脂多糖干预对军团菌肺炎作用的实验研究

An animal experiment regarding the effect of lipopolysaccharide intervention program on Legionella pneumonia

目的探讨脂多糖干预对军团菌肺炎的作用。方法以C3H/HeN小鼠(6~8周龄)为实验动物,每组8只,雌雄各半。设立脂多糖干预染菌组、脂多糖未干预染菌组和对照组,每组各设12、24和48h3个时间点组。首先对脂多糖干预组小鼠利用大肠埃希菌脂多糖(100ng/只)行腹腔注射干预,其余组腹腔注射生理盐水。24h后与脂多糖未干预组一起气管注射军团菌悬液染菌,对照组给予等量的生理盐水,分别于12、24和48h处死小鼠。解剖小鼠,分离肺脏称重,计算脏器系数(小鼠肺脏重量/体重)。眼眶采血1ml,流式细胞术检测各组外周血单个核细胞Toll样受体4(TLR4)水平,取左肺上叶采用ELISA法检测肿瘤坏死因子-α(TNF-α)、白细胞介素-1β(IL-1β)的含量。结果脂多糖未干预染菌组的肺脏脏器系数高于脂多糖干预染菌组和对照组(P<0.05),脂多糖干预染菌组与对照组间差异无统计学意义。脂多糖干预染菌组与脂多糖未干预染菌组TLR4蛋白均在12h达到高峰,且脂多糖干预组TLR4水平高于脂多糖未干预组(P<0.05),在24、48h两染菌组TLR4表达水平差异无统计学意义。脂多糖干预染菌组TNF-α、IL-1β浓度与对照组间差异无统计学意义,脂多糖未干预染菌组各个时间点TNF-α、IL-1β的分泌水平均高于脂多糖干预染菌组。结论脂多糖干预引起的脂多糖耐受可能会减轻军团菌感染的炎性症状。

Objective To explore the effect of lipopolysaccharide intervention program on Legionella pneumonia. Methods C3H/HeN mice (6-8 weeks old) were used as experimental animals. The mice were randomly divided into lipopolysaccharide intervention, non-lipopolysaccharide intervention and control groups. Each group was again divided into three time points: 12 h, 24 h and 48 h. Mice in the lipopolysaccharide intervention group were intraperitoneally injected with E. coli lipopolysaccharide (100 ng per mice), and the rest groups were intraperitoneally injected with normal saline. After 24 hours, mice in the lipopolysaccharide intervention and the non-intervention groups mice were infected with Legionella by tracheal injection and the control group was given the same amount of saline. All the mice were killed at 12, 24 and 48 hours respectively. The mice were anatomized, lungs of the mice were separated and weighed. Organ coefficients (lung weight/body weight of mice) were calculated. 1 ml Orbital blood was collected. Toll-like receptor 4 (TLR4) levels of peripheral blood mononuclear cells were measured by flow cytometry. The contents of TNF-α and IL-1β in the upper left lung lobe were measured by ELISA. Results In the lung organs, the coefficients of lipopolysaccharide non-intervention group were higher than the other groups and there was no significant difference seen between the lipopolysaccharide intervention group and the controls. TLR4 peaked at 12 hours in both the lipopolysaccharide intervention and the non-intervention groups while the TLR4 level in the intervention group was higher than that in the non-intervention group. There were no significant differences appeared on the TLR4 expression levels between the two Legionella pneumonia modelled groups at 24 or 48 hours. There was no significant difference seen regarding the concentration of TNF-α and IL-1β between the intervention and the control groups. The secretion levels of TNF-α and IL-1β in the non-intervention group were higher than those in the intervention group at each time point. Conclusion The lipopolysaccharide intervention program may alleviate the inflammatory symptoms of Legionella infection.