Single cell expression profiling of whole B16F10 melanoma tumors, treated with PBS or DCP-IL-12/FLT3L.. Single cell expression profiling of whole B16F10 melanoma tumors, treated with PBS or DCP-IL-12/FLT3L.

Dendritic cells (DCs) are specialized myeloid cells with the ability to uptake, process, and present antigens to T lymphocytes. They also generate cytokine and chemokine gradients that regulate immune cell trafficking, activation, and function. Monocyte-derived DCs (moDCs) pulsed with tumor antigens have been used as a platform for therapeutic vaccination in cancer. However, in spite of significant development and testing, antigen-loaded moDCs have delivered mixed clinical results. Here we present a DC therapy that uses a population of mouse or human DC progenitors (DCPs) engineered to produce two immunostimulatory cytokines, IL-12 and FLT3L. In the absence of antigen loading, cytokine-armored DCPs efficiently differentiated into conventional type I DCs (cDC1) and inhibited tumor growth in melanoma and autochthonous liver cancer models. Tumor response to DCP therapy involved synergy between IL-12 and FLT3L and was associated with early NK cell activation and massive effector T cell infiltration, robust M1-like macrophage programming, and ischemic tumor necrosis. Mechanistically, anti-tumor immunity was dependent on endogenous cDC1 expansion and interferon-γ (IFNγ) production and signaling, but did not require CD8+ T cell cytotoxicity. In one application, cytokine-armored DCPs synergized with antigen-specific CAR-T cells to eradicate intracranial gliomas in mice. Overall design: Single cell expression profiling of whole B16F10 melanoma tumors, treated with PBS or DCP-IL-12/FLT3L, in triplicates.

树突状细胞（dendritic cells, DCs）是一类特化的髓系细胞，具备摄取、加工抗原并将其呈递给T淋巴细胞的能力。它们还可产生细胞因子与趋化因子梯度，以此调控免疫细胞的迁移、活化与功能。单核细胞衍生树突状细胞（monocyte-derived DCs, moDCs）经肿瘤抗原负载后，已被用作癌症治疗性疫苗的开发平台。不过，尽管相关研究与测试已取得长足进展，负载抗原的moDCs在临床应用中却呈现出参差不齐的效果。本研究报道一款树突状细胞疗法，该疗法使用经工程改造以表达两种免疫刺激性细胞因子IL-12与FLT3L的小鼠或人源树突状细胞祖细胞（DC progenitors, DCPs）群体。在无需抗原负载的前提下，经细胞因子修饰的DCPs可高效分化为经典I型树突状细胞（conventional type I DCs, cDC1），并在黑色素瘤与自发性肝癌模型中抑制肿瘤生长。DCP疗法的抗肿瘤响应依赖于IL-12与FLT3L的协同作用，且与早期NK细胞活化、大量效应T细胞浸润、显著的M1样巨噬细胞重编程以及缺血性肿瘤坏死密切相关。从机制层面来看，抗肿瘤免疫依赖于内源性cDC1的扩增以及干扰素-γ（interferon-γ, IFNγ）的产生与信号传导，但并不需要CD8+ T细胞的细胞毒性活性。在一项应用场景中，经细胞因子修饰的DCPs可与抗原特异性CAR-T细胞协同作用，根除小鼠颅内胶质瘤。整体实验设计：对经PBS或DCP-IL-12/FLT3L处理的完整B16F10黑色素瘤组织进行单细胞表达谱分析，每组设置三次生物学重复。