Defining the transcriptional, phenotypic, and functional heterogeneity of virus-specific CD4 T cells during chronic viral infection

通过可溶性因子和细胞表面配体的CD 4“帮助”对于维持CD 8 T细胞应答和体液免疫至关重要。 慢性病毒感染期间的免疫力。最近，我们的实验室进一步确定了CD 4衍生的IL-21的必要性， 在以前未识别的CX 3CR 1 + CD 8 T细胞亚群的形成中表现出有效的细胞溶解功能。 然而，尽管他们的重要作用，我们的理解是如何持续暴露于病毒载量和 炎症塑造辅助性T细胞分化仍然不完全清楚。使用scRNA-seq，我们的实验室 已经产生了大量的初步数据，表明CD 4 T细胞对慢性LCMV感染有反应， 比以前认识到的更异质，有三个转录上不同的子集占主导地位， 抗病毒反应：Cxcr 6 + Th 1、Cxcr 5 +Tfh和Slamf 6+记忆样细胞。值得注意的是，我们的数据进一步表明， CD 4 T细胞对慢性病毒感染而非急性病毒感染有应答，优先将其分化重定向至 这个类似记忆的子集。综上所述，我们假设长期暴露于抗原性和炎症性环境中， 信号（TGF-β、IL-10等）调节病毒特异性CD 4 T细胞的转录多样性， 在慢性病毒感染期间的分化被驱动朝向该记忆样子集以协调以下： 1)减弱Th 1介导的免疫病理学，2）维持可产生Th 1和Tfh的祖细胞库 效应细胞，和3）促进其中记忆样CD 4 T细胞与祖CD 8 T细胞共定位的小生境 将它们的分化重新导向保护性CX 3CR 1 + CD 8 T细胞。在目标1中，我们将进行过继转移 (AT)实验以检查增殖潜力、保护能力和 病毒特异性CD 4 T细胞的三个主要亚群。此外，基于基因调控网络， 由SCENIC（一个R软件包）制定，我们将使用RNA干扰模型来测试关键的贡献。 预测在慢性感染期间在调节CD 4分化中起作用的转录因子。在目标2中， 我们将使用遗传学方法和AT实验来操纵抗原驱动的TCR信号传导， 评估慢性感染期间抗原信号如何调节CD 4分化。此外，我们将阻止 已知在慢性感染期间过表达的免疫调节细胞因子的活性，以确定其 对病毒特异性CD 4 T细胞命运定型的影响。最后，在目标3中，我们将确定IL的AT是否- 21-产生记忆样CD 4 T细胞，无论是单独还是与PD-L1阻断剂联合使用， 祖细胞CX 3CR 1hi CD 8 T细胞转化以改善T细胞介导的免疫。从这件事中获得的知识 这项研究将为CD 4 T细胞在面对疾病时显示的功能适应过程提供机制性见解。 持续感染，并帮助确定旨在优化细胞或体液介导的抗病毒治疗的新策略 免疫力这个职业发展奖提供的额外培训不仅使我能够扩大 我的分子和计算技能，但也将独特的定位我建立一个独立的研究 该计划侧重于解决与CD 4 T细胞免疫生物学有关的基本问题。

CD4 “help” via soluble factors and cell-surface ligands is critical to sustain CD8 T cell responses and humoral immunity during chronic viral infection. Recently, our lab has further identified a necessity for CD4-derived IL-21 in the formation of a previously unrecognized CX3CR1+CD8 T cell subset that exhibits potent cytolytic function. However, despite their essential role, our understanding of how persistent exposure to viral load and inflammation shapes helper T cell differentiation remains incompletely understood. Using scRNA-seq, our lab has generated substantial preliminary data demonstrating that CD4 T cells responding to chronic LCMV infection are more heterogenous than previously appreciated, with three transcriptionally distinct subsets dominating the antiviral response: Cxcr6+Th1, Cxcr5+Tfh, and Slamf6+ memory-like cells. Notably, our data further indicate that CD4 T cells responding to chronic, but not acute viral infection, preferentially redirect their differentiation towards this memory-like subset. Taken together, we hypothesize that prolonged exposure to antigenic and inflammatory signals (TGF-β, IL-10 etc.) modulate the transcriptional diversity of virus-specific CD4 T cells, and that CD4 differentiation during chronic viral infection is driven towards this memory-like subset to coordinate the following: 1) attenuate Th1-mediated immunopathology, 2) maintain a progenitor pool that can give rise to Th1 and Tfh effector cells, and 3) facilitate a niche wherein memory-like CD4 T cells co-localize with progenitor CD8 T cells to redirect their differentiation towards protective CX3CR1+CD8 T cells. In Aim 1, we will perform adoptive transfer (AT) experiments to examine the proliferative potential, protective capacity, and lineage relationship between the three major subsets of virus-specific CD4 T cells. Additionally, based on the gene regulatory network formulated by SCENIC (an R package), we will use RNA interference models to test the contribution of key transcription factors predicted to play a role in regulating CD4 differentiation during chronic infection. In Aim 2, we will use genetic approaches and AT experiments to manipulate antigen-driven TCR-signaling in order to assess how antigenic signals regulate CD4 differentiation during chronic infection. Moreover, we will block the activity of immunoregulatory cytokines known to be overexpressed during chronic infection to determine their impact on the fate commitment of virus-specific CD4 T cells. Lastly, in Aim 3 we will determine whether AT of IL- 21-producing memory-like CD4 T cells, either alone or in conjunction with PD-L1 blockade, can augment progenitorCX3CR1hi CD8 T cell transition to improve T cell-mediated immunity. Knowledge gained from this research will provide mechanistic insights into the functional adaption process CD4 T cells display in the face of persistent infection and help identify novel strategies aimed at optimizing cellular or humoral-mediated antiviral immunity. The additional training afforded by this career development award will not only enable me to expand my molecular and computational skillsets, but will also uniquely position me to build an independent research program focused on addressing fundamental questions pertaining to CD4 T cell immunobiology.