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

项目摘要 致病酵母白色念珠菌(Ca)是口腔和全身真菌感染的常见原因。 免疫功能受损的人和女性的阴道感染。念珠菌感染通常被治疗 对于唑类药物，这些患者群体中经常出现唑类耐药。少校 唑类耐药的机制包括外排泵表达增加和 麦角甾醇生物合成中的酶。然而，这些抗性机制尚未确定。 在许多耐药的临床分离株中。最近，发现了第三种唑类耐药性的机制 念珠菌生物膜-细胞和细胞外物质的基质，形成在粘膜表面和 植入的医疗器械。这些生物膜中高水平的唑类耐药性是由于增加了 在与唑类药物结合的细胞壁中产生？1，3葡聚糖。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种成分，也是浮游生物临床耐药的一种成分。 分离株。偶氮葡聚糖与细胞壁的结合会阻止药物到达细胞质， 阻力越来越大。总体目标是评估唑结合对β-1，3-葡聚糖的贡献。 作为念珠菌耐药性的一个组成部分。具体地说，这项提案调查了1，3-葡聚糖是如何 结合影响药物在真菌细胞中的积累，它评估了1，3葡聚糖结合 临床分离株，包括耐药机制未知的分离株。这样做的具体目的是 建议包括： 1.确定β-1，3-葡聚糖结合对氟康唑在念珠菌中积累的影响 白念珠菌。真菌细胞积累氮唑很可能是几个相互竞争的过程的结果， 包括输入和外流(内部积累)，以及可能的？？1，3葡聚糖结合(外部 积累)。放射性标记的FLC在细胞中的累积将在改变 细胞的葡聚糖含量。 2.检测药敏改变的临床分离株中β-1，3葡聚糖结合情况。偶氮 在耐药的临床中，将评估细胞中与？1，3葡聚糖的结合和？1，3葡聚糖水平 尚未确定其抗药性机制的菌株。 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。？？1，3葡聚糖与唑类药物的结合是其中一个新的重要方面。 互动。对这一过程的全面描述，以及我们对 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。叙述性 致病酵母菌白色念珠菌在口腔、阴道和 血液流动。这项建议将分析抗真菌药物氟康唑与 白色念珠菌。特别是，它将检验真菌细胞壁就像海绵一样，浸泡在 使药物上升，从而允许细胞在药物存在的情况下持续存在。

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.