Neutrophil extracellular traps contribute to immunothrombosis in COVID-19 acute respiratory distress syndrome

Elizabeth A. Middleton, Xue Yan He, Frederik Denorme, Robert A. Campbell, David Ng, Steven P. Salvatore, Maria Mostyka, Amelia Baxter-Stoltzfus, Alain C. Borczuk, Massimo Loda, Mark J. Cody, Bhanu Kanth Manne, Irina Portier, Estelle S. Harris, Aaron C. Petrey, Ellen J. Beswick, Aleah F. Caulin, Anthony Iovino, Lisa M. Abegglen, Andrew S. WeyrichMatthew T. Rondina, Mikala Egeblad, Joshua D. Schiffman, Christian Con Yost

Research output: Contribution to journalArticlepeer-review

856 Scopus citations


COVID-19 affects millions of patients worldwide, with clinical presentation ranging from isolated thrombosis to acute respiratory distress syndrome (ARDS) requiring ventilator support. Neutrophil extracellular traps (NETs) originate from decondensed chromatin released to immobilize pathogens, and they can trigger immunothrombosis. We studied the connection between NETs and COVID-19 severity and progression. We conducted a prospective cohort study of COVID-19 patients (n 5 33) and age- and sex-matched controls (n 5 17). We measured plasma myeloperoxidase (MPO)-DNA complexes (NETs), platelet factor 4, RANTES, and selected cytokines. Three COVID-19 lung autopsies were examined for NETs and platelet involvement. We assessed NET formation ex vivo in COVID-19 neutrophils and in healthy neutrophils incubated with COVID-19 plasma. We also tested the ability of neonatal NET-inhibitory factor (nNIF) to block NET formation induced by COVID-19 plasma. Plasma MPO-DNA complexes increased in COVID-19, with intubation (P < .0001) and death (P < .0005) as outcome. Illness severity correlated directly with plasma MPO-DNA complexes (P 5 .0360), whereas PaO2/fraction of inspired oxygen correlated inversely (P 5 .0340). Soluble and cellular factors triggering NETs were significantly increased in COVID-19, and pulmonary autopsies confirmed NET-containing microthrombi with neutrophil-platelet infiltration. Finally, COVID-19 neutrophils ex vivo displayed excessive NETs at baseline, and COVID-19 plasma triggered NET formation, which was blocked by nNIF. Thus, NETs triggering immunothrombosis may, in part, explain the prothrombotic clinical presentations in COVID-19, and NETs may represent targets for therapeutic intervention.

Original languageEnglish
Pages (from-to)1169-1179
Number of pages11
Issue number10
StatePublished - Sep 3 2020

Bibliographical note

Funding Information:
Conflict-of-interest disclosure: C.C.Y. has received grant funding from PEEL Therapeutics, Inc. during the conduct of this study. In addition, C.C.Y. authored a United States patent (patent no. 10 232023 B2) held by the University of Utah for the use of NET-inhibitory peptides for the “treatment of and prophylaxis against inflammatory disorders,” for which PEEL Therapeutics, Inc. holds the exclusive license. A.I. and L.M.A. are consultants and stock option holders of PEEL Therapeutics, Inc., and A.F.C. and J.D.S. are employees and stock option holders of PEEL Therapeutics, Inc. The remaining authors declare no competing financial interests.

Funding Information:
This work was supported by grants from the National Institutes of Health (NIH)/National Institute of Children’s Health and Development (R01 HD093826 [C.C.Y.]), NIH/National Cancer Institute (5P30CA045508-30 [M.E.]), NIH/National Heart, Lung, and Blood Institute (R01 HL135265 [A.C.P.]; R35 HL145237, R01 HL142804NIA, and R61HL141783 [A.S.W.]), and NIH/National Institute on Aging (K01 AG059892 [R.A.C.]); the University of Utah Triple I Program (E.A.M.); Fonds voor Weten-schappelijk Onderzoek Vlaanderen FWO 12U7818N (F.D.); Animal Cancer Foundation (J.D.S.); Soccer For Hope Foundation (J.D.S.); Closer To Cure Foundation (J.D.S.); and PEEL Therapeutics, Inc (C.C.Y.). This work was also supported, in part, by Merit Review Award I01 CX001696 (M.T.R.) from the US Department of Veterans Affairs Clinical Sciences R&D Service. M.E., X.-Y.H., and D.N. were supported by the William C. and Joyce C. O’Neill Charitable Trust and the Linartz-Meier Family Foundation. This article is the result of work supported with resources and the use of facilities at the George E. Wahlen VA Medical Center.

Publisher Copyright:
© 2020 American Society of Hematology. All rights reserved.

ASJC Scopus subject areas

  • Biochemistry
  • Immunology
  • Hematology
  • Cell Biology


Dive into the research topics of 'Neutrophil extracellular traps contribute to immunothrombosis in COVID-19 acute respiratory distress syndrome'. Together they form a unique fingerprint.

Cite this