TREM2 ablation boosts GPC3-CAR-T therapy by reprogramming TAMs and enhancing adaptive immunity in HCC

Despite the promise of chimeric antigen receptor (CAR)-T therapy in hepatocellular carcinoma (HCC), its efficacy is severely limited by the immunosuppressive tumor microenvironment (TME), and the underlying mechanism remains unclear. Using immunocompetent orthotopic HCC models with hGPC3-targeted CAR-T therapy, we identified Trem2+ tumor-associated macrophages (TAMs) as pivotal suppressors of CAR-T efficacy. ScRNA-seq revealed that genetic Trem2 ablation synergized with CART-T to remodel the TME by reprogramming TAMs toward an anti-tumor CXCL9-high/SPP-low phenotype. This shift occured through enhanced oxidative phosphorylation and suppressed glycolytic flux. Mechanistically, Trem2 knockout (Trem2-KO) blocked SYK-PI3K-AKT-mTOR glycolytic signaling, while CAR-T derived IFN-gamma activated JAK1-STAT1 and AMPK-driven metabolism. Crucially, Trem2-KO up-regulated CD40 on TAMs, enabling CD40 agnoism to directly recapitulate Trem2-KO effects via AMPK-mediated mTOR suppression and STAT1-driven CXCL9 production. Eventually, it producd TAMs metabolic reprogram and recruited adaptive tumor infiltrating CD8+ T cells. This novel strategy redefined HCC CAR-T therapy by reeducating TAMs as a universal amplifier that converts TME, and circumvented TREM2-blockade associated neurotoxicity risks. This paradigm shift targeted TAMs metabolism rather than CAR-T engineering, provides a clinically actionable insight for solid tumors.

尽管嵌合抗原受体（chimeric antigen receptor, CAR）-T细胞疗法在肝细胞癌（hepatocellular carcinoma, HCC）中展现出应用前景，但其疗效却因免疫抑制性肿瘤微环境（tumor microenvironment, TME）受到严重限制，且其潜在作用机制仍未明确。本研究采用靶向人GPC3的CAR-T细胞疗法联合免疫健全原位肝癌模型，鉴定出表达Trem2的肿瘤相关巨噬细胞（Trem2+ tumor-associated macrophages, TAMs）是CAR-T疗效的关键抑制因子。单细胞RNA测序（scRNA-seq）结果显示，遗传敲除Trem2可与CAR-T协同重塑肿瘤微环境，将TAMs重编程为抗肿瘤表型的CXCL9高表达/SPP低表达细胞群。该表型转变通过增强氧化磷酸化、抑制糖酵解通量得以实现。机制层面，Trem2敲除（Trem2-KO）可阻断SYK-PI3K-AKT-mTOR糖酵解信号通路，而CAR-T细胞分泌的干扰素γ（IFN-γ）则能够激活JAK1-STAT1通路及腺苷酸活化蛋白激酶（AMPK）介导的代谢过程。尤为关键的是，Trem2-KO可上调TAMs表面的CD40分子，使得CD40激动剂能够通过AMPK介导的mTOR抑制及STAT1驱动的CXCL9产生，直接复刻Trem2-KO的效应。最终，该过程实现了TAMs的代谢重编程，并招募了适应性肿瘤浸润CD8+ T细胞。这一全新策略通过将TAMs重编程为重塑肿瘤微环境的通用放大器，重新定义了肝细胞癌的CAR-T细胞疗法，同时规避了TREM2阻断相关的神经毒性风险。这种靶向TAMs代谢而非CAR-T工程化的研究范式转变，为实体瘤的临床转化提供了具有可行性的新思路。