Your browser doesn't support javascript.
Show: 20 | 50 | 100
Results 1 - 3 de 3
Filter
1.
Blood ; 138(22): 2256-2268, 2021 12 02.
Article in English | MEDLINE | ID: covidwho-1443788

ABSTRACT

SARS-CoV-2 vaccine ChAdOx1 nCoV-19 (AstraZeneca) causes a thromboembolic complication termed vaccine-induced immune thrombotic thrombocytopenia (VITT). Using biophysical techniques, mouse models, and analysis of VITT patient samples, we identified determinants of this vaccine-induced adverse reaction. Super-resolution microscopy visualized vaccine components forming antigenic complexes with platelet factor 4 (PF4) on platelet surfaces to which anti-PF4 antibodies obtained from VITT patients bound. PF4/vaccine complex formation was charge-driven and increased by addition of DNA. Proteomics identified substantial amounts of virus production-derived T-REx HEK293 proteins in the ethylenediaminetetraacetic acid (EDTA)-containing vaccine. Injected vaccine increased vascular leakage in mice, leading to systemic dissemination of vaccine components known to stimulate immune responses. Together, PF4/vaccine complex formation and the vaccine-stimulated proinflammatory milieu trigger a pronounced B-cell response that results in the formation of high-avidity anti-PF4 antibodies in VITT patients. The resulting high-titer anti-PF4 antibodies potently activated platelets in the presence of PF4 or DNA and polyphosphate polyanions. Anti-PF4 VITT patient antibodies also stimulated neutrophils to release neutrophil extracellular traps (NETs) in a platelet PF4-dependent manner. Biomarkers of procoagulant NETs were elevated in VITT patient serum, and NETs were visualized in abundance by immunohistochemistry in cerebral vein thrombi obtained from VITT patients. Together, vaccine-induced PF4/adenovirus aggregates and proinflammatory reactions stimulate pathologic anti-PF4 antibody production that drives thrombosis in VITT. The data support a 2-step mechanism underlying VITT that resembles the pathogenesis of (autoimmune) heparin-induced thrombocytopenia.


Subject(s)
Antigen-Antibody Complex/immunology , Autoantibodies/immunology , COVID-19/prevention & control , Capsid Proteins/adverse effects , Drug Contamination , Genetic Vectors/adverse effects , HEK293 Cells/immunology , Immunoglobulin G/immunology , Platelet Factor 4/immunology , Purpura, Thrombocytopenic, Idiopathic/etiology , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/adverse effects , Adenoviridae/immunology , Animals , Antigen-Antibody Complex/ultrastructure , Autoantibodies/biosynthesis , Capillary Leak Syndrome/etiology , Capsid Proteins/immunology , Cell Line, Transformed , /immunology , Dynamic Light Scattering , Epitopes/chemistry , Epitopes/immunology , Extracellular Traps/immunology , Extravasation of Diagnostic and Therapeutic Materials/etiology , Genetic Vectors/immunology , HEK293 Cells/chemistry , Humans , Imaging, Three-Dimensional , Immunoglobulin G/biosynthesis , Inflammation , Mice , Microscopy/methods , Platelet Activation , Proteomics , Purpura, Thrombocytopenic, Idiopathic/blood , Purpura, Thrombocytopenic, Idiopathic/immunology , Sinus Thrombosis, Intracranial/diagnostic imaging , Sinus Thrombosis, Intracranial/immunology , Spike Glycoprotein, Coronavirus/immunology , Virus Cultivation
2.
Blood ; 137(26): 3656-3659, 2021 07 01.
Article in English | MEDLINE | ID: covidwho-1215090

ABSTRACT

Vaccination is crucial in combatting the severe acute respiratory syndrome coronavirus 2 pandemic. The rare complication of thrombocytopenia and thrombotic complications at unusual sites after ChAdOx1 nCov-19 vaccination is caused by platelet-activating antibodies directed against platelet factor 4 (PF4). We present a widely applicable whole-blood standard flow cytometric assay to identify the pathogenic antibodies associated with vaccine-induced immune-mediated thrombotic thrombocytopenia (VITT) after ChAdOx1 nCov-19 vaccination. This assay will enable rapid diagnosis by many laboratories. This trial was registered at www.clinicaltrials.gov as #NCT04370119.


Subject(s)
Autoantibodies/blood , COVID-19 Vaccines/adverse effects , COVID-19/prevention & control , Flow Cytometry/methods , Immunoglobulin G/blood , Platelet Activation/immunology , Platelet Factor 4/immunology , Purpura, Thrombocytopenic, Idiopathic/diagnosis , Receptors, IgG/immunology , SARS-CoV-2 , Vaccination/adverse effects , Antibody Specificity , Autoantibodies/biosynthesis , Autoantibodies/immunology , COVID-19 Vaccines/immunology , Heparin/adverse effects , Heparin/immunology , Humans , Immunoenzyme Techniques , Immunogenicity, Vaccine , Immunoglobulin G/biosynthesis , Immunoglobulin G/immunology , P-Selectin/analysis , Purpura, Thrombocytopenic, Idiopathic/etiology , Purpura, Thrombocytopenic, Idiopathic/immunology
3.
Blood Adv ; 4(24): 6315-6326, 2020 12 22.
Article in English | MEDLINE | ID: covidwho-985753

ABSTRACT

Community-acquired pneumonia by primary or superinfections with Streptococcus pneumoniae can lead to acute respiratory distress requiring mechanical ventilation. The pore-forming toxin pneumolysin alters the alveolar-capillary barrier and causes extravasation of protein-rich fluid into the interstitial pulmonary tissue, which impairs gas exchange. Platelets usually prevent endothelial leakage in inflamed pulmonary tissue by sealing inflammation-induced endothelial gaps. We not only confirm that S pneumoniae induces CD62P expression in platelets, but we also show that, in the presence of pneumolysin, CD62P expression is not associated with platelet activation. Pneumolysin induces pores in the platelet membrane, which allow anti-CD62P antibodies to stain the intracellular CD62P without platelet activation. Pneumolysin treatment also results in calcium efflux, increase in light transmission by platelet lysis (not aggregation), loss of platelet thrombus formation in the flow chamber, and loss of pore-sealing capacity of platelets in the Boyden chamber. Specific anti-pneumolysin monoclonal and polyclonal antibodies inhibit these effects of pneumolysin on platelets as do polyvalent human immunoglobulins. In a post hoc analysis of the prospective randomized phase 2 CIGMA trial, we show that administration of a polyvalent immunoglobulin preparation was associated with a nominally higher platelet count and nominally improved survival in patients with severe S pneumoniae-related community-acquired pneumonia. Although, due to the low number of patients, no definitive conclusion can be made, our findings provide a rationale for investigation of pharmacologic immunoglobulin preparations to target pneumolysin by polyvalent immunoglobulin preparations in severe community-acquired pneumococcal pneumonia, to counteract the risk of these patients becoming ventilation dependent. This trial was registered at www.clinicaltrials.gov as #NCT01420744.


Subject(s)
Platelet Activation , Streptolysins , Bacterial Proteins , Humans , Immunoglobulins , Prospective Studies
SELECTION OF CITATIONS
SEARCH DETAIL