Novel Antifungal Therapeutic Approaches

描述（由申请人提供）：由于艾滋病、移植、化疗、类固醇和抗生素以及侵入性手术和医疗器械，真菌感染正在增加。抗真菌药物仅限于阿替霉素B、氟胞嘧啶和唑类，但现在candins、第二代唑类和基于脂质的阿替霉素制剂扩大了抗真菌药物的范围。然而，由于难以递送胃肠外药剂、疗效一致、需要快速、短期疗程以及出现耐药性，治疗进展仍有待实现。我们的研究重点是信号级联作为抗真菌药物的目标。建议对白色念珠菌和新型隐球菌进行研究，白色念珠菌是最常见的人类真菌病原体，在接受HAART治疗失败或未接受HAART治疗的艾滋病患者中仍然是主要的粘膜病原体，新型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。 我们的研究已经确定了抗真菌免疫抑制剂环孢菌素A、FK506和雷帕霉素的作用机制和靶点。钙调神经磷酸酶，亲环素，FKBP12和Tor1的真菌同系物被鉴定，提供了对生物学作用的深入了解和作为保守的药物靶点。保留抗真菌活性的非免疫抑制类似物被鉴定。协同杀真菌药物相互作用得到证实，并阐明了作用机制。环孢菌素A或FK 506对钙调磷酸酶的抑制作用与唑类药物对C.白色念珠菌和动物模型中的治疗益处。最近的研究表明钙调磷酸酶是Hsp90的客户蛋白，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、钙调磷酸酶和FKBP 12通路定义为治疗靶点。首先，我们将表征Tor级联元件和功能，并使用雷帕霉素和免疫抑制性较小的雷帕霉素类似物（rapalogs）靶向该途径。其次，我们将阐明热休克蛋白90和钙调磷酸酶及其抑制剂，使唑类杀菌和靶向这一途径与新的热休克蛋白90抑制剂，唑类，钙调磷酸酶抑制剂之间的关系。第三，我们将重点关注FKBP 12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。我们在天然产物、药物化学、酶学、结构生物学和动物模型方面的合作者组成的团队补充了我们在信号传导和靶点识别方面的专业知识。我们的目标是利用信号级联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.