TNF and acute respiratory distress syndrome: Macrophages are involved in both the development and resolution of ARDS, in that their function in disease is determined by their polarization state33, M1 macrophages can polarize Th1 cells and secrete TNF-α to promote inflammation, while M2 macrophages can induce Th2 cells to secrete IL-10 to inhibit inflammation and promote inflammatory damage repair33.