Determining the Role of Atrazine and Atrazine-Induced Estrogen in Increasing CD4+

描述（由申请人提供）：莠去津是美国最广泛使用的除草剂之一。由于农作物施用后的农业径流，它是美国最常见的地下水污染物 ​​(://water.usgs.gov/nawqa/)。阿特拉津被归类为内分泌干扰化合物，因为它能诱导 CYP19（芳香酶），其催化活性会导致雌激素产生增加。虽然已经进行了大量研究来探讨与莠去津暴露相关的潜在健康风险，但大多数研究都集中在与雌激素升高相关的生殖异常上。少数研究检查了莠去津对哺乳动物免疫系统的影响，但对免疫系统的影响仍然很大程度上未知。之前的研究都没有关注免疫细胞的关键子集 CD4 T 辅助细胞的激活和功能。这些细胞有助于形成针对病原体和癌症的保护性免疫反应，并维持自我耐受性。 CD4 T 细胞数量或效应子活性的扰动可能会对个体的健康产生可怕的后果。例如，调节性 T 细胞 (Treg) 的增加可能导致免疫抑制，并导致感染或癌症的易感性增加。初步体外研究发现，阿特拉津暴露显着抑制传统 T 细胞的增殖、活化和细胞因子产生。此外，在阿特拉津暴露的细胞中，Foxp3 Treg 的频率显着增加。在本提案中，我们将研究莠去津介导的 CD4 T 细胞抑制机制。该提议的假设是莠去津会增加雌激素水平，从而通过直接抑制这些细胞和诱导 Treg 细胞显着增加来抑制 CD4 T 细胞的活化。它将使用 2 个具体目标进行测试：第一个目标是在体外和体内检查莠去津诱导的 Treg 频率的机制。使用来自 Foxp3gfp OT-II 小鼠的 TCR 转基因 T 细胞，我们将确定莠去津是否诱导 nTreg 扩增或常规 T 细胞向诱导性 Treg (iTreg) 细胞的转化。我们还将研究在缺乏 Treg 的情况下，阿特拉津暴露对传统 T 细胞表型的直接影响。在第二个目标中，将使用药物抑制剂和抗体阻断相结合，检查莠去津介导的雌激素产生对 Treg 增加的作用。

DESCRIPTION (provided by applicant): Atrazine is one of the most widely used herbicide in the United States. As a result of agricultural runoff after crop applications, it is the most commo ground water contaminant in the US (://water.usgs.gov/nawqa/). Atrazine is classified as an Endocrine-Disrupting Compound due its induction of CYP19 (aromatase), whose catalytic activity leads to increased estrogen production. While a significant amount of research has been done looking into the potential health risks associated with atrazine exposure, most have focused on reproduction abnormalities related to elevated estrogen. A small number of studies have examined the effect of atrazine on the mammalian immune system, but the effects on the immune system remain largely unknown. None of the previous studies have focused on the activation and functions of a critical subset of immune cells, the CD4+ T helper cells. These cells help shape the protective immune response to pathogens and cancer as well as maintaining tolerance of self. Perturbations of CD4+ T cell numbers or effector activity can have dire consequences for the health of the individual. For example, an increase in regulatory T cells (Treg), can lead to immune suppression and resulting in increased susceptibility to infection or cancer. In preliminary in vitro studies, it was observed that atrazine exposure significantly inhibits the proliferation, activation and cytokine production by conventional T cells. Further, there is a significant increase in the frequency of Foxp3+ Treg in atrazine-exposed cells. In this proposal we will examine the mechanism of atrazine-mediated inhibition of CD4+ T cells. The hypothesis of this proposal is that atrazine increases estrogen levels which suppresses CD4+ T cell activation by both directly inhibiting these cells and by inducing a significant increase of Treg cells. It will be tested using 2 specific aims: In the first aim, the mechanism of atrazine-induced Treg frequency will be examined in vitro and in vivo. Using TCR transgenic T cells from Foxp3gfp+ OT-II mice, we will determine whether atrazine is inducing expansion of nTreg or conversion of conventional T cells to induced Treg (iTreg) cells. We will also examine the direct effects of atrazine exposure on the phenotype of conventional T cells in the absence of Treg. In the second aim, using a combination of pharmacological inhibitors and antibody blockade, the role of atrazine-mediated estrogen production on the Treg increase will be examined.