Abstract：
OBJECTIVE: Elevated myeloid-derived suppressor cells (MDSCs) in many malignancies are associated with the increased risk for metastases and poor prognosis. Therefore, a mouse model of intraocular melanoma was established to explore how MDSCs influence liver metastases.
METHODS: In this study, murine B16LS melanoma cells were transplanted into the posterior compartment (PC) of the eye of C57BL/6 mice. Leucocytes from the liver of naive mice and mice bearing melanoma liver metastasis were isolated using isotonic Percoll centrifugation, examined by flow cytometry for their expression of Gr1, CD11b, F4/80, RAE-1, and Mult-1, and further isolated for MDSCs and natural killer (NK) cells. The effects of MDSCs on NK cells were tested by coculturing and assessing the ability of NK cells to produce interferon-gamma (IFN-γ) by ELISA and NK cell cytotoxicity by 3H-thymidine incorporation assay. The impact of IFN-γ on liver metastases was examined via selectively depleting IFN-γ in vivo.
RESULTS: The results showed that mice with liver metastases had increased levels of CD11b+Gr1+F4/80+ as well as CD11b+Gr1+F4/80- MDSCs. MDSCs significantly enhanced the generation of IFN-γ together with the cytotoxicity of the NK cells. Furthermore, these effects were cell-cell contact-dependent. Although IFN-γ was not of a toxic nature to the melanoma cells, it profoundly inhibited B16LS cell proliferation. Depleting IFN-γ in vivo led to increased liver metastases.
CONCLUSIONS: All these findings first revealed that MDSCs accumulated in liver metastasis of intraocular melanoma could activate the NK cells to produce an effective anti-tumor immune response. Thus, the MDSCs\' performance in different tumor models would need more investigation to boost current immunotherapy modalities.
METHODS: In this study, murine B16LS melanoma cells were transplanted into the posterior compartment (PC) of the eye of C57BL/6 mice. Leucocytes from the liver of naive mice and mice bearing melanoma liver metastasis were isolated using isotonic Percoll centrifugation, examined by flow cytometry for their expression of Gr1, CD11b, F4/80, RAE-1, and Mult-1, and further isolated for MDSCs and natural killer (NK) cells. The effects of MDSCs on NK cells were tested by coculturing and assessing the ability of NK cells to produce interferon-gamma (IFN-γ) by ELISA and NK cell cytotoxicity by 3H-thymidine incorporation assay. The impact of IFN-γ on liver metastases was examined via selectively depleting IFN-γ in vivo.
RESULTS: The results showed that mice with liver metastases had increased levels of CD11b+Gr1+F4/80+ as well as CD11b+Gr1+F4/80- MDSCs. MDSCs significantly enhanced the generation of IFN-γ together with the cytotoxicity of the NK cells. Furthermore, these effects were cell-cell contact-dependent. Although IFN-γ was not of a toxic nature to the melanoma cells, it profoundly inhibited B16LS cell proliferation. Depleting IFN-γ in vivo led to increased liver metastases.
CONCLUSIONS: All these findings first revealed that MDSCs accumulated in liver metastasis of intraocular melanoma could activate the NK cells to produce an effective anti-tumor immune response. Thus, the MDSCs\' performance in different tumor models would need more investigation to boost current immunotherapy modalities.
摘要：
目的：许多恶性肿瘤中髓源性抑制细胞（MDSC）的升高与转移风险增加和预后不良相关。因此,建立了小鼠眼内黑色素瘤模型,以探讨MDSCs如何影响肝转移.
方法：在本研究中，将鼠B16LS黑素瘤细胞移植到C57BL/6小鼠眼睛的后室(PC)中。使用等渗Percoll离心从幼稚小鼠和患有黑色素瘤肝转移的小鼠的肝脏中分离白细胞，通过流式细胞术检查它们的Gr1，CD11b，F4/80，RAE-1和Mult-1，并进一步分离用于MDSC和自然杀伤（NK）细胞。通过共培养并通过ELISA评估NK细胞产生干扰素-γ（IFN-γ）的能力和通过3H-胸苷掺入测定法评估NK细胞的细胞毒性来测试MDSC对NK细胞的影响。通过在体内选择性消耗IFN-γ来检查IFN-γ对肝转移的影响。
结果：结果显示，肝转移小鼠CD11b+Gr1+F4/80+以及CD11b+Gr1+F4/80-MDSCs水平升高。MDSC显著增强IFN-γ的产生以及NK细胞的细胞毒性。此外，这些效应是细胞-细胞接触依赖性的.虽然IFN-γ对黑色素瘤细胞没有毒性，它极大地抑制了B16LS细胞的增殖。体内消耗IFN-γ导致肝转移增加。
结论：所有这些发现首先表明，在眼内黑色素瘤肝转移中积累的MDSCs可以激活NK细胞，产生有效的抗肿瘤免疫应答。因此，MDSCs在不同肿瘤模型中的表现需要更多的研究以促进目前的免疫治疗方式.
方法：在本研究中，将鼠B16LS黑素瘤细胞移植到C57BL/6小鼠眼睛的后室(PC)中。使用等渗Percoll离心从幼稚小鼠和患有黑色素瘤肝转移的小鼠的肝脏中分离白细胞，通过流式细胞术检查它们的Gr1，CD11b，F4/80，RAE-1和Mult-1，并进一步分离用于MDSC和自然杀伤（NK）细胞。通过共培养并通过ELISA评估NK细胞产生干扰素-γ（IFN-γ）的能力和通过3H-胸苷掺入测定法评估NK细胞的细胞毒性来测试MDSC对NK细胞的影响。通过在体内选择性消耗IFN-γ来检查IFN-γ对肝转移的影响。
结果：结果显示，肝转移小鼠CD11b+Gr1+F4/80+以及CD11b+Gr1+F4/80-MDSCs水平升高。MDSC显著增强IFN-γ的产生以及NK细胞的细胞毒性。此外，这些效应是细胞-细胞接触依赖性的.虽然IFN-γ对黑色素瘤细胞没有毒性，它极大地抑制了B16LS细胞的增殖。体内消耗IFN-γ导致肝转移增加。
结论：所有这些发现首先表明，在眼内黑色素瘤肝转移中积累的MDSCs可以激活NK细胞，产生有效的抗肿瘤免疫应答。因此，MDSCs在不同肿瘤模型中的表现需要更多的研究以促进目前的免疫治疗方式.
