Maternal programming of the stem cell-basophil axis for asthma

项目摘要/摘要 越来越多的流行病学研究将儿童哮喘与母亲的环境暴露联系起来 为柴油废气和香烟烟雾提供了最有力的证据。母体接触如何导致 后代中的哮喘是未知的。为了解决这个问题，我们开发了一种幼鼠哮喘易感性的小鼠模型。 通过让它们的母亲暴露在柴油废气颗粒物(DEP)中。我们的数据表明，在这个由环保部驱动的模型中， 哮喘易感信息部分通过子代长期造血干细胞亚群传递 干细胞(LT-HSCs)，以干细胞记忆的形式。这个子集通过IL3的表达来区分自己 受体被编程为通过DEP诱导的协同作用促进嗜碱性粒细胞的产生 IL-1b和IL-3。IL1b和IL3之间协同作用的一个关键机制是IL1b增加 干细胞对IL-3的敏感性部分是由于IL-1b介导的IL-3R b链上调。除了……之外 扩大嗜碱性粒细胞谱系，IL3和IL1b可能会增强其促进哮喘的能力。上一首 研究表明，IL1b增强嗜碱性粒细胞组胺的释放，IL3有力地刺激其IL4的产生。 为第二型免疫反应播下种子。与此一致的是，在DEP后代中，嗜碱性粒细胞过度表达 IL-4。IL3/IL1b启动的、扩大的、IL4过表达的嗜碱性粒细胞群体成为该类型的关键驱动因素。 2变应原激发时的免疫反应和哮喘。DEP幼鼠的嗜碱性粒细胞耗尽阻止了后代的产生 过敏原特异性免疫球蛋白E与哮喘的发生。这与在普通过敏原中获得的数据形成了对比- 基于嗜碱性粒细胞多余产生IgE和哮喘的模型。我们最重要的假设 母亲接触DEP是否通过IL1b和IL3驱动导致子代哮喘易感性 造血干细胞-嗜碱性粒细胞轴的编程。在目标1中，通过进行干细胞移植 实验中，我们将建立DEP IL3R+LT-HSCs之间的联系，增加碱基生成与易感性 哮喘。我们将通过分析它们的转录本来定义DEP IL3R+LT-HSC编程的分子基础 (RNA-seq)和基因调控位点的染色质重塑(atac-seq)。在目标2中，我们将研究重要性 IL-1b和IL-3在诱导哮喘的HSC-嗜碱性粒细胞轴编程中的作用在我们的模型中，IL1b和IL3是 在子代和母体组织中增加，包括母体血清。我们认为母体IL-1b和IL-3 在胚胎造血的早期阶段很重要，当HSCs经历它们的初始分裂和 IL-1b和IL-3的胚胎来源很少。子代衍生的IL1b和IL3完成HSC编程 在母体细胞因子消退后，维持高水平的碱性造血过程，并有助于碱性粒细胞的激活 离开。为了确定母体IL1b和IL3是如何转移到胚胎中的，研究它们在后代中的角色和作用- 编码IL1b和IL3，我们将进行血清转移，注射放射性标记的细胞因子，并结合 使用胚胎移植的IL1b或IL3KO策略。在目标3中，我们将使用人类血液样本来研究IL1b和 IL-3在儿童哮喘中引导嗜碱粒细胞发育。

Project Summary/Abstract A growing number of epidemiological studies link childhood asthma with maternal environmental exposures with the strongest evidence provided for diesel exhaust and cigarette smoke. How maternal exposures lead to asthma in offspring is unknown. To address this, we developed a mouse model of asthma susceptibility in pups by exposing their mothers to diesel exhaust particles (DEP). Our data suggests that in this DEP-driven model, asthma-predisposing information is transmitted in part by a subset of offspring long-term hematopoietic stem cells (LT-HSCs), in the form of a stem cell memory. This subset distinguishes itself by expression of the IL3 receptor and is programmed for enhanced generation of basophils by the synergistic action of DEP-induced IL1b and IL3. One key mechanism of the synergism between IL1b and IL3 is the ability of IL1b to increase stem cell sensitivity to IL3 which is in part due to IL1b-mediated upregulation of IL3R b chain. In addition to expanding the basophil lineage, IL3 and IL1b are likely to enhance its capacity to promote asthma. Previous studies show that IL1b potentiates basophil histamine release and IL3 potently stimulates their IL4 production, sowing the seed for type-2 immune response. Consistent with this, in DEP offspring, basophils overexpress IL4. The IL3/IL1b-primed, expanded, IL4-overexpressing basophil population becomes a key driver of the type- 2 immune response and asthma upon allergen challenge. Basophil depletion in DEP pups prevents generation of allergen-specific IgE and development of asthma. This is in contrast with data obtained in plain allergen- based models in which basophils are redundant for production of IgE and asthma. Our overarching hypothesis is that maternal exposure to DEP induces asthma susceptibility in offspring through IL1b and IL3 driven programming of the hematopoietic stem cell-basophil axis. In Aim 1, by performing stem cell transplantation experiments, we will establish links between DEP IL3R+ LT-HSCs, increased basopoiesis and predisposition to asthma. We will define molecular basis of DEP IL3R+ LT-HSC programming by analyzing their transcriptomes (RNA-seq) and chromatin remodeling at gene regulatory sites (ATAC-seq). In Aim 2 we will study importance of IL1b and IL3 in programming of the HSC-basophil axis for asthma induction. In our model, IL1b and IL3 are increased in offspring and maternal tissues, including maternal serum. We propose that maternal IL1b and IL3 are important at early stages of embryonic hematopoiesis, when HSCs undergo their initial divisions and embryonic sources of IL1b and IL3 are scarce. Offspring-derived IL1b and IL3 complete the HSC programming process, sustain basopoiesis at a high level, and contribute to basophil activation after maternal cytokines fade away. To define how maternal IL1b and IL3 are transferred to embryos, study their roles and roles of offspring- encoded IL1b and IL3, we will perform serum transfers, injections with radiolabeled cytokines, and combine IL1b or IL3 KO strategies with embryo transfers. In Aim 3 we will use human blood samples to study IL1b and IL3 guided basophil development in childhood asthma.