Novel Antifungal Therapeutic Approaches

描述(申请人提供)：由于艾滋病、移植、化疗、类固醇和抗生素，以及侵入性程序和医疗设备，真菌感染正在增加。抗真菌药物仅限于两性霉素B、氟胞嘧啶和氮唑类药物，但现在蜡烛类、第二代氮唑类和脂类两性霉素制剂扩大了抗真菌药物的应用范围。然而，由于难以提供非肠外药物，疗效一致，需要快速、短疗程的治疗，以及新出现的耐药性，治疗进展仍有待实现。我们的研究集中在信号级联信号作为抗真菌药物的靶点。建议对白色念珠菌和新生隐球菌进行研究，白色念珠菌是最常见的人类真菌病原体，在未能或没有接受HAART的艾滋病患者中仍然是主要的粘膜病原体，新生隐球菌是由于艾滋病流行而导致世界上真菌性脑膜炎的主要原因。 我们的研究确定了抗真菌免疫抑制剂环孢素A、FK506和雷帕霉素的作用机制和靶点。鉴定了钙调神经磷酸酶、亲环素、FKBP12和Tor1的真菌同源物，提供了对生物学作用的洞察和作为保守的药物靶点。确定了保留抗真菌活性的非免疫抑制类似物。证明了协同杀菌药物的相互作用，并阐明了作用机制。环孢菌素A或FK506对钙调神经磷酸酶的抑制作用与唑类抗白色念珠菌有很强的协同作用，在动物模型中也有治疗作用。最近的研究表明，钙调神经磷酸酶是一种Hsp90客户蛋白，而Hsp90突变或抑制剂也与唑类化合物有协同作用。 在这里，我们建议将Tor、钙调神经磷酸酶和FKBP12通路定义为治疗的靶点。首先，我们将表征Tor级联元件和功能，并以雷帕霉素和免疫抑制较少的雷帕霉素类似物(Rapalogs)为靶点。其次，我们将阐明Hsp90和钙调神经磷酸酶之间的关系，以及使唑类化合物具有杀菌作用的它们的抑制剂，并以新型Hsp90抑制剂、唑类化合物和钙调神经磷酸酶抑制剂为靶点。第三，我们将专注于FKBP12对已知抗真菌药物靶向的氨基生物合成级联的控制，并定义协同抗真菌药物组合。最后，药物、类似物和组合将在隐球菌病和念珠菌病的动物模型中进行测试。我们在天然产品、药物化学、酶学、结构生物学和动物模型方面的合作团队与我们在信号和靶标识别方面的专业知识相辅相成。其目标是利用信号级联反应来开发新的抗真菌疗法。

DESCRIPTION (provided by applicant): Fungal infections are increasing as a result of AIDS, transplantation, chemotherapy, steroids and antibiotics, and invasive procedures and medical devices. Antifungal agents were limited to amphotericin B, flucytosine, and azoles, but now the candins, second-generation azoles, and lipid based amphotericin formulations have expanded the antifungal drug armamentarium. Yet with difficulties in delivering parenteral agents, consistent efficacy, need for rapid, short courses of therapy, and emerging drug resistance, therapeutic advances remain to be achieved. Our research focuses on signaling cascades as targets for antifungal drugs. Studies are proposed on Candida albicans, the most common human fungal pathogen that remains a major mucosal pathogen in AIDS patients who fail or do not receive HAART, and Cryptococcus neoformans, the leading cause of fungal meningitis in the world due to the AIDS epidemic. Our studies have defined the mechanisms of action and targets for the antifungal immunosuppressants cyclosporin A, FK506, and rapamycin. Fungal homologs of calcineurin, cyclophilin, FKBP12, and Tor1 were identified, providing insight into biological roles and as conserved drug targets. Nonimmunosuppressive analogs that retain antifungal activity were identified. Synergistic fungicidal drug interactions were demonstrated and mechanisms of action elucidated. Calcineurin inhibition by cyclosporin A or FK506 is potently synergistic with azoles against C. albicans and of therapeutic benefit in animal models. Recent studies implicate calcineurin as an Hsp90 client protein, and Hsp90 mutations or inhibitors are also synergistic with azoles. Here we propose to define Tor, calcineurin, and FKBP12 pathways as targets for therapy. First, we will characterize Tor cascade elements and functions and target this pathway with rapamycin and less immunosuppressive rapamycin analogs (rapalogs). Second, we will elucidate relationships between Hsp90 and calcineurin and their inhibitors that render azoles fungicidal and target this pathway with novel Hsp90 inhibitors, azoles, and calcineurin inhibitors. Third, we will focus on FKBP12 control of an amino biosynthetic cascade targeted by known antifungal agents and define synergistic antifungal drug combinations. Finally, drugs, analogs, and combinations will be tested in animal models of cryptococcosis and candidiasis. Our assembled team of collaborators in natural products, medicinal chemistry, enzymology, structural biology, and animal models complements our expertise in signaling and target identification. The goal is to harness signaling cascades to develop novel antifungal therapies.