调节性T细胞Foxp3下调在弓形虫排泄分泌抗原致流产中的作用及其机制的研究

CD4+CD25+ regulatory T cells were involved in the systemic regulatory processes and claimed to be important players in the tolerance towards the fetus bearing alloantigens in pregnancy. Recent evidence confirmed that the diminished numbers of CD4+CD25+regulatory T cells were associated with the abortion induced by the infection of Toxoplasma gondii. Although the function of CD4+CD25+ regulatory T cells is regulated by Foxp3, the details of the molecular mechanism responsible for the diminished expression of Foxp3 induced by Toxoplasma gondii are poorly understood. In our previous study, the excreted-secreted antigens of Toxoplasma gondii could inhibit the expression of Foxp3. To define the mechanism of the diminished expression of Foxp3 induced by Toxoplasma gondii, a model of the excreted-secreted antigens of Toxoplasma gondii-induced abortion and mifepristone (RU 486)-induced medical abortion in mice, CD4+CD25+regulatory T cell lines(EL4 cell lines) will be utilized. We will probe into the mechanism of the down regulation of Foxp3 caused by Toxoplasma gondii in the Smad2/ Smad3/ Foxp3 signal transduction pathway by Real-time PCR, Western blot, Immunofluorescence, Flow cytometry, RNA interference and so on. Expected outcomes will provide the essential theoretical basis on the abortion caused by Toxoplasma gondii or other factors.

CD4+CD25+调节性T细胞参与全身性免疫调节，有助于妊娠期间免疫耐受的形成。有研究表明弓形虫感染所致的流产与调节性T细胞下调相关。Foxp3作为调节性T细胞重要的功能分子，弓形虫感染如何抑制Foxp3的表达，尚未见报道。我们前期试验观察到弓形虫排泄分泌抗原可抑制Foxp3的表达，为了探索弓形虫排泄分泌抗原抑制Foxp3表达机制，本课题将运用弓形虫排泄分泌抗原促流产模型，RU486促流产小鼠模型及调节性T细胞株（EL4细胞株），通过Real-time PCR、Western blot、免疫荧光、流式细胞术、RNA 干扰等技术深入研究排泄分泌抗原抑制Foxp3表达的作用从而下调调节性T细胞功能的作用机制，揭示Smad2/ Smad3/ Foxp3信号通路在流产中作用机制。预期结果将为弓形虫感染促流产乃至整个流产的机制研究提供新的理论基础。

CD4+CD25+调节性T细胞参与全身性免疫调节，有助于妊娠期间免疫耐受的形成。有研究表明弓形虫感染所致的流产与调节性T细胞下调相关。Foxp3作为调节性T细胞重要的功能分子，弓形虫感染如何抑制Foxp3的表达，尚未见报道。因此，为了探索弓形虫排泄分泌抗原抑制Foxp3表达机制，我们运用弓形虫排泄分泌抗原促流产模型，RU486促流产小鼠模型及调节性T细胞株（EL4细胞株），深入研究排泄分泌抗原抑制Foxp3表达的作用从而下调调节性T细胞功能的作用机制。结果表明，弓形虫排泄分泌抗原在体内能诱导调节性T细胞数量下调，母胎界面Foxp3表达下降，调节性T细胞抑制功能受到抑制。在体外，弓形虫排泄分泌抗原诱导EL4细胞Foxp3表达下降，同时，抑制磷酸化的Smad2，磷酸化的Smad3及 Smad4的表达。同时，我们的研究也表明，弓形虫排泄分泌抗原通过抑制TGF-β受体II,阻断Smad2/Smad3/Smad4/Foxp3信号通路，从而抑制Foxp3表达。这些结题提示，CD4+CD25+调节性T细胞是弓形虫感染促流产的重要的靶细胞，其功能状态决定妊娠的状态。