Chitinase-3-like-1 mediated immunosuppression in Glioblastoma

项目摘要 胶质母细胞瘤（GBM）是最常见和致命的脑肿瘤，中位生存率约为15个月 尽管进行了包括免疫疗法在内的强化多模式治疗。GBM是高度免疫抑制的， 因为胶质瘤细胞通过修饰免疫球蛋白而逃避有效的抗肿瘤免疫， 肿瘤微环境（TME）。由于肿瘤细胞和周围TME的多样性和可塑性， 对GBM免疫逃避机制的理解仍然是难以捉摸的。我们的长期目标是解剖 癌细胞内在机制，重新编程GBM的TME，以开发有效的治疗方法。 我们最近鉴定了几丁质酶-3-样-1（CHI3L1），一种在GBM中高度表达和分泌的糖蛋白， 候选人介导免疫逃避。我们的中心发现是，在同基因GBM中沉默Chi3l1表达， 小鼠模型导致肿瘤浸润淋巴细胞（TIL）增加，肿瘤大小减小， 动物存活率，这是逆转过表达的CHI3L1。我们发现的潜在机制是 半乳糖凝集素-3（Gal3）是β-半乳糖苷结合凝集素家族的成员， （Gal3BP），一种分泌的糖蛋白，与CHI3L1上相同的结合基序竞争性相互作用，导致 促肿瘤M2样与抗肿瘤M1样骨髓源性巨噬细胞的选择性积聚 （BMDM）和常驻小胶质细胞（MG）。本申请的总体目标是确定 CHI3L1重置肿瘤相关巨噬细胞（TAM）（包括BMDM）的分子机制， MG，GBM TME的主要成分，并干预这一过程用于治疗目的。中央 假设CHI3L1与Gal3和Gal3BP结合复合物，重编程TAM募集，极化， 和细胞因子产生，其失调抗肿瘤TIL浸润和活化以促进GBM生长， 进展和对免疫疗法的抗性。为了验证我们的假设，我们建议1）描述机制 CHI3L1结合复合物在TAM募集和极化中的作用; 2）破译CHI3L1-重编程 TAM介导GBM免疫抑制，和3）评估破坏CHI3L1结合的临床前功效 复合物促进GBM对免疫检查点阻断的应答。为了实现这些目标，我们将 采用体外和体内获得/丧失功能的方法来阐明CHI3L1结合复合物如何调节 TAM和TIL在免疫逃避中的作用为了推进转化研究的潜在方向，我们将测试一个 新开发的肽单独和与免疫检查点抑制剂联合治疗临床前 胶质瘤小鼠模型。本申请中提出的研究具有创新性，因为它基于一种新的 CHI3L1结合复合物调节GBM免疫抑制的机制。拟议的研究是 重要的是，它有望为开发有效的治疗方法提供强有力的科学依据。 对于GBM患者。最终，这些知识有可能为癌症提供新的机会。 治疗

Project Summary Glioblastoma (GBM) is the most common and lethal brain tumor with a median survival rate of about 15 months despite intensive multimodal treatment including immunotherapy. GBM is highly immunosuppressive and resistant to immunotherapy because glioma cells escape from effective antitumor immunity by modifying the tumor microenvironment (TME). Owing to the diversity and plasticity of tumor cells and the surrounding TME, understanding the mechanisms of immune evasion by GBM remains elusive. Our long-term goal is to dissect cancer-cell-intrinsic mechanisms that reprogram the TME of GBM for the development of effective treatments. We recently identified Chitinase-3-like-1 (CHI3L1), a highly expressed and secreted glycoprotein in GBM as a candidate to mediate immune evasion. Our central finding is that silencing Chi3l1 expression in syngeneic GBM mouse models results in increased tumor-infiltrating lymphocytes (TILs), tumor size reduction, and improved animal survival, which is reversed by overexpression of CHI3L1. The underlying mechanism we discovered is that Galectin-3 (Gal3), a member of the β-galactoside-binding lectin family, and Galectin-3 binding protein (Gal3BP), a secreted glycoprotein, interact competitively with the same binding motif on CHI3L1, leading to selective accumulation of protumor M2-like versus antitumor M1-like bone marrow-derived macrophages (BMDMs) and resident microglia (MG). The overall objective in this application is to determine the detailed molecular mechanisms whereby CHI3L1 resets tumor-associated macrophages (TAMs) including BMDMs and MG, a main component of the GBM TME, and to intervene in this process for therapeutic purposes. The central hypothesis is that CHI3L1-binding complexes with Gal3 and Gal3BP, reprogram TAM recruitment, polarization, and cytokine production, which dysregulates antitumor TIL infiltration and activation to facilitate GBM growth, progression, and resistance to immunotherapy. To test our hypothesis, we propose to 1) delineate mechanisms of CHI3L1-binding complexes in TAM recruitment and polarization; 2) decipher how CHI3L1-reprogrammed TAMs mediate GBM immunosuppression, and 3) assess the preclinical efficacy of disrupting CHI3L1-binding complexes in promoting GBM response to immune checkpoint blockade. To accomplish these aims, we will employ in vitro and in vivo gain/loss-of-function approaches to elucidate how CHI3L1-binding complexes regulate the TAMs and TILs in immune evasion. To advance a potential direction for translational research, we will test a newly-developed peptide alone and in combination therapy with immune checkpoint inhibitors in preclinical glioma mouse models. The research proposed in this application is innovative because it is based on a new mechanism of CHI3L1-binding complexes regulating GBM immunosuppression. The proposed research is significant because it is expected to provide a strong scientific rationale for the development of effective therapies for GBM patients. Ultimately, such knowledge has the potential of offering new opportunities for cancer treatment.