SOD2 and chronic obstructive pulmonary disease: In murine cigarette smoke-induced COPD, the COPD pathogenesis was markedly enhanced in the absence of AhR via mitochondrial dysfunction, decreased levels of antioxidant regulating proteins (i.e., MnSOD and CuZn-SOD) [33], and increased Th1, Th2, and Th17 cells [22].