P. aeruginosa is detectable in the airways of approximately 25–50% of clinically stable COPD patients,39 and most COPD patients have sporadic and intermittent airway infection with P. aeruginosa, which is repeatedly cleared.40 We further measured the protective efficacy of XPa in a COPD mouse model infected with PAO1 (Fig. 7b). This evidence concerns the gene XPA and chronic obstructive pulmonary disease.