Background: Leishmaniasis is a neglected disease, and the current therapeutic arsenal for its treatment is seriously limited by high cost and toxicity. Nanostructured lipid carriers (NLCs) represent a promising approach due to high drug loading capacity, controlled drug release profiles and superior stability. Here, we explore the efficacy of a unique pH-sensitive amphotericin B-loaded NLC (AmB-NLC) in Leishmania braziliensis infection in vitro and in vivo.
Methods and Results: AmB-NLC was assessed by dynamic light scattering and atomic force microscopy assays. The carrier showed a spherical shape with a nanometric size of 242.0 ± 18.3 nm. Zeta potential was suggestive of high carrier stability (− 42.5 ± 1.5 mV), and the NLC showed ∼ 99% drug encapsulation efficiency (EE%). In biological assays, AmB-NLC presented a similar IC₅₀ as free AmB and conventional AmB deoxycholate (AmB-D) (11.7 ± 1.73; 5.3 ± 0.55 and 13 ± 0.57 ng/mL, respectively), while also presenting higher selectivity index and lower toxicity to host cells, with no observed production of nitric oxide or TNF-α by in vitro assay. Confocal microscopy revealed the rapid uptake of AmB-NLC by infected macrophages after 1h, which, in association with more rapid disruption of AmB-NLC at acidic pH levels, may directly affect intracellular parasites. Leishmanicidal effects were evaluated in vivo in BALB/c mice infected in the ear dermis with L. braziliensis and treated with a pentavalent antimonial (Sb⁵⁺), liposomal AmB (AmB-L) or AmB-NLC. After 6 weeks of infection, AmB-NLC treatment resulted in smaller ear lesion size in all treated mice, indicating the efficacy of the novel formulation.
Conclusion: Here, we preliminarily demonstrate the effectiveness of an innovative and cost-effective AmB-NLC formulation in promoting the killing of intracellular L. braziliensis. This novel carrier system could be a promising alternative for the future treatment of cutaneous leishmaniasis.



中文翻译：

---

一种新型两性霉素 B 纳米结构脂质载体治疗巴西利什曼原虫感染的体外和体内疗效评价

背景：利什曼病是一种被忽视的疾病，目前治疗该病的治疗手段受到高成本和毒性的严重限制。纳米结构脂质载体 (NLC) 因其高载药能力、受控的药物释放曲线和卓越的稳定性而代表了一种有前途的方法。在这里，我们探索了一种独特的 pH 敏感型两性霉素 B 负载 NLC (AmB-NLC)在体外和体内对巴西利什曼原虫感染的疗效。
方法和结果：AmB-NLC 通过动态光散射和原子力显微镜分析进行评估。载体呈球形，纳米尺寸为 242.0 ± 18.3 nm。Zeta 电位表明载流子稳定性高（- 42.5 ± 1.5 mV），NLC 显示 99% 的药物包封率（EE%）。在生物测定中，AmB-NLC 呈现出类似的 IC ₅₀作为游离 AmB 和常规 AmB 脱氧胆酸盐 (AmB-D)（分别为 11.7 ± 1.73；5.3 ± 0.55 和 13 ± 0.57 ng/mL），同时还表现出更高的选择性指数和对宿主细胞更低的毒性，没有观察到硝酸的产生通过体外测定法测定氧化物或 TNF-α。共聚焦显微镜显示 AmB-NLC 在 1 小时后被感染的巨噬细胞快速摄取，这与在酸性 pH 水平下更快速地破坏 AmB-NLC 相关，可能直接影响细胞内寄生虫。在 BALB/c 小鼠耳部真皮感染巴西利什曼原虫并用五价锑（Sb ⁵⁺)、脂质体 AmB (AmB-L) 或 AmB-NLC。感染 6 周后，AmB-NLC 治疗导致所有治疗小鼠的耳部病变尺寸更小，表明新制剂的功效。
结论：在这里，我们初步证明了一种创新且具有成本效益的 AmB-NLC 制剂在促进细胞内L. braziliensis杀灭方面的有效性。这种新型载体系统可能是未来治疗皮肤利什曼病的有希望的替代方案。