摘要
目的定量检测巨细胞病毒(murine cytomegalovirus,MCMV)感染小鼠脾细胞调节性T细胞(Treg)、辅助性T细胞1型和2型(Th1/Th2)特异性转录因子Foxp3、T-bet和GATA-3mRNA水平的动态变化,探讨MCMV在急慢性感染期对Treg、Th1和Th2细胞分化增殖的影响及其意义。方法建立MCMV全身播散型感染模型,根据主要脏器内病毒滴度,确定感染后28d为本模型急、慢性期界定点。42只模型鼠分别于接种病毒后第1、3、7、14、28、45、60天各处死6只小鼠,分离脾细胞,以灭活MCMV抗原为刺激原,体外培养5d,另设42只正常小鼠作为模拟感染对照。用Real-timeRT-PCR法检测小鼠脾细胞Foxp3、T-bet和GATA-3mRNA表达强度。结果MCMV感染组第7天T-betmRNA表达显著增高达峰值,与模拟感染对照组比较差异有统计学意义(P<0.01),随后下降,到第28天降到对照组相当水平,至第60天显著低于对照组(P<0.01);而GATA-3mRNA在感染后第3天表达开始升高,第7天达峰值,第14天开始缓慢下降,但至第60天仍显著高于对照组(P<0.05);Foxp3mRNA表达在感染后14天明显低于对照组,第28天显著降低(P<0.01),但至第45天开始明显上调,第60天升高更显著(P<0.01)。结论在感染急性期,Treg未被诱导活化,宿主产生有效Th1/Th2应答反应,但随后逐渐下降,并向Th2偏移;在感染慢性期,Treg细胞增殖活化显著,进一步抑制Th1和Th2反应,且对Th1抑制效应更强,提示CMV诱导Treg细胞增殖活化是其抑制宿主抗病毒免疫而呈持续慢性感染的重要原因。
Objectives To quantitate the expression kinetics of specific transcription factor Foxp3, T-bet and GA-TA-3 genes expression in regulatory T cells （Tregs）, helper T cells type 1 （Th1） and type 2 （Th2） in mice infected by murine cytomegalovirus （MCMV）. To study the effect of MCMV on the proliferation of Tregs, Th1 and Th2 cells in the acute and chronic phase of infection. Methods Disseminated MCMV infection was established in BALB/c mouse model. Based on the viral titer in major visceral organs, Day 28 post-infection was used as the differential point for acute and chronic infection. Forty two experimental mice in the MCMV infected group （n = 6 at each time point） were sacrificed on Day 1, 3, 7, 14, 28, 45 and 60 after MCMV infection. The spleen cells were isolated and cultured for 5 days in vitro using inactivated MCMV as stimulants. Another 42 mock infected mice were included as controls. Real-time RT-PCR was used to quantitate the mRNA expression of Foxp3, GATA-3 and T-bet in spleen cells. Results The level of T-bet mRNA peaked on Day 7 after infection, which was significantly higher than that of mocked-infected controls （P 〈 0.01）, and then decreased to the level similar to the controls on Day 28, and afterwards kept decreasing from Day 45 to Day 60, which was significantly lower than that of the controls （P 〈 0.01 ） . The level of GATA-3 mRNA increased on Day 3 and peaked on Day 7, and then gradually decreased from Day 14 to Day 60, but still higher than that of the controls. The level of Foxp3 mRNA significantly decreased from Day 14 to Day 28, but was dramatically up-regnlated on Day 45 and markly Day 60 （P 〈 0.01 ）. Conclusions In the acute phase of MCMV infection, Tregs were not activated. The host pro-duced effective Th1 and Th2 immune responses which gradually decreased and shifted to Th2 dominance. During the chronic phase, MCMV could induce significant proliferation and activation of Tregs, which further suppressed the Th 1 and Th2 responses. The suppression is stronger in Th 1 than Th2 cells. It is suggested that proliferation and activation of Treg cells induced by MCMV is an important cause for suppressed host antiviral immunity and persistent chronic CMV infection in host.
出处
《临床儿科杂志》
CAS
CSCD
北大核心
2007年第7期537-540,546,共5页
Journal of Clinical Pediatrics
基金
国家自然科学基金资助项目(No.30572345)
作者简介
通讯作者：方峰电子信箱：ffang@tjh．tjmu
