Calcium Prevents Enhanced Degradation of Factor VIII in the Condition of Motion.

Background: Hemophilia A and B induce recurrent bleeding episodes, mainly in skeletal muscles and joints that are in intermittent motion. We have previously demonstrated that intermittent motion contributes to increased degradation of factors VIII and IX. Objectives: Given that calcium ions are known to enhance factor VIII-von Willebrand factor (vWF) interaction, the present study has investigated the role of these ions on factors VIII and IX in the condition of motion. Methods: The effects of calcium ions were assessed using purified proteins via Western blot, factor VIII activity, immunocytochemistry, and in Institute of Cancer Research (ICR) mice with no specific genetic background. Results: Calcium was found to prevent degradation of plasma-derived factor VIII but not that of factor IX, during intermittent motion. Calcium levels in the microcirculation of mouse striated muscles were elevated following movement, enabling prevention of factor VIII degradation in normal physiology. Calcium supplementation in drinking water increased factor VIII levels in blood and striated muscles of ICR mice during movement. Conclusions: calcium ions decrease factor VIII degradation in the condition of motion. Further research on the impact of calcium salt oral supplementation on hemophilia patients is warranted.

Tissue factor-heparanase complex: intracellular nonhemostatic effects.

Background: Heparanase, known to be involved in angiogenesis, cancer progression, and inflammation, was shown to form a complex with tissue factor (TF) via its procoagulant domain and to enhance the hemostatic system. Objectives: To reveal a potential role of heparanase procoagulant domain in nonhemostatic effects. Methods: Effects of peptides 16 and 16AC derived from the heparanase procoagulant domain, discovered by our group, were studied using the XTT proliferation assay, western blot analysis, and immunostaining in vitro and a mouse wound-healing model. Results: Procoagulant peptides induced increased proliferation, release of heparanase, and upregulation of heparanase, TF, tissue factor pathway inhibitor (TFPI), and TFPI-2 in U87, T47D, and MCF-7 tumor cell lines and in endothelial cells. These results were reversed by a peptide derived from TFPI-2 that inhibited the heparanse procoagulant domain-TF complex. Thrombin had a similar effect on tumor cell proliferation and heparanase release, although the impact of thrombin on cell proliferation was mediated by the heparanase procoagulant domain. A mouse model of full-thickness skin incision exhibited higher levels of heparanase, TF, TFPI, and TFPI-2 in the healing skin, mainly in the blood vessel wall and lumen in animals injected with the procoagulant peptides compared to controls. The cells transfected to overexpress full-length TF or TF devoid of the cytoplasmic domain demonstrated that the procoagulant domain conveyed intracellular signaling via TF. Conclusion: Heparanase procoagulant domain induces nonhemostatic effects via TF. The finding that TF serves as a receptor to heparanase supports the close direct relation between the hemostatic system and cancer progression.

Effect of Heparanase and Heparan Sulfate Chains in Hemostasis.

Heparanase, the only mammalian enzyme known to degrade heparan sulfate chains, affects the hemostatic system through several mechanisms. Along with the degrading effect, heparanase engenders release of syndecan-1 from the cell surface and directly enhances the activity of the blood coagulation initiator, tissue factor, in the coagulation system. Upregulation of tissue factor and release of tissue factor pathway inhibitor from the cell surface contribute to the prothrombotic effect. Tissue factor pathway inhibitor and the strongest physiological anticoagulant antithrombin are attached to the endothelial cell surface by heparan sulfate. Hence, degradation of heparan sulfate induces further release of these two natural anticoagulants from endothelial cells. Elevated heparanase procoagulant activity and heparan sulfate chain levels in plasma, demonstrated in cancer, pregnancy, oral contraceptive use, and aging, could suggest a potential mechanism for increased risk of thrombosis in these clinical settings. In contrast to the blood circulation, accumulation of heparan sulfate chains in transudate and exudate pleural effusions induces a local anticoagulant milieu. The anticoagulant effect of heparan sulfate chains in other closed spaces such as peritoneal or subdural cavities should be further investigated.

Progestin type affects the increase of heparanase level and procoagulant activity mediated by the estrogen receptor.

STUDY QUESTION: Does progestin have an effect on heparanase level and procoagulant activity? SUMMARY ANSWER: Progestin increases the heparanase level and procoagulant activity via the estrogen receptor and the magnitude of the effect depends on the progestin type. WHAT IS KNOWN ALREADY: Users of combined oral contraceptives (COCs) containing third- and fourth-generation progestins have a higher risk of venous thrombosis compared to those employing second-generation progestins. Heparanase protein is capable of degrading heparan sulfate (HS) chains and enhancing activation of the coagulation system. We have previously demonstrated that estrogen enhances the expression and procoagulant activity of heparanase. STUDY DESIGN, SIZE, DURATION: Estrogen and progestin receptor positive breast carcinoma cell lines: EMT6, T47D and MCF-7 were compared to the MDA-231 breast carcinoma cell line devoid of these receptors. This observational study incorporated 45 users of third-generation COCs progestins, 21 users of fourth-generation COCs progestins and 28 individuals not using hormonal therapy and not pregnant per history. PARTICIPANTS/MATERIALS, SETTING, METHODS: Second-generation progestin-levonorgestrel, third-generation progestin-desogastrel (DSG), an estrogen receptor antagonist-ICI 182.780 and a progestin receptor antagonist-mifepristone, were added to cell lines. Heparanase level and procoagulant activity, HS levels, tissue factor (TF) activity and factor Xa levels were evaluated in the plasma of the study group. MAIN RESULTS AND THE ROLE OF CHANCE: Levonorgestrel and DSG increased heparanase levels in the cells and medium. The effect of DSG was more prominent and additive to that of estrogen. The effect was inhibited by ICI 182.780. In the plasma of COC users, heparanase procoagulant activity, HS levels, TF activity and factor Xa levels were significantly higher compared to controls. In COC pills containing the same dose of estrogen, the procoagulant effect of drospirenone was significantly stronger than that of DSG and gestodene. LIMITATIONS, REASONS FOR CAUTION: The limitations of the study include a small number of participants in each study group, although the results are statistically significant and evaluated by several different coagulation parameters. WIDER IMPLICATIONS OF THE FINDINGS: The study demonstrates a new mechanism through which progestin affects coagulation system activation and shows that this effect is progestin type-dependent. Development of a progestin derivative with an attenuated effect on heparanase procoagulant activity may reduce thrombotic risk. STUDY FUNDING/COMPETING INTEREST(S): No external funding was sought for this study. Y.N. is named in a European patent application No. IL201200027 filed on 18 January 2012. Other authors have no conflict of interest to declare. TRIAL REGISTRATION NUMBER: N/A.

Heparanase Level and Procoagulant Activity Are Increased in Thalassemia and Attenuated by Janus Kinase 2 Inhibition.

Patients with thalassemia exhibit an increased risk of thrombotic events that is augmented after splenectomy. Heparanase protein enhances cancer progression, angiogenesis, and inflammation; it also activates the coagulation system through direct interaction with tissue factor (TF). Additionally, erythropoietin, which is elevated in anemic patients, up-regulates heparanase expression via the Janus kinase 2 (JAK-2) pathway. This study aimed was to explore the heparanase profile in thalassemia. Coagulation factors were analyzed via immunostaining, enzyme-linked immunosorbent assay, and heparanase procoagulant activity assay. In spleen specimens of thalassemia major patients, a higher level of heparanase staining was observed compared with control spleens resected after trauma (P < 0.001). Higher heparanase levels, heparanase and TF procoagulant activity, and erythropoietin levels were found in the plasma of 67 thalassemia major patients compared with 29 control subjects. No difference was found in pediatric patients (23 of 67) compared with adults or splenectomized versus nonsplenectomized patients. Higher levels of heparanase, TF, TF pathway inhibitor, and TF pathway inhibitor-2 were observed in liver, spleen, heart, and kidney tissues of thalassemia intermedia mice (Hbbth3/+). These protein levels significantly reduced when mice were treated with the JAK-2 inhibitor ruxolitinib (P < 0.0001). In summary, heparanase levels are elevated in thalassemia, which may contribute to thrombotic phenomena in these patients. Inhibition of heparanase or the JAK-2 pathway may reduce thrombotic risk in thalassemia.

Circulating heparan sulfate chains and body weight contribute to anti-Xa levels in cancer patients using the prophylactic dose of enoxaparin.

Hospitalized cancer patients are at increased risk of thrombosis and prophylaxis with heparin is recommended. Heparanase is a protein capable of degrading heparan sulfate (HS) chains. The first objective of the study was to examine the effects of weight on anti-Xa levels in cancer patients treated with a fixed dose of enoxaparin as thromboprophylaxis. The second aim was to assess a potential correlation between plasma pre-treatment coagulation parameters and anti-Xa levels in an assumption that heparanase degradation activity towards heparins and HS chains could affect anti-Xa levels. Two blood samples (prior to and 3 h after drug injection) of 76 cancer patients with an indication for prophylaxis with enoxaparin (40 mg) were evaluated for coagulation markers. Sub-prophylactic levels of anti-Xa (< 0.2 U/ml) were found in 16/76 (21%) patients; in 13/76 (13%) patients the values were supra-prophylactic (> 0.5 U/ml). In the subgroup of patients weighing > 80 kg, 7/14 (50%) individuals had a sub-prophylactic level. Overall, anti-Xa levels appeared to correlate with patient's weight (r = - 0.48, p < 0.0001), pre-treatment partial thromboplastin time (PTT), D-dimer, HS, heparanase levels and procoagulant activity. We concluded that plasma anti-Xa levels correlated with patient's weight. A substantial portion of cancer patients receiving enoxaparin prophylaxis was undertreated. For patients > 80 kg, a weight-adjusted prophylactic dose of enoxaparin could be considered. Elevated enoxaparin anti-Xa levels correlated with pre-treatment parameters of coagulation system activation. High pre-treatment HS and elevated plasma anti-Xa levels may potentially serve as biomarkers for the identification of patients at increased thrombosis risk.

Heparanase in the Coagulation System.

The hemostatic cascade is initiated by the transmembrane coagulation protein - tissue factor (TF) and eventuates in fibrin formation. Heparanase protein was demonstrated to directly enhance TF activity resulting in increased activation of the coagulation system. In addition, heparanase was found to increase hemostatic system activation via two other mechanisms: up-regulating TF expression in endothelial cells and releasing the protein tissue factor pathway inhibitor (TFPI) from the cell surface. Peptides derived from TFPI-2, a protein similar to TFPI, were shown to inhibit the TF/heparanase complex as well as attenuate sepsis and tumor growth. Increased heparanase procoagulant activity was observed in several clinical settings, including women using oral contraceptives, women at delivery, patients following orthopedic surgery and patients with diabetic foot, shift work female nurses, patients with lung cancer, retinal vein thrombosis and prosthetic heart valve thrombosis. Remarkably, the heparanase profile was significantly different across the tested groups. Inhibition of TF / heparanase interaction may represent a new target for attenuating coagulation, cancer and inflammation.

Heparan sulfate chains contribute to the anticoagulant milieu in malignant pleural effusion.

BACKGROUND: While malignant pleural effusion (MPE) is a common and significant cause of morbidity in patients with cancer, current treatment options are limited. Human heparanase, involved in angiogenesis and metastasis, cleaves heparan sulfate (HS) side chains on the cell surface. AIMS: To explore the coagulation milieu in MPE and infectious pleural effusion (IPE) focusing on the involvement of heparanase. METHODS: Samples of 30 patients with MPE and 44 patients with IPE were evaluated in comparison to those of 33 patients with transudate pleural effusions, using heparanase ELISA, heparanase procoagulant activity assay, thrombin and factor Xa chromogenic assays and thromboelastography. A cell proliferation assay was performed. EMT-6 breast cancer cells were injected to the pleural cavity of mice. A peptide inhibiting heparanase activity was administered subcutaneously. RESULTS: Levels of heparanase, factor Xa and thrombin were significantly higher in exudate than transudate. Thromboelastography detected almost no thrombus formation in the whole blood, mainly on MPE addition. This effect was completely reversed by bacterial heparinase. Direct measurement revealed high levels of HS chains in pleural effusions. Higher proliferation was observed in tumour cell lines incubated with exudate than with transudate and it was reduced when bacterial heparinase was added. The tumour size in the pleural cavity of mice treated with the heparanase inhibitor were significantly smaller compared with control (p=0.005). CONCLUSIONS: HS chains released by heparanase form an anticoagulant milieu in MPE, preventing local thrombosis and enabling tumour cell proliferation. Inhibition of heparanase might provide a therapeutic option for patients with recurrent MPE.

Decreasing Tumor Growth and Angiogenesis by Inhibition of Coagulation.

Data regarding the effect of coagulation proteins on enhancing angiogenesis and tumor growth are ample. Thus, inhibition of the coagulation system in an attempt to reduce tumor growth and metastasis seems appealing. However, such molecules as direct oral anticoagulants, warfarin and heparins, may impose a bleeding tendency, limiting the treatment dose that can be used. The heparanase protein, as a cofactor for tissue factor (TF) activity, enhances activation of the coagulation system and in addition has several nonhemostatic effects increasing tumor growth. The molecules currently investigated in the field of cancer and coagulation are heparin mimetics and inhibitors of heparanase derived from TF pathway inhibitor 2. Both groups of molecules are inhibitors of heparanase and in addition pose a low bleeding tendency. Hence, interfering in heparanase activity seems to be a promising target for development of antitumor drugs.

Heparanase Level in the Microcirculation as a Possible Modulator of the Metastatic Process.

Metastasis most commonly occurs in the liver, lung, bone, and brain, implying its preference for specific organs. We hypothesized that organ microcirculation coagulation environment predisposes to tumor cell retention. Coagulation factors were analyzed using immunostaining, enzyme-linked immunosorbent assay, and heparanase procoagulant activity assay. In normal mice, expression levels of heparanase, tissue factor (TF), TF pathway inhibitor (TFPI), and TFPI-2 were low in the microcirculation of the liver, lung, brain cortex, and bone, and high in the microcirculation of the subcutis, skeletal muscle, brain subcortex, and bone marrow. C57BL/6 mice injected s.c. with B16 (F10) melanoma cells demonstrated lower levels of heparanase, TF, TFPI, and TFPI-2 in metastasis blood vessels compared to those in the primary tumor. In these mice with metastasis, liver and lung microcirculation turned to express high levels of coagulation proteins. Additionally, although mice with heparanase overexpression developed a larger primary tumor, they did not demonstrate a tendency for metastasis, as opposed to controls (P < 0.0001). Human umbilical vein endothelial cells, incubated with the B16 melanoma cell medium for 2 hours, expressed decreased levels of heparanase, TF, TFPI, and TFPI-2, and the effect was reversed by a peptide-inhibiting heparanase/TF complex interaction (P < 0.001). In summary, metastasis has a predilection to organs with low levels of heparanase, TF, TFPI, and TFPI-2 in the microcirculation, which enables tumor cell retention. Heparanase has a role in regulating the microcirculation milieu.

[COAGULATION - A PHYSIOLOGICAL SYSTEM INTERFACING ALL OTHER BODY SYSTEMS].

INTRODUCTION: The coagulation system is a rapidly advancing area of clinical and basic research. Among the critical clinical issues to be urgently addressed are those related to the application of new direct oral anticoagulants in real life. Extensive research in the challenging field of thrombosis and bleeding is ongoing and has already resulted in new pharmacological modalities such as siRNA. The well-established close association between coagulation and cancer provides a strong incentive for developing drugs capable of interfering with the coagulation system and attenuating tumor growth. The multifaceted research field in coagulation requires dedicating specialized personnel in the hospitals along with bridging staff mediating between the hospital and the outpatient clinics to ensure proper patient management.

Cancer and Thrombosis-New Insights.

Cancer patients have a pro-thrombotic state attributed to the ability of cancer cells to activate the coagulation system and interact with hemostatic cells, thus tilting the balance between pro- and anticoagulants. Mechanisms underlying the coagulation system activation involve tumor cells, endothelial cells, platelets, and white blood cells. Anti-cancer therapies, including anti-angiogenic drugs, significantly increase the risk of thrombosis during treatment. Along with the role of coagulation proteins in the hemostatic system, these proteins also serve as growth factors to the tumor. Heparanase is a pro-angiogenic and pro-metastatic protein. Our previous studies have demonstrated that it enhances tissue factor (TF) activity and is present at high levels in tumor cells and patients' blood. Strategies to attenuate heparanase effects by heparin mimetics or peptides interrupting the TF-heparanase interaction are good candidates to attenuate tumor growth and thrombotic manifestations.

The endothelial tumor suppressor p53 is essential for venous thrombus formation in aged mice.

Venous thromboembolism (VTE) is a leading cause of morbidity and mortality in elderly people. Increased expression of tumor suppressor protein 53 (p53) has been implicated in vascular senescence. Here, we examined the importance of endothelial p53 for venous thrombosis and whether endothelial senescence and p53 overexpression are involved in the exponential increase of VTE with age. Mice with conditional, endothelial-specific deletion of p53 (End.p53-KO) and their wild-type littermates (End.p53-WT) underwent subtotal inferior vena cava (IVC) ligation to induce venous thrombosis. IVC ligation in aged (12-month-old) End.p53-WT mice resulted in higher rates of thrombus formation and greater mean thrombus size vs adult (12-week-old) End.p53-WT mice, whereas aged End.p53-KO mice were protected from vein thrombosis. Analysis of primary endothelial cells from aged mice or human vein endothelial cells after induction of replicative senescence revealed significantly increased early growth response gene-1 (Egr1) and heparanase expression, and plasma factor Xa levels were elevated in aged End.p53-WT, but not in End.p53-KO mice. Increased endothelial Egr1 and heparanase expression also was observed after doxorubicin-induced p53 overexpression, whereas p53 inhibition using pifithrin-α reduced tissue factor (TF) expression. Importantly, inhibition of heparanase activity using TF pathway inhibitor-2 (TFPI2) peptides prevented the enhanced venous thrombus formation in aged mice and restored it to the thrombotic phenotype of adult mice. Our findings suggest that p53 accumulation and heparanase overexpression in senescent endothelial cells are critically involved in mediating the increased risk of venous thrombosis with age and that heparanase antagonization may be explored as strategy to ameliorate the prothrombotic endothelial phenotype with age.

Novel strategies of coagulation inhibition for reducing tumor growth and angiogenesis.

Activated proteins of the coagulation system are known to enhance angiogenesis and tumor growth. Notably, the main coagulation proteins involved are those of the extrinsic and common pathways. Strategies to attenuate tumor progression by decreasing activation of the coagulation system may be compromised by an increased risk of bleeding. Currently, studies using derivatives of heparins devoid of or with low anticoagulant activity are being conducted. Heparanase protein was demonstrated to enhance tissue factor activity. In-house developed peptides, deriving from tissue factor pathway inhibitor 2 (TFPI-2) were shown to inhibit heparanase procoagulant activity by interrupting the interaction between TF and heparanase. These peptides appeared to have a non-hemostatic anti-angiogenic effect. In a mouse model, the peptides caused a significant reduction in tumor growth and relapse, without predisposing to bleeding. Hence, the effects of these inhibitory peptides in cancer patients may deserve further investigation in clinical research studies.

Heparanase level and procoagulant activity are reduced in severe sepsis.

BACKGROUND: During severe sepsis, levels and activity of all coagulation proteins are reduced. Heparanase is implicated in angiogenesis and tumor progression. We previously demonstrated that heparanase also affected the hemostatic system. It forms a complex and increases the activity of the blood coagulation initiator tissue factor. AIM: To evaluate heparanase levels and procoagulant activity as predictors of sepsis severity. MATERIALS AND METHODS: Twenty-one patients with non-trauma, non-surgical sepsis admitted to the intensive care unit and 35 controls were recruited. Plasma samples were drawn from the study participants on days 1 and 7 following admission. RESULTS: Heparanase levels and procoagulant activity on day 1 were significantly reduced in patients compared to controls (P < .0001, P < .0001, respectively). Day 1 heparanase procoagulant activity ≥350 ng/mL yielded a negative predictive value for severe sepsis of 89%. Additionally, heparanase procoagulant activity on day 7 correlated with the change in the APACHE score between days 1 and 7 (r = .66, P = .007). CONCLUSIONS: Heparanase procoagulant activity decreases during sepsis and returns to normal levels as soon as the patient recovers. Hence, it can be potentially used to predict the risk of severe sepsis. These findings need to be further explored in large-scale studies.

Thrombin is a selective inducer of heparanase release from platelets and granulocytes via protease-activated receptor-1.

Heparanase, known to be involved in angiogenesis and metastasis, was shown to form a complex with tissue factor (TF) and to enhance the generation of factor Xa. Platelets and granulocytes contain abundant amounts of heparanase that may enhance the coagulation system upon discharge. It was the aim of this study to identify the inducer and pathway of heparanase release from these cells. Platelets and granulocytes were purified from pooled normal plasma and were incubated with ATP, ADP, epinephrine, collagen, ristocetin, arachidonic acid, serotonin, LPS and thrombin. Heparanase levels were assessed by ELISA, heparanase procoagulant activity assay and western blot analysis. The effects of selective protease-activated receptor (PAR)-1 and 2 inhibitors and PAR-1 and 4 activators were studied. An in-house synthesised inhibitory peptide to heparanase was used to evaluate platelet heparanase involvement in activation of the coagulation system. Heparanase was released from platelets only by thrombin induction while other inducers exerted no such effect. The heparanase level in a platelet was found to be 40 % higher than in a granulocyte. Heparanase released from platelets or granulocytes increased factor Xa generation by three-fold. PAR-1 activation via ERK intracellular pathway was found to induce heparanase release. In conclusion, heparanase is selectively released from platelets and granulocytes by thrombin interacting with PAR-1. Heparanase derived from platelets and granulocytes is involved in activation of the extrinsic coagulation pathway. The present study implies on a potential anticoagulant effect, in addition to anti-platelet effect, of the new clinically studied PAR-1 inhibitors.

Peptides inhibiting heparanase procoagulant activity significantly reduce tumour growth and vascularisation in a mouse model.

Heparanase is implicated in angiogenesis and tumour progression. We previously demonstrated that heparanase might also affect the haemostatic system in a non-enzymatic manner. It forms a complex and enhances the activity of the blood coagulation initiator tissue factor (TF). Peptides that we generated from TF pathway inhibitor (TFPI)-2, which inhibit heparanase procoagulant activity, were recently demonstrated to attenuate inflammation in a sepsis mouse model. The present study was designated to explore peptides effects on tumour growth and vascularisation. Cell lines of mouse melanoma (B16), mouse breast cancer (EMT-6), and human breast cancer (MDA-231) were injected subcutaneously to mice. Inhibitory peptides 5, 6 and 7 were injected subcutaneously in the area opposite to the tumour side. In the three tumour cell lines, peptides 5, 6 and 7 inhibited tumour growth and vascularisation in a dose-dependent manner, reaching a 2/3 reduction compared to control tumours (p<0.001). Additionally, a survival advantage (p<0.05) and reduced plasma thrombin-antithrombin complex (p<0.05) were observed in the treatment groups. Peptides delayed tumour relapse by six days and inhibited relapsed tumour size (p<0.001). In vitro, peptides did not inhibit tumour cell proliferation, migration or heparanase degradation of heparan sulfate chains, but significantly decreased tube formation. In conclusion, peptides inhibiting heparanase procoagulant activity significantly reduced tumour growth, vascularisation, and relapse. The procoagulant domain in heparanase protein may play a role in tumour growth, suggesting a new mechanism of coagulation system involvement in cancer.

Haematological malignancies in pregnancy: An overview with an emphasis on thrombotic risks.

With increase of maternal age, the incidence of haematological malignancies during pregnancy is rising and posing diagnostic and treatment challenges. Lymphoma is the fourth most common malignancy diagnosed in pregnancy; Hodgkin lymphoma is more frequent in pregnant women than non-Hodgkin lymphoma (NHL). The proportion of highly aggressive lymphomas in pregnant women is significantly higher than in non-pregnant women of reproductive age. Reproductive organ involvement is observed in almost half of pregnant women with NHL. The association of acute leukaemia and pregnancy is infrequent and it is assumed that pregnancy does not accelerate the disease course. Both cancer and pregnancy induce a procoagulant state which can lead to maternal venous thromboembolism (VTE) and placental occlusion. Pregnancy in woman with myeloproliferative neoplasms (MPN) promotes thrombotic environment, associating with an augmented risk of placental thrombosis, intrauterine growth retardation or loss and maternal thrombotic events.Haematological malignancies during pregnancy often require urgent diagnosis and management and are associated with potential adverse fetal outcomes. Most chemotherapeutic agents are teratogenic and should be avoided during the first trimester. Their use during the second and third trimesters may cause intrauterine growth restriction, premature birth and intrauterine fetal death. All chemotherapeutic drugs should be administered only after a detailed discussion with the patient and with close fetal monitoring. Chemotherapy and biological agents might also augment thrombotic risk. Guidelines for VTE prophylaxis in pregnant women with hematologic malignancies, apart from MPN, are currently unavailable, and therefore, clinical judgment should be made in each case.

Dehydration as a Possible Cause of Monthly Variation in the Incidence of Venous Thromboembolism.

BACKGROUND: Monthly or seasonal changes in the incidence of venous thromboembolism (VTE) were previously reported; however, the mechanism of such variability is not completely understood. METHODS: In the present retrospective single-center analysis, consecutive patients with proximal deep vein thrombosis and/or pulmonary embolism (PE) diagnosed between January 2009 and December 2013 were evaluated. RESULTS: The study population included 1496 patients, 48% men, mean age 63 ± 18 years. Most (82%) cases with VTE were provoked and 39% of patients had active cancer. Four months of peak incidence (3, 7, 10 and 11) were compared with 4 months of the lowest incidence (4, 5, 6, and 12), showing a significant difference in VTE numbers (597 vs 405 cases/year, P = 0.001). In all subgroup analyses, including gender, provoked or unprovoked event and presence or absence of cancer, significant differences between the months of peak and lowest incidence remained. Blood urea nitrogen (BUN)-creatinine ratio was significantly higher in all cases in the peak incidence group compared to the lowest incidence group (24 ± 1.5 vs 21 ± 1.6, P = 0.03). In patients with unprovoked VTE (n = 269), levels of BUN and hematocrit were significantly increased in the peak incidence group compared to lowest incidence group (19.5 ± 0.8 mg/dL vs 16 ± 1.1 mg/dL, P = 0.03; 39.2 ± 0.3% vs 37.4 ± 0.5%, P = 0.01, respectively). CONCLUSIONS: The current study demonstrates that occurrence of VTE exhibits monthly variation also existing in patients with provoked events and even in those with cancer. Dehydration is suggested as a potential explanation to the month-related variation in incidence of VTE.

Heparanase procoagulant activity in cancer progression.

Heparanase is an endo-ß-D-glucuronidase that is capable of cleaving heparan sulfate side chains of heparan sulfate proteoglycans on cell surfaces and the extracellular matrix. This activity is strongly implicated in tumor metastasis and angiogenesis. We have earlier demonstrated that apart of its well characterized enzymatic activity, heparanase may also affect the hemostatic system in a non-enzymatic manner. We showed that heparanase up-regulated the expression of the blood coagulation initiator-tissue factor (TF) and interacted with the tissue factor pathway inhibitor (TFPI) on the cell surface membrane of endothelial and tumor cells, leading to dissociation of TFPI and resulting in increased cell surface coagulation activity. Moreover, we demonstrated that heparanase directly enhanced TF activity, which led to increased factor Xa production and subsequent activation of the coagulation system. In patients with cancer, increased heparanase procoagulant activity appeared to be a potential predictor of survival. We have also shown that JAK-2 is involved in heparanase up-regulation via the erythropoietin receptor, a finding that may point to a new mechanism of thrombosis in JAK-2 positive patents with essential thrombocytosis. Recently, we found that the solvent accessible surface of TFPI-2 first Kunitz domain had a role in TF/heparanase complex inhibition. Peptides derived from TFPI-2 inhibitory site were shown to reduce coagulation activation induced by heparanase and to attenuate sepsis severity and tumor growth in a mouse model, without predisposing to significant bleeding tendency. These data imply that inhibition of heparanase procoagulant domain is potentially a good target for sepsis and cancer therapy.