CD274 and acute respiratory distress syndrome: To verify whether neutrophil PD-L1 regulated autophagy in ARDS, we confirmed that the neutrophil autophagosomes in BALF of ARDS PD-L1flox/flox mice were more than those of PD-L1WT/WT mice by electron microscopy, which implied that PD-L1-knockdown neutrophils had a higher level of autophagy (Figure 4E).