Immune Modulation of Intestinal Goblet Cell Responses

描述(申请人提供)：肠道线虫感染是全世界发病率和死亡率的主要原因，影响到多达四分之一的世界人口。我描述了一种独特的杯状细胞特异性蛋白，称为RELMB，它被分泌到肠腔的顶部，在脊椎动物抵抗肠道寄生虫感染方面发挥着新的作用。已证实Th2介导的肠道炎症反应，以宿主对线虫感染的反应为代表，导致杯状细胞增生。目前对宿主免疫系统调节杯状细胞特异性基因的发育以响应线虫感染的机制知之甚少。以RELMB为模型，我证明肠道中的杯状细胞发育受肠道特异性转录因子CDX2的调控。我进一步证明，在缺乏获得性免疫系统的情况下，RELMB的表达可以由细菌定植诱导，而最高水平的RELMa表达是由肠道线虫感染诱导的。我的总体假设是，[SIC]RELMB启动子的基础肠道特异性激活需要CDX转录因子家族，并且TLR及其下游信号通路与Th2介导的通路协同作用，以最佳地激活杯状细胞对寄生虫感染的反应。1)体外研究RELm-B启动子中NFkB和Stat6顺式作用元件的功能重要性，并研究其与CDX2的协同作用。2)将MyD88、NFkB1和Stat6基因定向缺失，建立小鼠旋毛虫线虫感染模型，以确定其对RELMa表达的影响。3)在感染T细胞的SCID小鼠中进行过继T细胞转移研究，以确定CD4+T细胞和Th2细胞因子在RELMB表达和线虫驱除中的作用。我的结果将有助于深入了解宿主先天免疫和获得性免疫之间的相互作用，并将阐明杯状细胞在结肠中作为免疫效应细胞发挥作用的机制。

DESCRIPTION (provided by applicant): Intestinal nematode infections are a major cause of morbidity and mortality throughout the world, affecting up to one quarter of the world's population. I describe a unique goblet cell-specific protein called RELMB which is secreted apically into the intestinal lumen, where it plays a novel role in vertebrate resistance to intestinal parasitic infection. It has been established that Th2-mediated intestinal inflammatory responses, typified by host responses to nematode infection, lead to goblet cell hyperplasia. Very little is currently known about the mechanisms by which the host immune system regulates the development of the goblet cell-specific genes in response to nematode infection. Using RELMB as a model, I show that goblet cell development in the intestinal tract is regulated by the intestine-specific transcription factor, Cdx2. I further demonstrate that RELMB expression can be induced by bacterial colonization in the absence of the acquired immune system, and that highest levels of RELMa expression are induced by intestinal nematode infection. My overall hypothesis is that basal intestine-specific activation of [sic] the RELMB promoter requires the Cdx family of transcription factors, and that TLRs and their downstream signaling pathways synergize with Th2-mediated pathways to optimally activate goblet cell responses to parasitic infections. 3 Specific Aims will be pursued: 1) The functional importance of NFkB and Stat6 cis-acting elements within the RELM-B promoter will be studied in vitro, and synergism with Cdx2 will be investigated. 2) A Trichuris muris model of murine nematode infection will be studied in mice with targeted deletions of MyD88, NFkB1, and Stat6 to determine the effect on RELMa expression. 3) Adoptive T cell transfer studies will be performed in T. muris infected SCID mice to determine the role of CD4+ T cells and Th2 cytokines in RELMB expression and nematode expulsion. My results will provide insight into the interactions between host innate and adaptive immunity, and will elucidate mechanisms by which goblet cells function as immune effector cells in the colon.