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  • Self-sustaining IL-8 loops drive a prothrombotic neutrophil phenotype in severe COVID-19.

Self-sustaining IL-8 loops drive a prothrombotic neutrophil phenotype in severe COVID-19.

JCI insight (2021-08-18)
Rainer Kaiser, Alexander Leunig, Kami Pekayvaz, Oliver Popp, Markus Joppich, Vivien Polewka, Raphael Escaig, Afra Anjum, Marie-Louise Hoffknecht, Christoph Gold, Sophia Brambs, Anouk Engel, Sven Stockhausen, Viktoria Knottenberg, Anna Titova, Mohamed Haji, Clemens Scherer, Maximilian Muenchhoff, Johannes C Hellmuth, Kathrin Saar, Benjamin Schubert, Anne Hilgendorff, Christian Schulz, Stefan Kääb, Ralf Zimmer, Norbert Hübner, Steffen Massberg, Philipp Mertins, Leo Nicolai, Konstantin Stark
ABSTRACT

Neutrophils provide a critical line of defense in immune responses to various pathogens, inflicting self-damage upon transition to a hyperactivated, procoagulant state. Recent work has highlighted proinflammatory neutrophil phenotypes contributing to lung injury and acute respiratory distress syndrome (ARDS) in patients with coronavirus disease 2019 (COVID-19). Here, we use state-of-the art mass spectrometry-based proteomics and transcriptomic and correlative analyses as well as functional in vitro and in vivo studies to dissect how neutrophils contribute to the progression to severe COVID-19. We identify a reinforcing loop of both systemic and neutrophil intrinsic IL-8 (CXCL8/IL-8) dysregulation, which initiates and perpetuates neutrophil-driven immunopathology. This positive feedback loop of systemic and neutrophil autocrine IL-8 production leads to an activated, prothrombotic neutrophil phenotype characterized by degranulation and neutrophil extracellular trap (NET) formation. In severe COVID-19, neutrophils directly initiate the coagulation and complement cascade, highlighting a link to the immunothrombotic state observed in these patients. Targeting the IL-8-CXCR-1/-2 axis interferes with this vicious cycle and attenuates neutrophil activation, degranulation, NETosis, and IL-8 release. Finally, we show that blocking IL-8-like signaling reduces severe acute respiratory distress syndrome of coronavirus 2 (SARS-CoV-2) spike protein-induced, human ACE2-dependent pulmonary microthrombosis in mice. In summary, our data provide comprehensive insights into the activation mechanisms of neutrophils in COVID-19 and uncover a self-sustaining neutrophil-IL-8 axis as a promising therapeutic target in severe SARS-CoV-2 infection.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Monoclonal Anti-Interleukin-8 antibody produced in mouse, clone 6217, purified immunoglobulin, lyophilized powder
Sigma-Aldrich
Anti-ALPL antibody produced in rabbit, Ab2, Prestige Antibodies® Powered by Atlas Antibodies, affinity isolated antibody, buffered aqueous glycerol solution