TNF and acute respiratory distress syndrome: TLR4 triggers the activation of nuclear factor-κB (NF-κB) signaling pathway, which induces the production of proinflammatory cytokines and chemokines, such as tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β), and macrophage inflammatory protein-2 (MIP-2), and subsequently leads to the recruitment of inflammatory cells in the lung and finally leads to the occurrence of ALI [5–7].