SOD1 and chronic obstructive pulmonary disease: We also found that the MPO and 8-iso-PGF2α levels in induced sputum were negatively correlated with lung function and that the SOD, MPO, and 8-iso-PGF2α levels in induced sputum were negatively correlated with glycerophospholipids (choline, NMethy, and 1-LGPC) in patients with stable COPD.