IL-1β和IL-18在鼠巨细胞病毒播散性感染中的表达及意义

The expressions of IL-1β and IL-18 in mice with disseminated murine cytomegalovirus infection

目的:在整体水平观察鼠巨细胞病毒(Murine cytomegalovirus,MCMV)播散性感染时脏器病毒载量、caspase-1的活化及其下游因子IL-1β和IL-18的表达状况。方法:建立MCMV播散性感染模型,MCMV Smith株接种后第0、3、7和14天各处死4只小鼠;同时设模拟感染小鼠作为对照。标准空斑试验检测唾液腺、肺和肝组织病毒滴度;Western blot法检测脾细胞中procaspase-1及其活化形式caspase-1的表达强度;双抗体夹心ELISA法检测血清IL-1β和IL-18水平;免疫组化法检测唾液腺、肺和肝组织中IL-1β和IL-18表达状况。结果:肝组织病毒滴度于MCMV感染后3天升高,其后迅速减低,感染2周内肺组织中未检测到病毒,而唾液腺组织病毒滴度呈逐渐增高趋势;与模拟感染对照组比较,播散性感染组感染后3天脾细胞中procaspase-1和caspase-1的表达明显升高(相对吸光值均P<0.01);同时,血清IL-1β和IL-18水平升高达峰值(均P<0.01)。结论:MCMV感染后炎性体活化,caspase-1表达升高;其下游信号IL-1β和IL-18成熟释放增加,并呈组织差异性表达。

Objective：To investigate the expressions of IL-1β and IL-18 in mice with disseminated murine cytomegalovirus（MCMV） infection,this study characterized the expression of caspase-1,and the distribution of IL-1β and IL-18 in different organs.Methods：BALB/c mice were randomly divided into two groups.One was infected with MCMV Smith for establishing disseminated infection;the other was sham-inoculated control.On days 0（representing uninfected control mice）,3,7,14 of the experiment,four mice of each group were randomly chosen to be killed separately.The viral titers in tissues of salivary gland,lung and liver were quantified by a standard plaque assay.The expressions of procaspase-1 and caspase-1 were detected by Western blot.The levels of IL-1β and IL-18 in sera were measured by double antibody sandwich ELISA,and their expressions in different organs were detected by immunohistochemistry.Results：MCMV titers in livers quickly increased to peak levels on day 3 after infection but quickly declined.Titers in the lung were undetectable throughout the two weeks.In the salivary gland,viral titers gradually increased after infection.The expressions of procaspase-1 and caspase-1 in spleen were significantly increased and peaked on day 3 but gradually decreased afterwards.Meanwhile,the levels of IL-1β and IL-18 in sera of MCMV-infected mice were significantly higher than those in controls（all P0.01）.Conclusion：These results demonstrate that the inflammasome has been actived and converted procaspase-1 to caspase-1,and the levels of IL-1β and IL-18 in sera are significantly increased and the cytokines display organ-specific distribution after MCMV infection.