Figure 6. Schematic of the model. LPS first induces macrophage polarization to M1, which produces and releases TNFα to recruit and activate neutrophils, which further produced and secreted TNFα in an autocrine manner to mediate the early pro-inflammatory responses after ALI. Neutrophils also produce and secrete IL-10, which signals back to macrophages to polarize them to M2c to secrete TGFβ to mediate fibrosis.