Role of the transcription factor Ikaros in development of autoimmune disease

摘要 自身免疫性疾病是一种慢性且经常致残的疾病，影响数百万美国人。电流 治疗有助于预防自身免疫性疾病的症状，但没有治愈方法。自身免疫性疾病 被认为是由于遗传倾向和环境因素的结合，但病因是 没有完全理解。为了开发新的和改进的治疗方法，并有可能找到治愈方法， 对自身免疫性疾病的潜在分子机制的理解是必不可少的。采用了新 在建立的突变小鼠品系中，我们发现编码 转录因子Ikaros，导致免疫耐受的严重缺陷，具有高水平的自身反应性免疫缺陷。 在非常年轻的小鼠的血清中的抗体。抗体是由B细胞产生的， 自身反应性抗体表明，Ikaros是控制B细胞如何对抗原作出反应以及 确保对自己的宽容。Ikaros在人类自身免疫性疾病中的作用得到了最近全基因组研究的支持。 关联研究（GWAS），其中Ikaros基因座（IKZF 1）的遗传变异与 几种自身免疫性疾病此外，最近的研究报告， 携带IKZF1突变。我们建议使用Ikaros突变小鼠作为一种新的自身免疫模型， 研究Ikaros突变B细胞耐受性破坏的分子机制。我们有 初步数据表明，Ikaros调节B细胞成熟的两个不同阶段，这两个阶段对 适当的耐受性：中央耐受检查点和对Ag上共刺激信号的要求 在外围相遇。我们将使用这个小鼠模型来直接测试Ikaros限制的假设 自身反应性B细胞通过加强中枢耐受性和建立对“第二信号”的需求 （表示危险）通过表观遗传机制。因此，我们的研究设计集中在一个 使用体内和离体组合，了解中枢耐受性和B细胞自身反应性 接近。直接评估基因表达，表观遗传和信号通路与适当的 与异常的B细胞活化相比。具体来说，我们将研究Ikaros在BCR信号传导中的作用， 建立中枢耐受性（目标1）。我们将使用我们的Ikaros突变模型来研究 Ikaros在调节成熟B细胞对抗原反应的分子机制中的作用（目的2）。最后，我们将 检查B细胞的内在，以及不同免疫细胞的相对外在贡献和作用 在观察到的B细胞耐受性的破坏中的谱系（Aim 3）。

ABSTRACT Autoimmune diseases are chronic and often disabling illnesses that affect millions of Americans. Current treatments help to prevent the symptoms of autoimmune disease, but there are no cures. Autoimmune disease is thought to be due to a combination of genetic predispositions and environmental factors, but the etiology is not fully understood. In order to develop new and improved treatments, and to potentially find a cure, a better understanding of the underlying molecular mechanisms of autoimmune disease is essential. Using a newly established strain of mutant mice, we found that a small targeted deletion in the gene encoding the transcription factor Ikaros, resulted in a profound defect in immune tolerance, with high levels of autoreactive antibodies in the serum of very young mice. Antibodies are produced by B cells, and the presence of autoreactive antibodies indicates that Ikaros is necessary to control how B cells respond to antigen and to ensure tolerance to self. A role for Ikaros in human autoimmune disease is supported by recent genome-wide association studies (GWAS), where genetic variants in the Ikaros gene locus (IKZF1) have been linked to several autoimmune diseases. Furthermore, recent studies have reported patients with autoimmune disease that carry IKZF1 mutations. We propose to employ our Ikaros-mutant mice as a new model of autoimmunity to investigate the molecular mechanisms underlying the break of tolerance in Ikaros-mutated B cells. We have preliminary data suggesting that Ikaros regulates two distinct stages of B-cell maturation that are critical for proper tolerance: The central tolerance checkpoint and the requirement for costimulatory signal upon Ag encounter in the periphery. We will use this mouse model to directly test the hypothesis that Ikaros limits autoreactive B cells by enforcing central tolerance and establishing a requirement for the “second signal” (indicating danger) through epigenetic mechanisms. Accordingly, our study design is focused on an understanding of central tolerance and B-cell autoreactivity, using a combination of in vivo and ex vivo approaches. to directly assess the gene expression, epigenetic and signaling pathways associated with proper versus aberrant B cell activation. Specifically, we will investigate the role of Ikaros in BCR signaling and establishment of central tolerance (Aim 1). We will employ our Ikaros-mutant model to investigate the role of Ikaros in the molecular mechanisms regulating mature B-cell response to antigen (Aim 2). Lastly, we will examine the B-cell intrinsic, as well as the relative extrinsic contributions and roles of different immune cell lineages in the observed break of B-cell tolerance (Aim 3).