Atypical response to bacterial coinfection and persistent neutrophilic bronchoalveolar inflammation distinguish critical COVID-19 from influenza

• DOI: 10.1172/jci.insight.155055
• Publication Date: 2021-11-18T17:13:15Z
• Authors: Seppe Cambier; Mieke Metzemaekers; Ana Carolina de C...; Amber Nooyens; Cato Jacobs; Lore Vanderbeke; Bert Malengier-De...; Mieke Gouwy; Elisabeth Heylen; Philippe Meersseman; Greet Hermans; Els Wauters; Alexander Wilmer; Dominique Schols; Patrick Matthys; Ghislain Opdenakker; Rafael Elias Marques; Joost Wauters; Jennifer Vandooren; Paul Proost
• Keywords: Adult; Inflammation; Male; 0301 basic medicine; Neutrophils; Coinfection; Immunology; COVID-19; Bacterial Infections; Middle Aged; Influenza; 3. Good health; 03 medical and health sciences; Influenza, Human; Cytokines; Humans; Female; Bronchoalveolar Lavage Fluid; Lung; Research Article; Aged

Neutrophils are recognized as important circulating effector cells in the pathophysiology of severe coronavirus disease 2019 (COVID-19). However, their role within inflamed lungs is incompletely understood. Here, we collected bronchoalveolar lavage (BAL) fluids and parallel blood samples critically ill COVID-19 patients requiring invasive mechanical ventilation compared BAL fluid parameters with those mechanically ventilated influenza, a non-COVID-19 viral pneumonia cohort. Compared contained increased numbers hyperactivated degranulating neutrophils elevated concentrations cytokines IL-1β, IL-1RA, IL-17A, TNF-α, G-CSF; chemokines CCL7, CXCL1, CXCL8, CXCL11, CXCL12α; protease inhibitors elafin, secretory leukocyte inhibitor, tissue inhibitor metalloproteinases 1. In contrast, α-1 antitrypsin levels net proteolytic activity were comparable influenza fluids. During antibiotic treatment for bacterial coinfections, several activating chemotactic factors monocytes, lymphocytes, NK detected whereas tended to decrease highlighting persistent immunological response coinfections COVID-19. Finally, high suggests considering option.