title: Fingolimod may support neuroprotection via blockade of astrocyte nitric oxide.
abstract: OBJECTIVE
  Although astrocytes participate in glial scar formation and tissue repair, dysregulation of the NFκB pathway and of nitric oxide (NO) production in these glia cells contributes to neuroinflammation and neurodegeneration. Here we investigated the role of the crosstalk between sphingosine-1-phosphate (S1P) and cytokine signaling cascades in astrocyte activation and inflammation-mediated neurodegeneration, and addressed the effects of fingolimod on astrocyte-neuron interaction and NO synthesis in vivo.
  
  
  METHODS
  Immunohistochemistry, immunofluorescence, and confocal microscopy were used to detect S1P receptors, interleukin (IL) 1R, IL17RA, and nitrosative stress in multiple sclerosis (MS) plaques, experimental autoimmune encephalomyelitis (EAE) spinal cord, and the spinal cord of fingolimod-treated EAE mice. An in vitro model was established to study the effects of S1P, IL1, and IL17 stimulation on NFkB translocation and NO production in astrocytes, on spinal neuron survival, and on astrocyte-neuron interaction. Furthermore, fingolimod efficacy in blocking astrocyte-mediated neurodegeneration was evaluated.
  
  
  RESULTS
  We found coordinated upregulation of IL1R, IL17RA, S1P1, and S1P3 together with nitrosative markers in astrocytes within MS and EAE lesions. In vitro studies revealed that S1P, IL17, and IL1 induced NFκB translocation and NO production in astrocytes, and astrocyte conditioned media triggered neuronal death. Importantly, fingolimod blocked the 2 activation events evoked in astrocytes by either S1P or inflammatory cytokines, resulting in inhibition of astrocyte-mediated neurodegeneration. Finally, therapeutic administration of fingolimod to EAE mice hampered astrocyte activation and NO production.
  
  
  CONCLUSIONS
  A neuroprotective effect of fingolimod in vivo may result from its inhibitory action on key astrocyte activation steps.
authors.affiliation: Institute of Experimental Neurology, Division of Neuroscience, San Raffaele Scientific Institute, Milan, Italy.
authors.forename: Emanuela
authors.initials: E
authors.lastname: Colombo
authors.forename: Marco
authors.initials: M
authors.lastname: Di Dario
authors.forename: Eleonora
authors.initials: E
authors.lastname: Capitolo
authors.forename: Linda
authors.initials: L
authors.lastname: Chaabane
authors.forename: Jia
authors.initials: J
authors.lastname: Newcombe
authors.forename: Gianvito
authors.initials: G
authors.lastname: Martino
authors.forename: Cinthia
authors.initials: C
authors.lastname: Farina
mesh_terms: D000368:Aged; D000818:Animals; D001253:Astrocytes / Q000187:drug effects* / Q000378:metabolism; D002478:Cells, Cultured; D054022:Cerebrum / Q000378:metabolism / Q000473:pathology; D004681:Encephalomyelitis, Autoimmune, Experimental / Q000188:drug therapy* / Q000276:immunology / Q000378:metabolism; D005260:Female; D000068876:Fingolimod Hydrochloride; D006801:Humans; D007166:Immunosuppressive Agents / Q000008:administration & dosage / Q000494:pharmacology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000188:drug therapy* / Q000276:immunology / Q000378:metabolism; D018696:Neuroprotective Agents / Q000008:administration & dosage / Q000494:pharmacology*; D009569:Nitric Oxide / Q000037:antagonists & inhibitors* / Q000096:biosynthesis; D011409:Propylene Glycols / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D053573:Receptors, Interleukin-1 Type I / Q000378:metabolism; D053722:Receptors, Interleukin-17 / Q000378:metabolism; D049349:Receptors, Lysosphingolipid / Q000378:metabolism; D015398:Signal Transduction; D013110:Sphingosine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism / Q000473:pathology
chemical_list: C109985:IL17RA protein, human; C508590:IL1R1 protein, human; D007166:Immunosuppressive Agents; D018696:Neuroprotective Agents; D011409:Propylene Glycols; D053573:Receptors, Interleukin-1 Type I; D053722:Receptors, Interleukin-17; D049349:Receptors, Lysosphingolipid; D009569:Nitric Oxide; D000068876:Fingolimod Hydrochloride; D013110:Sphingosine