约氏疟原虫感染小鼠巨噬细胞活化和效应特点的研究
发布时间：2018-08-29 19:54
【摘要】： 前言 疟疾是全球关注、高发的感染性疾病。Nature最新报道显示，截止2002年，世界感染疟疾的患者人数达5.15亿，全球受威胁人口达22亿。为此，WHO将艾滋病、结核和疟疾列为三类优先重点防治的感染性疾病。目前，疟疾疫苗和抗疟新药的研制与开发是有效控制疟疾发生和发展的重要战略，其必需的前提基础有赖于对宿主保护性免疫应答机制的进一步阐明。 单核-巨噬细胞在不同方面明显影响着疟原虫的感染过程，它既可作为非特异免疫系统细胞发挥非特异性吞噬、杀伤作用，也可参与介导特异性免疫应答，发挥抗原提呈和免疫调节的重要作用。大量研究表明，红内期保护性免疫应答的鲜明特点是Th1和Th2型免疫应答的有序活化，由CD_4~+Yh细胞和抗体共同参与。感染急性期以IFN-γ为主导的Th1型炎症性细胞因子活化巨噬细胞等免疫效应细胞，遏制疟原虫在红内期的爆发性增殖，有效控制原虫血症的迅速上升：随后应答向Th2型过渡，最终以抗体介导的免疫效应彻底清除疟原虫。我们的前期研究已证实，活化的单核-巨噬细胞在约氏疟原虫感染早期可能是遏制虫体血症水平的关键因素之一。因此，有必要对巨噬细胞在整个感染过程中的活化规律和效应特点进行更深一步探讨和阐明。 本研究选用P．y 17XL抵抗型DBA／2小鼠为研究对象，首次全程动态观察巨噬细胞表面膜分子、效应分子NO含量及其吞噬功能的变化，以期进一步阐明在疟疾感染中巨噬细胞的活化规律和效应特点，旨在为有效疟疾疫苗和抗疟新药的研制、开发提供新的理论和实验依据。 实验材料与方法 本研究选用P．y 17XL抵抗型DBA／2小鼠为研究对象。Giemsa薄血膜染色，光学显微镜计数红细胞感染率；流式细胞技术动态检测DBA／2小鼠在P．y 17XL感染过程中，脾巨噬细胞数量，表面膜分子CD36、CD64和MHCⅡ的表达水平；通过Griess反应，测定脾巨噬细胞分泌NO_2~-的含量；显微镜检巨噬细胞的吞噬功能。数据以均值士标准差((?)±s)表示，数据经t检验，P＜0.05为差异显著。 实验结果 DBA／2小鼠在P．y 17XL攻击后原虫血症缓慢上升，于感染后第7d达到峰值后逐渐降低，在感染后约第15d小鼠自愈，疟原虫感染的红细胞被全部清除；于急性感染早期(3d-5d)，脾巨噬细胞NO分泌水平出现有意义的升高，继而巨噬细胞吞噬能力于感染后第5d开始增强，至感染后第10d吞噬率高达95％，随之持续维持于高水平；脾巨噬细胞表面MHCⅡ类分子和CD36于感染后第3d开始升高，至感染后第10d分别达到峰值；CD64表达水平于感染后第5d开始升高，随后持续维持于高水平；并且，巨噬细胞数量也于感染后第3d开始明显增加，至第10d达到峰值。 讨论 近年来，许多研究表明天然免疫和获得性免疫应答参与控制红内期疟原虫感染，减轻原虫负荷，延缓发展为重症疟疾的感染进程。巨噬细胞具有显著的非特异性吞噬和杀伤能力，经其有效的刺激因子IFN-γ活化后其功能可进一步增强。以往报道显示，体液循环的单核细胞和组织中(肝、脾)的巨噬细胞能够通过清除受疟原虫感染的红细胞(PRBC)参与控制疟原虫感染。我们的前期研究也已证实，抵抗型DBA／2小鼠CD_4~+Th1细胞于感染早期可产生高水平的IFN-γ，活化的巨噬细胞具有重要的红内期疟原虫增殖抑制效应。在此，本研究利用P．y 17XL抵抗型DBA／2小鼠模型，，系统地观察了巨噬细胞在P．y 17XL感染过程中的活化规律和效应特点。实验结果显示，在P．y 17XL感染过程中，巨噬细胞于感染早期迅速活化，以分泌效应分子NO抑制原虫血症及非特异性吞噬方式杀伤疟原虫。由此提示， 巨噬细胞是DBA／2小鼠产生抗疟保护性免疫应答的重要效应细胞。 以往研究显示，作为专职抗原提呈细胞，巨噬细胞可通过表达MHC分子和共刺激分子提呈抗原给T细胞，为T细胞活化提供必要的活化信号并控制T细胞的分化方向从而影响疟疾的感染结局。MHCⅡ类分子是巨噬细胞活化的重要标志。MHCⅡ敲除鼠研究显示，非致死型约氏疟原虫和夏氏疟原虫感染红内期的保护性免疫完全依赖于MHCⅡ类分子。BALB／c小鼠感染非致死型约氏疟原虫后，巨噬细胞表达MHCⅡ和CD80的水平明显增加，从而促进T细胞活化和IFN-γ的分泌。本研究进一步发现，P．y 17XL感染早期巨噬细胞MHCⅡ类分子表达水平明显增强，同时伴随巨噬细胞数量的显著增加。提示巨噬细胞在IFN-γ刺激作用下发生了有效活化，活化的单核．巨噬细胞参与DBA／2小鼠Th1型免疫应答的有效建立。 已证实，巨噬细胞是非特异性免疫效应分子NO的重要来源，NO氧化后形成的过氧化氮是巨噬细胞发挥杀伤毒性的主要效应分子。体外实验显示，NO在红内期发挥细胞毒性和原虫生长抑制作用。尽管NO在抗红内期疟原虫免疫机制中的作用尚存争议，但是我们前期研究已经发现，约氏疟原虫感染早期随着DBA／2小鼠NO合成的增加，红细胞感染率不断上升的趋势受到遏制，并可见网织红细胞的表面出现许多裂殖子附着现象。推测可能是因为感染早期NO合成水平的提高使大量裂殖子对红细胞侵袭能力发生障碍。本研究结果显示，尽管DBA／2小鼠于感染后前4d巨噬细胞尚未表现吞噬作用，但小鼠脾细胞培养上清中NO水平于感染后第3d即出现显著升高。与此同时，原虫血症水平呈现缓慢上升趋势。由此提示，在疟疾感染早期巨噬细胞可通过合成分泌NO发挥原虫抑制作用。 巨噬细胞的非特异性吞噬包括非调理性吞噬和调理性吞噬两种机制。巨噬细胞的非调理性吞噬通过识别病原体表面模式识别受体包括清道夫受体和甘露糖受体完成。CD36是清道夫受体家族B型受体，目前认为CD36在介导巨噬细胞非调理性吞噬功能中发挥重要作用。一些研究显示，CD36与疟原虫感染红细胞的结合影响疟疾发病的严重程度。CD36表达缺陷与重症疟疾(尤其是脑疟)关系密切。上调巨噬细胞表面CD36分子后，人及C57BL／6、BALB／c小鼠的巨噬细胞对疟原虫感染红细胞的吞噬活性明显增强；而应用抗CD36单克隆抗体后其吞噬能力下降。通过受体阻断和CD36基因敲除的研究发现：在体外缺乏调理作用的情况下，人和小鼠的巨噬细胞均能吞噬疟原虫环状体期感染的红细胞(RPEs)，此作用依赖于巨噬细胞表面的CD36分子，而非其它表面受体(ICAM-1，αvβ3，或PECAM-1或模式识别受体如甘露糖受体或CD14)；此外，在单核巨噬细胞对恶性疟原虫配子体的清除中CD36亦发挥关键的天然免疫防御作用。本研究通过全程动态观察发现，在P．y 17XL抵抗型DBA／2小鼠自然感染过程中，巨噬细胞表面CD36分子从感染后第3d表达水平开始明显升高，随感染进程至第10d达到峰值，相应巨噬细胞吞噬能力明显增强。由此提示，疟疾感染早期巨噬细胞可能通过CD36发挥非调理性吞噬作用。 疟疾红内期保护性免疫应答经过急性期感染阶段后，最终要由特异性抗体介导的免疫应答清除疟原虫。抗体介导的调理性吞噬可能是疟原虫感染红内期获得性免疫应答重要机制之一。利用Carrageenan(巨噬细胞抑制剂)研究发现，抗体依赖的FcR介导的调理性吞噬杀伤是清除P．berghei XAT红内期感染的关键，提示脾巨噬细胞的吞噬活性对宿主抵抗疟疾感染十分必要。FcRγ-／-(γ链敲除)小鼠由于缺乏抗体依赖性吞噬和抗体依赖的细胞毒作用(ADCC)，对P．berghei XAT易感性明显增强并最终死亡。Mota等证实，CBA小鼠外周血巨噬细胞能够对夏氏疟原虫(P．chabaudi chabaudi)感染红细胞发挥抗体介导的调理性吞噬作用，且具有虫株特异性。我们的前期研究显示，DBA／2小鼠在致死型约氏疟原虫感染后第10d疟原虫特异性IgG抗体水平升高。本研究检测到巨噬细胞表面的FcγRⅠ(CD64)从感染后第5d表达水平开始升高，随后逐渐上升并持续维持较高水平。与此同时，巨噬细胞吞噬率在感染第8-15d处于高水平。由此提示，在约氏疟原虫感染后期，伴随特异性抗体的产生，巨噬细胞可能通过CD64发挥调理性吞噬作用。 综上，本研究通过全程、动态、系统的观察抵抗型DBA／2小鼠的巨噬细胞在P．y 17XL自然感染过程中的活化及效应特点，进一步揭示了巨噬细胞无论在抗疟原虫感染的天然免疫和获得性免疫中均发挥重要作用。巨噬细胞活化和效应特点及其相关机制的进一步阐明，必将为有效的疟疾疫苗和抗疟新药的研制开发提供必要的理论和实验依据。 结论 在致死型约氏疟原虫感染过程中，巨噬细胞无论在天然免疫和获得性免疫中均发挥重要的作用。 1．DBA／2小鼠脾巨噬细胞的数量呈现逐步升高的动态变化趋势； 2．通过MHCⅡ类分子表达，提示巨噬细胞在IFN-γ刺激作用下发生了有效活化； 3．巨噬细胞表达的清道夫受体CD36在感染早期显著增加，介导非调理性吞噬杀伤作用； 4．作为巨噬细胞表达的FcγRI(CD64)在感染后期的显著增加，可能参与抗体介导的调理性吞噬杀伤作用； 5．巨噬细胞分泌NO的水平于感染早期出现有意义的升高，由此抑制疟原虫的爆发性增殖。
[Abstract]:Preface
Malaria is a global concern and a high incidence of infectious diseases. According to the latest report from Nature, the number of people infected with malaria in the world reached 515 million by 2002, and the number of people threatened worldwide reached 2.2 billion. It is an important strategy to effectively control the occurrence and development of malaria, and its necessary prerequisite depends on the further elucidation of the host protective immune response mechanism.
Monocyte-macrophage plays a significant role in the infection process of Plasmodium in different aspects. It can not only act as a non-specific immune system cell to perform non-specific phagocytosis and kill, but also participate in the mediation of specific immune response and play an important role in antigen presentation and immune regulation. It is characterized by the orderly activation of Th1 and Th2 immune responses, with the participation of CD_4~+Yh cells and antibodies. In the acute phase of infection, IFN-gamma-dominated Th1 inflammatory cytokines activate immune effector cells such as macrophages, inhibit the explosive proliferation of Plasmodium in the intraerythrocytic phase, effectively control the rapid rise of protozoemia: the subsequent response to Th Our previous studies have shown that activated monocytes and macrophages may be one of the key factors to control the level of parasitemia in the early stage of Plasmodium yoelii infection. Further explore and clarify.
In this study, P.y 17XL-resistant DBA/2 mice were selected as the research objects. The changes of membrane molecules, NO content and phagocytic function of macrophages were observed for the first time. The aim of this study was to further clarify the activation rules and effect characteristics of macrophages in malaria infection, and to develop effective malaria vaccines and new antimalarial drugs. Development provides new theoretical and experimental basis.
Experimental materials and methods
In this study, P.y 17XL-resistant DBA/2 mice were selected as the research objects.Giemsa thin blood membrane staining and light microscopy were used to count the infection rate of red blood cells.Flow cytometry was used to detect the number of splenic macrophages and the expression levels of surface membrane molecules CD36, CD64 and MHC II during P.y 17XL infection in DBA/2 mice. The content of NO_2~- secreted by splenic macrophages and the phagocytic function of macrophages were examined by microscope.
experimental result
In DBA/2 mice, the level of protozomia increased slowly after P.y 17XL attack, decreased gradually after 7 days of infection, and all the erythrocytes infected by P.falciparum were cleared after 15 days of infection. In the early stage of acute infection (3-5 days), the level of NO secreted by splenic macrophages increased significantly, and then the phagocytic capacity of macrophages increased. The phagocytosis rate was as high as 95% on the 5th day after infection, and then remained at a high level on the 10th day after infection; the MHC class II molecule and CD36 on the surface of splenic macrophages began to increase on the 3rd day after infection and reached their peak value on the 10th day after infection; the expression of CD64 began to increase on the 5th day after infection, and then remained at a high level. The number of macrophages also increased significantly at 3D after infection and reached the peak at 10d.
discuss
In recent years, many studies have shown that innate and acquired immune responses participate in the control of erythrocytic malaria infection, reduce the burden of parasites, and delay the development of severe malaria infection. Previous studies have shown that monocytes circulating in body fluid and macrophages in tissues (liver, spleen) can participate in the control of malaria infection by eliminating the erythrocytes (PRBC) infected by Plasmodium. Our previous studies have also confirmed that CD_4~+Th1 cells of resistant DBA/2 mice can produce high levels of IFN-gamma in the early stage of infection, and activated macrophages possess high levels of IFN-gamma. In this study, the activation of macrophages during P.y 17XL infection was systematically observed in a P.y 17XL resistant DBA/2 mouse model. The results showed that macrophages were activated rapidly in the early stage of P.y 17XL infection in order to produce secretory effects. The molecule NO inhibits protozoa and non-specific phagocytosis to kill Plasmodium.
Macrophages are important effector cells in DBA / 2 mice producing antimalarial protective immune responses.
Previous studies have shown that as full-time antigen presenting cells, macrophages can present antigens to T cells by expressing MHC molecules and costimulatory molecules, providing necessary activation signals for T cell activation and controlling the direction of T cell differentiation, thereby affecting the outcome of malaria infection. MHC class II molecules are important markers of macrophage activation. The protective immunity of non-lethal Plasmodium yoelii and Plasmodium charantii during intraerythrocytic infection was completely dependent on MHC class II molecules. The expression of MHC class II and CD80 in macrophages of BALB/c mice infected with non-lethal Plasmodium yoelii increased significantly, thus promoting the activation of T cells and the secretion of IFN-gamma. The expression of MHC class II molecule in macrophages at the early stage of Y 17XL infection was significantly increased, accompanied by a significant increase in the number of macrophages, suggesting that macrophages were effectively activated and activated by IFN-gamma stimulation.
It has been proved that macrophages are an important source of non-specific immune effector molecule NO. Nitrogen peroxide formed after NO oxidation is the main effector molecule for macrophages to exert cytotoxicity and protozoan growth inhibition during the erythrocytic phase. Although the role of NO in the immune mechanism of anti-erythrocytic phase Plasmodium It is controversial, but our previous studies have found that in the early stage of Plasmodium yoelii infection, with the increase of nitric oxide synthesis in DBA/2 mice, the rising trend of erythrocyte infection rate was restrained, and many merozoite attachments on reticulocyte surface were observed. The results showed that although the macrophages of DBA/2 mice did not show phagocytosis at the first 4 days after infection, the NO level in the supernatant of spleen cells increased significantly at the third day after infection. Meanwhile, the level of protozoaemia increased slowly, suggesting that malaria infection was present. Early macrophages can inhibit protozoa by secreting NO.
Non-specific phagocytosis of macrophages includes two mechanisms: irrational phagocytosis and regulatory phagocytosis. Irregular phagocytosis of macrophages is accomplished by recognizing pathogen surface pattern recognition receptors including scavenger receptors and mannose receptors. CD36 is a scavenger receptor family B-type receptor. It is currently believed that CD36 mediates macrophage non-regulation. Some studies have shown that the binding of CD36 to erythrocytes infected by Plasmodium falciparum affects the severity of malaria. The deficiency of CD36 expression is closely related to severe malaria, especially cerebral malaria. The phagocytic activity of human and mouse macrophages was markedly increased, while that of anti-CD36 monoclonal antibody was decreased. Receptor blockade and CD36 gene knockout studies showed that both human and mouse macrophages could phagocytize erythrocytes (RPEs) infected by Plasmodium in the circular phase in vitro, depending on macrophages. CD36 molecules on the surface, rather than other surface receptors (ICAM-1, alpha v beta 3, or PECAM-1 or pattern recognition receptors such as mannose receptors or CD14), also play a key role in innate immune defense against P.falciparum gametophyte clearance by monocytes and macrophages. During the natural infection of mice, the expression of CD36 on the surface of macrophages began to increase significantly from the 3rd day after infection, and the phagocytic capacity of corresponding macrophages increased significantly with the peak of CD36 expression on the 10th day after infection.
The protective immune response in the erythrocytic phase of malaria passes through the acute phase of infection and is eventually cleared of the parasite by a specific antibody-mediated immune response. The antibody-mediated regulatory phagocytosis may be one of the important mechanisms of the acquired immune response in the erythrocytic phase of malaria infection. FcR-mediated regulatory phagocytosis is the key to eliminating P.berghei XAT intraerythrocytic infection, suggesting that phagocytic activity of splenic macrophages is essential for host resistance to malaria infection. FcR gamma-/-(gamma chain knockout) mice are susceptible to P.berghei XAT due to lack of antibody-dependent phagocytosis and antibody-dependent cytotoxicity (ADCC). Mota et al. confirmed that the peripheral blood macrophages of CBA mice could exert antibody-mediated regulatory phagocytosis against P. chabaudi-chabaudi-infected erythrocytes and possess the specificity of the strain. Our previous study showed that DBA/2 mice had specific IgG against P. chabaudi-infected erythrocytes on the 10th day after the deadly P. yoelii infection. The expression of Fc gamma R I (CD64) on the surface of macrophages began to increase from the 5th day after infection, then gradually increased and maintained a high level. At the same time, the phagocytosis rate of macrophages was at a high level from the 8th to 15th day after infection. Macrophages may play a regulatory phagocytosis role through CD64.
In conclusion, this study systematically and dynamically observed the activation and effect of macrophages in resistant DBA/2 mice during natural infection of P.y 17XL, and further revealed that macrophages play an important role in both innate and acquired immunity against malaria infection. Further elucidation of the relevant mechanisms will provide necessary theoretical and experimental basis for the development of effective malaria vaccines and new antimalarial drugs.
conclusion
Macrophages play an important role in both innate and acquired immunity in the process of lethal Plasmodium yoelii infection.
The number of splenic macrophages in 1.DBA / 2 mice increased gradually.
2. the expression of MHC class II molecules indicated that macrophages were activated effectively under the stimulation of IFN- gamma.
3. The expression of scavenger receptor CD36 in macrophages increased significantly in the early stage of infection, which mediated the irrational phagocytosis.
4. Fc gamma RI (CD64), as a macrophage expression, increased significantly in the late stage of infection, which may be involved in antibody-mediated regulatory phagocytosis.
5. The level of NO secreted by macrophages increased significantly in the early stage of infection, thus inhibiting the outbreak of Plasmodium.
【学位授予单位】：中国医科大学
【学位级别】：硕士
【学位授予年份】：2007
【分类号】：R392
本文编号：2212245
[Abstract]:Preface
Malaria is a global concern and a high incidence of infectious diseases. According to the latest report from Nature, the number of people infected with malaria in the world reached 515 million by 2002, and the number of people threatened worldwide reached 2.2 billion. It is an important strategy to effectively control the occurrence and development of malaria, and its necessary prerequisite depends on the further elucidation of the host protective immune response mechanism.
Monocyte-macrophage plays a significant role in the infection process of Plasmodium in different aspects. It can not only act as a non-specific immune system cell to perform non-specific phagocytosis and kill, but also participate in the mediation of specific immune response and play an important role in antigen presentation and immune regulation. It is characterized by the orderly activation of Th1 and Th2 immune responses, with the participation of CD_4~+Yh cells and antibodies. In the acute phase of infection, IFN-gamma-dominated Th1 inflammatory cytokines activate immune effector cells such as macrophages, inhibit the explosive proliferation of Plasmodium in the intraerythrocytic phase, effectively control the rapid rise of protozoemia: the subsequent response to Th Our previous studies have shown that activated monocytes and macrophages may be one of the key factors to control the level of parasitemia in the early stage of Plasmodium yoelii infection. Further explore and clarify.
In this study, P.y 17XL-resistant DBA/2 mice were selected as the research objects. The changes of membrane molecules, NO content and phagocytic function of macrophages were observed for the first time. The aim of this study was to further clarify the activation rules and effect characteristics of macrophages in malaria infection, and to develop effective malaria vaccines and new antimalarial drugs. Development provides new theoretical and experimental basis.
Experimental materials and methods
In this study, P.y 17XL-resistant DBA/2 mice were selected as the research objects.Giemsa thin blood membrane staining and light microscopy were used to count the infection rate of red blood cells.Flow cytometry was used to detect the number of splenic macrophages and the expression levels of surface membrane molecules CD36, CD64 and MHC II during P.y 17XL infection in DBA/2 mice. The content of NO_2~- secreted by splenic macrophages and the phagocytic function of macrophages were examined by microscope.
experimental result
In DBA/2 mice, the level of protozomia increased slowly after P.y 17XL attack, decreased gradually after 7 days of infection, and all the erythrocytes infected by P.falciparum were cleared after 15 days of infection. In the early stage of acute infection (3-5 days), the level of NO secreted by splenic macrophages increased significantly, and then the phagocytic capacity of macrophages increased. The phagocytosis rate was as high as 95% on the 5th day after infection, and then remained at a high level on the 10th day after infection; the MHC class II molecule and CD36 on the surface of splenic macrophages began to increase on the 3rd day after infection and reached their peak value on the 10th day after infection; the expression of CD64 began to increase on the 5th day after infection, and then remained at a high level. The number of macrophages also increased significantly at 3D after infection and reached the peak at 10d.
discuss
In recent years, many studies have shown that innate and acquired immune responses participate in the control of erythrocytic malaria infection, reduce the burden of parasites, and delay the development of severe malaria infection. Previous studies have shown that monocytes circulating in body fluid and macrophages in tissues (liver, spleen) can participate in the control of malaria infection by eliminating the erythrocytes (PRBC) infected by Plasmodium. Our previous studies have also confirmed that CD_4~+Th1 cells of resistant DBA/2 mice can produce high levels of IFN-gamma in the early stage of infection, and activated macrophages possess high levels of IFN-gamma. In this study, the activation of macrophages during P.y 17XL infection was systematically observed in a P.y 17XL resistant DBA/2 mouse model. The results showed that macrophages were activated rapidly in the early stage of P.y 17XL infection in order to produce secretory effects. The molecule NO inhibits protozoa and non-specific phagocytosis to kill Plasmodium.
Macrophages are important effector cells in DBA / 2 mice producing antimalarial protective immune responses.
Previous studies have shown that as full-time antigen presenting cells, macrophages can present antigens to T cells by expressing MHC molecules and costimulatory molecules, providing necessary activation signals for T cell activation and controlling the direction of T cell differentiation, thereby affecting the outcome of malaria infection. MHC class II molecules are important markers of macrophage activation. The protective immunity of non-lethal Plasmodium yoelii and Plasmodium charantii during intraerythrocytic infection was completely dependent on MHC class II molecules. The expression of MHC class II and CD80 in macrophages of BALB/c mice infected with non-lethal Plasmodium yoelii increased significantly, thus promoting the activation of T cells and the secretion of IFN-gamma. The expression of MHC class II molecule in macrophages at the early stage of Y 17XL infection was significantly increased, accompanied by a significant increase in the number of macrophages, suggesting that macrophages were effectively activated and activated by IFN-gamma stimulation.
It has been proved that macrophages are an important source of non-specific immune effector molecule NO. Nitrogen peroxide formed after NO oxidation is the main effector molecule for macrophages to exert cytotoxicity and protozoan growth inhibition during the erythrocytic phase. Although the role of NO in the immune mechanism of anti-erythrocytic phase Plasmodium It is controversial, but our previous studies have found that in the early stage of Plasmodium yoelii infection, with the increase of nitric oxide synthesis in DBA/2 mice, the rising trend of erythrocyte infection rate was restrained, and many merozoite attachments on reticulocyte surface were observed. The results showed that although the macrophages of DBA/2 mice did not show phagocytosis at the first 4 days after infection, the NO level in the supernatant of spleen cells increased significantly at the third day after infection. Meanwhile, the level of protozoaemia increased slowly, suggesting that malaria infection was present. Early macrophages can inhibit protozoa by secreting NO.
Non-specific phagocytosis of macrophages includes two mechanisms: irrational phagocytosis and regulatory phagocytosis. Irregular phagocytosis of macrophages is accomplished by recognizing pathogen surface pattern recognition receptors including scavenger receptors and mannose receptors. CD36 is a scavenger receptor family B-type receptor. It is currently believed that CD36 mediates macrophage non-regulation. Some studies have shown that the binding of CD36 to erythrocytes infected by Plasmodium falciparum affects the severity of malaria. The deficiency of CD36 expression is closely related to severe malaria, especially cerebral malaria. The phagocytic activity of human and mouse macrophages was markedly increased, while that of anti-CD36 monoclonal antibody was decreased. Receptor blockade and CD36 gene knockout studies showed that both human and mouse macrophages could phagocytize erythrocytes (RPEs) infected by Plasmodium in the circular phase in vitro, depending on macrophages. CD36 molecules on the surface, rather than other surface receptors (ICAM-1, alpha v beta 3, or PECAM-1 or pattern recognition receptors such as mannose receptors or CD14), also play a key role in innate immune defense against P.falciparum gametophyte clearance by monocytes and macrophages. During the natural infection of mice, the expression of CD36 on the surface of macrophages began to increase significantly from the 3rd day after infection, and the phagocytic capacity of corresponding macrophages increased significantly with the peak of CD36 expression on the 10th day after infection.
The protective immune response in the erythrocytic phase of malaria passes through the acute phase of infection and is eventually cleared of the parasite by a specific antibody-mediated immune response. The antibody-mediated regulatory phagocytosis may be one of the important mechanisms of the acquired immune response in the erythrocytic phase of malaria infection. FcR-mediated regulatory phagocytosis is the key to eliminating P.berghei XAT intraerythrocytic infection, suggesting that phagocytic activity of splenic macrophages is essential for host resistance to malaria infection. FcR gamma-/-(gamma chain knockout) mice are susceptible to P.berghei XAT due to lack of antibody-dependent phagocytosis and antibody-dependent cytotoxicity (ADCC). Mota et al. confirmed that the peripheral blood macrophages of CBA mice could exert antibody-mediated regulatory phagocytosis against P. chabaudi-chabaudi-infected erythrocytes and possess the specificity of the strain. Our previous study showed that DBA/2 mice had specific IgG against P. chabaudi-infected erythrocytes on the 10th day after the deadly P. yoelii infection. The expression of Fc gamma R I (CD64) on the surface of macrophages began to increase from the 5th day after infection, then gradually increased and maintained a high level. At the same time, the phagocytosis rate of macrophages was at a high level from the 8th to 15th day after infection. Macrophages may play a regulatory phagocytosis role through CD64.
In conclusion, this study systematically and dynamically observed the activation and effect of macrophages in resistant DBA/2 mice during natural infection of P.y 17XL, and further revealed that macrophages play an important role in both innate and acquired immunity against malaria infection. Further elucidation of the relevant mechanisms will provide necessary theoretical and experimental basis for the development of effective malaria vaccines and new antimalarial drugs.
conclusion
Macrophages play an important role in both innate and acquired immunity in the process of lethal Plasmodium yoelii infection.
The number of splenic macrophages in 1.DBA / 2 mice increased gradually.
2. the expression of MHC class II molecules indicated that macrophages were activated effectively under the stimulation of IFN- gamma.
3. The expression of scavenger receptor CD36 in macrophages increased significantly in the early stage of infection, which mediated the irrational phagocytosis.
4. Fc gamma RI (CD64), as a macrophage expression, increased significantly in the late stage of infection, which may be involved in antibody-mediated regulatory phagocytosis.
5. The level of NO secreted by macrophages increased significantly in the early stage of infection, thus inhibiting the outbreak of Plasmodium.
【学位授予单位】：中国医科大学
【学位级别】：硕士
【学位授予年份】：2007
【分类号】：R392
【参考文献】
相关期刊论文 前3条
1 曹雅明,王继春,刘英杰,阎建中,那立新;一氧化氮对红内期约氏疟原虫感染的影响[J];中国医科大学学报;2001年03期
2 郑伟;刘军;孟冬娅;胡晓芳;曹雅明;;致死型约氏疟原虫感染DBA/2小鼠保护性免疫机制的研究(英文)[J];中国寄生虫学与寄生虫病杂志;2006年01期
3 马世红;刘军;刘英杰;冯辉;吴忆;曹雅明;;抗疟治疗对宿主保护性免疫影响的实验研究[J];中国人兽共患病学报;2006年04期
本文编号：2212245
本文链接：https://www.wllwen.com/yixuelunwen/binglixuelunwen/2212245.html
最近更新
教材专著
