Von Willebrand Factor and Myeloperoxidase as Laboratory Predictive Markers of In-Hospital Survival in Severe COVID-19 Patients

Background. The severe acute respiratory syndrome of the SARS-CoV-2 virus-mediated coronavirus disease 2019 (COVID-19) highlighted the central role of immunothrombosis. Severe endothelial damage with the release of unusually large multimers of von Willebrand factor (vWF) and subsequent consumption of ADAMTS-13 is described during severe COVID-19. The activation of innate immune cells among which neutrophils contribute to the formation of extracellular neutrophil traps (NETs) and to the release of myeloperoxidase (MPO) potentially contributing to the spread of inflammation and microvascular thrombosis. Objective - to evaluate the ability of vWF, ADAMTS-13 and MPO to predict in-hospital mortality in severe COVID-19 patients needing mechanical ventilation. Methods. We performed a one-center observational study of 79 severe COVID-19 patients entering intensive care unit for mechanical ventilation, examining vWF, ADAMTS-13 and MPO among other potential predictors for in-hospital death. Results. After multivariate analysis, vWF antigen (vWF:Ag) and MPO antigen (MPO:Ag) were finally the single two parameters which increasing values were independently associated with non-survival;vWF:Ag (U/dL): adjusted OR 3.360, 95% CI 1.562-7.228, p = 0.0019;MPO:Ag (ng/ml): adjusted OR 1.062, 95% CI 1.024-1.101, p = 0.0011. From these results a simplified mortality score was derived and patients categorized as having a score value higher or lower that the median value of the score: a high score value was associated with a lower cumulative survival rate (p < 0.0001), 50% of the cases being dead at day 13 post-hospital admission. Conclusions. In severe COVID-19 necessitating mechanical ventilation, increasing values of MPO activity and of vWF antigen tested at admission are associated with poor survival. Copyright © 2022 Izdatel'stvo Meditsina. All rights reserved.

Pathogenetic and prognostic significance of inflammation and altered ADAMTS-13/vWF axis in patients with severe COVID-19

Introduction. Currently, endothelial dysfunction caused by inflammation and immunothrombosisis considered as one of the crucial mechanisms in developing the SARS-CoV-2 virus-mediated coronavirus disease 2019 (COVID-19). A mass endothelial damage followed by release of untypical large quantity of von Willebrand factor (vWF) multimers and subsequent consumption of metalloproteinase ADAMTS-13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) is described during severe COVID-19. The activation of innate immune cells including neutrophils results in formation of neutrophil extracellular traps (NETs) and myeloperoxidase (MPO) release that, in turn, contributes to spread of inflammation and microvascular thrombosis. Aim: to evaluate a pathogenetic role and predictive significance for serum markers of inflammation, endothelial dysfunction and hemostatis activation such as vWF, ADAMTS-13 and MPO for in-hospital mortality in severe COVID-19 patients requiring mechanical lung ventilation. Materials and Methods. There was performed a single-center observational study with 129 severe COVID-19 patients on mechanical lung ventilation at the intensive care unit, by assessing serum in all subjects vWF, ADAMTS-13 as well as in 79 patients MPO level along with other potential predictors for in-hospital mortality. Results. A multivariate analysis revealed that increased serum level for vWF antigen (vWF:Ag) and MPO antigen (MPO:Ag) were significantly and independently related to high mortality probability: vWF:Ag (IU/ml) - adjusted odds ratio (OR) = 3.360;95 % confidence interval (95 % Cl) = 1.562-7,228 (р = 0,0019);MPO:Ag (ng/ml) - adjusted OR = 1.062;95 % = 1.024-1.101 (p = 0.0011). Such data allowed to obtained a simplified mortality score for categorizing patients as those having a higher or lower score compared with the median score level: a high score was associated with lower cumulative survival rate (p < 0.0001), with 50 % of the cases linked to lethal outcome on day 13 post-hospital admission. Conclusion. Severe COVID-19 patients requiring mechanical lung ventilation were found to have elevated level of serum MPO activity and vWF correlating with poor survival.

The role of platelets in antiviral immunity

The main role of platelets is traditionally assigned to participation in hemostasis reactions. In recent years, the data have appeared on the non-hemostatic platelet-related role and their active participation in inflammatory reactions. These platelet functions are predetermined by their ability to activate and secrete various immunomodulatory cytokines and chemokines. In addition, activated platelets can directly interact with viral receptors. Recently, there has been growing the knowledge regarding platelet-related regulation of diverse cell types. The result of this interaction is, among others, the formation of platelet-leukocyte aggregates, the focusing of neutrophils at the sites of injury, and generation of a scaffold for developing extracellular traps. Thus, platelets are not only participants in coagulation processes, but also important players in the inflammatory process. This lecture details the issues of platelets controlling and modulating host response to viral infection, as well as potential targets for therapeutic intervention.

Anticoagulants: dose control methods and inhibitors

These days, anticoagulants are in great demand. They are used as a prophylaxis for thromboembolic complications in various diseases and conditions in general therapeutic practice, cardiology, neurology, as well as obstetrics to manage high-risk pregnancies. The relevance of anticoagulants competent use has come to the fore in connection with the emergence of a new disease – COVID-19 and its serious complications such as developing thrombotic storm, in which the timely applied anticoagulant therapy is the key to the success of therapy. The risk of bleeding should be considered when using any anticoagulant. Age, impaired renal function and concomitant use of antiplatelet agents are common risk factors for bleeding. Moreover, only vitamin K antagonists and heparin have specific antidotes – vitamin K and protamine, respectively. Inhibitors of other anticoagulants are universal presented as inactivated or activated prothrombin complex concentrate and recombinant factor VIIa. Hemodialysis effectively reduces dabigatran concentration, activated charcoal is effective in the case of recent oral administration of lipophilic drugs. Research on new antidotes of currently available anticoagulants is under way, similar to testing of new types of anticoagulants that are sufficiently effective in preventing and treating thromboembolic complications with minimal risk of hemorrhagic. The main contraindication to anticoagulants use is the doctor's ignorance of the mechanisms of drug action and opportunities for suppressing its effect.

COVID-19 and thrombotic microangiopathy

As shown by numerous studies conducted during the pandemic, the severe course of COVID-19 is accompanied by multiple organ failure. Cytokine storm, hypercoagulation, complement hyperactivation and other arms comprise the overall picture of the pathogenesis of the severe disease course. The frequent diagnosis of multiple microvascular thrombosis in lung, heart, and kidneys, as well as the presence of platelet-fibrin thrombi there and signs of terminal organ damage, suggest a possible involvement of thrombotic microangiopathy (TMA) in the development of multiple organ failure. In this regard, it is especially important to timely diagnose TMA and start pathogenetic therapy. These measures can significantly reduce mortality due to the novel disease. Heparins and direct oral anticoagulants are the mainstay for prevention and treatment of venous thromboembolism in patients with COVID-19, but their effectiveness in the presence of TMA is questionable. It has been proven that anticoagulants use in critically ill patients with COVID-19 for prevention of large vessel thrombosis is effective, but their role in the prevention of microthrombosis is not clear. Here we review the currently available information on thrombotic microangiopathy, as well as a review of literature data describing TMA-like conditions in COVID-19, discuss potential pathophysiology of the condition development and proposed therapeutic approaches. © Obstetrics, Gynecology and Reproduction 2021.

Vaccine-induced immune thrombotic thrombocytopenia: Definition, risks with different vaccines, and the regulators’ responses

After the vaccination campaign initiation in Europe and the UK, reports of rare cases of atypical thrombosis, including sinus vein thrombosis and splanchnic venous thrombosis, began to appear in association with the use of AstraZeneca (ChAdOx1) and J&J/Janssen adenovirus vector vaccines. The syndrome called VITT (vaccine-induced immune thrombotic thrombocytopenia) is manifested as thrombosis simultaneously with decreased platelet count, significantly increased D-dimer levels and detected anti-factor 4 platelet (PF4) antibodies. We present a detailed review on the epidemiology, pathogenesis, clinical picture, diagnostics and treatment of VITT, which by its nature is an immune complication similar to the processes occurring in heparin-induced thrombocytopenia (HIT). All international and national organizations and regulatory authorities, including experts in the field of thrombosis and hemostasis and the VITT expert council recommend continuing the prompt mass vaccination against COVID-19 as the only method able to reduce the incidence of severe cases, stop the spread of COVID-19 infection and emergence of new dangerous mutations in the viral genome. Failure to vaccinate poses an incomparably greater risk of fatal thrombotic and inflammatory complications associated with infections, compared with the risks of extremely rare adverse events that can occur after vaccination. It should be noted that information on VITT, described as a sporadic phenomenon of abnormal immune response to some variants of vaccines against COVID-19, cannot be translated to other vaccines (including those registered in the Russian Federation) and, moreover, cannot be a reason to refuse their administration. © 2021 Obstetrics, Gynecology and Reproduction. All rights reserved.

Thrombotic storm, hemostasis disorders and thromboinflammation in COVID-19

The rate of thrombosis and disseminated intravascular coagulation (DIC) has been increasing in COVID-19 patients. Key features related to such condition include minimal or no risk of bleeding, moderate thrombocytopenia, high plasma fibrinogen as well as increased complement components level in the areas of thrombotic microangiopathy. The clinical picture is not typical for classic DIC. This review systematizes the pathogenetic mechanisms of hypercoagulation in sepsis and its extreme forms in patients with COVID-19. The latter consist of the thrombosis-related immune mechanisms, the complement activation, the macrophage activation syndrome, the formation of antiphospholipid antibodies, the hyperferritinemia, and the dysregulation of the renin-angiotensin system. Taking into consideration the pathogenetic mechanisms, the biomarkers had been identified related to the prognosis of the disease development. Patients with pre-existing cardiovascular disease and other risk factors, including obesity, diabetes, hypertension, and aging pose the peak risk of dying from COVID-19. We also summarize new data on platelet and endothelial dysfunction, immunothrombosis, and, as a result, thrombotic storm as essential components of COVID-19 severe features. © 2021 Obstetrics, Gynecology and Reproduction. All rights reserved.

Neutrophil extracellular traps: A role in inflammation and dysregulated hemostasis as well as in patients with COVID-19 and severe obstetric pathology

Numerous studies have proven a close relationship between inflammatory diseases and the state of hypercoagulability. In fact, thromboembolic complications represent one of the main causes of disability and mortality in acute and chronic inflammatory diseases, cancer and obstetric complications. Despite this, the processes of hemostasis and immune responses have long been considered separately;currently, work is underway to identify the molecular basis for a relationship between such systems. It has been identified that various pro-inflammatory stimuli are capable of triggering a coagulation cascade, which in turn modulates inflammatory responses. Neutrophil extracellular traps (NETs) are the networks of histones of extracellular DNA generated by neutrophils in response to inflammatory stimuli. The hemostasis is activated against infection in order to minimize the spread of infection and, if possible, inactivate the infectious agent. Another molecular network is based on fibrin. Over the last 10 years, there has been accumulated a whole body of evidence that NETs and fibrin are able to form a united network within a thrombus, stabilizing each other. Similarities and molecular cross-reactions are also present in the processes of fibrinolysis and lysis of NETs. Both NETs and von Willebrand factor (vWF) are involved in thrombosis as well as inflammation. During the development of these conditions, a series of events occurs in the microvascular network, including endothelial activation, NETs formation, vWF secretion, adhesion, aggregation, and activation of blood cells. The activity of vWF multimers is regulated by the specific metalloproteinase ADAMTS-13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13). Studies have shown that interactions between NETs and vWF can lead to arterial and venous thrombosis and inflammation. In addition, the contents released from activated neutrophils or NETs result in decreased ADAMTS-13 activity, which can occur in both thrombotic microangiopathies and acute ischemic stroke. Recently, NETs have been envisioned as a cause of endothelial damage and immunothrombosis in COVID-19. In addition, vWF and ADAMTS-13 levels predict COVID-19 mortality. In this review, we summarize the biological characteristics and interactions of NETs, vWF, and ADAMTS-13, the effect of NETs on hemostasis regulation and discuss their role in thrombotic conditions, sepsis, COVID-19, and obstetric complications.

The effect of various types of anticoagulant therapy on the reduction of mortality in COVID-19

Coronavirus disease 2019 (COVID-19) is a viral infection that, in severe course, leads to the development of a cytokine storm, systemic inflammatory response and coagulopathy. Unlike other sepsis-associated disseminated intravascular coagulopathy, COVID-19 induced coagulopathy is realized mainly in thrombosis. Researchers around the world are currently developing adequate diagnostic, monitoring and anticoagulant therapy approaches to safely and effectively manage patients with severe COVID-19. The need to develop laboratory monitoring is due to the fact that 20% of patients have changes in hemostasis indicators, while in patients with a severe form of the disease, they are present in 100% of cases. In case of deaths from COVID-19, there is an increase in the concentration of D-dimer and fibrinogen degradation products. Thus, the severity of hemostasis disorders has an important prognostic value. Anticoagulant therapy is included in the list of all recommendations as an effective means of reducing mortality from COVID-19. The questions of the recommended groups and doses of anticoagulant drugs are still open. The approach to the choice of an anticoagulant should be based not only on risk factors, characteristics of the course of the disease, anamnesis, but also on the wishes of the patient during long-term therapy at the post-hospital stage.

Anticoagulant, anti-inflammatory, antiviral and antitumor properties of heparins

Our knowledge regarding chemical structure and properties of heparin and its derivatives, including biological properties in blood plasma, on the cell surface and while interacting with receptors, has been progressively growing. New insights are followed by the expansion of therapeutic opportunities and indications for the use of heparins. There are prerequisites for the creation of new generation drugs with modified properties that reduce a bleeding risk while applied for a non-anticoagulant goal. The non-anticoagulant heparin properties allow to consider it as a candidate for pathogenetic treatment of patients with COVID-19. This review focuses on the anticoagulant and non-anticoagulant heparin properties as well as the underlying molecular mechanisms.

Laboratory monitoring of COVID-19 patients and importance of coagulopathy markers

The pandemic of a novel coronavirus infection COVID-19 has become a real challenge to the mankind and medical community and has raised a number of medical and social issues. Based on the currently available information on COVID-19 clinical cases, it follows that COVID-19 patients in critical condition exhibit a clinical picture of disseminated intravascular coagulation (DIC), septic shock with developing multiple organ failure, which justifies use of anticoagulant therapy in COVID-19 patients. In addition to isolating virus RNA from biological material and polymerase chain reaction diagnostics, use of simple and easily accessible laboratory blood markers is necessary for management of COVID-19 patients. If the activation of coagulation processes is sufficient enough, consumption of platelets and blood clotting factors can be diagnosed by laboratory methods as prolongation of routine blood clotting tests and increasing thrombocytopenia. Hyperfibrinogenemia, increased D-dimer level, prolonged prothrombin time, thrombocytopenia, lymphopenia, leukocytopenia, increased concentration of interleukin-6 and ferritin are observed in most COVID-19 patients. The degree of increase in these changes correlates with severity of the inflammatory process and serves as a prognostically unfavorable sign. Here we discuss value of laboratory monitoring playing an essential role in such pathological crisis that contributes to patient screening, diagnosis as well as further monitoring, treatment and rehabilitation.