Experimental models of relapsing-remitting multiple sclerosis: Current concepts and perspective

Multiple sclerosis (MS) and its model experimental autoimmune encephalomyelitis (EAE) are debilitating paralytic diseases caused by inflammation, demyelination and axonal degeneration of the central nervous system (CNS). Whilst the autoimmune nature of MS is strongly suggested by evidence of myelin specific autoreactive T cells and antibodies, EAE is an experimentally induced CNS specific autoimmune disease. As opposed to the majority of MS patients, which exhibit a relapsing-remitting course of the disease, only a handful of available EAE models displays relapsing-remitting course. In this review, we will summarize differences in regulation of acute and relapsing disease with emphasis on relapsing-remitting EAE models, and outline advantages and limitations of available relapsing EAE models pertinent for studies of relapsing human disease. We will discuss current concepts of relapse regulation by focusing on immune and molecular mechanisms of neuroinflammation, oligodendrocyte damage, myelin loss and axonal degeneration. This review will compare our present understanding of relapse regulation in human versus experimental autoimmune disease. Translation of mechanisms learned from relapsing EAE into development of new therapies for MS will be evaluated. Finally, perspectives in further optimization and development of more suitable experimental models to study human relapsing-remitting MS will be discussed.