REGULATION OF IL 12 IN MUCOSAL IMMUNITY AND IBD

拟议研究的目的是了解 人炎症性肠病（IBD）的免疫发病机制 表征白细胞介素-12（IL-12）的调节表达。 IL-12 是具有多效性效应的异源二聚体细胞因子，包括 辅助性T细胞1（Th 1）应答的诱导和维持。 体内，Th 1 免疫反应对于免疫力的发展至关重要， 细胞内微生物在自身免疫性疾病中，Th 1细胞可以介导 组织损伤辅助性T细胞2（Th 2）在感染中是有害的。 细胞内生物，但可能抑制由Th 1引起的组织损伤 自身免疫性和炎症性疾病的反应。最近描述 动物模型强调了Th 1和Th 2亚群在免疫系统中的重要性。 慢性肠粘膜炎症的发病机制。的分泌 抗原呈递细胞（APC）的IL-12是免疫应答的专性信号。 产生稳定的Th 1表型。因此，IL-12的调节 基因表达可能是影响Th亚群的主要事件 Th体内分化和细胞因子产生。两种IL-2的表达 12个基因将在APC系中通过定义以下效应来表征： 潜在的诱导剂，并确定mRNA诱导的动力学。的5 将从鼠基因组DNA中分析每个基因的调控区 通过转录起始位点作图、限制性酶切作图和DNA测序克隆 测序 然后将确定IL-12表达是否是 通过调节转录起始，mRNA稳定性， 或转录减弱。最后，每个IL-1的启动子区域 12基因的功能将通过描述顺式作用 参与IL-12转录起始的控制元件 瞬时和稳定转染测定。 反式作用因子 通过电泳迁移率分析IL-12基因表达 转移测定和DNA酶I足迹法。 一旦这些调控因素 鉴定，它们对IL-12表达的贡献将在 特定疾病模型。通过表征IL-1的调节表达， 12在APC中，决定Th 1应答的分子机制可能是 介绍了这些机制可以用来改变宿主的免疫力 感染性和炎症性疾病，包括IBD。

The objective of the proposed study is to understand the immunopathogenesis of the human inflammatory bowel diseases (IBD) by characterizing the regulated expression of interleukin-12 (IL-12). IL-12 is a heterodimeric cytokine with pleiotropic effects, including the induction and maintenance of T helper 1 (Th1) responses. In vivo, Th1 responses are critical in the development of immunity against intracellular microbes. In autoimmune disorders, Th1 cells may mediate tissue injury. T helper 2 (Th2) cells are deleterious in infections with intracellular organisms, but may inhibit the tissue damage elicited by Th1 responses in autoimmune and inflammatory diseases. Recently described animal models highlight the importance of Th1 and Th2 subsets in the pathogenesis of chronic intestinal mucosal inflammation. The secretion of IL-12 by antigen presenting cells (APCs) is an obligate signal for the generation of a stable Th1 phenotype. Therefore, the regulation of IL-12 gene expression is likely to be a primary event influencing Th subset differentiation and cytokine production Th vivo. Expression of the two IL- 12 genes will be characterized in APC lines by defining the effects of potential inducers, and determining the kinetics of mRNA induction. The 5 regulatory region of each gene will be analyzed from murine genomic DNA clones by transcription start site mapping, restriction mapping, and DNA sequencing. It will then be determined whether IL-12 expression is regulated through modulation of transcription initiation, mRNA stability, or attenuation of transcription. Finally, the promotor region for each lL- 12 gene will be functionally characterized by describing cis-acting control elements involved in initiation of IL-12 transcription in transient and stable transfection assays. Trans-acting factors involved in IL-12 gene-expression will be analyzed by electrophoretic mobility shift assays and DNAse I footprinting. Once these regulatory elements are identified, their contribution to IL-12 expression will be studied in specific disease models. By characterizing the regulated expression of IL- 12 in APC, molecular mechanisms that determine Th1 responses may be described. These mechanisms may then be exploited to alter host immunity in infectious and inflammatory disorders, including IBD.