The Keap1/Nrf2 antioxidant pathway has been implicated in the pathogenesis of various chronic inflammatory diseases.8, 9, 10 Studies have shown that Nrf2 knockout (Nrf2-/-) mice exposed to CS are more susceptible to severe emphysema and apoptosis, accompanied by significantly lower antioxidant enzyme activity compared to wild-type mice.11 This evidence concerns the gene NFE2L2 and pulmonary emphysema.