Department of Chemical Sciences, Bernal Institute, University of Limerick, Ireland.
Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, Ireland; APC Microbiome Ireland, Cork, Ireland.
Eur J Pharm Biopharm. 2022 Jul;176:199-210. doi: 10.1016/j.ejpb.2022.05.016. Epub 2022 May 29.
The bacteriocin lacticin 3147 (lacticin) has shown activity against clinically relevant and antimicrobial-resistant bacteria such as Listeria monocytogenes and Clostridioides difficile. It is composed of two peptides, Ltnα and Ltnβ, which work together to form pores in the membrane of Gram-positive bacteria. Lacticin possesses poor aqueous solubility and is degraded by intestinal proteases. In a previous study, peptides encapsulated into solid lipid nanoparticles (SLNs) displayed activity in aqueous media and were protected from enzyme degradation but showed a low encapsulation efficiency (EE%) for Ltnα. In this study, however, lacticin was encapsulated into SLNs both individually (single occupancy, SLNα + SLNβ) and together (double occupancy SLNαβ) via a nanoprecipitation technique. This achieved SLNs of uniform size with an EE% above 87% for both peptides at loadings of 9 or 18 mg/g of lipid under single occupancy or double occupancy respectively. SLNαβ dispersions displayed more potent activity at 3.13 and 1.56 µg/ml lacticin than SLNα + SLNβ dispersions. Thus, the SLNαβ dispersion was chosen for further analysis. SLNαβ dispersions showed no cytotoxicity to endothelial cells. The SLN release media (fasted state simulated intestinal fluid; FaSSIF) retained activity at 1 h and 3 h indicating that lacticin may be sufficiently protected from proteases present in the duodenum. Finally, a reconstituted freeze-dried SLNαβ dispersion was stable and achieved 99.99% bacterial killing at 3.125 µg/ml lacticin. Thus, an SLN based lacticin delivery system was developed, potentially enabling oral administration of the bacteriocin to the colon to treat local infections such as C. difficile.
细菌素乳链菌肽 3147（乳链菌肽）已显示出对临床相关和抗微生物耐药细菌（如单核细胞增生李斯特菌和艰难梭菌）的活性。它由两种肽组成，Ltnα 和 Ltnβ，它们共同作用在革兰氏阳性菌的膜上形成孔。乳链菌肽的水溶性差，并且被肠道蛋白酶降解。在以前的研究中，包封在固体脂质纳米粒（SLN）中的肽在水介质中显示出活性，并且免受酶降解的影响，但对 Ltnα 的包封效率（EE%）较低。然而，在这项研究中，乳链菌肽通过纳米沉淀技术分别（单占据，SLNα+SLNβ）和一起（双占据 SLNαβ）包封到 SLN 中。这实现了粒径均匀的 SLN，对于单占据或双占据时的 9 或 18mg/g 脂质载量，两种肽的 EE%均超过 87%。SLNαβ 分散体在 3.13 和 1.56µg/ml 乳链菌肽下显示出比 SLNα+SLNβ 分散体更强的活性。因此，选择 SLNαβ 分散体进行进一步分析。SLNαβ 分散体对内皮细胞没有细胞毒性。SLN 释放介质（空腹状态模拟肠液；FaSSIF）在 1 小时和 3 小时时保持活性，表明乳链菌肽可能足够受到十二指肠中存在的蛋白酶的保护。最后，重建的冷冻干燥 SLNαβ 分散体稳定，在 3.125µg/ml 乳链菌肽下实现了 99.99%的细菌杀灭。因此，开发了基于 SLN 的乳链菌肽递送系统，可能能够使该细菌素经口递送至结肠以治疗局部感染，如艰难梭菌。
