Rational design of CNS-permeable cathepsin L inhibitors for treatment of chronic toxoplasmosis

项目总结 完全没有治疗慢性弓形虫(TG)感染的选择使~2 10亿人面临再次激活的弓形虫病风险。先天感染者或那些身体虚弱的人 免疫系统特别容易受到再次激活的弓形虫病的影响，表现为致命的脑炎， 心肌炎或失明。作为感染性后葡萄膜炎的主要原因和第二大原因 在美国，食源性死亡，重新激活的弓形虫病可以在高危人群中大幅减少 通过消除甘油三酯组织包囊来消除个体。我们使用新的遗传工具来确定一种 组织蛋白酶L在慢性甘油三酯感染过程中的活性，创造了一个令人兴奋的机会来开发 抗击再次激活的弓形虫病的新靶点。为了开始解决这一关键的未得到满足的需求，我们 根据其对中枢神经系统的穿透性和 对甘油三酯和人类组织蛋白酶L进行了初步的SAR研究，证明我们可以实现 在不到20个类似物中，TG酶的选择性提高了100倍以上。在R21阶段，我们将 使用基于结构的设计来进一步优化效力和选择性，同时提高稳定性和 在体外模型中的渗透性，提供一种或多种有效的、选择性的、稳定的和细胞渗透性的引线。在……里面 在R33阶段，我们将在测量之前评估和进一步细化小鼠的PK和CNS外显率 已建立的慢性甘油三酯感染小鼠治疗模型的最大耐受量和有效性。 这两个阶段都将以为研究开发的第一种囊性生存分析为特色。成功后 完成后，该项目将生产一种或多种甘油三酯CPL抑制剂，有效地减少或消除组织 包囊，从而为治疗慢性甘油三酯感染提供了一个潜在的新方案。 1

PROJECT SUMMARY The complete absence of treatment options for chronic Toxoplasma gondii (Tg) infection renders ~2 billion people at risk for reactivated toxoplasmosis. Congenitally infected individuals or those with weakened immune systems are particularly vulnerable to reactivated toxoplasmosis manifested as fatal encephalitis, myocarditis or loss of vision. As the leading cause of infectious posterior uveitis and second leading cause of foodborne deaths in the USA, reactivated toxoplasmosis could be substantially reduced in high-risk individuals by eliminating Tg tissue cysts. We used new genetic tools to identify an essential role for a cathepsin protease L (CPL) activity during chronic Tg infection, creating an exciting opportunity to exploit a new target for combatting reactivated toxoplasmosis. To begin addressing this key unmet need, we identified an initial lead dipeptide nitrile CPL inhibitor based on its potential for CNS penetrance and conducted primary SAR studies against Tg and human cathepsin L, demonstrating that we could achieve over 100-fold improvement in selectivity for the Tg enzyme in under 20 analogs. In the R21 phase we will use structure-based design to further optimize potency and selectivity along with improving stability and permeability in in vitro models, delivering one or more potent, selective, stable, and cell-permeable leads. In the R33 phase we will evaluate and further refine PK and CNS penetrance in mice before measuring maximum tolerated dose and efficacy in an established murine treatment model for chronic Tg infection. Both phases will feature first-of-their-kind assays for cyst viability developed for the studies. Upon successful completion, this project will yield one or more Tg CPL inhibitors effective for reducing or eliminating tissue cysts, thereby advancing a potential new solution for chronic Tg infection. 1