靶向 CCL2/CCR2 轴在癌症免疫治疗中的应用:一石三鸟?

Targeting the CCL2/CCR2 Axis in Cancer Immunotherapy: One Stone, Three Birds?

机构信息

Department of Drug Discovery, Shanghai Huaota Biopharm, Shanghai, China.

出版信息

Front Immunol. 2021 Nov 3;12:771210. doi: 10.3389/fimmu.2021.771210. eCollection 2021.

Abstract

CCR2 is predominantly expressed by monocytes/macrophages with strong proinflammatory functions, prompting the development of CCR2 antagonists to dampen unwanted immune responses in inflammatory and autoimmune diseases. Paradoxically, CCR2-expressing monocytes/macrophages, particularly in tumor microenvironments, can be strongly immunosuppressive. Thus, targeting the recruitment of immunosuppressive monocytes/macrophages to tumors by CCR2 antagonism has recently been investigated as a strategy to modify the tumor microenvironment and enhance anti-tumor immunity. We present here that beneficial effects of CCR2 antagonism in the tumor setting extend beyond blocking chemotaxis of suppressive myeloid cells. Signaling within the CCL2/CCR2 axis shows underappreciated effects on myeloid cell survival and function polarization. Apart from myeloid cells, T cells are also known to express CCR2. Nevertheless, tissue homing of Treg cells among T cell populations is preferentially affected by CCR2 deficiency. Further, CCR2 signaling also directly enhances Treg functional potency. Thus, although Tregs are not the sole type of T cells expressing CCR2, the net outcome of CCR2 antagonism in T cells favors the anti-tumor arm of immune responses. Finally, the CCL2/CCR2 axis directly contributes to survival/growth and invasion/metastasis of many types of tumors bearing CCR2. Together, CCR2 links to two main types of suppressive immune cells by multiple mechanisms. Such a CCR2-assoicated immunosuppressive network is further entangled with paracrine and autocrine CCR2 signaling of tumor cells. Strategies to target CCL2/CCR2 axis as cancer therapy in the view of three types of CCR2-expessing cells in tumor microenvironment are discussed.

摘要

CCR2 主要由具有强烈促炎功能的单核细胞/巨噬细胞表达,这促使人们开发 CCR2 拮抗剂来抑制炎症和自身免疫性疾病中不必要的免疫反应。矛盾的是,CCR2 表达的单核细胞/巨噬细胞,特别是在肿瘤微环境中,可以具有很强的免疫抑制作用。因此,最近人们研究了通过 CCR2 拮抗作用靶向招募抑制性单核细胞/巨噬细胞到肿瘤中,作为一种改变肿瘤微环境和增强抗肿瘤免疫的策略。我们在这里提出,CCR2 拮抗在肿瘤环境中的有益作用不仅限于阻断抑制性髓样细胞的趋化作用。CCL2/CCR2 轴内的信号转导对髓样细胞的存活和功能极化表现出被低估的影响。除了髓样细胞外,T 细胞也被认为表达 CCR2。然而,Treg 细胞在 T 细胞群体中的组织归巢优先受到 CCR2 缺陷的影响。此外,CCR2 信号还直接增强了 Treg 细胞的功能效力。因此,尽管 Treg 细胞不是唯一表达 CCR2 的 T 细胞类型,但 CCR2 拮抗在 T 细胞中的净结果有利于免疫反应的抗肿瘤作用。最后,CCL2/CCR2 轴直接促进了许多携带 CCR2 的肿瘤类型的存活/生长、侵袭/转移。总之,CCR2 通过多种机制与两种主要类型的抑制性免疫细胞相关联。这种 CCR2 相关的免疫抑制网络与肿瘤细胞的旁分泌和自分泌 CCR2 信号进一步交织在一起。从肿瘤微环境中三种 CCR2 表达细胞的角度讨论了将 CCL2/CCR2 轴作为癌症治疗的策略。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/0d73/8596464/e60e4a77aa74/fimmu-12-771210-g001.jpg

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