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

项目摘要 致病性酵母菌白色念珠菌（Ca）是口腔和全身真菌感染的常见原因， 免疫力低下的人群和女性阴道感染的风险。念珠菌感染通常是治疗 唑类药物，唑类药物耐药性经常出现在这些患者群体。主要 唑类耐药的机制包括外排泵表达的增加和 麦角甾醇生物合成中的酶。然而，这些耐药机制尚未确定 在许多耐药的临床分离株中。最近，第三种唑类耐药机制被发现， 念珠菌生物膜-在粘膜表面形成的细胞和细胞外物质的基质， 植入式医疗器械这些生物膜中的高水平的唑类耐药性是由于增加的 生产？细胞壁中的1，3-葡聚糖与唑类药物结合。我们的假设是：？1，3-葡聚糖 唑类化合物的结合不仅是生物膜耐药的一个组成部分， 分离株唑类与细胞壁的葡聚糖结合将阻止药物到达细胞质， 增加阻力。总体目标是评价唑类化合物结合对？？1，3-葡聚糖 作为念珠菌耐药性的组成部分。具体来说，这项建议调查如何？？1，3-葡聚糖 结合影响真菌细胞中的药物积累，并评估？1，3-葡聚糖结合在一系列 临床分离株，包括无已知耐药机制的分离株。具体目标是 建议如下： 1.为了确定？？1，3-葡聚糖结合对氟康唑在念珠菌中蓄积的影响 白色念珠菌真菌细胞积累唑可能是几个竞争过程的结果， 包括进口和外排（内部积累），以及可能？？1，3-葡聚糖结合（外部 积累）。将在改变细胞中放射性标记的FLC蓄积的条件下评价细胞中放射性标记的FLC蓄积。 细胞的葡聚糖含量。 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。唑 绑定到？？1，3葡聚糖，和？将在耐药临床试验中评估细胞中的1，3葡聚糖水平。 分离株，其中没有已知的耐药机制已被确定。 唑类和真菌细胞之间的相互作用将继续是临床上重要的问题， 可预见的未来??唑类药物的1，3-葡聚糖结合是这些药物的一个新的和重要的方面。 交互.对这一进程的全面描述，以及我们对这一进程其他方面的理解， 药物/细胞相互作用，有可能有助于改善诊断，治疗和 预防真菌感染和耐药性。叙事 致病酵母菌白色念珠菌会导致口腔、阴道和其他严重的人类疾病。 血流本提案将分析抗真菌药物氟康唑与 C.白色念珠菌特别是，它将测试真菌细胞壁作为海绵的假设， 增加药物，从而使细胞在药物存在下持续存在。

Project Summary 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 proposal 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. Narrative 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.