Orchestrating innate immune responses in multiple sclerosis: Molecular players

Innate immunity is the body's first line of defense against foreign pathogens. Although adaptive immune responses have for long time been considered to play important roles in the etiopathogenesis of autoimmune disorders such as multiple sclerosis (MS), evidence exists that adaptive immunity is not acting in isolation but rather in conjunction with components of the innate immune system. In fact, innate immune responses influence the nature of adaptive immune responses, and many components of innate immunity are used by adaptive immunity as effectors. In this review, we will focus on the role of key players of the innate immune system, including Toll-like receptors, the complement system and cytokines, on MS and its animal model, experimental autoimmune encephalomyelitis. We discuss in vitro and in vivo experimental data showing that the interaction mechanisms operating between adaptive and innate immune systems should be considered to better understand disease etiopathogenesis and the effect of therapies targeting components of the innate immune system.