The bacterial load in the lungs of mice in the XPa + COPD (log10 2.62 ± 0.51) and COPD + XPa (log10 2.29 ± 1.23) groups decreased (**P < 0.01) compared to that in the COPD group (log10 4.27 ± 0.84), which hinted at the potential for clinical application of XPa. The gene discussed is XPA; the disease is chronic obstructive pulmonary disease.