Investigating molecular mechanism of T cell exhaustion in chronic infection and tumor microenvironment

项目摘要 T细胞耗竭是指慢性抗原暴露后T细胞功能失调的状态，这种耗尽的T细胞 (Tex)常在慢性感染或肿瘤微环境中发生。Tex的主要功能之一是 抑制分子如细胞毒性T淋巴细胞抗原4(CTLA-4)和 程序性死亡1(PD-1)。这些分子作为免疫检查点抑制T细胞功能 以防止T细胞过度激活造成的病理损害。然而，在肿瘤微环境中， 这些分子限制了T细胞杀伤肿瘤的细胞毒作用。阻止这些免疫检查点 已被证明在多种癌症类型中取得了显著的临床益处。尽管取得了这些成功，但 大多数患者不能实现长期的肿瘤缓解。因此，研究潜在的 T细胞衰竭发生的分子机制，并寻找潜在的联合策略 免疫检查点阻断(ICB)在临床上用于增强和维持T细胞应答。 在我的博士研究期间，我专注于研究T细胞耗竭的转录机制 发展，以及转录因子如何在PD-1阻断后控制T细胞的恢复。以特定的目标 1.1，我重点研究了效应器T细胞丢失和Tex祖细胞建立的转录机制 在慢性抗原暴露期间。使用单细胞RNA测序(sc-RNA-Seq)，我们发现了两个明显不同的 在慢性效应T细胞和TeX祖细胞中的转录网络，我们系统地 阐述了Tex发育的分子机制。在具体目标1.2中，我专注于建立T细胞 基于体内CRISPR-Cas9筛选系统(RetroCRISPR)的转录功能研究 PD-1阻断T细胞活化的机制。这些研究不仅将发现新的 T细胞耗尽的机制，但也提供高维图谱或高通量筛选 用于实地研究T细胞反应的系统。在具体目标2中，我计划扩展我的RetroCRISPR系统 解剖肿瘤微环境的复杂性，并寻找潜在的组合 通过ICB增强T细胞反应的策略。我当前项目和未来计划的总体目标是 发现影响T细胞应答的细胞内、外机制，设计最佳免疫方案 肿瘤长期缓解的治疗策略。

Project Summary T cell exhaustion is a dysfunctional T cell state after chronic antigen exposure, and this exhausted T cells (TEX) are often developed in chronic infection or tumor microenvironment. One of the key features of TEX is increased expression of inhibitory molecules such as Cytotoxic T Lymphocyte Antigen 4 (CTLA-4) and Programmed Death 1 (PD-1). These molecules work as immune checkpoints to suppress T cell function in order to prevent pathological damage from T cell hyper-activation. However, in the tumor microenvironment, these molecules limit the cytotoxic effect of T cells to kill tumor. Blocking these immune checkpoints has been shown to achieve significant clinical benefits in multiple cancer types. Despite of these successes, the majority of the patients do not achieve long-term tumor remission. Thus, it is crucial to study the underlying molecular mechanism of T cell exhaustion development, and seek for potential combination strategies with immune checkpoint blockade (ICB) to enhance and sustain T cell response in clinic. During my doctoral research, I focus on investigating the transcriptional mechanisms of T cell exhaustion development, and how transcription factors control T cell reinvigoration after PD-1 blockade. In Specific Aim 1.1, I focused on the transcriptional mechanisms of effector T cell loss and TEX progenitor establishment during chronic antigen exposure. Using single cell RNA sequencing (sc-RNA-Seq), we found two distinct transcriptional networks in the chronic effector T cells and the TEX progenitors, and we systematically described the molecular mechanism of TEX development. In Specific Aim 1.2, I focus on establishing a T cell based in vivo CRISPR-Cas9 screening system (RetroCRISPR) to functionally study transcriptional mechanisms during T cell reinvigoration by PD-1 blockade. These studies will not only discover novel mechanisms of T cell exhaustion, but also provide high dimensional profiling or high throughput screening systems for the field to study T cell response. In Specific Aim 2, I plan to extend my RetroCRISPR system into dissecting the complexity of tumor microenvironment, and I will search for potential combination strategies with ICB to enhance T cell response. The overall goal for my current projects and future plans is to discover cell intrinsic and extrinsic mechanisms affecting T cell response, and design optimal immune therapeutic strategies for long-term tumor remission.