Molecular determinants of immune tolerance in Graves' disease

自身免疫性甲状腺疾病是最普遍的自身免疫性疾病，Graves病（GD）一生中影响近2%的女性，全球影响750万人。在GD中，免疫系统产生抗体，刺激甲状腺，导致甲状腺激素分泌过多（甲状腺功能亢进）。甲状腺激素过多会影响身体的多个系统，包括心脏、循环、神经系统、皮肤和代谢调节，引起心率升高、易怒、出汗和体重减轻等多种症状。甲状腺眼病是GD的一种并发症，也会导致面部畸形，包括眼睛突出、复视和偶尔失明。自1951年引入抗甲状腺药物卡咪唑以来，目前GD的治疗方法基本保持不变。在服用卡咪唑片6个月或更长时间后，大约50%的人病情会得到持久缓解，而另外50%的人会复发，这是年轻人的规律。复发患者最终可能需要放射性碘治疗或手术干预来切除甲状腺，这两种方法都会导致终生依赖甲状腺激素替代疗法，并伴有监测费用。格雷夫斯病在家族中有很强的遗传性，80%的风险是由遗传因素造成的。此外，甲状腺过度活跃的确切原因是已知的：模仿促甲状腺激素（TSH）形状的抗体持续刺激TSH受体。鉴于这些抗tsh受体抗体（TRAbs）在引起GD中的核心作用，我们需要更多地了解为什么这些抗体是由免疫系统的抗体产生臂（也称为体液免疫系统）产生的。骨髓源性B淋巴细胞及其衍生细胞类型、浆母细胞和浆细胞负责制造这些TRAb抗体。我的研究目的是了解抗甲状腺药物治疗后TRAbs消失而持续缓解的GD患者的体液免疫系统与TRAbs持续存在并在相同药物治疗后立即复发的患者的体液免疫系统有何不同。这项研究将涉及120名成年GD患者，他们即将停止服用常规的抗甲状腺药物治疗。我将比较一半将继续治愈他们的甲状腺疾病（缓解组）和那些甲状腺过度活动即将回来（复发组）之间的许多因素。首先，将测量几种B淋巴细胞生成速率和发育的血液标志物，包括TRAbs，循环B细胞生长因子(如；BAFF)和被称为KRECs的小DNA环，它指示B淋巴细胞的产生速度。然后利用rna测序技术检测各组纯化B细胞中不同基因产物的数量。这将使我能够识别B细胞分子指纹，以区分进入疾病缓解期的人与即将复发的人。最后，我们将研究这些基因表达差异背后的遗传变异，并以此来确认复发或缓解现象的遗传（基因组）基础。这将提供持续缓解者和复发者之间B细胞分子差异（包括RNA和基因组）的目录，以及关于他们的体液免疫反应的功能信息。这将为免疫系统如何能够在自身免疫性疾病后再次变得耐受提供新的见解，这将有助于推动新疗法的发展。了解决定对治疗反应的因素也将提供预后信息，并允许针对个体进行治疗。许多其他自身免疫性疾病有复发和缓解过程，因此这项工作可能具有广泛的相关性。

Autoimmune thyroid diseases are the most prevalent of the autoimmune conditions, with Graves' disease (GD) affecting close to 2% of women over a lifetime and impacting 7.5 million worldwide. In GD, the immune system generates antibodies that stimulate the thyroid gland leading to excessive thyroid hormone production (hyperthyroidism). Excess thyroid hormone affects multiple systems within the body including the heart, circulation, nervous system, skin and metabolic regulation, causing diverse symptoms such as elevated heart rate, irritability, sweating and weight loss. Thyroid eye disease, a complication of GD, also causes facial disfigurement with protuberance of the eyes, double vision and occasionally loss of vision. The current treatment for GD has remained largely unchanged since 1951, when the antithyroid drug carbimazole was introduced. Following a 6 month or longer course of carbimazole tablets about 50% of people will have a durable remission of their condition, whereas the other 50% will relapse, which is the rule in younger people. Relapsing patients may ultimately require radio-iodine treatment or surgical intervention to remove the thyroid gland, both leading to lifelong dependence on thyroid hormone replacement, with attendant monitoring costs.Graves' disease runs strongly in families and 80% of the risk has been shown to be owing to genetic factors. In addition, the exact cause of the thyroid overactivity is known: antibodies that mimic the shape of thyroid stimulating hormone (TSH) which persistently stimulate the TSH-receptor. Given the central role of these anti-TSH receptor antibodies (TRAbs) in causing GD, we need to understand more about why these antibodies are produced by the antibody-producing arm of the immune system (also known as the humoral immune system). Bone marrow-derived B lymphocytes, and their derivative cell types, plasmablasts and plasma cells are responsible for making these TRAb antibodies. My fellowship aims to understand what is different about the humoral immune system in GD patients who sustain a prolonged remission with disappearance of TRAbs following antithyroid drugs, compared to those whose TRAbs persist and who immediately relapse following the same medication.The study will involve a group of 120 adult GD patients who are about to stop taking the usual antithyroid drug therapy. I will compare many factors between the half who will remain cured of their thyroid disease (remission group) and those whose thyroid overactivity is about to come back (relapse group). Firstly, several blood markers of B lymphocyte production rate and development will be measured, including TRAbs, circulating B cell growth factors (eg. BAFF) and small DNA loops known as KRECs which indicate the rate of B lymphocyte production. Then the quantity of different gene-products in purified B cells from each group will also be examined using the powerful technique of RNA-sequencing. This will allow me to identify a B cell molecular fingerprint that distinguishes people entering disease remission vs those headed for relapse. Lastly, we will look at the genetic variations underlying these differences in gene expression and use this to confirm an inherited (genomic) underpinning for the relapse or remission phenomena. This will provide a catalogue of molecular differences (both RNA and genomic) in B cells between people with sustained remission and those who relapsed, along with functional information about their humoral immune response. This will give novel insights into how the immune system is able to become tolerant again following an autoimmune disease, which will help to advance the development of new treatments. Understanding the factors that determine the response to therapy will also give prognostic information and allow treatment to be tailored to the individual. Many other autoimmune diseases have a relapsing and remitting course, so this work may have widespread relevance.