目的:吸入性噬菌体疗法作为多药耐药铜绿假单胞菌引起的呼吸道感染的潜在治疗选择,但在理解剂量反应效应方面存在明显的差距。这项研究的目的是研究通过肺部途径递送的假单胞菌靶向噬菌体PEV31在小鼠肺部感染模型中的剂量反应效应。
方法:嗜中性粒细胞减少性BALB/c小鼠经气管内途径感染多药耐药铜绿假单胞菌(2×104个集落形成单位),然后用3种不同剂量7.5×104的PEV31治疗(A组),5×106(B组),和5×108(C组)斑块形成单元,或磷酸盐缓冲盐水在接种后2小时。小鼠(n=5-7)在感染后2小时和24小时安乐死,和肺,肾脏,脾,脾肝脏,支气管肺泡灌洗液,并收集血液进行细菌和噬菌体计数。
结果:感染后24小时,所有噬菌体处理组的肺部细菌负荷均显著减少1.3-1.9log10,与所递送的噬菌体剂量无关.噬菌体复制的程度与给药剂量呈负相关,A组的log10滴度分别增加6.2、2.7和9,B,C,分别。感染后24小时收获的肺匀浆样品中的噬菌体抗性细菌亚群随着治疗剂量的增加而增加(即30%,74%,A-C组分别为91%)。然而,突变体对环丙沙星的敏感性增加,抽搐运动受损,并减少了蓝绿色颜料的产量。随着PEV31治疗剂量的增加,炎性细胞因子(IL-1β和IL-6和TNF-α)的表达受到抑制。
结论:本研究提供了吸入性噬菌体疗法的剂量反应效应,可指导治疗人类铜绿假单胞菌呼吸道感染的剂量选择。
OBJECTIVE: Inhaled phage therapy has been revisited as a potential treatment option for respiratory infections caused by multidrug-resistant Pseudomonas aeruginosa; however, there is a distinct gap in understanding the dose-response effect. The aim of this study was to investigate the dose-response effect of Pseudomonas-targeting phage PEV31 delivered by the pulmonary route in a mouse lung infection model.
METHODS: Neutropenic BALB/c mice were infected with multidrug-resistant P. aeruginosa (2 × 104 colony-forming units) through the intratracheal route and then treated with PEV31 at three different doses of 7.5 × 104 (Group A), 5 × 106 (Group B), and 5 × 108 (Group C) plaque-forming units, or phosphate-buffered saline at 2 hours postinoculation. Mice (n = 5-7) were euthanized at 2 hours and 24 hours postinfection, and lungs, kidneys, spleen, liver, bronchoalveolar lavage fluid, and blood were collected for bacteria and phage enumeration.
RESULTS: At 24 hours postinfection, all phage-treated groups exhibited a significant reduction in pulmonary bacterial load by 1.3-1.9 log10, independent of the delivered phage dose. The extent of phage replication was negatively correlated with the dose administered, with log10 titre increases of 6.2, 2.7, and 9 for Groups A, B, and C, respectively. Phage-resistant bacterial subpopulations in the lung homogenate samples harvested at 24 hours postinfection increased with the treatment dose (i.e. 30%, 74%, and 91% in respective Groups A-C). However, the mutants showed increased susceptibility to ciprofloxacin, impaired twitching motility, and reduced blue-green pigment production. The expression of the inflammatory cytokines (IL-1ß and IL-6, and TNF-α) was suppressed with increasing PEV31 treatment dose.
CONCLUSIONS: This study provides the dose-response effect of inhaled phage therapy that may guide dose selection for treating P. aeruginosa respiratory infections in humans.