Identifying and Analyzing Genes Linked to Autoimmune Thyroid Diseases

描述（由申请人提供）：遗传因素在自身免疫性甲状腺疾病（AITD）、桥本甲状腺炎（HT）和格雷夫斯病（GD）的病因中发挥着重要作用。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性基因之间的相互作用。我们的目标是确定AITD易感基因，并剖析它们引起疾病的机制。我们在上一个资助期的研究结果是本项目具体目标的出发点，包括：（1）鉴定AITD亚群特异性的新AITD基因座（意大利患者和儿童AITD）;（2）缩小两个主要的复制AITD基因座（12 q和14 q），为基因鉴定奠定基础;（3）在CD 40基因中发现新的Kozak序列SNP，其通过增加CD 40的翻译效率而易患GD。在下一个资助期，我们将在这些发现的基础上继续努力，我们的具体目标是：（1）通过精细定位，在意大利GD患者和儿童AITD患者中，分别鉴定与3q和Xp & 10 q位点连锁的两个亚群特异性基因座中的AITD易感基因;亚群特异性AITD基因可能代表AITD患者亚群特异性的新治疗靶点;（2）应用连锁不平衡作图、单倍型分析和基因测序等方法，在12 q和14 q上的2个主要复制位点上确定AITD易感基因。(3)为了检验CD 40 Kozak SNP通过诱导抗原呈递细胞（APC）上CD 40的过度表达，引起增强的免疫应答，以及增加甲状腺细胞上CD 40的表达，从而将免疫应答集中于甲状腺，从而使GD易感的假设。体外研究：我们将检测CD 40 SNP基因型对甲状腺细胞和APC中CD 40表达、信号传导和功能的影响，以剖析SNP对这些细胞中CD 40表达和功能的影响。体内研究：我们正在产生甲状腺中过表达CD 40的转基因小鼠。这些小鼠将使我们能够在体内测试甲状腺中CD 40过表达对诱导实验性GD模型的易感性的影响。我们还将使用这些小鼠来测试CD 40阻断作为实验性GD的新疗法。总之，目前的提案直接建立在上一个赠款期获得的知识基础上。我们的方法已经成功地鉴定了新的疾病相关基因。建立甲状腺自身免疫的免疫遗传学通路将有助于更好地了解AITD的基本病因。这可能会对公共卫生产生重大影响，因为它可能有助于开发基于机制的自身免疫治疗方法，如CD 40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.