HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: db07-0855v1 57/2/484    most recent Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Srinivasan, S. Articles by Hedrick, C. C. Search for Related Content PubMed PubMed Citation Articles by Srinivasan, S. Articles by Hedrick, C. C. Social Bookmarking                What's this?

Sphingosine-1-Phosphate Reduces CD4⁺ T-Cell Activation in Type 1 Diabetes Through Regulation of Hypoxia-Inducible Factor Short Isoform I.1 and CD69

¹ Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia
² New England Inflammation and Tissue Protection Institute, Northeastern University, Boston, Massachusetts
³ Department of Pharmacology, University of Virginia, Charlottesville, Virginia

Address correspondence and reprint requests to Catherine C. Hedrick, PhD, Cardiovascular Research Center, University of Virginia, P.O. Box 801394, 415 Lane Rd., MR5, Rm. G123, Charlottesville, VA 22908. E-mail: cch6n{at}virginia.edu

Abbreviations: ELISA, enzyme-linked immunosorbent assay; FACS, fluorescence-activated cell sorting; FITC, fluorescein isothiocyanate; HIF, hypoxia-inducible factor; HIFBS, heat-inactivated fetal bovine serum; IFN-, -interferon; IL, interleukin; mAb, monoclonal antibody; S1P, sphingosine-1-phosphate; TCR, T-cell receptor; TNF-, tumor necrosis factor-; UVA, University of Virginia

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 -interferon (IFN-) and interleukin-17 than nondiabetic lymphocytes. Pretreatment with either S1P or SEW2871 significantly reduced cytokine secretion by 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)-1 short isoform I.1 (HIF1I.1) mRNA levels than control. HIF1I.1 is a negative regulator of lymphocyte activation. S1P significantly increased HIF1 I.1 mRNA levels in both control and diabetic groups. IFN- production and surface CD69 expression was significantly increased in lymphocytes of HIF1I.1-deficient mice. S1P did not reduce either CD69 or IFN- expression in lymphocytes from HIF1I.1-deficient mice.

CONCLUSIONS—S1P acts through the S1P1 receptor and HIF1 I.1 to negatively regulate T-cell activation, providing a potential therapeutic target for prevention of diabetes and its vascular complications.

CiteULike    Del.icio.us    Digg    Reddit    Technorati    What's this?