Exploring the potential to improve azole efficacy against Trypanosoma cruzi by targeting glutamine metabolism

项目总结 查加斯病寄生虫克氏锥虫的慢性感染是出了名的难以用 目前的药物治疗方案。克氏锥虫顽固性感染的机制(S)尚不清楚，但这一点仍然存在 这是该领域最紧迫的问题之一。在对药物失败的潜在解释中， 不同的代谢环境可能在克氏毛滴虫的药物敏感性中起作用，但尚未被探索。 最近，我们发现了谷氨酰胺代谢和一组 以克氏毛滴虫无鞭毛体中的甾醇生物合成为靶标的唑类化合物。我们发现在限制的条件下 谷氨酰胺利用率，细胞内无鞭毛体暴露于致命浓度的氮唑，包括 泊沙康唑，一种临床上未能清除慢性感染恰加斯患者的克氏毛滴虫感染的药物 审判。鉴于有证据表明谷氨酰胺水平在胃肠道区域最低，这些 已知寄生虫在唑类治疗后会持续和复发，我们的新发现可能具有重要的意义。 泊沙康唑未能清除小鼠和慢性查格斯病患者的寄生虫感染。这个 这个探索性的R21提案的目标是定义获得外源性谷氨酰胺的机制(S) 调节细胞内依赖于唑的杀灭克氏毛滴虫无鞭毛虫并鉴定小分子化合物 谷氨酰胺条件下特异性阻断寄生虫保护唑的分子文库筛选 文化上的限制。这项研究的结果有可能揭示谷氨酰胺敏感的辅助途径 在寄生虫中，可以靶向在低谷氨酰胺环境下增强氮唑的疗效，以及一组 化合物将成为未来功能研究的有力工具。

PROJECT SUMMARY Chronic infections with the Chagas disease parasite, Trypanosoma cruzi, are notoriously difficult to treat with the current drug regimens. The mechanism(s) underlying recalcitrant T. cruzi infection are unknown, but this remains one of the most pressing problems in the field. Of the potential explanations for drug failure, the role that heterogeneous metabolic environments might play in drug susceptibility in T. cruzi, has not been explored. Recently, we discovered a novel link between glutamine metabolism and the trypanocidal action of a group of azole compounds that target sterol biosynthesis in T. cruzi amastigotes. We find that under conditions of limiting glutamine availability, intracellular amastigotes survive exposure to lethal concentrations of azoles, including posaconazole, a drug that failed to clear T. cruzi infection from chronically-infected Chagas patients in clinical trials. Given evidence that glutamine levels are lowest in the region of the gastrointestinal tract that these parasites are known to persist and recrudesce following azole treatment, our novel findings may have important implications for the failure of posaconazole to clear parasite infection in mice and chronic Chagas patients. The goals of this exploratory R21 proposal are to define the mechanism(s) by which access to exogenous glutamine modulates azole-dependent killing of intracellular T. cruzi amastigotes and to identify compounds in small molecule library screens that specifically ablate parasite protection from azoles under conditions of glutamine restriction in culture. Results from this study have the potential to reveal auxiliary glutamine-sensitive pathways in the parasite that can be targeted to potentiate the efficacy of azoles in low glutamine settings as well a set of compounds that will serve as powerful tools for future functional studies.