Department of Pathogen Biology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, Guangdong, 510515, People's Republic of China.
Parasit Vectors. 2021 Dec 11;14(1):601. doi: 10.1186/s13071-021-05032-6.
Breast cancer is the most common cause of cancer-related death among women, and prognosis is especially poor for patients with triple-negative breast cancer (TNBC); therefore, there is an urgent need for new effective therapies. Recent studies have demonstrated that the uracil auxotroph Toxoplasma gondii vaccine displays anti-tumor effects. Here, we examined the immunotherapy effects of an attenuated uracil auxotroph strain of T. gondii against 4T1 murine breast cancer.
We constructed a uracil auxotroph T. gondii RH strain via orotidine 5'-monophosphate decarboxylase gene deletion (RH-Δompdc) with CRISPR/Cas9 technology. The strain's virulence in the T. gondii-infected mice was determined in vitro and in vivo by parasite replication assay, plaque assay, parasite burden detection in mice peritoneal fluids and survival analysis. The immunomodulation ability of the strain was evaluated by cytokine detection. Its anti-tumor effect was evaluated after its in situ inoculation into 4T1 tumors in a mouse model; the tumor volume was measured, and the 4T1 lung metastasis was detected by hematoxylin and eosin and Ki67 antibody staining, and the cytokine levels were measured by an enzyme-linked immunosorbent assay.
The RH-Δompdc strain proliferated normally when supplemented with uracil, but it was unable to propagate without the addition of uracil and in vivo, which suggested that it was avirulent to the hosts. This mutant showed vaccine characteristics that could induce intense immune responses both in vitro and in vivo by significantly boosting the expression of inflammatory cytokines. Inoculation of RH-Δompdc in situ into the 4T1 tumor inhibited tumor growth, reduced lung metastasis, promoted the survival of the tumor-bearing mice and increased the secretion of Th1 cytokines, including interleukin-12 (IL-12) and interferon-γ (INF-δ), in both the serum and tumor microenvironment (TME).
Inoculation of the uracil auxotroph RH-Δompdc directly into the 4T1 tumor stimulated anti-infection and anti-tumor immunity in mice, and resulted in inhibition of tumor growth and metastasis, promotion of the survival of the tumor-bearing mice and increased secretion of IL-12 and IFN-γ in both the serum and TME. Our findings suggest that the immunomodulation caused by RH-Δompdc could be a potential anti-tumor strategy.
乳腺癌是女性癌症相关死亡的最常见原因，三阴性乳腺癌（TNBC）患者的预后尤其差；因此，迫切需要新的有效治疗方法。最近的研究表明，尿嘧啶营养缺陷型弓形虫疫苗具有抗肿瘤作用。在这里，我们研究了减毒尿嘧啶营养缺陷型弓形虫 RH 株对 4T1 鼠乳腺癌的免疫治疗作用。
我们通过 CRISPR/Cas9 技术构建了一种通过鸟苷酸 5'-单磷酸脱羧酶基因缺失（RH-Δompdc）构建的尿嘧啶营养缺陷型弓形虫 RH 株。通过寄生虫复制试验、噬菌斑试验、小鼠腹腔液寄生虫载量检测和生存分析，在弓形虫感染小鼠体内和体外检测该菌株的毒力。通过细胞因子检测评估该菌株的免疫调节能力。将其原位接种到小鼠模型中的 4T1 肿瘤后，评估其抗肿瘤作用；测量肿瘤体积，并通过苏木精和伊红及 Ki67 抗体染色检测 4T1 肺转移，通过酶联免疫吸附试验检测细胞因子水平。
RH-Δompdc 株在补充尿嘧啶时可正常增殖，但在无尿嘧啶添加和体内情况下无法繁殖，表明其对宿主无毒性。该突变株具有疫苗特征，可通过显著增强炎症细胞因子的表达，在体外和体内诱导强烈的免疫反应。将 RH-Δompdc 原位接种到 4T1 肿瘤中可抑制肿瘤生长，减少肺转移，促进荷瘤小鼠的生存，并增加血清和肿瘤微环境（TME）中 Th1 细胞因子（包括白细胞介素-12（IL-12）和干扰素-γ（INF-γ））的分泌。
将尿嘧啶营养缺陷型 RH-Δompdc 直接接种到 4T1 肿瘤中可刺激小鼠抗感染和抗肿瘤免疫，抑制肿瘤生长和转移，促进荷瘤小鼠的生存，并增加血清和 TME 中 IL-12 和 IFN-γ 的分泌。我们的研究结果表明，RH-Δompdc 引起的免疫调节可能是一种潜在的抗肿瘤策略。
