CCL2-CCR2 轴通过 PD-1 信号招募肿瘤相关巨噬细胞诱导免疫逃逸在食管癌变中。

BACKGROUND: The poor prognosis of esophageal squamous cell carcinoma (ESCC) highlights the need for novel strategies against this disease. Our previous study suggested the involvement of CCL2 and tumor associated macrophages (TAMs) in esophageal carcinogenesis. Despite the recognition of TAMs as a promising target for cancer treatment, mechanisms underlying its infiltration, activation and tumor-promotive function in ESCC remain unknown. METHODS: Human esophageal tissue array and TCGA database were used to evaluate the clinical relevance of CCL2 and TAMs in ESCC. F344 rats and C57BL/6 mice were treated with N-nitrosomethylbenzylamine (NMBA) to establish orthotopic models of esophageal carcinogenesis. CCL2/CCR2 gene knockout mice and macrophage-specific PPARG gene knockout mice were respectively used to investigate the role of infiltration and polarization of TAMs in ESCC. CCL2-mediated monocyte chemotaxis was estimated in malignantly transformed Het-1A cells. THP-1 cells were used to simulate TAMs polarization in vitro. RNA-sequencing was performed to uncover the mechanism. RESULTS: Increasing expression of CCL2 correlated with TAMs accumulation in esophageal carcinogenesis, and they both predicts poor prognosis in ESCC cohort. Animal studies show blockade of CCL2-CCR2 axis strongly reduces tumor incidence by hindering TAMs recruitment and thereby potentiates the antitumor efficacy of CD8 T cells in the tumor microenvironment. More importantly, M2 polarization increases PD-L2 expression in TAMs, resulting in immune evasion and tumor promotion through PD-1 signaling pathway. CONCLUSION: This study highlights the role of CCL2-CCR2 axis in esophageal carcinogenesis. Our findings provide new insight into the mechanism of immune evasion mediated by TAMs in ESCC, suggesting the potential of TAMs-targeted strategies for ESCC prevention and immunotherapy.

背景：食管鳞状细胞癌（ESCC）预后不良，这凸显了开发针对该疾病的新策略的必要性。我们之前的研究表明 CCL2 和肿瘤相关巨噬细胞（TAMs）参与了食管癌变。尽管 TAMs 作为癌症治疗的一个有前途的靶点已经得到认可，但 TAMs 浸润、激活及其在 ESCC 中的促肿瘤功能的机制仍不清楚。

方法：使用人食管组织阵列和 TCGA 数据库评估 CCL2 和 TAMs 在 ESCC 中的临床相关性。使用 N-亚硝基甲基苄胺（NMBA）处理 F344 大鼠和 C57BL/6 小鼠，建立食管致癌的原位模型。分别使用 CCL2/CCR2 基因敲除小鼠和巨噬细胞特异性过氧化物酶体增殖物激活受体 γ（PPARG）基因敲除小鼠，研究 TAMs 浸润和极化在 ESCC 中的作用。用恶性转化的 Het-1A 细胞评估 CCL2 介导的单核细胞趋化作用。用 THP-1 细胞模拟体外 TAMs 极化。进行 RNA 测序以揭示机制。

结果：CCL2 表达增加与食管癌变过程中 TAMs 的积累相关，并且在 ESCC 队列中均预示预后不良。动物研究表明，阻断 CCL2-CCR2 轴通过抑制 TAMs 的募集强烈降低肿瘤发生率，从而增强肿瘤微环境中 CD8 T 细胞的抗肿瘤功效。更重要的是，M2 极化增加了 TAMs 中的 PD-L2 表达，通过 PD-1 信号通路导致免疫逃逸和肿瘤促进。

结论：本研究强调了 CCL2-CCR2 轴在食管癌变中的作用。我们的研究结果为 TAMs 在 ESCC 中介导的免疫逃逸机制提供了新的见解，提示了针对 TAMs 的策略在 ESCC 预防和免疫治疗中的潜力。