Tetrabromobisphenol A (TBBPA) as a modulator of tryptophan catabolism and maternal-fetal health

摘要 越来越多的证据表明，接触人造化学品会扰乱人类的生殖。 健康。阐明相关机制是制定干预策略的关键。的目标是 建议的工作是研究内分泌干扰物(EDCs)在调节色氨酸中的作用 分解代谢是环境暴露导致不良妊娠结局的新机制。 色氨酸分解代谢是孕期母体免疫耐受的调节因子。未能降级 孕妇体内的色氨酸与相当大比例的人类流产、先兆子痫、 还有早产。这一过程的一个关键事件是胎盘Ido1基因的激活，该基因编码 主要色氨酸降解酶。我们的实验室已经证明，在子宫内接触到一种代表性的 EDC，四溴双酚A(TBBPA)，减少胎盘Ido1基因和蛋白的表达，并与 胎儿吸收率增加。在这项建议中，我们希望调查暴露于TBBPA是否会改变 通过干扰色氨酸分解代谢和降低母婴免疫耐受性而导致的妊娠结局。我们 会使雌性小鼠暴露于环境相关剂量的TBBPA(即，5、50和500微克/千克体重/天)之前 到交配，在交配期间，和整个怀孕期间，并分析怀孕的小鼠和胚胎。我们 希望通过分析以下几个子集来确定暴露是否与母亲免疫力下降有关 免疫抑制T细胞被称为“调节性T细胞”或“Tregs”。使用流式细胞术，我们将确定Treg 对照组和染毒孕鼠的蜕膜和子宫中的数量。色氨酸分解代谢增加 怀孕期间与母体三叉神经节的扩大有关。高高在上的母树青睐 为了维持妊娠，我们预计暴露于TBBPA的小鼠减少了Tregs。要确定是否 暴露于TBBPA的怀孕小鼠胎儿损失率增加与母体Treg减少有关 我们将使用供体Foxp3-GFP小鼠的Tregs进行过继转移研究。此外，我们 将进行基于液相色谱和质谱仪的分析，以测量色氨酸和 在妊娠的连续阶段，它在怀孕的母体、胎儿和胎盘中的分解代谢。我们希望 阐明TBBPA对母体免疫和妊娠结局的影响是否与 色氨酸分解代谢异常。最后，我们的初步研究表明，Ido1基因受 基因组印记。我们将研究TBBPA暴露对Ido1基因座印迹调控的影响 分析等位基因表达、DNA甲基化和/或组蛋白翻译后修饰 通过实时定量聚合酶链式反应、亚硫酸氢盐测序和染色质免疫沉淀。

ABSTRACT Accumulating evidence has demonstrated that exposure to man-made chemicals disrupts human reproductive health. Elucidation of the relevant mechanisms is critical for designing intervention strategies. The goal of the proposed work is to investigate the role of endocrine disrupting chemicals (EDCs) in modulating tryptophan catabolism as a novel mechanism of environmental exposure-induced adverse pregnancy outcomes. Tryptophan catabolism is a regulator of maternal immune tolerance during pregnancy. Failure to degrade tryptophan in the pregnant mother is linked to a significant proportion of human miscarriages, preeclampsia, and premature labor. A key event of this process is activation of the placental Ido1 gene that encodes for a major tryptophan-degrading enzyme. Our laboratory has shown that in utero exposure to a representative EDC, tetrabromobisphenol A (TBBPA), reduces placental Ido1 gene and protein expression, and is linked to increased rates of fetal resorption. In this proposal, we wish to investigate whether exposure to TBBPA alters pregnancy outcomes by perturbing tryptophan catabolism and reducing maternal-fetal immune tolerance. We will expose female mice to environmentally relevant doses of TBBPA (i.e., 5, 50, and 500 µg/kg bw/day) prior to mating, during mating, and throughout pregnancy, and analyze the pregnant mice and conceptuses. We wish to determine if exposures are linked to reduced maternal immunity by analyzing a subset of immunosuppressive T cells called “regulatory T cells” or “Tregs”. Using flow cytometry, we will determine Treg number in the decidua and uterus of controls and exposed pregnant mice. Increased tryptophan catabolism during pregnancy has been linked to expansion of maternal Tregs. As elevated maternal Tregs favor pregnancy maintenance, we anticipate that TBBPA-exposed mice have reduced Tregs. To determine if increased rate of fetal loss in TBBPA-exposed pregnant mice is causatively linked to reduced maternal Treg number, we will perform an adoptive transfer study using Tregs from donor Foxp3-GFP mice. Additionally, we will perform liquid chromatography and mass spectrometry-based assays to measure levels of tryptophan and its catabolites in the pregnant dam, fetus, and placenta during sequential stages of pregnancy. We wish to elucidate whether TBBPA-induced effects on maternal immunity and pregnancy outcomes are linked to abnormal levels of tryptophan catabolites. Finally, our preliminary studies show that the Ido1 gene is subject to genomic imprinting. We will investigate effects of TBBPA exposure on imprinting regulation of the Ido1 locus by analyzing allele-specific gene expression, DNA methylation and/or posttranslational histone modifications through quantitative real time PCR, bisulfite sequencing, and chromatin immunoprecipitation.