Role of IL-18 in Crohn's Disease (CD)

IL-18 在克罗恩病 (CD) 中的作用

• 批准号: 7279461
• 负责人: Theresa Torres Pizarro
• 金额: $ 28.44万
• 依托单位: UNIVERSITY OF VIRGINIA
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-07-01 至 2010-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7279461
• 关键词: Accounting; Acute; Address; Affect; Alleles; Animal Model; Autoimmune Diseases; Automobile Driving; Binding; Biological Assay; Biological Models; Biopsy; Blood specimen; Bone Marrow; Bone Marrow Transplantation; CCL2 gene; Candidate Disease Gene; Cell Line; Cells; Characteristics; Chimera organism; Chronic; Chronic Phase; Chronic Phase of Disease; Classification; Colitis; Complex; Crohn' s disease; DNA Probes; Dendritic Cells; Development; Disease; Disease susceptibility; Dose; Electrophoretic Mobility Shift Assay; Environmental Risk Factor; Epithelial; Epithelial Cells; Etiology; Evaluation; Experimental Animal Model; Experimental Models; Family; Foundations; Funding; Gene Expression; Gene Expression Regulation; Genes; Genetic; Genetic Markers; Genetic Polymorphism; Genetic Predisposition to Disease; Genetic Variation; Genotype; Goals; Haplotypes; Hematopoietic; Human; Ileitis; Immune; Immune response; Immune system; In Vitro; Individual; Inflammation; Inflammatory; Inflammatory Bowel Diseases; Inflammatory disease of the intestine; Insulin-Dependent Diabetes Mellitus; Interleukin-11; Interleukin-18; Intestines; Knowledge; Laboratories; Linkage Disequilibrium; Measures; Mediating; Messenger RNA; Modality; Modeling; Molecular; Molecular Biology Techniques; Mouse Strains; Mucosal Immune Responses; Mucous Membrane; Multiple Sclerosis; Mus; Organ; Pathogenesis; Patients; Pattern; Phase; Plasma; Play; Population; Population Control; Predisposition; Production; Promoter Regions; Proteins; Quantitative Trait Loci; Range; Regulation; Regulator Genes; Reporter; Reporting; Research Personnel; Research Proposals; Rheumatoid Arthritis; Role; Sarcoidosis; Screening procedure; Severity of illness; Single Nucleotide Polymorphism; Site-Directed Mutagenesis; Sodium Dextran Sulfate; Source; Specificity; Staging; Subgroup; Susceptibility Gene; Testing; Thinking; Time; Tissues; Transcriptional Regulation; Transfection; Ulcerative Colitis; Variant; Virginia; Whole Blood; Wild Type Mouse; Work; base; cell type; chemokine; clinical phenotype; cytokine; design; disorder control; genetic association; genetic linkage; genetic variant; human study; in vivo; macrophage; mouse model; novel; programs; promoter; repaired; research study; response; transcription factor; transmission process

DESCRIPTION (provided by applicant): Although the precise etiology is unknown, inflammatory bowel disease (IBD) is thought to occur as a result of a dysregulated mucosal immune response to environmental factors in a genetically predisposed individual. IL-18 is a cytokine that plays an important role in the pathogenesis of several chronic Th1-mediated disorders, including Crohn's disease (CD). In fact, a dramatic shift in IL-18 expression occurs during CD from intestinal epithelial cells (IEC) to mucosal immune cells (i.e. macrophages and dendritic cells), as the severity of disease increases. In addition, recent evidence supports the role of IL-18 as a protective factor during the acute phase of mucosal immune responses, when IEC are the primary source of IL-18. This novel function for IL-18 contrasts with the pathogenic role IL-18 is believed to play in more chronic phases of Th1-mediated inflammation. A genetic basis for differences in IL-18 regulation and expression observed in IBD may exist since recent studies have reported the association of specific single nucleotide polymorphisms (SNPs) in the IL-18 promoter region and several autoimmune diseases. Therefore, using genetic and molecular biology techniques as well as experimental models intestinal inflammation, the present study is designed to investigate the specific genetic factors that regulate IL-18 synthesis and to determine the precise function of epithelial and immune cell-derived IL-18 in the acute versus chronic phases of IBD. The central hypothesis of the present proposal is that IL-18 plays a key role in regulating normal innate immune responses in the gut mucosa and dysregulation of IL-18 may result in chronic intestinal inflammation characteristic of IBD. The following three specific aims are proposed to test this hypothesis: 1) Determine the relationship between polymorphisms in the IL-18 promoter region and IBD. The role of IL-18 in IBD susceptibility will be defined using an association approach by screening for recently described IL-18 promoter polymorphisms and performing case association studies of these genetic markers in well-characterized IBD and control populations. IBD multiplex families will also be used to test linkage disequilibrium between these marker loci and putative disease susceptibility loci in order to further characterize the transmission pattern of allelic variants. 2) Define the mechanism(s) of polymorphic IL-18 gene regulation in different mucosal cell populations. The functional relevance of IL-18 promoter polymorphisms will be achieved by creation of reporter constructs, site-directed mutagenesis experiments, and in vitro transfection assays in epithelial and macrophage cell lines. In addition, differential transcription factor binding and subsequent transcriptional regulation will be assessed in order to determine how the IL-18 gene is differentially regulated by IL-18 promoter polymorphisms, and if transcriptional control varies among different intestinal cell types. 3) Evaluate the specific role of IL-18 derived from different gut mucosal cell populations in an in vivo setting using experimental models of intestinal inflammation. The extent and severity of disease will be assessed in mice genetically- and immunologically-manipulated to produce IL-18 in either hematopoietic- (i.e. immune cells) or non-hematopoietic-cells (i.e. epithelial cells) following the induction of acute or chronic intestinal inflammation. These experiments will mechanistically address, in an in vivo setting, if IL-18 derived from specific mucosal cell populations and expressed during the acute versus chronic phases of disease, are involved in the pathogenesis of IBD. The ultimate goal of the present research proposal is to define the precise role of IL-18 in CD in order to develop specific treatment modalities aimed at modifying the natural course of this devastating disease.

描述（由申请方提供）：尽管确切病因尚不清楚，但认为炎症性肠病（IBD）是遗传易感个体对环境因素的粘膜免疫应答失调的结果。IL-18是一种细胞因子，在包括克罗恩病（CD）在内的几种慢性Th 1介导的疾病的发病机制中起重要作用。事实上，随着疾病严重程度的增加，CD期间IL-18表达从肠上皮细胞（IEC）到粘膜免疫细胞（即巨噬细胞和树突状细胞）发生显著变化。此外，最近的证据支持IL-18在粘膜免疫应答的急性期作为保护因子的作用，此时IEC是IL-18的主要来源。IL-18的这种新功能与IL-18被认为在Th 1介导的炎症的更慢性阶段中发挥的致病作用形成对比。在IBD中观察到的IL-18调节和表达差异的遗传基础可能存在，因为最近的研究已经报道了IL-18启动子区域中的特定单核苷酸多态性（SNP）与几种自身免疫性疾病的关联。因此，使用遗传和分子生物学技术以及实验模型肠道炎症，本研究旨在研究调节IL-18合成的特定遗传因素，并确定上皮细胞和免疫细胞来源的IL-18在IBD急性期与慢性期的确切功能。本建议的中心假设是IL-18在调节肠粘膜中的正常先天免疫应答中起关键作用，并且IL-18的失调可能导致IBD的慢性肠道炎症特征。本研究拟从以下三个方面来验证这一假说：1）确定IL-18启动子区多态性与IBD的关系。IL-18在IBD易感性中的作用将使用关联方法通过筛选最近描述的IL-18启动子多态性并在充分表征的IBD和对照人群中进行这些遗传标记的病例关联研究来定义。IBD多重家族也将用于测试这些标记基因座和推定的疾病易感性基因座之间的连锁不平衡，以进一步表征等位基因变体的传播模式。2)定义不同粘膜细胞群体中多态性IL-18基因调控的机制。IL-18启动子多态性的功能相关性将通过创建报告构建体、定点诱变实验以及上皮细胞和巨噬细胞系中的体外转染测定来实现。此外，将评估差异转录因子结合和随后的转录调控，以确定IL-18基因如何受到IL-18启动子多态性的差异调控，以及不同肠细胞类型之间的转录调控是否不同。3)使用肠道炎症实验模型，在体内环境中评价源自不同肠道粘膜细胞群的IL-18的特定作用。在诱导急性或慢性肠道炎症后，在经遗传和免疫操作以在造血细胞（即免疫细胞）或非造血细胞（即上皮细胞）中产生IL-18的小鼠中评估疾病的程度和严重程度。这些实验将在体内环境中机械地解决源自特定粘膜细胞群并在疾病的急性期与慢性期期间表达的IL-18是否参与IBD的发病机制。本研究提案的最终目标是确定IL-18在CD中的确切作用，以开发旨在改变这种毁灭性疾病的自然病程的特定治疗方式。