Azithromycin treatment modifies airway and blood gene expression networks in neutrophilic COPD

Long-term, low dose azithromycin reduces exacerbation frequency in COPD yet the mechanism remains unclear. This study characterises changes to gene expression in patients with neutrophilic COPD in response to long term low dose azithromycin therapy. Patients with neutrophilic COPD (>61% or >162x10^4/mL sputum neutrophils) were randomised to 12 weeks of either azithromycin or placebo treatment. RNA was extracted from sputum and blood collected before (pre) and after (post) treatment. Microarray analysis was performed on blood (n=11 azithromycin; n=11 placebo group) and sputum (n=11 azithromycin group; n=13 placebo group) in a subset of patients who had paired samples from pre and post treatment visits.