaemia. Lysed blast cells showed the presence of free plasminogen activator on sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS±PAGE) with overlay zymography, also neutralized by anti-u-PA, whereas normal polymorphonuclear and mononuclear cells did not. These observations suggest that mechanisms underlying some forms of severe bleeding in acute myeloid leukaemias have a critical fibrinolytic component generated by the blast cells themselves.

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Section: Discussionmentioning

confidence: 93%

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confidence: 76%

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Myeloid leukaemic cells can lyse fibrin directly

et al. 2000

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“…Human fibrinogen (FGN) was from Sigma (St. Louis, MO). Human plasminogen (PLG) was isolated from plasma (Stewart Regional Blood Center, Tyler, TX) using affinity chromatography on lysine-sepharose 4B beads [19]. The PLG preparation was homogenous and appeared on a Coomassie-stained gel as a doublet with apparent molecular weights corresponding to Glu-and Lys-forms of PLG, confirming that the preparation was highly purified and consisted of these two forms.…”

Section: Reagentsmentioning

confidence: 96%

Thrombin–thrombomodulin inhibits prourokinase-mediated pleural mesothelial cell-dependent fibrinolysis

Iakhiaev

Nalian

Koenig

et al. 2007

Thrombosis Research

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SummaryFibrin deposition is a hallmark of pleural inflammation and loculation but understanding of mechanisms by which mesothelial cells regulate intrapleural fibrinolysins remains incomplete. We speculated that pleural mesothelial cells regulate local fibrinolytic capacity via processing of single chain urokinase type plasminogen activator (scuPA). Pretreatment of human pleural mesothelial (MeT-5A) cells with TGF-β or thrombin, either alone or in combination, inhibited urokinase (uPA)-mediated fibrinolysis by MeT-5A. Thrombin, unlike TGF-β, inhibited fibrinolysis without induction of PAI-1, suggesting that thrombin-mediated cleavage of scuPA inhibits the fibrinolytic capacity of MeT-5A cells. Thrombin cleaves both purified scuPA as well as that secreted by MeT-5A cells and cell surface thrombomodulin accelerates thrombin-mediated cleavage of scuPA to inhibit cellular fibrinolytic activity. Molecular dynamics analyses demonstrated that thrombin-cleaved scuPA (uPAt) do not acquire a catalytically active conformation and that secondary plasminogen binding sites of uPA implicated in plasminogen activation are distorted in uPAt, explaining, at least in part, why uPAt is a poor enzyme. uPAt was detectable in transudative and exudative pleural effusions from patients. Intrapleural administration of scuPA generated increased levels of uPAt in PF of rabbits with pleural injury and loculation induced by tetracycline in vivo. This pathway is operative in diverse forms of pleural injury, restricts the urokinase-dependent fibrinolytic capacity of pleural mesothelial cells and contributes to local control of fibrinolytic activity via processing of endogenous or exogenous scuPA within the pleural compartment. Keywords fibrinolysis; single chain urokinase type plasminogen activator (scuPA); thrombin; thrombomodulin Fibrin deposition in the pleural space is a hallmark of inflammatory pleural disease [1,2]. Fibrin is deposited as a result of excessive activation of coagulation and insufficient fibrinolysis. Under physiological conditions, coagulation and fibrinolysis are precisely regulated and molecular links between these systems permit timely removal of ongoing or acutely induced fibrin deposits [3,4]. The major fibrinolytic protease -plasmin, is generated by activation of plasminogen (PLG) by both tissue type PLG activator (tPA) as well as by urokinase (uPA) [5,6,7]. Plasmin cleaves both tPA and uPA, transforming them from single chain forms to more Please address all correspondence to: Alexei Iakhiaev Ph.D., Assistant Professor of Biochemistry, The University of Texas Health Center at Tyler, 11937 US HWY 271, Tyler, TX 75708, Telephone: (903) FAX: (903) 877-5627, Email: alexei.iakhiaev@uthct.edu. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable for...

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“…This effect is enhanced if the clot is protected from tissue plasminogen activatorinduced fibrinolysis. In several studies it has been shown that PAI-1 protects fibrin clots from tPA-mediated plasmin degradation in a dose-dependent manner (6)(7)(8)(9)(10)(11).…”

Section: Introductionmentioning

confidence: 99%

Highly stable plasminogen activator inhibitor type one (VLHL PAI-1) protects fibrin clots from tissue plasminogen activator-mediated fibrinolysis

Jankun¹,

Aleem²,

Selman³

et al. 2007

Int J Mol Med

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Abstract. Plasminogen activator inhibitor-1 (PAI-1) is the major specific inhibitor of tissue-type plasminogen activator (tPA) which mediates fibrin clot lysis through activation of plasminogen. Wild-type-PAI-1 (wPAI-1) is rapidly converted to the latent form (half-life of ~2 h) and loses its ability to inhibit tPA. We developed a very long half-life PAI-1 (VLHL PAI-1), a recombinant protein with a half-life >700 h compared with wPAI-1. In this study, VLHL PAI-1 was assessed for its ability to inhibit clot lysis in vitro. Clot formation was initiated in normal plasma supplemented with tPA by the addition of either tissue factor or human recombinant FVIIa. Clot lysis time, monitored turbidimetrically in a microtiter plate reader, was determined at various concentrations of wPAI-1 and VLHL PAI-1. Both wPAI-1 and VLHL PAI-1 caused a significant increase in clot lysis time, although the latter was somewhat less effective at lower concentrations. The VLHL PAI-1, but not wPAI-1, maintained its anti-fibrinolytic activity after preincubation overnight at 37˚C. These studies demonstrate that VLHL PAI-1 is an effective inhibitor of fibrin clot degradation. Due to the high stability of VLHL PAI-1 compared with wPAI-1, this novel inhibitor of tPA-mediated fibrinolysis may have therapeutic applications for treating surgical and trauma patients when used directly or in conjunction with the procoagulant recombinant FVIIa.

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The Roles of α2-Antiplasmin and Plasminogen Activator Inhibitor 1 (PAI-1) in the Inhibition of Clot Lysis

Cited by 71 publications

References 22 publications

Myeloid leukaemic cells can lyse fibrin directly

Myeloid leukaemic cells can lyse fibrin directly

Thrombin–thrombomodulin inhibits prourokinase-mediated pleural mesothelial cell-dependent fibrinolysis

Highly stable plasminogen activator inhibitor type one (VLHL PAI-1) protects fibrin clots from tissue plasminogen activator-mediated fibrinolysis

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