A TCF1:Glucocorticoid regulatory circuit controls IL-23-driven Th17 pathogenicity

项目摘要 产生CD4 + IL-17的T辅助细胞（Th17）是中枢神经系统（CNS）自身免疫性疾病的已知驱动因子。 多发性硬化症（MS）的炎症，但并非所有的Th17细胞驱动疾病。事实上，两种主要的Th17亚型 已经在小鼠和人类中进行了描述：稳态或非致病性（npTh17），其维持 组织中稳态和驱动破坏性组织炎症的炎性或致病性Th17（pTh17）。 重要的是，npTh17是pTh17的前体，已知IL-23是npTh17转化的开关因子 pTh17然而，IL-23驱动这种转化的机制还不清楚。识别 这些机制将为MS的新治疗干预的开发提供关键的见解。 编码转录因子TCF-1的基因TCF 7的遗传变异与疾病有关 在全基因组关联研究中，MS的易感性，但潜在的机制仍然未知。 值得注意的是，TCF-1与Th17生物学有关，但由于相互矛盾的数据，其作用仍不清楚 在T细胞发育缺陷或间接研究TCF-1的模型中产生。使用的老鼠 仅在成熟T细胞中有条件地缺失Tcf7，从而具有正常的T细胞发育，我们发现， TCF-1缺陷型Th17细胞可能不需要IL-23 R信号来获得致病潜力。我确已 发现TCF-1在体内npTh17和pTh17中受到不同的调节，并且IL-23关闭TCF-1 表情我们的初步数据进一步揭示了一个假定的调节回路，该回路将IL-23、TCF-1和 内源性糖皮质激素（GC）信号传导。我们已经发现npTh17是类固醇生成的。就能够创造出 GC，其反过来维持TCF-1表达，对抗IL 23 R信号传导，并抑制Th17致病性。在 相反，IL-23关闭了npTh17细胞中的类固醇生成。因此，我们假设TCF-1- 糖皮质激素调节回路决定IL-23驱动的Th17细胞致病性。我们已经生成 几种新的条件性基因敲除小鼠，我们可以用它们研究糖皮质激素受体TCF-1的作用。 (GR)和成熟T细胞中特异性的细胞内类固醇生成。我们将使用这些工具， 剖析这种新的调节回路。我们提出以下目的：1）明确TCF-1在对抗IL-2中的作用， 23-驱动的Th17致病性; 2）确定糖皮质激素信号传导如何调节TCF-1表达、IL 23 R 信号传导和Th17致病性;和3）确定细胞内源性类固醇生成在对抗Th17中的作用 致病性 考虑到TCF7的遗传变异与TCF7基因突变的相关性，我们提出的研究具有高度的临床意义。 MS的易感性和使用GC治疗复发缓解型MS（RR-MS）患者的复发。

PROJECT SUMMARY CD4+ IL-17-producing T helper cells (Th17) are known drivers of central nervous system (CNS) autoimmune inflammation in multiple sclerosis (MS), yet not all Th17 cells drive disease. Indeed, two major Th17 subtypes have been described in both mice and humans: homeostatic or non-pathogenic (npTh17) that maintain the steady state in tissue and inflammatory or pathogenic Th17 (pTh17) that drive destructive tissue inflammation. Importantly, npTh17 are precursors of pTh17 and IL-23 is known to be the switch factor for conversion of npTh17 to pTh17. However, the mechanisms by which IL-23 drives this conversion are not well understood. Identifying these mechanisms will provide critical insight for the development of novel therapeutic interventions for MS. Genetic variants in TCF7, the gene encoding the transcription factor TCF-1, have been associated with disease susceptibility in MS in genome-wide association studies, but the underlying mechanisms remain unknown. Notably, TCF-1 has been implicated in Th17 biology, but its role remains unclear due to conflicting data generated in models that have either defective T cell development or that study TCF-1 indirectly. Using mice that conditionally delete Tcf7 only in mature T cells, and thus have normal T cell development, we have found that TCF-1-deficient Th17 cells may not require IL-23R signaling for acquiring pathogenic potential. Indeed, we have found that TCF-1 is differentially regulated in npTh17 and pTh17 in vivo and that IL-23 shuts down TCF-1 expression. Our preliminary data further uncover a putative regulatory circuit that links IL-23, TCF-1, and endogenous glucocorticoid (GC) signaling. We have found that npTh17 are steroidogenic. They can produce GCs, which in turn, sustain TCF-1 expression, oppose IL23R signaling, and restrain Th17 pathogenicity. In contrast, IL-23 shuts down steroidogenesis in npTh17 cells. Accordingly, we hypothesize that a TCF-1- glucocorticoid regulatory circuit determines IL-23-driven pathogenicity in Th17 cells. We have generated several novel conditional knock-out mice with which we can study the role of TCF-1, the glucocorticoid receptor (GR), and cell-intrinsic steroidogenesis specifically in mature T cells. We will use these tools to mechanistically dissect this novel regulatory circuit. We propose the following aims: 1) Define the role of TCF-1 in opposing IL- 23-driven Th17 pathogenicity; 2) Determine how glucocorticoid signaling regulates TCF-1 expression, IL23R signaling, and Th17 pathogenicity; and 3) Determine the role of cell-intrinsic steroidogenesis in opposing Th17 pathogenicity. Our proposed investigation is highly clinically relevant given the association of genetic variants of TCF7 with susceptibility to MS and the use of GCs to treat relapses in patients with relapsing-remitting MS (RR-MS).