Targeting GPR84 to Overcome Macrophage Mediated Resistance to Immunotherapy

项目摘要 免疫检查点阻断(ICB)在超过25种肿瘤中产生了非凡的临床反应 类型。然而，由于免疫抑制疗法，只有一小部分患者从这种疗法中受益。 MOR微环境(TME)。作为TME的主要成分之一，肿瘤相关巨噬细胞 (TAMs)通常对肿瘤杀伤T细胞具有深刻的抑制活性，并促进肿瘤逃逸 来自免疫疗法。临床结果表明，抑制性促肿瘤TAMs的存在 与接受免疫治疗的膀胱癌患者存活率降低有关。由于具有可塑性， 巨噬细胞，兴奋一直在增长，以重塑促致癌的TAMs，转向抗致癌 表型以激发对癌症的免疫力。新出现的证据表明，这一宏观经济过程-- 噬菌体极化不可避免地受到TME中代谢产物的影响，如游离脂肪酸(FFA)。缺乏 有关FFA信号在巨噬细胞中的作用的数据阻止了我们设计一种优雅的方法来重新 极化，培养更好的抗肿瘤T细胞反应。我们建议解剖分子基础 FFA介导的TAMS分化信号通路及其在抵抗PD-1阻断中的作用 用来恢复对ICB治疗的敏感性。我们对已公布的数据集的分析显示，TAMS来自 人类膀胱肿瘤独特地表达高水平的脂肪酸受体--G蛋白偶联受体 84(GPR84)。这些表达GPR84的细胞表现出丰富的抗肿瘤功能。 与他们的同行相比有所减少。进一步分析表明，GPR84的表达与 膀胱癌患者的生存期更长。我们的工作表明，GPR84的基因消融导致增强 通过激活CCAAT/增强子结合蛋白β产生包括精氨酸酶1在内的抑制分子 (C/eBPβ)。相比之下，GPR84被其激动剂6-非统激活后，可以重新编程促肿瘤的巨噬细胞 产生抗肿瘤标志性分子，如肿瘤坏死因子-α(肿瘤坏死因子α)。从机械上讲，我们 发现GPR84可增强核因子-kappaB(NF-κB)的活性，从而促进肿瘤坏死因子α的产生。 中心假说：GPR84是决定宏观调控功能的代谢信号检查点。 噬菌体通过限制免疫抑制而促进免疫刺激表型。治疗 GPR84激动剂显著抑制肿瘤生长并增强抗PD-1单抗的抗肿瘤效果 MB49膀胱癌模型的治疗。目标1：确定GPR84的缺失是否促进了极化- 免疫抑制药物TAMS的治疗。目的2：剖析GPR84的分子和表观遗传学机制 信号促进巨噬细胞的免疫刺激表型。目标3：确定目标是否 GPR84介导的巨噬细胞复极增强ICB的抗肿瘤效应。结果将通知 通过代谢操作重塑免疫抑制TME的有前景的治疗方法的研究进展 从而恢复膀胱癌患者对PD-1阻断的反应性。

Project Summary Immune checkpoint blockade (ICB) has produced extraordinary clinical responses in more than 25 tumor types. However, only a small number of patients benefit from this therapy owing to the immunosuppressive tu- mor microenvironment (TME). As one of the major components of the TME, tumor-associated macrophages (TAMs) usually possess profound inhibitory activity against tumor-killing T cells and facilitate tumor escape from immunotherapy. Clinical findings have shown that the presence of suppressive pro-tumorigenic TAMs correlates with reduced survival in bladder cancer patients treated with immunotherapy. Due to the plasticity of macrophages, excitement has been growing to reshape the pro-tumorigenic TAMs toward the anti-tumorigenic phenotype to stimulate the immunity against cancer. Emerging evidence reveals that this process of macro- phage polarization is inextricably affected by metabolites in the TME, such as free fatty acid (FFA). Lack of data regarding the role of FFA signals in macrophages prevents us from designing an elegant approach to re- polarizing TAM to foster a better anti-tumor T cell response. We propose to dissect the molecular basis of the FFA-mediated signal pathway in TAMs differentiation and its role in resistance to PD-1 blockade, which can be leveraged to restore sensitivity to ICB therapy. Our analysis of published datasets revealed that TAMs from human bladder tumors uniquely express elevated levels of a fatty acid receptor, G Protein-Coupled Receptor 84 (GPR84). These GPR84 expressing cells exhibited enriched hallmarks of anti-tumorigenic function com- pared to their counterpart. Further analysis reveals that expression of GPR84 significantly correlates with longer survival in bladder cancer patients. Our work shows that genetic ablation of GPR84 leads to enhanced production of inhibitory molecules including Arginase 1 via activation of CCAAT/enhancer-binding protein beta (C/EBPβ). By contrast, GPR84 activation by its agonist 6-OAU can reprogram pro-tumorigenic macrophages to produce anti-tumorigenic signature molecules, such as tumor necrosis factor-α (TNFα). Mechanistically, we found that GPR84 potentiates the activity of Nuclear factor kappa B (NF-κB) to enhance TNFα production. Central hypothesis: GPR84 serves as a metabolic signaling checkpoint for determining the function of macro- phage by restricting the immunosuppressive while promoting the immune-stimulating phenotype. Treatment with GPR84 agonists significantly retards tumor growth and increases the anti-tumor efficacy of anti-PD-1 mAb therapy in a MB49 bladder cancer model. Aim 1: Determine whether the lack of GPR84 promotes the polariza- tion of immunosuppressive TAMs. Aim 2: Dissect the molecular and epigenetic mechanisms by which GPR84 signaling promotes an immune-stimulating phenotype in macrophages. Aim 3: Determine whether targeting GPR84-mediated macrophage repolarization enhances the anti-tumor efficacy of ICB. Results will inform the development of promising treatments to reshape immunosuppressive TME through manipulation of metabolic signaling, and thereby restore responsiveness to PD-1 blockade for bladder cancer patients.