Abstract：
Determining the appropriate source of antigens for optimal antigen presentation to T cells is a major challenge in designing dendritic cell (DC) -based therapeutic strategies against hepatocellular carcinoma (HCC). Tumor-derived exosomes (Tex) express a wide range of tumor antigens, making them a promising source of antigens for DC vaccines. As reported, the exosomes secreted by tumor cells can inhibit the antitumor function of immune cells. In this study, we transfected hepatocellular carcinoma cells with Rab27a to enhance the yield of exosomes, which were characterized using transmission electron microscopy and Western blot analysis. We found that Tex secreted by overexpressing Rab27a Hepatocellular carcinoma cell lines pulsed DC is beneficial for the differentiation and maturation of DCs but inhibits the secretion of the IL-12 cytokine. Consequently, we developed a complementary immunotherapy approach by using Tex as an antigen loaded onto DCs, in combination with the cytokine IL-12 to induce antigen-specific cytotoxic T lymphocytes （CTLs）. The results indicated that the combination of DC-Tex and IL-12 was more effective in stimulating T lymphocyte proliferation, releasing IFN-γ， and enhancing cytotoxicity compared to using exosomes or IL-12 alone. Additionally, the inclusion of IL-12 also compensated for the reduced IL-2 secretion by DCs caused by Tex. Moreover, in a BALB/c nude mice model of hepatocellular carcinoma, CTLs induced by DC-Tex combined with IL-12 maximized the tumor-specific T-cell immune effect and suppressed tumor growth. Thus, Tex provides a novel and promising source of antigens, with cytokines compensating for the shortcomings of Tex as a tumor antigen. This work helps to clarify the role of exosomes in tumor immunotherapy and may offer a safe and effective prospective strategy for the clinical application of exosome-based cellular immunotherapy.
摘要：
在设计基于树突状细胞(DC)的针对肝细胞癌(HCC)的治疗策略中,确定用于T细胞的最佳抗原呈递的抗原的适当来源是主要挑战。肿瘤来源的外泌体（Tex）表达广泛的肿瘤抗原，使它们成为DC疫苗的有希望的抗原来源。据报道，肿瘤细胞分泌的外泌体可以抑制免疫细胞的抗肿瘤功能。在这项研究中,我们用Rab27a转染肝癌细胞以提高外泌体的产量，使用透射电子显微镜和蛋白质印迹分析进行表征。我们发现，通过过表达Rab27a脉冲DC的肝细胞癌细胞系分泌的Tex有利于DC的分化和成熟，但抑制IL-12细胞因子的分泌。因此,我们通过使用Tex作为负载到DC上的抗原开发了一种互补的免疫治疗方法，与细胞因子IL-12联合诱导抗原特异性细胞毒性T淋巴细胞（CTL）。结果表明，DC-Tex和IL-12的组合更有效地刺激T淋巴细胞增殖，与单独使用外泌体或IL-12相比，释放IFN-γ并增强细胞毒性。此外,IL-12的包含也补偿了由Tex引起的DC减少的IL-2分泌。此外，在BALB/c裸鼠肝细胞癌模型中，由DC-Tex与IL-12联合诱导的CTL最大化了肿瘤特异性T细胞免疫效应并抑制了肿瘤生长。因此，Tex提供了一种新颖且有前途的抗原来源，用细胞因子补偿Tex作为肿瘤抗原的缺点。这项工作有助于阐明外泌体在肿瘤免疫治疗中的作用，并可能为基于外泌体的细胞免疫治疗的临床应用提供安全有效的前瞻性策略。
