CXCL8 and chronic obstructive pulmonary disease: ROS mediated by CS-induced oxidative stress activates the p38 MAPK and NFκB signaling pathways in both the epithelial cells and the alveolar macrophages of COPD patients and enhances the expression of inflammatory mediators, such as IL8, TNF, and the granulocyte-macrophage colony-stimulating factor [42,43].