Epidemiological, clinical, and immunological characteristics of neuromyelitis optica: A review

• Neuromyelitis optica (NMO) most commonly affects the optic nerves and spinal cord.
• The etiology of NMO involves interactions between genetic and environmental factors.
• Various autoimmune diseases have been reported in up to 30% of patients with neuromyelitis optica.
• Antibody against aquaporin 4 (anti-APQ4) is the major immunologic characteristic of NMO.
• Antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity mediate the damage processes.

The aim of this study was to review the epidemiological and clinical characteristics of neuromyelitis optica (NMO) and the immunopathological mechanisms involved in the neuronal damage. NMO is an inflammatory demyelinating autoimmune disease of the central nervous system that most commonly affects the optic nerves and spinal cord. NMO is thought to be more prevalent among non-Caucasians and where multiple sclerosis (MS) prevalence is low. NMO follows a relapsing course in more than 80–90% of cases, which is more commonly in women. It is a complex disease with an interaction between host genetic and environmental factors and the main immunological feature is the presence of anti-aquaporin 4 (AQP4) antibodies in a subset of patients. NMO is frequently associated with multiple other autoantibodies and there is a strong association between NMO with other systemic autoimmune diseases. AQP4-IgG can cause antibody-dependent cellular cytotoxicity (ADCC) when effector cells are present and complement-dependent cytotoxicity (CDC) when complement is present. Acute therapies, including corticosteroids and plasma exchange, are designed to minimize injury and accelerate recovery. Several aspects of NMO pathogenesis remain unclear. More advances in the understanding of NMO disease mechanisms are needed in order to identify more specific biomarkers to NMO diagnosis.