Key Laboratory of Infection and Immunity of Shandong Province, Department of Immunology, School of Basic Medical Science, Shandong University, Jinan, China.
Department of Pathology, Qilu Hospital of Shandong University, Jinan, China.
Front Immunol. 2019 Jul 16;10:1643. doi: 10.3389/fimmu.2019.01643. eCollection 2019.
Hepatocellular carcinoma (HCC) is a prototype of inflammation-related cancer, harboring M1-like and M2-like tumor-associated macrophages. M1 macrophages are thought to be tumoricidal, but some studies report its pro-tumor role. The programmed cell death-ligand (PD-L) 1 expressed in HCC cells is a critical checkpoint molecule to mediate immune escape of HCC. The PD-L1 expression in HCC cells is inducible. In the present study, we ask whether M1 macrophages induce the expression of PD-L1 in HCC cells. First, an association between M1 macrophage infiltration and PD-L1 expression in HCC tissues was determined by bioinformatics and immunohistochemistry experiments. The enrichment score of M1 macrophages was correlated to PD-L1 expression in 90 HCC samples from GEO database. Besides, infiltration of CD68+HLA-DR+ M1-like macrophages correlated with PD-L1 expression level in HCC cells. Moreover, M1-conditioned media was prepared from M1 macrophages derived from THP-1 cell, RAW264.7 cell or murine bone marrow. These supernatants induced expression of PD-L1 in HCC cells. Furthermore, inflammatory cytokine IL-1β in the supernatants was identified to account for the inducible PD-L1 expression by siRNA assay and receptor blockade assay. Additionally, transcription factor p65 and IRF1 in the HCC cells were revealed by CHIP assay to mediate the inducible PD-L1 expression. All the results demonstrate that M1 macrophages induced expression of PD-L1 in HCC cells, supporting the pro-tumor role of M1 macrophages.
肝细胞癌（HCC）是炎症相关癌症的典型代表，其肿瘤相关巨噬细胞中存在 M1 样和 M2 样巨噬细胞。M1 巨噬细胞被认为具有杀瘤作用，但一些研究报告称其具有促肿瘤作用。在 HCC 细胞中表达的程序性细胞死亡配体 1（PD-L1）是介导 HCC 免疫逃逸的关键检查点分子。HCC 细胞中 PD-L1 的表达是可诱导的。在本研究中，我们探讨了 M1 巨噬细胞是否诱导 HCC 细胞表达 PD-L1。首先，通过生物信息学和免疫组织化学实验确定了 M1 巨噬细胞浸润与 HCC 组织中 PD-L1 表达之间的相关性。在 GEO 数据库中 90 例 HCC 样本中，M1 巨噬细胞的富集评分与 HCC 细胞中 PD-L1 的表达相关。此外，CD68+HLA-DR+M1 样巨噬细胞的浸润与 HCC 细胞中 PD-L1 的表达水平相关。此外，从 THP-1 细胞、RAW264.7 细胞或小鼠骨髓中制备了 M1 条件培养基。这些上清液诱导了 HCC 细胞中 PD-L1 的表达。此外，通过 siRNA 测定和受体阻断测定，鉴定出上清液中的炎症细胞因子 IL-1β 是诱导 PD-L1 表达的原因。此外，通过 CHIP 测定发现 HCC 细胞中的转录因子 p65 和 IRF1 介导了可诱导的 PD-L1 表达。所有结果表明，M1 巨噬细胞诱导 HCC 细胞表达 PD-L1，支持 M1 巨噬细胞的促肿瘤作用。
