Maternal programming of the stem cell-basophil axis for asthma

项目总结/摘要 越来越多的流行病学研究将儿童哮喘与母亲环境暴露联系起来 其中提供了柴油尾气和香烟烟雾的最有力证据。母体暴露如何导致 后代的哮喘是未知的。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 通过让他们的母亲接触柴油机尾气颗粒（DEP）我们的数据表明，在这个DEP驱动的模型中， 哮喘易感信息部分通过后代长期造血干细胞亚群传递 细胞（LT-HSC），以干细胞记忆的形式。该亚群通过IL 3的表达来区分自身。 受体，并被编程为通过DEP诱导的细胞因子的协同作用增强嗜碱性粒细胞的产生。 IL 1b和IL 3。IL 1b和IL 3之间协同作用的一个关键机制是IL 1b增加 干细胞对IL 3的敏感性部分是由于IL 1 b介导的IL 3 R B链上调。除了 扩大嗜碱性细胞谱系，IL 3和IL 1b可能增强其促进哮喘的能力。先前 研究表明IL 1b增强嗜碱性粒细胞组胺释放并且IL 3有效地刺激它们的IL 4产生， 播下了第二型免疫反应的种子与此一致，在DEP后代中，嗜碱性粒细胞过度表达 IL 4。IL 3/IL 1b引发的、扩增的、IL 4过表达的嗜碱性粒细胞群体成为这种类型的关键驱动因素。 2过敏原攻击后的免疫应答和哮喘。DEP幼仔中嗜碱性粒细胞的耗竭阻止了 过敏原特异性IgE和哮喘的发展。这与在普通过敏原中获得的数据相反- 基于嗜碱性粒细胞对于IgE和哮喘的产生是多余的模型。我们的首要假设是 母亲暴露于DEP通过IL 1b和IL 3驱动诱导后代哮喘易感性， 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 IL 3R + LT-HSC，增加的基底细胞生成和易患 哮喘我们将通过分析它们的转录组来确定DEP IL 3R + LT-HSC编程的分子基础 （RNA-seq）和基因调控位点处的染色质重塑（ATAC-seq）。在目标2中，我们将研究重要性 IL 1b和IL 3在HSC-嗜碱性粒细胞轴编程中的作用。在我们的模型中，IL 1b和IL 3是 在后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是重要的，此时HSC经历它们的初始分裂， IL 1b和IL 3的胚胎来源是稀缺的。后代衍生的IL 1b和IL 3完成HSC编程 过程，维持高水平的碱性细胞生成，并在母体细胞因子消退后促进嗜碱性粒细胞活化 距离为了确定母体IL 1b和IL 3是如何转移到胚胎中的，研究它们的作用和后代的作用- 编码IL 1b和IL 3，我们将进行血清转移，注射放射性标记的细胞因子，并联合收割机 IL 1b或IL 3 KO策略与胚胎移植。在目标3中，我们将使用人类血液样品来研究IL 1b和IL 13。 IL-3在儿童哮喘中指导嗜碱性粒细胞发育

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.