Elucidating the distinct roles of T cell-polarized microglia in glioblastoma suppression and progression

项目总结/摘要 胶质母细胞瘤是一种IV级弥漫性星形细胞瘤，是成人脑癌中最致命和最常见的形式。 标准护理可延长生存期约1 - 18个月，老年人受益最少 患者（> 70岁）。新形式的免疫疗法，包括免疫检查点抑制剂（ICI）， 治疗原发性和复发性胶质母细胞瘤的关键。不幸的是，迄今为止还没有临床试验表明 对这些患者的生存或免疫参与有重大益处。最近的研究结果表明， 隐藏着多重和交织的免疫抑制细胞源，抑制ICI引发的反应。 因此，一种解决方案可能是不仅通过阻断诸如CTLA-4和PD-1的检查点来增强效应T细胞， 1，但也针对胶质母细胞瘤中的免疫抑制小生境，其中最大的是由神经胶质瘤- 相关的小胶质细胞和巨噬细胞（GAM）。事实上，GAM是一个非常有吸引力的目标， 在临床前和临床研究中通过CSF1R抑制消除（PLX3397）。然而，这种方法产生了 模型中的反应混合，患者中无反应。另一条途径可能是重新编程GAM，但我们缺乏 深入了解促进抗肿瘤GAM的途径。因此，识别细胞和分子 促肿瘤和抗肿瘤GAM状态的调节剂是解锁新治疗途径的下一步。最近的工作 Kaech实验室的研究表明，在胶质母细胞瘤的原位小鼠模型中，CTLA-4阻断降低了对神经元的调节作用。 T细胞（Treg）浸润，"辅助" Th1细胞浸润增加，小胶质细胞暴露于Th1细胞衍生的IFNg 被重编程为抗原呈递（MHCII+）、肿瘤吞噬（AXL +/MER+）状态;一致地， 这些效果显著提高了存活率。这项提案将研究GAM，特别是大脑， 常驻小胶质细胞，获得和维持不同的功能状态的假设，Treg特异性信号转导 在胶质母细胞瘤进展期间维持促肿瘤的GAM，而Th1 T细胞诱导肿瘤杀伤的GAM 在ICI发起的有效反应期间。提出了两个具体的目标来质疑这一假设。第一 aim将采用单细胞空间转录组学来研究Tcl4和Th1细胞是否是外源性调节因子 GAM状态通过直接接触和/或分泌信号，以及这些相互作用轴是否存在于 人类胶质母细胞瘤第二个目标将确定内在的AXL/MER和相关的途径调节GAM 状态“切换”。总之，这项工作将通过界定如何渗透， T细胞和GAM内在信号通路协调促肿瘤和抗肿瘤的动态生物学 GAM州。此申请概述了申请人的拟议培训计划，其中包括多样化和 多学科研究指导，尖端和先进技术的培训，以及 更广泛的科学技能，如合作和有效的沟通。中概述的研究和培训 该提案将为申请人进行创新，严谨和有影响力的研究做好准备。

Project Summary/Abstract Glioblastoma is a grade IV diffuse astrocytoma, the deadliest and most common form of adult brain cancer. Standard of care extends survival by approximately 1-18 months, with the poorest benefits being seen by elderly patients (>70yrs). New forms of immune-based therapies, including immune checkpoint inhibitors (ICI), may turn the corner in treatments for primary and recurrent glioblastoma. Unfortunately, no clinical trial so far has shown major benefits in either survival or immune engagement for these patients. Recent findings suggest that gliomas harbor multiple and intertwined cellular sources of immune suppression that dampen ICI-initiated responses. Thus, one solution may be to not only enhance effector T cells by blocking checkpoints such as CTLA-4 and PD- 1, but to also target the immune suppressive niches in glioblastoma, the largest of which is comprised of glioma- associated microglia and macrophages (GAMs). In fact, GAMs are a highly attractive target and have been depleted in pre-clinical and clinical studies via CSF1R inhibition (PLX3397). This approach, however, yielded mixed responses in models and no response in patients. Another path may be to reprogram GAMs, but we lack insights into the pathways that promote anti-tumor GAMs. Therefore, identifying the cellular and molecular regulators of pro- and anti-tumor GAM states is the next step in unlocking new therapeutic avenues. Recent work by the Kaech lab showed that CTLA-4 blockade in orthotopic mouse models of glioblastoma reduced regulatory T cell (Treg) infiltration, increased ‘helper’ Th1 cell infiltration, and microglia exposed to Th1 cell-derived IFNg were reprogrammed into an antigen presenting (MHCII+), tumor-phagocytosing (AXL+/MER+) state; in concert, these effects significantly increased survival. This proposal will investigate how GAMs, especially the brain resident microglia, acquire and maintain distinct functional states with the hypothesis that Treg-specific signaling sustains tumor-promoting GAMs during glioblastoma progression while Th1 T cells induce tumor-killing GAMs during an effective ICI-initiated response. Two specific aims are proposed to interrogate this hypothesis. The first aim will employ single-cell spatial transcriptomics to address whether Tregs and Th1 cells are extrinsic regulators of GAM states through direct contact and/or secretory signaling, and whether these interaction axes exist in human glioblastoma. The second aim will define the intrinsic AXL/MER and related pathways regulating GAM state ‘switching’. In summary, this work will better inform GAM-targeting interventions by defining how infiltrating T cells and GAM-intrinsic signaling pathways coordinate the dynamic biology underlying pro- and anti-tumor GAM states. This application outlines the applicant’s proposed training plan, which includes diverse and multidisciplinary research mentorship, training in cutting-edge and advanced techniques, and development of broader scientific skills such as collaboration and effective communication. The research and training outlined in this proposal will prepare the applicant to conduct innovative, rigorous, and impactful research.