Proteolysis of von Willebrand Factor and Shear Stress–Induced Platelet Aggregation in Patients With Aortic Valve Stenosis

SummaryPorcine von Willebrand factor (P-vWF) binds to human platelet glycoprotein (GP) lb and, upon stirring (1500 rpm/min) at 37° C, induces, in a dose-dependent manner, a transmembrane flux of Ca2+ ions and platelet aggregation with an increase in their intracellular concentration. The inhibition of P-vWF binding to GP lb, obtained with anti GP lb monoclonal antibody (LJ-Ib1), inhibits the increase of intracellular Ca2+ concentration ([Ca2+]i) and platelet aggregation. This effect is not observed with LJ-Ib10, an anti GP lb monoclonal antibody which does not inhibit the vWF binding to GP lb. An anti GP Ilb-IIIa monoclonal antibody (LJ-CP8) shown to inhibit the binding of both vWF and fibrinogen to the GP IIb-IIIa complex, had only a slight effect on the [Ca2+]i rise elicited by the addition of P-vWF. No inhibition was also observed with a different anti GP IIb-IIIa monoclonal antibody (LJ-P5), shown to block the binding of vWF and not that of fibrinogen to the GP IIb-IIIa complex. PGE1, apyrase and indomethacin show a minimal effect on [Ca2+]i rise, while EGTA completely blocks it. The GP lb occupancy by recombinant vWF fragment rvWF445-733 completely inhibits the increase of [Ca2+]i and large aggregates formation. Our results suggest that, in analogy to what is seen with human vWF under high shear stress, the binding of P-vWF to platelet GP lb, at low shear stress and through the formation of aggregates of an appropriate size, induces a transmembrane flux of Ca2+, independently from platelet cyclooxy-genase metabolism, perhaps through a receptor dependent calcium channel. The increase in [Ca2+]i may act as an intracellular message and cause the activation of the GP IIb-IIIa complex.

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Platelet Aggregation Induced by a Monoclonal Antibody to the A1 Domain of von Willebrand Factor

Blood ◽

10.1182/blood.v91.10.3792.3792_3792_3799 ◽

1998 ◽

Vol 91 (10) ◽

pp. 3792-3799 ◽

Cited By ~ 3

Author(s):

Hilde Depraetere ◽

Nadine Ajzenberg ◽

Jean-Pierre Girma ◽

Catherine Lacombe ◽

Dominique Meyer ◽

...

Keyword(s):

Shear Stress ◽

Platelet Aggregation ◽

Von Willebrand Factor ◽

Inhibitory Effect ◽

Platelet Glycoprotein ◽

Rotational Viscometer ◽

Induce Platelet Aggregation ◽

Static Conditions ◽

Von Willebrand ◽

Willebrand Factor

Shear-induced platelet aggregation (SIPA) involves von Willebrand Factor (vWF) binding to platelet glycoprotein (GP)Ib at high shear stress, followed by the activation of αIIbβ3. The purpose of this study was to determine the vWF sequences involved in SIPA by using monoclonal antibodies (MoAbs) to vWF known to interfere with its binding to GPIb and to αIIbβ3. Washed platelets were exposed to shear rates between 100 and 4,000 seconds−1 in a rotational viscometer. SIPA was quantitated by flow cytometry as the disappearance of single platelets (DSP) in the sheared sample in the presence of vWF, relative to a control in the absence of shear and vWF. At a shear rate of 4,000 seconds−1, DSP was increased from 5.9% ± 3.5% in the absence of vWF to 32.7% ± 6.3% in the presence of vWF. This increase in SIPA was not associated with an elevation of P-selectin expression. vWF-dependent SIPA was completely abolished by MoAb 6D1 to GPIb and partially inhibited by MoAb 10E5 to αIIbβ3. Three MoAbs to vWF were compared for their effect on SIPA at 4,000 seconds−1 in the presence of vWF: MoAb 328, known to block vWF binding to GPIb in the presence of ristocetin, MoAb 724 blocking vWF binding to GPIb in the presence of botrocetin, and MoAb 9, an inhibitor of vWF binding to αIIbβ3. Similar to the effect of MoAb 6D1, MoAb 328 completely inhibited the effect of vWF, whereas MoAb 9 had a partial inhibitory effect, as MoAb 10E5 did. In contrast, MoAb 724, as well as its F(ab′)2 fragments, promoted shear-dependent platelet aggregation (165% of the DSP value obtained in the absence of MoAb 724), indicating that MoAb 724 was responsible for an enhanced aggregation, which was independent of binding to the platelet Fcγ receptor. In addition, the enhancement of aggregation induced by MoAb 724 was abrogated by MoAb 6D1 or 10E5 to the level of SIPA obtained in the presence of vWF incubated with a control MoAb to vWF. Finally, the activating effect of MoAb 724 was also found under static conditions at ristocetin concentrations too low to induce platelet aggregation. Our results suggested that on binding to a botrocetin-binding site on vWF, MoAb 724 mimics the effect of botrocetin by inducing an active conformation of vWF that is more sensitive to shear stress or to low ristocetin concentration.

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Von Willebrand factor ratio as a risk factor for bleeding in aortic valve stenosis replacement surgery

10.1055/s-0041-1728103 ◽

2021 ◽

Author(s):

M Wolny ◽

C Brandenburger ◽

V Unislawski ◽

U Budde ◽

A Zittermann ◽

...

Keyword(s):

Risk Factor ◽

Aortic Valve ◽

Aortic Valve Stenosis ◽

Von Willebrand Factor ◽

Replacement Surgery ◽

Factor Ratio ◽

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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Platelet Aggregation Induced by a Monoclonal Antibody to the A1 Domain of von Willebrand Factor

Blood ◽

10.1182/blood.v91.10.3792 ◽

1998 ◽

Vol 91 (10) ◽

pp. 3792-3799 ◽

Cited By ~ 20

Author(s):

Hilde Depraetere ◽

Nadine Ajzenberg ◽

Jean-Pierre Girma ◽

Catherine Lacombe ◽

Dominique Meyer ◽

...

Keyword(s):

Shear Stress ◽

Platelet Aggregation ◽

Von Willebrand Factor ◽

Inhibitory Effect ◽

Platelet Glycoprotein ◽

Rotational Viscometer ◽

Induce Platelet Aggregation ◽

Static Conditions ◽

Von Willebrand ◽

Willebrand Factor

AbstractShear-induced platelet aggregation (SIPA) involves von Willebrand Factor (vWF) binding to platelet glycoprotein (GP)Ib at high shear stress, followed by the activation of αIIbβ3. The purpose of this study was to determine the vWF sequences involved in SIPA by using monoclonal antibodies (MoAbs) to vWF known to interfere with its binding to GPIb and to αIIbβ3. Washed platelets were exposed to shear rates between 100 and 4,000 seconds−1 in a rotational viscometer. SIPA was quantitated by flow cytometry as the disappearance of single platelets (DSP) in the sheared sample in the presence of vWF, relative to a control in the absence of shear and vWF. At a shear rate of 4,000 seconds−1, DSP was increased from 5.9% ± 3.5% in the absence of vWF to 32.7% ± 6.3% in the presence of vWF. This increase in SIPA was not associated with an elevation of P-selectin expression. vWF-dependent SIPA was completely abolished by MoAb 6D1 to GPIb and partially inhibited by MoAb 10E5 to αIIbβ3. Three MoAbs to vWF were compared for their effect on SIPA at 4,000 seconds−1 in the presence of vWF: MoAb 328, known to block vWF binding to GPIb in the presence of ristocetin, MoAb 724 blocking vWF binding to GPIb in the presence of botrocetin, and MoAb 9, an inhibitor of vWF binding to αIIbβ3. Similar to the effect of MoAb 6D1, MoAb 328 completely inhibited the effect of vWF, whereas MoAb 9 had a partial inhibitory effect, as MoAb 10E5 did. In contrast, MoAb 724, as well as its F(ab′)2 fragments, promoted shear-dependent platelet aggregation (165% of the DSP value obtained in the absence of MoAb 724), indicating that MoAb 724 was responsible for an enhanced aggregation, which was independent of binding to the platelet Fcγ receptor. In addition, the enhancement of aggregation induced by MoAb 724 was abrogated by MoAb 6D1 or 10E5 to the level of SIPA obtained in the presence of vWF incubated with a control MoAb to vWF. Finally, the activating effect of MoAb 724 was also found under static conditions at ristocetin concentrations too low to induce platelet aggregation. Our results suggested that on binding to a botrocetin-binding site on vWF, MoAb 724 mimics the effect of botrocetin by inducing an active conformation of vWF that is more sensitive to shear stress or to low ristocetin concentration.

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von Willebrand factor abnormalities in aortic valve stenosis: Pathophysiology and impact on bleeding

Thrombosis and Haemostasis ◽

10.1160/th10-10-0634 ◽

2011 ◽

Vol 106 (07) ◽

pp. 58-66 ◽

Cited By ~ 36

Author(s):

Sandro Sponga ◽

Elena Pontara ◽

Maria Grazia Cattini ◽

Cristina Basso ◽

Gaetano Thiene ◽

...

Keyword(s):

Aortic Valve ◽

Aortic Valve Stenosis ◽

Von Willebrand Factor ◽

Severe Aortic Stenosis ◽

Valve Disease ◽

Minor Bleeding ◽

Acquired Von Willebrand Syndrome ◽

Rheumatic Valve Disease ◽

Von Willebrand ◽

Willebrand Factor

SummaryAcquired von Willebrand syndrome (AVWS) may complicate severe aortic valve stenosis, due to a reduction in the haemostatically more efficient large von Willebrand factor (VWF) multimers. This study was designed to analyse the relevance of VWF abnormalities and haemorrhagic diathesis in severe aortic valve stenosis. Forty-one consecutive patients undergoing valve replacement were investigated: seven had minor bleeding symptoms in their recent history; 10 (24.3%) had a reduced VWF collagen binding (VWF:CB) to VWF antigen ratio, and 33 (80.5%) had a decrease in large VWF multimers. The shortage of large multimers was not associated with any accumulation of small VWF multimers (apparently ruling out any increased VWF proteolysis), nor was there any increase in VWF propeptide, which excludes a shorter VWF survival. The risk of developing VWF abnormalities was higher in patients with rheumatic valve disease than in degenerative cases (p=0.025) and in valves with <50% of residual endothelial cells (p=0.004). Bleeders differed from non-bleeders in that they had a higher mean transvalvular gradient and a more marked decrease in large VWF multimers. VWF abnormalities did not exacerbate peri-operative blood loss, however – a finding consistent with the full correction of these VWF abnormalities, seen already on the first postoperative day and persisting for up to six months after surgery. According to the data obtained in our cohort of patients VWF abnormalities are common in severe aortic stenosis, particularly in cases of rheumatic valve disease, but loss of the largest multimers does not seem to cause clinical bleeding in most patients.

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Shear-induced platelet aggregation requires von Willebrand factor and platelet membrane glycoproteins Ib and IIb-IIIa

Blood ◽

10.1182/blood.v69.2.625.bloodjournal692625 ◽

1987 ◽

Vol 69 (2) ◽

pp. 625-628 ◽

Cited By ~ 1

Author(s):

DM Peterson ◽

NA Stathopoulos ◽

TD Giorgio ◽

JD Hellums ◽

JL Moake

Keyword(s):

Shear Stress ◽

Platelet Aggregation ◽

Von Willebrand Factor ◽

Platelet Rich Plasma ◽

Shear Stresses ◽

Membrane Glycoprotein ◽

Membrane Glycoproteins ◽

Von Willebrand ◽

Induced Aggregation ◽

Willebrand Factor

Different types of platelets in various types of plasma were subjected to levels of shear stress that produce irreversible platelet aggregation in normal platelet-rich plasma (PRP). At shear stresses of 90 or 180 dyne/cm2 applied for 30 seconds or five minutes, aggregation was either absent or only transient and reversible using severe von Willebrand's disease (vWD) PRP (less than 1% von Willebrand factor, vWF); Bernard-Soulier syndrome (BSS) PRP (platelets deficient in the membrane glycoprotein Ib, GPIb); normal PRP plus monoclonal antibody (MoAb) to GPIb; thrombasthenic PRP (platelets deficient in membrane glycoprotein IIb-IIIa complex, GPIIb-IIIa); and normal PRP plus MoAb to GPIIb-IIIa. Shear-induced aggregation was inhibited under the above conditions, even though the platelets were activated to release their granular contents. Sheared normal platelets in vWD plasma aggregated in response to added vWF. These studies demonstrate that the formation of stable platelet aggregates under conditions of high shear requires vWF and the availability of both GPIb and GPIIb-IIIa on platelet membranes. The experiments demonstrate that vWF-platelet interactions can occur in the absence of artificial agonists or chemical modification of vWF. They suggest a possible mechanism for platelet aggregation in stenosed or partially obstructed arterial vessels in which the platelets are subjected to relatively high levels of shear stress.

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Shear-induced platelet aggregation requires von Willebrand factor and platelet membrane glycoproteins Ib and IIb-IIIa

Blood ◽

10.1182/blood.v69.2.625.625 ◽

1987 ◽

Vol 69 (2) ◽

pp. 625-628 ◽

Cited By ~ 211

Author(s):

DM Peterson ◽

NA Stathopoulos ◽

TD Giorgio ◽

JD Hellums ◽

JL Moake

Keyword(s):

Shear Stress ◽

Platelet Aggregation ◽

Von Willebrand Factor ◽

Platelet Rich Plasma ◽

Shear Stresses ◽

Membrane Glycoprotein ◽

Membrane Glycoproteins ◽

Von Willebrand ◽

Induced Aggregation ◽

Willebrand Factor

Abstract Different types of platelets in various types of plasma were subjected to levels of shear stress that produce irreversible platelet aggregation in normal platelet-rich plasma (PRP). At shear stresses of 90 or 180 dyne/cm2 applied for 30 seconds or five minutes, aggregation was either absent or only transient and reversible using severe von Willebrand's disease (vWD) PRP (less than 1% von Willebrand factor, vWF); Bernard-Soulier syndrome (BSS) PRP (platelets deficient in the membrane glycoprotein Ib, GPIb); normal PRP plus monoclonal antibody (MoAb) to GPIb; thrombasthenic PRP (platelets deficient in membrane glycoprotein IIb-IIIa complex, GPIIb-IIIa); and normal PRP plus MoAb to GPIIb-IIIa. Shear-induced aggregation was inhibited under the above conditions, even though the platelets were activated to release their granular contents. Sheared normal platelets in vWD plasma aggregated in response to added vWF. These studies demonstrate that the formation of stable platelet aggregates under conditions of high shear requires vWF and the availability of both GPIb and GPIIb-IIIa on platelet membranes. The experiments demonstrate that vWF-platelet interactions can occur in the absence of artificial agonists or chemical modification of vWF. They suggest a possible mechanism for platelet aggregation in stenosed or partially obstructed arterial vessels in which the platelets are subjected to relatively high levels of shear stress.

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