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.

Heparanase procoagulant activity as a predictor of wound necrosis following diabetic foot amputation.

BACKGROUND: Trans-metatarsal operation to diabetic foot necrosis is a common procedure although only half of the patients do not need a second amputation due to surgery wound ischemia. No current tools are available for early prediction of surgery success and the clinical decision for a second operation may take weeks. Heparanase protein is involved in inflammation, angiogenesis and coagulation activation. The aim of the study was to evaluate heparanase level and procoagulant activity as an early predictor for success or failure of diabetic foot trans-metatarsal surgery. METHODS: The study group included 40 patients with diabetic foot necrosis requiring trans-metatarsal surgical intervention. Eighteen patients designated as necrotic group, developed post-surgery necrosis at the surgery wound within the first month, requiring a second more proximal amputation. Skin biopsies from the proximal surgery edge were stained for heparanase, tissue factor (TF), TF pathway inhibitor (TFPI) and by hematoxylin and eosin. Plasma samples were drawn pre-surgery and at 1h, 1week and 1month post-surgery. Samples were tested for heparanase levels by ELISA and TF+heparanase activity, TF activity and heparanase procoagulant activity. RESULTS: Skin biopsy staining did not predict subsequent necrosis. In the non-necrotic group a significant rise in TF+heparanase activity, heparanase activity and heparanase levels were observed 1h and 1week post-surgery. The most significant increase was in heparanase procoagulant activity at the time point of 1h post-surgery (P<0.0001). Pre-surgery TF activity was significantly lower in the non-necrotic group compared to the necrotic group (P<0.05). CONCLUSIONS: Measuring heparanase procoagulant activity pre-surgery and 1h post-surgery could potentially serve as an early tool to predict the procedure success. The present results broaden our understanding regarding early involvement of heparanase in the wound healing process.

JAK-2 V617F mutation increases heparanase procoagulant activity.

Patients with polycythaemia vera (PV), essential thrombocythaemia (ET) and primary myelofibrosis (PMF) are at increased risk of arterial and venous thrombosis. In patients with ET a positive correlation was observed between JAK-2 V617F mutation, that facilitates erythropoietin receptor signalling, and thrombotic events, although the mechanism involved is not clear. We previously demonstrated that heparanase protein forms a complex and enhances the activity of the blood coagulation initiator tissue factor (TF) which leads to increased factor Xa production and subsequent activation of the coagulation system. The present study was aimed to evaluate heparanase procoagulant activity in myeloproliferative neoplasms. Forty bone marrow biopsies of patients with ET, PV, PMF and chronic myelogenous leukaemia (CML) were immunostained to heparanase, TF and TF pathway inhibitor (TFPI). Erythropoietin receptor positive cell lines U87 human glioma and MCF-7 human breast carcinoma were studied. Heparanase and TFPI staining were more prominent in ET, PV and PMF compared to CML. The strongest staining was in JAK-2 positive ET biopsies. Heparanase level and procoagulant activity were higher in U87 cells transfected to over express JAK-2 V617F mutation compared to control and the effect was reversed using JAK-2 inhibitors (Ruxolitinib, VZ3) and hydroxyurea, although the latter drug did not inhibit JAK-2 phosphorylation. Erythropoietin increased while JAK-2 inhibitors decreased the heparanase level and procoagulant activity in U87 and MCF-7 parental cells. In conclusion, JAK-2 is involved in heparanase up-regulation via the erythropoietin receptor. The present findings may potentially point to a new mechanism of thrombosis in JAK-2 positive ET patients.

Nephroprotective effect of heparanase in experimental nephrotic syndrome.

BACKGROUND: Heparanase, an endoglycosidase that cleaves heparan sulfate (HS), is involved in various biologic processes. Recently, an association between heparanase and glomerular injury was suggested. The present study examines the involvement of heparanase in the pathogenesis of Adriamycin-induced nephrotic syndrome (ADR-NS) in a mouse model. METHODS: BALB/c wild-type (wt) mice and heparanase overexpressing transgenic mice (hpa-TG) were tail-vein injected with either Adriamycin (ADR, 10 mg/kg) or vehicle. Albuminuria was investigated at days 0, 7, and 14 thereafter. Mice were sacrificed at day 15, and kidneys were harvested for various analyses: structure and ultrastructure alterations, podocyte proteins expression, and heparanase enzymatic activity. RESULTS: ADR-injected wt mice developed severe albuminuria, while ADR-hpa-TG mice showed only a mild elevation in urinary albumin excretion. In parallel, light microscopy of stained cross sections of kidneys from ADR-injected wt mice, but not hpa-TG mice, showed mild to severe glomerular and tubular damage. Western blot and immunofluorescence analyses revealed significant reduction in nephrin and podocin protein expression in ADR-wt mice, but not in ADR-hpa-TG mice. These results were substantiated by electron-microscopy findings showing massive foot process effacement in injected ADR-wt mice, in contrast to largely preserved integrity of podocyte architecture in ADR-hpa-TG mice. CONCLUSIONS: Our results suggest that heparanase may play a nephroprotective role in ADR-NS, most likely independently of HS degradation. Moreover, hpa-TG mice comprise an invaluable in vivo platform to investigate the interplay between heparanase and glomerular injury.

Heparanase procoagulant activity is elevated in women using oral contraceptives.

STUDY QUESTION: What is the effect of estrogen on heparanase procogulant activity? SUMMARY ANSWER: Estrogen increases heparanase procoagulant activity. WHAT IS KNOWN ALREADY: Estrogen therapy increases the risk of thrombosis and was previously found to up-regulate heparanase expression. Heparanase is involved in angiogenesis and metastasis, and has been shown to form a complex with tissue factor (TF) and also shown to enhance the generation of factor Xa. STUDY DESIGN, SIZE, DURATION: A case-control study. Thirty-four healthy women using oral contraceptives (OC) and 41 women not using hormonal therapy and not pregnant per history were enrolled, over a 5-month period, at the Rambam Medical Center, Haifa, Israel. In vitro, estrogen receptor-positive (MCF-7) and -negative (MDA-231) cell lines were incubated with estrogen, tamoxifen and ICI-182.780 a pure estrogen receptor antagonist. The cell medium was evaluated for TF/heparanase complex activity, TF activity and heparanase procoagulant activity by chromogenic substrate. PARTICIPANTS/MATERIALS, SETTING, METHODS: Exclusion criteria included age <18 years, post-menopausal women, concomitant medications other than supplement minerals and vitamins, acute or chronic illness. MAIN RESULTS AND THE ROLE OF CHANCE: The study demonstrates increased risk of high heparanase procoagulant activity in OC users. When a cutoff level of 0.25 (absorbance 405-490 nm) was set, the odds ratio was 131 (P < 0.0001). When all results were studied by quartiles, in quartiles 3 and 4 the results were almost exclusively of the OC users (P < 0.0001). In cell cultures, estrogen and tamoxifen increased heparanase procoagulant activity in the medium of estrogen receptor-positive (MCF-7) cells. LIMITATIONS, REASONS FOR CAUTION: The main limitation of the current study is that the two estrogens given to the women and cell cultures, ethinyl estradiol (EE) and 17-ß-estradiol (E2), respectively, may have different effects on the coagulation system, although an increase in heparanase procoagulant activity was demonstrated in both of them. Although the sample size of the study group was limited, significant differences in the activation of the extrinsic coagulation pathway were demonstrated. WIDER IMPLICATIONS OF THE FINDINGS: The clinical relevance of the heparanase procoagulant activity assay as a screening tool in thrombophilia work-up should further be elucidated.

Macrophage activation by heparanase is mediated by TLR-2 and TLR-4 and associates with plaque progression.

OBJECTIVE: Factors and mechanisms that activate macrophages in atherosclerotic plaques are incompletely understood. We examined the capacity of heparanase to activate macrophages. METHODS AND RESULTS: Highly purified heparanase was added to mouse peritoneal macrophages and macrophage-like J774 cells, and the levels of tumor necrosis factor-α, matrix metalloproteinase-9, interlukin-1, and monocyte chemotactic protein-1 were evaluated by ELISA. Gene expression was determined by RT-PCR. Cells collected from Toll-like receptor-2 and Toll-like receptor-4 knockout mice were evaluated similarly. Heparanase levels in the plasma of patients with acute myocardial infarction, stable angina, and healthy subjects were determined by ELISA. Immunohistochemistry was applied to detect the expression of heparanase in control specimens and specimens of patients with stable angina or acute myocardial infarction. Addition or overexpression of heparanase variants resulted in marked increase in tumor necrosis factor-α, matrix metalloproteinase-9, interlukin-1, and monocyte chemotactic protein-1 levels. Mouse peritoneal macrophages harvested from Toll-like receptor-2 or Toll-like receptor-4 knockout mice were not activated by heparanase. Plasma heparanase level was higher in patients with acute myocardial infarction, compared with patients with stable angina and healthy subjects. Pathologic coronary specimens obtained from vulnerable plaques showed increased heparanase staining compared with specimens of stable plaque and controls. CONCLUSIONS: Heparanase activates macrophages, resulting in marked induction of cytokine expression associated with plaque progression toward vulnerability.

Heparanase role in the treatment of avascular necrosis of femur head.

BACKGROUND: Idiopathic avascular necrosis (AVN) of bone causes significant morbidity in adults although the pathophysiology is unknown. The present treatment options include systemic biphosphonate therapy and local bone drilling decompression, ameliorating the healing process and their by render the weight bearing femur head less vulnerable to collapse. In the present study we demonstrate the involvement of heparanase in AVN and in the acceptable treatments. METHODS: 56 female rats were studied. In 8 control rats AVN was induced by ligamentum teres ligation of the right femur while the left femur remained intact. In the rest of the rats, in addition to right femur AVN, treatment was added by subcutaneous biphosphonate therapy, femoral head drilling or combination of the treatments. All rats were scarified after 6weeks. Immunostaining of the femur heads were performed to heparanase, tissue factor pathway inhibitor (TFPI), tissue factor (TF) and hematoxylin-eosin. RESULTS: Staining of heparanase, TFPI and TF were most prominent in the bone-marrow tissue of the femur heads. Staining by hematoxylin-eosin revealed damaged femur heads with prominent heparanase and TFPI staining in the femur with AVN compared to the contra lateral side of the same rat. No difference was found in the TF staining between the two sides. In the drilling and / or biphosphonate therapy groups, in contrast to the control group, femur heads were preserved with no significant difference in heparanase and TFPI staining between the two sides. CONCLUSIONS: Heparanase and TFPI are locally elevated in the process of AVN and are normalized by the acceptable treatments. Inhibition of heparanase by heparins can potentially improve the nowadays therapy modalities.

Increased heparanase level and procoagulant activity in orthopedic surgery patients receiving prophylactic dose of enoxaparin.

BACKGROUND: Orthopedic hip and knee surgeries are followed by a hypercoagulable state. Heparanase is implicated in inflammation, coagulation activation and angiogenesis. Recently, heparanase was shown to directly interact with tissue factor (TF) and to enhance the generation of factor Xa (Nadir et al., Haematologica, 2010). In addition, an assay assessing heparanase procoagulant activity has been lately developed (Nadir et al., Thromb Res, 2011). In the present study heparanase level and procoagulant activity in patients undergoing orthopedic surgery were assessed. METHODS: The study group included 50 orthopedic patients. 31 patients underwent hip surgery and 19 had knee operation. 15 individuals suffered from traumatic hip fractures and 35 had osteoarthrosis of hip or knee joints. All patients received prophylactic dose of enoxaparin starting 6-8 hours post operation and lasting for 5 weeks. Plasma samples were drawn preoperatively and at 1 hour, 1 week and 1 month post operation. Samples were tested for heparanase levels by ELISA and TF/heparanase complex activity, TF activity, heparanase procoagulant activity, factor Xa and thrombin levels using chromogenic substrates. RESULTS: Heparanase levels were significantly higher 1 hour and 1 week post operatively compared to preoperative levels (p<0.05, p<0.005, respectively). The most dramatic changes were observed in heparanase procoagulant activity reaching a 2 fold increase 1 week postoperatively and 1.7 fold increase 1month after surgery (p<0.0001, p<0.0001, respectively). Levels of factor Xa and thrombin did not significantly change. CONCLUSIONS: Heparanase is involved in coagulation activation of orthopedic surgery patients. Heparanase procoagulant activity is highest 1 week postoperatively and remains high 1month after operation. Considering extending prophylactic anticoagulant therapy or evaluating heparanase procoagulant activity may potentially prevent late thrombotic events.