Preclinical Development of Novel Rickettsiosis Therapeutics Targeting EPAC1

描述（由申请人提供）：这是响应RFA-AI-13-013“生物防御合作伙伴关系（R 01）"的R 01申请。立克次氏体病是最具破坏性的人类传染病之一。这些蜱传疾病由立克次体属的专性胞内细菌引起，包括斑疹伤寒（普氏立克次体），一种NIAID类别B优先病原体。据预测，由于全球气候变化导致的气温升高将导致立克次体病的更广泛发病。此外，高传染性和 吸入立克次体后出现严重疾病，使其成为潜在的生物恐怖主义威胁。虽然立克次体感染如果早期诊断可以通过适当的广谱抗生素治疗来控制，但高达20%的误诊或未治疗和5%的治疗落基山斑点热（RMSF）病例导致致命的结局。事实上，据报道，地中海斑疹热住院患者的死亡率高达32%。菌株R.在实验室中已经开发出对四环素和氯霉素具有抗性的普氏菌。因此，迫切需要新的基于机制的治疗方法。我们最近的研究表明，由cAMP直接激活的交换蛋白（Epac 1）在立克次体病中起重要作用。小鼠Epac 1基因缺失可保护其免受致命性立克次体病的侵害。最重要的是，我们开发了一流的小分子Epac特异性抑制剂（ESI）。使用这些ESI，我们进一步证明了Epac在体内的药理学抑制重现了Epac 1-null表型：用ESI治疗的野生型小鼠免受致命性立克次体病的影响。这些结果表明Epac 1是潜在致命性立克次体病的一个新的治疗靶点。在本提案中，我们将设计、合成和优化我们实验室中发现的主要候选药物，以发现和开发具有最小毒性、所需药代动力学（PK）和药效学（PD）特性的更有效和特异性的ESI。将进一步分析优化的ESI用于临床前试验的有效性和安全性，以在体内动物模型中鉴定候选药物，用于开发立克次体病的有效治疗药物。

DESCRIPTION (provided by applicant): This is an R01 application in response to RFA-AI-13-013 "Partnerships for Biodefense (R01)". Rickettsioses represent some of the most devastating human infections. These tick-borne diseases are caused by obligately intracellular bacteria of the genus Rickettsia, including typhus fever (Rickettsia prowazekii), an NIAID Category B Priority pathogen. It has been forecasted that temperature increases due to global climate change will lead to more widespread incidence of rickettsioses. In addition, a high infectivity and severe illness after inhalation make rickettsiae potential bioterrorism threats. Although rickettsil infections can be controlled by appropriate broad-spectrum antibiotic therapy if diagnosed early, up to 20% of misdiagnosed or untreated and 5% of treated Rocky Mountain spotted fever (RMSF) cases result in a fatal outcome. In fact, a fatality rate as high as 32% has been reported in hospitalized patients with Mediterranean spotted fever. Strains of R. prowazekii resistant to tetracycline and chloramphenicol have been developed in laboratories. Therefore, novel mechanism-based treatments are urgently needed. Our recent studies reveal that exchange protein directly activated by cAMP (Epac1) plays an important role in rickettsiosis. Deletion of Epac1 gene in mice protects them from fatal rickettsioses. Most importantly, we have developed first-in-class, small-molecule Epac specific-inhibitors (ESIs). Using these ESIs, we have further demonstrated that pharmacological inhibition of Epac in vivo recapitulates the Epac1-null phenotype: wild-type mice treated with an ESI are protected from fatal rickettsioses. These results indicate that Epac1 is a novel therapeutic target for potentially fatal rickettsiosis. In te present proposal, we will design, synthesize and optimize the lead candidates discovered in our laboratory for the discovery and development of more potent and specific ESIs with minimal toxicity, desired pharmacokinetic (PK) and pharmacodynamic (PD) properties. Optimized ESIs will be further analyzed for preclinical testing for efficacy and safety to identify drug candidate in animal models in vivo for the development of effective therapeutics for rickettsioses.