Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States.
Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States.
ACS Infect Dis. 2023 Nov 10;9(11):2316-2324. doi: 10.1021/acsinfecdis.3c00415. Epub 2023 Oct 13.
Antimicrobial resistance poses a serious threat to global health, necessitating research for alternative approaches to treating infections. Nitric oxide (NO) is an endogenously produced molecule involved in multiple physiological processes, including the response to pathogens. Herein, we employed microscopy- and fluorescence-based techniques to investigate the effects of NO delivered from exogenous NO donors on the bacterial cell envelopes of pathogens, including resistant strains. Our goal was to assess the role of NO donor architecture (small molecules, oligosaccharides, dendrimers) on bacterial wall degradation to representative Gram-negative bacteria (, ) and Gram-positive bacteria (, ) upon treatment. Depending on the NO donor, bactericidal NO doses spanned 1.5-5.5 mM (total NO released). Transmission electron microscopy of bacteria following NO exposure indicated extensive membrane damage to Gram-negative bacteria with warping of the cellular shape and disruption of the cell wall. Among the small-molecule NO donors, those providing a more extended release ( = 120 min) resulted in greater damage to Gram-negative bacteria. In contrast, rapid NO release ( = 24 min) altered neither the morphology nor the roughness of these bacteria. For Gram-positive bacteria, NO treatments did not result in any drastic change to cellular shape or membrane integrity, despite permeation of the cell wall as measured by depolarization assays. The use of positively charged quaternary ammonium (QA)-modified NO-releasing dendrimer proved to be the only NO donor system capable of penetrating the thick peptidoglycan layer of Gram-positive bacteria.
抗菌药物耐药性对全球健康构成严重威胁，因此需要研究替代方法来治疗感染。一氧化氮（NO）是一种内源性产生的分子，参与多种生理过程，包括对病原体的反应。在此，我们采用显微镜和荧光技术研究了外源性 NO 供体释放的 NO 对包括耐药菌株在内的病原体细菌包膜的影响。我们的目标是评估 NO 供体结构（小分子、寡糖、树状大分子）对代表性革兰氏阴性菌（、）和革兰氏阳性菌（、）细胞壁降解的作用。根据 NO 供体的不同，杀菌剂量的 NO 范围为 1.5-5.5 mM（总释放的 NO）。NO 暴露后对细菌进行透射电子显微镜观察表明，革兰氏阴性菌的细胞膜严重受损，细胞形状扭曲，细胞壁破裂。在小分子 NO 供体中，那些具有更长释放时间（=120 分钟）的供体对革兰氏阴性菌造成更大的损伤。相比之下，快速释放的 NO（=24 分钟）既没有改变这些细菌的形态，也没有改变其粗糙度。对于革兰氏阳性菌，尽管通过去极化测定法测量到细胞壁通透性增加，但 NO 处理并没有导致细胞形状或膜完整性发生任何剧烈变化。带正电荷的季铵（QA）修饰的 NO 释放树状大分子的使用被证明是唯一能够穿透革兰氏阳性菌厚肽聚糖层的 NO 供体系统。
