CCR6/CCL20轴介导外周血FoxP3+调节性T细胞向肝细胞肝癌组织迁移的机制研究及临床意义

Regulatory T cell (Treg)-mediated immunosuppression is one of the crucial tumor immune-evasion mechanisms and the main obstacle for successful tumor immunotherapy. Our previous results showed that intratumoral enrichment of Tregs was mainly associated with CCR6/CCL20 axis-mediated migration of circulating Tregs into tumor tissue, and predicted poor prognosis in patients with hepatocellular carcinoma (HCC). However, the mechanism of CCR6/CCL20 axis-mediated selective migration is largely unknown, and the clinical significance of increased intratumoral Tregs needs to be investigated further. Therefore, we want to explore the mechanism by which the CCR6/CCL20 axis mediates the migration of circulating Tregs into tumor tissue and its clinical significance in multiple levels:in the RNA level, detecting and comparing the expression of different genes in different districts of tumor tissue, then constructing biomolecular network to guide the subsequent research; in the protein level, investigating the exact mechanism of CCR6/CCL20 axis-mediated migration with molecular biological and immunological methods; in microenvironmental level, vadilating and evaluating the efficacy in the treatment of hepatocellular in a mouce HCC model; in clinical aspect, further investgating the association of Treg subsets and immune-gene signature with the prognoses of HCC patients, establishing a “immune score” system. Our results will clarify the mechanism of intratumoral enrichment of Tregs by CCR6/CCL20 axis in the microenvironment of HCC, and provide a new thought and drug target for HCC treatment.

调节性T细胞（Tregs）介导的免疫抑制反应是肿瘤免疫逃避的关键机制和免疫治疗失败的主要原因。我们已发现：肝癌组织内Tregs的富集主要与CCR6/CCL20轴介导患者外周血Tregs向肿瘤迁移相关，并预示不良预后，但该迁移过程的具体机制尚未完全明确；此外，肿瘤内Tregs增加的临床意义有待进一步深化。为此，本项目拟从多个层面和角度进行深化和拓展：在RNA水平，通过对肿瘤内不同区域不同基因表达的比较和相关性分析，建立生物分子网络，为后续研究确立方向；在蛋白水平，通过分子生物学和免疫学方法阐明CCR6/CCL20轴介导外周血FoxP3+Tregs选择性迁移的具体机制；微环境水平，建立肝癌小鼠模型，验证并评估趋化信号阻断对肝癌治疗的效果；从临床角度，进一步探讨Tregs亚群、免疫标记组合与肝癌患者预后的相关性，建立“免疫评分系统”。该研究将为肝细胞肝癌的综合治疗提供一种新的思路和药物作用靶点。

调节性T细胞（Tregs）介导的免疫抑制反应是肿瘤免疫逃避的关键机制和免疫治疗取得成功的主要障碍。Tregs在体内免疫功能的发挥不但与细胞自身的免疫抑制能力相关，还取决于它们在组织内的合理定位。本研究采用生物信息学、免疫学和分子生物学等技术，明确CCR6/CCL20介导外周血Tregs向肝细胞肝癌组织迁移的具体机制：① 外周血进入肿瘤组织后，肿瘤组织内肝癌细胞，尤其肿瘤干细胞（CD133+和CD90+），和巨噬细胞（CD68+）通过大量分泌趋化因子CCL20，介导外周血中CCR6高表达的Tregs细胞向肿瘤巢中迁移，进入肿瘤组织迁移至高表达粘附分子（ALCAM）和整合素（ITGAX和ITGAD）的肝癌细胞周围，发挥Tregs的免疫抑制作用，促进肿瘤进展；② 除了CCR6/CCL20信号通路外，CXCR3/CXCL10信号通路也是介导外周血Tregs向肝癌组织迁移的重要机制，并与CCR6/CCL20信号通路起协同作用。此外，我们还发现肿瘤微环境内趋化因子、粘附分子和整合素的表达与患者的预后相关：① 肝癌患者术后预后好的患者CCL20、CXCL0、ALCAM、ITGAX和ITGAD等一系列趋化相关的蛋白的表达显著低于预后差的患者； ② CCL20、CXCL0、ALCAM、ITGAX和ITGAD等一系列趋化相关的蛋白的组合表达与FoxP3的结合，能较好的预测肝细胞肝癌患者术后预后。本研究为肝细胞肝癌的综合治疗提供一种新的思路和药物作用新靶点。