Jiangsu Key Laboratory of Infection and Immunity, Institutes of Biology and Medical Sciences, Soochow University, Suzhou, 215123, Jiangsu, China.
Jiangsu Key Laboratory of Infection and Immunity, Institutes of Biology and Medical Sciences, Soochow University, Suzhou, 215123, Jiangsu, China.
Antiviral Res. 2021 Mar;187:105021. doi: 10.1016/j.antiviral.2021.105021. Epub 2021 Jan 26.
Cathelicidin antimicrobial peptides (human LL-37 and mouse CRAMP) are mainly virucidal to enveloped virus. However, the effects and relative mechanisms of LL-37 and CRAMP on non-enveloped virus are elusive. We herein found that CRAMP expression was significantly up-regulated post non-enveloped Enterovirus 71 (EV71) infection in different tissues of newborn ICR mice, while EV71 replication gradually declined post CRAMP up-regulation, indicating the antiviral potential of cathelicidin against EV71. In vitro antiviral assay showed that LL-37 and CRAMP markedly reduced cytopathic effects (CPE), intracellular viral RNA copy numbers, viral VP1 protein levels, and extracellular virons in U251 cells post EV71 infection, indicating that LL-37 and CRAMP significantly inhibited EV71 replication. Mechanism of action assay showed that LL-37 and CRAMP were not virucidal to EV71, but markedly regulated antiviral immune response in U251 cells. Co-incubation of LL-37 or CRAMP with U251 cells markedly increased the basal interferon-β (IFN-β) expression and interferon regulatory transcription factor 3 (IRF3) phosphorylation, modestly enhanced IFN-β production and IRF3 phosphorylation upon EV71 infection, and significantly reduced interleukin-6 (IL-6) production and p38 mitogen-activated protein kinase (MAPK) activation post EV71 infection. Additionally, LL-37 and CRAMP directly inhibited viral binding to U251 cells. Collectively, LL-37 and CRAMP markedly inhibited EV71 replication via regulating antiviral response and inhibiting viral binding, providing potent candidates for peptide drug development against EV71 infection.
抗菌肽（人源 LL-37 和鼠源 CRAMP）主要对有包膜的病毒具有病毒杀伤作用。然而，LL-37 和 CRAMP 对无包膜病毒的作用和相关机制仍不清楚。我们在此发现，无包膜肠道病毒 71 型（EV71）感染新生 ICR 小鼠的不同组织后，CRAMP 的表达显著上调，而 EV71 复制在 CRAMP 上调后逐渐下降，表明抗菌肽对 EV71 具有抗病毒潜力。体外抗病毒测定表明，LL-37 和 CRAMP 可显著减轻 EV71 感染 U251 细胞后的细胞病变效应（CPE）、细胞内病毒 RNA 拷贝数、病毒 VP1 蛋白水平和细胞外病毒粒子，表明 LL-37 和 CRAMP 可显著抑制 EV71 复制。作用机制测定表明，LL-37 和 CRAMP 对 EV71 无病毒杀伤作用，但可显著调节 U251 细胞中的抗病毒免疫反应。LL-37 或 CRAMP 与 U251 细胞共孵育可显著增加基础干扰素-β（IFN-β）表达和干扰素调节转录因子 3（IRF3）磷酸化，适度增强 EV71 感染时 IFN-β的产生和 IRF3 磷酸化，并显著减少 EV71 感染后的白细胞介素-6（IL-6）产生和 p38 丝裂原活化蛋白激酶（MAPK）激活。此外，LL-37 和 CRAMP 可直接抑制病毒与 U251 细胞的结合。总之，LL-37 和 CRAMP 通过调节抗病毒反应和抑制病毒结合，显著抑制 EV71 复制，为开发针对 EV71 感染的肽类药物提供了有力候选物。
