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. 2022 Jul 1;107(7):1687-1692.
doi: 10.3324/haematol.2021.280180.

Vaccine-induced immune thrombotic thrombocytopenia: a possible pathogenic role of ChAdOx1 nCoV-19 vaccine-encoded soluble SARS-CoV-2 spike protein

Manuela De Michele  1 , Paola Piscopo  2 , Alessio Crestini  2 , Roberto Rivabene  2 , Giulia D'Amati  3 , Martina Leopizzi  4 , Lucia Stefanini  5 , Fabio Pulcinelli  6 , Antonio Chistolini  7 , Marta Iacobucci  8 , Oscar G Schiavo  9 , Irene Berto  10 , Ettore Nicolini  9 , Luca Petraglia  9 , Maria Teresa Di Mascio  9 , Danilo Toni  10
Affiliations

Vaccine-induced immune thrombotic thrombocytopenia: a possible pathogenic role of ChAdOx1 nCoV-19 vaccine-encoded soluble SARS-CoV-2 spike protein

Manuela De Michele et al. Haematologica. .
No abstract available

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Figures

Figure 1.
Figure 1.
A thrombus from patient 1 with vaccine-induced immune thrombotic thrombocytopena was rich in platelets and stained positive for SARS-CoV-2 spike protein and ACE2. (A) Double immunofluorescence of thrombotic material retrieved from the right middle cerebral artery of patient 1 during the first mechanical thrombectomy. Staining with hematoxylin-eosin showed that the thrombus was made up almost exclusively of platelets, with abundant granulocytes. Platelets within the area encircled in (A) are stained in red with CD61 antibodies, the SARS-CoV-2 spike protein (SP) is stained in green, while the nuclei of the inflammatory cells are stained in blue with DAPI. The overlap of SARS-CoV-2 SP and platelets is shown in yellow (merge). (B) Immunohistochemistry highlights the presence of SARS-CoV-2 SP associated with decreased amounts of ACE2, within the thrombus of patient 1 (P1) as compared with a thrombus retrieved from a patient in the pre-pandemic era (CTL). H&E: hematoxylin-eosin; SARS-CoV-2: after severe acute respiratory virus coronavirus-2; ACE2: angiotensin-converting enzyme-2.
Figure 2.
Figure 2.
The SARS-CoV-2 spike protein contributes to ChAdOx1 nCoV-19 vaccine-induced platelet activation. (A, B) An antibody against the S1 domain of the SARS-CoV-2 spike protein (α-Spike) decreases vaccine-induced immune thrombotic thrombocytopenia (VITT) serum-induced platelet activation of washed platelets from healthy donors. Platelets were washed by serial centrifugation and resuspended in a solution of Tyrode’s buffer and sera (3:1) at a final concentration of 5x107 cells/mL. The blocking antibodies against the spike protein (SP) and FcγRIIA were incubated for 15 min at 4 mg/ml. Platelet activation was assessed by measuring (A) the binding of PAC1-FITC, an antibody that binds the active form integrin αIIbβ33, and (B) the binding of α-CD62P-PE, which is a marker of granule secretion, on a BD Accuri C6 Plus. The bar graph shows the mean ± standard deviation of the response of the platelets of the three patients (the response for each patient is the average of 3 technical replicates). In each experiment we always included negative controls with buffer alone and with sera from healthy donors who had been vaccinated with ChAdOx1 nCoV-19 but who did not experience any unusual side-effect after the injection. Statistical analyses were performed using ordinary one-way analysis of variance and the Hold-Sidak multiple comparison test. *P<0.05; **P<0.01, ***P<0.001, ****P<0.0001. (C) Working model of the mechanism of vaccine-induced platelet activation. We postulate a multiple-hit model for platelet activation in the etiopathogenesis of VITT The first hit is platelet activation by the SP. (a) The interaction between the SP and the ACE2 receptors on endothelial cells induces endothelial cell activation, (b) which results in platelet recruitment and activation through exposure of adhesion receptors and release of VWF. (c) The direct interaction between the SP and platelets would also activate platelets directly. (d) Activated platelets then release their granular contents which include large amounts of PF4 that, binding to polyanions, generate new antigens, which leads in some individuals to the production of anti-PF4/polyanion autoantibodies. (e) The second hit is the stimulation of platelets via the FcγRIIA by IgG/PF4 and IgG/PF4/polyanion immune-complexes. (f) IgG/PF4/polyanion immune-complexes also stimulate neutrophils that, (g) when co-stimulated by platelets, (h) release neutrophil extracellular traps (NET). (i) Thus, the third hit is NET, which support the coagulation cascade and further support platelet activation. These multiple stimuli amplify platelet activation and lead to thrombosis and/or thrombocytopenia. MFI: mean fluorescent intensity; HD: healthy donor.
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References

    1. Pavord S, Scully M, Hunt BJ, et al. . Clinical features of vaccine-induced immune thrombocytopenia and thrombosis. N Engl J Med. 2021;385(18):1680-1689. - PMC - PubMed
    1. Greinacher A, Thiele T, Warkentin TE, Weisser K, Kyrle PA, Eichinger S. Thrombotic thrombocytopenia after ChAdOx1 nCov-19 vaccination. N Engl J Med. 2021;384(22):2092-2101. - PMC - PubMed
    1. See I, Su JR, Lale A, et al. . US case reports of cerebral venous sinus thrombosis with thrombocytopenia after Ad26.COV2.S vaccination, March 2 to April 21, 2021. JAMA. 2021;325(24):2448-2456. - PMC - PubMed
    1. Greinacher A, Selleng K, Warkentin TE. Autoimmune heparin-induced thrombocytopenia. J Thromb Haemost. 2017;15(11):2099-2114. - PubMed
    1. Althaus K, Möller P, Uzun G, et al. . Antibody-mediated procoagulant platelets in SARS-CoV-2-vaccination associated immune thrombotic thrombocytopenia. Haematologica. 2021;106(8):2170-2179. - PMC - PubMed