Metabolic Control of Systemic Autoimmunity

摘要 系统性红斑狼疮（SLE）是一种病因不明的自身免疫性疾病。发病机制 部分归因于免疫系统内外的分隔化氧化应激。拟议 研究将集中在一个关键的知识缺口-如何代谢途径，中和氧化应激控制 SLE的自身免疫该项目的中心假设是基于全面的代谢组学研究 显示SLE对淋巴细胞中戊糖磷酸途径（PPP）的主要影响， 患者和狼疮倾向小鼠的T细胞经历谱系极化;其结果模拟了 转醛醇酶（TAL）缺乏，转醛醇酶是PPP的限速酶。易患狼疮的小鼠表现出 雷帕霉素（mTOR）和肝线粒体氧化应激的机制靶点和抗磷脂 抗体（aPL）的生产之前的肾炎发作。与狼疮易感品系相似，缺乏TAL的小鼠表现出 线粒体电子传递中复合物I亚基NDUFS 3的mTOR激活和过表达 链（ETC），触发活性氧中间体（ROI）和aPL的产生，两者都响应 雷帕霉素治疗。TAL缺乏阻断了肝脏对PON 1的糖基化和分泌。这是 归因于PPP中的碳捕获和UDP-GlcNAc的消耗，这在SLE患者中也可检测到 和老鼠。虽然血浆中PON 1的丢失与aPL的产生有关，并在SLE中得到证实， 抗磷脂综合征（APS）和肝脏疾病，其潜在机制仍不清楚。因此，我们认为， 具体目标将检验我们的工作假设，即TAL失活i）消除细胞类型特异性碳 螯合PPP和限制底物NADPH和GSH的生产和代谢，通过 ETC，从而触发氧化应激产生的线粒体，mTOR的代偿性积累 途径激活和免疫系统中的促炎谱系偏斜;和ii）限制了 UDP-GlcNAc用于糖基化和肝脏分泌PON 1，进而触发SLE中aPL的产生 缺乏TAL。在目标1下，我们将检验TAL通过PPP调节碳通量的假设， 引起景天庚酮糖7-磷酸的细胞类型特异性积累，NADPH和GSH的消耗，和 氧化还原介导的mTOR活化促进Th 17、Tfh和DN T细胞的扩增以及CD 8 SLE患者中EMT细胞和T细胞亚群在目标2下，我们将描述T细胞内在代谢检查点， 控制狼疮易感小鼠的全身性自身免疫。根据目标3，我们将确定肝细胞的作用- aPL产生中的衍生氧化应激、免疫系统中的促炎谱系偏斜和狼疮 发病机制这项拟议中的研究意义重大，因为它将建立一个新的， 自身免疫的代谢检查点与发病机制和治疗具有广泛的翻译相关性 关于SLE该方法是创新的，因为它将采用氧化应激和高分辨率的遗传检查点。 稳定同位素示踪代谢途径以描述狼疮发病机制。

ABSTRACT Systemic lupus erythematosus (SLE) is an autoimmune disease of unknown etiology. The pathogenesis is partly attributed to compartmentalized oxidative stress inside and outside the immune system. The proposed studies will focus on a critical gap in knowledge - how metabolic pathways that neutralize oxidative stress control autoimmunity in SLE. The central hypothesis for this project is based on comprehensive metabolome studies that have showed a dominant impact of SLE on the pentose phosphate pathway (PPP) in lymphocytes of patients and T cells of lupus-prone mice undergoing lineage polarization; the results of which mimic the deficiency of transaldolase (TAL), a rate-limiting enzyme of the PPP. Lupus-prone mice exhibit activation of the mechanistic target of rapamycin (mTOR) and mitochondrial oxidative stress in the liver and antiphospholipid antibody (aPL) production prior to the onset of nephritis. Similar to lupus-prone strains, mice lacking TAL exhibit mTOR activation and overexpression of NDUFS3, a subunit of complex I in the mitochondrial electron transport chain (ETC) that triggers the production of reactive oxygen intermediates (ROI) and aPL, both of which respond to rapamycin treatment. TAL deficiency blocks the glycosylation and secretion of PON1 by the liver. This is attributed to carbon trapping in the PPP and depletion of UDP-GlcNAc which are also detectable in SLE patients and mice. Although PON1 loss in the plasma has been connected to aPL production and demonstrated in SLE, antiphospholipid syndrome (APS), and liver diseases, the underlying mechanisms remain unknown. Therefore, the Specific Aims will test our working hypothesis that TAL inactivation i) elicits cell type-specific carbon sequestration in the PPP and limits substrates for NADPH and GSH production and metabolism through the ETC and thus triggers a compensatory accumulation of oxidative stress-generating mitochondria, mTOR pathway activation and pro-inflammatory lineage skewing in the immune system; and ii) limits the availability of UDP-GlcNAc for glycosylation and secretion of PON1 by the liver, which in turn trigger aPL production in SLE and TAL deficiency. Under Aim 1, we will test the hypothesis that TAL-regulated carbon flux through the PPP causes cell-type specific accumulation of sedoheptulose 7-phosphate, depletion of NADPH and GSH, and redox-mediated mTOR activation to promote the expansion Th17, Tfh, and DN T cells and constriction of CD8 EMT cells and Tregs in SLE patients. Under Aim 2, we will delineate T-cell intrinsic metabolic checkpoints that control systemic autoimmunity in lupus-prone mice. Under Aim 3, we will determine the role of hepatocyte- derived oxidative stress in aPL production, pro-inflammatory lineage skewing in the immune system and lupus pathogenesis. The proposed research is significant because it will establish new, compartmentally defined metabolic checkpoints of autoimmunity with broad translational relevance for the pathogenesis and treatment of SLE. The approach is innovative as it will employ genetic checkpoints of oxidative stress and high-resolution stable isotope tracing of metabolic pathways to delineate lupus pathogenesis.