TNF and chronic obstructive pulmonary disease: Macrophages are also activated under COPD conditions, releasing chemotactic factors such as CCL2, CXCL8 and CXCL9 [6] or inflammation mediators and cytokines such as TNFα, IL6, IL8, MCP-1, LTB4, reactive oxygen species (ROS) and metalloproteases such as MMP-9 and MMP-12 [7,8,9,10].