Neutrophil extracellular traps and von Willebrand factor are allies that negatively influence COVID‐19 outcomes

Abstract

Dear Editor, Complex interactions between various processes have arisen as key elements underlying the pathophysiology of coronavirus disease 2019 (COVID-19). First, immunothrombosis and neutrophil extracellular trap (NET) release contribute to inflammation-associated lung damage and thrombosis, and second, endothelial cell dysfunction participates in the disease-associated coagulopathy. 1,2 In addition, cytokine release syndrome (CRS) dictates adverse clinical outcomes, with interleukin (IL)-6 playing a central role. 3 However, the sequence of events leading to a vicious cycle of synergistic pathways causing unchecked immune activation and thrombus formation have to date not been clearly defined. Here, we investigated the role of NETs, endotheliopathy, hemostatic imbalance, and interleukin-6 (IL-6) release in the severity of the disease, as well as their synergy in patient outcomes. For this purpose, we recruited 142 hospitalized COVID-19 patients from March to May 2020. Infection was confirmed by qRT-PCR testing. Healthy controls (HC, N = 50) were also included. Clinical and demographical variables are reported in Table S1, and biochemical analytical data and cell counts in Table S2. To address whether NETs and von Willebrand factor (VWF)/a disintegrin-like and metalloprotease with thrombospondin type 1 motif 13 (ADAMTS13) axis are associated and contribute to the prognosis of COVID-19 patients, we analyzed plasma cell-free DNA (cfDNA), citrullinated histone H3-DNA (citH3-DNA) complexes (surrogated NET marker), von Willebrand factor antigen (VWF:Ag), von Willebrand factor collagen binding (VWF:CB), ADAMTS13 activity, IL-6 levels, clinical scores, and outcomes. Analysis of NETosis and endotheliopathy markers in the first available sample confirmed a coagulation imbalance in COVID-19 patients versus HC (Figure S1A-F). In addition, NETs and VWF:Ag correlated with neutrophil count, neutrophil/lymphocyte ratio, and with acute-phase reactants and coagulation parameters (Table S3). Importantly, NETs and VWF:Ag/ADAMTS13 This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Neutrophils and COVID-19: Active Participants and Rational Therapeutic Targets

“…Concentrations of a range of NET-associated markers, including cell-free DNA (cfDNA), MPO/NE-DNA complexes and citrullinated histone H3 (CitH3), have all been shown to be significantly increased in the circulation and/or tracheal aspirates of patients with COVID-19 ( 26 , 46 , 65 , 66 , 105 , 134 , 166 – 170 ). As expected for a respiratory infection, NET levels are significantly higher in tracheal aspirates, bronchiolar lavage and BALF samples when compared to plasma ( 65 , 66 ).…”

“…As expected for a respiratory infection, NET levels are significantly higher in tracheal aspirates, bronchiolar lavage and BALF samples when compared to plasma ( 65 , 66 ). In terms of disease severity, patients with severe disease present with significantly higher circulating levels of cfDNA, MPO-DNA complexes and CitH3 when compared to patients with mild to moderate COVID-19 ( 26 , 105 , 170 ), with one study showing a surge in plasma NET markers prior to ICU admission ( 170 ). Thus, in heterogeneous patient cohorts, plasma NET levels positively correlate with clinical severity scoring systems ( 65 , 105 , 170 ) and are negatively associated with the P/F ratio ( 65 ).…”

“…In terms of disease severity, patients with severe disease present with significantly higher circulating levels of cfDNA, MPO-DNA complexes and CitH3 when compared to patients with mild to moderate COVID-19 ( 26 , 105 , 170 ), with one study showing a surge in plasma NET markers prior to ICU admission ( 170 ). Thus, in heterogeneous patient cohorts, plasma NET levels positively correlate with clinical severity scoring systems ( 65 , 105 , 170 ) and are negatively associated with the P/F ratio ( 65 ). Interestingly, concentrations of MPO-DNA complexes have been shown to be significantly higher in plasma samples from male patients when compared to their female counterparts ( 105 ), an observation worthy of further investigation given that male gender is a risk factor for ICU admission and death following SARS-CoV-2 infection ( 171 ).…”

“…To date, discussions regarding the potential use of anti-neutrophil therapies for the treatment of COVID-19 have centred on targeting NETs, whose enhanced generation is likely to contribute to both the pulmonary and extrapulmonary manifestations of severe COVID-19 ( 231 – 233 ). Implicating NETs in the clotting associated complications that have been suggested to account for more than 70% of COVID-19 deaths ( 234 ), significantly higher plasma levels of cfDNA, MPO-DNA complexes and CitH3 have been detected in patients who developed thrombotic events when compared to those who did not ( 105 , 170 ). In addition, excessive NET formation in the lungs has been shown to result in vascular occlusion and disturbed microcirculation ( 26 ).…”

Corona Virus Disease 2019 (COVID-19) as a System-Level Infectious Disease With Distinct Sex Disparities

“…Overall, NETs and VWF/ADAMTS13 axis are essential for thrombosis and inflammation. Given these points, recent evidence shows that the axis is associated with and contributes to the poor prognosis of COVID-19 patients manifested initially by ARDS and then developed to more complex clinical phenotypes, including thrombotic thrombocytopenic purpura-like syndrome, hepatic coagulopathy, MODS, and extensive micro- and macrovascular thrombosis ( 163 , 166 , 177 ). There are increasing global reports considering APLAbs in COVID-19–associated coagulopathy ( 178 ).…”