Project description:Thrombotic complications are frequent in COVID-19 and contribute significantly to mortality and morbidity. We review several mechanisms of hypercoagulability in sepsis that may be upregulated in COVID-19. These include immune-mediated thrombotic mechanisms, complement activation, macrophage activation syndrome, antiphospholipid antibody syndrome, hyperferritinemia, and renin-angiotensin system dysregulation. We highlight biomarkers within each pathway with potential prognostic value in COVID-19. Lastly, recent observational studies have evaluated a role for the expanded use of therapeutic anticoagulation in COVID-19. We review strengths and weaknesses of these studies, and we also discuss the hypothetical benefit and anticipated challenges of fibrinolytic therapy in COVID-19.
Project description:The SARS-CoV-2 virus caused a global pandemic within weeks. Many patients with severe COVID-19 present with coagulation abnormalities, including increase D-dimers. This coagulopathy is associated with an increased risk of death. Furthermore, a substantial proportion of patients with severe COVID-19 develop sometimes unrecognized, venous thromboembolic complications. A better understanding of COVID-19 pathophysiology, in particular hemostatic disorders, will help to choose appropriate treatment strategies. A rigorous thrombotic risk assessment and the implementation of a suitable anticoagulation strategy are required. We review here the characteristics of COVID-19 coagulation laboratory findings in affected patients, the incidence of thromboembolic events and their specificities, and potential therapeutic interventions.
Project description:Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections cause coronavirus disease 2019 (COVID-19) and are associated with inflammation and coagulopathy and high incidence of thrombosis. Myeloid cells (Mϕ) help coordinate the initial immune response in COVID-19. Although we appreciate that Mϕ lie at the nexus of inflammation and thrombosis, the mechanisms that unite the two in COVID-19 remain largely unknown. In this study, we employed systems biology approaches including proteomics, transcriptomics, and mass cytometry to define the circulating proteome and circulating immune cell phenotypes in subjects with COVID-19. In a cohort of COVID-19 subjects (n=35), circulating markers of inflammation (CCL23, IL-6) and vascular dysfunction (ACE2, tissue factor [TF]) were elevated in subjects with severe compared with mild COVID-19. Additionally, although the total white blood cell (WBC) counts were similar between COVID-19 groups, CD14+ monocytes from severe COVID-19 subjects expressed more TF. At baseline, transcriptomics demonstrated increased IL-6, CCL3, ACOD1, C5AR1, C5AR2, and TF in severe COVID-19 subjects compared with controls. Using “stress” transcriptomics, we found that circulating immune cells from severe COVID-19 subjects had evidence of profound immune paralysis with greatly reduced transcriptional activation and release of inflammatory markers in response to Toll-like receptor (TLR) activation. Finally, sera from severe (but not mild) COVID-19 subjects activated human monocytes and induced TF expression. Taken together, these observations further elucidate the pathological mechanisms that underlie immune dysfunction and coagulation abnormalities in COVID-19, contributing to our growing understanding of SARS-CoV-2 infections that could also be leveraged to develop novel diagnostic and therapeutic strategies.
Project description:Many patients who are diagnosed with coronavirus disease 2019 (COVID-19) suffer from venous thromboembolic complications despite the use of stringent anticoagulant prophylaxis. Studies on the exact mechanism(s) underlying thrombosis in COVID-19 are limited as animal models commonly used to study venous thrombosis pathophysiology (i.e. rats and mice) are naturally not susceptible to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Ferrets are susceptible to SARS-CoV-2 infection, successfully used to study virus transmission, and were previously used to study activation of coagulation and thrombosis during influenza virus infection. Here, we used plasma and lung material from SARS-CoV-2-inoculated ferrets to explore their use in studying COVID-19-associated changes in coagulation and thrombosis. Lungs of ferrets inoculated intranasally with SARS-CoV-2 demonstrated alveolar septa that were mildly expanded by macrophages, and diffuse interstitial histiocytic pneumonia. However, no macroscopical or microscopical evidence of vascular thrombosis in the lungs of SARS-CoV-2-inoculated ferrets was found. Longitudinal plasma profiling using a mass spectrometry-based approach revealed minor differences in plasma protein profiles in SARS-CoV-2-inoculated ferrets up to 2 weeks post-infection. Apart from fibrinogen, the majority of plasma coagulation factors were stable and demonstrated a low coefficient of variation. We conclude that while ferrets are an essential and well-suited animal model to study SARS-CoV-2 transmission, their use to study SARS-CoV-2-related changes relevant to thrombotic disease is limited.
Project description:Thrombosis with thrombocytopenia syndrome (TTS) is an extremely rare but potentially serious adverse event following immunization with the adenovirus vector-based COVID-19 vaccines Ad26.COV2.S (Janssen / Johnson & Johnson) or ChAdOx1 (AstraZeneca). However, no cases of TTS have been reported in over 1.5 million individuals who received a second immunization with Ad26.COV2.S in the United States, suggesting that anti-vector immunity may reduce TTS risk. Here we show robust stimulation of platelet activation and coagulation pathways and innate immune pathways in patients with TTS but only transient activation of these pathways following vaccination. We evaluated proteomic profiles in 2 patients with TTS and transcriptomic and proteomic profiles in 20 people following an initial dose and a booster dose of Ad26.COV2.S and in 14 people who received the mRNA vaccines BNT162b2 or mRNA-1273. Initial Ad26.COV2.S vaccination induced transient activation of platelet activation and coagulation pathways and innate proinflammatory pathways that resolved by day 7. TTS patients showed enhanced and sustained upregulation of these pathways, whereas a second immunization with Ad26.COV2.S or a reduced initial dose of Ad26.COV2.S resulted in lower activation of these pathways. These data provide insight into TTS pathogenesis and suggest a potential strategy for reducing TTS risk by lowering the dose of Ad26.COV2.S.
Project description:Platelets may be a target of bacteria and viruses, which can directly or indirectly activate them so promoting thrombosis. In accordance with this, community-acquired pneumonia (CAP) is complicated by ischemia-related vascular disease (myocardial infarction and stroke) in roughly 10% of patients while the incidence of venous thrombosis is uncertain. In CAP platelet biosynthesis of TxA2 is augmented and associated with myocardial infarction; however, a cause-effect relationship is still unclear as unclear is if platelet activation promotes thrombosis or functional changes of coronary tree such vasospasm. Retrospective studies suggested a potential role of aspirin in reducing mortality but the impact on vascular disease is still unknown. Coronavirus disease 2019 (Covid-19) is complicated by thrombosis in roughly 20% of patients with an almost equivalent localization in arterial and venous circulation. Platelet activation seems to have a pivot role in the thrombotic process in Covid-19 as consistently evidenced by its involvement in promoting Tissue Factor up-regulation via leucocyte interaction. Until now, antiplatelet treatment has been scarcely considered for the treatment of Covid-19; interventional trials, however, are in progress to explore this issue. The aim of this review is 1) to compare the type of vascular diseases complicating CAP and Covid-19 2) to assess the different role of platelets in both diseases and 3) to discuss if antiplatelet treatment is potentially useful to improve clinical outcomes.
Project description:Early in the pandemic, COVID-19-related increases in rates of venous and arterial thromboembolism were seen. Many observational studies suggested a benefit of prophylactic anticoagulation for hospitalized patients using various dosing strategies. Randomized trials were initiated to compare the efficacy of these different options in acutely ill and critically ill inpatients as the concept of immune-mediated inflammatory microthrombosis emerged. We present a case-based review of how we approach thromboembolic prophylaxis in COVID-19 and briefly discuss the epidemiology, the pathophysiology, and the rare occurrence of vaccine-induced thrombotic thrombocytopenia.
Project description:ObjectivesDuring severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, dramatic endothelial cell damage with pulmonary microvascular thrombosis have been was hypothesized to occur. The aim was to assess whether pulmonary vascular thrombosis (PVT) is due to recurrent thromboembolism from peripheral deep vein thrombosis or to local inflammatory endothelial damage, with a superimposed thrombotic late complication.DesignObservational study.SettingMedical and intensive care unit wards of a teaching hospital.ParticipantsThe authors report a subset of patients included in a prospective institutional study (CovidBiob study) with clinical suspicion of pulmonary vascular thromboembolism.InterventionsComputed tomography pulmonary angiography and evaluation of laboratory markers and coagulation profile.Measurements and main resultsTwenty-eight of 55 (50.9%) patients showed PVT, with a median time interval from symptom onset of 17.5 days. Simultaneous multiple PVTs were identified in 22 patients, with bilateral involvement in 16, mostly affecting segmental/subsegmental pulmonary artery branches (67.8% and 96.4%). Patients with PVT had significantly higher ground glass opacity areas (31.7% [22.9-41] v 17.8% [10.8-22.1], p < 0.001) compared with those without PVT. Remarkably, in all 28 patients, ground glass opacities areas and PVT had an almost perfect spatial overlap. D-dimer level at hospital admission was predictive of PVT.ConclusionsThe findings identified a specific radiologic pattern of coronavirus disease 2019 (COVID-19) pneumonia with a unique spatial distribution of PVT overlapping areas of ground-glass opacities. These findings supported the hypothesis of a pathogenetic relationship between COVID-19 lung inflammation and PVT and challenged the previous definition of pulmonary embolism associated with COVID-19 pneumonia.
Project description:COVID-19, the disease responsible for the devastating pandemic that began at the end of 2019, has been associated with a significantly increased risk of pulmonary thrombosis, even in patients receiving prophylactic anticoagulation. The predilection for thrombosis in COVID-19 may be driven by at least two distinct, but interrelated, processes: a hypercoagulable state responsible for large-vessel thrombosis and thromboembolism and direct vascular and endothelial injury responsible for in situ microvascular thrombosis. The presence of pulmonary thrombosis may explain why hypoxemia is out of proportion to impairment in lung compliance in some patients with COVID-19 pneumonia. Because pulmonary embolism (PE) and COVID-19 pneumonia share many signs and symptoms, diagnosing PE in patients with COVID-19 can be challenging. Given the high mortality and morbidity associated with severe COVID-19 and the concern that aspects of the disease may be driven by thrombosis, many hospital systems have instituted aggressive anticoagulation protocols above standard VTE prophylaxis. In this review, the epidemiologic and pathophysiologic features, diagnosis, and treatment of COVID-19 pulmonary thrombosis and thromboembolism are discussed.