HMOX1 and chronic obstructive pulmonary disease: In addition, the smoking status (former or current smoker) in COPD patients may affect the level of transcription of Nrf2 target genes (NQO1, HO1, AKR1C1, AKR1C3) in the bronchial epithelium, in nasal epithelial cells (AKR1B10) and in peripheral blood mononuclear cells (HO-1) whereas none is altered in alveolar macrophages (Sidhaye et al., 2019).