猪β防御素-2对猪链球菌感染小鼠的治疗效果评价

doi:10.11843/j.issn.0366-6964.2020.12.025

摘要/Abstract

摘要： 防御素是一种广泛分布于动植物中的阳离子小肽，是哺乳动物先天性免疫防御系统的重要成分，具有广谱抗菌、抗病毒和抗真菌活性。猪β防御素-2（porcine β-defensin-2，PBD-2）是猪表达的天然防御素之一，在体外具有良好的抗菌活性。本研究旨在评价PBD-2在动物体内对重要的人兽共患病原菌猪链球菌感染的治疗效果，为评估PBD-2成为治疗性药物的潜在价值提供依据。首先，在体外检测了PBD-2对猪链球菌临床分离菌株SC-19的杀菌活性，并且在鼠源巨噬细胞（RAW264.7）上检测了PBD-2的细胞毒性。随后，选取4~6周龄，体重在18~22 g的C57雌鼠，检测了PBD-2处理组和PBS对照组小鼠（n≥6）感染猪链球菌SC-19后的存活率、组织载菌量、炎性细胞因子水平和病理变化。结果表明，PBD-2（25~200 μg·mL^-1）可显著地抑制猪链球菌SC-19生长（P<0.05），且抑制作用随浓度升高而增强，同时，对RAW细胞无显著的毒性作用（P>0.05）。在体内，PBD-2处理能有效降低小鼠感染猪链球菌SC-19后的死亡率，并且显著降低小鼠感染细菌后的脑、肺、脾组织和血液中的细菌载量，以及血清中炎性细胞因子IL-6、IL-12和TNF-α的水平（P<0.05）。同时，PBD-2治疗也显著降低了小鼠感染细菌后肺和脾组织的病理变化程度（P<0.05）。这些结果说明，PBD-2在体外具有良好的抗猪链球菌的活性，无显著细胞毒性，同时，在小鼠体内对猪链球菌感染具有治疗效果，提示，PBD-2具有进一步开发为治疗性药物的潜力。

关键词: 猪β防御素-2, 细菌感染, 治疗, 猪链球菌

Abstract: Defensin is a small cationic peptide widely distributed in animals and plants. It is an important component of the innate immune defense system of mammals. It has a broad spectrum of antibacterial, antiviral and antifungal activities. Porcine β-defensin-2 (PBD-2) is one of the natural defensins expressed in pigs and has good antibacterial activity in vitro. The purpose of this study is to evaluate the therapeutic effect of PBD-2 in the treatment of Streptococcus suis infection in animals and to provide more insights for evaluating the value of PBD-2 as a therapeutic drug. Firstly, the bactericidal activity of PBD-2 against S. suis clinical isolate SC-19 was measured in vitro, and the cytotoxicity of PBD-2 was tested on mouse-derived macrophages (RAW264.7). Subsequently, C57 female mice aged 4-6 weeks and weighing between 18-22 g infected with S. suis SC-19 were treated with PBD-2 or PBS (n ≥ 6). The survival rate of mice, and the bacteria loads, inflammatory cytokine levels, and pathological changes of tissues were determined. The results showed that PBD-2 (25-200 μg·mL^-1) could significantly inhibit the growth of S. suis SC-19 in a concentration-dependent manner (P<0.05). At the same time, PBD-2 had no significant toxic effect on RAW cells (P>0.05). The in vivo study revealed that PBD-2 treatment could effectively reduce the mortality of mice infected with S. suis SC-19. At the same time, PBD-2 treatment significantly reduced bacteria loads in brain, lung, spleen and blood of mice, and decreased the levels of inflammatory cytokines IL-6, IL-12 and TNF-α in mouse sera (P<0.05). At the same time, PBD-2 treatment also significantly alleviated the degree of pathological damages in lung and spleen tissues of mice infected with bacteria (P<0.05). These results indicate that PBD-2 confers great resilience to S. suis in vitro without significant cytotoxicity, while it also exhibits a therapeutic effect on S. suis infection in mice, suggesting that the use of PBD-2 as a therapeutic drug and substitutes for antibiotics is of an excellent prospect.

Key words: porcine β-defensin-2, bacterial infection, treatment, Streptococcus suis

中图分类号:

S855.11

王安田, 黄靖, 宋炳晓, 孙瑜凡, 周锐, 黎璐. 猪β防御素-2对猪链球菌感染小鼠的治疗效果评价[J]. 畜牧兽医学报, 2020, 51(12): 3160-3170.

WANG Antian, HUANG Jing, SONG Bingxiao, SUN Yufan, ZHOU Rui, LI Lu. Evaluation of Therapeutic Effect of Porcine β-defensin-2 on Streptococcus suis Infection[J]. Acta Veterinaria et Zootechnica Sinica, 2020, 51(12): 3160-3170.

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