In addition Harvey et al. reported that Nrf2 activation improved the phagocytic ability for NTHi by increasing the scavenger receptor MARCO in alveolar macrophages derived from patients with COPD, though it has not been examined whether MARCO protein expression is down-regulated on the surface of alveolar macrophages of COPD compared to control smokers [35]. Here, MARCO is linked to chronic obstructive pulmonary disease.