APOM and hydrops fetalis: ,16, 17, 18, 19, 20, 21, 22 The ApoM/S1P axis is a critical regulator of vascular inflammation and endothelial protection,3,16, 17, 18, 19,21, 22, 23, 24 and levels of ApoM/S1P have been inversely associated with outcomes in multiple inflammatory conditions including HF,25 T2DM,26 COVID-19,27 and sepsis.18