Objective: NETosis, a suicide mechanism of neutrophils, is an important immune defense mechanism against pathogens, and when uncontrolled, it contributes to severe tissue damage leading to acute lung injury in influenza and severe acute respiratory syndrome-coronavirus-2 infections. Here we aimed to determine whether blocking of C-X-C motif chemokine receptors 1/2 (CXCR1/2) by reparixin prevents in vitro NETosis induced by either recombinant DEK (rDEK), recombinant interleukin-8 (rIL-8) (both interacts with CXCR2 receptor) or the serum of patients with coronavirus disease-2019 (COVID-19).
Materials and Methods: Level of pro-inflammatory cytokines and NETosis markers in the serum of COVID-19 patients were determined by ELISA. NETosis was induced by treating neutrophils with either rDEK, rIL-8 or COVID-19 patients serum in the presence or absence of reparixin, anti-DEK or anti-IL-8 antibodies. Subsequently, myeloperoxidase (MPO) activity, presence of extracellular neutrophil elastase, and morphology of the cells were analyzed to determine NETosis.
Results: IL-8, IL-6, IL-1β, MPO, and citrullinated histone H3 were increased whereas DEK was moderately decreased in the circulation of the COVID-19 patients. Reparixin and the antibodies against either DEK or IL-8 suppressed the NETosis induced by either the patients serums or by the rDEK and rIL-8.
Conclusion: Our results show for the first time that DEK-CXCR2 interaction plays a role in the NETosis and support the use of reparixin as a potential therapeutic strategy in COVID-19.