title: Intrathecal pathogenic anti-aquaporin-4 antibodies in early neuromyelitis optica.
abstract: OBJECTIVE
  The serum of most neuromyelitis optica (NMO) patients contains autoantibodies (NMO-IgGs) directed against the aquaporin-4 (AQP4) water channel located on astrocyte foot processes in the perivessel and subpial areas of the brain. Our objectives were to determine the source of central nervous system (CNS) NMO-IgGs and their role in disease pathogenesis.
  
  
  METHODS
  Fluorescence-activated cell sorting and single-cell reverse transcriptase polymerase chain reaction were used to identify overrepresented plasma cell immunoglobulin (Ig) sequences in the cerebrospinal fluid (CSF) of an NMO patient after a first clinical attack. Monoclonal recombinant antibodies (rAbs) were generated from the paired heavy and light chain sequences and tested for target specificity and Fc effector function. The effect of CSF rAbs on CNS immunopathology was investigated by delivering single rAbs to rats with experimental autoimmune encephalomyelitis (EAE).
  
  
  RESULTS
  Repertoire analysis revealed a dynamic, clonally expanded plasma cell population with features of an antigen-targeted response. Using multiple independent assays, 6 of 11 rAbs generated from CSF plasma cell clones specifically bound to AQP4. AQP4-specific rAbs recognized conformational epitopes and mediated both AQP4-directed antibody-dependent cellular cytotoxicity and complement-mediated lysis. When administered to rats with EAE, an AQP4-specific NMO CSF rAb induced NMO immunopathology: perivascular astrocyte depletion, myelinolysis, and complement and Ig deposition.
  
  
  CONCLUSIONS
  Molecular characterization of the CSF plasma cell repertoire in an early NMO patient demonstrates that AQP4-specific Ig is synthesized intrathecally at disease onset and directly contributes to CNS pathology. AQP4 is now the first confirmed antigenic target in human demyelinating disease.
authors: Department of Neurology and Ophthalmology, University of Colorado Denver School of Medicine, Aurora, CO 80045, USA. jeffrey.bennett@ucdenver.edu
authors: Jeffrey L
authors: JL
authors: Bennett
authors: Chiwah
authors: C
authors: Lam
authors: Sudhakar Reddy
authors: SR
authors: Kalluri
authors: Philippe
authors: P
authors: Saikali
authors: Katherine
authors: K
authors: Bautista
authors: Cecily
authors: C
authors: Dupree
authors: Magdalena
authors: M
authors: Glogowska
authors: David
authors: D
authors: Case
authors: Jack P
authors: JP
authors: Antel
authors: Gregory P
authors: GP
authors: Owens
authors: Don
authors: D
authors: Gilden
authors: Stefan
authors: S
authors: Nessler
authors: Christine
authors: C
authors: Stadelmann
authors: Bernhard
authors: B
authors: Hemmer
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D051401:Aquaporin 4 / Q000134:cerebrospinal fluid* / Q000235:genetics / Q000276:immunology*; D001323:Autoantibodies / Q000134:cerebrospinal fluid*; D015415:Biomarkers / Q000134:cerebrospinal fluid; D002460:Cell Line; D002478:Cells, Cultured; D005260:Female; D005333:Fetus; D006801:Humans; D007074:Immunoglobulin G / Q000134:cerebrospinal fluid; D051379:Mice; D008875:Middle Aged; D008969:Molecular Sequence Data; D009471:Neuromyelitis Optica / Q000134:cerebrospinal fluid* / Q000175:diagnosis*; D051381:Rats; D011917:Rats, Inbred Lew; D013129:Spinal Puncture; D013997:Time Factors
chemical_list: D051401:Aquaporin 4; D001323:Autoantibodies; D015415:Biomarkers; D007074:Immunoglobulin G