寄生虫感染与免疫1.ppt

吸虫结构 绦虫（Tapeworm） 线虫（Nematode） 医学节肢动物（Medical arthropod） 马来布鲁线虫能够编码哺乳动物细胞因子 TGF-β的同源物Bm-TGH-1 和Bm-TGH-2, 后者在体外由成虫所分泌并能和宿主的TGF-β受体相结合；也能表达在功能和结构上与宿主MIF（macrophage migration inhibitory factor) 极相似的蛋白, 尽管二者只有28%的同源性。 Example 1 Maizels RM , Gomez- Escobar N, Gregory WF, et al. Immun evasion genes f rom f ilarial nematodes[ J ] . Int J Parasitol, 2001,31( 9) : 889- 898. Example 2 Schistosoma mansoni Excretory Circulating Cathodic Antigen Shares Lewisx Epitopes With a Human Granulocyte Surface Antigen and Evokes Host Antibodies Mediating Complement-Dependent Lysis of Granulocytes 华支睾吸虫LysoPLA氨基酸序列比对，与人的LysoPLA1同源性为47% 较高浓度的溶血磷脂可破坏生物膜的构象，甚至引起细胞死亡。溶血磷脂的降解主要通过溶血磷脂酶I (lysophospholipase I, LysoPLA I）。 Example 3 （３）表膜脱落与更新 　虫体表膜脱落与更新，与表膜结合的抗体随之脱落。 如： S.mansoni成虫在有特异抗体存在时能脱去部分表 皮，然后再修复； S.mansoni尾蚴钻入皮肤时脱去其体表的糖萼，皮肤 中的童虫也能脱去表面抗原而保持完整形态。 肝片吸虫幼虫膜外层可不断被剥脱并再生。 ３、抑制宿主的免疫应答 （1）细胞因子的免疫调节 通过主动调整Th1细胞因子与Th2细胞因子的平衡，使寄生虫逃避宿主对其进行免疫杀伤，同时又不使宿主产生严重的免疫抑制，使其在宿主体内长期寄生。 Major components of the granulomatous response to schistosome eggs in the host liver and the main cytokines and chemokines that regulate this response. Legend: Egg, Neutrophil, Eosinophil, Macrophage, Hepatic Stellate Cell，Fibroblast, Collagen Fibres, CD4+T-cell/B-cells, Hepatocytes. 日本血吸虫虫卵肉芽肿及其纤维化 Possible involvement of immune cells and mediators in the helminth-induced immunomodulation on T helper subsets. Substances contained in the bodies of helminths or their excretory secretory (ES) products are recognized by innate immune cells via PAMPs receptors like TLRs. Thereafter, various changes occur in the immune cells, for example, down-modulation of IL-12/23p40 expression (DC), alternative activation (macrophages), proliferation and/or IL-10 production (Treg, Tr1, and B cells), and IL-4 production (basophils). We can observe suppression of immune disorders with down-regulation of pathogenic T helper subsets (Th1, Th17, and allergic Th2) as consequence of mixed effects of such immunological changes. （2）激活Treg细胞 如:感染血吸