Discovery of 4-aminoquinoline therapeutics for visceral leishmaniasis

描述（由申请人提供）：该申请涉及广泛的挑战领域（15）转化科学和具体的挑战主题，15- ai -103：开发治疗被忽视的热带病的药物，特别强调疟疾。内脏利什曼病（VL）是一种由多诺瓦利什曼原虫引起的热带疾病，目前迫切需要新药来治疗。这项提议的重点是发现新的化合物，这些化合物将为VL患者带来新的治疗方法。本提案的具体目的是通过优化4-氨基喹啉先导化合物来确定内脏利什曼病的新候选药物。以感染多诺瓦杆菌的仓鼠为实验对象，建立了一种新的离体脾外植体模型，用于鉴定具有抗利什曼原虫活性的4-氨基喹啉衍生物。我们实验室最近开发的这种新模型，利用了仓鼠和人类VL之间的致病相似性，并提供了独特的机会，在导致疾病进展的致病机制的背景下，发现对寄生虫有活性的化合物。我们建议通过化学优化我们之前确定的4-氨基喹啉先导化合物来确定治疗VL的候选药物。我们将通过一个系统的、平行的和重复的过程来重复循环合成小的（40- 80个化合物）4-氨基喹啉衍生物的迭代文库，筛选文库的抗利什曼活性、毒性和药物相似性，并重复SAR分析以产生新的化合物进行测试。喹啉分子有几个显著的特点，有利于药物开发，与结构-活性关系（SAR）相关的大量数据的可用性，以及先前成功开发用于疟疾的喹啉类药物将极大地促进所提出的研究。所提出的方法是可行的，因为新化合物的合成和测试速度很快。用于化合物毒性、吸收和稳定性/代谢的体外测定是该领域的标准。离体脾外体模型是一种创新的方法，因为4-氨基喹啉衍生物的抗利什曼原虫活性将被测试(1)在中高通量格式中，(2)在脾脏的细胞微环境中，其中包括发挥免疫病理作用的细胞，已知会深刻影响寄生虫的复制或杀死，(3)对抗细胞内无性鞭毛虫（哺乳动物阶段），而不是无性培养的原生鞭毛虫（载体阶段），它们对抗利什曼原虫化合物表现出不一致的反应，(4)对脾巨噬细胞中的无尾线虫，其功能与传统使用的腹膜巨噬细胞不同，(5)将被确定为具有抗利什曼原虫活性，无论是通过直接杀死寄生虫和/或间接免疫介导机制。此外，Frantz博士实验室的化学优化和SAR分析与Melby博士实验室的生物测试相结合，将能够有效地发现新的化合物，适合未来在临床前仓鼠模型中进行进行性VL的体内功效测试。

DESCRIPTION (provided by applicant): This application addresses broad Challenge Area (15) Translational Science and specific Challenge Topic, 15-AI-103: Develop drugs for neglected tropical diseases, with a special emphasis on malaria. New drugs are desperately needed to treat visceral leishmaniasis (VL), a tropical disease cause by the protozoan Leishmania donovani. This proposal is focused on the discovery of new compounds that will feed into the pipeline bringing new therapeutics to patients with VL. The Specific Aim of this proposal is to identify novel drug candidates for visceral leishmaniasis through optimization of 4-aminoquinoline lead compounds. A novel ex vivo splenic explant model, derived from hamsters infected with L. donovani, will be used to identify new 4-aminoquinoline derivatives with anti-leishmanial activity. This new model, which was recently developed in our lab, capitalizes on the pathogenic similarities between hamster and human VL and offers the unique opportunity to discover compounds that are active against the parasite within the context of the pathogenic mechanisms that contribute to progressive disease. We propose to identify candidate drugs for the treatment of VL by chemical optimization of the 4-aminoquinoline lead compounds we previously identified. We will do this through a systematic, parallel, and iterative process of repeated cycles of synthesis of small (40- 80 compound) iterative libraries of 4-aminoquinoline derivatives, screening of the libraries for anti-leishmanial activity, toxicity, and drug-likeness, and repeated SAR analysis to generate new compounds for testing. Quinoline molecules have several notable characteristics that favor drug development and the availability of extensive data related to structure-activity relationship (SAR) and the prior successful development of quinolines for malaria will greatly facilitate the proposed studies. The proposed approach is feasible because of the rapidity with which new compounds will be synthesized and tested. The in vitro assays to be used for compound toxicity and absorption and stability/metabolism are standard for the field. The ex vivo splenic explant model is an innovative approach because the anti-leishmanial activity of 4-aminoquinoline derivatives will be tested (1) in a medium- to high-throughput format, (2) within the cellular microenvironment of the spleen, which includes the cells that exert immunopathologic effects known to profoundly influence parasite replication or killing, (3) against intracellular amastigotes (mammalian stage) rather than axenically cultured promastigotes (vector stage), which show discordant responses to antileishmanial compounds, (4) against amastigotes in splenic macrophages, which are functionally distinct from the traditionally used peritoneal macrophages, and (5) will be identified as having anti-leishmanial activity whether it is through direct parasite killing and/or indirect immune-mediated mechanisms. Furthermore, the integration of the chemical optimization and SAR analysis by Dr. Frantz's laboratory with the biological testing by Dr. Melby's laboratory will enable the efficient discovery of new compounds suitable for future in vivo efficacy testing in the pre-clinical hamster model of progressive VL. PUBLIC HEALTH RELEVANCE: Visceral leishmaniasis (VL) is a major public health problem with millions of cases worldwide. This proposal is focused on the discovery of new compounds that will feed into the pipeline bringing new therapeutics to patients with VL.