Platelets can contain SARS-CoV-2 RNA and are hyperactivated in COVID-19 (original) (raw)
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Platelet Function in Viral Immunity and SARS-CoV-2 Infection
Seminars in Thrombosis and Hemostasis
Platelets, as nonnucleated blood components, are classically recognized for their pivotal role in hemostasis. In recent years, however, accumulating evidence points to a nonhemostatic role for platelets, as active participants in the inflammatory and immune responses to microbial organisms in infectious diseases. This stems from the ability of activated platelets to secrete a plethora of immunomodulatory cytokines and chemokines, as well as directly interplaying with viral receptors. While much attention has been given to the role of the cytokine storm in the severity of the coronavirus disease 2019 (COVID-19), less is known about the contribution of platelets to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Here, we give a brief overview on the platelet contribution to antiviral immunity and response during SARS-CoV-2 infection.
SSRN Electronic Journal, 2020
Coronavirus disease-2019 (COVID-19) caused by SARS-CoV-2 is an ongoing viral pandemic marked by increased risk of thrombotic events. However, the role of platelets in the elevated observed thrombotic risk in COVID-19 and utility of anti-platelet agents in attenuating thrombosis is unknown. We aimed to determine if human platelets express the known SARS-CoV-2 receptor-protease axis on their cell surface and assess whether the anti-platelet effect of aspirin may mitigate risk of myocardial infarction (MI), cerebrovascular accident (CVA), and venous thromboembolism (VTE) in COVID-19. Expression of ACE2 and TMPRSS2 on human platelets were detected by immunoblotting and confirmed by confocal microscopy. We evaluated 22,072 symptomatic patients tested for COVID-19. Propensity-matched analyses were performed to determine if treatment with aspirin or non-steroidal anti-inflammatory drugs (NSAIDs) affected thrombotic outcomes in COVID-19. Neither aspirin nor NSAIDs affected mortality in COVID-19. However, both aspirin and NSAID therapies were associated with increased risk of the combined thrombotic endpoint of (MI), (CVA), and (VTE). Thus, while platelets clearly express ACE2-TMPRSS2 receptor-protease axis for SARS-CoV-2 infection, aspirin does not prevent thrombosis and death in COVID-19. The mechanisms of thrombosis in COVID-19, therefore, appears distinct and the role of platelets as direct mediators of SARS-CoV-2-mediated thrombosis warrants further investigation.
Platelet Count in Patients with SARS-CoV-2 Infection: A Prognostic Factor in COVID-19
Journal of Clinical Medicine
COVID-19 patients may manifest thrombocytopenia and some of these patients succumb to infection due to coagulopathy. The aim of our study was to examine platelet count values in patients infected with SARS-CoV-2, comparing them to a control group consisting of non-COVID-19 patients. Moreover, we evaluated the correlation between the platelet value and the respiratory alteration parameters and the outcome (hospitalization and mortality) in COVID-19 patients. The mean platelet values (×109/L) differed between patients with positive or negative SARS-CoV-2 swabs (242.1 ± 92.1 in SARS-CoV-2 negative vs. 215.2 ± 82.8 in COVID-19 patients, p < 0.001). In COVID-19 patients, the platelet count correlated with the A-aO2 gradient (p = 0.001, rho = −0.149), with its increase over the expected (p = 0.013; rho = −0.115), with the PaO2 values (p = 0.036; rho = 0.093), with the PCO2 values (p = 0.003; rho = 0.134) and with the pH values (p = 0.016; rho = −0.108). In COVID-19 negative patients, t...
2021
IntroductionCoagulation dysfunction and thromboembolism emerge as strong comorbidity factors in severe COVID-19. However, it is unclear when particularly platelet activation markers and coagulation factors dysregulated during the pathogenesis of COVID-19. Here, we sought to assess the levels of coagulation and platelet activation markers at moderate and severe stages of COVID-19 to understand the pathogenesis.MethodsTo understand this, hospitalized COVID-19 patients with (severe cases that required intensive care) or without pneumonia (moderate cases) were recruited. Phenotypic and molecular characterizations were performed employing basic coagulation tests including PT, APTT, D-Dimer and TFPI. The flow cytometry-based multiplex assays were performed to assess FXI, anti-thrombin, prothrombin, fibrinogen, FXIII, P-selectin, sCD40L, plasminogen, tissue-plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1) and D-Dimer.ResultsThe investigations revealed induction of pla...
Infection of lung megakaryocytes and platelets by SARS-CoV-2 anticipate fatal COVID-19
Cellular and Molecular Life Sciences
SARS-CoV-2, although not being a circulatory virus, spread from the respiratory tract resulting in multiorgan failures and thrombotic complications, the hallmarks of fatal COVID-19. A convergent contributor could be platelets that beyond hemostatic functions can carry infectious viruses. Here, we profiled 52 patients with severe COVID-19 and demonstrated that circulating platelets of 19 out 20 non-survivor patients contain SARS-CoV-2 in robust correlation with fatal outcome. Platelets containing SARS-CoV-2 might originate from bone marrow and lung megakaryocytes (MKs), the platelet precursors, which were found infected by SARS-CoV-2 in COVID-19 autopsies. Accordingly, MKs undergoing shortened differentiation and expressing anti-viral IFITM1 and IFITM3 RNA as a sign of viral sensing were enriched in the circulation of deadly COVID-19. Infected MKs reach the lung concomitant with a specific MK-related cytokine storm rich in VEGF, PDGF and inflammatory molecules, anticipating fatal out...
Frontiers in Immunology, 2022
BackgroundHemostasis and inflammation are both dysregulated in patients with moderate-to-severe coronavirus disease 2019 (COVID-19). Yet, both processes can also be disturbed in patients with other respiratory diseases, and the interactions between coagulation, inflammation, and disease severity specific to COVID-19 are still vague.MethodsHospitalized patients with acute respiratory symptoms and with severe acute respiratory syndrome coronavirus 2 (SARS-CoV2)-positive (COVpos) and SARS-CoV2-negative (COVneg) status were included. We assessed adenosine diphosphate (ADP)-, thrombin receptor activator peptide 6 (TRAP)-, and arachidonic acid (AA)-induced platelet reactivity by impedance aggregometry, as well as leukocyte subtype spectrum and platelet-leukocyte aggregates by flow cytometry and inflammatory cytokines by cytometric bead array.ResultsADP-, TRAP-, and AA-induced platelet reactivity was significantly higher in COVpos than in COVneg patients. Disease severity, assessed by sequ...
Cells
Critically ill COVID-19 patients suffer from thromboembolic as well as bleeding events. Endothelial dysfunction, spiking of von Willebrand factor (vWF), and excessive cytokine signaling result in coagulopathy associated with substantial activation of plasmatic clotting factors. Thrombocytopenia secondary to extensive platelet activation is a frequent finding, but abnormal platelet dysfunction may also exist in patients with normal platelet counts. In this study, we performed analyses of platelet function and of von Willebrand factor in critically ill COVID-19 patients (n = 13). Platelet aggregometry was performed using ADP, collagen, epinephrin, and ristocetin. VWF and fibrinogen binding of platelets and CD62 and CD63 expression after thrombin stimulation were analyzed via flow cytometry. In addition, VWF antigen (VWF:Ag), collagen binding capacity (VWF:CB), and multimer analysis were performed next to routine coagulation parameters. All patients exhibited reduced platelet aggregati...
Thrombosis in COVID-19 infection: Role of platelet activation-mediated immunity
Thrombosis Journal
Background Thrombosis plays an important role in the Coronavrus Disease 2019 (COVID-19) infection-related complications such as acute respiratory distress syndrome and myocardial infarction. Multiple factors such as oxygen demand injuries, endothelial cells injury related to infection, and plaque formation. Main body Platelets obtained from the patients may have severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA, showing that the increased activation potential recommends platelet can be hyper-activated in severely ill SARS-CoV-2 cases. Platelets contain multiple receptors that interact with specific ligands. Pathogen’s receptors such as Toll-like receptors (TLRs), NOD-like receptor, C-type lectin receptor family, glycoprotein (GP) such as GPαIIbβ3 and GPIbα which allow pathogens to interact with platelets. Platelet TLRs and NOD2 are involved in platelet activation and thrombosis. Accordingly, TLRs are critical receptors that could recognize various endogenous damage-as...
Blood Advances
Mild thrombocytopenia, changes in platelet gene expression, enhanced platelet functionality, and presence of platelet-rich thrombi in the lung have been associated with thromboinflammatory complications of patients with COVID-19. However, whether severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) gets internalized by platelets and directly alters their behavior and function in infected patients remains elusive. Here, we investigated platelet parameters and the presence of viral material in platelets from a prospective cohort of 29 patients with severe COVID-19 admitted to an intensive care unit. A combination of specific assays, tandem mass spectrometry, and flow cytometry indicated high levels of protein and lipid platelet activation markers in the plasma from patients with severe COVID-19 associated with an increase of proinflammatory cytokines and leukocyte-platelets interactions. Platelets were partly desensitized, as shown by a significant reduction of αIIbβ3 activati...
Immature platelets as a biomarker for disease severity and mortality in COVID‐19 patients
British Journal of Haematology, 2021
SummaryCOVID‐19, caused by SARS‐CoV‐2, is a contagious life‐threatening viral disease that has killed more than three million people worldwide to date. Attempts have been made to identify biomarker(s) to stratify disease severity and improve treatment and resource allocation. Patients with SARS‐COV‐2 infection manifest with a higher inflammatory response and platelet hyperreactivity; this raises the question of the role of thrombopoiesis in COVID‐19 infection. Immature platelet fraction (IPF, %) and immature platelet counts (IPC, ×109/l) can be used to assess thrombopoiesis. This study investigates whether the level of thrombopoiesis correlates with COVID‐19 severity. A large cohort of 678 well‐characterized COVID‐19 patients was analyzed, including 658 (97%) hospitalized and 139 (21%) admitted to the intensive care unit (ICU). Elevated percentage IPF at presentation was predictive of length of hospitalization (P < 0·01) and ICU admission (P < 0·05). Additionally, percentage I...