The molecular pathogenesis of hookworm anemia

描述：(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， 肠道线虫是缺铁性贫血的主要原因 在世界上。钩虫性贫血的发病机制是由 成虫附着在肠粘膜上时引起的出血。 虽然近一个世纪以来，人们一直欣赏成虫产生的 血栓形成的有效抑制剂，直到最近才有分子机制 寄生虫的血液摄食过程已经被阐明。强有力的 凝血和血小板功能的抑制物已被确定为可溶性的 人钩虫寄生虫的蛋白质提取物和分泌产物 塞兰钩口线虫。抗凝血剂已从成虫A. Cylanicum RNA，该重组蛋白可抑制Cylanicum RNA的活性。 凝血因子Xa通过一种新的机制。血小板抑制物可阻断 两种重要的血小板整合素--糖蛋白Jib/Lila的功能 (GPIIb/IIIa)和GPIa/IIa，它们介导血小板与纤维蛋白原和 分别为胶原蛋白。我们假设这些抗血栓药物在 活血在钩虫性贫血发病机制中的核心作用 进食并加重胃肠道出血。作用机制 钩虫Xa因子抑制剂的体外特性将使用 凝血因子Xa结合、蛋白酶介导的抑制物裂解和结合位点的研究 定向诱变。该血小板抑制物将从 并对其作用机制进行了体外实验研究。 GPIa/IIa和GPIJb/IIIA整合素结合的检测。使用可繁殖的动物 头孢曲霉感染模型及抗凝剂和血小板的作用 钩虫贫血发病机制中的抑制剂将使用一种 以疫苗为基础的方法。动物将用每个重组疫苗进行免疫 抑制剂，然后用50只感染性L3钩虫幼虫攻击。这个 将通过酶联免疫吸附试验监测对免疫的反应，以及免疫接种的程度 以抗血栓药物为靶点的抗体可保护小鼠 钩虫性贫血和体重减轻将使用临床参数和 蠕虫负荷测量。这些研究将最终确定 吸血在钩虫病发病机制中的作用以及鉴定 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.