T细胞分泌的γ干扰素促进了环磷酰胺（CTX）化疗引起的髓系抑制性细胞（MDSCs）比例升高

发布时间：2018-02-05 00:51

本文关键词： 环磷酰胺 MDSCs IFN-γ 4T1乳腺癌　出处：《浙江大学》2011年硕士论文　论文类型：学位论文

【摘要】：髓系来源的抑制性细胞MDSCs (Myeloid-derived suppressor cells, MDSCs)是一类具有负向免疫调控功能的异质性细胞群体,由处于早期分化阶段的髓系细胞组成,在小鼠中MDSCs的表型为Gr-1+CD11b+。在肿瘤、慢性感染、创伤和应激等多种病理状态下,此群细胞在骨髓、脾脏、淋巴结、外周血以及疾病发生部位聚积。在动物肿瘤模型和肿瘤患者体内,MDSCs在以上部位的大量聚积主要是由于肿瘤细胞在生长增殖过程中分泌的众多细胞因子如粒单核细胞集落刺激因子(GM-CSF)、血管内皮生长因子(VEGF)、白细胞介素(IL-6)等诱导。研究表明,MDSCs可通过分泌精氨酸酶(Arginase 1)、诱导性一氧化氮合酶2 (iNOS2)以及分泌抑制性细胞因子如转化生长因子β(TGF-p)等多种途径抑制T淋巴细胞正常功能的发挥从而展示强大的免疫抑制作用,尤其是抑制CD8+T细胞的功能,这种免疫抑制作用导致肿瘤细胞能够逃避机体免疫系统的识别及杀伤。同时,浸润于肿瘤组织部位的MDSCs还能够通过释放金属基质蛋白酶-9(MMP-9)和金属基质蛋白酶-13(MMP-13)促进肿瘤血管的生成以及肿瘤的生长、浸润和转移,从而更加有利于肿瘤的发生发展。环磷酰胺(CTX)作为一种烷基化药物能够直接杀伤肿瘤细胞,已被广泛地应用于肿瘤的化疗。可是,研究发现,经过环磷酰胺化疗的肿瘤患者中,骨髓,脾脏和外周血的MDSCs细胞的比例与未接受化疗的肿瘤患者相比反而更高,此种情况也见于环磷酰胺化疗的肿瘤小鼠模型中。这种环磷酰胺化疗引起MDSCs比例增高效应显然不利于环磷酰胺的抗肿瘤作用。免疫细胞之间可通过相互作用来调节宿主整体的免疫应答,我们推测CTX化疗后MDSCs比例的升高可能是T细胞促进的。为了解CTX化疗后引起MDSCs比例升高的原因和机制,我们通过实验对比了环磷酰胺化疗的肿瘤小鼠(4T1转移性小鼠乳腺癌模型)和未经化疗的肿瘤小鼠的免疫微环境的差异,发现在环磷酰胺化疗后早期MDSCs比例尚未明显上升之前,CD4+T细胞和CD8+T细胞经历了明显的扩增并产生大量γ-干扰素(IFN-γ),体内IFN-γ的浓度明显增高。而在缺乏T细胞的裸鼠体内做了同样的实验,荷瘤后进行CTX化疗,结果发现,接受化疗的荷瘤裸鼠的骨髓、脾脏和外周血中MDSCs的比例与未接受化疗的肿瘤裸鼠相比并未出现明显上升。接下来的T细胞与MDSCs的体外共培养实验以及单抗阻断等实验也证实,T细胞能够促进MDSCs的存活与增殖,并且这种促进作用主要由T细胞分泌的IFN-γ介导。上述结果提示,环磷酰胺化疗能够引起肿瘤小鼠体内CD4+和CD8+T细胞的增殖与活化,IFN-γ分泌水平增加,而这些大量生成的IFN-γ诱导了化疗后的肿瘤小鼠体内MDSCs的比例进一步上升。这一研究有助于揭示环磷酰胺化疗引起MDSCs比例升高的机制,这将为人们更好地应用环磷酰胺,探索如何使其在发挥细胞毒作用的同时能起到增强抗肿瘤的免疫效应等方面提供指导。
[Abstract]:The inhibition of MDSCs cells of myeloid origin (Myeloid-derived suppressor, cells, MDSCs) is a heterogeneous population of cells to the negative immune regulation function is, composed of myeloid cells at early stages of differentiation, phenotype of MDSCs in mice was Gr-1+CD11b+. in tumor, chronic infection, trauma and stress and other pathological conditions. This group of cells in the bone marrow, spleen, lymph node, peripheral blood and accumulation occurred in parts of the disease.
In the animal model of tumor and tumor patients, accumulate MDSCs in the part above is mainly due to the proliferation of tumor cells in the process of many cytokines such as granulocyte monocyte colony-stimulating factor (GM-CSF), vascular endothelial growth factor (VEGF), interleukin (IL-6) induced studies. MDSCs, the secretion of arginase (Arginase 1), inducible nitric oxide synthase 2 (iNOS2) and the secretion of inhibitory cytokines such as transforming growth factor beta (TGF-p) and other ways to inhibit T lymphocyte function and show strong immunosuppressive effects, especially the inhibition of CD8+T cell function, inhibition this causes tumor cells to escape immune recognition and immune system destruction. At the same time, the infiltration in tumor site MDSCs also can release metal matrix protein enzyme -9 (MMP-9) and metal matrix The proteinase -13 (MMP-13) promotes the formation of tumor vessels and the growth, infiltration and metastasis of tumor, which is more beneficial to the development of tumor.
Cyclophosphamide (CTX) as a kind of alkylating drugs can kill tumor cells directly, has been widely used in tumor chemotherapy. However, the study found that cancer patients after chemotherapy with cyclophosphamide in bone marrow, and the proportion of missed spleen and peripheral blood MDSCs cells from patients with cancer chemotherapy compared to the more high. This situation is also found in tumor mouse model of cyclophosphamide chemotherapy. The chemotherapy effect caused by cyclophosphamide MDSCs increased ratio is obviously not conducive to cyclophosphamide anti-tumor effect.
Through the interaction between the immune cells to regulate host immune response of the whole, we speculate that the proportion of MDSCs increased after CTX chemotherapy may be T cells promote. The causes and mechanism of MDSCs increased the proportion for the understanding of CTX after chemotherapy, we experimentally compared cyclophosphamide therapy for metastatic tumor in mice (4T1 mice model of breast cancer) and without immunosuppressive chemotherapy tumor microenvironment in mice the differences found in the early MDSCs cyclophsphamide after chemotherapy has not yet significantly increased, CD4+T cells and CD8+T cells had obvious amplification and produces large amounts of interferon gamma (IFN- y), concentrations of IFN- gamma were significantly increased. And do the same experiment in in the absence of T cells in nude mice, CTX chemotherapy, tumor bearing nude mice found that received chemotherapy of MDSCs bone marrow, spleen and peripheral blood and the proportion of non treated tumor in nude The rat did not appear significantly increased. Compared with MDSCs T cells following in vitro co culture assay and monoclonal antibody blocking experiments also confirmed that T cells could promote the survival and proliferation of MDSCs, and this effect mainly by promoting IFN- mediated gamma secretion in T cells. These results suggest that cyclophosphamide chemotherapy can lead to cancer in mice CD4+ and CD8+T cell proliferation and activation of IFN- secretion levels increased, and these generated IFN- gamma induced by chemotherapy in mice with tumor MDSCs ratio to rise further.
This study helps to reveal the mechanism of increased MDSCs ratio induced by cyclophosphamide chemotherapy, which will provide guidance for people to better use cyclophosphamide, explore how to make it play a cytotoxic role and enhance the anti-tumor immune effect.

【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：R392

【共引文献】