S1PR1 and acute respiratory distress syndrome: Lipopolysaccharide (LPS)-induced vascular leak is more potent in SphK1 knockout mice than in wild-type mice [129], and an intratracheal or intravenous administration of S1P or SEW-2871, an agonist of S1P1, reduces endothelial barrier dysfunction in murine models of LPS-induced ARDS, whereas SB-649146, an antagonist of S1P1, reverses this effect of SEW-2871 [130].