The pathogenic role of miR-92a in the regulation of T helper cell responses in EAE and MS

项目摘要/摘要 MicroRNAs是多发性硬化症(MS)发病机制中的关键基因表达调控因子 及其动物模型，实验性自身免疫性脑脊髓炎(EAE)。然而，特定的miRNA途径 将临床活动与EAE和MS的致病和调节免疫机制直接联系起来 目前仍不清楚。最近，我们发现了一种与临床相关的miRNA，miR-92a，它的表达水平很高 多发性硬化症患者升高，与临床疾病活动性和病理免疫密切相关 具体来说，我们的数据表明miR-92a通过抑制中枢神经系统炎症而促进中枢神经系统炎症 Tregs和促进Th17和Th1效应器功能。MIR-92a在EAE中水平升高，而miR-92a 损失显著地减弱了EAE。这种衰减与Treg增加和Th17减少有关 减少Th1/Th17致病效应分子，尤其是GM-CSF。从机械上讲， MIR-92a似乎通过直接靶向Foxo1来抑制Treg的分化、稳定性和抑制功能。 MIR-92a还通过调节Foxo1促进Th17的发育。在非致病性Th17细胞中，miR-92a 抑制Foxo1使RORgt从Foxo1介导的抑制中解脱出来，进而上调Th17 转录程序。在致病Th17细胞中，靶向Foxo1的miR-92a减轻IL-23R和IL-1R Foxo1介导的抑制作用。这会增强对IL-23和IL-1b以及GM-CSF的反应性 制作。在Th1细胞中，miR-92a对初始分化是必不可少的，但也通过以下方式促进GM-CSF 目标是Foxo1。因此，T细胞特异性的miR-92a的缺失足以减弱EAE，并且miR-92a- 92a抑制剂治疗可有效改善EAE。与小鼠类似，miR-92a抑制Tregs，而 在人类体内促进Th17的发育。最重要的是，多发性硬化症患者血清中miR-92a增加， 在多个临床参数上与疾病相关，包括神经症状和脑萎缩。 我们还发现MS CD4+T细胞中miR-92a的表达增加，这与Treg/Th17标记的改变有关 在MS中，这些发现表明，介导EAE的致病miR-92a途径也可能 调节MS的发病机制。因此，我们将检验我们的假设，即miR-92a促进神经炎症 在EAE和MS中，通过两种相互关联的机制：1)抑制Treg的发育和功能；2) 促进致病Th17/Th1效应器功能。在目标1中，我们将通过以下方式来研究分子机制 哪个miR-92a控制EAE中调节性和炎性T细胞的平衡并测试治疗 在临床相关的EAE模型中沉默miR-92a的疗效。在目标2中，我们将在人类身上研究 MiR-92a控制调节性和炎性T细胞发育的分子机制 还要研究miR-92a作为生物标志物，以及miR-92a在MS和MS患者T细胞中的功能。MIR-92a是独一无二的 在EAE/MS中，它构成了调节多个T细胞通路的单个靶点，因此具有重要意义。 将有助于导航MS中关键的miR-92a相关机制，这可能是新的治疗途径的基础。

Project Summary/Abstract MicroRNAs are critical gene expression regulators implicated in the pathogenesis of multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE). However, specific miRNA pathways that directly connect clinical activity with pathogenic and regulatory immune mechanisms in EAE and MS remains unclear. Recently, we identified a clinically relevant miRNA, miR-92a, whose expression is highly increased in MS patients and strongly associated with clinical disease activity and pathological immune mechanisms in EAE and MS. Specifically, our data suggest miR-92a promotes CNS inflammation by inhibiting Tregs and promoting Th17 and Th1 effector functions. MiR-92a levels are increased in EAE, and that miR-92a loss strikingly attenuates EAE. This attenuation is associated with increased Treg and decreased Th17 frequency, as well as decreased Th1/Th17 pathogenic effector molecules, notably GM-CSF. Mechanistically, miR-92a appears to inhibit Treg differentiation, stability, and suppressive function by directly targeting Foxo1. MiR-92a also promotes Th17 development by modulating Foxo1. In non-pathogenic Th17 cells, miR-92a inhibition of Foxo1 relieves RORgt from Foxo1-mediated inhibition, which in turn upregulates the Th17 transcriptional program. In pathogenic Th17 cells, miR-92a targeting of Foxo1 relieves IL-23R and IL-1R from Foxo1-mediated inhibition. This then enhances responsiveness to IL-23 and IL-1b, as well as GM-CSF production. In Th1 cells, miR-92a is dispensable for initial differentiation, but also promotes GM-CSF by targeting the Foxo1. Accordingly, T cell-specific deletion of miR-92a is sufficient to attenuate EAE, and miR- 92a inhibitor therapeutic effectively ameliorates EAE. Analogous to mice, miR-92a inhibits Tregs, while promoting Th17 development, in humans. Most importantly, miR-92a is increased in MS patient sera, which correlates with disease across multiple clinical parameters, including neurological symptoms and brain atrophy. We also show an increase in miR-92a in MS CD4+ T cells, which is associated with altered Treg/Th17 markers in MS. These findings suggest the pathogenic miR-92a-mediated pathways that mediate EAE may also modulate MS pathogenesis. Therefore, we will test our hypothesis that miR-92a promotes neuroinflammation in EAE and MS by two interlinked mechanisms: 1) inhibiting the development and function of Tregs; and 2) promoting pathogenic Th17/Th1 effector functions. In Aim 1, we will investigate the molecular mechanisms by which miR-92a control the balance of regulatory and inflammatory T cells in EAE and test the therapeutic efficacy of silencing miR-92a in clinically relevant EAE models. In Aim 2, we will investigate in humans the molecular mechanisms by which miR-92a controls the development of regulatory and inflammatory T cells and also study miR-92a as a biomarker, and miR-92a function, in MS and MS patient T cells. MiR-92a is of unique significance because it constitutes a single target modulating multiple T cell pathways in EAE/MS. Our findings will help navigate critical miR-92a-related mechanisms in MS that could underlie new therapeutic avenues.