Ryanodine receptor‐dependent modulation of experimental autoimmune encephalomyelitis in mice

Abstract

Experimental autoimmune encephalomyelitis (EAE) in mice is an established animal model of T cell‐mediated autoimmune disease. Pathological changes seen in EAE represent a stereotypic response of the CNS tissues to immunological priming following damage. EAE induced by immunizing wild‐type (WT) C57BL/6 mice with myelin oligodendrocyte glycoprotein peptide 35–55 (MOG35–55) results in CNS inflammation (macrophages and CD3+ T lymphocytes), demyelination, and axonal loss, which causes progressive development of neurological symptoms and impairment of motor functions.The strength and duration of cytosolic calcium signals defines T cell activation, differentiation, and immune response. Our previous studies performed in T cell cultures clearly demonstrated physiological significance of ryanodine receptors (RyRs), the endoplasmic reticulum calcium release channels, in T cell calcium signaling in vitro (Thakur et al, 2012, J Biol Chem, 287: 37233–44). Here we report that treatment of activated human T cells with RyR blockers suppresses T cell proliferation and reduces frequencies of T cell subtypes secreting proinflammatory cytokines. Furthermore, manipulation of RyR activity in vivo significantly affects the course of the EAE in mice. EAE was induced by immunizing adult WT C57BL/6 mice and mice carrying gain‐of‐function RyR type 1 R163C mutation on C57BL/6 background strain (RyR1 R163C mice) with MOG35–55. We found that RyR1 R163C heterozygosity is associated with the earlier disease onset and augmentation of neurological symptoms compared with WT mice. These data indicate that a “leaky” RyR1 amplifies autoimmune response in mice. We also found that mice injected daily with RyR1 inhibitor dantrolene beginning at the time of EAE induction, displayed significantly fewer neurological symptoms, reduced CNS inflammatory infiltrate and less axon damage compared to control EAE mice injected with vehicle alone. Withdrawing the dantrolene on day 30 post‐immunization was immediately followed by the development of neurological symptoms. No pro‐inflammatory infiltrate and/or axonal damage were detected in EAE mice treated with dantrolene. These data underscoring the key role of RyR1 in mounting the normal and pathological immune responses and indicate that RyR1 represents a powerful new tool for modulation of autoimmune responses.