There has been no significant improvements for immune checkpoint inhibitors since its first use. Tumour-associated macrophages (TAMs) are critical mediators in the PD-1/PD-L1 axis, contributing to the immunosuppressive tumour microenvironment. This study aims to investigate the potential role of PD-L1 in regulating TAMs in glioblastoma. Gene expression data and clinical information of glioma patients were collected from TCGA (n = 614) and CGGA (n = 325) databases. Differentially expressed genes between PD-L1^high and PD-L1^low groups were identified and subjected to bioinformatical analysis. We found that PD-L1 was frequently expressed in gliomas with a grade-dependent pattern. Higher PD-L1 expression predicted shorter overall survival. Moreover, PD-L1 was positively correlated with immunosuppressive cells (macrophage, neutrophil and immature DC) and negatively correlated with cytocidal immune cells (CD8⁺ T cell and Th1). Importantly, PD-L1 high expression was significantly correlated with M2-polarization of macrophages (M2-TAMs). We conclude that PD-L1 is an unfavourable prognostic marker for patients with glioblastoma; PD-L1-mediated immunosuppression may attribute to the infiltration and M2-polarization of TAMs.

自从首次使用以来，免疫检查点抑制剂一直没有明显的改善。肿瘤相关的巨噬细胞（TAM）是PD-1 / PD-L1轴上的关键介质，有助于免疫抑制肿瘤微环境。这项研究旨在调查PD-L1在胶质母细胞瘤中调节TAM的潜在作用。从TCGA（n = 614）和CGGA（n = 325）数据库中收集神经胶质瘤患者的基因表达数据和临床信息。PD-L1^高和PD-L1^低之间的差异表达基因确定各组并进行生物信息学分析。我们发现PD-L1经常在神经胶质瘤中以等级依赖的模式表达。较高的PD-L1表达预测较短的总生存期。此外，PD-L1与免疫抑制细胞（巨噬细胞，嗜中性粒细胞和未成熟的DC）呈正相关，与杀细胞免疫细胞（CD8 ⁺ T细胞和Th1）呈负相关。重要的是，PD-L1高表达与巨噬细胞（M2-TAM）的M2极化显着相关。我们得出结论，PD-L1是胶质母细胞瘤患者不良的预后指标。PD-L1介导的免疫抑制可能归因于TAM的浸润和M2极化。