Parasite-specific proteasome inhibitors to combat multi-drug resistant malaria

项目摘要 恶性疟原虫的多重耐药形式直接导致了疟疾的巨大全球负担， 截至2015年，它影响了近2亿人，每年造成40多万人死亡。恶性疟原虫 对以前的一线药物氯喹和乙胺嘧啶-磺胺嘧啶的耐药性现在加剧了 对当前一线药物青蒿素（ART）和一些伙伴药物的耐药性的出现和蔓延 用于一线青蒿素（ART）为基础的联合疗法（ACT）。为了实现疟疾的既定目标， 消除，新的治疗策略是必不可少的，以消除多药耐药寄生虫。最近的研究 ART耐药寄生虫菌株的研究表明，它们可以通过上调 未折叠蛋白反应（UPR），这一过程依赖于多催化蛋白酶体的激活 复杂.因此，蛋白酶体抑制剂已显示与ART衍生物高度协同。 与ART不同，这些抑制剂也是活跃的肝脏、配子体和卵囊阶段。因此， 选择性靶向疟原虫蛋白酶体具有治疗的潜力，同时也阻断了 减少了从人到昆虫媒介的传播，并减少了抗药性的出现。我们假设 ART以及其他类别的当前抗疟疾药物和临床前候选药物， 恶性疟原虫中依赖于蛋白酶体活性以获得抗性的应激途径。我们也 假设蛋白酶体抑制剂具有广泛用于抑制 本地寄生虫种群的多药耐药性。这一建议是建立在强有力的初步结果之上的 使用底物筛选分析和我们最近解决的P. 恶性疟原虫20 S蛋白酶体设计具有纳摩尔效力的寄生虫蛋白酶体的选择性抑制剂 能有效清除体内啮齿类疟疾感染。我们发现蛋白酶体抑制剂显示出高度的 当与ART组合时具有协同作用，并且对ART抗性田间分离物有效。我们的初步 因此，结果确立了蛋白酶体是可行的抗疟疾药物靶点的范例。我们提出 开发改进的寄生虫特异性蛋白酶体抑制剂， 生物利用度，同时定义抑制剂可以最佳地 与抗疟疾药物协同作用，防止耐药性的传播。

Project Summary Multidrug-resistant forms of Plasmodium falciparum contribute directly to the massive global burden of malaria, which, as of 2015, impacts nearly 200 million people and result in over 400,000 deaths per year. P. falciparum resistance to the former first-line drugs chloroquine and pyrimethamine-sulfadoxine has now exacerbated the emergence and spread of resistance to the current first-line drug artemisinin (ART) and some partner drugs used in first line artemisinin (ART)-based combination therapies (ACTs). To achieve the stated goal of malaria elimination, new therapeutic strategies are essential to eliminate multi-drug resistant parasites. Recent studies of ART-resistant parasite strains suggest that they can resist drug-mediated killing by up-regulation of the unfolded protein response (UPR), a process that depends on activation of the multi-catalytic proteasome complex. Consequently, proteasome inhibitors have been shown to be highly synergistic with ART derivatives. Unlike ART, these inhibitors are also active liver, gametocyte and oocyst stages. Therefore, compounds that selectively target the Plasmodium proteasome have the potential to be curative while also blocking transmission from human to insect vector and reducing the emergence of drug resistance. We hypothesize that ART, as well as other classes of current anti-malarial drugs and preclinical candidates, induce stress pathways in P. falciparum that depend on proteasomal activity to achieve resistance. We also hypothesize that proteasome inhibitors have the potential to be broadly used to suppress the onset of multidrug resistance in native parasite populations. This proposal is built around strong preliminary results using substrate screening assays and our recently solved cryo-electron microscopy structure of the P. falciparum 20S proteasome to design selective inhibitors of the parasite proteasome with nanomolar potency that effectively clear rodent malaria infections in vivo. We find that proteasome inhibitors show a high degree of synergism when combined with ART and are potent against ART-resistant field isolates. Our preliminary results therefore establish the paradigm that the proteasome is a viable anti-malarial drug target. We propose developing improved parasite-specific proteasome inhibitors that have enhanced potency, selectivity and bioavailability while simultaneously defining the mechanism and conditions by which inhibitors can optimally synergize with anti-malarial agents to prevent the spread of resistance.