IUGR蒙古绵羊胎儿胸腺微环境程序性改变及其阻滞胸腺T淋巴细胞发育分子机理研究

Intrauterine growth restriction (IUGR) caused by maternal undernutrition is a relatively common condition, which severely restrict the growth of fetal thymus, induce programming modifications of fetal thymic microenvironment, and result in retardation of intrathymic T lymphocyte development and deficiency of cellular immunity. However, the mechanisms remain unclear. Therefore, this study intends to analyze the effects of IUGR on growth and development of fetal thymus, thymic structure and the programming modifications of Mongolian ovine fetal thymic microenvironment, measure the concentrations of extracellular growth factors, the gene expressions and epigenetic modifications of their receptors in IUGR ovine fetal thymus, determine main cell signaling pathways manipulating the programming modifications of ovine fetal thymic microenvironment and their relationships, investigate the retarding mechanisms of the main cell signaling pathways in programming modifications IUGR fetal thymic microenvironment to the development and differentiation of intrathymic T lymphocyte, in order to reveal the trinity molecular signal network of extracellular growth factors and their receptors - Regulating signaling pathways in programming modifications of fetal thymic microenvironment - Intrathymic T lymphocyte development, and clarify molecular mechanisms underlying the programming modifications of thymic microenvironment and retardation of intrathymic T lymphocyte development in IUGR Mongolian ovine fetuses, supply references for scientific feeding and management during the winter-spring grazing season of north China as well as the researches correlated in medical science.

母体营养缺乏导致的胎儿宫内生长受限（IUGR）是一种普遍现象，它严重阻滞胎儿胸腺生长发育并引发胸腺微环境的程序性改变而导致胸腺T淋巴细胞发育分化受阻、细胞免疫缺陷，但机理仍不很清楚。因此，本项目拟通过分析IUGR影响绵羊胎儿胸腺生长发育、组织结构及胸腺微环境程序性改变的一般规律，测定IUGR胎儿胸腺细胞外生长因子及其受体表达和表观遗传修饰变化，明确IUGR调控胎儿胸腺微环境程序性改变主效信号通路及其相互关系，研究IUGR胎儿胸腺微环境程序性改变主效信号通路调控T淋巴细胞发育分化机理，从器官、细胞和分子的不同层次系统揭示IUGR绵羊胎儿胸腺细胞外生长因子及其受体-胸腺微环境程序性改变信号通路-T淋巴细胞发育三位一体的分子调控信号网络，阐明IUGR绵羊胎儿胸腺微环境程序性改变及其阻滞T淋巴细胞发育分子机理，为建立北方草原地区冬春季节合理科学的饲养管理制度及医学相关研究提供一定的参考依据。

妊娠期母体营养缺乏引发的胎儿宫内生长受限严重阻滞胎儿胸腺生长发育并引发胸腺微环境的程序性改变而导致胸腺T 淋巴细胞发育分化受阻、细胞免疫缺陷，但机理仍不清楚。因此，本项目开展了IUGR 绵羊胎儿胸腺微环境程序性改变及其阻滞T 淋巴细胞发育分子机理研究。结果表明：RG1组（P<0.01）、RG2（P<0.05）胎儿胸腺重、总DNA含量显著降低，而RG1组G1期细胞数显著升高（P<0.05）。随着母体营养水平的降低，RG1、RG2组胎儿胸腺K8降低（P<0.01）；RG1组胎儿胸腺中Ⅰ型胶原含量、纤连蛋白含量、前胸腺素а、胸腺肽β4、CXCL10、CXC12、 CXC25、β2微球蛋白、ICAM-1、P选择素、TNF-α、IL-1β、IL-4均显著低于CG组（P<0.05），而羟脯氨酸、层粘连蛋白、胸腺生成素显著高于CG组（P<0.05）；对于RG2组，胎儿胸腺纤连蛋白、CXCL10、TNF-α和IL-1β显著降低（P<0.05）。进一步对生长因子研究发现：RG2和RG1组胎儿血中GH浓度、GHR受体基因和蛋白、胸腺中PDGF、EGFR、VEGFR、NGFR均显著低于CG组（P<0.05），而且RG1组胎儿血中IGF-1和IGF-2浓度、胸腺中IGF-1R受体基因和蛋白、IGF-2R受体基因和蛋白均低于CG组（P <0.05）。转录组结果表明：生长因子介导各组胎儿胸腺细胞增殖及微环境程序性改变的细胞内信号通路主要富集在ECM-receptors interaction、MAKP Sigaling pathway、PI3K-Akt Sigaling pathway、TGF-β Sigaling pathway、Cell cycle、Pathways in cancer等。对T细胞发育分化调控关键基因研究发现：RG1、RG2组胎儿胸腺中ITK、ThPOK 基因表达降低（P <0.05），且RG1 组Gata3显著高于CG组（P <0.05）。这些结果一定程度揭示了IUGR 导致绵羊胎儿胸腺微环境程序性改变及其阻滞T 淋巴细胞发育分子机理，为建立北方草原地区冬春季节合理科学的饲养管理制度以及医学该领域的研究提供一定的参考依据。