Epigenetic imprinting of follicular helper T cell fate and function in lupus

摘要 狼疮中存在的抗核自身抗体（ANA）是高亲和力的、类别转换的Ab，其通过以下途径产生： T细胞依赖性生发中心（GC）反应。GC的开发和持久化依赖于 滤泡辅助CD 4 + T细胞（TFH）。虽然TFH的异常发育和功能在两种疾病中都有驱动作用， SLE患者和狼疮的小鼠模型，启动和加强免疫调节的分子和细胞途径， TFH的命运仍然不明确。这限制了我们剖析狼疮背后改变的生物学的能力。 此外，由于缺乏获得次级淋巴组织的途径，人TFH的研究受到阻碍 它们在那里分化并发挥作用。表观遗传密码的变化介导了同一性、特异性、稳定性， 和分化的CD 4 + T辅助（Th）细胞亚群的功能。事实上，表观遗传景观可能是一个 Th亚群之间发育和功能关系的更好指标，而不是谱系特异性 转录因子在初步数据中，我们的表观遗传分析显示， 易感性GWAS SNP定位于TFH开放染色质区域，表明TFH生物学改变 介导狼疮遗传风险的重要组成部分。 我们以前使用独特的小鼠模型来定义TFH分化的离散阶段： 使CD 4 + T细胞向表达Bcl 6和CXCR 5的不稳定的前TFH中间体致敏。同源T-B 相互作用驱动前TFH产生IL-21，表达PD-1，并抑制IL-17的产生。初步 表观遗传学分析证实，前TFH并不完全致力于TFH的命运，并表明我们可以确定一个 B细胞依赖性模块。然而，B细胞MHCII表达--不需要DC引发--就足够了 在类似于狼疮的免疫学环境中进行TFH分化。 该提案将利用独特的小鼠模型和原代人类细胞来建立表观遗传路线图 对过渡联邦政府命运的承诺将利用具有有限MHCII表达的狼疮倾向小鼠来 定义CD 4 + T细胞和DC之间的顺序相互作用，然后是B细胞介导的变化， 表观遗传密码前-TFH和TFH的ATAC-Seq分析将鉴定调节级联、转录和转录调控。 因子程序以及在TFH分化期间由DC和B细胞调节的代谢途径。 其次，我们将建立在这些分析，以确定如何狼疮破坏这种转录和功能 程序.做狼疮：1.改变了对连续cDC和B细胞抗原呈递的要求， TFH的分化和维持？或2.破坏TFH分化的表观遗传景观， 承诺？这些实验应该确定表观遗传签名，1。定义B细胞贡献 向TFH分化; 2.区分狼疮和健康对照中的TFH。这些结果将提供 未来的治疗干预框架，以改善疾病。

ABSTRACT The anti-nuclear autoantibodies (ANA) present in lupus are high-affinity, class-switched Abs that arise through T cell-dependent germinal center (GC) reactions. GC development and persistence is dependent on help from Follicular Helper CD4+ T cells (TFH). Although aberrant development and function of TFH drive disease in both SLE patients and murine models of lupus, the molecular and cellular pathways that initiate and reinforce the TFH fate remain poorly defined. This limits our ability to dissect the altered biology underlying lupus. Additionally, the study of human TFH has been hampered by lack of access to the secondary lymphoid tissues where they differentiate and function. Changes in the epigenetic code mediate the identity, specificity, stability, and function of differentiated CD4+ T helper (Th) cell subsets. Indeed, the epigenetic landscape may be a better indicator of the developmental and functional relationships amongst Th subsets than lineage-specific transcription factors. In preliminary data, our epigenetic analyses show that a significant number of lupus susceptibility GWAS SNPs map to regions of open chromatin in TFH, suggesting that altered TFH biology mediates a significant component of lupus genetic risk. We previously used unique murine models to define discreet stages of TFH differentiation: conventional DCs prime CD4+ T cells toward an unstable pre-TFH intermediate that expresses Bcl6 and CXCR5. Cognate T-B interactions drive the pre-TFH to produce IL-21, express PD-1, and repress production of IL-17. Preliminary epigenetic analyses confirm that pre-TFH are not fully committed to the TFH fate and show that we can identify a B cell-dependent module. However, B cell MHCII expression--with no requirement for DC priming--is sufficient for TFH differentiation in immunological settings similar to lupus. The proposal will utilize unique murine models and primary human cells to establish the epigenetic roadmap that defines commitment to the TFH fate. Lupus-prone mice with limited expression of MHCII will be utilized to define how sequential interactions between CD4+ T cells and DCs followed by B cells mediate changes in the epigenetic code. ATAC-Seq analyses of pre-TFH and TFH will identify the regulatory cascades, transcription factor programs, and metabolic pathways that are regulated by DCs and B cells during TFH differentiation. Secondly, we will build on these analyses to define how lupus disrupts this transcriptional and functional program. Does lupus: 1. alter the requirement for sequential cDC and B cell antigen presentation in the differentiation and maintenance of TFH? or 2. disrupt the epigenetic landscape of TFH differentiation and commitment? These experiments should identify the epigenetic signatures that 1. Define the B cell contribution to TFH differentiation and 2. Distinguish TFH in lupus and health controls. These results will provide the framework for future therapeutic interventions to ameliorate disease.