LDLR and acute respiratory distress syndrome: We found that re-ApoE3 exerted the positive protective impacts by promoting H3N2-induced M1 BMDMs toward M2 polarization and also enhanced the anti-inflammatory and antioxidant abilities of melatonin, indicating that melatonin-ApoE/LDLR axis may serve as a novel intervention signal for treating influenza A-induced ALI.