title: Ex vivo spinal cord slice model of neuromyelitis optica reveals novel immunopathogenic mechanisms.
abstract: OBJECTIVE
  Neuromyelitis optica (NMO) is a neuroinflammatory disease of spinal cord and optic nerve associated with serum autoantibodies (NMO-immunoglobulin G [IgG]) against astrocyte water channel aquaporin-4 (AQP4). Recent studies suggest that AQP4 autoantibodies are pathogenic. The objectives of this study were to establish an ex vivo spinal cord slice model in which NMO-IgG exposure produces lesions with characteristic NMO pathology, and to test the involvement of specific inflammatory cell types and soluble factors.
  
  
  METHODS
  Vibratome-cut transverse spinal cord slices were cultured on transwell porous supports. After 7 days in culture, spinal cord slices were exposed to NMO-IgG and complement for 1 to 3 days. In some studies inflammatory cells or factors were added. Slices were examined for glial fibrillary acidic protein (GFAP), AQP4, and myelin immunoreactivity.
  
  
  RESULTS
  Spinal cord cellular structure, including astrocytes, microglia, neurons, and myelin, was preserved in culture. NMO-IgG bound strongly to astrocytes in the spinal cord slices. Slices exposed to NMO-IgG and complement showed marked loss of GFAP, AQP4, and myelin. Lesions were not seen in the absence of complement or in spinal cord slices from AQP4 null mice. In cultures treated with submaximal NMO-IgG, the severity of NMO lesions was increased with inclusion of neutrophils, natural killer cells, or macrophages, or the soluble factors tumor necrosis factor α (TNFα), interleukin-6 (IL-6), IL-1β, or interferon-γ. Lesions were also produced in ex vivo optic nerve and hippocampal slice cultures.
  
  
  CONCLUSIONS
  These results provide evidence for AQP4, complement- and NMO-IgG-dependent NMO pathogenesis in spinal cord, and implicate the involvement of specific immune cells and cytokines. Our ex vivo model allows for direct manipulation of putative effectors of NMO disease pathogenesis in a disease-relevant tissue.
authors: Department of Physiology, University of California at San Francisco, San Francisco, CA 94143-0521, USA.
authors: Hua
authors: H
authors: Zhang
authors: Jeffrey L
authors: JL
authors: Bennett
authors: A S
authors: AS
authors: Verkman
mesh_terms: D000818:Animals; D051401:Aquaporin 4 / Q000172:deficiency / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000378:metabolism; D004195:Disease Models, Animal; D005786:Gene Expression Regulation / Q000187:drug effects; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D007074:Immunoglobulin G / Q000494:pharmacology; D051379:Mice; D018345:Mice, Knockout; D008840:Microfilament Proteins / Q000378:metabolism; D004676:Myelin Basic Protein / Q000378:metabolism; D009186:Myelin Sheath / Q000378:metabolism; D009471:Neuromyelitis Optica / Q000139:chemically induced / Q000235:genetics / Q000276:immunology* / Q000473:pathology*; D009900:Optic Nerve / Q000187:drug effects / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D009924:Organ Culture Techniques; D013116:Spinal Cord / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism* / Q000473:pathology; D014404:Tubulin / Q000378:metabolism
chemical_list: C491049:Aif1 protein, mouse; C496031:Aqp4 protein, mouse; D051401:Aquaporin 4; D002135:Calcium-Binding Proteins; D005904:Glial Fibrillary Acidic Protein; D007074:Immunoglobulin G; D008840:Microfilament Proteins; D004676:Myelin Basic Protein; D014404:Tubulin; C462941:beta3 tubulin, mouse