Genetic and epigenetic contributions to the neonatal Th2 bias

描述（由申请人提供）：新生儿的免疫反应通常由抗炎Th2细胞因子的显性产生来定义，这种情况被称为新生儿Th2偏倚。这种细胞因子分泌模式被认为有助于幼龄动物对感染的易感性和th2介导的疾病（如哮喘）的发展。因此，旺盛的Th2功能是早期免疫的关键特征。了解这是如何产生的对于我们理解适应性免疫系统的个体发生是至关重要的。新生儿的Th2偏倚反应部分是由于快速、高水平的Th2细胞因子产生。我们已经证明Th2细胞因子IL-4和IL-13都是由新激活的小鼠新生儿CD4+细胞早期和大量产生的。在成人Th2细胞中，高水平Th2细胞因子的协调表达需要一个称为保守非编码区1 （CNS-1）的基因间调控区。因此，CNS-1遗传因子可能对新生儿早期强劲的Th2细胞因子产生有重要作用。事实上，该DNA元件在个体发育早期以一种相对宽松的表观遗传状态存在。我们发现，与幼稚成人细胞不同，在幼稚胎儿和新生儿T系细胞中，CNS-1在CpG残基处低甲基化。这种低甲基化状态与新生儿CD4+细胞快速、高水平的Th2细胞因子产生密切相关。CNS-1的甲基化在出生后迅速发生，在出生后第一周结束时达到成人甲基化水平。随着发育的增加，CNS-1甲基化的增加与Th2细胞因子基因快速表达的逐渐沉默有关。总之，这些观察结果表明，CNS-1可能在确定新生儿Th2偏倚中起着重要的中心作用。我们的长期目标是了解遗传和表观遗传对早期生命中Th2显性状态的贡献。在本研究中，我们将重点研究Th2细胞因子基因座中定义明确的CNS-1区域。我们的初步数据引出了两个明确的假设。特异性目标1将测试CNS-1区域的物理存在是实现新生儿Th2细胞因子过量生产所必需的。这将通过比较野生型和cns -1缺陷新生儿中Th2位点的表观遗传状态和Th2细胞因子的产生来实现。特异性目标2将检查胎儿和新生儿生命中CNS-1的低甲基化是产生新生儿Th2偏倚的必要前提。这将通过制造转基因小鼠来测试

DESCRIPTION (provided by applicant): Immune responses in neonates are often defined by dominant production of anti-inflammatory Th2 cytokines, a condition referred to as the neonatal Th2 bias. This pattern of cytokine secretion is thought to contribute to the susceptibility of young animals to infection and to the development of Th2-mediated diseases, such as asthma. Thus, vigorous Th2 function is a key defining feature of immunity in early life. Learning how this arises is of central importance for our understanding of the ontogeny of the adaptive immune system. The Th2 biased responses of neonates are due, in part, to rapid, high-level Th2 cytokine production. We have demonstrated that the Th2 cytokines IL-4 and IL-13 are both produced early and in copious amounts by newly activated murine neonatal CD4+ cells. In adult Th2 cells, coordinate expression of high levels of Th2 cytokines requires an intergenic regulatory region called conserved non-coding region 1 (CNS-1). Therefore, the CNS-1 genetic element may contribute importantly to the early, robust Th2 cytokine production in neonates. Indeed, this DNA element exists in a relatively permissive epigenetic state in early ontogeny. We have found that, unlike in naive adult cells, CNS-1 is hypomethylated at CpG residues in naive fetal and neonatal T lineage cells. This hypomethylated state is strongly linked to rapid, high level Th2 cytokine production by neonatal CD4+ cells. Methylation of CNS-1 occurs rapidly post birth, with adult levels of methylation being attained by the end of the first week o life. Increasing methylation of CNS-1 with increasing development is associated with the progressive silencing of rapid Th2 cytokine gene expression. Together, these observations indicate that CNS-1 may play a centrally important role in defining the neonatal Th2 bias. Our long-term goals are to understand the genetic and epigenetic contributions to the Th2 dominant state of early life. In this proposal, we will focus on the well-defined CNS-1 region in the Th2 cytokine locus. Our preliminary data lead to two clear hypotheses. Specific Aim 1 will test the idea that the physical presence of the CNS-1 region is required to achieve Th2 cytokine overproduction in neonates. This will be achieved by comparing the epigenetic state of the Th2 locus and Th2 cytokine production in wild-type and CNS-1-deficient neonates. Specific Aim 2 will examine the premise that hypomethylation of CNS-1 in fetal and neonatal life is essential for generating the neonatal Th2 bias. This will be tested by creating transgenic mice with forced methylation of CNS-1 throughout development. Constructs containing a CNS-1-targeted zinc finger protein coupled to the catalytic domain of the de novo DNA methyltransferase Dnmt3a will be created~ expression of the constructs will be confined to T lineage cells. The epigenetic state of the Th2 locus and Th2 function will be assessed in the transgenic mice. These studies will be the first to dissect genetic and epigenetic regulation at the Th2 cytokine locus in early ontogeny. Results from these studies will ultimately lead to interventional strategies aimed at improving pediatric health by mitigating the Th2 dominant state in early life.