PDF(Pubmed)
Abstract：
Antibiotic resistance has become an urgent threat to health care in recent years. The use of drug delivery systems provides advantages over conventional administration of antibiotics and can slow the development of antibiotic resistance. In the current study, we developed a toxin-triggered liposomal antibiotic delivery system, in which the drug release is enabled by the leukotoxin (LtxA) produced by the Gram-negative pathogen, Aggregatibacter actinomycetemcomitans. LtxA has previously been shown to mediate membrane disruption by promoting a lipid phase change in nonlamellar lipids, such as 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-methyl (N-methyl-DOPE). In addition, LtxA has been observed to bind strongly and nearly irreversibly to membranes containing large amounts of cholesterol. Here, we designed a liposomal delivery system composed of N-methyl-DOPE and cholesterol to take advantage of these interactions. Specifically, we hypothesized that liposomes composed of N-methyl-DOPE and cholesterol, encapsulating antibiotics, would be sensitive to LtxA, enabling controlled antibiotic release. We observed that liposomes composed of N-methyl-DOPE were sensitive to the presence of low concentrations of LtxA, and cholesterol increased the extent and kinetics of content release. The liposomes were stable under various storage conditions for at least 7 days. Finally, we showed that antibiotic release occurs selectively in the presence of an LtxA-producing strain of A. actinomycetemcomitans but not in the presence of a non-LtxA-expressing strain. Together, these results demonstrate that the designed liposomal vehicle enables toxin-triggered delivery of antibiotics to LtxA-producing strains of A. actinomycetemcomitans.
摘要：
近年来，抗生素耐药性已成为医疗保健的紧迫威胁。药物递送系统的使用提供优于常规抗生素施用的优点,并且可以减缓抗生素抗性的发展。在目前的研究中,我们开发了一种毒素触发的脂质体抗生素递送系统，其中药物释放是由革兰氏阴性病原体产生的白细胞毒素（LtxA）实现的，放线菌聚集杆菌。LtxA先前已被证明通过促进非层状脂质的脂质相变来介导膜破坏，例如1,2-二油酰基-sn-甘油基-3-磷酸乙醇胺-N-甲基(N-甲基-DOPE)。此外,已观察到LtxA与含有大量胆固醇的膜强烈且几乎不可逆地结合。这里,我们设计了由N-甲基-DOPE和胆固醇组成的脂质体递送系统,以利用这些相互作用.具体来说,我们假设由N-甲基-DOPE和胆固醇组成的脂质体，封装抗生素，会对LtxA敏感，能够控制抗生素的释放。我们观察到由N-甲基-DOPE组成的脂质体对低浓度的LtxA的存在敏感，胆固醇增加了内容物释放的程度和动力学。脂质体在各种储存条件下稳定至少7天。最后,我们表明，抗生素的释放在放线菌群产生LtxA的菌株存在下选择性地发生，但在非LtxA表达菌株存在下不发生。一起,这些结果表明,设计的脂质体载体能够将毒素触发的抗生素递送至产生LtxA的放线菌群。
