Neutrophil extracellular traps and thrombogenesis in COVID-19 patients

COVID-19 has caused significant morbidity and mortality around the world. Recent reports point toward the "cytokine storm" as core of pathogenesis in SAR-CoV-2-induced acute lung injury, acute respiratory distress syndrome (ARDS), coagulopathy, and multiorgan failure. We have presented clinical data here wherein cytokine levels in COVID-19 patients do not match typical cytokine storm seen in ARDS. Interestingly, COVID-19 patients in early disease present with hypoxemia with no significant respiratory dysfunction. In addition, it is reported that hospitalized COVID-19 patients have a high incidence of thrombotic complications, especially involving the pulmonary vasculature. We hypothesized that core to pathogenesis of COVID-19 is the dysregulation of neutrophils, which culminates in excessive release of neutrophil extracellular traps (NETs). Recently, an increasing amount of NETs have been seen in sera of severe COVID-19 patients. We have discussed here mechanisms involved which lead to thrombogenesis and vasculitis because of excessive release of NETs.