Immunomodulator FTY720 Induces eNOS-Dependent Arterial Vasodilatation via the Lysophospholipid Receptor S1P 3

Abstract
The novel immunomodulator FTY720 is effective in experimental models of transplantation and autoimmunity, and is currently undergoing Phase III clinical trials for prevention of kidney graft rejection. FTY720 is a structural analogue of sphingosine-1-phosphate (S1P) and activates several of the S1P receptors. We show that FTY720 induces endothelium-dependent arterial vasodilation in phenylephrine precontracted mouse aortae. Vasodilation did not occur in thoracic aortic rings from eNOS-deficient mice, implicating and effect dependent of activation of the eNOS/NO pathway. Accordingly, FTY720 induced NO release, Akt-dependent eNOS phosphorylation and activation in human endothelial cells. For biological efficacy, FTY720 required endogenous phosphorylation, since addition of the sphingosine kinase antagonist N′,N-dimethylsphingosine (DMS) prevented activation of eNOS in vitro and inhibited vasodilation in isolated arteries. The endothelial phosphorylation of FTY720 was extremely rapid with almost complete con...

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