清除Gr1+CD11b+髓源性抑制细胞联合微波消融瘤内注射免疫微球减少肝癌消融术后复发的研究

Thermal ablation is an important mordality for unresectable small hepatocellular carcinoma, but the recurrence rate is still high. Our previous study showed that microwave ablation could induce antitumor immunity by providing immunogenic tumor antigens, while combined with intratumoral injection of GM-CSF and IL-2 microparticles, the combined therapy could enhance the efficacy of tumor specific CTLs, but not sufficient to suppress distant tumor growth. There are evidences that myeloid derived suppressor cells (MDSCs) in tumor microenvironment could induce regulatory T cells (Treg) accumulation and anergy of effective T cells and NK cells, hence suppress antitumor immunity. In our study, we use Gemcitabine to deplete MDSCs and microwave ablation with intratumoral injection of cytokine microparticles to enhance the antitumor immunity while reversing the immune suppressive microenvironment in order to explore a new method for controlling post ablation recurrence. Tumor growth and mice survival are recorded to prove the efficiency of the new therapy. The numeric and functional alterations of lymphocytes, natural killer cells and MDSCs in both spleen and tumor tissues are tested to investigate the underlying mechanisms.

热消融是原发性肝癌非外科治疗的重要手段，但术后复发率高。我们既往研究发现，微波消融能为诱导抗肝癌免疫反应提供有效抗原，辅以瘤内注射GM-CSF/IL-2免疫缓释微球可以诱导肿瘤特异性CTLs，同时降低肿瘤微环境中起免疫抑制作用的调节性T细胞（Treg）数量，但不足以抑制远处已存在肿瘤的生长。有研究表明肿瘤微环境中髓源性抑制细胞(MDSCs)可促进Treg在肿瘤处聚集、同时抑制效应T细胞和NK细胞的功能，从而抑制抗肿瘤免疫。本研究中，我们拟采用Gemcitabine选择性清除体内MDSCs逆转免疫抑制微环境，同时用微波消融瘤内注射免疫微球，诱导抗肿瘤主动免疫，通过观察肿瘤生长情况和小鼠生存率探讨该方法治疗和预防肿瘤消融后复发的疗效。检测小鼠脾脏、肿瘤组织中淋巴细胞、NK细胞及MDSCs表型和功能状态变化及细胞因子分泌的改变，阐明抗肿瘤效应可能的机制，探索一种预防和治疗肝癌消融术后复发的新途径

局部热消融是治疗原发性肝癌的重要方式，但消融后肿瘤5年复发率高达70%，严重制约了其临床应用和肝癌整体疗效。至今仍无有效手段干预消融术后肿瘤复发。本项目在多学科综合治疗模式的理念指导下，结合当前研究热点，一方面继续通过构建小鼠皮下肝癌移植瘤消融模型，制作热消融原位疫苗，并联合清除髓源性抑制细胞，观察对抑制肿瘤复发的作用，在此基础上进一步初步探究热消融后免疫机制，解除抑制性免疫微环境，筛选肿瘤新生抗原，以期充分激发消融诱导的抗肿瘤免疫反应，减少肿瘤复发，提高疗效；另一方面，积极探究肝癌消融后高复发率的分子机制，筛选出多个肝癌生长相关的敏感分子及调控通路，为治疗新靶点的开发提供了重要的线索，并初步研发了高特异靶向肝癌细胞的纳米复合物，为阻断肝癌消融后复发提供了新的治疗策略和手段。