The role of IL-4 and IL-4Ralpha in the multi-step process of Th2 development

描述（由申请人提供）：土壤传播的寄生线虫是世界范围内最常见的多细胞寄生虫感染之一。人类和小鼠的适应性宿主反应以CD4+ Th2细胞及其标志性细胞因子IL-4的存在为特征。Th2细胞和IL-4与针对寄生虫的保护性免疫反应有关，它们在某些免疫病理中是有害的，如抗原诱导的哮喘反应、特应性反应和过敏。虽然Th2细胞与线虫感染有关；然而，目前尚不清楚Th2细胞是如何从初始CD4+ T细胞发展而来的。大量研究表明，il - 4ra介导的信号和IL-4是体外初始CD4+ T细胞Th2发育所必需的，然而，对这些过程在体内的了解甚少。这主要是由于难以识别和跟踪由IL-4表达定义的Th2细胞。为了克服这些局限性，我们开发了双电子IL-4报告基因（4get）小鼠。与体外研究相反，我们的初步数据显示，在感染了小鼠蠕虫h.p olygyrus的IL4Ra-/- 4get小鼠中，Th2启动的效率惊人。因此，IL-4R和IL-4在Th2发育中的作用是有争议的。最近，我们培育了新的IL-4双报告小鼠（4get/KN2），并发现IL-4能力和IL-4的产生是不同的步骤。在这里，我们提出了一个新的模型，其中Th2的发展和IL-4的生产发生在几个不同的，可识别的步骤：激活,2。分化,3。扩张,4。4 . IL-4的产生；传播。在当前的应用中，我们将使用我们独特的双报告小鼠模型重新审视IL-4和il - 4ra介导的信号在Th2分化和IL-4产生中的作用。我们假设IL-4R功能不是CD4+ T细胞Th2启动成核所必需的，而是在该模型的多个其他步骤中发挥作用。在Aim 1中，我们将分析内源性T细胞群在Th2分化过程中的哪些步骤受到IL-4R信号的调节，以响应感染。在Aim 2中，我们将确定Th2分化的哪个步骤是由IL-4R信号直接介导的，抗原特异性CD4+ T细胞。我们将过继性地转移apTCR转基因CD4+ T细胞，并使用同源抗原作为Th2佐剂对多回红蝇幼虫进行免疫。在Aim 3中，我们将通过选择性谱系分析IL-4和IL-4Ra表达在Th2分化的多步骤过程中的作用。我们将产生各种骨髓嵌合体，这些嵌合体在选择性细胞谱系中缺乏各自的成分，并遵循内源性T辅助反应对感染的发展。总的来说，提出的目标将揭示IL-4R和IL-4调节体内Th2发育的多个步骤的机制。这些见解对于设计针对IL-4R和IL-4的激动和拮抗干预策略具有重要价值。

DESCRIPTION (provided by applicant): Soil transmitted parasitic nematodes are world wide one of the most commonly acquired infections with multi-cellular parasites. The adaptive host response in humans and mice is characterized by the presence of CD4+ Th2 cells and their signature cytokine IL-4. Th2 cells and IL-4 are associated with protective immune responses against helminth parasites they are detrimental in certain immunopathologies such as antigen-induced asthmatic reactions, atopy and allergy. While Th2 cells are associated with nematode infections; however, it is not clear how Th2 cells develop from naive CD4+ T cells in response to infection. Numerous studies have shown that IL-4Ra-mediated signals and IL-4 are required for the Th2 development of naive CD4+ T cells in vitro, however, very little is known about these processes in vivo. This is largely due to the difficulty to identify and track Th2 cells defined by IL-4 expression. To overcome these limitations we have developed bicistronic IL-4 reporter (4get) mice. In contrast to in vitro studies, our preliminary data show that Th2 priming occurs surprisingly efficient in IL4Ra-/- 4get mice infected with the murine helminth H. polygyrus. Thus, the role of IL-4R and IL-4 for Th2 development is controversial. Recently we have generated novel IL-4 dual-reporter mice (4get/KN2) and revealed that IL-4 competence and IL-4 production are distinct steps. Here we propose a novel model whereby Th2 development and IL-4 production occur in several distinct, identifiable steps: 1. activation, 2. differentiation, 3. expansion, 4. IL-4 production, 5. dissemination. In the current application we will revisit the role of IL-4 and IL-4Ra-mediated signals for Th2 differentiation and IL-4 production using our unique dual-reporter mouse model. We hypothesize that IL-4R functions are not required to nucleate the Th2 priming of CD4+ T cells but play a role in multiple other steps of this model. In Aim 1 we will analyze which step(s) in Th2 differentiation of the endogenous T cell population are regulated by IL-4R signals in response to infection. In Aim 2 we will determine which step(s) in Th2 differentiation are regulated by IL-4R signals mediated directly on naive, antigen-specific CD4+ T cells. We will adoptively transfer apTCR transgenic CD4+ T cells and immunize with the cognate antigen using H. polygyrus larvae as a Th2 adjuvant. In Aim 3 we will dissect the role of IL-4 and IL-4Ra expression by selective lineages in the multi-step process of Th2 differentiation. We will generate various bone marrow chimeras which lack the respective components in selective cellular lineages and follow the development of the endogenous T helper response to infection. Collectively the proposed Aims will reveal the mechanism by which IL-4R and IL-4 regulate the multiple steps of Th2 development in vivo. These insights are valuable for designing agonistic and antagonistic intervention strategies targeting the IL-4R and IL-4.