The Molecular Pathogenesis of Hookworm Anemia

描述（由申请人提供）：超过10亿人在 发展中国家目前感染了吸血钩虫， 肠道线虫是导致缺铁性贫血的主要原因 世界上钩虫贫血的发病机制是一个直接的结果， 成虫附着在肠粘膜上引起的出血。 虽然近世纪来人们都认为成年钩虫 血栓形成的有效抑制剂，直到最近才有分子机制， 寄生虫吸血过程的基本原理已被阐明。强效 已经在可溶性血小板中鉴定出凝血和血小板功能的抑制剂， 人钩虫寄生虫的蛋白质提取物和分泌产物 锡兰钩虫抗凝血剂已从A. 该重组蛋白质抑制了锡兰真菌RNA的活性， 凝血因子Xa通过潜在的新机制。血小板抑制剂 似乎通过阻断两种重要的血小板整联蛋白的功能起作用， 介导血小板结合的糖蛋白IIb/IIIa（GPHb/IIIa）和GPIa/IIa 纤维蛋白原和胶原蛋白。我们假设这些 抗血栓药物在钩虫性贫血的发病机制中起着重要作用， 促进血液供应并加重胃肠道出血。的 钩虫因子Xa抑制剂的作用机制将被表征 使用Xa因子结合的体外研究，蛋白酶介导的抑制剂 切割和定点诱变。血小板抑制剂将是 从A.锡兰，其作用机制将是 使用GPIa/IIa和GPIIb/IIIa整联蛋白的体外测定表征 约束力采用可重复的A.锡兰虫感染，作用 抗凝血剂和血小板抑制剂在钩虫发病中的作用 贫血将使用基于疫苗的方法来表征。动物将 用每种重组抑制剂免疫，然后用50 传染性L3钩虫幼虫。ELISA，以及抗体 抗血栓药物的研究。锡兰防钩虫 贫血和体重减轻将使用临床参数和蠕虫进行评估。 负担计量将监测免疫接种反应。这些研究 将最终决定血液喂养在发病机制中的作用， 钩虫病，以及确定人类疫苗潜在靶点 对抗这种全球重要的寄生虫

DESCRIPTION (provided by the applicant): More than one billion people in developing countries are currently infected with blood feeding hookworms, intestinal nematodes that represent a leading cause of iron deficiency anemia in the world. The pathogenesis of hookworm anemia is a direct result of hemorrhage caused by the adult worm as it attaches to the intestinal mucosa. While it has been appreciated for nearly a century that adult hookworms produce potent inhibitors of thrombosis, only recently have the molecular mechanisms underlying the parasite blood feeding process been elucidated. Potent inhibitors of coagulation and platelet function have been identified in soluble protein extracts and secretory products of the human hookworm parasite Ancylostoma ceylanicum. The anticoagulant has been cloned from adult A. ceylanicum RNA, and the recombinant protein inhibits the activity of coagulation factor Xa by a potentially novel mechanism. The platelet inhibitor appears to act by blocking the function of two important platelet integrins, glycoprotein lib/Illa (GPHb/IIIa) and GPIa/IIa, which mediate platelet binding to fibrinogen and collagen, respectively. We hypothesize that these anti-thrombotics play a central role in the pathogenesis of hookworm anemia by facilitating blood feeding and exacerbating gastrointestinal hemorrhage. The mechanisms of action of the hookworm factor Xa inhibitor will be characterized using in vitro studies of factor Xa binding, protease mediated inhibitor cleavage, and site directed mutagenesis. The platelet inhibitor will be purified and cloned from A. ceylanicum, and its mechanism of action will be characterized using in vitro assays of GPIa/IIa and GPIIb/IIIa integrin binding. Using a reproducible animal model of A. ceylanicum infection, the role of the anticoagulant and platelet inhibitor in the pathogenesis of hookworm anemia will be characterized using a vaccine-based approach. Animals will be immunized with each recombinant inhibitor, followed by challenge with 50 infectious L3 hookworm larvae. ELISA, and the degree to which antibodies directed at the anti-thrombotics from A. ceylanicum protect against hookworm anemia and weight loss will be assessed using clinical parameters and worm burden measurements will monitor the responses to immunization. These studies will ultimately determine the role of blood feeding in the pathogenesis of hookworm disease, as well as identify potential targets for a human vaccine against this globally important parasite.