茶多酚对嗜水气单胞菌致病力的抑制作用

Inhibitory Effect of Tea Polyphenols on the Pathogenicity of Aeromonas hydrophila

针对嗜水气单胞菌污染水产品所致动物感染和消费者食源性疾病等问题,筛选能够抑制嗜水气单胞菌致病力的天然产物茶多酚。溶血试验表明茶多酚对气溶素溶血活性具有直接抑制作用,通过荧光热漂移和七聚体形成试验分析其作用机制。结果表明,茶多酚虽在128μg/mL以下不抑制嗜水气单胞菌的生长,但能在1~8μg/mL直接抑制其主要毒力蛋白气溶素的溶血活性。荧光热漂移和七聚体试验发现,茶多酚通过与气溶素直接结合,降低了气溶素七聚体的形成并抑制其活性。细胞试验结果表明,4~8μg/mL茶多酚能对气溶素导致的人肺癌上皮细胞死亡具有显著的保护作用。此外,50 mg/kg茶多酚治疗可使斑点叉尾鮰嗜水气单胞菌感染模型的存活率提高至60%。综上,茶多酚通过直接与气溶素结合,抑制气溶素形成功能性七聚体而降低其活性,从而显著降低嗜水气单胞菌的体内、外致病力。研究结果提示茶多酚可作为抗生素替代或辅助药物用于治疗嗜水气单胞菌相关感染。

The purpose of this study was to screen new drugs that can inhibit the pathogenesis of Aeromonas hydrophila and eliminate infections caused by A.hydrophila contaminated aquatic products.The results showed that tea polyphenols had no role on bacterial growth at concentrations lower than 128μg/mL,but tea polyphenols could inhibit the hemolytic activity of aerolysin at concentrations ranging from 1-8μg/mL.The results of thermal shift and heptamer formation assays showed that tea polyphenols could inhibit the formation of functional heptamer by directly binding to aerolysin and results in loss of activity.Cell viability assays showed that tea polyphenols of 4μg/mL and 8μg/mL could provide a significant protection to A549 cells from aerolysin mediated cell injury.Moreover,experimental therapeutics found that tea polyphenols at a dosage of 50 mg/kg could increase the survival rate of channel catfish infected with A.hydrophila to 60%.The above experiments showed that tea polyphenols directly bind to aerolysin and inhibit the activity of aerolysin by reducing the formation of functional heptamer,and tea polyphenols can significantly reduce the pathogenicity of A.hydrophila both in vitro and in vivo.This study suggests that tea polyphenols can be used as an alternative or adjuvant therapy to antibiotics for the treatment of A.hydrophila-related infections.