细菌内毒素耐受小鼠肝细胞内信号转导相关分子的表达变化  

Modulation of signal transduction-associated molecules in liver cells of bacterial endotoxin tolerant mice

作　　者：栾洁[1] 周炳荣[1] 丁惠[1] 戚中田[1] 

机构地区：[1]第二军医大学微生物学教研室,医学微生物学重点实验室,上海200433

出　　处：《微生物与感染》2006年第4期225-228,237,共5页Journal of Microbes and Infections

摘　　要：目的探讨细菌脂多糖(LPS)相关的信号转导分子在内毒素耐受小鼠肝细胞内的变化和作用。方法将实验小鼠随机分为3大组:敏感组以LPS(2μg)合并半乳糖胺(D-GalN)直接攻击;耐受组预先以LPS(0．1μg)注射,再在不同耐受时间点(3 h、1 d、2 d、7 d)以LPS(2μg)/D-GalN联合攻击。对照组注射生理盐水、D-GalN或LPS(0．1μg);利用反转录-聚合酶链反应(RT-PCR)及蛋白质印迹法(Western印迹法)测定各信号分子在转录和表达水平的变化。结果LPS刺激可显著诱导敏感组小鼠肝细胞的Toll样受体(TLR)-4基因转录和蛋白表达;而在LPS预处理的耐受组,TLR-4 mRNA和蛋白的水平均明显低于敏感组(P＜0．01);耐受组中白细胞介素受体相关激酶1(IRAK-1)基因的表达水平也比敏感组明显低(P＜0．01)。但是肿瘤坏死因子受体相关因子-6(TRAF-6)的表达水平则不受LPS预处理的影响。NF-κB组分分析显示,敏感组IκB的降解明显高于耐受组;耐受组的p65亚基表达显著降低,而p50亚基表达升高。结论内毒素耐受可使NF-κB的p65亚基表达下调、p50亚基表达升高和抑制IκB的降解,而TLR-4和IRAK-1的表达下调是诱导产生内毒素耐受性的重要因素。Objective To investigate the regulation of signal transduction associated molecules in responding to lipopolysaccharide （LP3） stmulation in liver cells of mice tolerant to bacterial endotoxin.Methods The experimental mice were divided into three groups randomly. In the sensitive group,mice were challenged with LPS （ 2 microgram） in combination with D-GalN. While in LPS tolerant group, mice were pretreated with a low dose LPS （0.1μg） at various time points （3h, 1d,2d,7d）, and subsequently challenged with LPS in combination with D-GalN. In the control group, mice were injected with either LPS （0.1μg）, D-GalN or normal saline. Liver cell RNA molecules and proteins were extracted,and the levels of signal transduction associated molecules were examined by RT-PCR and Western blot analysis. Results In the sensitive group, the levels of TLR-4 mRNA and protein expression were significantly increased as compared to the tolerant group （ P 〈 0.0 1 ）. The expression of IRAK-1 in the tolerant group was lower than that in the sensitive group （ P 〈 0.0 1 ）. The expression level of TRAF-6 gene was not changed by LPS pretreatment.The NF-κB （nuclear factor κB） analysis showed that the degradation of IκB in the sensitive mice was higher than that in the tolerant group. The p65 expression was lower in the tolerant group than in the sensitive group. On the contrary,expression of p50 was higher in LPS tolerant mice than in the sensitive mice. Conclusion The expression of p65 is down regulated and p50 up regulated in LPS tolerant mice,while the degradation of IκB is reduced. The down regulation of TLR4 and IRAK-1 expression may be responsible for inducing LPS tolerance in mice.

关 键 词：脂多糖 耐受 信号转导 

分 类 号：R378[医药卫生—病原生物学]