Metabolic Control of T-cell Lineage Specification in SLE

 描述(由申请人提供)：系统性红斑狼疮(SLE)的病因尚不清楚，然而，其发病机制至少部分归因于T细胞功能障碍。初步研究显示，狼疮T细胞中雷帕霉素复合体1(MTORC1)的机械靶点被激活，这是疾病爆发的先兆，并导致SLE患者的促炎谱系特征。MTORC1上游，还原型谷胱甘肽(GSH)的耗尽，活性氧中间产物(ROI)的增加，以及有丝分裂的缺陷是新发现的。一项双盲安慰剂对照临床试验的结果表明，N-乙酰半胱氨酸(NAC)逆转GSH耗竭的治疗作用可在体内阻断mTORC1。因此，拟议的研究将通过确定控制氧化应激和正常T细胞发育的代谢途径如何有助于狼疮的发病，来解决一个关键的知识差距。中心假说是，GSH耗竭主要通过依赖mTORC1的促炎T细胞的扩张来推动SLE的发病。这项拟议研究的基本原理是，在阐明了基因控制的代谢之后 促进GSH耗竭和mTORC1激活从而触发狼疮发病的途径，新的和潜在的协同作用方法可以用于SLE的预防和治疗。在令人信服的初步数据的指导下，我们的假设将在三个特定目标下进行检验：1)描绘导致狼疮T细胞中氧化应激产生线粒体积累的代谢程序；2)在SLE患者的纵向研究中确定GSH耗竭在mTORC1依赖的T细胞谱系指定中的作用；以及3)确定GSH耗竭在狼疮易感小鼠系统性自身免疫发病机制中的作用。在目标1下，将评估电子传递链复合体I中ND3亚基的S亚基亚基以及ND2和ATP6中的狼疮连锁线粒体DNA(MtDNA)多态是ROI产生增加的原因。在Aim 2中，GSH耗竭和mTORC1激活将在体外以基因靶点逆转促炎T细胞的发育，重点是CREM-a/IL-4介导的CD8 T细胞向DNT细胞的反转分化和HIF1a/IL-17介导的SLE患者Tregs的耗竭。在目标3中，谷胱甘肽耗竭将通过转醛醇酶失活来模拟，并被评估为狼疮易感小鼠的疾病发病机制的一个原因。这项拟议的研究具有重要意义，因为它将促进我们对正常和自身免疫条件下T细胞谱系发展的理解，并与确定SLE新的治疗靶点相关。这种方法是创新的，因为它通过利用代谢途径基因来调节T细胞的发育，从而改变了现状。这一结果将为我们理解控制氧化应激的代谢途径及其在疾病发病机制中的作用开辟新的视野，同时为SLE的治疗提供新的机制靶点。

 DESCRIPTION (provided by applicant): The causes of systemic lupus erythematosus (SLE) are unknown, however, the pathogenesis is attributed, at least in part, to T-cell dysfunction. Preliminary studies reveal activation of the mechanistic target of rapamycin complex 1 (mTORC1) in lupus T cells which precedes disease flares and causes pro-inflammatory lineage specification in SLE patients. Upstream of mTORC1, depletion of reduced glutathione (GSH), enhanced production of reactive oxygen intermediates (ROI), and defective mitophagy are newly identified. Outcomes of a double-blind placebo-controlled clinical trial show that therapeutic reversal of GSH depletion by N-acetylcysteine (NAC) blocks mTORC1 in vivo. Therefore, the proposed studies will address a critical knowledge gap by determining how metabolic pathways that control oxidative stress and normal T-cell development contribute to lupus pathogenesis. The central hypothesis is that primarily GSH depletion drives the pathogenesis of SLE through mTORC1-dependent expansion of pro-inflammatory T cells. The rationale for the proposed research is that, after elucidating the genetically controlled metabolic pathways that promote GSH depletion and mTORC1 activation and thus trigger lupus pathogenesis, new and potentially synergistic approaches can be used for prevention and treatment of SLE. Guided by compelling preliminary data, our hypothesis will be tested in three Specific Aims: 1) to delineate the metabolic program that causes the accumulation of oxidative stress-generating mitochondria in lupus T cells; 2) to identify the role of GSH depletion in mTORC1-dependent T-cell lineage specification in longitudinal studies of SLE patients; and 3) to determine the role of GSH depletion in the pathogenesis of systemic autoimmunity in lupus-prone mice. Under Aim 1, S-nitrosylation of ND3 subunit in complex I of the electron transport chain and lupus-linked mitochondrial DNA (mtDNA) polymorphisms in ND2 and ATP6 will be assessed as causes of increased ROI production. Under Aim 2, GSH depletion and mTORC1 activation will be genetically targeted in vitro for reversing pro-inflammatory T-cell development focusing on CREM-a/IL-4-mediated trans-differentiation of CD8 T cells to DN T cells and HIF1a/IL-17-mediated depletion of Tregs in SLE patients. Under Aim 3, GSH depletion will be modeled by the inactivation of transaldolase and evaluated as a cause of disease pathogenesis in lupus-prone mice. The proposed research is significant because it will advance our understanding of T-cell lineage development in normal and autoimmune conditions with relevance for identifying new treatment targets in SLE. The approach is innovative as it departs from the status quo by utilizing metabolic pathway genes to regulate T-cell development. The results will open new horizons in our understanding of the metabolic pathways that control oxidative stress and its role in disease pathogenesis while providing new mechanistic targets for treatment of SLE.