Update on the etiology and pathogenesis of multiple sclerosis and neuromyelitis optica

Recent findings on the etiology and pathogenesis of multiple sclerosis (MS) and neuromyelitis optica (NMO) were reviewed. As new MS-susceptibility genes, IL-7Ralpha and IL-2Ralpha genes were identified. Among environmental factors, Epstein-Barr virus, vitamin D and smoking appear to play a role in developing MS. As opposed to previous reports on the lesion heterogeneity, a recent study showed antibody-, complement-mediated myelin phagocytosis is the dominant mechanism of demyelination in MS. Clinical trials of monoclonal antibodies demonstrated that targeting such immune molecules as CD52, CD25, VLA-4 and CD20, is therapeutically effective. Aquaporin-4 (AQP4) antibody is a diagnostically useful biomarker of NMO, and a recent study revealed severe astrocytic damage in NMO probably caused by AQP4-targeting is a pathological finding distinct from that in MS.