Anti-MOG antibody: The history, clinical phenotype, and pathogenicity of a serum biomarker for demyelination

Myelin oligodendrocyte glycoprotein (MOG) is a protein exclusively expressed on the surface of oligodendrocytes and myelin in the central nervous system. MOG has been identified as a putative candidate autoantigen and autoantibody target in demyelination for almost three decades, with extensive literature validating its role in murine models of experimental autoimmune encephalomyelitis. Seminal studies using murine anti-MOG antibodies have highlighted the fact that antibodies that target epitopes of native MOG in its conformational state, rather than linearized or denature`d MOG, are biologically relevant. However, the relevance of anti-MOG antibodies in humans has been difficult to decipher over the years due to varying methods of detection as well as the fact that it was assumed that these antibodies would be clinically associated with multiple sclerosis. There is now international consensus that anti-MOG antibodies are important in both pediatric and adult demyelination, and the clinical association of MOG antibody-associated demyelination has been refined to include acute disseminated encephalomyelitis, relapsing and bilateral optic neuritis, and transverse myelitis. Anti-MOG antibodies are now thought not to be associated with multiple sclerosis in adults. Patients with MOG antibody-associated demyelination appear to have a unique clinical, radiological, and therapeutic profile, which represents a major advance in their diagnosis and management. It is imperative to understand whether anti-MOG antibodies are indeed pathogenic, and if so, their mechanisms of action. As it has become apparent that there are differences in MOG epitope binding between species, translation of animal studies to human demyelination should be analyzed in this context. Further work is required to identify the specific epitope binding sites in human disease and pathogenic mechanisms of anti-MOG antibodies, as well optimal therapeutic strategies to improve prognosis and minimize disability in these patients.