Interleukin 17 (IL-17)-producing T helper cells (T(H)-17 cells) are increasingly recognized as key participants in various autoimmune diseases, including multiple sclerosis. Although sets of transcription factors and cytokines are known to regulate T(H)-17 differentiation, the role of noncoding RNA is poorly understood. Here we identify a T(H)-17 cell-associated microRNA, miR-326, whose expression was highly correlated with disease severity in patients with multiple sclerosis and mice with experimental autoimmune encephalomyelitis (EAE). In vivo silencing of miR-326 resulted in fewer T(H)-17 cells and mild EAE, and its overexpression led to more T(H)-17 cells and severe EAE. We also found that miR-326 promoted T(H)-17 differentiation by targeting Ets-1, a negative regulator of T(H)-17 differentiation. Our data show a critical role for microRNA in T(H)-17 differentiation and the pathogenesis of multiple sclerosis.

Multiple sclerosis (MS) is a devastating neuroinflammatory disorder of the central nervous system (CNS) in which T cells that are reactive with major components of myelin sheaths have a central role. The receptor for advanced glycation end products (RAGE) is present on T cells, mononuclear phagocytes and endothelium. Its pro-inflammatory ligands, S100-calgranulins, are upregulated in MS and in the related rodent model, experimental autoimmune encephalomyelitis (EAE). Blockade of RAGE suppressed EAE when disease was induced by myelin basic protein (MBP) peptide or encephalitogenic T cells, or when EAE occurred spontaneously in T-cell receptor (TCR)-transgenic mice devoid of endogenous TCR-alpha and TCR-beta chains. Inhibition of RAGE markedly decreased infiltration of the CNS by immune and inflammatory cells. Transgenic mice with targeted overexpression of dominant-negative RAGE in CD4+ T cells were resistant to MBP-induced EAE. These data reinforce the importance of RAGE-ligand interactions in modulating properties of CD4+ T cells that infiltrate the CNS.

Xu et al. show that LRCH1 interferes with the GEF activity of DOCK8 to inhibit Cdc42 activation. Upon chemokine stimulation, DOCK8 is phosphorylated and released from LRCH1 to drive cell migration. LRCH1 overexpression reduces CD4+ T cell migration to the CNS and ameliorates experimental autoimmune encephalomyelitis.

No abstract