Platelet protease-activated receptor 1 and membrane expression of P-selectin in pulmonary arterial hypertension

Introduction

Pulmonary arterial hypertension (PAH) is frequently associated with thrombotic events, particularly involving the pulmonary microcirculation at sites of vascular injury. We therefore decided to analyse protease-activated receptor 1 (PAR1), a key element in the activation of human platelets by thrombin, in PAH patients in stable clinical condition.

Methods

Using flow cytometry, we analyzed platelet PAR1 density, PAR1-mediated exposure of P-selectin and the formation of platelet-leukocyte aggregates in 30 PAH patients aged 11 to 78 years (median 50.5 years). The control group consisted of 25 healthy subjects with the same age range as patients.

Results

In patients, total platelet PAR1 density and uncleaved PAR1 density correlated negatively with platelet count (r² = 0.33 and r² = 0.34 respectively, p < 0.0015). In patients with a low platelet count (< 150 × 10⁹ platelets/L), both densities were increased relative to controls (82% and 33% respectively, p < 0.05). Thrombin peptide-induced platelet exposure of P-selectin was directly related to total and uncleaved PAR1 density (respectively, r² = 0.33 and r² = 0.29, p < 0.0025) and increased in subjects with low platelet count (46% versus those with normal platelet count, p < 0.05). Patients with low platelet count had decreased in vitro thrombin-induced formation of platelet-leukocyte aggregates (57% decrease versus controls, p < 0.05).

Conclusions

There seems to be a subpopulation of PAH patients with increased propensity to thrombotic events as suggested by increased platelet PAR1 expression and PAR-mediated surface exposure of P-selectin associated with decreased platelet count.     

Release reaction of brain-derived neurotrophic factor (BDNF) through PAR1 activation and its two distinct pools in human platelets

Brain-derived neurotrophic factor (BDNF) is a cytokine that plays important roles in the survival, development, and plasticity of neurons. BDNF is also expressed in peripheral tissues and cells. In this article, we report the BDNF release reaction through thrombin stimulation and its localization in human platelets.Platelets from healthy volunteers were subjected to PAR1-AP or PAR4-AP stimulation. Release of BDNF was measured by ELISA. Localization of BDNF in resting and thrombin-activated platelets was examined by immunoelectron microscopy and sucrose gradient ultracentrifugation following western blotting.BDNF was released dose-dependently with PAR1-AP concentrations with drastic release at low PAR1-AP concentrations and gently release at high PAR1-AP concentrations. Maximum BDNF release was approximately 37% at 132 μM PAR1-AP. In contrast, 3.8% BDNF was released with 1.13 mM PAR4-AP stimulation. In immunoelectron microscopy and sucrose gradient ultracentrifugation analyses, BDNF was detected not only in α-granules but also cytoplasm in of the resting platelets, and it was distributed in the swollen open canalicular system fused to α-granules at 1 min and disappeared at 5 min after stimulation by thrombin. However, BDNF in cytoplasm remained throughout platelet activation.In conclusions, we demonstrate that BDNF is released from platelets through predominately PAR1 regulation. Furthermore, we identified two pools of BDNF in the α-granules and cytoplasm of human platelets, and only BDNF in α-granules is released through platelet activation.     

Antithrombotic effects of PAR1 and PAR4 antagonists evaluated under flow and static conditions

Introduction

Thrombin-mediated activation of human platelets involves the G-protein-coupled protease-activated receptors PAR1 and PAR4. Inhibition of PAR1 and/or PAR4 is thought to modulate platelet activation and subsequent procoagulant reactions. However, the antithrombotic effects of PAR1 and PAR4 antagonism have not been fully elucidated, particularly under flow conditions.

Materials and Methods

A microchip-based flow chamber system was used to evaluate the influence of SCH79797 (PAR1 antagonist) and YD-3 (PAR4 antagonist) on thrombus formation mediated by collagen and tissue thromboplastin at shear rates simulating those experienced in small- to medium-sized arteries (600 s^- 1) and large arteries and small veins (240 s^- 1).

Results

At a shear rate of 600 s^- 1, SCH79797 (10 μM) efficiently reduced fibrin-rich platelet thrombi and significantly delayed occlusion of the flow chamber capillary (1.44 fold of control; P < 0.001). The inhibitory activity of SCH79797 was diminished at 240 s^- 1. YD-3 (20 μM) had no significant effect at either shear rate. The antithrombotic effects of SCH79797 were significantly augmented when combined with aspirin and AR-C66096 (P2Y₁₂ antagonist), but not with YD-3. In contrast, no significant inhibition of tissue factor-induced clot formation under static conditions was observed in blood treated with SCH79797 and YD-3, although thrombin generation in platelet-rich plasma was weakly delayed by these antagonists.

Conclusions

Our results suggest that the antithrombotic activities of PAR1 and/or PAR4 antagonism is influenced by shear conditions as well as by combined platelet inhibition with aspirin and a P2Y₁₂-antagonist.     

Activated inflammatory cells participate in thrombus size through tissue factor and plasminogen activator inhibitor-1 in acute coronary syndrome: Immunohistochemical analysis

Introduction

Recent studies have suggested that circulating inflammatory cells augment the growth of thrombus in acute coronary syndrome (ACS). We therefore immunohistochemically analyzed thrombi in aspirates obtained from patients immediately after the onset of ACS.

Materials and Methods

Two hundred twenty samples were studied. Total thrombus area, white thrombus area, and red thrombus area were measured. As antibodies in immunohistochemical staining, myeloperoxidase (MPO), CD66b, CD68, p-selectin, tissue factor (TF) and PAI-1were employed respectively.

Results

The ratios of areas of red and white thrombi correlated with whole sample areas of enlarged thrombi (r = 0.48, p < 0.001). The immunohistochemical findings revealed granulocytes and macrophages aggregated around p-selectin-positive platelets that shared the boundary between white and red thrombi, a region where MPO and CD66b expression was abundant in neutrophils. The ratios (%) of MPO- and CD66b-positive cells significantly correlated with whole sample areas (r = 0.50; p < 0.001 and r = 0.49; p < 0.001, respectively). Neutrophils and macrophages within thrombi were positive for TF and PAI-1. Along the boundary between red and white thrombi, TF and PAI-1 positivity coincided with MPO-, CD66b- and CD68-positive cells. The ratios of cells positive for both TF and PAI-1 in this area significantly correlated with the whole sample area (r = 0.43, p < 0.001 and r = 0.60, p < 0.001, respectively).

Conclusions

These results suggested that enhanced activation of peripheral neutrophils together with increased TF and PAI-1 expression might comprise a considerable portion of thrombus enlargement.     

Compartment-specific expression of plasminogen activator inhibitor-1 correlates with severity/outcome of murine polymicrobial sepsis

Introduction

Plasminogen activator inhibitor type 1 (PAI-1) co-induces septic coagulopathy. We aimed to characterize spatiotemporal PAI-1 gene/protein changes occurring in acute sepsis and tested whether PAI-1 fluctuations correlate with sepsis severity and early outcome.

Materials and Methods

Female mice underwent cecal ligation and puncture (CLP) in three experiments. I: mild (23G needle) CLP to compare circulating PAI-1 to its organ gene expression within 0-24 h. II: mild or severe (17G) CLP to asses differences in PAI-1 organ-specific expression and in coagulation/fibrinolysis. III: moderate (18G) CLP to characterize circulating PAI-1 in survivors (SUR), and to retrospectively compare it to dying (DIE) mice.

Results

In mild sepsis, the trajectory of circulating PAI-1 (1089 ng/ml peak at 24 h) was identical to PAI-1 gene expression in the left cranial vena cava (LCVC; 39-fold peak at 24 h). PAI-1 expression rise was immediate (60-fold at 6 h) and sustained in the liver, but marginal in the kidney, lungs and heart. Body temperature decrease correlated with the PAI-1 expression increase in the liver (rho = − 0.79), and blood (protein, rho = − 0.53). Regardless of severity, PAI-1 gene expression remained unaltered except the LCVC where it was > 3-fold higher in 17G (vs. 23G). Severe sepsis extended activated partial thromboplastin/pro-thrombin time and increased circulating PAI-1, while antithrombin and fibrinogen decreased at 6 and/or 24 h (vs. 23G). Within 24 h of death, circulating PAI-1 in DIE was > 3-fold higher versus SUR.

Conclusions

Polymicrobial sepsis caused a gradual circulating PAI-1 release and highly variable gene expression response pattern in organs. Only circulating PAI-1 and PAI-1 expression in the LCVC correlated with response severity and/or outcome.     

Effects of carvedilol or metoprolol on PAI-1, tPA-mass concentration or Von Willebrand factor in chronic heart failure - a COMET substudy

Introduction

In COMET (Carvedilol or Metoprolol European Trial), carvedilol reduced mortality compared with metoprolol in patients with chronic heart failure. We hypothesized that carvedilol might have greater effects on endothelial derived haemostatic factors than metoprolol. We aimed to study the effects of carvedilol or metoprolol on tissue plasminogen activator (tPA), its inhibitor PAI-1 and Von Willebrand factor (VWF) in patients with heart failure.

Material and Methods

We recruited 260 patients (134 on carvedilol, 126 on metoprolol), mean age 66 years and 84% of them men. Plasma mass concentrations of tPA and PAI-1and percent of VWF were measured at baseline and after one and two years of treatment.

Results

Plasma tPA, PAI-1 and VWF were similar between treatment groups at baseline and no significant differences between groups emerged after one or two years of treatment. In paired analyses in patients assigned to carvedilol, median PAI-1 level decreased from 37.2 to 32.1 µg/l at two years (p = 0.034) and of VWF decreased from baseline to one year (240 vs. 218%, p = 0.023) in patients assigned to carvedilol but were not reduced at any time in patients assigned to metoprolol. Plasma tPA increased over time in both treatment groups (p = 0.013 and 0.027 respectively).

Conclusion

We found no significant difference in the effects of carvedilol or metoprolol on tPA, PAI-1 and VWF. Comparison over time within treatment groups suggested that PAI-1 and VWF might have declined on carvedilol but not on metoprolol. Our hypothesis is not proved but this may reflect an inadequate sample size rather than lack of an effect.     

Platelet PAR1 receptor density--correlation to platelet activation response and changes in exposure after platelet activation

INTRODUCTION: A polymorphism (-14 A/T) affecting PAR1 expression on the platelet surface has recently been identified. A two-fold variation in receptor density, which correlated with the platelet response to PAR1-activating peptide (PAR1-AP), has been reported. MATERIALS AND METHODS: We used flow cytometry to measure the correlation between the number of PAR1 receptors and platelet activation. We also measured the changes in receptor exposure after platelet activation with PAR1-AP, ADP, PAR4-AP or a collagen-related peptide (CRP). RESULTS: In our study, the PAR1 receptor number varied almost four-fold, from 547 to 2063 copies/platelet (mean+/-S.D. 1276+/-320, n=70). The number of PAR1 receptors on resting platelets correlated to platelet fibrinogen binding and P-selectin expression following platelet activation with PAR1-AP (r(2)=0.30, p<0.01 and r(2)=0.15, p<0.05, respectively, n=36). The correlation was not improved by exclusion of the ADP-component from the PAR1-AP-induced response. We found a trend, but no statistically significant differences in PAR1 receptor number and platelet reactivity between A/A individuals and T/A or T/T individuals. Ex vivo activation with PAR1-AP decreased PAR1 surface exposure to 71+/-19% of the exposure on resting platelets (mean+/-S.D., p<0.01, n=19), while activation by ADP, PAR4-AP or CRP significantly increased the exposure, to 151+/-27%, 120+/-21% and 138+/-25%, respectively (n=11, 11 and 10). CONCLUSIONS: This study shows a large variation in PAR1 receptor number in healthy individuals, a variation correlated to the platelet activation response. We found a significant reduction in PAR1 surface exposure after adding PAR1-AP, while activation with ADP, PAR4-AP or CRP increased the exposure.     

Physiological changes in membrane-expressed platelet factor 4: Implications in heparin-induced thrombocytopenia

Background

Many heparin-induced thrombocytopenia (HIT) antibodies cause platelet activation in the serotonin release assay (SRA) in the absence of heparin. This in vitro observation may help unravel the mechanism of delayed-onset HIT, where seropositive patients develop thrombocytopenia and associated thrombosis after cessation of heparin.

Objective

Studies were conducted to examine the relationship between platelet environment, surface PF4 expression, and the extent of heparin-independent platelet activation in the SRA.

Methods

Ex vivo platelets were washed and labeled for SRA, then used either before or after 45 minutes of recovery at 37 °C. HIT antibody-mediated serotonin release in the absence of heparin was compared to the extent of surface staining of the platelets with fluorescent anti-human PF4 antibodies.

Results

Handling of platelets for in vitro studies resulted in transient expression of surface PF4, and it was during this interval that platelets were most sensitive to activation by HIT antibodies in the absence of heparin. Heparin-independent platelet activation was attenuated when SRA-positive specimens were retested after platelets were incubated 45 minutes at 37 °C. Surface PF4 expression was diminished on the rested platelets, compared to the same platelets labeled immediately after handling. Thus compared to rested platelets, mildly activated platelets had elevated surface PF4 expression and a higher level of HIT antibody-mediated, heparin-independent platelet activation.

Conclusion

Surface expression of PF4 reflects HIT antigen presentation, and varies with the physiological state of platelets. Thus there can be differences in HIT antibody target availability among patients which may explain the variability in consequences of HIT antibody seropositivity.     

In vitro effects of detergent sclerosants on fibrinolytic enzymes and inhibitors

Objective

To investigate the effects of Sodium Tetradecyl Sulphate (STS) and Polidocanol (POL) on fibrinolytic mechanisms.

Materials and methods

Measurements were done with serial dilutions of sclerosants in whole blood (WB), platelet rich (PRP) and platelet poor plasma (PPP). Control experiments were done in 5% bovine serum albumin (BSA), spiked with the enzyme/inhibitor. Plasminogen was measured with a chromogenic assay. Alpha-2-antiplasmin (AP) activity, plasmin-alpha-2-antiplasmin (PAP) complexes, plasminogen activator inhibitor-1 (PAI-1) activity, tissue plasminogen activator (t-PA) total antigen, t-PA activity, t-PA/PAI-1 complexes, thrombin activatable fibrinolysis inhibitor (TAFI) antigen and activated TAFI (TAFIa) were measured by ELISA.

Results

At high concentrations (> 0.3%), STS destroyed plasminogen, PAI-1, t-PA/PAI-1 complexes and total t-PA antigen but increased t-PA activity. At low concentrations (< 0.3%), both agents reduced PAP complexes while increasing AP activity. Low concentration STS increased PAI-1 activity, t-PA/PAI-1 complexes, TAFI and TAFIa. Low concentration POL mildly increased the total t-PA antigen and TAFI.

Conclusion

At low concentrations, both agents demonstrated a prothrombotic, antifibrinolytic (increase in PAI-1, total t-PA antigen, AP, TAFI and TAFIa) activity. At high concentrations, STS demonstrated non-prothrombotic (destruction of PAI-1, t-PA/PAI-1 complexes), antifibrinolytic (destruction of plasminogen, increase in AP) activity while POL had minimal effect.     

Association of tissue plasminogen activator and plasminogen activator inhibitor polymorphism with myocardial infarction: A meta-analysis

Introduction

To investigate whether t-PA Alu repeat insertion/deletion (I/D) and PAI-1 4 G/5 G genetic variations are associated with the risk of MI.

Methods

We conducted a meta-analysis to assess the association between the t-PA I/D and PAI-1 4 G/5 G polymorphisms and risk of MI. We also performed subgroup analyses based on ethnicity (Caucasian, Asian, and African), gender and age. Forty one eligible studies including 12,461 cases and 14,993 controls were identified to evaluate the impact of PAI-1 4 G/5 G polymorphism on MI. Seven studies investigated the relationship between t-PA I/D and MI.

Results

This meta-analysis revealed that the PAI-1 4 G allele (4 G/4 G and 4 G/5 G genotype) was associated with an increased risk of MI compared with the 5 G allele in the overall population (OR = 1.094, 95% CI = 1.021 - 1.172, p = 0.011). The relative risks of MI for 4 G/4 G genotype was increased when compared to 5 G/5 G genotype and 5 G allele, with odds ratio at 1.157 (95% CI 1.015 - 1.320, p = 0.029) and 1.126 (95% CI = 1.015 - 1.249, p = 0.025). However, the results show that the 4 G/5 G polymorphism risk for MI was not associated with ethnicity stratification as Caucasian, Asian or African population. No substantial differences in the genotype distributions were observed in the MI group and control group along the lines of gender and age. After multivariable analysis t-PA I/D polymorphism showed no consistent association with MI.

Conclusions

This study suggests that the 4 G/5 G polymorphism of PAI-1 may be a risk factor for MI in overall populations.     

Sustained high plasma plasminogen activator inhibitor-1 levels are associated with severity and mortality in septic patients

Background

Higher plasma plasminogen activator inhibitor-1 (PAI-1) levels have been reported in septic patients. However, some questions remain unanswered, such as whether there is an association between plasma PAI-1 levels and sepsis severity and mortality, and inflammation state during the first week.

Methods

Multicenter, observational and prospective study carried out in six Spanish Intensive Care Units of 260 patients with severe sepsis. Circulating levels of PAI-1 and tumour necrosis factor (TNF)-α were measured at day 1, 4 and 8. End-point was 30-day mortality.

Results

Nonsurviving septic patients (n = 89) presented higher PAI-1 levels than surviving (n = 171) at day 1 (58.4 (33.3-83.8) vs 36.5 (21.1-62.5) ng/mL; p < 0.001), 4 (34.0 (14.7-53.3) vs 16.2 (10.2-27.4) ng/mL; p < 0.001) and 8 (30.6 (16.2-47.8) vs 18.9 (10.4-29.5) ng/mL; p = 0.004). We found a positive correlation of PAI-1 levels with SOFA, lactic acid, aPTT, INR and TNF-α, and negative with platelet count at day 1, 4 and 8. Logistic regression analyses showed that PAI-1 levels at day 1 (p < 0.001), 4 (p < 0.001) and 8 (p = 0.001) were associated with 30-day mortality. On ROC curve analysis to predict 30- day survival, the area under the curve of PAI-1 levels at day 1, 4 and 8 were 0.65 (95% CI = 0.58-0.72; p < 0.001), 0.69 (95% CI = 0.60-0.78; p < 0.001) and 0.65 (95% CI = 0.54-0.75; p = 0.005) respectively.

Conclusions

The most interesting findings of our study, to our knowledge the largest series reporting PAI-1 levels during follow-up in septic patients, were that plasma PAI-1 levels during the first week were associated with inflammation, severity and mortality.     

Asymmetric dimethylarginine impairs fibrinolytic activity in human umbilical vein endothelial cells via p38 MAPK and NF-κB pathways

Introduction

Asymmetric dimethylarginine (ADMA) is a potent endogenous inhibitor of nitric oxide (NO) synthase. An increased synthesis and/or a reduced catabolism of ADMA might contribute to the onset and progression of thrombosis. The present study was designed to evaluate the effect of ADMA on fibrinolytic factors in endothelial cells, and to investigate the cellular mechanisms.

Materials and Methods

Human umbilical vein endothelial cells (HUVECs) were treated with different concentrations of ADMA for various periods; Then HUVECs were preincubated with NO precursor (L-arginine), MAPK inhibitors, or NF-κB inhibitor (PDTC) before ADMA treatment to repeat the experiment. Protein levels of tissue plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1), and NF-κB activity were measured by ELISA; mRNA levels of tPA and PAI-1 were assayed by qRT-PCR; The activation of MAPK was characterized by western blot analysis.

Results

(1) ADMA decreased tPA antigen levels in time- and concentration-dependent manners, with the maximum effect of 30 μmol/L ADMA for 48 h (control 109.01 ± 4.15 ng/ml vs ADMA 86.76 ± 5.95 ng/ml, p < 0.01); (2) 30 μmol/L ADMA elevated antigen levels of PAI-1 in a time-dependent manner, with the maximum effect of 30 μmol/L ADMA for 48 h (control 2721.12 ± 278.02 ng/ml vs ADMA 3435.78 ± 22.33 ng/ml, p < 0.05); (3) ADMA reduced tPA mRNA levels and increased PAI-1 mRNA levels; (4) L-arginine, SB203580 (p38 MAPK inhibitor) and PDTC attenuated the effects of ADMA on tPA and PAI-1 significantly. (5) ADMA induced a rapid phosphorylation of p38 MAPK, and stimulated NF-κB activity greatly.

Conclusions

ADMA may accelerate thrombosis development by impairing fibrinolytic activity in vascular via inhibiting nitric oxide production and then activating its downstream p38 MAPK and NF-κB pathways.     

Impaired spontaneous thrombolytic activity measured by global thrombosis test in males with metabolic syndrome

Introduction

In patients with metabolic syndrome (MetS), activity of the fibrinolytic system is generally surmised to be decreased through increased plasminogen activator inhibitor-1 (PAI-1) generation. However, there have been no detailed reports describing whether the clot lysis activity is more dominant than increased clot formation activity for production of the thrombotic state in MetS.

Methods

The global thrombosis test (GTT) is a novel method designed to test both clot formation and clot lysis activities under physiological conditions by using non-anticoagulated blood samples in vitro. We used the GTT to examine the thrombotic or thrombolytic states in males with MetS.

Results

Lysis time, which reflects spontaneous clot lysis activity, was significantly longer in MetS subjects (median, 1494 s; range, 865-3596 s; n = 30) than in control subjects (median 1246 s; range, 667-2239 s; n = 53). There was no significant difference between the two groups in occlusion time, which reflects platelet function. The mean level of PAI-1 was significantly higher in MetS subjects than in controls (mean ± SE, 8.7 ± 1.1 and 5.0 ± 0.5 ng/mL, respectively). PAI-1 level and lysis time were significantly correlated (r = 0.400, P < 0.01).

Conclusion

These results suggest that male patients with MetS are more likely than controls to experience a thrombotic state through decreased fibrinolytic activity due to increased PAI-1 generation, and that the GTT is useful for evaluating fibrinolytic activity in vitro.     

The neutrophil serine protease PR3 induces shape change of platelets via the Rho/Rho kinase and Ca signaling pathways

Introduction

Proteinase 3 (PR3) is released from neutrophil azurophilic granules and exerts complex effects on the inflammatory process. PR3 catalyzes the degradation of a number of macromolecules, but the consequences on blood cells are less well defined. In the present study, the effect of PR3 on human platelets was thoroughly investigated.

Methods

The experiments were performed on washed platelets freshly isolated from blood donated by healthy human volunteers. Platelets shape change and aggregation was measured on a Chrono-Log aggregometer. The phosphorylated form of MYPT1 was visualized by immunostaining. Platelet activation was further evaluated by flow cytometry.

Results

PR3 induced platelet shape change but not aggregation. Flow cytometry analysis showed that PR3 induced no P-selectin expression or binding of fibrinogen to the platelets, and it did not change the activation in response to PAR1- or PAR4-activating peptides or to thrombin. Furthermore, Fura-2 measurement and immuno-blotting analysis, respectively, revealed that PR3 stimulated small intracellular Ca^2 + mobilization and Thr696-specific phosphorylation of the myosin phosphatase target subunit 1 (MYPT1). Separate treatment of platelets with the Rho/Rho kinase inhibitor Y-27632 and the intracellular Ca^2 + chelator BAPTA/AM reduced the shape change induced by PR3 whereas concurrent treatment completely inhibited it.

Conclusion

The data shows that the neutrophil protease PR3 is a direct modulator of human platelets and causes shape change through activation of the Rho/Rho kinase and Ca^2 + signaling pathways. This finding highlights an additional mechanism in the complex interplay between neutrophils and platelets.     

Ambient temperature affects thrombotic potential at rest and following exercise

Introduction

During exercise, ischemic risk increases, possibly due to changes in coagulation and fibrinolytic activity. Previous research suggests ambient temperature affects resting thrombotic potential, but the effect of heat and cold on hemostasis during exercise is unknown. The purpose of this study was to assess changes in coagulation and fibrinolysis during maximal exercise in hot and cold temperatures, and to compare those responses to exercise under temperate conditions.

Materials & Methods

Fifteen healthy men completed maximal exercise tests in hot (30 °C), temperate (20 °C) and cold (5° - 8 °C) temperatures. Blood samples were obtained before and immediately after exercise and analyzed for concentrations of thrombin-antithrombin III (TAT), active tissue plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1). Results were analyzed by ANOVA.

Results

A main effect of time was observed for TAT (temperate = 1.71 ± 0.82 - 2.61 ± 0.43 ng/ml, hot = 1.81 ± 0.73 - 2.62 ± 0.67 ng/ml, cold = 2.33 ± 0.65 - 2.89 ± 0.81 ng/ml, PRE to POST, respectively) and tPA activity (temperate = 0.72 ± 0.44 - 2.71 ± 0.55 IU/ml, hot = 0.72 ± 0.38 - 2.64 ± 0.61 IU/ml, cold = 0.86 ± 0.45 - 2.65 ± 0.77 IU/ml, PRE to POST, respectively). A trend was observed for the PAI-1 response to exercise (temperate = 14.5 ± 23.7 - 12.3 ± 20.2 IU/ml, hot = 15.1 ± 26.5 - 10.0 ± 15.1 IU/ml, cold = 10.5 ± 10.4 - 7.9 ± 9.7 IU/ml, PRE to POST, respectively, p = 0.08). TAT concentrations were significantly higher in cold compared to temperate and hot conditions.

Conclusion

Coagulation potential is elevated during exposure to cold temperatures. These data suggest that risk of an ischemic event may be elevated in the cold.     

Polymorphisms of PAI-1 and platelet GP Ia may associate with impairment of renal function and thrombocytopenia in Puumala hantavirus infection

Introduction

Puumala virus (PUUV) infection is a viral hemorrhagic fever with renal syndrome (HFRS) characterized by thrombocytopenia and acute impairment of renal function. We aimed to assess whether genetic polymorphisms of platelet antigens together with those of von Willebrand factor (VWF) and plasminogen activator inhibitor (PAI-1) correlate with disease severity.Patients and methods172 consecutive hospital-treated patients with serologically confirmed acute PUUV infection were included. Platelet glycoprotein (GP) IIIa T > C (rs5918), GP Ia T > C (rs1126643), GP Ib C > T (rs6065), GP VI T > C (rs1613662), VWF A > G (rs1063856) and PAI-1 A > G (rs2227631) were genotyped. The associations of the rarer alleles with variables reflecting the severity of the disease were analyzed.

Results

PAI-1 G-carriers had higher maximum creatinine level compared with the non-carriers (median 213 μmol/l, range 60-1499 μmol/l vs. median 122 μmol/l, range 51-1156 μmol/l, p = 0.01). The GG-genotypes had higher creatinine levels than GA- and AA-genotypes (medians 249 μmol/l, 204 μmol/l and 122 μmol/l, respectively, p = 0.03). Polymorphisms of GP VI and VWF associated with lower creatinine levels during PUUV infection. The minor C-allele of GP Ia associated with lower platelet counts (median 44 × 10⁹/l, range 20-90 × 10⁹/l vs median 64 × 10⁹/l, range 3-238 × 10⁹/l; p = 0.02).

Conclusions

Polymorphism of PAI-1, a major regulator of fibrinolysis, has an adverse impact on the outcome of kidney function in PUUV-HFRS. Platelet collagen receptor GP Ia polymorphism associates with lower platelet count.     

Plasminogen activator inhibitor-1 (PAI-1) 4G/5G polymorphism and endometriosis. Influence of PAI-1 polymorphism on PAI-1 antigen and mRNA expression

Introduction

Endometriosis is a benign gynecologic disease with a high prevalence. It is a multifactorial and polygenic entity in which the fibrinolytic system may be implicated. The objective of this study was to evaluate the plasminogen activator inhibitor-1 (PAI-1) 4G/5G polymorphism in a group of women with and without endometriosis and to analyze the influence of this polymorphism in PAI-1 expression in endometrial tissue and peritoneal fluid.

Material and methods

In 389 women (170 patients with endometriosis and 219 controls) PAI-1 4G/5G polymorphism was determined by PCR amplification using allele-specific primers. Quantitative real-time RT-PCR assay was used to quantify PAI-1 mRNA and PAI-1 antigen (ag) levels were quantified by ELISA.

Results

The genotype and allele frequencies of PAI-1 4G/5G polymorphism did not differ significantly between patients and controls. Control women with the 4G/4G genotype had higher endometrial PAI-1ag (P = 0.026) and mRNA (P = 0.014) levels than those with the 5G/5G genotype. Control carrying the 4G/4G genotype tended to have higher peritoneal fluid PAI-1ag levels than those carrying the 5G/5G genotype. Moreover, PAI-1ag levels in peritoneal fluid were higher in patients than in controls (P = 0.003).

Conclusions

The PAI-1 genotype distribution was similar in patients and controls. PAI-1 levels in endometrial tissue and peritoneal fluid seem to be associated with PAI-1 4G/5G polymorphism in controls. The increased PAI-1ag levels observed in peritoneal fluid from patients could contribute to increase the peritoneal adhesions observed in endometriosis.     

Parameters of the thrombogram are associated with serum 25-hydroxyvitamin D levels at baseline, but not affected during supplementation with vitamin D

Introduction

In vitro studies indicate an anticoagulant effect of 1,25-dihydroxyvitamin D, and sun exposure may lower the risk of thrombotic events. Accordingly, an effect on haemostatic parameters could be expected after supplementation with vitamin D.

Materials and Methods

158 obese or overweight subjects were included in a one year intervention study with supplementation with 40.000 IU vitamin D₃ per week or placebo. All subjects were given 500 mg calcium daily. Plasminogen activator inhibitor 1 (PAI-1), tissue plasminogen activator antigen (tPA Ag), and tissue factor-induced thrombin generation over time in plasma assessed by the calibrated automated thrombogram (CAT) method as a parameter of over all thrombotic activity, were measured before and at the end of the study.

Results

Mean baseline serum 25(OH)D level was 61.8 nmol/L and increased in the vitamin D group to 145.6 nmol/L at the end of the study. At baseline there was a significant decrease in the CAT variables lag time and time to peak of the thrombogram across increasing serum 25(OH)D quartiles, whereas no significant associations between serum 25(OH)D and PAI-1 or tPA Ag were found. After one year, no significant differences were found between the vitamin D and placebo groups regarding change in any of the haemostatic parameters.

Conclusions

The association between lag time and time to peak in the CAT assay and serum 25(OH)D levels could indicate a pro-thrombotic state in subjects with high serum 25(OH)D levels, whereas the lack of effect of high dose vitamin D supplementation questions the causality of this relation.     

Haemostatic system, biochemical profiles, kynurenines and the prevalence of cardiovascular disease in peritoneally dialyzed patients

Introduction

The haemostatic and biochemical abnormalities participate in the progression of cardiovascular disease (CVD) in peritoneally dialysed (PD) patients. Recently, the role of kynurenine (KYN) pathway of tryptophan (TRP) degradation in the development of CVD has been postulated.

Materials and methods

The present study was undertaken to investigate haemostatic parameters, biochemical profiles and kynurenines in PD patients both with and without CVD compared to age- and sex-matched healthy controls.

Results

The multiple biochemical abnormalities were present in PD patients, particularly in those with CVD. Tissue factor (TF), its inhibitor (TFPI), prothrombin fragment 1 + 2 (F_1 + 2)_, urokinase-type plasminogen activator (uPA), its soluble receptor (suPAR), plasmin/antiplasmin (PAP) complexes, KYN, kynurenic (KYNA) and quinolinic (QA) acids levels were significantly higher, whereas TRP was significantly lower in the PD patients than in the controls. Tissue-type plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1) were higher in the patients with CVD than in the patients without CVD and controls. PD patients with CVD had higher F_1 + 2, and they had lower suPAR and KYNA levels compared with PD patients without CVD. KYNA was positively associated with TFPI, whereas its was inversely associated with F_1 + 2 both in the whole PD group and in CVD patients. Logistic regression analysis showed that low KYNA, high glucose, low HDL-cholesterol levels and the duration of dialysis treatment were independently associated with the presence of CVD in PD patients.

Conclusions

The present study suggests a relationship between kynurenine pathway of tryptophan degradation, haemostatic and biochemical disturbances and CVD prevalence in peritoneally dialyzed patients.     

Carbon monoxide (CO)-releasing molecule-derived CO regulates tissue factor and plasminogen activator inhibitor type 1 in human endothelial cells

Introduction

Heme oxygenase-1 (HO-1) is the rate limiting enzyme that catalyzes the conversion of heme into biliverdin, free iron, and carbon monoxide (CO). The first human case of HO-1 deficiency showed abnormalities in blood coagulation and the fibrinolytic system. Thus, HO-1 or HO-1 products, such as CO, might regulate coagulation and the fibrinolytic system. This study examined whether tricarbonyldichlororuthenium (II) dimer (CORM-2), which liberates CO, modulates the expression of tissue factor (TF) and plasminogen activator inhibitor type 1 (PAI-1) in human umbilical vein endothelial cells (HUVECs), and TF expression in peripheral blood mononuclear cells (PBMCs). Additionally, we examined the mechanism by which CO exerts its effects.

Materials and Methods

HUVECs were pretreated with 50 μM CORM-2 for 3 hours, and stimulated with tumor necrosis factor-α (TNF-α, 10 ng/ml) for an additional 0-5 hours. PBMCs were pretreated with 50-100 μM CORM-2 for 1hour followed by stimulating with lipopolysaccharid (LPS, 10 ng/ml) for additional 0-9 hours. The mRNA and protein levels were determined by RT-PCR and western blotting, respectively.

Results

Pretreatment with CORM-2 significantly inhibited TNF-α-induced TF and PAI-1 up-regulation in HUVECs, and LPS-induced TF expression in PBMCs. CORM-2 inhibited TNF-α-induced activation of p38 MAPK, ERK1/2, JNK, and NF-κB signaling pathways in HUVECs.

Conclusions

CORM-2 suppresses TNF-α-induced TF and PAI-1 up-regulation, and MAPKs and NF-κB signaling pathways activation by TNF-α in HUVECs. CORM-2 suppresses LPS-induced TF up-regulation in PBMCs. Therefore, we envision that the antithrombotic activity of CORM-2 might be used as a pharmaceutical agent for the treatment of various inflammatory conditions.