The release of neutrophil extracellular traps (NETs) by hyperactive neutrophils is recognized to play an important role in the thromboinflammatory milieu inherent to severe presentations of COVID-19. At the same time, a variety of functional autoantibodies have been observed in individuals with severe COVID-19, where they likely contribute to immunopathology. Here, we aimed to determine the extent to which autoantibodies might target NETs in COVID-19 and, if detected, to elucidate their potential functions and clinical associations. We measured anti-NET antibodies in 328 individuals hospitalized with COVID-19 alongside 48 healthy controls. We found high anti-NET activity in the IgG and IgM fractions of 27% and 60% of patients, respectively. There was a strong correlation between anti–NET IgG and anti–NET IgM. Both anti–NET IgG and anti–NET IgM tracked with high levels of circulating NETs, impaired oxygenation efficiency, and high circulating D-dimer. Furthermore, patients who required mechanical ventilation had a greater burden of anti-NET antibodies than did those not requiring oxygen supplementation. Levels of anti–NET IgG (and, to a lesser extent, anti–NET IgM) demonstrated an inverse correlation with the efficiency of NET degradation by COVID-19 sera. Furthermore, purified IgG from COVID-19 sera with high levels of anti-NET antibodies impaired the ability of healthy control serum to degrade NETs. In summary, many individuals hospitalized with COVID-19 have anti-NET antibodies, which likely impair NET clearance and may potentiate SARS-CoV-2–mediated thromboinflammation.
Yu Zuo, Srilakshmi Yalavarthi, Sherwin A. Navaz, Claire K. Hoy, Alyssa Harbaugh, Kelsey Gockman, Melanie Zuo, Jacqueline A. Madison, Hui Shi, Yogendra Kanthi, Jason S. Knight
Correlation between anti–NET IgG/IgM and circulating markers of NETs.