Background Macrophage migration inhibitory factor （MIF） is an upstream regulator in immune and inflammatory responses.However,its role in viral myocarditis remains unknown.In this study,we investigated the role of the MIF in coxsackievirus B3 （CVB3）-induced myocarditis.Methods Mice were randomized into two groups receiving either Eagle＇s minimal essential medium （EMEM,control group） or virus solution （infected group）.Subsets of mice in the infected group were sacrificed on days 3,7,14 and 28 after inoculation.Expression of MIF was detected using an enzyme-linked immunosorbent assay （ELISA）,reverse transcription polymerase chain reaction and immunohistochemistry.A neutralizing antibody （Ab） to MIF was injected intraperitoneally from day 0 to 7 after inoculation.Disease severity was estimated by histopathology of the heart and by the heart weight to body weight ratio,and the interleukin-1β （IL-1β） and tumor necrosis factor α （TNF-α） in the myocardium were measured by ELISA on day 14.Results The serum MIF concentration and expression levels of myocardial MIF mRNA and protein were significantly elevated in mice on days 7 and 14 post-infection.The survival rate was markedly higher and disease severity was obviously less in mice treated with anti-MIF Ab.Furthermore,MIF blockade significantly decreased the IL-1β and TNF-α in the myocarditic heart.Conclusion These results demonstrate that MIF is an important naturally occurring inflammatory cytokine in CVB3-induced myocarditis,and anti-MIF Ab may lessen the inflammatory response.
目的:观察黄芪甲甙干预的病毒性心肌炎(viral myocarditis,VMC)小鼠中TL1A表达的影响,探讨黄芪甲甙治疗VMC的作用机制。方法:取Balb/c小鼠100只,随机分成6组。非感染小鼠腹腔无菌注射不含病毒的Eagle’s培养液0.1 m L,分为正常对照组10只,以羧甲基纤维素钠0.1 m L灌胃7 d;高剂量对照组10只,9%黄芪甲甙0.1 m L灌胃7 d;余80只小鼠以腹腔无菌注射0.1 m L内含1×102 5 0%组织感染率(TCID50)柯萨奇病毒B3(Cox sachiev ir us B3,CVB3)的Eagle’s培养液制作VMC模型。VMC小鼠随机分为心肌炎对照组和低、中、高剂量干预组,分别以生理盐水和1%,3%,9%黄芪甲甙[分别为0.07,0.2,0.6 g/(kg.d)]0.1 m L灌胃7 d(每组20只)。14 d后处死全部小鼠并取其心脏。采用RT-PCR及免疫组织化学分别检测心肌TL1A m RNA及蛋白表达水平。结果:正常对照组和高剂量对照组无小鼠死亡,心肌炎对照组有大量小鼠死亡,死亡率为45%(9/20),低、中、高剂量干预组小鼠死亡率分别为30%(6/20),25%(5/20),10%(2/20),高剂量干预组小鼠死亡率较心肌炎对照组明显降低(P<0.05),而低、中剂量干预组小鼠死亡率与心肌炎对照组比较,差异无统计学意义(P>0.05);正常对照组和高剂量对照组心肌未见任何病理改变,然而两组心肌中均有一定量的TL1A mRNA及蛋白表达,两组比较差异无统计学意义(P>0.05),心肌炎对照组TL1A mRNA及蛋白表达水平明显增加,与正常对照组比较,差异有统计学意义(P<0.01),心肌炎小鼠经不同剂量黄芪甲甙干预后,与对照组相比,在高剂量干预组显著下降(P<0.01),而低、中剂量黄芪甲甙对心肌炎小鼠TL1A mRNA、蛋白表达水平以及心肌病变积分无明显影响(P>0.05)。结论:黄芪甲甙治疗VMC可能通过抑制炎症介质、降低TL1A的表达而起作用。
