scholarly journals 418 Ultrasound molecular imaging of the role of von willebrand factor-mediated platelet adhesion in atherogenesis

2020 ◽  
Vol 21 (Supplement_1) ◽  
Author(s):  
K Ozawa ◽  
M Muller ◽  
O Varlamov ◽  
W Packwood ◽  
A Xie ◽  
...  
Keyword(s):  
Molecular Imaging ◽  
Von Willebrand Factor ◽  
Platelet Adhesion ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Aortic Distensibility ◽  
Research Fellowship ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract Funding Acknowledgements JSPS Overseas Research Fellowship Background Platelets are known to be both pro-inflammatory and pro-mitogenic. However, the role of platelet-endothelial interactions in the initiation and growth of atherosclerotic lesions is not well understood. Purpose We used contrast-enhanced ultrasound (CEU) molecular imaging of the arterial endothelium to test the hypothesis that platelet attachment to endothelial Von Willebrand Factor (VWF) promotes atherogenesis. Methods We studied wild-type mice (WT), low-density lipoprotein deficient mice fed western diet to produce atherosclerosis (LDLR-/-), and LDLR-/- mice also deficient for ADAMTS-13 (LDLR-/-ADAMTS13-/-) which is the enzyme responsible for proteolytic cleavage of endothelial-associated VWF. Mice were studied at 20 weeks and 30 weeks of age. A subset of LDLR-/- mice were treated with recombinant ADAMTS13 1 hr prior to study. Proximal aortic CEU molecular imaging of P-selectin, vascular cell adhesion molecule (VCAM)-1, von Willebrand factor (VWF), and platelet GPIbα was performed. Aortic distensibility was assessed using high-frequency (30 MHz) transthoracic echocardiography and tail cuff blood pressure systems. NF-κB of aorta was assessed by ELISA kit. Plaque size and composition were assessed by histology. Platelets and macrophage immunohistochemistry were also performed on confocal microscopy. Results Aortic molecular imaging signal for P-selectin, VCAM-1, VWF, and platelet adhesion was significantly higher in LDLR-/- than WT mice, and increased by 2-fold between 20 and 30 wks of age. Signal for VWF and platelet adhesion was abolished 1 h after administration of ADAMTS13, confirming that platelet adhesion was VWF-mediated. At 20 and 30 wks of age, molecular imaging signal for all targets was 2-fold higher (p < 0.01) in LDLR-/-ADAMTS13-/- versus LDLR-/- mice. The LDLR-/-ADAMTS13-/- mice also had lower aortic distensibility (p < 0.05), had a 2-fold higher NF-κB signal (p < 0.05), and had a 2-fold greater total plaque area (p < 0.01). Fluorescent immunohistochemistry confirmed that the LDLR-/-ADAMTS13-/- mice also had greater platelets (p < 0.05) and increased macrophage content (p < 0.05) than LDLR-/- mice in aortic plaque. Conclusion In early to mid-stage atherosclerosis, abnormal regulation of endothelial-associated VWF results in platelet adhesion and secondary up-regulation of endothelial inflammatory adhesion molecules, thereby promoting atherosclerotic plaque progression. These results indicate an important role of platelet-endothelial interactions in early atherogenesis. Abstract 418 Figure

scholarly journals Partial characterization of a binding site for von Willebrand factor on glycocalicin

Blood ◽  
1986 ◽  
Vol 67 (1) ◽  
pp. 19-26 ◽  
Author(s):  
AD Michelson ◽  
J Loscalzo ◽  
B Melnick ◽  
BS Coller ◽  
RI Handin
Keyword(s):  
Binding Site ◽  
Von Willebrand Factor ◽  
Platelet Adhesion ◽  
Binding Activity ◽  
Proteolytic Fragment ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Beta Galactosidase

The binding of von Willebrand factor (vWF) to platelet membrane glycoprotein Ib (GpIb) facilitates platelet adhesion to vascular subendothelium. In this study, we provide evidence that the vWF binding site is on glycocalicin (GC), a proteolytic fragment of GpIb, and we examine the role of the carbohydrate portion of GC on that binding. The binding to platelets of 6D1, a monoclonal antibody that recognizes an epitope on GpIb and blocks ristocetin-induced vWF binding to platelets, was inhibited by purified GC. In addition, purified GC inhibited ristocetin-dependent binding of 125I-labeled vWF to platelets. Since GC contains 60% carbohydrate by weight, we assessed the role of carbohydrate sequences on its interaction with antibody 6D1 and vWF. Based on the known sequence of the major oligosaccharide chain of GC--N- acetyl neuraminic acid, galactose, N-acetyl glucosamine, N-acetyl galactosamine--we treated GC sequentially with neuraminidase, beta- galactosidase, and beta-N-acetylglucosaminidase. Removal of sialic acid and galactose residues did not affect GC binding. Removal of N-acetyl glucosamine residues did not affect GC binding to 6D1 but did decrease the ability of GC to inhibit vWF binding to platelets, increasing the concentration needed to inhibit binding by 50% (IC50) 40-fold. This suggests that a portion of the oligosaccharide chains on GC contributes to the vWF binding activity of this molecule.

scholarly journals Platelet von Willebrand factor: evidence for its involvement in platelet adhesion to collagen

Blood ◽  
1987 ◽  
Vol 70 (4) ◽  
pp. 1214-1217
Author(s):  
E Fressinaud ◽  
D Baruch ◽  
C Rothschild ◽  
HR Baumgartner ◽  
D Meyer
Keyword(s):  
Shear Rate ◽  
Von Willebrand Factor ◽  
Platelet Adhesion ◽  
Von Willebrand Disease ◽  
High Shear ◽  
Shear Rates ◽  
High Shear Rates ◽  
Von Willebrand ◽  
Willebrand Factor

Although it is well established that plasma von Willebrand Factor (vWF) is essential to platelet adhesion to subendothelium at high shear rates, the role of platelet vWF is less clear. We studied the respective role of both plasma and platelet vWF in mediating platelet adhesion to fibrillar collagen in a parallel-plate perfusion chamber. Reconstituted blood containing RBCs, various mixtures of labeled washed platelets and plasma from controls or five patients with severe von Willebrand disease (vWD), was perfused through the chamber for five minutes at a shear rate of 1,600 s-1. Platelet-collagen interactions were estimated by counting the radioactivity in deposited platelets and by quantitative morphometry. When the perfusate consisted of normal platelets suspended in normal plasma, platelet deposition on the collagen was 24.7 +/- 3.6 X 10(6)/cm2 (mean +/- SEM, n = 6). Significantly less deposition (16 +/- 2.3) was observed when vWD platelets were substituted for normal platelets. In mixtures containing vWD plasma, significantly greater deposition (9 +/- 2.2) was obtained with normal than with vWD platelets (1 +/- 0.4) demonstrating a role for platelet vWF in mediating the deposition of platelets on collagen. Morphometric analysis confirmed these data. Our findings indicate that platelet, as well as plasma, vWF mediates platelet-collagen interactions at a high shear rate.

The role of platelet von Willebrand factor in platelet adhesion and thrombus formation: a study of 34 patients with various subtypes of type I von Willebrand disease

1994 ◽  
Vol 86 (2) ◽  
pp. 327-332 ◽  
Author(s):  
Edith Fressinaud ◽  
Augusto B. Federici ◽  
Giancarlo Castaman ◽  
Chantal Rothschild ◽  
Francesco Rodeghiero ◽  
...  
Keyword(s):  
Von Willebrand Factor ◽  
Platelet Adhesion ◽  
Thrombus Formation ◽  
Von Willebrand Disease ◽  
Type I ◽  
Von Willebrand ◽  
Willebrand Factor

Microfibrils (MF) Platelet Interaction: Requirement Of Von Willebrand Factor In Platelet Adhesion To A Placenta Microfibrillar Component (PMC)

1981 ◽  
Author(s):  
F Fauvel ◽  
Y J Legrand ◽  
N Gutman ◽  
J P Muh ◽  
G Tobelem ◽  
...  
Keyword(s):  
Von Willebrand Factor ◽  
Platelet Adhesion ◽  
Human Platelets ◽  
Human Artery ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Adhesion Of Platelets ◽  
Aggregation Of Platelets

It has been shown that collagenase resistant arterial microfibrils (MF) are able to interact with platelets and therefore represents, besides collagen, a second thrombogenic structure in the vessel wall. In vitro observation using a PMC purified from the villosities of human placenta by a mechanical non denaturing procedure confirm this interaction between platelets and MF. PMC was homogenous under electron microscope (feltwork of MF with a mean diameter of 120 – 130 A) and was glycoproteic in nature. PMC were able to induce an aggregation of human platelets only if the platelets were in plasma. The role of Von Willebrand factor (F VIII/WF) as a cofactor of the aggregation of platelets by MF has been postulated from the fact that twice washed platelets from normal subject resuspended in PPP obtained from a severe Von Willebrand deficient patient were not aggregated by the PMC. Furthermore, aggregation was restored after resuspension of the same platelets in the PPP of the same patient 30 and 120 minutes after perfusion of cryoprecipitate (40 units F VIII/RA per kg).F VIII/WF mediates platelet adhesion after binding to subendothelium of human artery. Our observation strongly supports the idea that MF are the subendothelial components to which F VIII/WF binds, thus promoting an adhesion of platelets.

A ROLE OF PLATELET MEMBRANE COMPONENTS IN THE INTERACTION OF PLATELET-COLLAGEN-VON WILLEBRAND FACTOR

1987 ◽  
Author(s):  
M Aihara ◽  
S Morimoto ◽  
Y Sawada ◽  
A Kimura ◽  
Y Chiba ◽  
...  
Keyword(s):  
Von Willebrand Factor ◽  
Platelet Adhesion ◽  
Ricinus Communis ◽  
Platelet Membrane ◽  
Silver Stain ◽  
Normal Plasma ◽  
Membrane Components ◽  
Von Willebrand ◽  
Willebrand Factor

To determine a role of platelet membrane components on the interaction of platelet-collagen-von Willebrand factor(vWF), several experimental approaches were used. The adhesion of human fixed washed platelets(FWP) to collagen was decreased after the treatment with Serratia marcescens protease(100 ug/ml), but the collagen cofactor activity(COo) of vWF that enhances the adhesion of FWP to collagen was still present after the digestion. Although the platelet adhesion in the absence of normal plasma was not changed by the addition of monoclonal antibody(M-ab) against platelet membrane glycoprotein(GP) IIb/lIIa(1 0E5, BS Coller), the adhesion was decreased by 30-50% after the treatment of the platelets with 10-100 ug/ml anti-GPIb(6D1, BS Coller). The adhesion of FWP to collagen was inhibited by lectins;the adhesion was 58-75% in the presence of 100-400 ug/ml L. culinaris lectin or weat germ agglutinin and the adhesion was nil in the presence of 100 ug/ml Ricinus communis agglutinin I or 200 ug/ml concanavalin A. By the crossed aff ino-immunoelectrophoresis, the binding of GP Ilb/lIIa in Triton-solubilized platelet supernatant to the collagen spacer gel was observed. When CHAPSO solubilized platelet was applied to the collagen column and the fractions containing adhesion inhibitor were eluated by 0.3M NaCl, Mr of 240K, 220K, 21 OK, 116K, 61K, 54K, 50K and 45K proteins were identified besides the proteins which correspond to thrombospondin, GPIb, GP lib or Ilia by SDS-PAGE(7.5% gel, silver stain). GOo in normal plasma was not changed by anti-GPIIb/lIIa but was decreased to 32-38%by anti-GPIb. M-ab against vWF, CLB-RAg 35(van Mourik), that inhibits the binding of vWF to platelet by ristocetin decreased COo in normal plasma by 70% and CLB-RAg 201 (van Mourik) that inhibits the binding of vWF to collagen did completely inhibit the COo in normal plasma. In conclusion, our data suggest that (1) GPIb is partly involved in the platelet adhesion to collagen; (2) the binding of vWF to collagen is required for the expression of CCo; (3) CCo of vWF is partly mediated though GPIb; and (4) several platelet membrane protein(s) besides GPIb or GPIIb/lIIa may be also involved in both the adhesion of platelets to collagen and CCo of vWF.

scholarly journals High-density lipoprotein modulates thrombosis by preventing von Willebrand factor self-association and subsequent platelet adhesion

Blood ◽  
2016 ◽  
Vol 127 (5) ◽  
pp. 637-645 ◽  
Author(s):  
Dominic W. Chung ◽  
Junmei Chen ◽  
Minhua Ling ◽  
Xiaoyun Fu ◽  
Teri Blevins ◽  
...  
Keyword(s):  
High Density Lipoprotein ◽  
Von Willebrand Factor ◽  
Platelet Adhesion ◽  
Density Lipoprotein ◽  
High Density ◽  
New Approach ◽  
Key Points ◽  
Self Association ◽  
Von Willebrand ◽  
Willebrand Factor

Key Points High-density lipoprotein and its major apolipoprotein ApoA-I prevent von Willebrand factor self-association. Targeting von Willebrand factor self-association could be a new approach to treating thrombotic disorders.

scholarly journals COVID-19 Clot: What Is It? Why in the Lungs? Extracellular Histone, “Auto-Activation” of Prothrombin, Emperipolesis, Megakaryocytes, “Self-Association” of Von Willebrand Factor and Beyond

2020 ◽  
Author(s):  
Nadarajah Varatharajah
Keyword(s):  
Von Willebrand Factor ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Extracellular Dna ◽  
Fibrous Network ◽  
Self Association ◽  
Vascular Occlusions ◽  
Von Willebrand ◽  
Willebrand Factor

COVID-19 thromboembolic disease has brought all of us back to the drawing board. In COVID-19, pre-existing activated endothelium with increased Von Willebrand factor (VWF), low density lipoprotein (LDL) promoting “self-association” and “sticking” of long VWF strings to the vascular endothelial wall, suppressed ADAMTS13 cleavage of VWF, hypoxia induced upregulation and activation of VWF, fibrous network from neutrophil extracellular traps (NETs) with free DNA and histone, all appear to be initiating the thrombogenesis. Worsening complement activation, cytokine storm and resulting endothelial destruction, unregulated thrombogenesis leads to vascular occlusions and hypoxia. At this stage, the presence of abundant extracellular DNA, histone and -defensins appears worse than the SARS-CoV-2 itself. Previously observed in vitro mechanisms like histone “auto-activating” prothrombin, histone activated platelets generating thrombin without FXII, thrombin and plasmin cleaving complement C5 appears highly likely in COVID-19. Megakaryocytes are actively producing platelets in the lungs and appear to play a major role in thrombogenesis of COVID-19 raising suspicion of emperipolesis. This focused review is a compilation of my observations in relation to the pathophysiology of the intravascular environment, mainly in COVID-19 lungs. Pathophysiology based clinical trials are paramount in reducing morbidity and mortality in COVID-19.

scholarly journals On the role of von Willebrand factor in promoting platelet adhesion to fibrin in flowing blood

Blood ◽  
1995 ◽  
Vol 86 (11) ◽  
pp. 4158-4165 ◽  
Author(s):  
SC Endenburg ◽  
RR Hantgan ◽  
L Lindeboom-Blokzijl ◽  
H Lankhof ◽  
WG Jerome ◽  
...  
Keyword(s):  
Binding Site ◽  
Von Willebrand Factor ◽  
Platelet Adhesion ◽  
Enzyme Linked Immunosorbent Assay ◽  
Secondary Interaction ◽  
Shear Rates ◽  
High Shear Rates ◽  
Von Willebrand ◽  
Willebrand Factor

Platelet adhesion to fibrin at high shear rates depends on both the glycoprotein (GP) IIb:IIIa complex and a secondary interaction between GPIb and von Willebrand factor (vWF). This alternative link between platelets and vWF in promoting platelet adhesion to fibrin has been examined in flowing whole blood with a rectangular perfusion chamber. Optimal adhesion required both platelets and vWF, as shown by the following observations. No binding of vWF could be detected when plasma was perfused over a fibrin surface or when coated fibrinogen was incubated with control plasma in an enzyme-linked immunosorbent assay. However, when platelets were present during perfusion, interactions between vWF and fibrin could be visualized with immunoelectron microscopy. Exposure of fibrin surfaces to normal plasma before perfusion with severe von Willebrand's disease blood did not compensate for the presence of plasma vWF necessary for adhesion. vWF mutants in which the GPIIb:IIIa binding site was mutated or the GPIb binding site was deleted showed that vWF only interacts with GPIb on platelets in supporting adhesion to fibrin and not with GPIIb:IIIa. Complementary results were obtained with specific monoclonal antibodies against vWF. Thus, vWF must first bind to platelets before it can interact with fibrin and promote platelet adhesion. Furthermore, only GPIb, but not GPIIb:IIIa is directly involved in this interaction of vWF with platelets.

scholarly journals Partial characterization of a binding site for von Willebrand factor on glycocalicin

Blood ◽  
1986 ◽  
Vol 67 (1) ◽  
pp. 19-26 ◽  
Author(s):  
AD Michelson ◽  
J Loscalzo ◽  
B Melnick ◽  
BS Coller ◽  
RI Handin
Keyword(s):  
Binding Site ◽  
Von Willebrand Factor ◽  
Platelet Adhesion ◽  
Binding Activity ◽  
Proteolytic Fragment ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Beta Galactosidase

Abstract The binding of von Willebrand factor (vWF) to platelet membrane glycoprotein Ib (GpIb) facilitates platelet adhesion to vascular subendothelium. In this study, we provide evidence that the vWF binding site is on glycocalicin (GC), a proteolytic fragment of GpIb, and we examine the role of the carbohydrate portion of GC on that binding. The binding to platelets of 6D1, a monoclonal antibody that recognizes an epitope on GpIb and blocks ristocetin-induced vWF binding to platelets, was inhibited by purified GC. In addition, purified GC inhibited ristocetin-dependent binding of 125I-labeled vWF to platelets. Since GC contains 60% carbohydrate by weight, we assessed the role of carbohydrate sequences on its interaction with antibody 6D1 and vWF. Based on the known sequence of the major oligosaccharide chain of GC--N- acetyl neuraminic acid, galactose, N-acetyl glucosamine, N-acetyl galactosamine--we treated GC sequentially with neuraminidase, beta- galactosidase, and beta-N-acetylglucosaminidase. Removal of sialic acid and galactose residues did not affect GC binding. Removal of N-acetyl glucosamine residues did not affect GC binding to 6D1 but did decrease the ability of GC to inhibit vWF binding to platelets, increasing the concentration needed to inhibit binding by 50% (IC50) 40-fold. This suggests that a portion of the oligosaccharide chains on GC contributes to the vWF binding activity of this molecule.

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