RIG-I在新生小鼠巨细胞病毒肝炎中的表达及意义

Expression and significance of RIG-Ⅰ in newborn mice with murine cytomegalovirus hepatitis

目的探讨维甲酸诱导基因I(RIG-I)在采用鼠巨细胞病毒(MCMV)诱导的新生BALB/c小鼠肝脏组织中的表达及其意义。方法 48只新生BALB/c小鼠随机分为正常对照组(NC组)和病毒组(MCMV组)各24只,MCMV组新生小鼠一次性腹腔注射MCMV20μl(TCID50:104.44/ml)方法建立肝病新生小鼠模型,NC组腹腔注射等量无菌生理盐水,分别于注射后3、7、14 d留取静脉血与肝脏组织(各8只)。PCR法检测肝脏组织中MCMV-DNA的表达,HE染色观察肝脏病理变化,RT-PCR法检测肝组织RIG-I的m RNA表达,Western blot法检测RIG-I的蛋白表达,ELISA法检测血清谷丙转氨酶(ALT)、I型干扰素IFN-β含量。结果 (1)成功建立了新生小鼠巨细胞病毒肝炎模型;(2)MCMV组小鼠肝脏组织HE染色可见明显病理损害,3 d肝细胞点状坏死,7 d大量炎性细胞浸润,片状坏死;NC组肝组织未见明显异常。(3)MCMV组ALT表达量在感染后3 d已明显升高,7 d达高峰,14 d有所下降,与对照组比较差异有统计学意义(P<0.05);RIG-I、IFN-β与ALT在3、7、14 d呈负相关(P<0.05)。结论 RIG-I参与了MCMV感染新生小鼠肝炎的发生、发展过程,肝脏中RIG-I、IFN-β表达越低肝损伤越重。推测MCMV感染后可能通过RIG-I介导的信号通路导致IFN-β分泌降低,使得MCMV在一定程度上获得免疫逃逸,成为MCMV肝炎致病机制之一。

Objective To explore the expression and significance of retinoic acid-induced gene Ⅰ（ RIG-Ⅰ） in liver of newborn mice with murine cytomegalovirus（ MCMV） hepatitis. Methods Forty-eight BALB/c newborn mice were randomly divided into control group and virus infection group（ MCMV group）,24 mice in each group,the mice in MCMV group were intraperitoneally injected with 20 μl MCMV（ TCID50： 104. 44/ml）,and the mice in control group were injected with the same dose of sterile saline. On the third day,the seventh day,and the fourteenth day after injection,eight mice in each group were sacrificed and their venous blood and liver samples were collected respectively. The expression of MCMV-DNA in liver was detected by PCR,the pathological changes of liver were observed by histological examination; RT-PCR and Western blot were used to detect the expressions of RIG-Ⅰ m RNA and protein in hepatic tissue; ELISA was used to detect the levels of serum alanine aminotransferase（ ALT） and interferon-β（ IFN-β）. Results The neonatal mice hepatitis model with MCMV infection was successfully established,and the hepatic lesions were obvious in virus infection group. Liver cells appeared point necrosis on the third day,a large number of inflammatory cells infiltration and flaky necrosis on the seventh day; there was no significant abnormalities of liver tissue in control group. The expression quantity of ALT on the third day after infection in MCMV group increased significantly,and reached the peak on the seventh day,then declined weakly on the fourteenth day,compared with control group,there were statistically significant differences（ P〈0. 05）. RIG-Ⅰ and IFN-β were negatively correlated with ALT on the third day,the seventh day,and the fourteenth day（ P〈0. 05）. Conclusion RIG-Ⅰ is involved in the occurrence and development of hepatitis of neonatal mice with MCMV infection,the lower RIG-Ⅰ and IFN-β expressions in the liver are,the heavier liver injury is. It is supposed that MCMV infection may reduce IFN-β secretion by RIG-I-mediated signaling pathway,which makes MCMV immune escape in mice,hepatitis in mice is induced.