Identifying and Analyzing Genes Linked to Autoimmune Thyroid Diseases

描述(申请人提供)：遗传因素在自身免疫性甲状腺疾病(AITD)、桥本甲状腺炎(HT)和Graves病(GD)的病因中起主要作用。我们的假设是，AITD的病因取决于免疫调节基因和甲状腺特异基因之间的相互作用。我们的目标是确定AITD的易感基因，并剖析它们致病的机制。我们在上一次资助期间的发现，是这项建议具体目标的起点，包括：(1)识别针对AITD(意大利患者和儿童AITD)亚类的新的AITD基因座；(2)缩小两个主要的复制AITD基因座(12Q和14Q)，为基因鉴定奠定基础；(3)通过提高CD40的翻译效率，在CD40基因中发现易患GD的新的Kozak序列SNP。在下一个授权期，我们建议以这些发现为基础，我们的具体目标是：(1)通过精细定位意大利GD患者和儿童期AITD患者的AITD易感基因，确定AITD易感基因；AITD亚集特异基因可能代表AITD患者亚组的新的治疗靶点；(2)通过连锁不平衡作图、单倍型分析和基因测序，确定AITD易感基因在12Q和14Q的两个主要复制基因座。(3)验证CD40 Kozak SNP通过诱导抗原提呈细胞(APC‘s)上CD40的过度表达，增强免疫反应性，以及增加甲状腺细胞上CD40的表达，从而将免疫反应集中到甲状腺，从而诱发GD的假说。体外研究：我们将检测CD40基因SNP对甲状腺细胞和APC中CD40表达、信号和功能的影响，以剖析SNP对这些细胞中CD40表达和功能的影响。体内研究：我们正在培育在甲状腺中过度表达CD40的转基因小鼠。这些小鼠将使我们能够在体内测试CD40在甲状腺中过度表达对诱导实验性GD模型的易感性的影响。我们还将利用这些小鼠来测试CD40阻断作为实验性GD的一种新疗法。总而言之，目前的提议直接建立在前一个赠款期间所获得的知识的基础上。我们的方法已经成功地识别了新的疾病相关基因。建立引起甲状腺自身免疫的免疫遗传途径将有助于更好地了解AITD的基本病因。这可能会对公众健康产生重大影响，因为它可能会促进基于机制的自身免疫治疗的发展，如CD40阻断。

DESCRIPTION (provided by applicant): Genetic factors play a major role in the etiology of autoimmune thyroid diseases (AITD), Hashimoto's thyroiditis (HT) & Graves' disease (GD). Our hypothesis is that the etiology of AITD depends on interactions between immune regulatory genes and thyroid specific genes. Our goals are to identify the AITD susceptibility genes and to dissect the mechanisms by which they cause disease. Our findings during the last grant period, which are the starting point for the specific aims of this proposal, included: (1) Identifying novel AITD loci which are specific for subsets of AITD (Italian patients, & childhood AITD); (2) Narrowing down two major replicated AITD loci (12q & 14q), setting the stage for gene-identification; (3) Discovering a new Kozak sequence SNP in the CD40 gene that predisposes to GD by increasing the translational efficiency of CD40. For the next grant period we propose to build on these finding, and our specific aims are: (1) To identify the AITD susceptibility genes in the two subset specific loci by fine mapping in Italian GD patients, linked to a locus on 3q, and childhood AITD, linked to loci on Xp & 10q; the subset-specific AITD genes may represent novel therapeutic targets specific to subgroups of AITD patients; (2) To identify the AITD susceptibility genes in the 2 major replicated loci on 12q & 14q by linkage disequilibrium mapping, haplotype analysis, and gene sequencing. (3) To test the hypothesis that the CD40 Kozak SNP predisposes to GD by inducing over-expression of CD40 on antigen presenting cells (APC's), causing augmented immune responsiveness, as well as increasing CD40 expression on thyrocytes, thereby focusing the immune response to the thyroid. In vitro studies: we will examine the effects of the CD40 SNP genotypes on CD40 expression, signaling, and function in thyrocytes and APC's, in order to dissect the effects of the SNP on CD40 expression & function in these cells. In vivo studies: We are generating transgenic mice over-expressing CD40 in the thyroid. These mice will enable us to test, in vivo, the effects of CD40 over-expression in the thyroid on susceptibility to the induction of an experimental GD model. We will also use these mice to test CD40 blockade as a novel therapy for experimental GD. In summary, the current proposal builds directly on the knowledge gained in the previous grant period. Our approach has already been successful in identifying novel disease-associated genes. Establishing the immunogenetic pathways causing thyroid autoimmunity will lead to a better understanding of the basic etiology of AITD. This could have a major impact on public health, as it may facilitate the development of mechanism-based treatments in autoimmunity, such as CD40 blockade.