Moreover, downregulation of nuclear factor erythroid 2-related factor 2 (Nrf2) and Nrf2-related, heme oxygenase-1, and glutamate-cysteine ligase catalytic subunit in the peripheral blood mononuclear cells, as well as elevated 8-isoprostane and decreased reduced glutathione levels were reported in patients with mild to moderate COPD compared with non-COPD controls [99]. Here, HMOX1 is linked to chronic obstructive pulmonary disease.