早孕期弓形虫感染对大鼠胎盘RT.BM1及RT1-E基因转录的影响

通过检测正常妊娠和早孕期弓形虫感染的Wister大鼠胎盘RT.BM1和RT1-E mRNA的表达水平,发现二者在正常妊娠中的规律,进而探索早孕期弓形虫感染对胎盘RT.BM1和RT1-E mRNA表达的影响,以阐明弓形虫感染致不良妊娠结局的分子免疫机制。将48只孕鼠随机分为感染组和正常组,每组24只。感染组于妊娠第5天腹腔注射1×105个弓形虫强毒株(RH株)速殖子/只,正常组不作任何处理。两组于孕第9、13、15、17天分别处死6只孕鼠,无菌剖腹,观察胎鼠情况,计数死胎及活胎数。采用实时荧光定量聚合酶链式反应(real-time PCR)检测胎盘RT.BM1和RT1-E mRNA表达水平。结果:①正常组活胎数204只,死胎3只,死胎率1.4%,感染组活胎数133只,死胎27只,死胎率16.9%,死胎率明显高于正常组(P<0.05);②正常组RT.BM1 mRNA在孕第9、13、15、17天的相对表达水平为(3.21±1.32)、(4.35±1.29)、(3.96±1.49)、(11.1±2.15),前三个时间点表达水平基本一致(P>0.05),第17天则明显增高(P<0.01);RT1-E mRNA在各时间点相对表达水平为(0.79±0.45)、(2.15±1.03)、(2.13±1.74)、(2.39±1.85),第9天明显低于后三个时间点(P<0.05);③感染组各时间点RT.BM1 mRNA相对表达水平为(12.4±2.86)、(11.5±3.67)、(6.89±1.59)、(17.3±3.06),第9、13、15天与正常组相比有显著差异(P<0.01);而RT1-E mRNA分别为(1.83±0.886)、(4.72±1.59)、(4.24±2.26)、(3.83±2.26),第9、13、15天与正常组相比均有显著差异(P<0.01)、(P<0.05)、(P<0.01)。结果显示弓形虫感染量合适,动物模型成功建立;RT.BM1和RT1-E mRNA在大鼠胎盘的表达水平与妊娠进展密切相关;大鼠早孕期弓形虫感染可致胎盘局部RT.BM1和RT1-E表达增高,从而打破正常妊娠所需的胎盘局部免疫平衡状态,可能是早孕期弓形虫感染致不良妊娠结局的分子机制之一。

Effect of infection with Toxoplasma gondii during early pregnancy on the transcription of RT.BM1 and RT1-E genes in rat placenta

To investigate the expression of RT.BM1 and RT1-E mRNA on normal rat placenta and their changes infected with Toxoplasma gondii during early gestation and in order to explore the molecular immunological mechanism in abnormal pregnancy induced by T.gondii infection.48 pregnant Wistar rats were randomly divided into two groups equally.The infection group was intraperitoneally injecued with 1×105 of living T.gondii RH strian tachyzoites on the 5th day of gestation,and the normal group of rats were not given any injection.Six rats were euthanized at days 9,13,15 and 17 respectively.Placentas were collected and the expression of RT.BM1 and RT1-E mRNA were analyzed by real-time quantitative PCR.It was demonstrated that: ①The number of living embryo of normal group was 204,and the number of death embryos and absorption embryos was 3,then the stillborn rate was 1.4%.But the infection group was 133,27,16.9% respectively and the stillborn rate was significantly higher than that of normal group(P<0.05);②The relative expression levels of RT.BM1 mRNA in the normal group at 9,13,15,17 day were(3.21±1.32),(4.35±1.29),(3.96±1.49),(11.1±2.15) respectively.There are no significant difference of expression level among 9th,13th day and 15th day(P>0.05).But it significantly increased at 17th day(P<0.01).The average mRNA expression of RT1-E of normal group were(0.79±0.45),(2.15±1.03),(2.13±1.74),(2.39±1.85) respectively and it was lowest at 9th day(P<0.05);③The relative expression levels of RT.BM1 mRNA in the infection group was(12.4±2.86),(11.5±3.67),(6.89±1.59),(17.3±3.06) at the four time points and significantly higher than that of the normal group at 9th,13th,15th day(P<0.01);The average mRNA expression of RT1-E of infected group were(1.83±0.886),(4.72±1.59),(4.24±2.26),(3.83±2.26) respectively and significantly higher than that of the normal group at 9th,13th,15th(P<0.01,P<0.05,P<0.01).It is concluded that the rat model was successfully established;the normal expression of RT.BM1 and RT1-E in rat placenta is essential during the pregnancy and abnormal pregnancy was induced by infection with T.gondii due to expression level of RT.BM1 and RT1-E in rat placenta upregulated.This molecular immunological mechanism may play an important role in abnormal pregnancy infected with T.gondii during the early pregnancy.