噬菌体AB3及其脂质体包被液应用于耐碳青霉烯类鲍氏不动杆菌感染的实验研究

Experimental research on application of bacteriophage AB3 and its liposome coating solution in carbapenem-resistant Acinetobacter baumannii infection

目的观察噬菌体AB3在耐碳青霉烯类鲍氏不动杆菌(CRAB)肺部感染小鼠模型中的疗效、代谢规律、对宿主免疫功能的影响,以及脂质体包被对噬菌体AB3在肺组织内存留时间的影响。方法建立CRAB肺部感染小鼠模型,通过滴鼻、肌内注射及腹腔注射3种途径分别将噬菌体AB3注入小鼠体内,观察其在肺组织内的代谢规律及产生中和抗体的效价,确定最佳给药途径并观察其疗效;通过检测小鼠血清细胞因子的水平,了解噬菌体AB3对宿主免疫功能的影响;通过制备脂质体包被液,进一步延长噬菌体AB3在小鼠肺组织中的存留时间。结果滴鼻途径进入的噬菌体AB3,240 min时仍可测出其滴度,长于另2种给药途径,d 7产生低效价的中和抗体,d 28之后中和抗体效价逐渐下降为0,而另2种给药途径的中和抗体效价从d 7开始逐渐增高;噬菌体AB3滴鼻组小鼠给药5 wk后,血清IFN-γ含量明显高于对照组[(280±33)ng·L^(-1) vs.(224±27)ng·L^(-1),P<0.05];噬菌体AB3治疗组小鼠肺组织结构基本正常,存活率明显高于对照组(90%vs.0,P<0.01);噬菌体AB3脂质体包被液经过滴鼻途径进入小鼠体内,在肺组织中的存留时间可延长至300 min,相比未包被组d 7产生更低效价的中和抗体,d 14后中和抗体效价逐渐下降为0,小鼠存活率明显高于对照组(80%vs.0,P<0.01),而与未包被组存活率相比无显著差异(80%vs.90%,P>0.05)。结论噬菌体AB3不仅可有效治疗CRAB肺部感染,还能增强宿主细胞免疫功能。经鼻途径是最佳的给药途径,脂质体包被液可有效延长噬菌体AB3在肺组织内的存留时间。

AIM To observe the efficacy, metabolic principle, effects on host＇s immune functions of bacteriophage AB3 in carbapenem-resistant Acinetobacter baumarmii （CRAB） pulmonary infection and the retention time of bacteriophage AB3 in pulmonary tissues by preparing the liposome, coating solution. METHODS A model of mice with CRAB pulmonary infection was established. The metabolic principle in pulmonary tissues and neutralizing antibody titer of bacteriophage AB3 were observed by administration routes of nasal dripping, intramuscular injection, and intraperitoneal injection to determine the optimal administration route and efficacy. The cytokine level in serum was detected to observe the effects of bacteriophage AB3 on host＇s immune functions, and the liposome coating solution was prepared to extend the retention time of bacteriophage AB3 in pulmonary tissues. RESULTS With nasal dripping, bacteriophage AB3 was retained in pulmonary tissues for the longest duration （detectable in 240 min）, and neutralizing low-titer antibodies were produced on d 7, and the titer gradually decreased to 0 after d 28. While for the other two administration routes, the titer gradually increased since d 7. After mice had been treated with bacteriophage AB3 by nasal dripping for 5 wk, the serum IFN-γ level was significantly higher than that of the control group （（280 ＋ 33） ng·L-1 vs. （224±27） ng·L-1, P 〈 0.05） . The pulmonary tissues of mice treated with bacteriophage AB3 were basically normal, and the survival rate was significantly higher than that of the control group （90% vs. 0, P 〈 0.01） . After the bacteriophage AB3 liposome coating solution was administrated by nasal dripping, the retention time of the solution in pulmonary tissues was extended to 300 min, lower-titer neutralizing antibodies were produced on d 7, the titer was decreased to 0 after d 14, and the survival rate of mice was significantly higher than that of the control group （80% vs. 0, P 〈 0.01）, but there was no significant difference as compared with the survival rate of the uncoated group （80% vs. 90%, P 〉 0.05） . CONCLUSION Bacteriophage AB3 can both treat CRAB pulmonary infection effectively and increase host＇s cell immune functions. The optimal administration route is nasal dripping. The liposome coating solution can efficiently extend the retention time of baeteriphage AB3 in pulmonary tissues.