STAT1 and acute respiratory distress syndrome: Moreover, treatment with the JAK2 and STAT1 inhibitor effectively reduced the activation of JAK2-STAT1 signaling, downregulated PD-L1 expression on AMs in BALF from LPS-induced ALI mice and LPS-stimulated MH-S cells, and significantly improved the LPS-induced reduction in phagocytic activity in MH-S cells.