Pharmacological Diversity of nAChRs in Clade III Nematodes: Levamisole receptors

描述（由申请人提供）：1。被忽视的热带病包括蛔虫病和淋巴丝虫病。这些疾病是由寄生线虫引起的，由于它们的分子相似性而被分组在进化枝III中。蛔虫病是由大肠蛔虫引起的。在全球范围内，它发生在14亿人身上。淋巴丝虫病（象皮病）威胁着83个国家的10亿多人;它是由马来丝虫等丝虫线虫引起的。控制这些线虫寄生虫（成虫或幼虫）依赖于数量有限的驱虫药物。有人担心大规模化疗会导致耐药性的发展。目前迫切需要进行研究，以便更好地利用现有药物，包括复方药物，以保护其价值，并开发新药。2.最近，一些新的线虫选择性胆碱能驱虫剂，如三苯双脒和derquantel（现在与阿维菌素协同），已被引入，并增加了胆碱能驱虫剂的意义。三苯双脒具有单剂量大规模给药的潜力。Derquantel对对其他胆碱能驱虫剂有抗药性的蠕虫有“破坏抗药性”的作用。线虫烟碱受体（nAChRs）的药理学比人们所认识的要复杂得多。在进化枝III型猪蛔虫（Ascaris suum）线虫中，肌肉nAChR分为N-、L-和B-亚型。分化体III肌肉受体（左旋咪唑受体）的药理学受受体亚基组成的调节。亚型和调制的治疗重要性需要进一步调查寄生线虫。我们有三个目标。3.我们的方法将使用肌肉收缩试验，电流钳，电压钳，膜片钳，克隆和爪蟾卵母细胞表达和药理学试剂，以表征胆碱能驱虫剂及其受体亚型的作用。目的#1将表征三苯双脒在A中的作用模式和亚型选择性。suum。它将检验三苯双脒对nAChR的L亚型没有选择性，但对A.并确定其作为开放通道阻滞剂的作用是否限制了疗效。目的#2将检查亚基排列和化学计量对蛔虫nAChR药理学的影响。它将表达A. suum在不同的组合中，以测试不同的亚基组合物再现天然肌肉受体（左旋咪唑受体）的药理学多样性的假设。目的#3将表征B中的nAChR应答和受体。malayi，以检验这些亚型与进化枝III线虫A. suum。4.该提案是创新的，探索未知的药物作用和亚基排列对进化枝III nAChRs药理学性质的影响。我们还扩展，马来丝虫寄生虫的准备，这组调查人员已经开发的方法。5.总体影响将是对以下方面的强大影响：三苯双脒（一种潜在的单剂量MDA）的扩展和知情使用;进化枝III线虫中烟碱驱虫剂靶位点的药理学多样性的扩展和知情使用;新型B的使用。用于研究离子通道靶点的马来制剂，供未来药物开发使用;开发或知情使用复方制剂（例如，derquantel与阿维菌素;或亚型选择性胆碱能驱虫剂的复方制剂）。

DESCRIPTION (provided by applicant): 1. The Neglected Tropical Diseases include ascariasis and lymphatic filariasis. These diseases are caused by parasitic nematodes that are grouped in Clade III because of their molecular similarities. Ascariasis is caused by the large intestinal roundworm, Ascaris lumbricoides. Worldwide, it occurs in 1.4 billion people. Lymphatic filariasis (elephantiasis) threatens over a billion people in 83 countries; it is caused by filaria nematodes like Brugia malayi. Control of these nematode parasites (adults or larvae) relies on a limited number of anthelmintic drugs. There are concerns that mass chemotherapy will lead to the development of resistance. There is a significant and urgent need for research that will allow better use of existing drugs, including combinations, to preserve their value, and to develop new drugs. 2. Recently, several novel nematode selective cholinergic anthelmintics, like tribendimidine and derquantel (now synergized with abamectin), have been introduced and increased the significance of cholinergic anthelmintics. Tribendimidine has potential for single-dose Mass Drug Administration. Derquantel has 'resistance busting' actions against worms that are resistant to other cholinergic anthelmintics. The pharmacology of nematode nicotinic receptors (nAChRs) is more complex than has been appreciated. The muscle nAChRs are divided into N-, L- and B-subtypes in the Clade III nematode Ascaris suum. The pharmacology of Clade III muscle receptors (levamisole receptors) are modulated by receptor subunit composition. The therapeutic importance of subtypes and modulation demands further investigation in parasitic nematodes. We have three aims. 3. Our approach will use muscle contraction assays, current-clamp, voltage-clamp, patch- clamp, cloning & Xenopus oocyte expression and pharmacological agents, to characterize actions of cholinergic anthelmintics and the subtypes of their receptors. Aim #1 will characterize the mode of action and subtype selectivity of tribendimidine in A. suum. It will test the hypothesis that tribendimidine is not selective for the L-subtype of nAChR but another type in A. suum and determine if its action as an open-channel blocker limits efficacy. Aim #2 will examine the effects of subunit arrangements and stoichiometry on pharmacology of Ascaris nAChRs. It will express four specific nicotinic receptor subunits from A. suum in different combinations to test the hypothesis that different subunit compositions reproduce the pharmacological diversity of native muscle receptors (levamisole receptors). Aim #3 will characterize nAChR responses and receptors in B. malayi, to test the hypothesis that the subtypes are functionally similar to the Clade III nematode, A. suum. 4. The proposal is innovative, exploring unknown drug effects and effects of subunit arrangements on the pharmacological properties of Clade III nAChRs. We also extend, to the Brugia malayi parasite preparation, the methods that this group of investigators has developed. 5. The overall impact will be a powerful influence on: expansion & informed use of tribendimidine, a potential single-dose MDA; the expansion and informed use of the pharmacological diversity of nicotinic anthelmintic target sites in Clade III nematodes; use of a novel B. malayi preparation for studying ion-channel targets for future drug development; development or informed use of combinations (e.g. derquantel with avermectins; or combinations of subtype selective cholinergic anthelmintics).