Preclinical Development of Novel Rickettsiosis Therapeutics Targeting EPAC1

描述(申请人提供)：这是一份R01申请，是对RFA-AI-13-013“生物防御伙伴关系(R01)”的回应。立克次体是一些最具破坏性的人类感染。这些壁虱传播的疾病是由立克次体属的细胞内细菌引起的，包括斑疹伤寒(普氏立克次体)，这是NIAID B类优先病原体。据预测，全球气候变化导致的气温上升将导致立克次体病更广泛的发病率。此外，高传染性和 吸入后的严重疾病使立克次体具有潜在的生物恐怖主义威胁。尽管如果及早诊断可以通过适当的广谱抗生素治疗来控制立克次体感染，但高达20%的误诊或未治疗以及5%的已治疗落基山斑点热(RMSF)病例会导致致命后果。事实上，据报道，地中海斑点热住院患者的病死率高达32%。已在实验室培育出对四环素和氯霉素具有抗药性的普罗瓦泽克乳杆菌菌株。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，cAMP直接激活的交换蛋白(Epac1)在立克次体病中起着重要作用。小鼠中Epac1基因的缺失可以保护它们免受致命立克次体病的侵袭。最重要的是，我们已经开发出一流的小分子EPAC特异性抑制剂(ESIS)。利用这些ESI，我们进一步证明了在体内对EPAC的药理抑制概括了Epac1缺失的表型：接受ESI治疗的野生型小鼠可免受致死性立克次体病的影响。这些结果表明，Epac1是一种治疗潜在致命立克次体病的新靶点。在目前的提案中，我们将设计、合成和优化我们实验室发现的候选先导药物，以发现和开发毒性最小、所需的药代动力学(PK)和药效学(PD)特性的更有效和更特异的ESIS。优化的ESIS将被进一步分析，用于临床前测试有效性和安全性，以在体内动物模型中确定候选药物，以开发有效的立克次体疗法。

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.