Glucan Binding to Azole Drugs: A Novel Resistance Mechanism in Candida albicans

葡聚糖与唑类药物的结合：白色念珠菌的新型耐药机制

• 批准号: 7472204
• 负责人: Theodore C. White
• 金额: $ 27.22万
• 依托单位: SEATTLE BIOMEDICAL RESEARCH INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-03-01 至 2010-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7472204
• 关键词: Affect; Anabolism; Antifungal Agents; Area; Azole resistance; Azoles; Binding; Biochemical; Blood; Candida; Candida albicans; Catheters; Cell Communication; Cell Wall; Cells; Clinical; Collection; Condition; Cytoplasm; Dental Plaque; Dentures; Diagnosis; Drug resistance; Enzymes; Ergosterol; Exhibits; Extracellular Matrix; Fluconazole; Future; Genes; Glucans; Goals; Immune; Implant; Infection; Medical Device; Metabolism; Microbial Biofilms; Monitor; Monoclonal Antibodies; Mycoses; Oral; Oral cavity; Patients; Pharmaceutical Preparations; Population; Porifera; Predisposition; Preparation; Prevention; Process; Production; Public Health; Pump; Radiolabeled; Reporting; Research; Resistance; Resistance to infection; Standards of Weights and Measures; Sterol Biosynthesis Pathway; Sterols; Stream; Surface; Testing; Vagina; Woman; Yeasts; candida biofilm; cell preparation; clinically significant; drug testing; efflux pump; extracellular; human disease; novel; prevent; radiotracer; resistance mechanism

DESCRIPTION (provided by applicant): The pathogenic yeast Candida albicans (Ca) is a frequent cause of oral and systemic fungal infections in immune-compromised people and of vaginal infections in women. Candida infections are usually treated with azole drugs, and azole resistance arises frequently in these patient populations. The major mechanisms of azole resistance include increased expression of efflux pumps and alterations in enzymes in ergosterol biosynthesis. However, these mechanisms of resistance have not been identified in many resistant clinical isolates. Recently, a third mechanism of azole resistance has been found in Candida biofilms - matrices of cells and extracellular material that forms on mucosal surfaces and implanted medical devices. The high levels of azole resistance in these biofilms is due to increased production of (-1,3 glucan in the cell wall that binds to azole drugs. Our Hypothesis is that (-1,3 glucan binding of azoles is a component of resistance not only in biofilms, but in planktonic clinically resistant isolates. Glucan binding of azoles to the cell wall would prevent the drug from reaching the cytoplasm, increasing resistance. The Overall Goal is to evaluate the contribution of azole binding to (-1,3 glucan as a component of drug resistance in Candida. Specifically, this proposal investigates how (-1,3 glucan binding affects drug accumulation in fungal cells, and it evaluates (-1,3 glucan binding in a collection of clinical isolates, including isolates with no known resistance mechanisms. The Specific Aims of this application are: 1. To determine the effect of (-1,3 glucan binding on fluconazole accumulation in Candida albicans. Azole accumulation by fungal cells is likely to be the result of several competing processes, including import and efflux (internal accumulation), and possibly (-1,3 glucan binding (external accumulation). Radiolabeled FLC accumulation in cells will be evaluated under conditions that alter the glucan content of the cells. 2. To assess (-1,3 glucan binding in clinical isolates with altered drug susceptibilities. Azole binding to (-1,3 glucans, and (-1,3 glucan levels in the cells will be assessed in resistant clinical isolates in which no known mechanism of resistance has been identified. The interactions between azoles and fungal cells will continue to be clinically significant issues for the foreseeable future. (-1,3 glucan binding of azole drugs is a new and important aspect of these interactions. A full characterization of this process, together with our understanding of the other facets of drug/cell interactions, has the potential to contribute to improvements in diagnosis, treatment and prevention of fungal infections and of resistance. PUBLIC HEALTH RELEVANCE The pathogenic yeast Candida albicans causes significant human disease in the mouth, vagina and blood stream. This proposal will analyze the interaction between the antifungal drug fluconazole and C. albicans. In particular, it will test the hypothesis that the fungal cell wall acts as a sponge, soaking up the drug, thus allowing the cells to persist in the presence of drug.

描述（由申请人提供）：致病性酵母白色念珠菌（Ca）是免疫受损人群口腔和全身真菌感染以及女性阴道感染的常见原因。念珠菌感染通常用唑类药物治疗，这些患者群体中经常出现唑类药物耐药性。唑类耐药的主要机制包括外排泵表达增加和麦角甾醇生物合成酶的改变。然而，在许多耐药临床分离株中尚未发现这些耐药机制。最近，在念珠菌生物膜中发现了第三种唑类耐药机制——在粘膜表面和植入的医疗设备上形成的细胞和细胞外物质基质。这些生物膜中高水平的唑类耐药性是由于细胞壁中与唑类药物结合的 (-1,3 葡聚糖) 的产生增加。我们的假设是，(-1,3 葡聚糖与唑类的结合是耐药性的一个组成部分，而不是仅在生物膜中，但在浮游临床耐药分离株中，唑类与细胞壁的葡聚糖结合会阻止药物到达细胞质，从而增加耐药性。唑与(-1,3葡聚糖的结合作为念珠菌耐药性的一个组成部分。具体来说，该提案研究了(-1,3葡聚糖的结合如何影响真菌细胞中的药物积累，并评估了(-1,3葡聚糖在真菌细胞中的结合)收集临床分离株，包括没有已知耐药机制的分离株。本申请的具体目的是： 1. 确定 (-1,3 葡聚糖结合对白色念珠菌中氟康唑积累的影响。真菌细胞的唑积累可能是几个竞争过程的结果，包括输入和流出（内部积累），以及可能的（-1,3 葡聚糖结合（外部积累））。将在改变细胞葡聚糖含量的条件下评估细胞中放射性标记的 FLC 积累。 2. 评估药物敏感性改变的临床分离株中的 (-1,3 葡聚糖结合)。将在耐药临床分离株中评估细胞中与 (-1,3 葡聚糖和 (-1,3 葡聚糖) 结合的唑，其中没有已知的耐药机制已被确定，在可预见的将来，唑类药物与真菌细胞之间的相互作用将继续成为临床上的重要问题（唑类药物的-1,3葡聚糖结合是一个新的重要问题。对这一过程的全面表征，加上我们对药物/细胞相互作用其他方面的了解，有可能有助于改善真菌感染和耐药性的诊断、治疗和预防。致病性酵母白色念珠菌会在口腔、阴道和血液​​中引起严重的人类疾病。该提案将分析抗真菌药物氟康唑和白色念珠菌之间的相互作用，特别是检验该假设。真菌细胞壁充当海绵，吸收药物，从而使细胞能够在药物存在下持续存在。