title: FTY720 impairs CD8 T-cell function independently of the sphingosine-1-phosphate pathway.
abstract: Fingolimod (FTY720) is a multiple sclerosis (MS) therapeutic that upon phosphorylation causes the internalization of sphingosine-1-phosphate receptors (S1PR) and traps CCR7+ T-cells in lymph nodes but relatively spares CCR7-effector T-cells. Nonetheless, FTY720-treated patients are more susceptible to viral infections, indicating a CD8 T-cell defect. Thus, the effects of FTY720 on CD8 T-cells were investigated. To this end, we utilized experimental autoimmune encephalomyelitis (EAE) and a murine influenza model. CD8 T-cell trafficking, IFNγ and Granzyme B (GrB) production were assessed by flow cytometry. CD8 T-cell cytotoxic function was assessed in vitro by an LDH release assay. FTY720 not only ameliorated EAE by sequestering T-cells, but also reduced IFNγ and Granzyme B (GrB) in splenic CD8 T-cells. Murine influenza infection was exacerbated and mortality was increased, as FTY720 inhibited CD8 T-cell GrB production and lung infiltration. Remarkably, only the unphosphorylated compound was able to reduce IFNγ and GrB levels in CD8 T-cells and inhibits their cytotoxic function in vitro. The phosphorylated moiety had no effect in vitro, indicating that CD8 T-cell suppression by FTY720 is independent of S1PR modulation. The addition of arachidonic acid rescued CD8 T-cell function, suggesting that this effect may be mediated via inhibition of cytosolic phospholipase A2. Herein, we demonstrate that FTY720 suppresses CD8 T-cells independently of its trafficking effects and S1PR modulation. This provides a novel explanation not only for the increased rate of viral infections in FTY720-treated patients, but also for its efficacy in MS, as CD8 T-cells have emerged as crucial mediators of MS pathogenesis.
authors.affiliation: Department of Neurology, Johns Hopkins University School of Medicine, 600 N. Wolfe St., Baltimore, MD 21287, USA.
authors.forename: Achilles
authors.initials: A
authors.lastname: Ntranos
authors.affiliation: W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe St., Baltimore, MD 21205, USA.
authors.forename: Olivia
authors.initials: O
authors.lastname: Hall
authors.affiliation: W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe St., Baltimore, MD 21205, USA.
authors.forename: Dionne P
authors.initials: DP
authors.lastname: Robinson
authors.affiliation: Department of Neurology, Johns Hopkins University School of Medicine, 600 N. Wolfe St., Baltimore, MD 21287, USA.
authors.forename: Inna V
authors.initials: IV
authors.lastname: Grishkan
authors.affiliation: Department of Neurology, Johns Hopkins University School of Medicine, 600 N. Wolfe St., Baltimore, MD 21287, USA.
authors.forename: Jason T
authors.initials: JT
authors.lastname: Schott
authors.affiliation: Department of Neurology, Johns Hopkins University School of Medicine, 600 N. Wolfe St., Baltimore, MD 21287, USA.
authors.forename: Dominique M
authors.initials: DM
authors.lastname: Tosi
authors.affiliation: W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe St., Baltimore, MD 21205, USA.
authors.forename: Sabra L
authors.initials: SL
authors.lastname: Klein
authors.affiliation: Department of Neurology, Johns Hopkins University School of Medicine, 600 N. Wolfe St., Baltimore, MD 21287, USA. Electronic address: pcalabr1@jhmi.edu.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Calabresi
authors.affiliation: Department of Neurology, Johns Hopkins University School of Medicine, 600 N. Wolfe St., Baltimore, MD 21287, USA. Electronic address: agocke4@jhu.edu.
authors.forename: Anne R
authors.initials: AR
authors.lastname: Gocke
mesh_terms: D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects* / Q000276:immunology; D002634:Chemotaxis, Leukocyte / Q000187:drug effects; D004681:Encephalomyelitis, Autoimmune, Experimental / Q000276:immunology*; D005260:Female; D000068876:Fingolimod Hydrochloride; D005434:Flow Cytometry; D053804:Granzymes / Q000096:biosynthesis; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D053118:Influenza A Virus, H1N1 Subtype; D007371:Interferon-gamma / Q000096:biosynthesis; D008246:Lysophospholipids / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009976:Orthomyxoviridae Infections / Q000276:immunology*; D011409:Propylene Glycols / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology
chemical_list: D007166:Immunosuppressive Agents; D008246:Lysophospholipids; D011409:Propylene Glycols; C060506:sphingosine 1-phosphate; D007371:Interferon-gamma; D053804:Granzymes; D000068876:Fingolimod Hydrochloride; D013110:Sphingosine
keywords: Autoimmunity; CD8+ T cells; Experimental autoimmune encephalomyelitis (EAE); Fingolimod (FTY720); Murine influenza; Viral infection