scholarly journals Role of plasminogen activator inhibitor-1 in promoting fibrin deposition in rabbits infused with ancrod or thrombin

Blood ◽  
1993 ◽  
Vol 82 (12) ◽  
pp. 3631-3636 ◽  
Author(s):  
C Krishnamurti ◽  
C Bolan ◽  
CA Colleton ◽  
TM Reilly ◽  
BM Alving
Keyword(s):  
Plasminogen Activator ◽  
Plasminogen Activator Inhibitor ◽  
Fibrin Deposition ◽  
Plasminogen Activator Inhibitor 1 ◽  
Elevated Activity ◽  
Activator Inhibitor ◽  
Pai 1

Abstract The role of defective fibrinolysis caused by elevated activity of plasminogen activator inhibitor-1 (PAI-1) in promoting fibrin deposition in vivo has not been well established. The present study compared the efficacy of thrombin or ancrod, a venom-derived enzyme that clots fibrinogen, to induce fibrin formation in rabbits with elevated PAI-1 levels. One set of male New Zealand rabbits received intravenous endotoxin to increase endogenous PAI-1 activity followed by a 1-hour infusion of ancrod or thrombin; another set of normal rabbits received intravenous human recombinant PAI-1 (rPAI-1) during an infusion of ancrod or thrombin. Thirty minutes after the end of the infusion, renal fibrin deposition was assessed by histopathology. Animals receiving endotoxin, rPAI-1, ancrod, or thrombin alone did not develop renal thrombi. All endotoxin-treated rabbits developed fibrin deposition when infused with ancrod (n = 4) or thrombin (n = 6). Fibrin deposition occurred in 7 of 7 rabbits receiving both rPAI-1 and ancrod and in only 1 of 6 receiving rPAI-1 and thrombin (P “ .01). In vitro, thrombin but not ancrod was inactivated by normal rabbit plasma and by purified antithrombin III or thrombomodulin. The data indicate that elevated levels of PAI-1 promote fibrin deposition in rabbits infused with ancrod but not with thrombin. In endotoxin-treated rabbits, fibrin deposition that occurs with thrombin infusion may be caused by decreased inhibition of procoagulant activity and not increased PAI-1 activity.

scholarly journals Role of plasminogen activator inhibitor-1 in promoting fibrin deposition in rabbits infused with ancrod or thrombin

Blood ◽  
1993 ◽  
Vol 82 (12) ◽  
pp. 3631-3636 ◽  
Author(s):  
C Krishnamurti ◽  
C Bolan ◽  
CA Colleton ◽  
TM Reilly ◽  
BM Alving
Keyword(s):  
Plasminogen Activator ◽  
Plasminogen Activator Inhibitor ◽  
Fibrin Deposition ◽  
Plasminogen Activator Inhibitor 1 ◽  
Elevated Activity ◽  
Activator Inhibitor ◽  
Pai 1

The role of defective fibrinolysis caused by elevated activity of plasminogen activator inhibitor-1 (PAI-1) in promoting fibrin deposition in vivo has not been well established. The present study compared the efficacy of thrombin or ancrod, a venom-derived enzyme that clots fibrinogen, to induce fibrin formation in rabbits with elevated PAI-1 levels. One set of male New Zealand rabbits received intravenous endotoxin to increase endogenous PAI-1 activity followed by a 1-hour infusion of ancrod or thrombin; another set of normal rabbits received intravenous human recombinant PAI-1 (rPAI-1) during an infusion of ancrod or thrombin. Thirty minutes after the end of the infusion, renal fibrin deposition was assessed by histopathology. Animals receiving endotoxin, rPAI-1, ancrod, or thrombin alone did not develop renal thrombi. All endotoxin-treated rabbits developed fibrin deposition when infused with ancrod (n = 4) or thrombin (n = 6). Fibrin deposition occurred in 7 of 7 rabbits receiving both rPAI-1 and ancrod and in only 1 of 6 receiving rPAI-1 and thrombin (P “ .01). In vitro, thrombin but not ancrod was inactivated by normal rabbit plasma and by purified antithrombin III or thrombomodulin. The data indicate that elevated levels of PAI-1 promote fibrin deposition in rabbits infused with ancrod but not with thrombin. In endotoxin-treated rabbits, fibrin deposition that occurs with thrombin infusion may be caused by decreased inhibition of procoagulant activity and not increased PAI-1 activity.

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

1993 ◽  
Vol 70 (02) ◽  
pp. 301-306 ◽  
Author(s):  
Linda A Robbie ◽  
Nuala A Booth ◽  
Alison M Croll ◽  
Bruce Bennett
Keyword(s):  
Plasminogen Activator ◽  
Plasminogen Activator Inhibitor ◽  
Fibrin Clot ◽  
Clot Lysis ◽  
Plasminogen Activator Inhibitor 1 ◽  
Dependent Inhibition ◽  
Activator Inhibitor ◽  
Pai 1

SummaryThe relative importance of the two major inhibitors of fibrinolysis, α2-antiplasmin (α2-AP) and plasminogen activator inhibitor (PAI-1), were investigated using a simple microtitre plate system to study fibrin clot lysis in vitro. Cross-linked fibrin clots contained plasminogen and tissue plasminogen activator (t-PA) at concentrations close to physiological. Purified α2-AP and PAI-1 caused dose-dependent inhibition. All the inhibition due to normal plasma, either platelet-rich or poor, was neutralised only by antibodies to α2-AP. Isolated platelets, at a final concentration similar to that in blood, 2.5 × 108/ml, markedly inhibited clot lysis. This inhibition was neutralised only by antibodies to PAI-1. At the normal circulating ratio of plasma to platelets, α2-AP was the dominant inhibitor. When the platelet:plasma ratio was raised some 20-fold, platelet PAI-1 provided a significant contribution. High local concentrations of PAI-1 do occur in thrombi in vivo, indicating a role for PAI-1, complementary to that of α2-AP, in such situations.

Impairment of adipose tissue development by hypoxia is not mediated by plasminogen activator inhibitor-1

2006 ◽  
Vol 95 (01) ◽  
pp. 174-181 ◽  
Author(s):  
Fabrizio Semeraro ◽  
Gabor Voros ◽  
Désiré Collen ◽  
H. Lijnen
Keyword(s):  
Adipose Tissue ◽  
Plasminogen Activator ◽  
Plasminogen Activator Inhibitor ◽  
Tissue Development ◽  
Plasminogen Activator Inhibitor 1 ◽  
Adipose Tissue Development ◽  
Activator Inhibitor ◽  
Pai 1

SummaryHypoxia in rodents and humans is associated with a reduction of body fat on the one hand, and with enhanced expression of plasminogen activator inhibitor-1 (PAI-1), the main inhibitor of the fibrinolytic system, on the other hand. It was the objective of this study to investigate whether impairment of adipose tissue development by hypoxia may be mediated by PAI-1. Five week old male wild-type (WT) C57Bl/6 mice were fed a standard (SFD) or high fat (HFD) diet and kept under normoxic or hypoxic (10% O2) conditions. In addition, PAI-1 deficient mice and WT littermates were kept on HFD under normoxia or hypoxia. In vitro, the effect of hypoxia (2% O2) was investigated on differentiation of 3T3-L1 cells into adipocytes. Hypoxia induced a significant reduction of weight gain in WT mice on either SFD or HFD, accompanied by lower weights of subcutaneous (SC) and gonadal (GON) fat. Under hypoxic conditions, adipocytes in the adipose tissues were significantly smaller, whereas blood vessel size and density were larger. Serum PAI-1 levels were enhanced in hypoxic mice on SFD but not on HFD, and overall did not correlate with the observed changes in adipose tissue composition. Furthermore, the effects of hypoxia on adipose tissue in mice on HFD were not affected by deficiency of PAI-1. The inhibiting effect of hypoxia on in vitro preadipocyte differentiation was not mediated by PAI-1 activity. In conclusion, impairment of in vivo adipose tissue development and in vitro differentiation of preadipocytes by hypoxia is not mediated by PAI-1.

scholarly journals The pharmacokinetics of plasminogen activator inhibitor-1 in the rabbit

Blood ◽  
1990 ◽  
Vol 76 (8) ◽  
pp. 1514-1520 ◽  
Author(s):  
EJ Mayer ◽  
T Fujita ◽  
SJ Gardell ◽  
RJ Shebuski ◽  
CF Reilly
Keyword(s):  
Plasminogen Activator ◽  
Expression System ◽  
Plasminogen Activator Inhibitor ◽  
Bolus Administration ◽  
Plasminogen Activator Inhibitor 1 ◽  
Main Site ◽  
Activator Inhibitor ◽  
Pai 1

Abstract The pharmacokinetics of the activated and latent forms of plasminogen activator inhibitor-1 (PAI–1) isolated from HT1080 fibrosarcoma cells (HT1080 PAI-1) and a nonglycosylated form of human PAI-1 isolated from a yeast expression system (rPAI-1) were followed in the rabbit. As assessed by an immunologic assay specific for human PAI-1, guanidine HCI activated HT1080 PAI-1 and rPAI-1 entered the total plasma volume following intravenous bolus administration and exhibited a biphasic clearance pattern. The t1/2s of HT1080 PAI-1 for the initial and beta phases equalled 6.0 and 24.8 minutes, respectively. The t1/2s of rPAI-1 for the initial and beta phases equalled 8.8 and 34.0 minutes, respectively. Similar results were obtained by measuring PAI-1 activity in plasma and with trace amounts of 125I-rPAI-1, suggesting that the above pharmacokinetic behavior could also apply to endogenous PAI-1. The liver was the main site of rPAI-1 clearance. Unactivated, latent PAI-1 exhibited a very different pharmacokinetic profile. Over 80% of latent rPAI-1 cleared from the circulation within 10 minutes (t1/2 = 1.7 minutes). The difference in clearance behavior between activated and latent PAI-1 may be related to the ability of activated PAI-1, but not latent PAI-1, to rapidly form high-molecular-weight complexes with plasma binding factors which were observed in vitro and in vivo. Because PAI-1 could potentially tilt the fibrinolytic balance toward a prothrombotic state, its rapid clearance may represent an important control mechanism governing the circulating levels of this key component of the fibrinolytic pathway.

scholarly journals Plasminogen Activator Inhibitor-1 Secretion by Autophagy Contributes to Melanoma Resistance to Chemotherapy through Tumor Microenvironment Modulation

Cancers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1253
Author(s):  
Hong-Tai Tzeng ◽  
Jenq-Lin Yang ◽  
Yu-Ju Tseng ◽  
Chih-Hung Lee ◽  
Wei-Ju Chen ◽  
...  
Keyword(s):  
Plasminogen Activator ◽  
Intracellular Signaling ◽  
Therapeutic Efficacy ◽  
Specific Inhibitor ◽  
Plasminogen Activator Inhibitor ◽  
Plasminogen Activator Inhibitor 1 ◽  
Activator Inhibitor ◽  
Pai 1

Autophagy plays a crucial role in maintenance of cellular homeostasis via intracellular signaling pathways, lysosomal degradation of selective cargo and mediating protein secretion. Dysregulation of autophagy has been implicated in tumorigenesis, tumor progression, and resistance to therapy. However, the mechanism of autophagy-dependent secretion involved in the responsiveness to chemotherapy is poorly understood. In this study, we showed that mitoxantrone (MitoX), a chemotherapeutic agent used for treating various cancers but not melanoma, induced autophagy in melanoma cells in vitro and in vivo. We also found that plasminogen activator inhibitor (PAI)-1 secretion by MitoX-induced autophagy modulated the pro-tumoral microenvironment. Attenuation of PAI-1 activity using a specific inhibitor, tiplaxtinin (TPX), or by targeting the autophagy gene, Becn1, induced efficient antitumor immunity, thereby overcoming the resistance to MitoX in vivo. Of note, the therapeutic efficacy of TPX was abolished in MitoX-treated Becn1-defective tumors. Collectively, our results demonstrate that tumor autophagy-dependent PAI-1 secretion impairs the therapeutic efficacy of MitoX and highlight targeting of tumor autophagy or its secretory cargo, PAI-1, as a novel strategy to repurpose MitoX-based chemotherapy for melanoma treatment.

scholarly journals The pharmacokinetics of plasminogen activator inhibitor-1 in the rabbit

Blood ◽  
1990 ◽  
Vol 76 (8) ◽  
pp. 1514-1520
Author(s):  
EJ Mayer ◽  
T Fujita ◽  
SJ Gardell ◽  
RJ Shebuski ◽  
CF Reilly
Keyword(s):  
Plasminogen Activator ◽  
Expression System ◽  
Plasminogen Activator Inhibitor ◽  
Bolus Administration ◽  
Plasminogen Activator Inhibitor 1 ◽  
Main Site ◽  
Activator Inhibitor ◽  
Pai 1

The pharmacokinetics of the activated and latent forms of plasminogen activator inhibitor-1 (PAI–1) isolated from HT1080 fibrosarcoma cells (HT1080 PAI-1) and a nonglycosylated form of human PAI-1 isolated from a yeast expression system (rPAI-1) were followed in the rabbit. As assessed by an immunologic assay specific for human PAI-1, guanidine HCI activated HT1080 PAI-1 and rPAI-1 entered the total plasma volume following intravenous bolus administration and exhibited a biphasic clearance pattern. The t1/2s of HT1080 PAI-1 for the initial and beta phases equalled 6.0 and 24.8 minutes, respectively. The t1/2s of rPAI-1 for the initial and beta phases equalled 8.8 and 34.0 minutes, respectively. Similar results were obtained by measuring PAI-1 activity in plasma and with trace amounts of 125I-rPAI-1, suggesting that the above pharmacokinetic behavior could also apply to endogenous PAI-1. The liver was the main site of rPAI-1 clearance. Unactivated, latent PAI-1 exhibited a very different pharmacokinetic profile. Over 80% of latent rPAI-1 cleared from the circulation within 10 minutes (t1/2 = 1.7 minutes). The difference in clearance behavior between activated and latent PAI-1 may be related to the ability of activated PAI-1, but not latent PAI-1, to rapidly form high-molecular-weight complexes with plasma binding factors which were observed in vitro and in vivo. Because PAI-1 could potentially tilt the fibrinolytic balance toward a prothrombotic state, its rapid clearance may represent an important control mechanism governing the circulating levels of this key component of the fibrinolytic pathway.

scholarly journals Prevention of Renal Fibrin Deposition in Endotoxin-induced DIC through Inhibition of PAI-1

2000 ◽  
Vol 84 (07) ◽  
pp. 65-70 ◽  
Author(s):  
Ramón Montes ◽  
Paul Declerck ◽  
Alfonso Calvo ◽  
Marta Montes ◽  
José Hermida ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Plasminogen Activator ◽  
Disseminated Intravascular Coagulation ◽  
Plasminogen Activator Inhibitor ◽  
Control Group ◽  
Fibrin Deposition ◽  
Plasminogen Activator Inhibitor 1 ◽  
Activator Inhibitor ◽  
Pai 1

SummaryPlasminogen activator inhibitor-1 (PAI-1) increases in endotoxemia thus possibly cooperating in altering the hemostatic balance in a prothrombotic direction. The effect of the inhibition of PAI-1 with the monoclonal antibody MA-33B8 was studied systemically and in kidneys in a lapine model of endotoxin-induced disseminated intravascular coagulation (DIC). The increase in plasmatic PAI activity in the control group (n = 9) was inhibited in the MA-33B8 treated rabbits (n = 5). Control rabbits showed renal fibrin deposits, whereas only one of the MA-33B8 rabbits did so. These results were confirmed immunohistochemically in kidneys as PAI-1 immunostaining was seen inside the glomeruli and larger vessels in the control group, whereas MA-33B8 rabbits showed a remarkable decrease, demonstrating that MA-33B8 successfully inhibited PAI-1 in the kidneys as well. Therefore evidence for the important role of PAI-1 in fibrin generation in endotoxin-induced DIC is presented, suggesting that strategies aiming at its reduction can be useful in this pathology.

scholarly journals Platelets inhibit fibrinolysis in vitro by both plasminogen activator inhibitor-1-dependent and -independent mechanisms

Blood ◽  
1994 ◽  
Vol 83 (2) ◽  
pp. 351-356 ◽  
Author(s):  
WP Fay ◽  
DT Eitzman ◽  
AD Shapiro ◽  
EL Madison ◽  
D Ginsburg
Keyword(s):  
Plasminogen Activator ◽  
Plasminogen Activator Inhibitor ◽  
Tissue Type ◽  
Clot Lysis ◽  
Homozygous Mutation ◽  
Plasminogen Activator Inhibitor 1 ◽  
Activator Inhibitor ◽  
Pai 1

Abstract Platelet-rich thrombi are resistant to lysis by tissue-type plasminogen activator (t-PA). Although platelet alpha-granules contain plasminogen activator inhibitor-1 (PAI-1), a fast-acting inhibitor of t-PA, the contribution of PAI-1 to the antifibrinolytic effect of platelets has remained a subject of controversy. We recently reported a patient with a homozygous mutation within the PAI-1 gene that results in complete loss of PAI-1 expression. Platelets from this individual constitute a unique reagent with which to probe the role of platelet PAI-1 in the regulation of fibrinolysis. The effects of PAI-1-deficient platelets were compared with those of normal platelets in an in vitro clot lysis assay. Although the incorporation of PAI-1-deficient platelets into clots resulted in a moderate inhibition of t-PA-mediated fibrinolysis, normal platelets markedly inhibited clot lysis under the same conditions. However, no difference between PAI-1-deficient platelets and platelets with normal PAI-1 content was observed when streptokinase or a PAI-1-resistant t-PA mutant were used to initiate fibrinolysis. In addition, PAI-1-resistant t-PA was significantly more efficient in lysing clots containing normal platelets than wild-type t-PA. We conclude that platelets inhibit t-PA-mediated fibrinolysis by both PAI- 1-dependent and PAI-1-independent mechanisms. These results have important implications for the role of PAI-1 in the resistance of platelet-rich thrombi to lysis in vivo.

scholarly journals Platelets inhibit fibrinolysis in vitro by both plasminogen activator inhibitor-1-dependent and -independent mechanisms

Blood ◽  
1994 ◽  
Vol 83 (2) ◽  
pp. 351-356 ◽  
Author(s):  
WP Fay ◽  
DT Eitzman ◽  
AD Shapiro ◽  
EL Madison ◽  
D Ginsburg
Keyword(s):  
Plasminogen Activator ◽  
Plasminogen Activator Inhibitor ◽  
Tissue Type ◽  
Clot Lysis ◽  
Homozygous Mutation ◽  
Plasminogen Activator Inhibitor 1 ◽  
Activator Inhibitor ◽  
Pai 1

Platelet-rich thrombi are resistant to lysis by tissue-type plasminogen activator (t-PA). Although platelet alpha-granules contain plasminogen activator inhibitor-1 (PAI-1), a fast-acting inhibitor of t-PA, the contribution of PAI-1 to the antifibrinolytic effect of platelets has remained a subject of controversy. We recently reported a patient with a homozygous mutation within the PAI-1 gene that results in complete loss of PAI-1 expression. Platelets from this individual constitute a unique reagent with which to probe the role of platelet PAI-1 in the regulation of fibrinolysis. The effects of PAI-1-deficient platelets were compared with those of normal platelets in an in vitro clot lysis assay. Although the incorporation of PAI-1-deficient platelets into clots resulted in a moderate inhibition of t-PA-mediated fibrinolysis, normal platelets markedly inhibited clot lysis under the same conditions. However, no difference between PAI-1-deficient platelets and platelets with normal PAI-1 content was observed when streptokinase or a PAI-1-resistant t-PA mutant were used to initiate fibrinolysis. In addition, PAI-1-resistant t-PA was significantly more efficient in lysing clots containing normal platelets than wild-type t-PA. We conclude that platelets inhibit t-PA-mediated fibrinolysis by both PAI- 1-dependent and PAI-1-independent mechanisms. These results have important implications for the role of PAI-1 in the resistance of platelet-rich thrombi to lysis in vivo.

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