Bronchial brushings from COPD patients treated with either placebo or quercetin for 6 months were used to confirm the effects of quercetin on gene expression.<h4>Results</h4>Compared to DMSO, quercetin-treated COPD basal cells showed an increase in TER and regenerated the airway epithelium with more ciliated cells, and less goblet cells and IL-8. Here, CXCL8 is linked to chronic obstructive pulmonary disease.