title: Semi-quantitative analyses of antibodies to N-methyl-d-aspartate type glutamate receptor subunits (GluN2B & GluN1) in the clinical course of Rasmussen syndrome.
abstract: OBJECTIVE
  In Rasmussen syndrome (RS), in addition to the predominant involvement of cytotoxic T cells, heterogeneous autoantibodies against neural molecules are also found, but their function has not been elucidated. We examined antibodies to N-methyl-d-aspartate (NMDA) type glutamate receptor (GluR) subunits (GluN2B & GluN1) semi-quantitatively in cerebrospinal fluid (CSF) samples from RS patients, and evaluated their changes over time and their roles in immunopathogenesis.
  
  
  METHODS
  Autoantibodies against N-terminal and C-terminal of GluN2B and GluN1 were examined in 40 CSF samples collected from 18 RS patients 5 to 180 months after the onset of RS. Epileptic patients without infectious etiology or progressive clinical course served as disease controls (n=23). Synthesized peptides encoding the extracellular and intracellular domains of human GluN2B and GluN1 subunits were used as antigens in ELISA. We defined the cut-off for these antibodies as mean +2 standard deviations (optimal density) of the disease controls. MRI were evaluated according to the MRI staging proposed by Bien et al. (2002b, Neurology 58, 250).
  
  
  RESULTS
  CSF levels of antibodies against N-terminal and C-terminal of GluN2B were higher in RS patients than in disease controls (p<0.01). Likewise, CSF levels of antibodies against N-terminal and C-terminal of GluN1 were also higher in RS patients than in disease controls (p<0.01). All four antibodies tested were below cut-off levels in almost all CSF samples collected within one year from epilepsy onset. The proportions of CSF samples with these antibodies above cut-off levels were highest from 12 to 23 months after epilepsy onset, and declined after 24 months. CSF levels of these antibodies were higher when seizure occurred daily than when seizure occurred less frequently (p<0.01), and were higher at MRI stage 3 than at MRI stages 0, 2 and 4 (p<0.05), except for anti-GluN1-CT antibody at stage 2.
  
  
  CONCLUSIONS
  Broad epitope recognition spectrum and delayed production of autoantibodies to NMDA type GluR in CSF of RS patients suggest that the autoantibodies are produced against NMDA type GluR antigens derived from cytotoxic T cell-mediated neuronal damages. These antibodies may impact the pathophysiology of RS in the most active stage, and could be a marker for active inflammation in the clinical course of RS. Further studies including passive transfer of the antibodies to mice may reveal the pivotal roles of the antibodies in RS.
authors.affiliation: National Epilepsy Center, Shizuoka Institute of Epilepsy and Neurological Disorders, Shizuoka, Japan. Electronic address: fukusukemyelin@gmail.com.
authors.forename: Tetsuhiro
authors.initials: T
authors.lastname: Fukuyama
authors.affiliation: National Epilepsy Center, Shizuoka Institute of Epilepsy and Neurological Disorders, Shizuoka, Japan; Department of Pediatrics, Gifu University School of Medicine, Yanagido, Gifu, Japan; School of Pharmaceutical Sciences, University Shizuoka, Shizuoka, Japan.
authors.forename: Yukitoshi
authors.initials: Y
authors.lastname: Takahashi
authors.affiliation: National Epilepsy Center, Shizuoka Institute of Epilepsy and Neurological Disorders, Shizuoka, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kubota
authors.affiliation: National Epilepsy Center, Shizuoka Institute of Epilepsy and Neurological Disorders, Shizuoka, Japan.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Mogami
authors.affiliation: National Epilepsy Center, Shizuoka Institute of Epilepsy and Neurological Disorders, Shizuoka, Japan.
authors.forename: Katsumi
authors.initials: K
authors.lastname: Imai
authors.affiliation: Department of Child Neurology, National Center Hospital, National Center of Neurology and Psychiatry (NCNP), Kodaira, Tokyo, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Kondo
authors.affiliation: Department of Child Neurology, National Center Hospital, National Center of Neurology and Psychiatry (NCNP), Kodaira, Tokyo, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sakuma
authors.affiliation: Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Tominaga
authors.affiliation: Department of Pediatrics, Tokyo Women's Medical University, Shinjuku-ku, Tokyo, Japan.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Oguni
authors.affiliation: National Epilepsy Center, Shizuoka Institute of Epilepsy and Neurological Disorders, Shizuoka, Japan.
authors.forename: Shigeko
authors.initials: S
authors.lastname: Nishimura
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000906:Antibodies / Q000032:analysis / Q000134:cerebrospinal fluid*; D002648:Child; D002675:Child, Preschool; D004660:Encephalitis / Q000134:cerebrospinal fluid* / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D009419:Nerve Tissue Proteins / Q000276:immunology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000276:immunology*; D018709:Statistics, Nonparametric; D013997:Time Factors; D055815:Young Adult
chemical_list: D000906:Antibodies; C485668:GRIN1 protein, human; C121001:NR2B NMDA receptor; D009419:Nerve Tissue Proteins; D016194:Receptors, N-Methyl-D-Aspartate
keywords: Antibodies; Cerebrospinal fluid; ELISA; NMDA type glutamate receptor; Rasmussen syndrome