Modulation of Microglia and T Cell Interactions in Malignant Glioma

摘要 免疫疗法通过逆转细胞毒性抗肿瘤药物的免疫抑制，彻底改变了癌症治疗。 肿瘤CD 8+效应T细胞。然而，胶质母细胞瘤患者具有严重的淋巴细胞减少和免疫缺陷。 检查点抑制治疗不能恢复T细胞免疫功能。我们团队的广泛表征 已经证明，胶质母细胞瘤在其优先性方面与其他恶性肿瘤有根本的不同， 富集募集到肿瘤的先天免疫细胞，例如巨噬细胞和小胶质细胞 微环境这些先天免疫细胞是肿瘤支持性的。在基因工程小鼠模型中， 我们使用CD 8敲除（KO）背景重现了胶质母细胞瘤的GEMM，发现 PD-1表达巨噬细胞在鼠胶质瘤微环境中的显著富集-类似于 在人类胶质母细胞瘤患者中进行的观察。我们评估了抗PD-1抗体递送的效果， 在携带胶质母细胞瘤的野生型小鼠和CD 8 KO背景中静脉内， 即使在不存在CD 8效应T细胞的情况下也是有益的。外周单核细胞衍生的巨噬细胞和 在用抗PD-1 Ab处理的小鼠中，胶质母细胞瘤微环境内的常驻小胶质细胞减少。 因此，我们的总体研究假设是，抗PD-1发挥治疗性免疫调节作用， 在中枢神经系统（CNS）中通过先天性免疫抑制胶质母细胞瘤。该提案将解决多个 该领域的关键问题包括：1）抗PD-1抗体是否交叉进入CNS以发挥治疗作用; 2)除了CD 8 T细胞之外，哪些免疫细胞有助于这种药物的治疗效果; 3） 介导治疗效果的免疫细胞是由外周产生的，还是由免疫细胞固有的， CNS;以及4）胶质母细胞瘤免疫微环境如何响应治疗而改变？到 为了解决这些问题，我们将使用与人类神经胶质瘤非常相似的现代小鼠模型， 胶质母细胞瘤和操纵先天和适应性免疫系统，以剖析其影响和重要性， 在抗PD-1治疗的背景下，将使用人类受试者的数据进行验证 用抗PD-1治疗通过阐明抗PD-1治疗活性的机制作用，我们可以确定 胶质母细胞瘤患者的子集能够响应这种类型的策略。这是一个重要的领域 如果胶质母细胞瘤患者要从免疫治疗中受益，这些研究也可能揭示， 抗PD-1治疗对先天性和适应性免疫系统具有双重作用，并且当一个臂不 在操作中，该试剂将其调节特性切换到占优势的免疫臂。

ABSTRACT Immunotherapy has revolutionized cancer treatment by reversing the immune suppression of cytotoxic anti- tumor CD8+ effector T cells. However, glioblastoma patients have profound lymphopenia and immune checkpoint inhibition treatment does not restore T cell immune function. Extensive characterization by our group has demonstrated that glioblastoma is fundamentally different relative to other malignancies in its preferential enrichment of innate immune cells such as macrophages and microglia that are recruited to the tumor microenvironment. These innate immune cells are tumor supportive. In a genetically-engineered mouse model (GEMM) of glioblastoma we recapitulated lympophenia using a CD8 knockout (KO) background, and found marked enrichment of PD-1 expressing macrophages in the murine glioma microenvironment – similar to observations made in human glioblastoma patients. We evaluated the effect of anti-PD-1 Ab delivered intravenously in glioblastoma-bearing wild-type mice and in the CD8 KO background and found therapeutic benefit even in the absence of the CD8 effector T cell. Both peripheral monocyte-derived macrophages and resident microglia were reduced within the glioblastoma microenvironment in mice treated with the anti-PD-1 Ab. As such, our overall study hypothesis is that anti-PD-1 exerts therapeutic immune modulatory effects against glioblastoma through innate immunity in the central nervous system (CNS). This proposal will address multiple crucial questions to the field including: 1) Does the anti-PD-1 Ab cross into the CNS to exert a therapeutic effect; 2) what immune cells, other than the CD8 T cell, are contributing to the therapeutic effect of this agent; 3) are the immune cells that are mediating the therapeutic effect arising from the periphery or are they intrinsic to the CNS; and 4) how does the glioblastoma immune microenvironment change in response to treatment? To address these questions, we will use contemporary murine models of glioma that closely approximate human glioblastoma and manipulate both the innate and adaptive immune systems to dissect the impact and importance of each in the context of anti-PD-1 treatment. Validation will be carried out using data from human subjects treated with anti-PD-1. By clarifying the mechanistic role of anti-PD-1 therapeutic activity, we may identify the subset of glioblastoma patients that are capable of responding to this type of strategy. This is a significant area of unmet need if glioblastoma patients are to benefit from immunotherapy. These studies may also reveal that anti-PD-1 treatment has a dual role on both the innate and adaptive immune system and when one arm is not operational this agent toggles its modulatory properties to the dominant immune arm.