MPO and acute respiratory distress syndrome: Anti-Ly6G antibody and PAD4 inhibitor CI-amidine, known to deplete neutrophils, were also found to significantly inhibit NETs levels in ARDS mice as indicated by reduced serum levels of cell-free DNA (Supplementary Figure 1A), MPO (Supplementary Figure 1B), and MPO-DNA complexes (Supplementary Figure 1C) as well as reduced expression of CitH3 in lung tissues of ARDS mice after treatment (Supplementary Figure 1D).