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Ivanov DG, Ivetic N, Du Y, Nguyen SN, Le SH, Favre D, Nazy I, Kaltashov IA. Reverse Engineering of a Pathogenic Antibody Reveals the Molecular Mechanism of Vaccine-Induced Immune Thrombotic Thrombocytopenia. J Am Chem Soc 2023; 145:25203-25213. [PMID: 37949820 DOI: 10.1021/jacs.3c07846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2023]
Abstract
The massive COVID-19 vaccine roll-out campaign illuminated a range of rare side effects, the most dangerous of which─vaccine-induced immune thrombotic thrombocytopenia (VITT)─is caused by adenoviral (Ad)-vectored vaccines. VITT occurrence had been linked to the production of pathogenic antibodies that recognize an endogenous chemokine, platelet factor 4 (PF4). Mass spectrometry (MS)-based evaluation of the ensemble of anti-PF4 antibodies obtained from a VITT patient's blood indicates that the major component is a monoclonal antibody. Structural characterization of this antibody reveals several unusual characteristics, such as the presence of an N-glycan in the Fab segment and high density of acidic amino acid residues in the complementarity-determining regions. A recombinant version of this antibody (RVT1) was generated by transient expression in mammalian cells based on the newly determined sequence. It captures the key properties of VITT antibodies such as their ability to activate platelets in a PF4 concentration-dependent fashion. Homology modeling of the Fab segment reveals a well-defined polyanionic paratope, and the docking studies indicate that the polycationic segment of PF4 readily accommodates two Fab segments, cross-linking the antibodies to yield polymerized immune complexes. Their existence was verified with native MS by detecting assemblies as large as (RVT1)3(PF4)2, pointing out at FcγRIIa-mediated platelet activation as the molecular mechanism underlying VITT clinical manifestations. In addition to the high PF4 affinity, RVT1 readily binds other polycationic targets, indicating a polyreactive nature of this antibody. This surprising promiscuity not only sheds light on VITT etiology but also opens up a range of opportunities to manage this pathology.
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Affiliation(s)
- Daniil G Ivanov
- Department of Chemistry, University of Massachusetts-Amherst, Amherst, Massachusetts 01003, United States
| | - Nikola Ivetic
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON L8S 4K1, Canada
| | - Yi Du
- Department of Chemistry, University of Massachusetts-Amherst, Amherst, Massachusetts 01003, United States
| | - Son N Nguyen
- Department of Chemistry, University of Massachusetts-Amherst, Amherst, Massachusetts 01003, United States
| | - S Hung Le
- Department of Chemistry, University of Massachusetts-Amherst, Amherst, Massachusetts 01003, United States
| | - Daniel Favre
- Department of Chemistry, University of Massachusetts-Amherst, Amherst, Massachusetts 01003, United States
| | - Ishac Nazy
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON L8S 4K1, Canada
| | - Igor A Kaltashov
- Department of Chemistry, University of Massachusetts-Amherst, Amherst, Massachusetts 01003, United States
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Dabbiru VAS, Müller L, Schönborn L, Greinacher A. Vaccine-Induced Immune Thrombocytopenia and Thrombosis (VITT)-Insights from Clinical Cases, In Vitro Studies and Murine Models. J Clin Med 2023; 12:6126. [PMID: 37834770 PMCID: PMC10573542 DOI: 10.3390/jcm12196126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 09/15/2023] [Accepted: 09/20/2023] [Indexed: 10/15/2023] Open
Abstract
An effective worldwide vaccination campaign started and is still being carried out in the face of the coronavirus disease 2019 (COVID-19) pandemic. While vaccines are great tools to confront the pandemic, predominantly adenoviral vector-based vaccines can cause a rare severe adverse effect, termed vaccine-induced immune thrombocytopenia and thrombosis (VITT), in about 1 in 100,000 vaccinated individuals. VITT is diagnosed 5-30 days post-vaccination and clinically characterized by thrombocytopenia, strongly elevated D-dimer levels, platelet-activating anti-platelet factor 4 (PF4) antibodies and thrombosis, especially at atypical sites such as the cerebral venous sinus and/or splanchnic veins. There are striking similarities between heparin-induced thrombocytopenia (HIT) and VITT. Both are caused by anti-PF4 antibodies, causing platelet and leukocyte activation which results in massive thrombo-inflammation. However, it is still to be determined why PF4 becomes immunogenic in VITT and which constituent of the vaccine triggers the immune response. As VITT-like syndromes are increasingly reported in patients shortly after viral infections, direct virus-PF4 interactions might be most relevant. Here we summarize the current information and hypotheses on the pathogenesis of VITT and address in vivo models, especially murine models for further studies on VITT.
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Affiliation(s)
| | | | | | - Andreas Greinacher
- Institut für Transfusionsmedizin, Universitätsmedizin Greifswald, 17489 Greifswald, Germany; (V.A.S.D.); (L.M.); (L.S.)
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Sarkar A, Khandelwal S, Koma GT, Kim H, Gruel Y, Rollin J, Passam F, Wool GD, Arepally GM, Cines DB, Rauova L, Poncz M. Treatment of thrombocytopenia and thrombosis in HIT in mice using deglycosylated KKO: a novel therapeutic? Blood Adv 2023; 7:4112-4123. [PMID: 37196641 PMCID: PMC10388731 DOI: 10.1182/bloodadvances.2023009661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 05/09/2023] [Accepted: 05/10/2023] [Indexed: 05/19/2023] Open
Abstract
Heparin-induced thrombocytopenia (HIT) is characterized by thrombocytopenia associated with a highly prothrombotic state due to the development of pathogenic antibodies that recognize human platelet factor 4 (hPF4) complexed with various polyanions. Although nonheparin anticoagulants are the mainstay of care in HIT, subsequent bleeding may develop, and the risk of developing new thromboembolic events remain. We previously described a mouse immunoglobulin G2bκ (IgG2bκ) antibody KKO that mimics the sentinel features of pathogenic HIT antibodies, including binding to the same neoepitope on hPF4-polyanion complexes. KKO, like HIT IgGs, activates platelets through FcγRIIA and induces complement activation. We then questioned whether Fc-modified KKO could be used as a novel therapeutic to prevent or treat HIT. Using the endoglycosidase EndoS, we created deglycosylated KKO (DGKKO). Although DGKKO retained binding to PF4-polyanion complexes, it inhibited FcγRIIA-dependent activation of PF4-treated platelets triggered by unmodified KKO, 5B9 (another HIT-like monoclonal antibody), and IgGs isolated from patients with HIT. DGKKO also decreased complement activation and deposition of C3c on platelets. Unlike the anticoagulant fondaparinux, injection of DGKKO into HIT mice lacking mouse PF4, but transgenic for hPF4 and FcγRIIA, prevented and reversed thrombocytopenia when injected before or after unmodified KKO, 5B9, or HIT IgG. DGKKO also reversed antibody-induced thrombus growth in HIT mice. In contrast, DGKKO was ineffective in preventing thrombosis induced by IgG from patients with the HIT-related anti-PF4 prothrombotic disorder, vaccine-induced immune thrombotic thrombocytopenia. Thus, DGKKO may represent a new class of therapeutics for targeted treatment of patients with HIT.
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Affiliation(s)
- Amrita Sarkar
- Department of Pediatrics, The Children’s Hospital of Philadelphia, Philadelphia, PA
| | | | - Gavin T. Koma
- Department of Bioengineering, Temple University, Philadelphia, PA
| | - Hyunjun Kim
- Department of Pediatrics, The Children’s Hospital of Philadelphia, Philadelphia, PA
| | - Yves Gruel
- Department of Hemostasis, University Hospital Center of Tours, and EA4245 T2i, University of Tours, Tours, France
| | - Jerome Rollin
- Department of Hemostasis, University Hospital Center of Tours, and EA4245 T2i, University of Tours, Tours, France
| | - Freda Passam
- Central Clinical School, Faculty Medicine Health, University of Sydney, Sydney, Australia
| | | | | | - Douglas B. Cines
- Department of Pathology and Clinical Laboratories, The Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
| | - Lubica Rauova
- Department of Pediatrics, The Children’s Hospital of Philadelphia, Philadelphia, PA
- Department of Pediatrics, The Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
| | - Mortimer Poncz
- Department of Pediatrics, The Children’s Hospital of Philadelphia, Philadelphia, PA
- Department of Pediatrics, The Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
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Hirsch J, Uzun G, Zlamal J, Singh A, Bakchoul T. Platelet-neutrophil interaction in COVID-19 and vaccine-induced thrombotic thrombocytopenia. Front Immunol 2023; 14:1186000. [PMID: 37275917 PMCID: PMC10237318 DOI: 10.3389/fimmu.2023.1186000] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 05/04/2023] [Indexed: 06/07/2023] Open
Abstract
Coronavirus disease 2019 (COVID-19) is known to commonly induce a thrombotic diathesis, particularly in severely affected individuals. So far, this COVID-19-associated coagulopathy (CAC) has been partially explained by hyperactivated platelets as well as by the prothrombotic effects of neutrophil extracellular traps (NETs) released from neutrophils. However, precise insight into the bidirectional relationship between platelets and neutrophils in the pathophysiology of CAC still lags behind. Vaccine-induced thrombotic thrombocytopenia (VITT) is a rare autoimmune disorder caused by auto-antibody formation in response to immunization with adenoviral vector vaccines. VITT is associated with life-threatening thromboembolic events and thus, high fatality rates. Our concept of the thrombophilia observed in VITT is relatively new, hence a better understanding could help in the management of such patients with the potential to also prevent VITT. In this review we aim to summarize the current knowledge on platelet-neutrophil interplay in COVID-19 and VITT.
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Affiliation(s)
- Johannes Hirsch
- Institute of Clinical and Experimental Transfusion Medicine, University Hospital of Tuebingen, Tuebingen, Germany
- Center for Clinical Transfusion Medicine, University Hospital of Tuebingen, Tuebingen, Germany
| | - Günalp Uzun
- Institute of Clinical and Experimental Transfusion Medicine, University Hospital of Tuebingen, Tuebingen, Germany
- Center for Clinical Transfusion Medicine, University Hospital of Tuebingen, Tuebingen, Germany
| | - Jan Zlamal
- Institute of Clinical and Experimental Transfusion Medicine, University Hospital of Tuebingen, Tuebingen, Germany
- Center for Clinical Transfusion Medicine, University Hospital of Tuebingen, Tuebingen, Germany
| | - Anurag Singh
- Institute of Clinical and Experimental Transfusion Medicine, University Hospital of Tuebingen, Tuebingen, Germany
| | - Tamam Bakchoul
- Institute of Clinical and Experimental Transfusion Medicine, University Hospital of Tuebingen, Tuebingen, Germany
- Center for Clinical Transfusion Medicine, University Hospital of Tuebingen, Tuebingen, Germany
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Salih F, Schönborn L, Endres M, Greinacher A. Immunvermittelte Sinus- und Hirnvenenthrombosen: VITT und
prä-VITT als Modellerkrankung. AKTUEL RHEUMATOL 2022. [DOI: 10.1055/a-1936-3123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
ZusammenfassungIn diesem Übersichtsartikel beschreiben wir die klinischen und
paraklinischen Charakteristika der Vakzin-induzierten immunthrombotischen
Thrombozytopenie (VITT) und fassen den gegenwärtigen Kenntnisstand zur
Pathogenese zusammen. Bei der VITT bilden sich 5–20 Tage nach einer
Impfung mit einem Adenovirus-vektorbasiertem SARS-CoV-2-Vakzin (AstraZeneca oder
Johnson & Johnson) lebensbedrohliche Thrombosen aus, vor allem in den
zerebralen Sinus und Hirnvenen. Laborchemisch zeigt sich eine typische
Thrombozytopenie mit erhöhten D-Dimeren. Der Pathogenese liegen
immunologische Prozesse zugrunde, die Ähnlichkeiten mit der
Heparin-induzierten Thrombozytopenie aufweisen: so geht die VITT mit
hochtitrigem Immunoglobulin G gegen das thrombozytäre Protein
Plättchenfaktor 4 (PF4) einher. Durch die Interaktion mit dem Impfstoff
wird PF4 so verändert, dass es von Antikörper-produzierenden
Zellen des Immunsystems erkannt wird. Die so produzierten
Anti-PF4-Antikörper führen über thrombozytäre
FcγIIa-Rezeptoren zu einer Plättchenaktivierung. Der Nachweis
plättchenaktivierender Anti-PF4-Antikörper bestätigt die
Diagnose einer VITT. Antikoagulanzien, die die Bildung von Thrombin oder
Thrombin selbst blockieren und hochdosiertes i. v.-Immunglobulin G, das
die Fcγ-Rezeptor-vermittelte Zellaktivierung inhibiert, stellen die
wirksame und kausale Behandlung der VITT dar. Bei Patienten mit katastrophalem
Verlauf kann ein Plasmaaustausch versucht werden. Bei einigen Patienten ist ein
prä-VITT Syndrom als Prodromalstadium zu beoachten, das sich
typischerweise mit Kopfschmerzen manifestieren kann und dessen frühe
Behandlung hilft, thrombotische Komplikationen zu vermeiden. Die spezifische
Dynamik der VITT-assozierten Immunreaktion entspricht einer transienten,
sekundären Immunantwort. Aktuelle Studien gehen der Frage nach, wie PF4
an unterschiedliche adenovirale Proteine bindet und beleuchten die Rolle von
anderen Impfstoff-Bestandteilen als potentielle Liganden für die
PF4-Bindung. Einige dieser Faktoren sind auch an der Etablierung eines
proinflammatorischen Milieus („danger signal“) beteiligt, das
unmittelbar nach der Impfung die 1. Phase der VITT-Pathogenese triggert. Sobald
in der 2. Phase der VITT-Pathogenese hohe Titer von Anti-PF4-Antikörper
gebildet sind, aktivieren diese neben Thrombozyten auch Granulozyten. In einem
als NETose (von „neutrophil extracellular traps“) bezeichneten
Prozess setzen aktivierte Granulozyten dabei DNA frei, mit der PF4 weitere
Komplexe bildet, an die Anti-PF4-Antikörper binden. Dies
verstärkt die Fcγ-Rezeptor-vermittelte Zellaktivierung weiter
mit der Folge einer ausgeprägten Thrombin-Bildung. Zum Ende des Artikels
geben wir einen Ausblick, welchen Einfluss die bisherigen Erkenntnisse zur VITT
auf weitere globale Impfkampagnen gegen SARS-CoV-2 haben und beleuchten, wie
Anti-PF4-Antikörper jenseits von VITT und HIT auch eine Rolle bei
seltenen Erkrankungen spielen, die mit rezidivierenden venösen und
arteriellen Thrombosen einhergehen.
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Affiliation(s)
- Farid Salih
- Klinik für Neurologie mit Experimenteller Neurologie,
Charité Universitätsmedizin Berlin, Berlin,
Germany
| | - Linda Schönborn
- Institut für Transfusionsmedizin, Universitätsmedizin
Greifswald, Greifswald, Germany
| | - Matthias Endres
- Klinik für Neurologie mit Experimenteller Neurologie,
Charité Universitätsmedizin Berlin, Berlin,
Germany
| | - Andreas Greinacher
- Institut für Transfusionsmedizin, Universitätsmedizin
Greifswald, Greifswald, Germany
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