The role of MIF in hookworm infection and disease

描述(由申请人提供)：钩虫感染是发展中国家营养不良和贫血的主要原因。超过10亿人感染了这些吸血线虫寄生虫，这些寄生虫附着在肠道粘膜上，以撕裂的毛细血管为食。钩虫可能会在肠道内存活数年，尽管存在宿主炎症反应。到目前为止，人们对成虫阻止先天性和获得性宿主免疫反应以求生存的机制知之甚少。最近从人钩虫中克隆了一个与哺乳动物细胞因子巨噬细胞迁移抑制因子(MIF)同源的EDNA。初步数据表明，重组头孢曲霉MIF(RAceMIF)具有酶活性，并与人蛋白竞争结合新近发现的MIF受体CD74。我们假设钩虫MIF同源物有效地调节宿主免疫反应，以促进寄生虫在粘膜表面的生存。本项目的目的是研究MIF在钩虫感染和疾病发病机制中的作用。AceMIF的作用机制将通过对MIF功能的体外研究来确定，包括互变构酶活性、巨噬细胞迁移和促炎细胞信号转导。将表征rAceMIF与CD74结合的动力学，并将利用X射线结晶学阐明其三维结构。AceMIF基因的体内表达特征将证明其阶段特异性，而AceMIF在成虫体内产生的来源将通过免疫组织化学来表征。平行研究将使用一个完全允许的头孢曲霉动物模型来分析宿主MIF在钩虫感染反应中的组织特异性表达。AceMIF在钩虫贫血和生长迟缓的发病机制中的作用也将通过疫苗和靶向基因沉默方法来表征。将通过ELISA监测对免疫的反应，并将使用临床参数和蠕虫负担测量来评估针对AceMIF的抗体对钩虫贫血和生长延迟的保护程度。这些研究将表征一种多功能人类细胞因子的新型蠕虫同源物，最终确定MIF在钩虫疾病发病机制中的作用。

DESCRIPTION (provided by the applicant): Hookworm infection is a leading cause of malnutrition and anemia in the developing world. More than one billion people are infected with these bloodfeeding nematode parasites, which attach to the intestinal mucosa and feed from lacerated capillaries. Hookworms may survive for years within the intestine, despite the presence of a host inflammatory response. To date, little is known about the mechanisms by which adult hookworms block components of the innate and acquired host immune responses in order to survive. A eDNA corresponding to a homologue of the mammalian cytokine Macrophage Migration Inhibitory Factor (MIF) has recently been cloned from the human hookworm Ancylostoma ceylanicum. Preliminary data suggest that the recombinant A. ceylanicum MIF (rAceMIF) is enzymatically active and competes with the human protein for binding to the recently identified MIF receptor CD74. We hypothesize that the hookworm MIF homologue effectively modulates the host immune response in order to facilitate parasite survival at the mucosal surface. The aim of this project is to characterize the role of MIF in the pathogenesis of hookworm infection and disease. The mechanism of action of AceMIF will be characterized using in vitro studies of MIF function, including tautomerase activity, macrophage migration, and pro-inflammatory cell signaling. The kinetics of rAceMIF binding to CD74 will be characterized, and its three dimensional structure will be elucidated using X-ray crystallography. AceMIF gene expression will be characterized in vivo in order to document its stage specificity, and the source of AceMIF production within the adult hookworm will be characterized by immunohistochemistry. Parallel studies will analyze tissue specific expression of host MIF in response to hookworm infection using a fully permissive animal model of A. ceylanicum. The role of AceMIF in the pathogenesis of hookworm anemia and growth delay will also be characterized using both vaccine and targeted gene silencing approaches. The response to immunization will be monitored by ELISA, and the degree to which antibodies directed at AceMIF protect against hookworm anemia and growth delay will be assessed using clinical parameters and worm burden measurements. These studies will characterize this novel helminth homologue of a multi functional human cytokine, ultimately determining the role of MIF in the pathogenesis of hookworm disease.