Epigenetic programming of T follicular helper cell differentiation

项目摘要 滤泡辅助性T细胞（Tfh）是一种专门的T细胞亚群，直接帮助B细胞形成 老年中心在生殖中心内，B细胞经历抗体亲和力成熟，类别转换， 以及长寿浆细胞和记忆B细胞的分化。辅助性T细胞反应对于 长寿命抗体介导的免疫保护，其通过不存在长寿命抗体来证明 在Tfh缺陷的个体和动物中，免疫应答和免疫缺陷的呈现。以下 通过病毒感染或免疫激活初始CD4 T细胞，这些新激活的T细胞解释了各种 诱导转录因子的信号，这些转录因子指导特定的基因表达变化。协同 这些基因表达变化发生在T辅助细胞分化过程中，基因发生DNA甲基化， 控制表达或相关基因的调控元件中CpG基序的变化。DNA甲基化作用 作为一种抑制性表观遗传标记，去甲基化过程与表达能力有关， 对细胞功能重要的基因。甲基化的变化是由泰特双加氧酶催化的， 去甲基化过程和DNA甲基转移酶，促进新的（从头）甲基化， 不相关的基因。本建议中具体目标的广泛目标是了解如何 T滤泡辅助细胞通过去甲基化或从头开始进行DNA甲基化编程 甲基化，以及操纵这种编程是否可以增强或损害T滤泡辅助细胞 功能，从而影响对疫苗接种或感染的抗体应答。本提案的具体目标 目的1）探讨Tet2在调节Th1细胞和Th2细胞平衡及记忆中的作用 目的2）明确从头甲基化在调节Tfh和Th1记忆细胞中的作用 目的3）确定DNA甲基转移酶抑制是否可以 促进Tfh分化并增强抗Tfh免疫后抗体介导的免疫保护 流感挑战这些研究将利用细胞免疫学方法，基因表达和整体 基因组DNA甲基化分析，免疫和传染病挑战，以评估 DNA甲基化编程在T滤泡辅助细胞分化、功能和记忆中重要性 阵总之，这些目标将联合收割机提供一个机制评估如何T滤泡辅助细胞， 细胞分化，识别和表征新的途径，可以有针对性地产生更有效的 可以提高持久免疫力的疫苗接种策略。

Project Summary T follicular helper cells (Tfh) are a specialized subset of T cells that directly provide help to B cells to form germinal centers. Within germinal centers, B cells undergo affinity maturation of antibodies, class switching, and differentiation of long-lived plasma cells and memory B cells. T follicular helper responses are vital to long-lived antibody-mediated immune protection, which is demonstrated by the absence of long-lived antibody responses and the presentation of immune deficiency in Tfh-deficient individuals and animals. Following activation of naïve CD4 T cells by viral infection or immunization, these newly activated T cells interpret various signals that induce transcription factors that direct specific gene expression changes. In coordination with these gene expression changes that occur during T helper cell differentiation, genes undergo DNA methylation changes at CpG motifs in regulatory elements that control expression or relevant genes. DNA methylation acts as a repressive epigenetic mark, and the process of demethylation is associated with the ability to express genes important for cell function. Changes in methylation are catalyzed by Tet dioxygenases that participate in the processes of demethylation, and DNA methyltransferases that promote new (de novo) methylation to turn off irrelevant genes. The broad objectives of the specific aims in this proposal are to gain understanding of how T follicular helper cells undergo DNA methylation programing, either through demethylation or de novo methylation, and whether manipulation of such programing can enhance or impair T follicular helper cell function and thus influence antibody responses to vaccination or infection. The specific aims for this proposal are: Aim 1) Determine the role of Tet2 in regulating the balance of T follicular helper and Th1 cell and memory cell differentiation; Aim 2) Define the role of de novo methylation in regulating Tfh and Th1 memory cell differentiation and lineage commitment; and Aim 3) Determine whether DNA methyltransferase inhibition can promote Tfh differentiation and enhance antibody-mediated immune protection following immunization against influenza challenge. These studies will utilize cellular immunology approaches, gene expression and whole genome DNA methylation analyses, and immunization and infectious disease challenge to evaluate the importance of DNA methylation programing in T follicular helper cell differentiation, function, and memory formation. Together, these aims will combine to provide a mechanistic evaluation of how T follicular helper cells differentiate and identify and characterize novel pathways that can be targeted to generate more effective vaccination strategies that can improve long-lasting immunity.