Kim Bong Kyun, Choi Hei Gwon, Lee Jae-Hyung, Choi In Wook, Yuk Jae-Min, Cha Guang-Ho, Lee Young-Ha
Department of Surgery, Daejeon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul 34943, Korea.
Brain Korea 21 FOUR Project for Medical Science, Chungnam National University, Daejeon 34956, Korea.
Parasites Hosts Dis. 2025 Feb;63(1):37-49. doi: 10.3347/PHD.24082. Epub 2025 Feb 25.
Cancer immunotherapy is widely used to treat various cancers to augment the weakened host immune response against tumors. Dendritic cells (DCs) are specialized antigen-presenting cells that play dual roles in inducing innate and adaptive immunity. Toxoplasma gondii is a protozoan parasite that exhibits anti-tumor activity against certain types of cancers. However, little is known about the anti-tumor effects of T. gondii or tumor/parasite antigen-pulsed DCs (DC vaccines, DCV) in breast cancer. In this study, C57BL/6 mice were administered E0771 mouse breast cancer cells (Cancer-injected) subcutaneously, T. gondii Me49 cysts orally (TG-injected), or DCs pulsed with breast cancer cell lysate antigen and T. gondii lysate antigens (DCV-injected) intraperitoneally. Tumor size and immunological characteristics were subsequently evaluated. We also evaluated matrix metalloproteinase (MMP)-2 and MMP-9 levels in E0771 mouse breast cancer cells co-cultured with T. gondii or DCs by RT-PCR. The tumor volumes of mice injected with breast cancer cells and antigen-pulsed DCs (Cancer/DCV-injected mice) were similar to those of Cancer-injected mice; however, they were significantly reduced in T. gondii-infected tumor-bearing (TG/Cancer-injected) mice. Moreover, tumor volumes were significantly reduced by adding antigen-pulsed DCs (TG/Cancer/DCV-injected mice) compared to TG/Cancer-injected mice. The levels of IFN-γ, serum IgG2a levels, and CD8+ T cell populations were significantly higher in DCV- and TG-injected mice than in control mice, while no significant differences between Cancer- and Cancer/DCV-injected mice were observed. The levels of IFN-γ, the IgG2a levels, and the percentage of CD8+ T cells were significantly increased in TG/Cancer- and TG/Cancer/DCV-injected mice than in Cancer-injected mice. IFN-γ levels and serum IgG2a levels were further increased in TG/Cancer/DCV-injected mice than in TG/Cancer-injected mice. The MMP-2 and MMP-9 mRNA expressions were significantly decreased in mouse breast cancer cells co-cultured with live T. gondii, T. gondii lysate antigen, or antigen-pulsed DCs (DCV) but not in inactivated DCs. These results indicate that T. gondii induces anti-tumor effects in breast cancer-bearing mice through the induction of strong Th1 immune responses, but not in antigen-pulsed DCs alone. The addition of antigen-pulsed DCs further augments the anti-tumor effects of T. gondii.
癌症免疫疗法被广泛用于治疗各种癌症，以增强宿主针对肿瘤的减弱的免疫反应。树突状细胞（DCs）是专门的抗原呈递细胞，在诱导先天免疫和适应性免疫中发挥双重作用。刚地弓形虫是一种原生动物寄生虫，对某些类型的癌症具有抗肿瘤活性。然而，关于刚地弓形虫或肿瘤/寄生虫抗原脉冲DCs（DC疫苗，DCV）在乳腺癌中的抗肿瘤作用知之甚少。在本研究中，给C57BL/6小鼠皮下注射E0771小鼠乳腺癌细胞（癌症注射组），口服刚地弓形虫Me49包囊（TG注射组），或腹腔注射用乳腺癌细胞裂解物抗原和刚地弓形虫裂解物抗原脉冲的DCs（DCV注射组）。随后评估肿瘤大小和免疫特征。我们还通过RT-PCR评估了与刚地弓形虫或DCs共培养的E0771小鼠乳腺癌细胞中基质金属蛋白酶（MMP）-2和MMP-9的水平。注射乳腺癌细胞和抗原脉冲DCs的小鼠（癌症/DCV注射组小鼠）的肿瘤体积与癌症注射组小鼠相似；然而，在感染刚地弓形虫的荷瘤（TG/癌症注射组）小鼠中肿瘤体积显著减小。此外，与TG/癌症注射组小鼠相比，添加抗原脉冲DCs（TG/癌症/DCV注射组小鼠）后肿瘤体积显著减小。DCV注射组和TG注射组小鼠中IFN-γ水平、血清IgG2a水平和CD8+T细胞群体显著高于对照小鼠，而癌症注射组和癌症/DCV注射组小鼠之间未观察到显著差异。TG/癌症注射组和TG/癌症/DCV注射组小鼠中IFN-γ水平、IgG2a水平和CD8+T细胞百分比显著高于癌症注射组小鼠。TG/癌症/DCV注射组小鼠中IFN-γ水平和血清IgG2a水平比TG/癌症注射组小鼠进一步升高。与活的刚地弓形虫、刚地弓形虫裂解物抗原或抗原脉冲DCs（DCV）共培养的小鼠乳腺癌细胞中MMP-2和MMP-9 mRNA表达显著降低，但在灭活的DCs中未降低。这些结果表明，刚地弓形虫通过诱导强烈的Th1免疫反应在荷乳腺癌小鼠中诱导抗肿瘤作用，但单独的抗原脉冲DCs则不能。添加抗原脉冲DCs进一步增强了刚地弓形虫的抗肿瘤作用。
