High serum granulocyte-colony stimulating factor characterises neutrophilic COPD exacerbations associated with dysbiosis.

COPD exacerbations are heterogeneous and can be triggered by bacterial, viral, or noninfectious insults. Exacerbations are also heterogeneous in neutrophilic or eosinophilic inflammatory responses. A noninvasive peripheral biomarker of COPD exacerbations characterised by bacterial/neutrophilic inflammation is lacking. Granulocyte-colony stimulating factor (G-CSF) is a key cytokine elevated during bacterial infection and mediates survival, proliferation, differentiation and function of neutrophils. We hypothesised that high peripheral G-CSF would be indicative of COPD exacerbations with a neutrophilic and bacterial phenotype associated with microbial dysbiosis. Serum G-CSF was measured during hospitalised exacerbation (day 0 or D0) and after 30 days of recovery (Day30 or D30) in 37 subjects. In a second cohort, serum and sputum cytokines were measured in 59 COPD patients during stable disease, at exacerbation, and at 2-weeks and 6-weeks following exacerbation. Serum G-CSF was increased during exacerbation in a subset of patients. These exacerbations were enriched for bacterial but not viral or type-2 biologies. The median serum G-CSF level was 1.6-fold higher in bacterial exacerbation compared to nonbacterial exacerbation (22 pg·mL High serum G-CSF enriches for COPD exacerbations characterised by neutrophilic inflammation with underlying bacterial dysbiosis.

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Conflict of interest: A. Chakrabarti reports personal fees from and stock in Genentech, Inc., during the conduct of the study and outside the submitted work. Conflict of interest: J.S. Mar reports personal fees from and equity in Genentech, Inc., outside the submitted work. Conflict of interest: D.F. Choy is an employee of Genentech, Inc. Conflict of interest: Y. Cao reports personal fees from and stock in Genentech, Inc., during the conduct of the study and outside the submitted work. Conflict of interest: N. Rathore reports personal fees from and stock in Genentech, Inc., during the conduct of the study and outside the submitted work. Conflict of interest: X. Yang reports personal fees from Genentech, Inc., during the conduct of the study and outside the submitted work. Conflict of interest: G.W. Tew reports personal fees from Genentech, Inc., during the conduct of the study and outside the submitted work. Conflict of interest: O. Li is a salaried employee of Genentech, Inc. and received nonfinancial support from Genentech, Inc., during the conduct of the study. Conflict of interest: P.G. Woodruff reports consulting fees from Regeneron, Sanofi, Glenmark Pharma, Theravance and NGM Pharma, and visiting professor honoraria from Amgen and Genentech, outside the submitted work. Conflict of interest: C.E. Brightling is an employee of the University of Leicester. Conflict of interest: M. Grimbaldeston is an employee of Genentech, Inc., and reports personal fees and nonfinancial support during the conduct of the study. Conflict of interest: S.A. Christenson reports consulting fees from AstraZeneca, GlaxoSmithKline, Amgen and Glenmark; personal fees for invited lectures from Sunovion and Genentech; and personal fees for writing for UpToDate, all outside the submitted work. Conflict of interest: M. Bafadhel reports grants from AstraZeneca; honoraria for consulting and advisory boards, as well as travel to conferences, from AstraZeneca, Chiesi and GSK. She is a scientific advisor to and minor shareholder in AlbusHealth, all outside the submitted work. Conflict of interest: C.M. Rosenberger reports personal fees from and stock in Genentech, Inc., during the conduct of the study and outside the submitted work.