Molecular characterization of a hookworm Macrophage Migration Inhibitory Factor

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。全世界有近10亿人感染了这些吸血线虫寄生虫，它们附着在肠粘膜上并摄取血液和组织。慢性钩虫病与严重贫血、营养不良和生长/认知延迟有关。钩虫附着在肠粘膜上存活多年，因此长期以来一直认为寄生虫必须有效地抑制宿主的免疫反应以延长存活时间。在人类和动物模型中均显示，钩虫感染与不同程度的免疫抑制相关，表现为对钩虫和异源抗原的淋巴细胞应答受损。然而，迄今为止，很少有人知道钩虫利用特定的进化策略，以逃避宿主组织迁移和随后的发展过程中，以建立或维持感染的宿主免疫反应。我们已经确定了一个同源的炎症性哺乳动物细胞因子巨噬细胞迁移抑制因子（MIF）从人类钩虫锡兰钩虫。这种新的蛋白质，AceMIF，存在于可溶性提取物和排泄/分泌（ES）蛋白从成年钩虫，但其在疾病发病机制中的潜在作用尚未确定。初步数据显示，AceMIF结合人MIF受体（CD 74），并具有与人MIF相似的巨噬细胞趋化性和互变异构酶催化活性。与人类蛋白质不同，AceMIF对哺乳动物MIFs的小分子抑制剂ISO-1具有抗性，为病原体特异性抑制剂的设计建立了概念证明。我们建议，AceMIF促进寄生虫的生存，有效地调节宿主的免疫反应，在该网站的附件内的主机小肠。将使用基于细胞的体外试验研究AceMIF的免疫调节作用，以阐明CD 74受体结合远端的信号转导事件。宿主MIF在体内表达的动力学将通过组织特异性ELISA推导，免疫组织化学研究将确定宿主和寄生虫MIF表达的空间关系。宿主MIF在钩虫感染过程中的作用将通过中和抗体和ISO-1的抑制作用进行研究。锡兰钩虫MIF在贫血和生长延迟发病机制中的作用将使用动物疫苗试验进行表征，旨在中和体内AceMIF的活性并损害蠕虫在肠道内存活的能力。这些研究将有助于开发旨在控制这一重要人类病原体的新方法。

DESCRIPTION (provided by applicant): Hookworm infection is the leading cause of malnutrition and anemia in the developing world. Nearly one billion individuals worldwide are infected with these bloodfeeding nematode parasites, which attach to the intestinal mucosa and ingest blood and tissue. Chronic hookworm disease is associated with severe anemia, malnutrition, and growth/cognitive delay. Hookworms survive for years attached to the intestinal mucosa, therefore it has long been theorized that the parasites must effectively dampen the host immune response in order to prolong survival. It has been shown both in humans and animal models that hookworm infection is associated with varying degrees of immunosuppression, manifested by impaired lymphocyte responses to both hookworm and heterologous antigens. However, to date, little is known about the specific evolutionary strategies utilized by hookworms to evade the host immune response during host tissue migration and subsequent development in order to establish or maintain an infection. We have identified an orthologue of the inflammatory mammalian cytokine macrophage migration inhibitory factor (MIF) from the human hookworm Ancylostoma ceylanicum. This novel protein, AceMIF, is present in soluble extracts and excretory/secretory (ES) proteins from adult hookworms, but its potential role in disease pathogenesis has not been defined. Preliminary data reveal that AceMIF binds the human MIF receptor (CD74), and possesses macrophage chemotaxis and tautomerase catalytic activity similar to that of human MIF. Unlike the human protein, AceMIF is resistant to the small molecule inhibitor of mammalian MIFs, ISO-1, establishing proof of concept for the design of pathogen specific inhibitors. We propose that AceMIF promotes parasite survival by effectively modulating the host immune response at the site of attachment within the host small intestine. The immunomodulatory role of AceMIF will be investigated using cell based in vitro assays to elucidate signal transduction events distal to CD74 receptor engagement. The kinetics of host MIF expression in vivo will be deduced through tissue-specific ELISA and immunohistochemical studies will define the spatial relationship of host and parasite MIF expression. The role of host MIF during hookworm infection will be investigated by inhibition with neutralizing antibodies and ISO-1 using a fully permissive animal model of A. ceylanicum. The role of hookworm MIF in the pathogenesis of anemia and growth delay will be characterized using animal vaccine trials aimed at neutralizing the activity of AceMIF in vivo and impairing the ability of adult worms to survive within the intestine. These studies will allow for the development of new methods aimed at controlling this important human pathogen.