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Diabetes. 2008 Feb;57(2):484-93. Epub 2007 Nov 14.

Sphingosine-1-phosphate reduces CD4+ T-cell activation in type 1 diabetes through regulation of hypoxia-inducible factor short isoform I.1 and CD69.

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  • 1Cardiovascular Research Center, University of Virginia, P.O. Box 801394, 415 Lane Rd., MR5, Rm. G123, Charlottesville, VA 22908, USA.

Abstract

OBJECTIVES:

Non-obese diabetic (NOD) mice develop spontaneous type 1 diabetes. We have shown that sphingosine-1-phosphate (S1P) reduces activation of NOD diabetic endothelium via the S1P1 receptor. In the current study, we tested the hypothesis that S1P could inhibit CD4(+) T-cell activation, further reducing inflammatory events associated with diabetes.

RESEARCH DESIGN AND METHODS:

CD4(+) T-cells were isolated from diabetic and nondiabetic NOD mouse splenocytes and treated in the absence or presence of S1P or the S1P1 receptor-specific agonist, SEW2871. Lymphocyte activation was examined using flow cytometry, cytokine bead assays, and a lymphocyte:endothelial adhesion assay.

RESULTS:

Diabetic T-cells secreted twofold more gamma-interferon (IFN-gamma) and interleukin-17 than nondiabetic lymphocytes. Pretreatment with either S1P or SEW2871 significantly reduced cytokine secretion by approximately 50%. Flow cytometry analysis showed increased expression of CD69, a marker of lymphocyte activation, on diabetic T-cells. Both S1P and SEW2871 prevented upregulation of CD69 on CD4(+) cells. Quantitative RT-PCR showed that lymphocytes from diabetic NOD mice had 2.5-fold lower hypoxia-inducible factor (HIF)-1alpha short isoform I.1 (HIF1alphaI.1) mRNA levels than control. HIF1alphaI.1 is a negative regulator of lymphocyte activation. S1P significantly increased HIF1alpha I.1 mRNA levels in both control and diabetic groups. IFN-gamma production and surface CD69 expression was significantly increased in lymphocytes of HIF1alphaI.1-deficient mice. S1P did not reduce either CD69 or IFN-gamma expression in lymphocytes from HIF1alphaI.1-deficient mice.

CONCLUSIONS:

S1P acts through the S1P1 receptor and HIF1alpha I.1 to negatively regulate T-cell activation, providing a potential therapeutic target for prevention of diabetes and its vascular complications.

[PubMed - indexed for MEDLINE]
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