CD169 is a marker of IFN-γ-stimulated inflammatory macrophages in brain tumor [WG vs TG]

Therapies against glioblastoma multiforme (GBM) have been largely ineffective due to the infiltration of immunosuppressive tumor-associated macrophages (TAMs). Recent studies demonstrated that TAMs can also be immune-activating. However, markers differentiating these heterogeneous macrophage populations have not been established. In this study, we identified a subset of macrophages expressing CD169 that promote an anti-tumoral microenvironment in GBM. Using single-cell transcriptome analysis, we found that CD169+ macrophages in human and mouse gliomas produced proinflammatory chemokines, leading to the accumulation of T cells and NK cells. Depletion of CD169+ macrophages shortened the survival of mice with gliomas and reduced the function of antitumor lymphocytes. We show that IFN-γ produced by NK cells was critical for the accumulation of CD169+ macrophages into gliomas. Additionally, CD169 expression on macrophages increased the phagocytosis of apoptotic glioma cells. Our finding suggests that the CD169+ subset of TAMs promotes antitumor immune responses against GBM. We analyzed glioma infiltrated immune cells by single cell RNA sequencing (scRNAseq) with 10X genomics. C57BL/6 background CD169-DTR wild type or hetero type mice were treated with diphtheria toxin and intracranially injected with GL261 mouse glioma cell line. Cells in tumor were isolated at 10 days after inoculation and sorted CD45-positive immune cells were analyzed.

多形性胶质母细胞瘤（glioblastoma multiforme, GBM）的临床治疗方案大多收效甚微，核心诱因在于免疫抑制性肿瘤相关巨噬细胞（tumor-associated macrophages, TAMs）的肿瘤浸润。近期研究证实，TAMs亦可具备免疫激活功能，但目前仍未确立可区分这些异质性巨噬细胞群体的特异性标志物。本研究中，我们成功鉴定出一类表达CD169的巨噬细胞亚群，该亚群可在胶质母细胞瘤微环境中发挥抗肿瘤作用。借助单细胞转录组测序分析，我们发现人与小鼠胶质瘤组织内的CD169+巨噬细胞可分泌促炎性趋化因子，进而介导T细胞与自然杀伤细胞（natural killer cells, NK cells）的募集。实验结果显示，耗竭CD169+巨噬细胞会缩短胶质瘤模型小鼠的存活时长，并削弱抗肿瘤淋巴细胞的功能。我们进一步证实，自然杀伤细胞分泌的干扰素-γ（IFN-γ）是CD169+巨噬细胞向胶质瘤组织募集的关键调控因子。此外，巨噬细胞表面的CD169表达可增强其对凋亡胶质瘤细胞的吞噬能力。本研究结果表明，TAMs中的CD169+亚群可介导针对胶质母细胞瘤的抗肿瘤免疫应答。我们采用10X Genomics平台的单细胞RNA测序（single cell RNA sequencing, scRNAseq）分析了胶质瘤浸润免疫细胞：将携带C57BL/6背景的CD169-DTR野生型或杂合型小鼠施以白喉毒素处理，并颅内接种GL261小鼠胶质瘤细胞系；于接种后10天分离肿瘤组织内的细胞，对分选获得的CD45阳性免疫细胞开展测序分析。