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通过一种新的机制。血小板抑制剂阻断了 两种重要的血小板整合素，糖蛋白Jib/lila的功能 （GPIIb/IIIa）和GPIa/IIa，其介导血小板与纤维蛋白原的结合， 胶原蛋白。我们假设这些抗血栓药物在 钩虫贫血的发病机制中的中心作用，通过促进血液 进食并加剧胃肠道出血。的作用机制 钩虫因子Xa抑制剂的特性将使用体外 因子Xa结合、蛋白酶介导的抑制剂切割和位点的研究 定向诱变血小板抑制剂将被纯化和克隆， A.锡兰，其作用机制将在体外进行表征 GPIa/IIa和GPIIb/IIIa整联蛋白结合的测定。使用可繁殖的动物 锡兰曲霉感染模型，抗凝剂和血小板的作用 钩虫性贫血发病机制中的抑制剂将使用 疫苗为基础的方法。将用每种重组体免疫动物 抑制剂，然后用50只感染性L3钩虫幼虫攻击。的 免疫应答将通过ELISA监测， 针对A.锡兰抗 钩虫贫血和体重减轻将使用临床参数进行评估， 蠕虫负载测量。这些研究将最终确定 血食在钩虫病的发病机制，以及确定 针对这种全球重要寄生虫的人类疫苗的潜在目标。

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 novel mechanism. The platelet inhibitor blocks the function of two important platelet integrins, glycoprotein Jib/lila (GPIIb/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 mechanism 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 GPIJb/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. The responses to immunization will be monitored by 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. 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.