ADAR1 是 RNA 编辑的主要酶，通过调节干扰素介导的先天免疫，已成为癌症免疫治疗效果的肿瘤内在关键决定因素。然而，ADAR1 在巨噬细胞等先天免疫细胞中的作用仍然未知。我们首先分析了公开的患者来源的单细胞 RNA 测序和扰动 RNA 测序数据，以阐明 ADAR1 在巨噬细胞中的表达和功能。随后，我们在三种不同疾病小鼠模型中评估了巨噬细胞中 ADAR1 条件性敲除和干扰素 (IFN)-γ 治疗对肿瘤生长的综合影响：LLC（肺癌）、B16-F10（黑色素瘤）和 MC38（结肠癌）。为了获得机制见解，我们进行了人类细胞因子阵列，以识别 THP-1 细胞中 ADAR1 扰动时差异分泌的细胞因子。此外，我们通过小鼠肿瘤切片的免疫组织化学染色和使用 HUVEC 和 SVEC4-10 细胞的管形成实验检查了 ADAR1 缺失和 IFN-γ 治疗对血管形成的影响。我们还使用免疫荧光和免疫组织化学染色以及流式细胞术评估了对 CD8 T 细胞的影响。为了探索转化潜力，我们检查了在 LLC 荷瘤小鼠中注射 ADAR1 缺陷型巨噬细胞和 IFN-γ 治疗对肿瘤生长的影响。我们对公共数据的分析表明，巨噬细胞中 ADAR1 的缺失可促进抗肿瘤免疫，就像癌细胞中的抗肿瘤免疫一样。事实上，巨噬细胞中的 ADAR1 缺失与 IFN-γ 治疗相结合可导致多种疾病小鼠模型中的肿瘤消退。从机制上讲，巨噬细胞中 ADAR1 的缺失导致关键细胞因子的分泌差异：它通过激活 PKR/EIF2α 信号传导抑制 CCL20、GDF15、IL-18BP 和 TIM-3 的翻译，但通过转录增加 IFN-γ 的分泌。由于 5'UTR uORF，上调和白细胞介素 (IL)-18。因此，CCL20和GDF15的减少以及IFN-γ的增加抑制血管生成，而IL-18BP和TIM-3的减少以及IL-18的增加通过增强CD8 T细胞的细胞毒性来诱导抗肿瘤免疫。我们进一步证明，注射 ADAR1 缺陷型巨噬细胞和 IFN-γ 的联合疗法可有效抑制体内肿瘤。这项研究全面阐明了巨噬细胞内 ADAR1 的缺失如何有助于建立抗肿瘤微环境，表明了靶向 ADAR1 的治疗潜力超出癌细胞范围。© 作者（或其雇主）2023。根据 CC BY-NC 允许重复使用。不得商业再利用。请参阅权利和权限。由英国医学杂志出版。

ADAR1, the major enzyme for RNA editing, has emerged as a tumor-intrinsic key determinant for cancer immunotherapy efficacy through modulating interferon-mediated innate immunity. However, the role of ADAR1 in innate immune cells such as macrophages remains unknown.We first analyzed publicly accessible patient-derived single-cell RNA-sequencing and perturbed RNA sequencing data to elucidate the ADAR1 expression and function in macrophages. Subsequently, we evaluated the combined effects of ADAR1 conditional knockout in macrophages and interferon (IFN)-γ treatment on tumor growth in three distinct disease mouse models: LLC for lung cancer, B16-F10 for melanoma, and MC38 for colon cancer. To gain the mechanistic insights, we performed human cytokine arrays to identify differentially secreted cytokines in response to ADAR1 perturbations in THP-1 cells. Furthermore, we examined the effects of ADAR1 loss and IFN-γ treatment on vessel formation through immunohistochemical staining of mouse tumor sections and tube-forming experiments using HUVEC and SVEC4-10 cells. We also assessed the effects on CD8+ T cells using immunofluorescent and immunohistochemical staining and flow cytometry. To explore the translational potential, we examined the consequences of injecting ADAR1-deficient macrophages alongside IFN-γ treatment on tumor growth in LLC-tumor-bearing mice.Our analysis on public data suggests that ADAR1 loss in macrophages promotes antitumor immunity as in cancer cells. Indeed, ADAR1 loss in macrophages combined with IFN-γ treatment results in tumor regression in diverse disease mouse models. Mechanistically, the loss of ADAR1 in macrophages leads to the differential secretion of key cytokines: it inhibits the translation of CCL20, GDF15, IL-18BP, and TIM-3 by activating PKR/EIF2α signaling but increases the secretion of IFN-γ through transcriptional upregulation and interleukin (IL)-18 due to the 5'UTR uORF. Consequently, decreased CCL20 and GDF15 and increased IFN-γ suppress angiogenesis, while decreased IL-18BP and TIM-3 and increased IL-18 induce antitumor immunity by enhancing cytotoxicity of CD8+ T cells. We further demonstrate that combination therapy of injecting ADAR1-deficient macrophages and IFN-γ effectively suppresses tumors in vivo.This study provides a comprehensive elucidation of how ADAR1 loss within macrophages contributes to the establishment of an antitumor microenvironment, suggesting the therapeutic potential of targeting ADAR1 beyond the scope of cancer cells.© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.