Department of Chemistry, University of Massachusetts Amherst, 710 North Pleasant Street, Amherst, MA, 01003, United States.
Department of Chemistry, University of Massachusetts Amherst, 710 North Pleasant Street, Amherst, MA, 01003, United States.
Biomaterials. 2023 Nov;302:122344. doi: 10.1016/j.biomaterials.2023.122344. Epub 2023 Oct 10.
Intracellular pathogenic bacteria use immune cells as hosts for bacterial replication and reinfection, leading to challenging systemic infections including peritonitis. The spread of multidrug-resistant (MDR) bacteria and the added barrier presented by host cell internalization limit the efficacy of standard antibiotic therapies for treating intracellular infections. We present a non-antibiotic strategy to treat intracellular infections. Antimicrobial phytochemicals were stabilized and delivered by polymer-stabilized biodegradable nanoemulsions (BNEs). BNEs were fabricated using different phytochemicals, with eugenol-loaded BNEs (E-BNEs) affording the best combination of antimicrobial efficacy, macrophage accumulation, and biocompatibility. The positively-charged polymer groups of the E-BNEs bind to the cell surface of macrophages, facilitating the entry of eugenol that then kills the intracellular bacteria without harming the host cells. Confocal imaging and flow cytometry confirmed that this entry occurred mainly via cholesterol-dependent membrane fusion. As eugenol co-localized and interacted with intracellular bacteria, antibacterial efficacy was maintained. E-BNEs reversed the immunosuppressive effects of MRSA on macrophages. Notably, E-BNEs did not elicit resistance selection after multiple exposures of MRSA to sub-therapeutic doses. The E-BNEs were highly effective against a murine model of MRSA-induced peritonitis with better bacterial clearance (99 % bacteria reduction) compared to clinically-employed treatment with vancomycin. Overall, these findings demonstrate the potential of E-BNEs in treating peritonitis and other refractory intracellular infections.
细胞内病原体利用免疫细胞作为细菌复制和再感染的宿主，导致包括腹膜炎在内的具有挑战性的全身感染。多药耐药（MDR）细菌的传播和宿主细胞内化带来的额外障碍限制了标准抗生素疗法治疗细胞内感染的疗效。我们提出了一种非抗生素策略来治疗细胞内感染。抗菌植物化学物质通过聚合物稳定的可生物降解纳米乳液（BNEs）得到稳定和传递。使用不同的植物化学物质制造 BNEs，其中负载丁香酚的 BNEs（E-BNEs）提供了最佳的抗菌功效、巨噬细胞积累和生物相容性的组合。E-BNEs 的正电荷聚合物基团与巨噬细胞的细胞表面结合，促进丁香酚的进入，从而杀死细胞内细菌而不伤害宿主细胞。共聚焦成像和流式细胞术证实，这种进入主要通过胆固醇依赖性膜融合发生。由于丁香酚与细胞内细菌共定位并相互作用，因此保持了抗菌功效。E-BNEs 逆转了 MRSA 对巨噬细胞的免疫抑制作用。值得注意的是，E-BNEs 在多次暴露于亚治疗剂量的 MRSA 后，没有引发耐药性选择。E-BNEs 对 MRSA 诱导的腹膜炎的小鼠模型非常有效，与万古霉素的临床应用相比，具有更好的细菌清除率（减少 99%的细菌）。总的来说，这些发现表明 E-BNEs 在治疗腹膜炎和其他难治性细胞内感染方面具有潜力。
