Role of myeloid-derived suppressor cells in local and systemic immunosuppression in glioblastoma

项目摘要：胶质母细胞瘤(GBM)是最常见的原发恶性脑肿瘤，中位数为 存活时间长达20个月。男性的GBM发病率是女性的1.6倍，情况更糟 疾病后果。目前处于临床试验阶段的免疫疗法在改善病情方面成效有限。 病人的结果。促进肿瘤进展、限制抗肿瘤免疫抑制的微环境 肿瘤免疫反应可能是治疗抵抗的基础。虽然髓系细胞的积聚 抑制细胞(MDSCs)在这种免疫抑制环境的建立中起着关键作用 单个MDSC亚群促进肿瘤发生和调控的机制仍不明确。 我们先前证明单核细胞MDSCs(MMDSCs)在男性肿瘤中有较高的浸润率。 临床前模型和患者样本。相反，粒细胞MDSCs(GMDSCs)在外周扩张 雌性动物模型的循环和gMDSC基因特征与雌性预后不良有关 病人。MDSC亚群的这种变异也提示了对氟达拉滨和 临床前模型中的抗IL-1β。最近，我们观察到mMDSCs和gMDSCs具有明显的 表观遗传景观，这也是由生物性别决定的。虽然这突显了 MDSC亚群活性的表观遗传调节，对驱动不同MDSC的机制认识有限 子集函数。我们的初步结果表明，补体途径可能是其中一种机制。 作为补体成分，1q(C1q)在GMDSCs中高表达，在雌性中升高。基于这些 观察到，我们假设C1q的表观遗传调控影响MDSC亚群的性别特异性行为 MDSCs的表观遗传重新编程将提高T细胞激活策略的效率。特定目标 1将检验这样一种假设，即MDSC亚群的独特表观遗传特征使它们容易患上 不同的组蛋白修饰物可以与检查点调节剂结合。次级目标A将审查 组蛋白赖氨酸去甲基酶抑制剂在体内外对MDSC活性的影响，而亚靶蛋白1B将 试图通过将铅抑制剂与抗PD-1、抗CTLA-1结合来实现持久的抗肿瘤免疫反应 4、抗OX40。特定目标2将检验C1q基因座在以下情况下可区分访问的假设 男性MDSC亚群与女性MDSC亚群。子目标2A将使用ATAC-SEQ和CUT&RUN来评估表观遗传学 基于差异组蛋白赖氨酸的补体蛋白和特异组蛋白标记的分布 去甲基酶表达谱。SubAim 2B将使用药物抑制剂来测试 组蛋白赖氨酸去甲基酶对补体的调节。这些研究为…的发展奠定了基础 用于GBM免疫治疗的表观遗传修饰剂通过解决抗肿瘤免疫的变化，重新定位 药物，并确定有针对性的途径。这些结果广泛适用于其他癌症，并可能导致 先进的治疗机会和改善的患者结局。

PROJECT SUMMARY: Glioblastoma (GBM) is the most common primary malignant brain tumor, with a median survival of up to 20 months. Males have a 1.6-fold higher incidence of GBM compared to females and worse disease outcomes. Immunotherapies, which are currently in clinical trials, have had limited success in improving patient outcomes. An immunosuppressive microenvironment facilitating tumor progression and restricting anti- tumor immune response likely underlies therapeutic resistance. Although the accumulation of myeloid-derived suppressor cells (MDSCs) plays a critical role in the establishment of this immunosuppressive milieu, the mechanisms by which individual MDSC subsets promote tumorigenesis and are regulated remain poorly defined. We previously demonstrated that monocytic MDSCs (mMDSCs) infiltrated male tumors at higher rates in preclinical models and patient specimens. In contrast, granulocytic MDSCs (gMDSCs) expand in the peripheral circulation of female animal models and the gMDSC gene signature is associated with poor prognosis in female patients. This variation in MDSC subsets also informed sex-specific therapeutic responses to fludarabine and anti-IL-1β in preclinical models. More recently, we observed that mMDSCs and gMDSCs have a distinct epigenetic landscape, which is also informed by biological sex. While this highlights the potential role of epigenetic regulation of MDSC subset activity, there is limited insight into the mechanisms driving distinct MDSC subset functions. Our preliminary results suggested that the complement pathway could be one such mechanism as complement component 1q (C1q) was highly expressed by gMDSCs and elevated in females. Based on these observations, we hypothesize that epigenetic regulation of C1q informs sex-specific behavior of MDSC subsets and epigenetic reprogramming of MDSCs will improve the efficacy of T cell-activating strategies. Specific Aim 1 will test the hypothesis that the unique epigenetic signatures of MDSC subsets make them susceptible to different histone modifiers that can be combined with checkpoint modulators. Sub-Aim 1A will examine the efficacy of histone lysine demethylase inhibitors on MDSC activity in vitro and in vivo, while Sub-Aim 1B will attempt to achieve durable anti-tumor immune response by combining lead inhibitors with anti-PD-1, anti-CTLA- 4, and anti-OX40. Specific Aim 2 will test the hypothesis that the C1q locus is differentially accessible between male versus female MDSC subsets. Sub-Aim 2A will use ATAC-seq and CUT & RUN to evaluate the epigenetic landscape of complement proteins and specific histone mark occupancy based on the differential histone lysine demethylase expression profile. Sub Aim 2B will use pharmacological inhibitors to test the sex-specific effect of histone lysine demethylases on complement regulation. These studies lay the foundation for the development of epigenetic modifiers for GBM immunotherapies by addressing variations in anti-tumor immunity, repurposing drugs, and defining targetable pathways. These results are broadly applicable to other cancers and can lead to advanced treatment opportunities and improved patient outcomes.