title: Sphingosine-1-phosphate/sphingosine-1-phosphate receptor 1 signaling is required for migration of naive human T cells from the thymus to the periphery.
abstract: The mechanisms that govern the egress of mature thymocytes from the human thymus to the periphery remain understudied yet are of utmost importance to the field of basic immunology, as well as T-cell reconstitution in various immunodeficiencies. We examined the expression and function of sphingosine-1-phosphate (S1P) receptors in human thymocyte egress.
  
  
  
  We aimed to determine whether S1P receptors (S1P-Rs) play a role in mature human thymocyte egress and to identify the thymocyte population or populations that express S1P-Rs and respond to S1P by migrating across a concentration gradient.
  
  
  
  Human thymocytes were exposed to S1P in Transwell plate migration assays coupled to flow cytometry to evaluate the response to S1P of thymocytes at different stages of maturation. Constitutive S1P-R expression was quantified by means of real-time PCR in sorted thymocyte subsets and flow cytometry. S1P-R1 and Kruppel-like factor 2 expression were monitored after S1P exposure by using flow cytometry and quantitative PCR.
  
  
  
  S1P-R1 was the prevalent S1P receptor on mature human thymocytes (CD3(hi)CD27(+)CD69(-)), the population that also demonstrated the greatest response to S1P in migration assays. Pretreatment with FTY720, an S1P-R1 nonselective modulator significantly reduced migration and suggested a role for S1P-R2 in retaining thymocytes in the tissue. Lastly, surface S1P-R1 expression, as well S1PR1 and Kruppel-like factor 2 (KLF2) transcripts, were significantly decreased in mature thymocytes on exposure to S1P.
  
  
  
  Mature human thymocytes rely on S1P-R1 to migrate toward S1P. Taken in the context of murine work demonstrating that S1P is required for thymocyte egress to the periphery, our data highlight a new key chemokine for human thymocyte egress.
authors.affiliation: Department of Microbiology, Immunology and Molecular Genetics, University of California Los Angeles, Los Angeles, Calif; UCLA AIDS Institute, David Geffen School of Medicine at UCLA, University of California, Los Angeles, Calif.
authors.forename: Rachel S
authors.initials: RS
authors.lastname: Resop
authors.affiliation: Department of Microbiology, Immunology and Molecular Genetics, University of California Los Angeles, Los Angeles, Calif.
authors.forename: Marc
authors.initials: M
authors.lastname: Douaisi
authors.affiliation: Department of Microbiology, Immunology and Molecular Genetics, University of California Los Angeles, Los Angeles, Calif.
authors.forename: Joshua
authors.initials: J
authors.lastname: Craft
authors.affiliation: Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Loes C M
authors.initials: LC
authors.lastname: Jachimowski
authors.affiliation: Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Bianca
authors.initials: B
authors.lastname: Blom
authors.affiliation: Department of Microbiology, Immunology and Molecular Genetics, University of California Los Angeles, Los Angeles, Calif; Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; UCLA AIDS Institute, David Geffen School of Medicine at UCLA, University of California, Los Angeles, Calif; Department of Pediatrics, University of California Los Angeles, Amsterdam, The Netherlands. Electronic address: uittenbo@ucla.edu.
authors.forename: Christel H
authors.initials: CH
authors.lastname: Uittenbogaart
mesh_terms: D015415:Biomarkers; D002465:Cell Movement / Q000276:immunology*; D002633:Chemotaxis / Q000276:immunology; D015870:Gene Expression; D006801:Humans; D016130:Immunophenotyping; D008246:Lysophospholipids / Q000378:metabolism*; D010641:Phenotype; D049349:Receptors, Lysosphingolipid / Q000378:metabolism*; D015398:Signal Transduction; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D060168:Thymocytes / Q000276:immunology / Q000378:metabolism; D013950:Thymus Gland / Q000276:immunology* / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D008246:Lysophospholipids; D049349:Receptors, Lysosphingolipid; C060506:sphingosine 1-phosphate; D013110:Sphingosine
keywords: S1P-R1; S1P-R2; Sphingosine-1-phosphate; T-cell reconstitution; human immunology; migration; thymic egress; thymus