Your browser doesn't support javascript.
Show: 20 | 50 | 100
Results 1 - 3 de 3
Mol Ther Methods Clin Dev ; 23: 418-423, 2021 Dec 10.
Article in English | MEDLINE | ID: covidwho-1466817


Vaccination with the adenoviral-vector-based AstraZeneca ChAdOx1 nCov-19 (Vaxzevria) vaccine is efficient and safe. However, in rare cases vaccinated individuals developed life-threatening thrombotic complications, including thrombosis in cerebral sinus and splanchnic veins. Monitoring of the applied vector in vivo represents an important precondition to study the molecular mechanisms underlying vaccine-driven adverse effects now referred to as vaccine-induced immune thrombotic thrombocytopenia (VITT). We previously have shown that digital PCR (dPCR) is an excellent tool to quantify transgene copies in vivo. Here, we present a highly sensitive dPCR for in situ quantification of ChAdOx1 nCoV-19 copies. Using this method, we quantified vector copies in human plasma 24, 72, and 168 h post vaccination and in a variety of murine tissues in an experimental vaccination model 30 min post injection. We describe a method for high-sensitivity quantitative detection of ChAdOx1 nCoV-19 with possible implications to elucidate the mechanisms of severe ChAdOx1 nCov-19 vaccine complications.

Blood ; 138(22): 2256-2268, 2021 12 02.
Article in English | MEDLINE | ID: covidwho-1443788


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.

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
EBioMedicine ; 67: 103382, 2021 May.
Article in English | MEDLINE | ID: covidwho-1230443


BACKGROUND: Coagulopathy and inflammation are hallmarks of Coronavirus disease 2019 (COVID-19) and are associated with increased mortality. Clinical and experimental data have revealed a role for neutrophil extracellular traps (NETs) in COVID-19 disease. The mechanisms that drive thrombo-inflammation in COVID-19 are poorly understood. METHODS: We performed proteomic analysis and immunostaining of postmortem lung tissues from COVID-19 patients and patients with other lung pathologies. We further compared coagulation factor XII (FXII) and DNase activities in plasma samples from COVID-19 patients and healthy control donors and determined NET-induced FXII activation using a chromogenic substrate assay. FINDINGS: FXII expression and activity were increased in the lung parenchyma, within the pulmonary vasculature and in fibrin-rich alveolar spaces of postmortem lung tissues from COVID-19 patients. In agreement with this, plasmaaac acafajföeFXII activation (FXIIa) was increased in samples from COVID-19 patients. Furthermore, FXIIa colocalized with NETs in COVID-19 lung tissue indicating that NETs accumulation leads to FXII contact activation in COVID-19. We further showed that an accumulation of NETs is partially due to impaired NET clearance by extracellular DNases as DNase substitution improved NET dissolution and reduced FXII activation in vitro. INTERPRETATION: Collectively, our study supports that the NET/FXII axis contributes to the pathogenic chain of procoagulant and proinflammatory responses in COVID-19. Targeting both NETs and FXIIa may offer a potential novel therapeutic strategy. FUNDING: This study was supported by the European Union (840189), the Werner Otto Medical Foundation Hamburg (8/95) and the German Research Foundation (FR4239/1-1, A11/SFB877, B08/SFB841 and P06/KFO306).

COVID-19/metabolism , Extracellular Traps/metabolism , Factor XII/metabolism , Autopsy , Case-Control Studies , Deoxyribonucleases/blood , Deoxyribonucleases/metabolism , Humans , Lung/metabolism , Neutrophil Activation , Pneumonia , Proteomics