巨噬细胞对癌旁肝组织的改造及其促进肝癌肝内播散的机制研究

Intrahepatic dissemination is common in hepatocellular carcinoma (HCC), accounting for 80% post-operative recurrence. Peritumoral liver tissue is the most common site for intra-hepatic dissemination. We speculated that peritumoral liver tissue provided a suitable environment for tumor cell growth. However, the underlying mechanism is unclear. Our previous studies showed that abundant macrophages infiltrating the peritumoral liver tissue and the number of peritumoral macrophages was correlated with the incidence of intrahepatic dissemination. Besides, the M2 macrophages and its activator colony stimulating factor 1 (CSF1) in peritumoral liver tissue are indicative of intrahepatic dissemination and correlated with poor survival after curative surgery. It is unclear whether the infiltration of M2 macrophage is the precondition or consequence of the intrahepatic dissemination of HCC. Our recent research showed that tetrachloromethane induced liver fibrosis in mice liver with abundant M2 macrophage infiltration. After injection of liver cancer cells into the spleen, more tumor nodules were observed in the liver treated with tetrachloromethane compared with that treated with vehicle. We further assume that M2 macrophages infiltrate the peritumoral liver tissue before the intrahepatic dissemination of tumor cells, contributing to the pre-metastatic niche for HCC. We aimed at unveiling the mechanism of M2 macrophage in reforming the peritumoral liver tissue to facilitate the growth of intrahepatic dissemination of HCC and guiding potential adjuvant interventions in reducing the post-operative recurrences.

约80%的肝癌术后复发都发生在肝内，癌旁肝组织是肝内播散的好发部位。我们推测癌旁肝组织中存在适宜肝癌细胞生存的土壤，但其中的关键机制仍不清楚。我们的前期研究发现癌旁肝组织中存在较多的巨噬细胞浸润，其密度与肝癌肝内播散相关；我们还发现M2型巨噬细胞、以及促进巨噬细胞M2转化的分子（CSF1）等，在癌旁肝组织表达亦与肝癌肝内播散、术后不良预后相关。但M2型巨噬细胞募集是肝癌播散的前提还是结果目前尚不清楚。最近的实验研究发现，相比较溶媒处理的对照组，经四氯化碳处理的裸鼠肝脏出现了大量M2型巨噬细胞浸润；其后，在脾脏中注射肝癌细胞，可见四氯化碳处理的裸鼠肝脏内有更多的转移灶形成。我们推测，M2型巨噬细胞募集是在肝癌肝内播散灶之前形成，并构成了肝癌细胞转移的适宜土壤。本项目中，我们拟通过研究M2型巨噬细胞在肝组织内募集并促进肝癌肝内转移的机制，为肝癌术后复发的防治提供潜在的干预手段。

前期研究发现，癌旁肝组织中存在较多的巨噬细胞浸润，其密度与肝癌肝内播散相关；M2型巨噬细胞、以及促进巨噬细胞M2转化的分子(CSF1)等，在癌旁肝组织表达亦与肝癌肝内播散、术后不良预后相关。但M2型巨噬细胞募集是肝癌播散的前提还是结果目前尚不清楚。在本项目中，我们通过研究Siglec-10阳性巨噬细胞在肝组织内募集并促进肝癌进展的机制，为肝癌术后复发的防治提供潜在的干预手段。基于全外显子测序和流式细胞检测的数据显示，肝癌组织中Siglec-10阳性巨噬细胞中大量M2型标志分子及相关信号通路显着上调。Siglec-10阳性细胞在肿瘤间质组织高表达可提示肝癌患者术后的不良预后。进一步研究发现，Siglec-10阳性巨噬细胞高度浸润与肝癌中CD8阳性T细胞功能受损有关。用Siglec-10 Fc竞争性阻断Siglec-10通路，会降低巨噬细胞上免疫抑制性分子的表达，并增加CD8阳性T细胞的细胞毒性作用。我们的结果表明，Siglec-10阳性巨噬细胞可造成抑制性的肿瘤免疫微环境。靶向Siglec-10相关通路可逆转肿瘤相关巨噬细胞的功能表型，重激活抗肿瘤免疫反应，在肝癌免疫治疗领域具有良好的干预价值。