title: Identification of novel autoantibodies to GABA(B) receptors in patients with neuropsychiatric systemic lupus erythematosus.
abstract: OBJECTIVE
  The gamma-aminobutyric acid type B receptors (GABAR(B)) are G-protein coupled receptors for GABA, the main inhibitory neurotransmitter in the brain. We identified GABAR(B) subunits as candidate antigens in patients with SLE using a random peptide display library. The aim of this study was to investigate the possible link between anti-GABAR(B) antibodies and disease activity and NPSLE.
  
  
  METHODS
  ELISA was performed with recombinant proteins of GABAR(B1b) and GABAR(B2) on serum samples from patients with SLE (n = 88), scleroderma (n = 20), myositis (n = 20) or vasculitis (n = 20) as well as healthy subjects (n = 20). Cerebrospinal fluid (CSF) from 23 patients with SLE was also examined.
  
  
  RESULTS
  Autoantibodies to GABAR(Bs) were exclusive to patients with SLE (P < 0.001) and positively associated with SLEDAI (anti-GABAR(B1b), P = 0.001; anti-GABAR(B2), P < 0.001). Of note, autoantibodies were positively linked with NPSLE (anti-GABAR(B1b), P = 0.02; anti-GABAR(B2), P = 0.03). Moreover, anti-GABAR(Bs) was detected in 61.5% of CSF samples from patients with active NPSLE, a frequency that was significantly higher than that for patients with non-SLE syndromes.
  
  
  CONCLUSIONS
  Anti-GABAR(B) antibodies could represent novel candidate markers for disease activity and NPSLE.
authors.affiliation: Division of Rheumatic Diseases, National Center for Global Health and Medicine and Department of Intractable Diseases, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan.Division of Rheumatic Diseases, National Center for Global Health and Medicine and Department of Intractable Diseases, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan. elephantscale@yahoo.co.jp.
authors.forename: Haruka
authors.initials: H
authors.lastname: Tsuchiya
authors.affiliation: Division of Rheumatic Diseases, National Center for Global Health and Medicine and Department of Intractable Diseases, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: Shiori
authors.initials: S
authors.lastname: Haga
authors.affiliation: Division of Rheumatic Diseases, National Center for Global Health and Medicine and Department of Intractable Diseases, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Takahashi
authors.affiliation: Division of Rheumatic Diseases, National Center for Global Health and Medicine and Department of Intractable Diseases, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Kano
authors.affiliation: Division of Rheumatic Diseases, National Center for Global Health and Medicine and Department of Intractable Diseases, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: Yukihito
authors.initials: Y
authors.lastname: Ishizaka
authors.affiliation: Division of Rheumatic Diseases, National Center for Global Health and Medicine and Department of Intractable Diseases, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: Akio
authors.initials: A
authors.lastname: Mimori
mesh_terms: D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000097:blood* / Q000134:cerebrospinal fluid; D015415:Biomarkers / Q000097:blood / Q000134:cerebrospinal fluid; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D020945:Lupus Vasculitis, Central Nervous System / Q000175:diagnosis* / Q000276:immunology / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D018080:Receptors, GABA-B / Q000276:immunology*; D012720:Severity of Illness Index
chemical_list: D001323:Autoantibodies; D015415:Biomarkers; D018080:Receptors, GABA-B
keywords: GABAB receptor; autoantibody; disease activity; neuropsychiatric systemic lupus erythematosus; systemic lupus erythematosus