Reduced in vitro clot lysis and release of more active platelet PAI-1 in polycythemia vera and essential thrombocythemia

Fibrin Clot Properties in Cancer: Impact on Cancer-Associated Thrombosis

Cancer is associated with a high risk of venous thromboembolism (VTE) and its recurrence. There is evidence that the prothrombotic fibrin clot phenotype, involving the formation of denser and stiffer clots relatively resistant to lysis, occurs in cancer patients, which is in part related to enhanced inflammation, oxidative stress, and coagulation activation, along with the release of neutrophil extracellular traps, indicating that fibrin-related mechanisms might contribute to cancer-associated thrombosis (CAT). Multiple myeloma and its therapy have been most widely explored in terms of altered fibrin characteristics, but prothrombotic fibrin clot features have also been reported in patients with active solid cancer, including lung cancer and gastrointestinal cancer. Patient-related factors such as advanced age, smoking, and comorbidities might also affect fibrin clot characteristics and the risk of CAT. Prothrombotic fibrin clot features have been shown to predict the detection of cancer in patients following VTE during follow-up. Cancer-specific therapies and anticoagulation can favorably modify the phenotype of a fibrin clot, which may alter the course of CAT. It is unclear whether the fibrin clot phenotype might help identify patients with CAT who are more likely to experience recurrent events. This narrative review summarizes the current knowledge on the role of fibrin clot structure and function in cancer patients in the context of CAT.

JAK2V617F variant allele frequency, non-driver mutations, single-nucleotide variants and polycythemia vera outcome

INTRODUCTION

Despite comparatively favourable prognosis in polycythemia vera (PV) patients (pts), the overall survival is shorter compared to the age-matched general population. The aim of the study was to evaluate the impact of chosen laboratory and genetic factors on the individual disease outcome, i.e. risk of thrombosis, myelofibrosis/blastic transformation and death.

MATERIALS AND METHODS

The study group consisted of 151 pts and 57 healthy donors (HD).

RESULTS

JAK2V617F mutation was found in 96.7% (146/151) of the studied pts. JAK2 exon 12 mutations were identified in 2 individuals. The coexistence of JAK2V617F and JAK2 exon 12 mutation was confirmed in 2 other pts. In one case, neither JAK2V617F nor JAK2 exon 12 mutation was found. The presence of ten different non-driver mutations (ASXL1, SRSF2, U2AF1, IDH2) in eight of the analyzed pts (5.3%) was confirmed. The overall frequency of thrombotic events (TE) in the studied PV group was 23.8% (36/151). In patients with TE, median platelet count was lower than in pts without TE. Thrombotic risk did not depend on JAK2 rs12343867, TERT rs2736100, OBFC1 rs9420907 SNV, however, we found a novel strong tendency towards statistical significance between the CC genotype miR-146a rs2431697 and thrombosis. The disease progression to fibrotic phase was confirmed in 9% of the pts. Fibrotic transformation in PV pts was affected mainly by JAK2V617F variant allele frequency (VAF) and the presence of coexisting non-driver variants. The high JAK2V617F VAF and elevated white blood cell (WBC) count at the time of diagnosis were associated with an increased risk of death.

CONCLUSION

Therefore, in our opinion, complex, laboratory and genetic PV pts evaluation at the time of diagnosis should be incorporated into a new prognostic scoring system to more precisely define the PV prognosis and to optimize the therapeutic decision-making process.

Altered Fibrinolysis in Hematological Malignances

Bleeding and thrombosis are well-known complications to hematological malignancies, and changes in fibrinolysis impact both these issues. In the present systematic review, we provide an overview and discussion of the current literature in regards to clinical manifestations, diagnosis, and treatment of altered fibrinolysis in patients suffering from hematological malignancies, beyond acute promyelocytic leukemia. We performed a systematic literature search employing the databases Pubmed, Embase, and Web of Science to identify original studies investigating fibrinolysis in hematological malignancies. Studies investigating fibrinolysis in acute promyelocytic leukemia or disseminated intravascular coagulation were excluded. We identified 32 studies fulfilling the inclusion criteria. A majority of the studies were published more than two decades ago, and none of the studies examined all available markers of fibrinolysis or used dynamic clot lysis assays. In acute leukemia L-asparaginase treatment induced a hypofibrinolytic state, and prior to chemotherapy there seemed to be little to no change in fibrinolysis. In studies examining fibrinolysis during chemotherapy results were ambiguous. Two studies examining multiple myeloma indicated hypofibrinolysis prior to chemotherapy, and in another plasma cell disease, amyloid light chain-amyloidosis, clear signs of hyperfibrinolysis were demonstrated. In myeloproliferative neoplasms, the studies reported signs of hypofibrinolysis, in line with the increased risk of thrombosis in this disease. Only one study regarding lymphoma was identified, which indicated no alterations in fibrinolysis. In conclusion, this systematic review demonstrated that only sparse, and mainly old, evidence exists on fibrinolysis in hematological malignancy. However, the published studies showed a tendency toward hypofibrinolysis in myeloproliferative disorders, an increased risk of hyperfibrinolysis, and bleeding in patients with AL-amyloidosis, whereas studies regarding acute leukemias were inconclusive except with regard to L-asparaginase treatment, which induced a hypofibrinolytic state.

The Association Between Modified Intracoronary Thrombus Grade and Cardiovascular Risk Factors and Initial Laboratory Findings in Patients Undergoing Primary Percutaneous Coronary Intervention

The thrombus burden has been shown to affect the immediate results of primary coronary intervention and the outcome of the patients. The aim of the present study was to determine the cardiovascular risk factors and initial laboratory findings associated with angiographic thrombotic grade based on the new reclassified grading method. A total of 394 consecutive patients presenting with a first ST-elevation myocardial infarction treated by primary coronary intervention were retrospectively evaluated between March 2014 and March 2017. Patients were divided into 2 groups of low thrombus grade (grades 1-3) and high thrombus grade (grade 4). The results showed that the patients with high thrombus grade had markedly higher white blood cell (WBC) counts, platelet counts, and initial troponin levels (P values were <0.001, 0.004, and <0.001, respectively). After logistic regression analysis, high WBC count had the strongest association with high thrombus grade [odds ratio: 3.185, 95% confidence interval: 1.349-7.520; P = 0.008]. The initial troponin level also had significant association with high thrombus grade, whereas high platelet count had a borderline statistical significance (odds ratio: 2.250, 95% confidence interval: 0.928-5.459; P = 0.073). In conclusion, the present study demonstrated that high WBC and higher levels of baseline troponin were associated with high angiographic thrombus grade in patients with ST-elevation myocardial infarction undergoing primary percutaneous coronary intervention.

Biophysical Mechanisms Mediating Fibrin Fiber Lysis

The formation and dissolution of blood clots is both a biochemical and a biomechanical process. While much of the chemistry has been worked out for both processes, the influence of biophysical properties is less well understood. This review considers the impact of several structural and mechanical parameters on lytic rates of fibrin fibers. The influences of fiber and network architecture, fiber strain, FXIIIa cross-linking, and particle transport phenomena will be assessed. The importance of the mechanical aspects of fibrinolysis is emphasized, and future research avenues are discussed.

Altered plasma fibrin clot properties in essential thrombocythemia

Patients with increased thromboembolic risk tend to form denser fibrin clots which are relatively resistant to lysis. We sought to investigate whether essential thrombocythemia (ET) is associated with altered fibrin clot properties in plasma. Ex vivo plasma fibrin clot permeability coefficient (Ks), turbidimetry and clot lysis time (CLT) were measured in 43 consecutive patients with ET (platelet count from 245 to 991 × 10(3)/µL) and 50 control subjects matched for age, sex and comorbidities. Fibrinolysis proteins and inhibitors together with platelet activation markers were determined. Reduced Ks (-38%, p < 0.0001) and prolonged CLT (+34%, p < 0.0001) were observed in ET. The differences remained significant after adjustment for fibrinogen and platelet count. ET was associated with a slightly shorter lag phase (-5%, p = 0.01) and higher maximum absorbency of the turbidimetric curve (+6%, p < 0.001). The ET patients had higher plasma P-selectin by 193% (p < 0.00001) and platelet factor 4 (PF4) by 173% (p < 0.00001), with higher P-selectin observed in 19 (44%) patients with JAK-2 gene V617F mutation. Higher t-PA (+20%, p < 0.001), 23% higher plasminogen activator inhibitor-1, PAI-1 (+23%, p < 0.01) and unaltered thrombin-activatable fibrinolysis inhibitor, plasminogen and α2-antiplasmin activity were found in the ET group. Ks inversely correlated with fibrinogen, PF4 and C-reactive protein. CLT positively correlated only with PAI-1. Patients with ET display prothrombotic plasma fibrin clot phenotype including impaired fibrinolysis, which represents a new prothrombotic mechanism in this disease.

JAK2-V617F-induced MAPK activity is regulated by PI3K and acts synergistically with PI3K on the proliferation of JAK2-V617F-positive cells

The identification of a constitutively active JAK2 mutant, namely JAK2-V617F, was a milestone in the understanding of Philadelphia chromosome-negative myeloproliferative neoplasms. The JAK2-V617F mutation confers cytokine hypersensitivity, constitutive activation of the JAK-STAT pathway, and cytokine-independent growth. In this study we investigated the mechanism of JAK2-V617F-dependent signaling with a special focus on the activation of the MAPK pathway. We observed JAK2-V617F-dependent deregulated activation of the multi-site docking protein Gab1 as indicated by constitutive, PI3K-dependent membrane localization and tyrosine phosphorylation of Gab1. Furthermore, we demonstrate that PI3K signaling regulates MAPK activation in JAK2-V617F-positve cells. This cross-regulation of the MAPK pathway by PI3K affects JAK2-V617F-specific target gene induction, erythroid colony formation, and regulates proliferation of JAK2-V617F-positive patient cells in a synergistically manner.

Prevalence of venous thromboembolism in patients with secondary polycythemia

To investigate an association between secondary polycythemia and venous thromboembolism (VTE) risk, we performed a case-control study to compare the prevalence of VTE in participants with secondary polycythemia due to chronic obstructive pulmonary disease (COPD; N = 86) to that in age- and sex-matched controls with COPD without secondary polycythemia (N = 86). Although there was a significant difference in mean hematocrit between cases and controls (53.5% vs 43.6%, respectively; P < .005), we identified no difference in the number of total or idiopathic VTE events in the 2 groups. Patients with VTE, however, had a significantly higher body mass index than patients without VTE. Our findings suggest that secondary polycythemia alone may not be a significant risk factor for VTE but that VTE risk in this population may be related to known risk factors such as obesity. The role of phlebotomy for VTE risk reduction secondary polycythemia is therefore questionable.

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)

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.

Impaired fibrinolysis as a risk factor for Budd-Chiari syndrome

In Budd-Chiari syndrome (BCS), thrombosis develops in the hepatic veins or inferior vena cava. To study the relationship between hypofibrinolysis and BCS, we measured plasma levels of fibrinolysis proteins in 101 BCS patients and 101 healthy controls and performed a plasma-based clot lysis assay. In BCS patients, plasminogen activator inhibitor 1 (PAI-1) levels were significantly higher than in controls (median, 6.3 vs 1.4 IU/mL, P < .001). Thrombin-activatable fibrinolysis inhibitor and plasmin inhibitor levels were lower than in controls (13.8 vs 16.9 μg/mL and 0.91 vs 1.02 U/L, both P < .001). Median plasma clot lysis time (CLT) was 73.9 minutes in cases and 73.0 minutes in controls (P = .329). A subgroup of cases displayed clearly elevated CLTs. A CLT above the 90th or 95th percentile of controls was associated with an increased risk of BCS, with odds ratios of 2.4 (95% confidence interval, 1.1-5.5) and 3.4 (95% confidence interval, 1.2-9.7), respectively. In controls, only PAI-1 activity was significantly associated with CLT. Analysis of single nucleotide polymorphisms of fibrinolysis proteins revealed no significant differences between cases and controls. This case-control study provides the first evidence that an impaired fibrinolytic potential, at least partially caused by elevated PAI-1 levels, is related to the presence of BCS.

[Essential thrombocythaemia as a causative agent of portal vein thrombosis--a case report]

INTRODUCTION

Thrombosis of splanchnic blood vessels is one of the most difficult complications and most frequent causes of death in patients with myeloproliferative disorders.

CASE OUTLINE

We report a 48-year-old man with recurring haemorrhage from the upper digestive tract. Doppler ultrasonography of the portal system revealed a thrombosed portal vein, with marginal flow of 10 cm/s. Peroral fiber panendoscopy of the oesophagus showed III-IV degree varices together with varices in the stomach fundus. Blood count revealed thrombocytosis (Pt. 900 x 109/l), and haematological analysis led to the diagnosis of essential thrombocythaemia. However, two years after the established diagnosis, the patient was hospitalized again for bleeding from esophageal varicosity. During haemorrhage, anticoagulant therapy was discontinued. Eight days after anticoagulant discontinuation, mesenterial thrombosis and small intestinal gangrene developed. Surgical intervention was carried out, including resection of 2.5 m of the small intestine. In spite of intensive postoperative therapy, the lethal outcome ensued.

CONCLUSION

The bleeding from oesophageal and/or gastric varicosity is often the presenting manifestation of up to that time undetected myeloproliferative disease. The following question still remains open: should anticoagulant therapy be continued in the phase of acute bleeding of these patients?

[Myeloproliferative diseases as causative agents of portal and hepatic veins thrombosis]

Thrombosis of portal and hepatic veins is one of the most severe complications and most important causes of death of patients with chronic myeloproliferative diseases. Based on results of the past studies, myeloproliferative diseases were the causes of hepatic veins thrombosis in 30% and portal vein thrombosis in 20% of patients. The study presented 4 patients with myeloproliferative diseases complicated by thrombosis of splanchnic veins, aiming at the illustration of issue complexity in diagnostics and therapy. Two patients with portal vein thrombosis and recurring hemorrhage from esophageal varicosity were described. The first case was planned for shunting, while another case sustained bleeding on what account his anticoagulant therapy was discontinued, but it caused mesenterial thrombosis resulting in lethal outcome. Another two patients had hepatic veins thrombosis. Due to frequent, life-threatening bleeding from the esophageal and gastric varices, a patient with chronic Budd-Chiari syndrome and lineal vein thrombosis underwent mesocaval shunting. An immediate postoperative period was manifested by multiple thrombosis and hemorrhages that ended in his death. A patient with the acute Budd-Chiari syndrome was administered myelosuppressants and anticoagulants on time so reperfusion was restored. In myeloproliferative diseases, thrombosis of portal and hepatic veins gives rise to excessive portal hypertension with profuse hemorrhage from the esophageal and gastric varicosity which is difficult to manage because of complex coagulation disorders.

Abdominal vein thrombosis in essential thrombocythemia: prevalence, clinical correlates, and prognostic implications

Among 460 consecutive patients with essential thrombocythemia (ET) seen at our institution, 19 cases (4%) of abdominal vein thrombosis (AVT) were documented either at (n = 9) or after (n = 10) diagnosis. Women (P = 0.03) and the young (P = 0.002) were preferentially affected. Accordingly, clinical comparisons were performed among three groups of female patients: those with AVT (group A; n = 17), a control group without AVT but closely matched to group A in terms of age and year of diagnosis (group B; n = 34), and all female patients without AVT (group C; n = 288). As expected from the consequences of AVT-associated portal hypertension and anticoagulant therapy, patients in group A experienced significantly higher rates of hemorrhage, palpable splenomegaly, and anemia. Unexpectedly, however, compared with group B, group A displayed both a higher conversion rate into myelofibrosis/acute leukemia (P = 0.0008) and a shorter median survival (116 vs. 156 months; P = 0.0012). Multivariable analysis including all female patients with ET identified AVT, along with advanced age, leukocytosis, and tobacco use, as an independent risk factor for inferior survival. Groups A, B, and C did not differ in either JAK2(V617F) mutational frequency or incidence of non-abdominal thrombosis. We conclude that AVT in ET is a marker of aggressive disease biology.

Primary and secondary thrombocytosis in childhood

This review summarizes current data on the pathomechanisms and clinical aspects of primary and secondary thrombocytosis in childhood. Primary thrombocytosis is extremely rare in childhood, mostly diagnosed at the beginning of the second decade of life. As in adults, the criteria of the Polycythemia Vera Group are appropriate to diagnose primary thrombocytosis. The pathomechansims of non-familial forms are complex and include spontaneous formation of megakaryopoietic progenitors and increased sensitivity to thrombopoietin (Tpo). Familial forms can be caused by mutations in Tpo or Tpo receptor (c-mpl) genes. These mutations result in overexpression of Tpo, sustained intracellular signalling or disturbed regulation of circulating Tpo. Treatment of primary thrombocytosis is not recommended if platelet counts are <1500/nl and bleeding or thrombosis did not occur in patient's history. In severe cases, decision on treatment should weigh potential risks of treatment options (hydroxyurea, anagrelide) against expected benefits for preventing thrombosis or haemorrhage. Secondary thrombocytosis is frequent in children, in particular in the first decade of life. Hepatic Tpo production is stimulated in acute response reaction to a variety of disorders. Thrombosis prophylaxis is not required, even at platelet counts >1000/nl, except for cases with additional prothrombotic risk factors.

Association of platelet count with residual thrombus in the myocardial infarct-related coronary artery among patients treated with fibrinolytic therapy for ST-segment elevation acute myocardial infarction

A higher platelet count is independently associated with the presence of residual thrombus in the infarct-related artery after administration of fibrinolytic therapy, even after multivariate adjustment.

Association Between Platelet Receptor Occupancy After Eptifibatide (Integrilin) Therapy and Patency, Myocardial Perfusion, and ST-Segment Resolution Among Patients With ST-Segment–Elevation Myocardial Infarction

Background— Paradoxically, fibrinolytic agents may systemically activate platelets, which in turn secrete plasminogen activator inhibitor (PAI-1), an antagonist of the fibrinolytic process in proportion to total body platelet mass. We hypothesized that improved epicardial patency, myocardial perfusion, and ST-segment resolution would be associated with higher levels of platelet receptor occupancy (RO) by a glycoprotein IIb/IIIa antagonist in ST-elevation MI (STEMI).

Methods and Results— Patients were drawn from the low-dose tenecteplase plus eptifibatide arm of the INTEGRITI study. Angiographic and platelet RO data were analyzed at 2 independent core laboratories. To take into account the absolute platelet count and receptors available for cross-linking, absolute platelet count was multiplied by percent of available receptors to obtain the index of the absolute number of receptors available (IANRA). Percent RO was higher among patients with a patent artery (TIMI flow grade 2/3; 78.2±9.2, n=63 versus 63.9±29.7, n=7; P =0.005), those with TIMI myocardial perfusion grade 2/3 (79.6±9.5, n=40 versus 73.0±16.2, n=30; P =0.036), and those with complete (≥70%) ST-segment resolution at 60 minutes (81.3±8.3%, n=27 versus 73.1±17.4%, n=24; P =0.034). The absolute number of glycoprotein IIb/IIIa receptors available for cross-linking was reduced (ie, the IANRA was lower) among patients with a patent artery ( P =0.0015), patients with TIMI myocardial perfusion grade 2/3 ( P =0.026), and patients with ≥70% ST-segment resolution ( P =0.029).

Conclusions— This study links restoration of epicardial flow, normal myocardial perfusion, and complete ST-segment resolution with higher levels of platelet glycoprotein IIb/IIIa receptor occupancy after therapy with eptifibatide administered with tenecteplase.

Polycythemia vera: a comprehensive review and clinical recommendations

More than a century has elapsed since the appearance of the modern descriptions of polycythemia vera (PV). During this time, much has been learned regarding disease pathogenesis and PV-associated molecular aberrations. New information has allowed amendments to traditional diagnostic criteria. Phlebotomy remains the cornerstone treatment of PV, whereas myelosuppressive agents may augment the benefit of using phlebotomy for thrombosis prevention in high-risk patients. Excessive aspirin use is contraindicated in PV, although the use of lower-dose aspirin has been shown to be safe and effective in alleviating microvascular symptoms including erythromelalgia and headaches. Recent studies have shown the utility of selective serotonin receptor antagonists for treating PV-associated pruritus. Nevertheless, many questions remain unanswered. What is the specific genetic mutation or altered molecular pathway that is causally related to the disease? In the absence of a specific molecular marker, how is a working diagnosis of PV made? What evidence supports current practice in the management of PV? This article summarizes both old and new information on PV; proposes a modern diagnostic algorithm to formulate a working diagnosis; and provides recommendations for patient management, relying whenever possible on an evidence-based approach.

Polycythemia vera--a case report and discussion on pathogenic mechanisms of increased thrombosis

Polycythemia vera is a myeloproliferative disorder characterized by increased red cell mass and frequently complicated by venous and arterial thrombosis. The mechanism underlying the increased incidence of thrombotic events remains illusive. Presented in this report are a case of a 77-year-old man diagnosed with polycythemia vera and a review of the current literature on the mechanisms underlying the increased incidence of thrombotic events in polycythemia vera.

Acquired thrombophilic syndromes

As the biochemical mechanisms of hypercoagulable states are revealed, the syndromes of venous thromboembolism have been increasingly associated with specific aberrations. Most of these changes involve an increase in procoagulant potential, for example, by activation of the coagulation cascade, or by a defect or decrease in natural inhibitors of clotting. Similar abnormalities of the fibrinolytic pathways may contribute, as can loss of inhibitory mechanisms of endothelial cells, as well as changes in vascular anatomy and rheologic patterns of blood flow. All of these factors can directly influence thrombus formation and/or the physiologic response to the thrombus.(1)

Clinical implications of elevated PAI-1 revisited: multiple arterial thrombosis in a patient with essential thrombocythemia and elevated plasminogen activator inhibitor-1 (PAI-1) levels: a case report and review of the literature

Plasminogen activator inhibitor (PAI-1), a member of the serine protein family, is the most active in vivo inhibitor of fibrinolysis induced by plasminogen, tissue plasminogen activator (tPA), and urokinase type plasminogen activator (uPA). While the association between elevated PAI-1 and thrombogenesis has been well studied for several disease processes, including coronary disease, postoperative deep vein thrombosis (DVT), myocardial infarction, malignancy, and diabetes, few studies have concentrated on the correlation between elevated PAI-1 levels and thrombogenesis in patients with myeloproliferative disorders. Essential thrombocythemia (ET), a chronic myeloproliferative disorder, characterized by the overproduction of poorly functioning platelets, is associated with both thrombotic and hemorrhagic life-threatening complications. Although the events resulting in thrombogenesis in such patients may be multifactorial in nature, an association between elevated PAI-1 levels and thrombus formation has been proposed. Herein we present a patient diagnosed with ET complicated by multiple episodes of arterial thrombosis. Elevations in PAI-1 levels were documented repeatedly. The role of elevated PAI-1 when associated with other disease processes is also discussed.