Fungal biofilm architecture produces hypoxic microenvironments that drive antifungal resistance
Fungal biofilm architecture produces hypoxic microenvironments that drive antifungal resistance
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DOI：
10.1073/pnas.2003700117
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发表时间：
2020-09-08
影响因子：
11.1
通讯作者：
Cramer, Robert A.
中科院分区：
文献类型：
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作者：
Kowalski, Caitlin H.;Morelli, Kaesi A.;Cramer, Robert A.
尽管在体外对真菌分离药物敏感，但人类真菌感染可能对体内当代抗真菌治疗无效。体外抗菌素敏感性和体内治疗结果之间的这种差异的部分原因是微生物在感染期间采用了耐药生物膜的生长模式。丝状真菌病原体烟曲霉在体内形成生物膜，在生物膜生长过程中，它降低了对所有三类当代抗真菌药物的敏感性。导致抗真菌耐药性的丝状真菌生物膜的具体特征在很大程度上仍不清楚。在这项研究中，我们应用荧光显微镜和转录生物记者相结合的方法来确定烟曲霉菌生物膜中的时空氧梯度和单细胞代谢活性。氧梯度在烟曲霉菌生物膜成熟过程中不可避免地出现，并且是烟曲霉菌后期生物膜构筑的关键和结果。我们观察到，这些自我诱导的低氧微环境不仅有助于丝状真菌生物膜的成熟，而且还导致了对抗真菌治疗的耐药性。降低烟曲霉菌生物膜底部的氧气水平会增加抗真菌药物的耐药性。我们的结果确定了一个以前未知的丝状真菌生物被膜生理学和当代抗真菌耐药性之间的机制联系。此外，我们证明了在许多细菌生物膜中发现的由动态氧梯度介导的耐药性也延伸到真菌王国。因此，保护细菌和真菌生物被膜中的耐低氧耐药生态位是提高抗菌治疗效果的一个有希望的目标。
Human fungal infections may fail to respond to contemporary antifungal therapies in vivo despite in vitro fungal isolate drug susceptibility. Such a discrepancy between in vitro antimicrobial susceptibility and in vivo treatment outcomes is partially explained by microbes adopting a drug-resistant biofilm mode of growth during infection. The filamentous fungal pathogen Aspergillus fumigatus forms biofilms in vivo, and during biofilm growth it has reduced susceptibility to all three classes of contemporary antifungal drugs. Specific features of filamentous fungal biofilms that drive antifungal drug resistance remain largely unknown. In this study, we applied a fluorescence microscopy approach coupled with transcriptional bioreporters to define spatial and temporal oxygen gradients and single-cell metabolic activity within A. fumigatus biofilms. Oxygen gradients inevitably arise during A. fumigatus biofilm maturation and are both critical for, and the result of, A. fumigatus late-stage biofilm architecture. We observe that these self-induced hypoxic microenvironments not only contribute to filamentous fungal biofilm maturation but also drive resistance to antifungal treatment. Decreasing oxygen levels toward the base of A. fumigatus biofilms increases antifungal drug resistance. Our results define a previously unknown mechanistic link between filamentous fungal biofilm physiology and contemporary antifungal drug resistance. Moreover, we demonstrate that drug resistance mediated by dynamic oxygen gradients, found in many bacterial biofilms, also extends to the fungal kingdom. The conservation of hypoxic drug-resistant niches in bacterial and fungal biofilms is thus a promising target for improving antimicrobial therapy efficacy.