MicroRNAs (miRNAs) play important roles in the regulation of immune responses. There is evidence that miRNAs also participate in the pathogenesis of multiple sclerosis (MS), but how the miRNAs regulate the pathogenesis of MS is still under investigation. The identification of new members of the miRNA family associated with the pathogenesis of MS could facilitate early diagnosis and treatment. Here we show that the level of miRNA let-7e is significantly upregulated in experimental autoimmune encephalomyelitis (EAE), an animal model of MS using miRNA array and quantitative real-time PCR. The expression of let-7e was mainly in CD4+ T cells and infiltrated mononuclear cells of central nervous system, and highly correlated with the development of EAE. We found that let-7e silencing in vivo inhibited encephalitogenic Th1 and Th17 cells and attenuated EAE, with reciprocal increase of Th2 cells; overexpression of let-7e enhanced Th1 and Th17 cells and aggravated EAE. We also identified IL-10 as one of the functional targets of let-7e. Together, we propose that let-7e is a new miRNA involved in the regulation of encephalitogenic T-cell differentiation and the pathogenesis of EAE.

Angelman syndrome (AS) is a neurogenetic disorder caused by loss of maternal UBE3A expression or mutation-induced dysfunction of its protein product, the E3 ubiquitin-protein ligase, UBE3A. In humans and rodents, UBE3A/Ube3a transcript is maternally imprinted in several brain regions, but the distribution of native UBE3A/Ube3a1 protein expression has not been comprehensively examined. To address this, we systematically evaluated Ube3a expression in the brain and peripheral tissues of wild-type (WT) and Ube3a maternal knockout mice (AS mice). Immunoblot and immunohistochemical analyses revealed a marked loss of Ube3a protein in hippocampus, hypothalamus, olfactory bulb, cerebral cortex, striatum, thalamus, midbrain, and cerebellum in AS mice relative to WT littermates. Also, Ube3a expression in heart and liver of AS mice showed greater than the predicted 50% reduction relative to WT mice. Co-localization 1 Throughout the manuscript, following the standard nomenclature, UBE3A and UBE3A will denote the human gene and protein name, respectively, and Ube3a and Ube3a the rodent gene and protein name, respectively. As indicated here, UBE3A and Ube3a are synonymous with E6-AP.

Summary The role of microRNA in the regulation of encephalitogenic T‐cell development is of interest in understanding the pathogenesis of multiple sclerosis (MS). Direct binding of microRNAs to their target mRNAs usually suppresses gene expression and facilitates mRNA degradation. In this study, we observed that the expression of several microRNAs was significantly altered in patients with MS. Interestingly, the expression of miR‐140‐5p, among other microRNAs, was significantly decreased in the peripheral blood mononuclear cells of patients with MS, and this microRNA may regulate encephalitogenic T helper type 1 (Th1) cell differentiation. The expression level of miR‐140‐5p was inversely correlated with disease severity with greater reduction in relapsing disease compared with remitting disease. Transfection of synthetic miR‐140‐5p in peripheral blood mononuclear cells suppressed encephalitogenic Th1 differentiation. Signal transducer and activator of transcription 1 (STAT1) was the functional target of miR‐140‐5p – transfection of the synthetic miR‐140‐5p suppressed activation of STAT1 and the expression of its downstream target, T‐bet. Our results suggested that miR‐140‐5p is probably involved in the regulation of encephalitogenic T cells in the pathogenesis of MS.

SummaryIdentification of biomarkers contributing to disease diagnosis, classification or prognosis could be of considerable utility. For example, primary methods to diagnose multiple sclerosis include magnetic resonance imaging and detection of immunologic abnormalities in cerebrospinal fluid. We determined if gene expression differences in blood discriminated MS subjects from comparator groups and identified panels of ratios that performed with varying degrees of accuracy depending upon complexity of comparator groups. High levels of overall accuracy were achieved by comparing MS to homogeneous comparator groups. Overall accuracy was compromised when MS was compared to a heterogeneous comparator group. Results, validated in independent cohorts, indicate that gene expression differences in blood accurately exclude or include a diagnosis of MS and suggest these approaches may provide clinically useful prediction of MS.

BackgroundDetection of brain lesions disseminated in space and time by magnetic resonance imaging remains a cornerstone for the diagnosis of clinically definite multiple sclerosis. We have sought to determine if gene expression biomarkers could contribute to the clinical diagnosis of multiple sclerosis.MethodsWe employed expression levels of 30 genes in blood from 199 subjects with multiple sclerosis, 203 subjects with other neurologic disorders, and 114 healthy control subjects to train ratioscore and support vector machine algorithms. Blood samples were obtained from 46 subjects coincident with clinically isolated syndrome who progressed to clinically definite multiple sclerosis determined by conventional methods. Gene expression levels from these subjects were inputted into ratioscore and support vector machine algorithms to determine if these methods also predicted that these subjects would develop multiple sclerosis. Standard calculations of sensitivity and specificity were employed to determine accuracy of these predictions.ResultsOur results demonstrate that ratioscore and support vector machine methods employing input gene transcript levels in blood can accurately identify subjects with clinically isolated syndrome that will progress to multiple sclerosis.ConclusionsWe conclude these approaches may be useful to predict progression from clinically isolated syndrome to multiple sclerosis.