The significance of disseminated intravascular coagulation on multiple organ dysfunction during the early stage of acute respiratory distress syndrome

Pathophysiological mechanisms of ARDS: a narrative review from molecular to organ-level perspectives

BACKGROUND

Acute respiratory distress syndrome (ARDS) remains a life-threatening pulmonary condition with persistently high mortality rates despite significant advancements in supportive care. Its complex pathophysiology involves an intricate interplay of molecular and cellular processes, including cytokine storms, oxidative stress, programmed cell death, and disruption of the alveolar-capillary barrier. These mechanisms drive localized lung injury and contribute to systemic inflammatory response syndrome and multiple organ dysfunction syndrome. Unlike prior reviews that primarily focus on isolated mechanisms, this narrative review synthesizes the key pathophysiological processes of ARDS across molecular, cellular, tissue, and organ levels.

MAIN BODY

By integrating classical theories with recent research advancements, we provide a comprehensive analysis of how inflammatory mediators, metabolic reprogramming, oxidative stress, and immune dysregulation synergistically drive ARDS onset and progression. Furthermore, we critically evaluate current evidence-based therapeutic strategies, such as lung-protective ventilation and prone positioning, while exploring innovative therapies, including stem cell therapy, gene therapy, and immunotherapy. We emphasize the significance of ARDS subtypes and their inherent heterogeneity in guiding the development of personalized treatment strategies.

CONCLUSIONS

This narrative review provides fresh perspectives for future research, ultimately enhancing patient outcomes and optimizing management approaches in ARDS.

Anion gap predicting 90-Day mortality and guiding furosemide use in ARDS

The objective of this study was to investigate whether serum anion gap (AG), which may serve as an indicator for multiple organic dysfunctions in the condition of hypoxia, could be utilized as a reliable prognostic marker for short-term mortality and a potential therapeutic target in patients with acute respiratory distress syndrome (ARDS). A retrospective cohort study was conducted using data from the Medical Information Mart for Intensive Care (MIMIC-IV) electronic database (version 2.2), including 11,227 confirmed patients with ARDS. Multivariate Cox proportional hazards analysis revealed a significant association between elevated AG levels and all-cause mortality. After adjusting for confounding factors, elevated AG levels were strongly correlated with 90-day mortality [adjusted hazard ratio (HR) 1.23; 95% confidence interval (CI) 1.10-1.37; P < 0.001]. Restricted cubic splines and Kaplan-Meier curves demonstrated an increased risk of all-cause mortality with higher AG levels. Subgroup analysis results emphasized the significance of furosemide as a pivotal therapeutic option, which was further supported by subsequent Kaplan-Meier curves and Cox proportional hazards analysis showing its protective effects in patients with elevated serum AG levels. Even after adjusting for relevant confounding factors, furosemide continued to exhibit a significant protective effect in the group with the highest AG level (Q4: adjusted HR 0.57; 95% CI 0.50-0.65; P < 0.001); however, no significant protective effect was observed in the intermediate level groups (Q2 and Q3). In summary, this research demonstrated a significant association between heightened serum AG levels and increased mortality risk among ARDS patients, which was mitigated by administration of furosemide.

IMMUNOSUPPRESSION CORRELATES WITH THE DETERIORATION OF SEPSIS-INDUCED DISSEMINATED INTRAVASCULAR COAGULATION

ABSTRACT

Background: The dysregulated host responses play a crucial role in the pathophysiology process of sepsis-induced disseminated intravascular coagulation (DIC). The study aimed to characterize the dynamic alternation of immune-related biomarkers and their relationship with the progression of DIC during sepsis. Methods: A prospective, observational study was conducted in a tertiary care academic hospital. Six hundred forty patients with sepsis were classified into three groups according to the International Society on Thrombosis and Hemostasis (ISTH) score: 383 involved patients without DIC (ISTH = 0), 168 sepsis with nonovert DIC (ISTH = 1-4), and 89 sepsis with overt DIC (ISTH ≥5). Eighteen immune-related biomarkers and six routine coagulation variables were examined at D1, D3, and D7 upon enrollment. The association between the immune parameters and the DIC deterioration was assessed during sepsis. Results: The study showed a 40% coagulation disorder and a 14% incidence of overt DIC in patients with sepsis. The patients with overt DIC displayed pronounced immune disorders from D1 to D7 upon sepsis, which was characterized by the decreased percentage of monocyte HLA-DR (mHLA-DR), increased percentage of regulatory T cells, the levels of procalcitonin, neutrophil CD64 index, and systemic inflammatory cytokines relative to nonovert DIC or non-DIC patients. In multivariate analysis, the combination of anti-inflammatory cytokine IL-10 and mHLA-DR at D1 upon enrollment had a superior predictive value for predicting DIC deterioration in sepsis (area under the curve = 0.87, P < 0.0001). Conclusion: These data illustrate that immunosuppression can crosstalk with coagulation disorder during sepsis and present an additional evaluation tool to predict DIC deterioration.

The Detection of Neutrophil Activation by Automated Blood Cell Counter in Sepsis

Neutrophils serve as the frontline defenders in the host's response to infections. However, the available methods for assessing the activated status of neutrophils are still limited. The immature cells that appear during sepsis are large with complex cytoplasmic components and rich nucleic acids, making them diagnosable by cell population data analysis using the automated cell counter. The changes are expressed as increased forward scattered light, side fluorescence light, and side fluorescence distribution width. Additionally, changes in side fluorescence light may indicate the neutrophil extracellular trap formation and can be useful for the diagnosis of sepsis-associated disseminated intravascular coagulation.

COAGULOPATHY PARAMETERS PREDICTIVE OF OUTCOMES IN SEPSIS-INDUCED ACUTE RESPIRATORY DISTRESS SYNDROME: A SUBANALYSIS OF THE TWO PROSPECTIVE MULTICENTER COHORT STUDIES

ABSTRACT

Background: Although coagulopathy is often observed in acute respiratory distress syndrome (ARDS), its clinical impact remains poorly understood. Objectives: This study aimed to clarify the coagulopathy parameters that are clinically applicable for prognostication and to determine anticoagulant indications in sepsis-induced ARDS. Method: This study enrolled patients with sepsis-derived ARDS from two nationwide multicenter, prospective observational studies. We explored coagulopathy parameters that could predict outcomes in the Focused Outcome Research on Emergency Care for Acute Respiratory Distress Syndrome, Sepsis, and Trauma (FORECAST) cohort, and the defined coagulopathy criteria were validated in the Sepsis Prognostication in Intensive Care Unit and Emergency Room-Intensive Care Unit (SPICE-ICU) cohort. The correlation between anticoagulant use and outcomes was also evaluated. Results: A total of 181 patients with sepsis-derived ARDS in the FORECAST study and 61 patients in the SPICE-ICU study were included. In a preliminary study, we found the set of prothrombin time-international normalized ratio ≥1.4 and platelet count ≤12 × 10 4 /μL, and thrombocytopenia and elongated prothrombin time (TEP) coagulopathy as the best coagulopathy parameters and used it for further analysis; the odds ratio (OR) of TEP coagulopathy for in-hospital mortality adjusted for confounding was 3.84 (95% confidence interval [CI], 1.66-8.87; P = 0.005). In the validation cohort, the adjusted OR for in-hospital mortality was 32.99 (95% CI, 2.60-418.72; P = 0.002). Although patients without TEP coagulopathy showed significant improvements in oxygenation over the first 4 days, patients with TEP coagulopathy showed no significant improvement (ΔPaO 2 /FiO 2 ratio, 24 ± 20 vs. 90 ± 9; P = 0.026). Furthermore, anticoagulant use was significantly correlated with mortality and oxygenation recovery in patients with TEP coagulopathy but not in patients without TEP coagulopathy. Conclusion: Thrombocytopenia and elongated prothrombin time coagulopathy is closely associated with better outcomes and responses to anticoagulant therapy in sepsis-induced ARDS, and our coagulopathy criteria may be clinically useful.

The impact of vascular endothelial glycocalyx on the pathogenesis and treatment of disseminated intravascular coagulation

Disseminated intravascular coagulation (DIC) is a complex disorder characterized by widespread activation of blood clotting mechanisms throughout the body. Understanding the role of vascular endothelial glycocalyx in the pathogenesis and treatment of DIC is crucial for advancing our knowledge in this field. The vascular endothelial glycocalyx is a gel-like layer that coats the inner surface of blood vessels. It plays a significant role in maintaining vascular integrity, regulating fluid balance, and preventing excessive clotting. In the pathogenesis of DIC, the disruption of the vascular endothelial glycocalyx is a key factor. Pathological conditions trigger the activation of enzymes, including heparanase, hyaluronase, and matrix metalloproteinase. This activation leads to glycocalyx degradation, subsequently exposing endothelial cells to procoagulant stimuli. Additionally, the ANGPTs/Tie-2 signaling pathway plays a role in the imbalance between the synthesis and degradation of VEG, exacerbating endothelial dysfunction and DIC. Understanding the mechanisms behind glycocalyx degradation and its impact on DIC can provide valuable insights for the development of targeted therapies. Preservation of the glycocalyx integrity may help prevent the initiation and propagation of DIC. Strategies such as administration of exogenous glycocalyx components, anticoagulant agents, or Tie-2 antibody agents have shown promising results in experimental models. In conclusion, the vascular endothelial glycocalyx plays a crucial role in the pathogenesis and treatment of DIC. Further research in this field is warranted to unravel the complex interactions between the glycocalyx and DIC, ultimately leading to the development of novel therapies.

Evaluation of the Revised ISTH Overt-DIC Score (2018) for Predicting 90-day Mortality in Adult Critically Ill Subjects Undergoing Extracorporeal Membrane Oxygenation

BACKGROUND AND OBJECTIVE

Coagulopathy is a common and serious problem in subjects received extracorporeal membrane oxygenation (ECMO), and this study evaluated whether the 2018 diffuse intravascular coagulation (DIC) score established by the International Society on Thrombosis and Hemostasis (ISTH) is associated with 90-day mortality in adult ECMO subjects.

METHODS

A retrospective study analyzed data from adult subjects receiving ECMO in our hospital from September 2018 to April 2021. Pre-ECMO DIC score and other variables were assessed and compared to predict 90-day mortality.

RESULTS

Among 103 eligible subjects, 55.3% received V-V ECMO and 44.7% received V-A ECMO. The overall 90-day mortality for study subjects was 54.4%, including 45.6% in the V-V group and 65.2% in the V-A group. Multiple logistic regression analysis showed that after adjusting for sex, sepsis, and APACHE II score, pre-ECMO DIC scores in the total and V-V group predicted 90-day mortality (odds ratio(OR): 1.419, 95% confidence interval (CI): 1.101-1.828; OR: 2.562; 95% CI: 1.452-4.520 ). Receiver operating characteristic (ROC) curves displayed that pre-ECMO DIC score of 4 in the total and V-V group was a good predictor of 90-day mortality (area under the curve (AUC)=0.706, 95% CI:0.606-0.806; AUC=0.737, 95% CI:0.604-0.870). Kaplan-Meier curves demonstrated the 90-day mortality of subjects with pre-ECMO DIC score ≥ 4 in the total and V-V group was higher than that of subjects with DIC score < 4 (hazard ratio (HR): 2.821; 95% CI: 1.632-4.879; HR: 3.864,95% CI: 1.660-8.992).

CONCLUSION

The pre-ECMO ISTH DIC score was associated with 90-day mortality in adult subjects undergoing ECMO, particularly in the V-V ECMO group.

Perioperative Pulmonary Atelectasis: Part I. Biology and Mechanisms

Pulmonary atelectasis is common in the perioperative period. Physiologically, it is produced when collapsing forces derived from positive pleural pressure and surface tension overcome expanding forces from alveolar pressure and parenchymal tethering. Atelectasis impairs blood oxygenation and reduces lung compliance. It is increasingly recognized that it can also induce local tissue biologic responses, such as inflammation, local immune dysfunction, and damage of the alveolar-capillary barrier, with potential loss of lung fluid clearance, increased lung protein permeability, and susceptibility to infection, factors that can initiate or exaggerate lung injury. Mechanical ventilation of a heterogeneously aerated lung (e.g., in the presence of atelectatic lung tissue) involves biomechanical processes that may precipitate further lung damage: concentration of mechanical forces, propagation of gas-liquid interfaces, and remote overdistension. Knowledge of such pathophysiologic mechanisms of atelectasis and their consequences in the healthy and diseased lung should guide optimal clinical management.

SARS-CoV-2 and Plasma Hypercoagulability

Hypercoagulability has emerged as a prominent consequence of COVID-19. This presents challenges not only in the clinic, but also in thrombosis research. Health and safety considerations, the status of the blood and plasma supply, the infection status of individual donors, and the mechanisms by which SARS-CoV-2 activates coagulation are all of concern. In this review, we discuss these topics from the basic research perspective. As in other respiratory illnesses, blood and plasma from COVID-19 positive patients carries minimal to no risk of infection to practitioners or researchers. There are currently no special regulatory mandates directing individual donors (for research purposes), blood centers/services or vendors (for blood products for research) to test blood/plasma for SARS-CoV-2 or antibodies. We discuss current theories about how SARS-CoV-2 leads to hyper-coagulant state in severe cases of COVID-19. Our current understanding of the mechanisms behind COVID-19 associated thromboembolic events have centered around three different pathways: (1) direct activation of platelets, enhancing coagulation; (2) direct infection and indirect activation (e.g. cytokine storm) of endothelial cells by SARS-CoV-2, shifting endothelium from an anti-thrombotic to a pro-thrombotic state; and (3) direct activation of complement pathways, promoting thrombin generation. Further investigation on how SARS-CoV-2 affects thrombosis in COVID-19 patients may bring novel anti-thrombotic therapies to combat the disease.

The year in basic vascular biology research: from mechanoreceptors and neutrophil extracellular traps to smartphone data and omics

2020 has been an extraordinary year. The emergence of COVID-19 has driven urgent research in pulmonary and cardiovascular science and other fields. It has also shaped the way that we work with many experimental laboratories shutting down for several months, while bioinformatics approaches and other large data projects have gained prominence. Despite these setbacks, vascular biology research is stronger than ever. On behalf of the European Society of Cardiology Council for Basic Cardiovascular Science (ESC CBCS), here we review some of the vascular biology research highlights for 2020. This review is not exhaustive and there are many outstanding vascular biology publications that we were unable to cite due to page limits. Notwithstanding this, we have provided a snapshot of vascular biology research excellence in 2020 and identify topics that are in the ascendency and likely to gain prominence in coming years.

The specification of zebrafish (Danio rerio) heart electrocardiogram index characteristic responses to different types of pollutants

Water quality was highly affected by common pollutants. Metals, pesticides and small molecules are ubiquitous pollutants. Advancement in engineering technology (computer-based monitoring systems) increased the efficiency of quantifying toxicity of different chemicals in an organism. The cardiovascular system reflects internal and external stress of an organism, and electrocardiogram (ECG) data reliably measure external stress. As ECG data can accurately reflect the physiological conditions of organisms, and zebrafish (Danio rerio) are considered to be good models for cardiovascular research, it is hypothesized that ECG parameters of zebrafish could indicate the toxicity of water-borne chemicals. To achieve this, we treated zebrafish with different concentrations of target chemicals (CuSO₄, C₁₀H₁₉O₆PS₂ and NH₄Cl) for 48 h and ECG data were measured. P-wave, R-wave, T-wave, PR-interval, QRS-complex and QT-interval data were the focus of this study. The results of self-organizing maps and Pearson correlation analysis indicate that the QRS-complex can be used as an indicator for CuSO₄ stress. The QT-interval could be used to assess the C₁₀H₁₉O₆PS₂ stress. The QT-interval and P-wave can be used to evaluate the NH₄Cl stress. Responses of zebrafish ECG parameters were identical with other vertebrate model, and were specific to toxicant types. It is proved that zebrafish heart ECG index could be used as a potential indicator in early detection of environmental stress.

Recent advances in the research and management of sepsis-associated DIC

Disseminated intravascular coagulation (DIC) is a common and life-threatening complication in sepsis. Sepsis-associated DIC is recognized as the systemic activation in coagulation with suppressed fibrinolysis that leads to organ dysfunction in combination with systemic intravascular inflammation. In this process, thrombin contributes a key role in connecting both coagulation and inflammation. Endothelial injury, a result of sepsis, causes DIC due to the effect of multiple activated factors that include neutrophils, platelets, and damage-associated molecular patterns. Recent advances in the understanding of pathophysiology have made it possible to diagnose sepsis-associated DIC at earlier timing with better accuracy. However, progress in the treatment is still limited, and new therapeutics for sepsis-associated DIC are needed.

Thrombotic Complications of COVID-19 Infection: A Review

The novel coronavirus (severe acute respiratory syndrome CoV-2 [SARS-CoV-2]), also known as COVID-19, is a single-stranded enveloped RNA virus that created a Public Health Emergency of International Concern in January 2020, with a global case burden of over 15 million in just 7 months. Infected patients develop a wide range of clinical manifestations-typically presenting with fever, cough, myalgia, and fatigue. Severely ill patients may fall victim to acute respiratory distress syndrome, acute heart injuries, neurological manifestations, or complications due to secondary infections. These critically ill patients are also found to have disrupted coagulation function, predisposing them to consumptive coagulopathies, and both venous and thromboembolic complications. Common laboratory findings include thrombocytopenia, elevated D-dimer, fibrin degradation products, and fibrinogen, all of which have been associated with greater disease severity. Many cases of pulmonary embolism have been noted, along with deep vein thrombosis, ischemic stroke, myocardial infarction, and systemic arterial embolism. The pathogenesis of coronavirus has not been completely elucidated, but the virus is known to cause excessive inflammation, endothelial injury, hypoxia, and disseminated intravascular coagulation, all of which contribute to thrombosis formation. These patients are also faced with prolonged immobilization while staying in the hospital or intensive care unit. It is important to have a high degree of suspicion for thrombotic complications as patients may rapidly deteriorate in severe cases. Evidence suggests that prophylaxis with anticoagulation may lead to a lower risk of mortality, although it does not eliminate the possibility. The risks and benefits of anticoagulation treatment should be considered in each case. Patients should be regularly evaluated for bleeding risks and thrombotic complications.

Endothelial dysfunction in COVID-19: a position paper of the ESC Working Group for Atherosclerosis and Vascular Biology, and the ESC Council of Basic Cardiovascular Science

The COVID-19 pandemic is an unprecedented healthcare emergency causing mortality and illness across the world. Although primarily affecting the lungs, the SARS-CoV-2 virus also affects the cardiovascular system. In addition to cardiac effects, e.g. myocarditis, arrhythmias, and myocardial damage, the vasculature is affected in COVID-19, both directly by the SARS-CoV-2 virus, and indirectly as a result of a systemic inflammatory cytokine storm. This includes the role of the vascular endothelium in the recruitment of inflammatory leucocytes where they contribute to tissue damage and cytokine release, which are key drivers of acute respiratory distress syndrome (ARDS), in disseminated intravascular coagulation, and cardiovascular complications in COVID-19. There is also evidence linking endothelial cells (ECs) to SARS-CoV-2 infection including: (i) the expression and function of its receptor angiotensin-converting enzyme 2 (ACE2) in the vasculature; (ii) the prevalence of a Kawasaki disease-like syndrome (vasculitis) in COVID-19; and (iii) evidence of EC infection with SARS-CoV-2 in patients with fatal COVID-19. Here, the Working Group on Atherosclerosis and Vascular Biology together with the Council of Basic Cardiovascular Science of the European Society of Cardiology provide a Position Statement on the importance of the endothelium in the underlying pathophysiology behind the clinical presentation in COVID-19 and identify key questions for future research to address. We propose that endothelial biomarkers and tests of function (e.g. flow-mediated dilatation) should be evaluated for their usefulness in the risk stratification of COVID-19 patients. A better understanding of the effects of SARS-CoV-2 on endothelial biology in both the micro- and macrovasculature is required, and endothelial function testing should be considered in the follow-up of convalescent COVID-19 patients for early detection of long-term cardiovascular complications.

Coagulopathy and Thrombosis as a Result of Severe COVID-19 Infection: A Microvascular Focus

Coronavirus disease of 2019 (COVID-19) is the clinical manifestation of the respiratory infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). While primarily recognized as a respiratory disease, it is clear that COVID-19 is systemic illness impacting multiple organ systems. One defining clinical feature of COVID-19 has been the high incidence of thrombotic events. The underlying processes and risk factors for the occurrence of thrombotic events in COVID-19 remain inadequately understood. While severe bacterial, viral, or fungal infections are well recognized to activate the coagulation system, COVID-19-associated coagulopathy is likely to have unique mechanistic features. Inflammatory-driven processes are likely primary drivers of coagulopathy in COVID-19, but the exact mechanisms linking inflammation to dysregulated hemostasis and thrombosis are yet to be delineated. Cumulative findings of microvascular thrombosis has raised question if the endothelium and microvasculature should be a point of investigative focus. von Willebrand factor (VWF) and its protease, a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS-13), play important role in the maintenance of microvascular hemostasis. In inflammatory conditions, imbalanced VWF-ADAMTS-13 characterized by elevated VWF levels and inhibited and/or reduced activity of ADAMTS-13 has been reported. Also, an imbalance between ADAMTS-13 activity and VWF antigen is associated with organ dysfunction and death in patients with systemic inflammation. A thorough understanding of VWF-ADAMTS-13 interactions during early and advanced phases of COVID-19 could help better define the pathophysiology, guide thromboprophylaxis and treatment, and improve clinical prognosis.

Host-pathogen interaction in COVID-19: Pathogenesis, potential therapeutics and vaccination strategies

The current coronavirus pandemic, COVID-19, is the third outbreak of disease caused by the coronavirus family, after Severe Acute Respiratory Syndrome and Middle East Respiratory Syndrome. It is an acute infectious disease caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). This severe disease is characterised by acute respiratory distress syndrome, septic shock, metabolic acidosis, coagulation dysfunction, and multiple organ dysfunction syndromes. Currently, no drugs or vaccines exist against the disease and the only course of treatment is symptom management involving mechanical ventilation, immune suppressants, and repurposed drugs. The severe form of the disease has a relatively high mortality rate. The last six months have seen an explosion of information related to the host receptors, virus transmission, virus structure-function relationships, pathophysiology, co-morbidities, immune response, treatment and the most promising vaccines. This review takes a critically comprehensive look at various aspects of the host-pathogen interaction in COVID-19. We examine the genomic aspects of SARS-CoV-2, modulation of innate and adaptive immunity, complement-triggered microangiopathy, and host transmission modalities. We also examine its pathophysiological impact during pregnancy, in addition to emphasizing various gaps in our knowledge. The lessons learnt from various clinical trials involving repurposed drugs have been summarised. We also highlight the rationale and likely success of the most promising vaccine candidates.

IFCC Interim Guidelines on Biochemical/Hematological Monitoring of COVID-19 Patients

Routine biochemical and hematological tests have been reported to be useful in the stratification and prognostication of pediatric and adult patients with diagnosed coronavirus disease (COVID-19), correlating with poor outcomes such as the need for mechanical ventilation or intensive care, progression to multisystem organ failure, and/or death. While these tests are already well established in most clinical laboratories, there is still debate regarding their clinical value in the management of COVID-19, particularly in pediatrics, as well as the value of composite clinical risk scores in COVID-19 prognostication. This document by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) Task Force on COVID-19 provides interim guidance on: (A) clinical indications for testing, (B) recommendations for test selection and interpretation, (C) considerations in test interpretation, and (D) current limitations of biochemical/hematological monitoring of COVID-19 patients. These evidence-based recommendations will provide practical guidance to clinical laboratories worldwide, underscoring the contribution of biochemical and hematological testing to our collective pandemic response.

Inference from longitudinal laboratory tests characterizes temporal evolution of COVID-19-associated coagulopathy (CAC)

Temporal inference from laboratory testing results and triangulation with clinical outcomes extracted from unstructured electronic health record (EHR) provider notes is integral to advancing precision medicine. Here, we studied 246 SARS-CoV-2 PCR-positive (COVID_pos) patients and propensity-matched 2460 SARS-CoV-2 PCR-negative (COVID_neg) patients subjected to around 700,000 lab tests cumulatively across 194 assays. Compared to COVID_neg patients at the time of diagnostic testing, COVID_pos patients tended to have higher plasma fibrinogen levels and lower platelet counts. However, as the infection evolves, COVID_pos patients distinctively show declining fibrinogen, increasing platelet counts, and lower white blood cell counts. Augmented curation of EHRs suggests that only a minority of COVID_pos patients develop thromboembolism, and rarely, disseminated intravascular coagulopathy (DIC), with patients generally not displaying platelet reductions typical of consumptive coagulopathies. These temporal trends provide fine-grained resolution into COVID-19 associated coagulopathy (CAC) and set the stage for personalizing thromboprophylaxis.

Devilishly radical NETwork in COVID-19: Oxidative stress, neutrophil extracellular traps (NETs), and T cell suppression

Pandemic coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and poses an unprecedented challenge to healthcare systems due to the lack of a vaccine and specific treatment options. Accordingly, there is an urgent need to understand precisely the pathogenic mechanisms underlying this multifaceted disease. There is increasing evidence that the immune system reacts insufficiently to SARS-CoV-2 and thus contributes to organ damage and to lethality. In this review, we suggest that the overwhelming production of reactive oxygen species (ROS) resulting in oxidative stress is a major cause of local or systemic tissue damage that leads to severe COVID-19. It increases the formation of neutrophil extracellular traps (NETs) and suppresses the adaptive arm of the immune system, i.e. T cells that are necessary to kill virus-infected cells. This creates a vicious cycle that prevents a specific immune response against SARS-CoV-2. The key role of oxidative stress in the pathogenesis of severe COVID-19 implies that therapeutic counterbalancing of ROS by antioxidants such as vitamin C or NAC and/or by antagonizing ROS production by cells of the mononuclear phagocyte system (MPS) and neutrophil granulocytes and/or by blocking of TNF-α can prevent COVID-19 from becoming severe. Controlled clinical trials and preclinical models of COVID-19 are needed to evaluate this hypothesis.