Autoimmunity to ion channels in neurological diseases-Autoimmunity to aquaporin water channels

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune demyelinating disease in which the majority of patients have autoantibodies against the aquaporin4 (AQP4) water channel. In the central nervous system (CNS), AQP4 is expressed on the cell membrane of astrocytes, and anti-AQP4 antibodies harm AQP4 expressing astrocytes, resulting in astrocytopathy. The majority of patients are female and have acute visual disturbances and transverse myelitis, as well as brainstem and other cerebral lesions. These symptoms are frequently severe and develop quickly, resulting in substantial impairment in daily life. Patients are treated with high-dose methylprednisolone infusions, plasma exchange, and intravenous immunoglobulin administration during the acute stage. Based on the pathogenesis of NMOSD, various effective relapse-preventing therapies have emerged in recent years. The majority of them have been proved to have a positive impact on the patients who have been treated. They increased the number of therapy options available, albeit long-term efficacy and safety would need to be monitored for a longer period. Through its unique fluid transport function in the CNS, knowledge of the functions of AQP4 has grown in the field of not only inflammatory disorders like NMOSD, but also other neurodegenerative disorders like Alzheimer's disease.