Overproduction of ROS participates in chronic bronchitis and the development of mucus plugging by stimulating the production of mucin genes like MUC5b and MUC5ac. 78,79 Production of pro-inflammatory factors is promoted by oxidative stress through the NF-κB and the dissociation of the inhibitor of NF-κB (IκB)/NF-κB complex in airway epithelial cells and macrophages of COPD patients.80 Here, MUC5AC is linked to chronic bronchitis.