P2X7介导的巨噬细胞免疫调控在肺癌发生、发展中的功能和机制研究

Tumor-associated macrophages (TAMs) form a polarization state that promotes tumor progression and immune escape under the complex regulation of tumor immune microenvironment. Extracellular nucleotides are a kind of important immune microenvironment regulatory molecules, but the specific function and mechanism of nucleotides and their receptors in the regulation of TAMs have yet to be further investigated. Our previous study showed that nucleotide ATP and its receptor P2X7 played vital roles in anti-infectious diseases by regulating macrophages. Meanwhile, P2X7 was highly expressed in tumor tissues and TAMs, which is positively correlated with poor prognosis of lung cancer patients. Furthermore, urethane-induced lung cancer and subcutaneously transplanted tumors were significantly inhibited in P2X7 knockout mice as well as M2-type macrophages were obviously reduced, suggesting that P2X7 was closely related to the polarization function of TAMs and tumors. This study intends to investigate the correlation between the high expression of P2X7 in lung cancer and immune functions such as TAMs polarization, as well as the specific function and mechanism of P2X7 in the occurrence and development of lung cancer. Therefore, we propose to systematically explore the dominant role of P2X7-mediated macrophage immunoregulation in lung cancer formation and progression in animal, cellular and molecular level. Besides, we will identify the potential value of P2X7 as a new immunotherapy target, so as to provide new ideas and theoretical basis for the immunotherapy strategy of lung cancer.

肿瘤相关巨噬细胞(TAMs)在肿瘤免疫微环境的复杂调控下形成促进肿瘤生长和免疫逃逸的极化状态，其中胞外核苷酸是一类重要的免疫微环境调控分子，但是核苷酸及其受体调控TAMs的具体功能和机制尚待阐明。我们前期发现：核苷酸ATP及其受体P2X7调控巨噬细胞在抗感染疾病中发挥重要作用，同时P2X7在肿瘤组织和TAMs中呈现高表达，与肺癌病人的不良预后呈正相关；在P2X7敲除小鼠体内，乌拉坦诱导的肺癌和皮下移植瘤受到明显抑制，且M2型巨噬细胞比例显著降低，提示P2X7与TAMs极化功能及肿瘤密切相关。本课题拟探讨肺癌上P2X7的高表达与TAMs极化等免疫功能的相互关系及其调控TAMs在肺癌发生、发展中的具体功能和机制。即从动物整体、细胞和分子三个层面系统探讨P2X7介导的巨噬细胞免疫调控在肺癌发展过程中的作用和分子机制，明确其作为新型免疫治疗靶点的潜在价值，为肺癌免疫治疗策略提供新的思路和理论依据。

肿瘤相关巨噬细胞(TAMs)在肿瘤免疫微环境的复杂调控下形成促进肿瘤生长和免疫逃逸的极化状态，其中胞外核苷酸是一类重要的免疫微环境调控分子，但是核苷酸ATP及其主要受体P2X7调控TAMs的具体功能和机制尚待阐明。我们从动物整体 、细胞和分子三个层面对P2X7介导的巨噬细胞在肿瘤免疫调控方面展开了系统研究。首先，我们通过流式细胞术对P2X7在肿瘤组织中各类免疫细胞上的表达进行检测和分析，结果发现P2X7主要在TAMs中高表达，同时我们通过Q-PCR和WB也验证了其确实在TAMs和IL-4诱导的M2型巨噬细胞上显著高表达。接着，我们在体外对P2X7调控巨噬细胞的极化和吞噬功能进行检测，结果显示敲除或抑制P2X7显著下调Arg1、CD206等M2型巨噬细胞标志基因的表达，而不影响M1型标志基因的表达和其对肿瘤细胞的吞噬功能。进一步我们在小鼠体内建立了一系列肿瘤模型，结果发现P2X7缺失或者被抑制剂封闭之后，显著抑制小鼠皮下移植瘤、肺原位肿瘤以及乌拉坦诱导的肺癌发生，并且提高了小鼠的生存期。同时通过生物信息学分析也发现P2X7与肺癌患者的不良预后呈正相关。接着，我们对P2X7介导TAMs调控肿瘤微环境的功能和分子机制进行了详细分析，结果表明P2X7缺失之后减弱了TAMs对肿瘤细胞的促增殖、血管生成以及CD8+ T细胞的活性抑制作用；P2X7缺失之后主要是通过下调STAT6的磷酸化水平以及IRF4的表达从而抑制TAMs向M2型极化，而不参与对STAT3、CREB、PPARγ、PI3K等相关信号通路的调控。最后，我们探究了P2X7作为肿瘤免疫治疗靶点的潜在价值，发现抑制P2X7可以有效协同提高化疗药物顺铂和免疫检查点阻断剂anti-PD-1抗体的治疗效果，改善了其临床耐药和不明感问题。我们的研究为基于嘌呤受体信号和TAMs的抗肿瘤药物研发和临床肿瘤治疗奠定了理论基础。