溶菌酶对头孢他啶诱导的福氏志贺氏菌内毒素释放的抑制作用

Inhibitory effect of egg white lysozyme on ceftazidime induced release of lipopolysaccharide from Shigella dysenteriae

目的 :通过体外及动物体内实验研究溶菌酶 (L ZM)对头孢他啶 (CFT)诱导的福氏志贺氏菌内毒素(L PS)释放的抑制作用。方法 :在营养肉汤或稀释血液培养的福氏志贺氏菌中加入 L ZM或 CFT作用一定时间后 ,将细菌悬液离心 ,收集培养上清液 ,测定释放到上清液中的 L PS浓度 ;将稀释血液培养上清加入到巨噬细胞中 ,采用经放线菌素 D增敏的 L92 9细胞杀伤实验测定肿瘤坏死因子 α(TNFα)的诱生能力。给小鼠腹腔注射角叉菜胶 1 2 h后 ,将营养肉汤培养上清稀释 1 0倍经尾静脉注入小鼠体内 ,采用经放线菌素 D增敏的L 92 9细胞杀伤实验测定小鼠血浆中 TNFα的浓度。给家兔腹腔注射福氏志贺氏菌肉汤培养悬液 3h后 ,分别给各组家兔腹腔注射 CFT或 CFT与 L ZM。于给药后 2、4和 6 h心脏取血 ,离心后分离血浆 ,测定各组家兔血浆中 L PS的浓度及 TNFα和一氧化氮 (NO)的浓度。结果 :营养肉汤培养中 CFT(5 0和 1 0 0 m g/ L )可导致较高浓度的 L PS释放到培养上清液中 ,将该上清液静脉注入小鼠体内 ,产生大量的 TNFα;L ZM与 CFT联合用药可降低培养上清液中的 L PS浓度 ,并减少小鼠体内 TNFα的产生。在血液培养系统中 ,CFT(5 0和1 0 0 mg/ L)可导致较高浓度的内毒素释放到培养上清液中 。

Objective: To investigate the inhibition of lysozyme(LZM) on ceftazidime(CFT)induced lipopolysaccharide(LPS) release through experiments both in vitro and in vivo. Methods: Shigella dysenteriae ATCC 51067 which was cultured in the nutrition broth or the diluted rabbit blood was treated with CFT, a βlactam antibiotic, alone or in combination with LZM. The culture supernatants were collected by centrifuge at 3 hours after addition of CFT. The concentrations of LPS in the supernatants were tested.The diluted rabbit blood culture supernatants were added into RAW 264 7 cells, a macrophage cell line. Tumor necrosis factorα(TNFα) productivity of the supernatants from the cell cultures was assayed with dye ingestion methods. Specific pathogenfree male institute for cancer research(ICR) mice were challenged with intravenous(i.v.) injection of the nutrition broth culture supernatants. TNFα induced in mice was assayed with dye ingestion methods. Rabbits were challenged with intraperitoned injection of Shigella dysenteriae nutrition broth culture suspension, then CFT or CFT and LZM were intraperitoned injected for various groups of rabbits 3 hours later. LPS, TNFα and nitric oxide(NO) were investigated in the rabbit plasm. Results: CFT(50 mg/L, 100 mg/L) caused high concentrations of LPS in the culture supernatants. The nutrition broth culture supernatants induced high level of TNFα production in mouse plasm. The diluted rabbit blood culture supernatants induced high level of TNFα production in RAW 264 7 cells. LZM in combination with CFT resulted in a decreased LPS concentration in the culture supernatants as well as a low TNFα production both in mouse plasm and in RAW 264 7 cells. The combination of LZM with CFT could abate LPS concentration and reduce release of inflammatory substances assessed by TNFα and NO in rabbit plasm. Conclusion: LZM may inhibit CFTinduced LPS release from Shigella dysenteriae.