Mechanisms of Disease Pathogenesis in Regulatory T cell Deficiency

Foxp3+调节性T(Tr)细胞是维持外周免疫耐受的关键细胞。这 复杂的种群包括在胸腺和相对较小的胸腺中发育的“自然”TR(NTR)谱系 从外周的传统T细胞产生的不稳定的“诱导”的TR(ITR)细胞。功能丧失Foxp3 人类和小鼠的突变会导致tr细胞缺乏调节活性，导致致命 自身免疫力。在Foxp3充足的宿主中，ITR细胞中Foxp3表达的不稳定性，特别是在 炎症条件下，会产生Foxp3缺陷的EX-ITR细胞，这些细胞是致病的。Foxp3缺陷型tr细胞 继续表达规范tr转录签名的核心要素。然而，他们也获得了一个 表型和转录模式类似于终末分化效应T(Teff)样细胞。他们交换了 他们的能量代谢到有氧糖酵解，表现为mTORC1和mTORC2的激活，并产生Th1，Th2 以及Th17细胞因子，这些细胞因子有助于全身炎症。调节细胞毒性的分子机制 一种teff表型Foxp3缺陷的tr细胞的获得及其抑制功能的消除 仍然默默无闻。为了阐明这些机制，我们创造了一个新的突变的foxp3等位基因(foxP∆EGFPiCre)。 同时取消Foxp3的表达，同时驱动人源化Cre的表达 重组酶(ICre)与增强型绿色荧光蛋白(EGFP)融合。我们证明了 FoxP∆EGFPiCre tr(Δtr)RICTOR的细胞特异性缺失，编码哺乳动物的一个重要组成部分 雷帕霉素复合体靶点2(MTORC2)，实质上改善与Foxp3相关的疾病 缺乏症。Δ细胞中Rictor的缺失恢复了Foxo1的核定位，抑制了Th1的编程， 抑制有氧糖酵解，部分恢复调节活性。因此，我们假设tr细胞 由于遗传或获得性Foxp3缺陷导致的失败是由一组有限但关键的 分子途径，包括mTORC2/AKT/Foxo1轴和有氧糖酵解的代谢调节因子， 它们共同监督Δ、tr和ex-tr细胞向teff样细胞的转化。在这项提案中，我们将 研究这些通路的失调损害Δ受体细胞功能的机制。然后我们将使用 MTORC2/AKT/Foxo1轴抑制和代谢重编程改善ITR的稳定性和功能 基于tr细胞的自身免疫性疾病治疗模型中的细胞。拟议的实验将阐明 Foxp3基因缺失或获得性缺失引起的自身免疫性或调节性疾病的发病机制 表情。关键的是，它们将使旨在挽救监管活动的新疗法的创造成为可能 功能失调的皮质醇细胞。这种治疗方法非常适用于提高糖尿病患者的TR细胞功能。 包括自身免疫和移植物抗宿主病在内的常见疾病状态。

Foxp3+ regulatory T (TR) cells are pivotal to the maintenance of peripheral immunological tolerance. This complex population includes the “natural” TR (nTR) lineage that develops in the thymus and the comparatively unstable “induced” TR (iTR) cells that arise from conventional T cells in the periphery. Loss of function Foxp3 mutations in humans and in mice give rise to TR cells lacking in regulatory activities, resulting in fatal autoimmunity. In Foxp3-sufficient hosts, instability of Foxp3 expression in iTR cells, especially under inflammatory conditions, gives rise to Foxp3-deficient ex-iTR cells that are pathogenic. Foxp3 deficient TR cells continue to express core elements of the canonical TR transcriptional signature. However, they also acquire a phenotype and transcriptional profile similar to terminally differentiated effector T (TEff)-like cells. They switch their energy metabolism to aerobic glycolysis, exhibit mTORC1 and mTORC2 activation and produce Th1, Th2 and Th17 cytokines that contribute to systemic inflammation. The molecular mechanisms mediating the acquisition by Foxp3-deficient TR cells of a TEff phenotype and the abrogation of their suppressive function remain obscure. To elucidate these mechanisms, we have created a novel mutant Foxp3 allele (Foxp∆EGFPiCre) that simultaneously abrogates expression of Foxp3 while driving the expression of a humanized Cre recombinase (iCre) fused with an enhanced green fluorescent protein (EGFP). We demonstrate that Foxp∆EGFPiCre TR (ΔTR) cell-specific deletion of Rictor, which encodes an essential component of the mammalian target of Rapamycin complex 2 (mTORC2), substantially ameliorates the disease associated with Foxp3 deficiency. Rictor deletion in ΔTR cells restores nuclear Foxo1 localization, suppresses Th1 programing, inhibits aerobic glycolysis, and partially rescues regulatory activity. Accordingly, we hypothesize that TR cell failure due to genetic or acquired Foxp3 deficiency is driven by the dysregulation of a limited but critical set of molecular pathways, including the mTORC2/AKT/Foxo1 axis and metabolic regulators of aerobic glycolysis, that together oversee the transformation of the ΔTR and ex-TR cells into TEff -like cells. In this proposal, we will examine the mechanisms by which dysregulation of these pathways impair ΔTR cell function. We will then use mTORC2/AKT/Foxo1 axis inhibition and metabolic reprogramming to improve the stability and function of iTR cells in TR-cell based treatment models of autoimmune disease. The proposed experiments will elucidate the pathogenesis of autoimmune or dysregulatory diseases stemming from genetic or acquired loss of Foxp3 expression. Critically, they will enable the creation of new therapies designed to rescue the regulatory activity of dysfunctional TR cells. Such therapeutic approaches are eminently applicable to boosting TR cell function in common disease states that include autoimmunity and graft versus host disease.