School of Life Science and Technology, China Pharmaceutical University, Nanjing, Jiangsu 211198, PR China.
Jiangsu Key Laboratory of Chiral Pharmaceuticals Biosynthesis, College of Pharmacy and Chemistry & Chemical Engineering, Taizhou University 93 Ji Chuan Road, Taizhou 225300, PR China.
Peptides. 2020 Aug;130:170334. doi: 10.1016/j.peptides.2020.170334. Epub 2020 Jun 3.
The development of novel antifungal agents with high efficacy, low drug tolerance and few side effects is urgent. MSI-1 (GIWKFLKKAKKFWK-NH), a cationic antimicrobial peptide, may be an attractive antifungal agent because of its structural characteristics, perfect stability against pH and high-temperature/salt, low toxicity towards mammalian cells and low potential for emergence of drug tolerance. In this study, the antifungal activity of MSI-1 in vitro and in a murine model of cryptococcal meningoencephalitis was evaluated. Zeta potential assay, flow cytometry, fluorescence microscope, transmission electron microscopy and microscale thermophoresis were performed to clarify the mechanisms underlying MSI-1 against C. neoformans. The results showed that MSI-1 exerted effective anti-cryptococcal activity in vitro, with MICs of 8-16 μg/mL and MFCs of 8-32 μg/mL, and in a C neoformans-infected mouse model, with significantly improved animal survival, decreased production of pro-inflammatory cytokines and alleviated lung injury, because the potent and rapid fungicidal activity of MSI-1 could effectively eliminate fungal counts in mouse organs. We confirmed that the positively charged peptide bound to C. neoformans by electrostatic attraction after interacting with glucuronoxylomannan (the primary component of C. neoformans capsule). Subsequently, MSI-1 increased the membrane fluidity of fungal cells and the cell membrane permeability, causing destabilized membrane integrity and leading to the final death of fungi. Collectively, MSI-1 possessed potent anti-cryptococcal activity via its notable membrane disruption effect and may be a potential candidate for use in antifungal infection induced by C. neoformans, especially azole-resistant cryptococcus.
新型高效、低耐药性、低副作用抗真菌药物的开发迫在眉睫。MSI-1（GIWKFLKKAKKFWK-NH）是一种阳离子抗菌肽，由于其结构特征、对 pH 和高温/盐的稳定性、对哺乳动物细胞的低毒性以及对耐药性产生的低潜力，可能成为一种有吸引力的抗真菌药物。在这项研究中，评估了 MSI-1 在体外和隐球菌性脑膜脑炎小鼠模型中的抗真菌活性。通过动电位测定、流式细胞术、荧光显微镜、透射电子显微镜和微量热泳动实验，阐明了 MSI-1 对抗新型隐球菌的作用机制。结果表明，MSI-1 在体外具有有效的抗隐球菌活性，MIC 值为 8-16μg/ml，MFC 值为 8-32μg/ml，在新型隐球菌感染的小鼠模型中，显著提高了动物的存活率，降低了促炎细胞因子的产生，减轻了肺部损伤，因为 MSI-1 的强大而快速的杀菌活性可以有效消除小鼠器官中的真菌计数。我们证实，带正电荷的肽与葡聚糖（新型隐球菌囊的主要成分）相互作用后，通过静电吸引与新型隐球菌结合。随后，MSI-1 增加了真菌细胞的膜流动性和细胞膜通透性，导致膜稳定性不稳定，并最终导致真菌死亡。总的来说，MSI-1 通过显著的膜破坏作用具有强大的抗隐球菌活性，可能是一种有潜力的抗新型隐球菌感染的候选药物，特别是唑类耐药的隐球菌。
