Identification of targets of the antiparasitic drug praziquantel

项目总结 这种寄生性感染血吸虫病困扰着全球2亿多人，临床治疗方法是使用 一种单一药物，吡喹酮(±PZQ)。尽管±PZQ几十年来一直是一种坚固的驱虫剂，但 这种药物的分子作用基础尚不清楚。这种机械论知识的缺乏阻碍了理性 替代疗法的设计，面对表现出血吸虫毒株的出现令人担忧 对±PZQ暴露的耐受性给予±PZQ对所有寄生生活史阶段无效。洞察 因此，需要±PZQ作用的靶点和它们的效应器来开发改进的驱虫疗法。 这个R01应用基于支持PZQ是5-羟色胺样配体这一前提的初步数据 在寄生虫和人类宿主中。我们实验室最近确定了R-PZQ和S的目标- PZQ是临床制剂±PZQ的两个对映体。R-PZQ是人5-HT2B G蛋白的配体 偶联受体(5-HT2B)，S-PZQ是人瞬时受体的5-羟色胺能调节剂 潜在的Melastatin 8离子通道(TRPM8)。这些发现意义重大，因为它们(I)为可能的 PZQ对映体在寄生虫中的靶点(5-羟色胺GPCRs和Trp通道)和(Ii)证明PZQ具有 不仅作为选择性的抗寄生剂，而且在寄主中也是活跃的。值得注意的是±PZQ急剧改变血管 成虫所在的肠系膜血管内的音调。5-羟色胺GPCRs的慢性参与 在肝脏中，星状细胞抑制由虫卵沉积引起的炎症反应引起的纤维化改变 宿主组织。将这种有益的寄主和有害的寄生活动结合起来，提供了一种新的途径 产生改进的抗寄生虫疗法，杀死蠕虫并防止它们造成的组织损伤。 根据我们的发现，我们将R-PZQ和S-PZQ分别定位在5-HT2BR和TRPM8上，并使用 这些结合姿势用于鉴定血吸虫生物胺能GPCRs中类似的结合结构(目标1)和 Trp通道(目标2)。根据这一策略，我们最近发现了一个血吸虫Trp通道，它是 受PZQ(10)调控--PZQ是迄今在扁虫中发现的第一个PZQ靶点。最后，我们将解决 驱虫剂寄主生物活性(目标3)对血管系统的急性影响的临床意义，以及 对肝星状细胞的慢性影响，启动纤维化改变，是许多病理基础的基础 慢性血吸虫病。我们的协作团队汇集了5-HT2B受体结构、Trp方面的专业知识 从分子(受体结构)到体内执行活动的通道生物学和血管生理学 病理学(调节寄生虫感染和肝病的机制)。如果成功，我们的活动将解决 ±PZQ的靶点和效应器，将使更好的驱虫疗法和辅助药物的开发成为可能。

PROJECT SUMMARY The parasitic infection schistosomiasis afflicts over 200 million people worldwide and is clinically treated using a single drug, praziquantel (±PZQ). Although ±PZQ has served as a stalwart anthelmintic for decades, the molecular basis of action of this drug remains undefined. This lack of mechanistic knowledge impedes rational design of alternative therapeutics and is worrisome in the face of emergence of schistosome strains exhibiting refractoriness to ±PZQ exposure given ±PZQ is ineffective against all parasitic life cycle stages. Insight into the targets of ±PZQ action, and their effectors, is therefore needed to develop improved anthelmintic therapies. This R01 application is based around preliminary data supporting a premise that PZQ is a serotonin-like ligand in both the parasite and the human host. Our laboratory has recently identified targets for both R-PZQ and S- PZQ, the two enantiomers in the clinical formulation of ±PZQ. R-PZQ is a ligand at the human 5-HT2B G protein coupled receptor (5-HT2B GPCR), and S-PZQ is a serotonergic regulator of the human transient receptor potential melastatin 8 ion channel (TRPM8). These findings are significant as they (i) provide clues to the likely targets of PZQ enantiomers in the parasite (5-HT GPCRs & TRP channels) and (ii) demonstrate that PZQ does not act as a selective antiparasitic, but also is active in the host. Notably ±PZQ acutely changes blood vessel tone within the mesenteric blood vessels where the adult worms reside. Chronic engagement of 5-HT GPCRs in hepatic stellate cells inhibited fibrotic changes caused by inflammatory reactions to worm eggs deposited in host tissues. Coalescing such beneficial host and deleterious parasitic activities provides a novel route to generating improved antiparasitic therapies that kill worms and prevent the tissue damage they cause. Based on our discoveries, we will map the binding sites of R-PZQ on 5-HT2BR, and S-PZQ on TRPM8 and use these binding poses to identify similar binding architectures in schistosome bioaminergic GPCRs (Aim 1) and TRP channels (Aim 2). Following this strategy, we have recently identified a schistosome TRP channel that is regulated by PZQ (10) – the first target of PZQ ever identified in a flatworm. Finally, we will address the clinical significance of host bioactivity of anthelmintics (Aim 3) in terms of acute effects on the vasculature, and chronic effects on hepatic stellate cells that initiate fibrogenic changes underpinning many of the pathologies of chronic schistosomiasis. Our collaborative team bring together expertise in 5-HT2B receptor structure, TRP channel biology and blood vessel physiology to execute activities from molecular (receptor structure) to in vivo pathology (mechanisms regulating parasite infection and liver disease). If successful, our activities will resolve targets and effectors for ±PZQ that will enable development of better anthelmintic therapies and adjuncts.