AHR-mediated immunosuppression in glioblastoma

项目总结 肿瘤相关巨噬细胞(TAM)在癌症的免疫反应中发挥着重要作用，但 控制TAMS和T细胞免疫的机制还不完全清楚。胶质母细胞瘤(GBM)是 成人最常见的原发脑瘤，尽管具有侵袭性，但中位生存期约为15个月 治疗。TAMs占基底膜浸润性细胞的30%以上。因此，靶向免疫 TAMS中的检查点被认为是治疗GBM和其他肿瘤的一种很有前途的免疫治疗方法。我们的 有资料表明，胶质瘤细胞产生的犬尿氨酸(Kyn)通过调节TAMs和T细胞免疫功能而发挥重要作用。 配体激活的转录因子芳香烃受体(AHR)。我们的数据表明：1) 在GBM患者和实验模型的TAM中，AHR和AHR驱动的基因表达上调。 2)TAMS中AHR缺失显著降低了肿瘤的生长 3)Kyn激活AHR可诱导转录因子Krüppel样蛋白的表达 第4因子(KLF4)参与调控的功能；4)AHR还可促进TAM、AND细胞中CD39的表达。 促进免疫抑制代谢物腺苷生成的胞外核苷酸酶；5)CD39 TAMS基因缺失改善GBM中肿瘤浸润性T淋巴细胞(TIL)功能障碍；6)一种新的大脑- 穿透性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，我们将TAMS中的AHR视为一个主调节因子，它对 肿瘤代谢物(如Kyn)抑制GBM特异性免疫。因此，我们假设TAMS中的AHR 限制肿瘤特异性免疫，是GBM潜在的免疫治疗靶点。我们的具体目标是：！ 具体目的1：明确AHR在TAMs转录调控中的作用。我们建议：1) 确定AHR是否通过调制KLF4和NF-kB信号来控制极化，以及2)定义 使用全群体和单细胞方法在TAMS中由AHR控制的转录程序。 特异性目的2：研究AHR驱动的CD39在TAM中的表达对TIL的调控。 我们建议：1)确定AHR诱导的TAM中CD39对GBM特异性T细胞的影响；2)确定 AHR/CD39轴通过腺苷的生成控制TIL，2)解剖AHR的相对贡献 CD39在小胶质细胞和外周巨噬细胞来源的TAMs中的表达与GBM的病理改变有关。 具体目的3：评估靶向AHR在GBM临床前模型中的治疗价值。 我们建议：1)研究AHR抑制对GBM TAMs的影响；2)分析AHR抑制的影响 对肿瘤特异性调节和效应T细胞的影响，以及3)评估AHR抑制剂对免疫的影响 系统中没有对胶质瘤肿瘤细胞的直接作用。 总而言之，该项目使用独特的实验系统来研究一种调节TAMS的新途径 以及GBM中的T细胞，是这种目前无法治愈的侵袭性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.