Experimental mouse model of optic neuritis with inflammatory demyelination produced by passive transfer of neuromyelitis optica-immunoglobulin G.
BACKGROUND
Although optic neuritis (ON) is a defining feature of neuromyelitis optica (NMO), appropriate animal models of NMO ON are lacking. Most NMO patients are seropositive for immunoglobulin G autoantibodies (NMO-IgG) against the astrocyte water channel aquaporin-4 (AQP4).


METHODS
Several approaches were tested to develop a robust, passive-transfer mouse model of NMO ON, including NMO-IgG and complement delivery by: (i) retrobulbar infusion; (ii) intravitreal injection; (iii) a single intracranial injection near the optic chiasm; and (iv) 3-days continuous intracranial infusion near the optic chiasm.


RESULTS
Little ON or retinal pathology was seen using approaches (i) to (iii). Using approach (iv), however, optic nerves showed characteristic NMO pathology, with loss of AQP4 and glial fibrillary acidic protein immunoreactivity, granulocyte and macrophage infiltration, deposition of activated complement, demyelination and axonal injury. Even more extensive pathology was created in mice lacking complement inhibitor protein CD59, or using a genetically modified NMO-IgG with enhanced complement effector function, including significant loss of retinal ganglion cells. In control studies, optic nerve pathology was absent in treated AQP4-deficient mice, or in wild-type mice receiving control (non-NMO) IgG and complement.


CONCLUSIONS
Passive transfer of NMO-IgG and complement by continuous infusion near the optic chiasm in mice is sufficient to produce ON with characteristic NMO pathology. The mouse model of NMO ON should be useful in further studies of NMO pathogenesis mechanisms and therapeutics.
Nithi
N
Asavapanumas
Julien
J
Ratelade
Marios C
MC
Papadopoulos
Jeffrey L
JL
Bennett
Marc H
MH
Levin
Department of Medicine and Physiology, University of California, 1246 Health Sciences East Tower, San Francisco, CA 94143-0521, USA. Alan.Verkman@ucsf.edu.
Alan S
AS
Verkman
D000818:Animals; D051401:Aquaporin 4 / Q000172:deficiency / Q000276:immunology*; D018957:CD59 Antigens / Q000235:genetics; D003711:Demyelinating Diseases / Q000209:etiology*; D004195:Disease Models, Animal; D007116:Immunization, Passive / Q000009:adverse effects*; D007074:Immunoglobulin G / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009471:Neuromyelitis Optica / Q000150:complications / Q000209:etiology / Q000276:immunology*; D009900:Optic Nerve / Q000276:immunology / Q000378:metabolism; D012160:Retina / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D012165:Retinal Ganglion Cells / Q000378:metabolism
C496031:Aqp4 protein, mouse; D051401:Aquaporin 4; D018957:CD59 Antigens; D007074:Immunoglobulin G