title: Interleukin-1β causes synaptic hyperexcitability in multiple sclerosis.
abstract: OBJECTIVE
  The frequency of inflammatory episodes in the early stages of multiple sclerosis (MS) has been correlated with late neurodegeneration, but the mechanism by which inflammation gives rise to delayed neuronal damage is unknown. Increased activity of the neurotransmitter glutamate is thought to play a role in the inflammation-driven neurodegenerative process of MS, and therefore we tested whether inflammatory cytokines released during acute MS attacks have the property of enhancing glutamate-mediated transmission and excitotoxicity in central neurons.
  
  
  METHODS
  We compared the effect of cerebrospinal fluid (CSF) from active and quiescent MS patients on glutamate-mediated excitatory postsynaptic currents (EPSCs) and excitotoxic damage in rodent brain slices. We also measured CSF concentrations of tumor necrosis factor-α, of interleukin-1β (IL-1β), and of IL-1 receptor antagonist (IL-1ra), and correlated cytokine levels with cortical excitability assessed in MS patients by means of paired-pulse transcranial magnetic stimulation (TMS).
  
  
  RESULTS
  CSF from MS patients with enhanced brain lesions at magnetic resonance imaging was able to increase spontaneous EPSC frequency and glutamate-mediated neuronal swelling in vitro, through a mechanism dependent on enhanced IL-1β signaling and increased glutamate α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor stimulation. Furthermore, IL-1β/IL-1ra ratio was significantly higher in the CSF of active MS subjects, and correlated with intracortical facilitation, an accredited TMS measure of glutamate transmission. Finally, we identified for the first time transient receptor potential vanilloid 1 channels as essential intermediates for the synaptic action of IL-1β on central glutamatergic synapses.
  
  
  CONCLUSIONS
  Our results provide compelling evidence of the synaptic mechanism linking inflammation and excitotoxic neurodegeneration in MS.
authors.affiliation: Neurological Clinic, Department of Neuroscience, Tor Vergata University, Rome, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Rossi
authors.forename: Roberto
authors.initials: R
authors.lastname: Furlan
authors.forename: Valentina
authors.initials: V
authors.lastname: De Chiara
authors.forename: Caterina
authors.initials: C
authors.lastname: Motta
authors.forename: Valeria
authors.initials: V
authors.lastname: Studer
authors.forename: Francesco
authors.initials: F
authors.lastname: Mori
authors.forename: Alessandra
authors.initials: A
authors.lastname: Musella
authors.forename: Alessandra
authors.initials: A
authors.lastname: Bergami
authors.forename: Luca
authors.initials: L
authors.lastname: Muzio
authors.forename: Giorgio
authors.initials: G
authors.lastname: Bernardi
authors.forename: Luca
authors.initials: L
authors.lastname: Battistini
authors.forename: Gianvito
authors.initials: G
authors.lastname: Martino
authors.forename: Diego
authors.initials: D
authors.lastname: Centonze
mesh_terms: D000328:Adult; D000818:Animals; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D053583:Interleukin-1beta / Q000009:adverse effects / Q000134:cerebrospinal fluid / Q000502:physiology*; D008297:Male; D051379:Mice; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000134:cerebrospinal fluid / Q000473:pathology / Q000503:physiopathology*; D009924:Organ Culture Techniques; D013569:Synapses / Q000502:physiology; D009435:Synaptic Transmission / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation / Q000379:methods; D055815:Young Adult
chemical_list: D053583:Interleukin-1beta