TNF and inflammation: In this phase, M1 macrophages have been reported to produce inflammatory cytokines, chemokines, and toxic molecules such as tumor necrosis factor-α (TNF-α), interleukin-1 β (IL-1β), IL-6, monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory protein 2 (MIP-2), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and reactive oxygen species (ROS), which are associated with the recruitment of inflammatory cells, including monocytes and neutrophils, and the promotion of airway inflammation, antimicrobial activity, and lung tissue injury [8,18].