scholarly journals Recognition of PF4-VWF complexes by heparin-induced thrombocytopenia antibodies contributes to thrombus propagation

Blood ◽  
2020 ◽  
Vol 135 (15) ◽  
pp. 1270-1280 ◽  
Author(s):  
Ian Johnston ◽  
Amrita Sarkar ◽  
Vincent Hayes ◽  
Gavin T. Koma ◽  
Gowthami M. Arepally ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Complex Formation ◽  
Platelet Adhesion ◽  
Thrombus Formation ◽  
Microfluidic System ◽  
Microfluidic Channels ◽  
Platelet Factor ◽  
Heparin Induced Thrombocytopenia ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract Heparin-induced thrombocytopenia (HIT) is a prothrombotic disorder mediated by complexes between platelet factor 4 (PF4) and heparin or other polyanions, but the risk of thrombosis extends beyond exposure to heparin implicating other PF4 partners. We recently reported that peri-thrombus endothelium is targeted by HIT antibodies, but the binding site(s) has not been identified. We now show that PF4 binds at multiple discrete sites along the surface of extended strings of von Willebrand factor (VWF) released from the endothelium following photochemical injury in an endothelialized microfluidic system under flow. The HIT-like monoclonal antibody KKO and HIT patient antibodies recognize PF4-VWF complexes, promoting platelet adhesion and enlargement of thrombi within the microfluidic channels. Platelet adhesion to the PF4-VWF-HIT antibody complexes is inhibited by antibodies that block FcγRIIA or the glycoprotein Ib-IX complex on platelets. Disruption of PF4-VWF-HIT antibody complexes by drugs that prevent or block VWF oligomerization attenuate thrombus formation in a murine model of HIT. Together, these studies demonstrate assembly of HIT immune complexes along VWF strings released by injured endothelium that might propagate the risk of thrombosis in HIT. Disruption of PF4-VWF complex formation may provide a new therapeutic approach to HIT.

scholarly journals Cleavage of anti-PF4/heparin IgG by a bacterial protease and potential benefit in heparin-induced thrombocytopenia

Blood ◽  
2019 ◽  
Vol 133 (22) ◽  
pp. 2427-2435 ◽  
Author(s):  
Claire Kizlik-Masson ◽  
Quentin Deveuve ◽  
Yuhang Zhou ◽  
Caroline Vayne ◽  
Gilles Thibault ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Whole Blood ◽  
Messenger Rna ◽  
Microfluidic Channels ◽  
Platelet Factor ◽  
Cellular Activation ◽  
Heparin Induced Thrombocytopenia ◽  
Bacterial Protease ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract Heparin-induced thrombocytopenia (HIT) is due to immunoglobulin G (IgG) antibodies, which bind platelet factor 4 (PF4) modified by polyanions, such as heparin (H). IgG/PF4/polyanion complexes directly activate platelets via Fc gamma type 2 receptor A (FcγRIIA) receptors. A bacterial protease, IgG-degrading enzyme of Streptococcus pyogenes (IdeS), cleaves the hinge region of heavy-chain IgG, abolishing its ability to bind FcγR, including FcγRIIA. We evaluated whether cleavage of anti-PF4/H IgG by IdeS could suppress the pathogenicity of HIT antibodies. IdeS quickly cleaved purified 5B9, a monoclonal chimeric anti-PF4/H IgG1, which led to the formation of single cleaved 5B9 (sc5B9), without any reduction in binding ability to the PF4/H complex. However, as compared with uncleaved 5B9, the affinity of sc5B9 for platelet FcγRIIA was greatly reduced, and sc5B9 was also unable to induce heparin-dependent platelet activation. In addition, incubating IdeS in whole blood containing 5B9 or HIT plasma samples led to cleavage of anti-PF4/H antibodies, which fully abolished the ability to induce heparin-dependent platelet aggregation and tissue factor messenger RNA synthesis by monocytes. Also, when whole blood was perfused in von Willebrand factor–coated microfluidic channels, platelet aggregation and fibrin formation induced by 5B9 with heparin was strongly reduced after IdeS treatment. Finally, IdeS prevented thrombocytopenia and hypercoagulability induced by 5B9 with heparin in transgenic mice expressing human PF4 and FcγRIIA receptors. In conclusion, cleavage of anti-PF4/H IgG by IdeS abolishes heparin-dependent cellular activation induced by HIT antibodies. IdeS injection could be a potential treatment of patients with severe HIT.

Signaling through GP Ib-IX-V activates αIIbβ3 independently of other receptors

Blood ◽  
2004 ◽  
Vol 103 (9) ◽  
pp. 3403-3411 ◽  
Author(s):  
Ana Kasirer-Friede ◽  
Maria Rita Cozzi ◽  
Mario Mazzucato ◽  
Luigi De Marco ◽  
Zaverio M. Ruggeri ◽  
...  
Keyword(s):  
Tyrosine Phosphorylation ◽  
Platelet Adhesion ◽  
Thrombus Formation ◽  
Signaling Proteins ◽  
Phosphatidylinositol 3 Kinase ◽  
Kinase C ◽  
A1 Domain ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Pharmacologic Inhibition

Abstract Platelet adhesion to von Willebrand factor (VWF) activates αIIbβ3, a prerequisite for thrombus formation. However, it is unclear whether the primary VWF receptor, glycoprotein (GP) Ib-IX-V, mediates αIIbβ3 activation directly or through other signaling proteins physically associated with it (eg, FcR γ-chain), possibly with the contribution of other agonist receptors and of VWF signaling through αIIbβ3. To resolve this question, human and GP Ibα transgenic mouse platelets were plated on dimeric VWF A1 domain (dA1VWF), which engages only GP Ib-IX-V, in the presence of inhibitors of other agonist receptors. Platelet adhesion to dA1VWF induced Src kinase-dependent tyrosine phosphorylation of the FcR γ-chain and the adapter molecule, ADAP, and triggered intracellular Ca2+ oscillations and αIIbβ3 activation. Inhibition of Ca2+ oscillations with BAPTA-AM prevented αIIbβ3 activation but not tyrosine phosphorylation. Pharmacologic inhibition of protein kinase C (PKC) or phosphatidylinositol 3-kinase (PI 3-kinase) prevented αIIbβ3 activation but not Ca2+ oscillations. Inhibition of Src with 2 distinct compounds blocked all responses downstream of GP Ib-IX-V under static or flow conditions. However, dA1VWF-induced responses were reduced only slightly in GP Ibα transgenic platelets lacking FcR γ-chain. These data establish that GP Ib-IX-V itself can signal to activate αIIbβ3, through sequential actions of Src kinases, Ca2+ oscillations, and PI 3-kinase/PKC. (Blood. 2004;103:3403-3411)

Levels of von Willebrand factor and ADAMTS13 determine clinical outcome after cardioversion for atrial fibrillation

2011 ◽  
Vol 105 (03) ◽  
pp. 435-443 ◽  
Author(s):  
Veronika Bruno ◽  
Rudolf Jarai ◽  
Susanne Gruber ◽  
Thomas Höchtl ◽  
Ivan Brozovic ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Von Willebrand Factor ◽  
Platelet Adhesion ◽  
Independent Predictor ◽  
Thrombus Formation ◽  
Critical Role ◽  
Inverse Correlation ◽  
Von Willebrand ◽  
Rhythm Stability ◽  
Willebrand Factor

SummaryVon Willebrand factor (vWF) plays an essential role in platelet adhesion and thrombus formation. Patients with atrial fibrillation (AF) exhibit higher plasma vWF and lower ADAMTS13 antigen levels compared to controls. Little is known about vWF and ADAMTS13 in AF patients treated with cardioversion (CV). Thus we investigated the alterations of plasma vWF and ADAMTS13 after CV and evaluated the predictive value of these parameters for recurrence of AF. In this observational study we determined plasma levels of vWF and ADAMTS13 in 77 patients before and immediately after CV, as well as 24 hours (h) and six weeks thereafter, by means of commercially available assays. The vWF/ ADAMTS13-ratio was significantly elevated immediately after CV (p=0.02) and 24 h after CV (p=0.002) as compared to baseline levels. ADAMTS13, 24 h after CV, exhibited a significant association with recurrence of AF (HR: 0.97; p=0.037). Accordingly, tertiles of ADAMTS13 showed a stepwise inverse correlation with the risk of recurrent AF (HR: 0.50; p=0.009). After adjustment for confounders, ADAMTS13 remained significant as an independent predictor of recurrent AF (HR: 0.61; p=0.047). Similarly, the vWF/ADAMTS13-ratio, 24 h after CV, was associated with rhythm stability and remained an independent predictor of recurrent AF (HR: 1.88; p=0.028). The regulation of vWF and its cleaving protease ADAMTS13 after CV might play a critical role in producing a pro-thrombotic milieu immediately after CV for AF. Since ADAMTS13 plasma concentration and the vWF/ADAMTS13-ratio are independently associated with rhythm stability, these indexes might be used for prediction of recurrence of AF.

Simulation of platelet adhesion and aggregation regulated by fibrinogen and von Willebrand factor

2008 ◽  
Vol 99 (01) ◽  
pp. 108-115 ◽  
Author(s):  
Koichiro Yano ◽  
Ken-ichi Tsubota ◽  
Takuji Ishikawa ◽  
Shigeo Wada ◽  
Takami Yamaguchi ◽  
...  
Keyword(s):  
Platelet Adhesion ◽  
Thrombus Formation ◽  
Simple Shear Flow ◽  
Stokesian Dynamics ◽  
General Observation ◽  
Significant Development ◽  
Platelet Adhesion And Aggregation ◽  
Von Willebrand ◽  
Willebrand Factor

SummaryWe propose a method to analyze platelet adhesion and aggregation computationally, taking into account the distinct properties of two plasma proteins, vonWillebrand factor (vWF) and fibrinogen (Fbg). In this method, the hydrodynamic interactions between platelet particles under simple shear flow were simulated using Stokesian dynamics based on the additivity of velocities. The binding force between particles mediated by vWF and Fbg was modeled using the Voigt model. Two Voigt models with different properties were introduced to consider the distinct behaviors of vWF and Fbg. Our results qualitatively agreed with the general observation of a previous in-vitro experiment, thus demonstrating that the significant development of thrombus formation in height requires not only vWF, but also Fbg. This agreement of simulation and experimental results qualitatively validates our model and suggests that consideration of the distinct roles of vWF and Fbg is essential to investigate the physiological and pathophysiological mechanisms of thrombus formation using a computational approach.

PRIMARY BINDING SITE OF VON WILLEBRAND FACTOR IN THE SUBENDOTHELIUM WHICH MEDIATES PLATELET ADHESION IS NOT COLLAGEN

1987 ◽  
Author(s):  
Philip G de Groot ◽  
Jan A van Mourik ◽  
Jan J Sixma
Keyword(s):  
Monoclonal Antibody ◽  
Von Willebrand Factor ◽  
Platelet Adhesion ◽  
Collagen Type ◽  
Collagen Type I ◽  
Extracellular Matrices ◽  
Type I ◽  
Type Iii ◽  
Von Willebrand ◽  
Willebrand Factor

We have studies the binding of von Willebrand factor (vWF) to extracellular matrices of endothelial cells and smooth muscle cells and to the vessel wall of human umbilical arteries in relation to its function in supporting platelet adhesion at high shear rates. CLB-RAg 38, a monoclonal antibody directed against vWF inhibits the binding of 125I-vWF extracellular matrices completely. The binding of 125I-vWF to subendothelium is not inhibited, because there are many different binding sites. CLB-RAg 38 inhibits platelet adhesion to extracellular matrices and subendothelium, in sofar as it is dependent on plasma vWF. CLB-RAg 38 has no effect on adhesion depending on vWF already bound to the matrix or subendothelium. CLB-RAg 38 does not inhibit binding of vWF to collagen type I and type III. Another monoclonal antibody against vWF, CLB-RAg 201, completely inhibits binding of vWF to collagen type I and type III. CLB-RAg 201 does not inhibit binding of 125I-vWF ot the extracellular matrices. CLB-RAg 201 partly inhibits platelet adhesion but this inhibition is also present when the adhesion depends on vWF already present in matrix or subendothelium, indicating that CLB-RAg 201 also inhibits the adhesion of platelets directly, this in contrast to CLB-RAg 38. The epitopes for CLB-RAg 201 and 38 were found on different tryptic fragments of vWF. These data indicate that vWF binds to subendothelium and to matrices of cultured cells by mechanism that is different from binding to collagen.

Endothelial CD40 Mediates Microvascular von Willebrand Factor-Dependent Platelet Adhesion Inducing Inflammatory Venothrombosis in ADAMTS13 Knockout Mice

2020 ◽  
Vol 120 (03) ◽  
pp. 466-476
Author(s):  
Sibgha Tahir ◽  
Andreas H. Wagner ◽  
Steffen Dietzel ◽  
Hanna Mannell ◽  
Joachim Pircher ◽  
...  
Keyword(s):  
Von Willebrand Factor ◽  
Knockout Mice ◽  
Platelet Adhesion ◽  
Thrombus Formation ◽  
Cd40 Ligand ◽  
Inflammatory Conditions ◽  
String Formation ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract Background von Willebrand factor (vWF) plays an important role in platelet activation. CD40–CD40 ligand (CD40L) induced vWF release has been described in large vessels and cultured endothelium, but its role in the microcirculation is not known. Here, we studied whether CD40 is expressed in murine microvessels in vivo, whether CD40L induces platelet adhesion and leukocyte activation, and how deficiency of the vWF cleaving enzyme ADAMTS13 affects these processes. Methods and Results The role of CD40L in the formation of beaded platelet strings reflecting their adhesion to ultralarge vWF fibers (ULVWF) was analyzed in the murine cremaster microcirculation in vivo. Expression of CD40 and vWF was studied by immunohistochemistry in isolated and fixed cremasters. Microvascular CD40 was only expressed under inflammatory conditions and exclusively in venous endothelium. We demonstrate that CD40L treatment augmented the number of platelet strings, reflecting ULVWF multimer formation exclusively in venules and small veins. In ADAMTS13 knockout mice, the number of platelet strings further increased to a significant extent. As a consequence extensive thrombus formation was induced in venules of ADAMTS13 knockout mice. In addition, circulating leukocytes showed primary and rapid adherence to these platelet strings followed by preferential extravasation in these areas. Conclusion CD40L is an important stimulus of microvascular endothelial ULVWF release, subsequent platelet string formation and leukocyte extravasation but only in venous vessels under inflammatory conditions. Here, the lack of ADAMTS13 leads to severe thrombus formation. The results identify CD40 expression and ADAMTS13 activity as important targets to prevent microvascular inflammatory thrombosis.

Antibody-mediated thrombosis: Relation to the antiphospholipid syndrome

Lupus ◽  
1998 ◽  
Vol 7 (2_suppl) ◽  
pp. 63-66 ◽  
Author(s):  
J Vermylen ◽  
C Van Geet ◽  
J Arnout
Keyword(s):  
Monoclonal Antibody ◽  
Antiphospholipid Syndrome ◽  
Von Willebrand Factor ◽  
Complement Activation ◽  
Protein S ◽  
General Category ◽  
Heparin Induced Thrombocytopenia ◽  
Xenograft Rejection ◽  
Von Willebrand ◽  
Willebrand Factor

Various forms of antibody-mediated thrombosis are presented and the mechanisms involved in their pathogenesis are discussed. Antibody-mediated thrombosis includes heparin-induced thrombocytopenia and thrombosis, autoantibodies to von Willebrand factor mimicking an antiphospholipid syndrome, thrombosis following injection of the murine monoclonal antibody OKT3, hyperacute and acute xenograft rejection, and varicella-associated antibody against protein S. In several of these entities the pathogenesis of thrombosis is closely related to development of cellular procoagulant activity through tight occupancy of Fc receptors, or through complement activation, or through cell-cell interactions. Integrating the antiphospholipid syndrome into the more general category of antibody-mediated thrombosis may provide some hints as to how we could approach the study of those intriguing patients who have the clinical features of the antiphospholipid syndrome but lack those antibodies that currently characterize it.

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

Glycoprotein Ibα and von Willebrand factor in primary platelet adhesion and thrombus formation: Lessons from mutant mice

2008 ◽  
Vol 99 (02) ◽  
pp. 264-270 ◽  
Author(s):  
Anil K. Chauhan ◽  
Denisa D. Wagner ◽  
Wolfgang Bergmeier
Keyword(s):  
Von Willebrand Factor ◽  
Platelet Adhesion ◽  
Thrombus Formation ◽  
Mutant Mice ◽  
Receptor Complex ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Primary Platelet ◽  
Adhesion Process ◽  
Main Ligand

SummaryThe von Willebrand factor (VWF) receptor complex, glycoprotein (GP)Ib-V-IX, and its main ligand VWF play a key role in the adhesion process of platelets to sites of vascular injury. Recent studies in mutant mice have shed new light on the importance of either molecule for the development of arterial and venous thrombosis. In this review, we summarize the most important aspects from these studies.

scholarly journals Systemic antithrombotic effects of ADAMTS13

2006 ◽  
Vol 203 (3) ◽  
pp. 767-776 ◽  
Author(s):  
Anil K. Chauhan ◽  
David G. Motto ◽  
Colin B. Lamb ◽  
Wolfgang Bergmeier ◽  
Michael Dockal ◽  
...  
Keyword(s):  
Platelet Adhesion ◽  
Thrombus Formation ◽  
Type I ◽  
Inhibitory Antibody ◽  
Antithrombotic Agent ◽  
Antithrombotic Effects ◽  
Life Threatening ◽  
Adamts13 Deficiency ◽  
Von Willebrand ◽  
Willebrand Factor

The metalloprotease ADAMTS13 (a disintegrin-like and metalloprotease with thrombospondin type I repeats 13) cleaves highly adhesive large von Willebrand factor (VWF) multimers after their release from the endothelium. ADAMTS13 deficiency is linked to a life-threatening disorder, thrombotic thrombocytopenic purpura (TTP), characterized by platelet-rich thrombi in the microvasculature. Here, we show spontaneous thrombus formation in activated microvenules of Adamts13−/− mice by intravital microscopy. Strikingly, we found that ADAMTS13 down-regulates both platelet adhesion to exposed subendothelium and thrombus formation in injured arterioles. An inhibitory antibody to ADAMTS13 infused in wild-type mice prolonged adhesion of platelets to endothelium and induced thrombi formation with embolization in the activated microvenules. Absence of ADAMTS13 did not promote thrombi formation in αIIbβ3 integrin-inhibited blood. Recombinant ADAMTS13 reduced platelet adhesion and aggregation in histamine-activated venules and promoted thrombus dissolution in injured arterioles. Our findings reveal that ADAMTS13 has a powerful natural antithrombotic activity and recombinant ADAMTS13 could be used as an antithrombotic agent.

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