Role of African Trypanosome Extracellular Vesicles in Infection and Pathogenesis

寄生虫之间的细胞间通讯以及与宿主细胞的通讯为寄生虫提供了机制 发育、免疫逃避和疾病病理学。血流非洲锥虫产生 起源于鞭毛膜并解离为游离的膜状纳米管(NTS) 细胞外小泡(EVS)。锥虫EV含有几种鞭毛蛋白，它们有助于 哺乳动物寄主的毒力包括钙鞭毛蛋白、腺苷环化酶(GRESAG4)、 糖基磷脂酰肌醇磷脂酶C(GPI-PLC)、钙网蛋白和基质天冬氨酸酶4。此外， 人类昏睡病寄生虫布氏锥虫产生的电动汽车含有 血清抗性相关蛋白(SRA)是人类传染性所必需的毒力因子.我们 已经表明，罗氏锥虫EV将SRA转移到非人类感染性锥虫体内，从而使 逃避人类的先天免疫力。形态和生物物理研究表明， 锥虫EVS还可以与磷脂酰胆碱脂质体、锥虫鞭毛袋 和哺乳动物的红细胞。锥虫EV与红细胞的融合改变了物理性质 红细胞膜硬度增加，导致红细胞迅速清除和贫血。这个 拟议的研究将扩展这些初步发现，并解决以下几个基本问题 膜NTS和EVS的功能。1)肠道病毒是在锥虫感染期间产生的吗？如果是 EV的产生率是多少？在感染过程中EV的货物是否会发生变化？2)EV是否 传递触发BF锥体分化的群体感应分子？3)NT/EV 途径提供了一种外排机制来清除人类昏睡病寄生虫的锥虫裂解物 因子(TLF)？4)EV是否递送锥虫效应器分子来调节锥虫细胞的产生 髓系细胞中的细胞因子肿瘤坏死因子-α？5)锥虫EV与宿主的融合 红细胞导致红细胞吞噬和贫血？6)哪些锥虫蛋白是必需的 用于电动汽车与膜的融合？总之，拟议的研究将使人们更好地了解 非洲锥虫EVS在细胞间通讯和致病机制中的作用 锥虫病。我们预计这些研究将导致开发新的诊断工具和 提供新的策略来对抗人类昏睡病和长假病中的贫血。

Intercellular communication between parasites and with host cells provides mechanisms for parasite development, immune evasion and disease pathology. Bloodstream African trypanosomes produce membranous nanotubes (NTs) that originate from the flagellar membrane and disassociate into free extracellular vesicles (EVs). Trypanosome EVs contain several flagellar proteins that contribute to virulence in the mammalian host including calflagin, adenylate cyclase (GRESAG4), glycosylphosphatidylinositol phospholipase C (GPI-PLC), calreticulin and metacaspase 4. In addition, the human sleeping sickness parasite Trypanosoma brucei rhodesiense produces EVs that contain the serum resistance associated protein (SRA) a virulence factor necessary for human infectivity. We have shown that T. b. rhodesiense EVs transfer SRA to non-human infectious trypanosomes allowing evasion of human innate immunity. Morphological and biophysical studies have shown that trypanosome EVs can also fuse with phosphatidylcholine liposomes, the trypanosome flagellar pocket and mammalian erythrocytes. Trypanosome EV fusion with erythrocytes alters the physical properties of erythrocytes increasing membrane rigidity resulting in rapid erythrocyte clearance and anemia. The proposed studies will extend these initial findings and address several fundamental questions about the function of membrane NTs and EVs. 1) Are EVs produced during trypanosome infection and if so what is the rate of production and does EV cargo change during the course of infection? 2) Do EVs deliver quorum-sensing molecules that trigger differentiation of BF trypanosomes? 3) Does the NT/EV pathway provide an efflux mechanism to rid human sleeping sickness parasites of trypanosome lytic factors (TLF)? 4) Do EVs deliver trypanosome effector molecules that modulate production of the cytokine, tumor necrosis factor-α, in myeloid cells? 5) Does the fusion of trypanosome EVs with host erythrocytes result in erythrophagocytosis and anemia? 6) What trypanosome proteins are necessary for EVs fusion to membranes? Together the proposed studies will result in a better understanding of the role of trypanosome EVs in cell-cell communication and pathogenesis associated by African trypanosomiasis. We anticipate these studies will lead to the development of new diagnostic tools and offer novel strategies to combat anemia in human sleeping sickness and Nagana.