Kong Jingchun, Wang Yue, Liu Yan, Chen Weijun, Han Yijia, Zhou Huijing, Zhang Xiaodong, Zhou Beibei, Zhou Tieli, Zheng Jiayin
Department of Clinical Laboratory, Key Laboratory of Clinical Laboratory Diagnosis and Translational Research of Zhejiang Province, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China.
Department of Medical Lab Science, School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, Zhejiang Province, China.
BMC Microbiol. 2025 Mar 31;25(1):183. doi: 10.1186/s12866-025-03906-8.
Carbapenem-resistant Escherichia coli (CREC) is one of the most significant clinical pathogens, primarily emerging owing to the widespread use of broad-spectrum antibiotics. Antimicrobial resistance is a major global health challenge that prolongs treatment duration and increases healthcare costs. This study evaluated the antibacterial and anti-inflammatory effects of the antimicrobial peptide Lf-KR against CREC.
Broth microdilution method, growth curve analysis, and time-kill assays were performed to evaluate the antibacterial activity of Lf-KR against CREC. The working mechanism of Lf-KR was elucidated using N-phenyl-1-naphthylamine, propidium iodide fluorochrome, and lipopolysaccharide-binding assays. qRT-PCR was used to assess the peptide's effects on the expression of pro-inflammatory cytokines expression during infection. Furthermore, the safety and stability of Lf-KR were assessed by testing its cytotoxicity, hemolytic activity, and antibacterial stability under various conditions. The Galleria mellonella infection model was applied to evaluate the in vivo activity of Lf-KR.
In vitro tests showed that Lf-KR exhibited potent antibacterial activity against CREC, with the minimum inhibitory concentrations of ranging from 4-8 µg/mL and minimum bactericidal concentrations 4-16 µg/mL. Mechanistically, Lf-KR induced bacterial cell death by disrupting the bacterial membrane. Furthermore, Lf-KR significantly reduced the expression of pro-inflammatory cytokine genes, including IL-1β, IL-6, and TNF-α, in RAW 264.7 macrophage cells infected with CREC. Lf-KR concentrations < 128 µg/mL showed no significant cytotoxicity or erythrocyte hemolytic activity. Lf-KR antibacterial activity was stable across a wide temperature range (- 80 °C to 65 °C), although it was more susceptible to inhibition by fetal bovine serum. The G. mellonella infection model further demonstrated the robust antimicrobial activity of Lf-KR.
This study demonstrated that the antimicrobial peptide Lf-KR is a highly promising antimicrobial and anti-inflammatory agent against CREC, with potential applications in combating multi drug-resistant bacterial infections.
耐碳青霉烯类大肠杆菌（CREC）是最重要的临床病原体之一，主要因广谱抗生素的广泛使用而出现。抗菌药物耐药性是一项重大的全球健康挑战，会延长治疗时间并增加医疗成本。本研究评估了抗菌肽Lf-KR对CREC的抗菌和抗炎作用。
采用肉汤微量稀释法、生长曲线分析和时间杀菌试验来评估Lf-KR对CREC的抗菌活性。使用N-苯基-1-萘胺、碘化丙啶荧光染料和脂多糖结合试验阐明Lf-KR的作用机制。采用qRT-PCR评估该肽在感染期间对促炎细胞因子表达的影响。此外，通过测试其细胞毒性、溶血活性以及在各种条件下的抗菌稳定性来评估Lf-KR的安全性和稳定性。应用大蜡螟感染模型评估Lf-KR的体内活性。
体外试验表明，Lf-KR对CREC表现出强大的抗菌活性，最低抑菌浓度为4-8μg/mL，最低杀菌浓度为4-16μg/mL。从机制上讲，Lf-KR通过破坏细菌膜诱导细菌细胞死亡。此外，Lf-KR显著降低了感染CREC的RAW 264.7巨噬细胞中促炎细胞因子基因（包括IL-1β、IL-6和TNF-α）的表达。浓度低于128μg/mL的Lf-KR未显示出明显的细胞毒性或红细胞溶血活性。Lf-KR的抗菌活性在较宽的温度范围（-80°C至65°C）内稳定，尽管它更容易受到胎牛血清的抑制。大蜡螟感染模型进一步证明了Lf-KR强大的抗菌活性。
本研究表明，抗菌肽Lf-KR是一种极具前景的抗CREC抗菌和抗炎剂，在对抗多重耐药细菌感染方面具有潜在应用价值。
