A role for von Willebrand factor in Streptococcus sanguis-induced platelet activation

Abstract We recently reported that after activation of human platelets by thrombin, glycoprotein (GP) Ib-IX complexes are translocated to the surface-connected canalicular system (SCCS) (Blood 76:1503, 1990). As GPIb is a major receptor for von Willebrand factor (vWF) in platelet adhesion, we have now examined the consequences of thrombin activation on the organization of vWF bound to GPIb on the platelet surface. Studies were performed using monoclonal or polyclonal antibodies in either immunogold staining and electron microscopy (Au-EM) or in flow cytometry. When unstirred platelet-rich plasma was incubated with ristocetin, bound vWF was located by Au-EM as discrete masses regularly distributed over the cell surface. Platelets from a patient with Glanzmann's thrombasthenia, lacking GPIIb-IIIa complexes, gave a similar pattern, confirming that this represented binding to GPIb. That ristocetin was not precipitating vWF before their binding to the platelets was shown by the detection of similar masses on the surface of platelets of a patient with type IIB von Willebrand disease. Experiments were continued using washed normal platelets incubated in Tyrode-EDTA, the purpose of the EDTA being to limit the surface expression of endogenous vWF after platelet stimulation. Under these conditions, platelets were treated with ristocetin for 5 minutes at 37 degrees C in the presence of increasing amounts of purified vWF. This was followed by incubation with thrombin (0.5 U/mL) for periods of up to 10 minutes. Flow cytometry showed a time-dependent loss in the surface expression of vWF bound to GPIb and these changes were confirmed by Au-EM. In particular, immunogold staining performed on ultrathin sections showed that the bulk of the vWF was being cleared to internal membrane systems. Surface clearance of vWF during thrombin- induced platelet activation is a potential mechanism for regulating platelet adhesivity.

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Recurrent Arterial Thrombosis Linked to Autoimmune Antibodies Enhancing von Willebrand Factor Binding to Platelets and Inducing FcγRII Receptor-Mediated Platelet Activation

Blood ◽

10.1182/blood.v91.8.2810.2810_2810_2817 ◽

1998 ◽

Vol 91 (8) ◽

pp. 2810-2817 ◽

Cited By ~ 15

Author(s):

Marc F. Hoylaerts ◽

Chantal Thys ◽

Jef Arnout ◽

Jos Vermylen

Keyword(s):

Platelet Activation ◽

Von Willebrand Factor ◽

Low Dose ◽

Antithyroid Drug ◽

Fetal Loss ◽

Thyroid Peroxidase ◽

Spontaneous Aggregation ◽

Von Willebrand ◽

Induced Aggregation ◽

Willebrand Factor

A patient with a history of recurrent late fetal loss associated with multiple placental infarcts and cerebrovascular ischemia at the age of 36, followed a year later by a myocardial infarction, was referred for further investigation. Coronary angiography was normal. Antinuclear factor, lupus anticoagulant, anticardiolipin antibodies, and other thrombophilia parameters were negative, but there was moderate hyperthyroidism with positive thyroid peroxidase antibodies. Platelet numbers and von Willebrand factor (vWF) were normal. Her platelets showed spontaneous aggregation that disappeared with aspirin intake. However, aggregation still was induced by low levels of ristocetin (0.3 to 0.5 mg/mL). The low-dose ristocetin aggregation in patient platelet-rich plasma (PRP) was completely blocked by neutralizing antiglycoprotein Ib (GPIb) and anti-vWF antibodies. The monoclonal anti-FcγRII receptor antibody IV.3 inhibited partly, which suggests that PRP aggregation by low-dose ristocetin was elicited by vWF-immunoglobulin (Ig) complexes. Upon addition to washed human platelets, with vWF (10 μg/mL), purified patient Igs dose-dependently enhanced ristocetin (0.15 mg/mL)-induced aggregation between 0 and 500 μg/mL, an effect that disappeared again above 1 mg/mL. Aggregation was dependent on the vWF concentration and was blocked by IV.3 or neutralizing anti-GPIb or anti-vWF antibodies. The spontaneous aggregation of normal platelets resuspended in patient plasma could be inhibited totally by IV.3 and partially by neutralizing anti-GPIb or anti-vWF antibodies. Perfusion with normal anticoagulated blood, enriched with 10% of control or patient plasma, over surfaces coated with vWF showed increased platelet adhesion and activation in the presence of patient antibodies. Treatment of the patient with the antithyroid drug thiamazol and temporary corticosteroids, aspirin, and ticlopidine did not correct the platelet hypersensitivity to ristocetin. These observations suggest that some autoantibodies to vWF may both enhance vWF binding to platelets and cause platelet activation through binding to the FcγRII receptor, and thereby may be responsible for a new form of antibody-mediated thrombosis.

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A role for p38 MAP kinase in platelet activation by von Willebrand Factor

Thrombosis and Haemostasis ◽

10.1160/th03-02-0083 ◽

2004 ◽

Vol 91 (01) ◽

pp. 102-110 ◽

Cited By ~ 41

Author(s):

Ilaria Canobbio ◽

Stefania Reineri ◽

Fabiola Sinigaglia ◽

Cesare Balduini ◽

Mauro Torti

Keyword(s):

Arachidonic Acid ◽

Phospholipase A2 ◽

Map Kinase ◽

Platelet Activation ◽

Von Willebrand Factor ◽

P38 Map Kinase ◽

Cyclooxygenase Inhibitors ◽

Von Willebrand ◽

Willebrand Factor ◽

Stimulation Of

SummaryPlatelet activation induced by von Willebrand factor (VWF) binding to the membrane GPIb-IX-V receptor involves multiple signal transduction pathways. Among these, recruitment and activation of the FcγRIIA and stimulation of phospholipase A2 represent independent events equally essential to support a complete platelet response. Phospholipase A2 is activated by calcium and by phosphorylation through MAP kinases. In this work, we found that VWF stimulated the rapid and sustained phosphorylation of p38 MAP kinase (p38MAPK). In vitro kinase assay revealed that VWF-stimulated phosphorylation of p38MAPK was associated with increased kinase activity. Binding of VWF to GPIb-IX-V, but not to integrin αIIbβ3, was required to support phosphorylation of p38MAPK. Neither the blockade of the membrane FcγRIIA by a specific monoclonal antibody or the prevention of thromboxane A2 synthesis by cyclooxygenase inhibitors affected VWF-induced p38MAPK activation. However, phosphorylation of p38MAPK was prevented by the tyrosine kinase Syk inhibitor piceatannol. Treatment of platelets with the p38MAPK inhibitor SB203580 totally prevented VWFstimulated platelet aggregation. Moreover, release of arachidonic acid induced by VWF was strongly impaired by inhibition of p38MAPK. We also found thatVWF induced phosphorylation of cytosolic phospholipase A2, and that this process was prevented by the p38MAPK inhibitor SB203580.These results demonstrate that p38MAPK is a key element in the FcγRIIA-independent pathway for VWF-induced platelet activation, and is involved in the stimulation of phospholipase A2 and arachidonic acid release.

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Prognostic value of plasma soluble P-selectin and von Willebrand factor as indices of platelet activation and endothelial damage/dysfunction in high-risk patients with hypertension: a sub-study of the Anglo-Scandinavian Cardiac Outcomes Trial

Journal of Internal Medicine ◽

10.1111/j.1365-2796.2007.01770.x ◽

2007 ◽

Vol 261 (4) ◽

pp. 384-391 ◽

Cited By ~ 24

Author(s):

G. I. Varughese ◽

J. V. Patel ◽

J. Tomson ◽

A. D. Blann ◽

E. A. Hughes ◽

...

Keyword(s):

High Risk ◽

Platelet Activation ◽

Von Willebrand Factor ◽

Prognostic Value ◽

Endothelial Damage ◽

High Risk Patients ◽

Cardiac Outcomes ◽

Risk Patients ◽

Von Willebrand ◽

Willebrand Factor

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Platelet Activation and von Willebrand Factor Binding to Platelets in Newborn Infants with Central Venous Lines

Acta Haematologica ◽

10.1159/000097461 ◽

2006 ◽

Vol 117 (3) ◽

pp. 145-148 ◽

Cited By ~ 7

Author(s):

M. Schmugge ◽

K.W.A. Bang ◽

V.S. Blanchette ◽

M. Albisetti ◽

B.L. Connolly ◽

...

Keyword(s):

Platelet Activation ◽

Von Willebrand Factor ◽

Newborn Infants ◽

Central Venous ◽

Factor Binding ◽

Von Willebrand ◽

Willebrand Factor

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Filamin A binding to the cytoplasmic tail of glycoprotein Ibα regulates von Willebrand factor–induced platelet activation

Blood ◽

10.1182/blood-2002-12-3805 ◽

2003 ◽

Vol 102 (6) ◽

pp. 2122-2129 ◽

Cited By ~ 57

Author(s):

Shuju Feng ◽

Julio C. Reséndiz ◽

Xin Lu ◽

Michael H. Kroll

Keyword(s):

Shear Stress ◽

Platelet Aggregation ◽

Fusion Protein ◽

Platelet Activation ◽

Von Willebrand Factor ◽

Cytoplasmic Tail ◽

Cytoplasmic Domain ◽

Filamin A ◽

Von Willebrand ◽

Willebrand Factor

Abstract We examined the hypothesis that filamin A binding to the cytoplasmic tail of platelet glycoprotein Ibα (GpIbα) is regulated by pathologic shear stress and modulates von Willebrand factor (VWF)–induced platelet activation. To begin, we examined filamin binding to GpIbα in Chinese hamster ovary cells coexpressing mutant human GpIb-IX and wild-type human filamin A. We observed that many different deletions and truncations N-terminal to GpIbα's cytoplasmic domain residue 594 disrupted filamin A binding, but that binding was unaffected by 14 different point mutations in hydrophilic residues between amino acids 557 and 593. To try to narrow GpIbα's filamin A–binding domain, we next measured the effect of several cytoplasmic domain peptides on human filamin A binding to a GST-GpIbα cytoplasmic domain fusion protein. One peptide (residues 557-575; designated “A4 peptide”) inhibited filamin A binding to the GST-GpIbα cytoplasmic domain fusion protein and competed with GpIbα for binding to filamin A. When the A4 peptide was delivered to intact human platelets using a carrier peptide, we observed the dose-dependent inhibition of VWF-induced platelet aggregation in response to both ristocetin and shear stress. The effect of the A4 peptide on shear-induced platelet aggregation was accompanied by the attenuation of shear-induced filamin A binding to GpIbα and diminished shear-dependent protein tyrosine phosphorylation. These results suggest that shear-dependent VWF-induced platelet activation affects filamin A binding to GpIb-IX-V, and that filamin A binding to the cytoplasmic tail of GpIbα regulates proaggregatory tyrosine kinase signaling.

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Effects of von Willebrand factor concentration and platelet collision on shear-induced platelet activation

Thrombosis and Haemostasis ◽

10.1160/th07-03-0222 ◽

2008 ◽

Vol 100 (07) ◽

pp. 60-68 ◽

Cited By ~ 2

Author(s):

Zhenyue Gao ◽

Fang Liu ◽

Ziqiang Yu ◽

Xia Bai ◽

Fengyuan Zhuang ◽

...

Keyword(s):

Platelet Activation ◽

Von Willebrand Factor ◽

Annexin V ◽

Flow Chamber ◽

Platelet Glycoprotein ◽

High Shear ◽

Shear Rates ◽

Von Willebrand ◽

The Impact ◽

Willebrand Factor

SummaryThe binding of plasma von Willebrand factor (vWF) to platelet glycoprotein (GP) Ibα in a high shear stress field, and subsequent integrin-GPIIb/IIIa-vWF conjunction induces platelet aggregation (SIPA). However, the specific biomechanical mechanism of the vWF-GPIb interaction still remains to be elucidated. A parallel-plate rectangular flow chamber was built to simulate a stenopeic artery flow pattern. Using the flow chamber, we examined shear- induced platelet activation (SIPAct) at different vWF concentrations (5–25 µg/ml) and several simulated stenotic high shear rates. P-selectin expression on the platelets and annexin V binding to the platelets were used as two markers of platelet activation. At different localized shear rates (3,000 s-1–9,500 s-1), the percentage of annexin V and P-selectin positive cells increased from 8.3 ± 0.4% to 22.3 ± 1.8% ( p 0.05) and from 17.4 ± 0.5% to 33.5 ± 2.5% (p 0.05),respectively. As the vWF concentration increased from 5 µg/ml to 25 µg/ml, the annexinV binding rate increased from 7.2 ± 0.6% to 53.4 ± 3.8% (p 0.05), and P-selectin expression increased from 16.5 ± 1.2% to 65.9 ± 5.2% (p 0.05). A test in a uniform shear field using cone-plate viscometer rheometry showed that the platelet activation rate was proportional to the platelet concentration. This result suggests that platelet collision is one of the impact factors of SIPAct.

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