浆细胞样树突状细胞对弓形虫感染急性炎症中免疫应答的影响

发布时间：2018-02-14 20:18

本文关键词： 浆细胞样树突状细胞刚地弓形虫 CD4~+T细胞过度极化　出处：《山东农业大学》2017年硕士论文　论文类型：学位论文

【摘要】：刚地弓形虫是一种专性细胞内寄生虫,感染免疫功能正常的宿主通常无症状,在免疫缺陷或者先天性感染的宿主中可成为致死性的机会致病原虫。树突状细胞(Dendritic Cells,DCs)是机体在弓形虫感染早期最先产生应答的固有免疫细胞之一,DCs作为免疫系统中最重要的抗原提呈细胞,可以活化T细胞,启动宿主的获得性免疫反应,是连接固有免疫和适应性免疫的桥梁。DCs是高度异质性细胞群体,包含多种亚群。由于DCs的生物学效应的发挥取决于其细胞类型和数量,因此研究DCs亚群在抗弓形虫感染中的作用成为本领域研究的热点。树突状细胞可以分为经典性树突状细胞(Conventional dendritic cells,cDCs)和浆细胞样树突状细胞(Plcasmacytiod Dendritic Cells,pDCs)。pDCs是DCs的一个独特亚群,在不同微环境下可以选择性的诱导免疫应答也可以诱导免疫耐受。近来有文献报道pDCs在弓形虫感染时可以识别弓形虫的抗原,将弓形虫的抗原提呈给T细胞,以启动适应性免疫应答。清除pDCs增加了TRL11-/-基因缺陷小鼠对弓形虫的易感性。但是pDCs在弓形虫感染引起的急性炎症中对固有免疫和适应性免疫反应的影响机制仍不十分清楚,因此,本课题应用现代免疫学方法并结合使用pDCs条件性基因敲除小鼠,力图阐明pDCs在抗弓形虫感染中对固有免疫和适应性免疫细胞的调控机制。该研究有助于更好的理解pDCs在感染免疫中的作用和贡献,为研发有效的抗弓形虫树突状细胞疫苗提供新的靶点。本研究主要是通过以下几个方面进行并且得到如下结果:1.pDCs缺失增加了小鼠对弓形虫的易感性本研究使用BDCA2-DTR小鼠腹腔注射DT,特异性清除pDCs,随后腹腔感染弓形虫速殖子后,感染三天后发现,清除pDCs的小鼠与对照组相比极大的增强了对弓形虫的易感性,脾脏肿大,死亡率增加了45%。该结果提示pDCs在抗弓形虫感染中起到非常重要的作用。2.pDCs缺失导致了IL-12分泌减少检测感染小鼠血清中分泌的IL-12发现,与对照组相比pDCs缺失小鼠IL-12p40分泌显著性减少,IL-12p70未检测到。该结果提示pDCs在IL-12的合成和分泌中起到调控作用。3.pDCs缺失加重了弓形虫感染导致的Th1型细胞因子分泌检测感染小鼠血清中分泌的Th1型细胞因子水平发现,高分泌的IFN-γ、IL-6、TNF-α、在pDCs缺失后显著性的增加了。该结果提示pDCs缺失引起了Th1型细胞因子风暴。4.pDCs缺失影响巨噬细胞和cDCs细胞数量检测感染小鼠脾脏的效应细胞发现,pDCs缺失并不影响固有免疫细胞中的中性粒细胞、炎症性单核细胞数量。但是引起巨噬细胞、cDCs数量显著性减少。进一步分析cDCs的两个亚群CD8+DCs和CD11b+DCs的变化发现,pDCs缺失主要引起了CD8+DCs的比例和数量显著性减少。对适应性免疫细胞CD4+T、CD8+T细胞检测发现,弓形虫感染导致了T细胞显著性减少,pDCs缺失并不影响T细胞数量。该结果提示pDCs和巨噬细胞、CD8+DCs存在交叉对话。5.pDCs缺失引起CD4+T细胞过度极化对体内主要分泌IFN-γ的细胞检测发现,弓形虫感染3天后,IFN-γ主要是由CD4+T细胞分泌的,pDCs缺失不影响NK细胞分泌的IFN-γ,IFN-γ阳性的CD4+T比例和数量均显著性增加,CD8+T比例著性增加,但是细胞数量显著性减少。该结果提示pDCs缺失导致了CD4+T细胞过度活化。综上所述,得出如下结论:pDCs影响IL-12的分泌,在早期抗弓形虫感染中起到保护性作用,影响固有免疫细胞中的巨噬细胞、CD8+DCs的细胞数量,影响适应性免疫细胞中CD4+T分泌IFN-γ的能力,影响Th1型细胞因子分泌。
[Abstract]:Toxoplasma gondii is an obligate intracellular parasite infection in immunocompetent hosts are usually asymptomatic, or congenital infection in immunocompromised hosts can become lethal opportunistic protozoan. Dendritic cells (Dendritic Cells DCs) is one of the body's innate immune cells in early first response to Toxoplasma infection DCs, as the most important immune system in antigen-presenting cells and can activate T cells, initiating host acquired immune responses,.DCs is a bridge between innate immunity and acquired immunity is a highly heterogeneous cell population contains multiple subsets. The biological effects of DCs depends on the cell type and quantity. The role of DCs subsets in anti Toxoplasma gondii infection has become a hot research in this field. Dendritic cells can be divided into classical dendritic cells (Conventional dendritic cell S, cDCs) and plasmacytoid dendritic cells (Plcasmacytiod Dendritic Cells, pDCs.PDCs DCs) is a unique subtype, can induce immune response selectivity can also induce immune tolerance in different micro environment. It has recently been reported in pDCs of Toxoplasma gondii infection can identify Toxoplasma antigens of Toxoplasma gondii the antigens to T cells to initiate adaptive immune responses. PDCs clearance increased susceptibility to Toxoplasma gondii TRL11-/- gene deficient mice. But pDCs in acute inflammation caused by the infection of Toxoplasma gondii in the effect and the mechanism of innate and adaptive immune response is still not very clear, therefore, the application of modern immunology method combined with the use of pDCs conditional knockout mice, to clarify pDCs in anti Toxoplasma gondii infection on innate and adaptive immune cell regulation mechanism. The study is very helpful to science The solution and the contribution of pDCs in infectionimmunity, for the development of effective anti Toxoplasma dendritic cell vaccines provide a new target. This research is mainly through the following aspects and results are as follows: 1.pDCs deletion increased susceptibility to Toxoplasma gondii in mice in this study using BDCA2-DTR mice by intraperitoneal injection of DT, specific clearance pDCs, then the abdominal infection of Toxoplasma gondii infection after three days found that the clearance of pDCs mice compared with the control group greatly enhanced the susceptibility to Toxoplasma gondii, splenomegaly, mortality increased 45%. the results of pDCs in anti Toxoplasma infection plays a very important role in.2.pDCs deletion led to IL-12 reduce the secretion of IL-12 secretion in infected mice was measured in serum showed that compared with the control group pDCs deficient mice significantly reduced the secretion of IL-12p40 and IL-12p70 were not detected. The results suggest that pDCs in IL-12 The synthesis and secretion of play a regulatory role in.3.pDCs deletion aggravated the Toxoplasma infection of Th1 type cytokines leads to the secretion of Th1 type cytokines secreted by detection of infected mice found in serum, IFN- gamma, hypersecretion of IL-6, TNF- alpha, in after deletion of pDCs was significantly increased. The results suggest that pDCs deficiency caused Th1 type cytokine storm.4.pDCs deletion effect cell number of macrophages and cDCs cells were detected in infected mice spleen showed that pDCs deletion did not affect neutrophil innate immune cells, the number of inflammatory mononuclear cells by macrophages. However, the number of cDCs significantly reduced. Changes are found in the further analysis of cDCs two subsets of CD8+DCs and CD11b+DCs, pDCs deletion is mainly caused by the CD8+DCs number and the proportion were significantly reduced. The adaptive immune cells CD4+T, CD8+T cell detection of Toxoplasma gondii infection Guide Due to the significant decrease of T cells, pDCs deletion did not affect the number of T cells. The results suggest that pDCs and CD8+DCs macrophages, the cross-talk between.5.pDCs cells that detect CD4+T cell loss caused by excessive polarization on the main body of IFN- secretion, 3 days after infection with Toxoplasma gondii, IFN- gamma is mainly secreted by CD4+T cells, deletion of pDCs does not effects of IFN- gamma NK cells, IFN- positive ratio of CD4+T and the number were significantly increased, the proportion of CD8+T increased significantly, but the number of cells significantly reduced. The results suggest that pDCs deficiency led to the excessive activation of CD4+T cells. In summary, draw the following conclusions: influence the secretion of IL-12 pDCs, in the early stage of anti Toxoplasma infection to play a protective effect, effect of innate immune cells in macrophages, the number of CD8+DCs cells and the effect of CD4+T in adaptive immune cells to secrete IFN-, effect of Th1 type cytokines Secrete.

【学位授予单位】：山东农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S855.9

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