Latrunculin B as a new drug lead for the treatment of Acanthamoeba keratitis

项目总结 棘阿米巴角膜炎(AK)可以发生在健康的戴隐形眼镜的人身上，这是一种痛苦的致盲 由自由生活的阿米巴棘阿米巴引起的角膜感染。并发症包括慢性眼球 炎症、角膜融化和疤痕形成。目前对AK的治疗依赖于洗必泰的联合治疗， 异硫代丙烷胺和聚六亚甲基双氰酸酯。然而，在10%的病例中，反复感染 由于很难杀死滋养体和双壁包囊，因此也会出现这种情况。因此，发展 有效和安全的药物是避免失明的一个关键的未得到满足的需求。因为AK是一种罕见的疾病，所以有一种 制药业的药物发现工作很少，主要是针对这种感染的药物发现 依靠学术研究中心。减少与开发相关的成本、时间和风险 新的AK疗法，我们专注于开发外用乳链菌素B，完成I/II期安全性， AK治疗高眼压和青光眼患者的耐受性和疗效研究 海洋天然产物Latrunculin B，其靶向于滋养体的肌动蛋白细胞骨架，并发现 在阿米巴德的表型筛选中，奠定了这一提议的基础。与这项提案相关的数据显示， (1)马兜铃素B对三种临床菌株卡氏不动杆菌有阿米巴杀灭作用，(2)低剂量的短期治疗 牛膝菌素B的浓度导致肌动蛋白细丝解聚，随后解体。 以及(3)一种新的基于图像的杀囊方法。 可用于研究赤霉素B的杀囊效果。基于这些数据，我们建议1)试验 对多种基因型棘阿米巴滋养体和包囊的抑制作用，2)耐受性 和药代动力学-药效学研究，以及3)试验 外用链球菌素B对两种不同棘阿米巴所致AK动物模型的体内疗效 基因分型。这项研究是获得局部给药的孤儿药物指定的必要步骤。 牛膝菌素B用于治疗AK。鉴于棘阿米巴有效药物靶点的不足，这项研究 还将促进AK新的靶向治疗方案的开发。在这项工作中取得的成果 可以推广到其他自由生活的阿米巴。为了成功实现提案目标，我们依靠我们的 合作结合了Debnath博士(Pi)在棘阿米巴寄生虫生物学方面的独特专业知识和Dr。 阿夫沙里眼科(联合调查员)。Debnath博士和AfShari博士的专业知识和经验具有潜力 将我们的药物发现平台提升到翻译的水平。

PROJECT SUMMARY Acanthamoeba keratitis (AK) can occur in healthy individuals wearing contact lenses and it is a painful blinding infection of the cornea caused by a free-living ameba Acanthamoeba. Complications include chronic ocular inflammation, corneal melting and scarring. Current treatment for AK relies on a combination of chlorhexidine, propamidine isethionate, and polyhexamethylene biguanide. However, in 10% of cases recurrent infection ensues, because of the difficulty in killing both trophozoites and double-walled cysts. Therefore, development of efficient and safe drugs is a critical unmet need to avert blindness. Because AK is a rare disease, there is a paucity of drug discovery efforts by the pharmaceutical industry and drug discovery for this infection largely relies on academic research centers. To reduce the cost, time and risk associated with the development of new AK therapies, we focused on the development of topical latrunculin B that completed Phase I/II safety, tolerability and efficacy study in patients with ocular hypertension and glaucoma for the treatment of AK. Marine natural product latrunculin B, which targets actin cytoskeleton of A. castellanii trophozoites and found amebicidal in a phenotypic screen, laid the foundation for this proposal. Data related to this proposal show that (1) latrunculin B is amebicidal against three clinical strains of A. castellanii, (2) a short treatment with low concentration of latrunculin B led to depolymerization of actin filaments and subsequent disorganization of acanthopodia in A. castellanii trophozoites, and (3) a novel image-based cysticidal assay developed by the PI could be used to investigate the cysticidal effect of latrunculin B. Based on these data, we propose to 1) test latrunculin B, against trophozoites and cysts of multiple genotypes of Acanthamoeba, 2) conduct tolerability and pharmacokinetic-pharmacodynamic studies of topically administered latrunculin B for AK, and 3) test in vivo efficacy of topical latrunculin B in an animal model of AK caused by Acanthamoeba of two different genotypes. This study is a necessary step toward obtaining orphan drug designation of topically administered latrunculin B for the treatment of AK. Given a deficit of the validated drug targets in Acanthamoeba, this study will also enhance the development of novel targeted treatment option for AK. The results obtained in this work may be expanded to other free-living amebae. To successfully achieve the proposal goals, we rely on our collaboration that combines the unique expertise of Dr. Debnath (PI) in Acanthamoeba parasite biology and Dr. Afshari in ophthalmology (Co-Investigator). Drs. Debnath and Afshari’s expertise and experience has potential to elevate our drug discovery platform to a translational level.