Platelet Adhesion to Multimeric and Dimeric von Willebrand Factor and to Collagen Type III Preincubated With von Willebrand Factor

Wu, Yaping; Breugel, H. H. F. I. Van; Lankhof, H.; Wise, Robert J.; Handin, Robert I.; Groot, Philip G. de; Sixma, Jan J.

doi:10.1161/01.atv.16.5.611

Cited by 50 publications

(37 citation statements)

References 46 publications

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“…Additionally, the sheardependent morphology change of VWF described earlier was observed out of flow, about 5 minutes after the coverslip being dismounted from the shearing device. 6 However, larger VWF multimers are more active in promoting platelet adhesion, 9 and some unusually large molecules were present at the high shear regime, when perfusion was performed for 5 minutes. These molecules had also a fairly lobulated shape, which could be consistent with shear-induced morphologic changes.…”

Section: Discussionmentioning

confidence: 99%

Shear-dependent morphology of von Willebrand factor bound to immobilized collagen

Novák

Deckmyn

Damjanovich

et al. 2002

Blood

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We have developed an immunogold von Willebrand factor (VWF) detection method that permits almost complete coverage of individual VWF molecules, and by this unequivocal localization and morphologic analysis of collagen-bound VWF by atomic force microscopy (AFM). Perfusion of gel filtration-purified VWF in parallel plate perfusion chambers over glass coverslips coated with calf skin collagen, followed by AFM imaging in air, enabled us to assess possible morphologic differences between VWF bound at low (0.07 N/m 2 ‫؍‬ 0.7 dynes/ cm 2 ) and high (4.55 N/m 2 ‫؍‬ 45.5 dynes/ cm 2 ) shear stresses. No significant differences in VWF morphology were found, the molecules were oriented almost randomly, and there were no clear signs of VWF "uncoiling" either at a high or at a low shear regime. After perfusing 1 g/mL VWF for 5 minutes, surface coverage at high shear was almost twice the one seen at low shear, and some larger and more irregularly shaped VWF molecules could be seen at high shear. This difference disappeared, however, at 15 minutes of perfusion and was probably caused by diffusion kinetics. Moreover, the presence of 68 ؋ 10 9 /L washed fixed platelets in the perfusate did not have any visible effect on VWF morphology at high versus low shear stress. These findings suggest that shear stress does not influence significantly the overall molecular morphology of VWF during its binding to collagen-coated surface and are consistent with a constitutively expressed affinity of collagen-bound VWF for gly-

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Section: Discussionmentioning

confidence: 99%

Shear-dependent morphology of von Willebrand factor bound to immobilized collagen

Novák

Deckmyn

Damjanovich

et al. 2002

Blood

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“…To confirm the dependence on divalent cation in ␣ 2 -I domain/collagen interactions, we examined the extent of collagen binding in the presence of Mg 2ϩ , Ca 2ϩ , and EDTA. Since EDTA impaired the interaction of the anti-polyhistidine-HRP monoclonal antibody with the His tag motif, we expressed and purified metabolically labeled 35 S-␣ 2 -I protein. Consistent with previous reports, 35 S-␣ 2 -I protein binding to collagen type I was greatly reduced by the addition of 2 mM EDTA (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Labeled ␣ 2 -I protein was purified as described above. The specific activity of the purified 35 S-␣ 2 -I protein was determined to 2.4 ϫ 10 4 cpm/g. Collagen Binding Assay-A final concentration of either 500 or 10 g/ml collagen or a 1% solution of bovine serum albumin (BSA) was added to microtiter wells in 65 mM sodium phosphate buffer, pH 7.2, for 90 min at 37°C.…”

Section: Methodsmentioning

confidence: 99%

“…Collagen-binding assays in the presence of EDTA or divalent cations were carried out with 35 S-labeled ␣ 2 -I protein (500 nM) and EDTA, MgCl 2 , or CaCl 2 (2 mM). After a 60-min incubation, the wells were washed and separated for scintillation counting.…”

Section: Methodsmentioning

confidence: 99%

“…After a 60-min incubation, the wells were washed and separated for scintillation counting. For the antibodyblocking assay, 35 S-labeled ␣ 2 -I protein (500 nM) was preincubated with anti-human ␣ 2 antibodies 6F1 or 12F1 (1.5 M) for 30 min and added to the wells. After 60 min, the wells were washed and removed for scintillation counting.…”

Section: Methodsmentioning

confidence: 99%

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Functional Analysis of a Recombinant Glycoprotein Ia/IIa (Integrin α2β1) I Domain That Inhibits Platelet Adhesion to Collagen and Endothelial Matrix under Flow Conditions

Estavillo

Ritchie

Diacovo³

et al. 1999

Journal of Biological Chemistry

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The interaction of platelets with collagen plays an important role in primary hemostasis. Glycoprotein Ia/ IIa (GPIa/IIa, integrin ␣ 2 ␤ 1 ) is a major platelet receptor for collagen. The binding site for collagen has been mapped to the I domain within the ␣ 2 subunit (GPIa). In order to assess the role of the ␣ 2 -I domain structure in GPIa/IIa binding to collagen, a recombinant I domain (amino acids 126 -337) was expressed in Escherichia coli. The ␣ 2 -I protein bound human types I and III collagen in a saturable and divalent cation-dependent manner and was blocked by the ␣ 2 ␤ 1 function blocking antibody 6F1. The ␣ 2 -I protein inhibited collagen-induced platelet aggregation (IC 50 ‫؍‬ 600 nM). Unexpectedly, 6F1, an antibody that fails to inhibit platelet aggregation in plateletrich plasma, blocked the inhibitory effect of the ␣ 2 -I protein. The ␣ 2 -I protein was able to prevent platelet adhesion to a collagen surface exposed to flowing blood under low shear stress. Interestingly, it inhibited platelet adhesion to extracellular matrix at high shear stress. These results, taken together, provide firm evidence that GPIa/IIa directly mediates the first contact of platelets with collagen under both stirring and flow conditions. Platelet adhesion to subendothelium at sites of vascular injury is a critical initial step in hemostasis. Platelets adhere to collagen by two mechanisms: directly by the interaction of platelet membrane proteins with collagen and indirectly via bridging molecules such as von Willebrand factor (vWF) 1 that bind to both platelet glycoprotein (GP) Ib␣ and collagen. This latter interaction is necessary to confer resistance to detachment under high flow and shear conditions. It also stabilizes platelet adhesion via the collagen receptor (1).GPIa/IIa (integrin ␣ 2 ␤ 1 , VLA2, CD49b/29) is member of the integrin family of heterodimeric molecules that mediate both cell-cell adhesion and adhesion between cells and the extracellular matrix (ECM) (2). The integrin ␣ 2 ␤ 1 is found on several different cell types, and its function may vary depending on the particular cell on which it is expressed. While it is a collagen receptor in platelets and fibroblastic cells, it functions as both a collagen and a laminin receptor on endothelial and epithelial cells (3, 4). It also acts as receptor for the human pathogen echovirus-1 (5) and is involved in the migration of tumor cells within collagenous matrices (6). Integrin ␣ 2 ␤ 1 is a major collagen receptor in platelets (7). Although ␣ 2 ␤ 1 -mediated adhesion appears to be an essential primary step in collagen-platelet interactions, it is still not known whether collagen-␣ 2 ␤ 1 binding alone is sufficient to support platelet adhesion and to induce collagen-dependent platelet activation (8 -10). Platelets from patients described as having mild bleeding disorders due to deficient expression of either the ␣ 2 -integrin (11-14) or GPVI (15) have demonstrated impaired aggregation in vitro in response to collagen. Antibodies against the collagen receptor GPI...

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Pulmonary platelet thrombi and vascular pathology in acute chest syndrome in patients with sickle cell disease

et al. 2016

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A growing body of evidence suggests a role for platelets in sickle cell disease (SCD). Despite the pro-inflammatory, occlusive nature of platelets, a role for platelets in acute chest syndrome (ACS), however, remains understudied. To provide evidence and potentially describe contributory factors for a putative link between ACS and platelets, we performed an autopsy study of 20 SCD cases – 10 of whom died from ACS and 10 whose deaths were not ACS-related. Pulmonary histopathology and case history were collected. We discovered that disseminated pulmonary platelet thrombi were present in 3 out of 10 of cases with ACS, but none of the matched cases without ACS. Those cases with detected thrombi were associated with significant deposition of endothelial vWF and detection of large vWF aggregates adhered to endothelium. Potential clinical risk factors were younger age and higher platelet count at presentation. However, we also noted a sharp and significant decline in platelet count prior to death in each case with platelet thrombi in the lungs. In this study, neither hydroxyurea use nor perimortem transfusion was associated with platelet thrombi. Surprisingly, in all cases, there was profound pulmonary artery remodeling with both thrombotic and proliferative pulmonary plexiform lesions. The severity of remodeling was not associated with a severe history of ACS, or hydroxyurea use, but was inversely correlated with age. We thus provide evidence of undocumented presence of platelet thrombi in cases of fatal ACS describe clinical correlates. We also provide novel correlates of pulmonary remodeling in SCD.

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Platelet Adhesion to Multimeric and Dimeric von Willebrand Factor and to Collagen Type III Preincubated With von Willebrand Factor

Cited by 50 publications

References 46 publications

Shear-dependent morphology of von Willebrand factor bound to immobilized collagen

Shear-dependent morphology of von Willebrand factor bound to immobilized collagen

Functional Analysis of a Recombinant Glycoprotein Ia/IIa (Integrin α2β1) I Domain That Inhibits Platelet Adhesion to Collagen and Endothelial Matrix under Flow Conditions

Pulmonary platelet thrombi and vascular pathology in acute chest syndrome in patients with sickle cell disease

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