AHR-mediated immunosuppression in glioblastoma

项目摘要 肿瘤相关巨噬细胞（TAM）在对癌症的免疫应答中起重要作用，但肿瘤相关巨噬细胞（TAM）在肿瘤的免疫应答中起重要作用。 控制TAM和T细胞免疫的机制尚未完全了解。胶质母细胞瘤（GBM）是 成人中最常见的原发性脑肿瘤，尽管具有侵袭性，但中位生存期约为15个月。 治疗TAM占GBM中浸润细胞的30%以上。因此，靶向免疫 TAM中的检查点被认为是GBM和其他肿瘤的有希望的免疫抑制方法。我们 数据表明，由神经胶质瘤细胞产生的犬尿氨酸（Kyn）控制TAM和T细胞免疫， 配体激活的转录因子芳烃受体（AHR）。我们的数据表明：1） AHR和AHR驱动基因的表达在GBM患者和实验模型的TAM中上调， 并且与患者存活率显著相关; 2）TAM中的AHR缺失显著降低了肿瘤的生长， 实验性GBM; 3）Kyn激活AHR诱导Krüppel样转录因子的表达 4）AHR还驱动TAM中CD 39的表达， 促进免疫抑制代谢物腺苷产生的外核苷酸酶; 5）CD 39 TAMs的缺失改善GBM中的肿瘤浸润性T淋巴细胞（TIL）功能障碍; 6）一种新的脑- 渗透性AHR拮抗剂和候选免疫检查点抑制剂抑制几种肿瘤的生长 包括GBM。基于这些发现，我们认为TAM中的AHR是一个主要的调节器， 肿瘤治疗（例如，Kyn）抑制GBM特异性免疫。因此，我们假设TAM中的AHR 限制了肿瘤特异性免疫，是GBM的潜在免疫靶点。我们的具体目标是：！ 具体目标1：确定AHR在TAM转录调控中的作用。我们建议：1） 确定AHR是否通过KLF 4和NF-kB信号传导的调制来控制TAM极化，以及2）定义 使用全群体和单细胞方法在TAM中由AHR控制的转录程序。 具体目的2：研究TAM中AHR驱动的CD 39表达对TIL的控制。 我们建议：1）确定TAM中AHR诱导的CD 39对GBM特异性T细胞的影响，2）确定是否 AHR/CD 39轴通过腺苷生成控制TIL，和2）剖析AHR的相对贡献 和CD 39在小胶质细胞和外周巨噬细胞衍生的TAM中对GBM病理的影响。 具体目标3：在GBM临床前模型中评价靶向AHR的治疗价值。 本研究拟：1）研究AHR抑制对GBM TAM的影响，2）分析AHR抑制对GBM TAM的影响 3）评估AHR抑制剂对肿瘤特异性调节性和效应T细胞的影响， 系统在没有对胶质瘤肿瘤细胞的直接作用的情况下。 总之，该项目使用独特的实验系统来研究调节TAMs的新途径 和T细胞，并且是这种侵袭性和目前无法治愈的疾病的潜在治疗靶点。

PROJECT SUMMARY Tumor-associated macrophages (TAMs) play an important role in the immune response to cancer, but the mechanisms that control TAMs and T-cell immunity are not completely understood. Glioblastoma (GBM) is the most common primary brain tumor in adults, with a median survival of ~15 months despite aggressive treatment. TAMs constitute more than 30% of infiltrating cells in GBM. Consequently, targeting immune checkpoints in TAMs is considered a promising immunotherapeutic approach for GBM and other tumors. Our data indicate that kynurenine (Kyn) produced by glioma cells controls TAMs and T-cell immunity through the ligand-activated transcription factor aryl hydrocarbon receptor (AHR). Our data demonstrate that: 1) the expression of AHR and AHR-driven genes is upregulated in TAMs in GBM patients and experimental models, and is significantly linked to patient survival; 2) AHR deletion in TAMs significantly decreases tumor growth in experimental GBM; 3) AHR activation by Kyn induces the expression of the transcription factor Krüppel-like factor 4 (KLF4) and controls TAM function; 4) AHR also drives the expression of CD39 in TAMs, an ectonucleotidase that promotes the generation of the immunosuppressive metabolite adenosine; 5) CD39 deletion in TAMs ameliorates tumor infiltrating T-lymphocyte (TIL) dysfunction in GBM; 6) A new brain- penetrant AHR antagonist and candidate immune checkpoint inhibitor suppresses growth of several tumors including GBM. Based on these findings, we view AHR in TAMs as a master regulator that responds to oncometabolites (e.g., Kyn) to suppress GBM-specific immunity. Therefore, we hypothesize that AHR in TAMs limits tumor-specific immunity and is a potential immunotherapeutic target for GBM. Our specific aims are:! SPECIFIC AIM 1: Define the role of AHR in the transcriptional control of TAMs. We propose to: 1) Determine if AHR controls TAM polarization via modulation of KLF4 and NF-kB signaling, and 2) Define the transcriptional programs controlled by AHR in TAMs using whole population and single cell approaches. SPECIFIC AIM 2: Study the control of TILs by AHR-driven CD39 expression in TAMs. We propose to: 1) Define the effects of AHR-induced CD39 in TAMs on GBM-specific T cells, 2) Determine if the AHR/CD39 axis controls TILs via adenosine generation, and 2) Dissect the relative contribution of AHR and CD39 in microglia- and peripheral macrophage-derived TAMs to GBM pathology. SPECIFIC AIM 3: Evaluate the therapeutic value of targeting AHR in a GBM preclinical model. We propose to: 1) Study the effects of AHR inhibition on GBM TAMs, 2) Analyze the effects of AHR inhibition on tumor-specific regulatory and effector T cells, and 3) Evaluate the effects of an AHR inhibitor on the immune system in the absence of a direct effect on glioma tumor cells. IN SUMMARY, this project uses unique experimental systems to study a novel pathway that regulates TAMs and T cells in GBM and is a potential therapeutic target for this aggressive and currently incurable disease.