C5aR1 signaling triggers lung immunopathology in COVID-19 through neutrophil extracellular traps
Bruna M. Silva, … , Paul Proost, Thiago M. Cunha
Bruna M. Silva, … , Paul Proost, Thiago M. Cunha
Published April 27, 2023
Citation Information: J Clin Invest. 2023;133(12):e163105. https://doi.org/10.1172/JCI163105.
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Research Article Inflammation

C5aR1 signaling triggers lung immunopathology in COVID-19 through neutrophil extracellular traps

Abstract

Patients with severe COVID-19 develop acute respiratory distress syndrome (ARDS) that may progress to cytokine storm syndrome, organ dysfunction, and death. Considering that complement component 5a (C5a), through its cellular receptor C5aR1, has potent proinflammatory actions and plays immunopathological roles in inflammatory diseases, we investigated whether the C5a/C5aR1 pathway could be involved in COVID-19 pathophysiology. C5a/C5aR1 signaling increased locally in the lung, especially in neutrophils of critically ill patients with COVID-19 compared with patients with influenza infection, as well as in the lung tissue of K18-hACE2 Tg mice (Tg mice) infected with SARS-CoV-2. Genetic and pharmacological inhibition of C5aR1 signaling ameliorated lung immunopathology in Tg-infected mice. Mechanistically, we found that C5aR1 signaling drives neutrophil extracellular traps-dependent (NETs-dependent) immunopathology. These data confirm the immunopathological role of C5a/C5aR1 signaling in COVID-19 and indicate that antagonists of C5aR1 could be useful for COVID-19 treatment.

Authors

Bruna M. Silva, Giovanni F. Gomes, Flavio P. Veras, Seppe Cambier, Gabriel V.L. Silva, Andreza U. Quadros, Diego B. Caetité, Daniele C. Nascimento, Camilla M. Silva, Juliana C. Silva, Samara Damasceno, Ayda H. Schneider, Fabio Beretta, Sabrina S. Batah, Icaro M.S. Castro, Isadora M. Paiva, Tamara Rodrigues, Ana Salina, Ronaldo Martins, Guilherme C.M. Cebinelli, Naira L. Bibo, Daniel M. Jorge, Helder I. Nakaya, Dario S. Zamboni, Luiz O. Leiria, Alexandre T. Fabro, José C. Alves-Filho, Eurico Arruda, Paulo Louzada-Junior, Renê D. Oliveira, Larissa D. Cunha, Pierre Van Mol, Lore Vanderbeke, Simon Feys, Els Wauters, Laura Brandolini, Andrea Aramini, Fernando Q. Cunha, Jörg Köhl, Marcello Allegretti, Diether Lambrechts, Joost Wauters, Paul Proost, Thiago M. Cunha

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Figure 7

Intratracheal instillation with C5a induced lung immunopathology via C5aR1 signaling and NETs.

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Intratracheal instillation with C5a induced lung immunopathology via C5a...
(A) C57/BL6 mice were treated twice with vehicle, DNAse (Pulmozyme, 10 mg/kg, s.c.), or C5aR1 antagonist (DF2593A, 3 mg/kg, orally), 24 hours and 1 hour before the intratracheal instillation of rmC5a (400 ng). (B) Lung slices from the control group or mice challenged with rmC5a and treated with vehicle, DNAse, or C5aR1 antagonist (DF2593A) were stained with H&E for evaluation of histological changes. (C) Quantification of the lung septal area fraction (n = 5/group). (D) Lung slices from the control group or from mice challenged with rmC5a and treated with vehicle, DNAse, or C5aR1 antagonist (DF2593A) were costained for nuclei (DAPI, blue), H3Cit (green), and MPO (red) markers. (E) NET quantification by the MPO-DNA PicoGreen assay in the supernatant of the lung homogenate (n = 5–6/group). (F) ELISA assays were performed to detect CCL2, CCL3, CCL4, CXCL1, and IL-6 levels in lung homogenate (n = 5–6/group). Data are shown as the mean ± SEM. P values were determined by 1-way ANOVA followed by Bonferroni’s posthoc test (C, E, and F).