Defining how TCR strength of signal modulates Treg function

摘要/摘要 全球数百万人被诊断出患有多发性硬化症(MS)等自身免疫性疾病。 多发性硬化症的特点是由一种不适当的免疫反应所驱动的进行性脱髓鞘 中枢神经系统内的细胞。多发性硬化症和实验性自身免疫的主要危险因素 脑脊髓炎(EAE)动物模型，以及许多其他自身免疫性疾病(I型糖尿病， 类风湿性关节炎等)是特定的MHC II类分子。由于MHC II类递呈多肽抗原 无论是常规T细胞(Tconv)还是调节性T细胞(Tregs)，T细胞受体之间的相互作用 (TCR)和自体多肽：MHC(PMHC)在自身免疫性疾病的进展中起着关键作用。最重要的 Tregs的目的是以一种抗原特异性的方式抑制针对自身的免疫反应。Tregs认识到 如髓鞘等抗原通过其TCR，但TCR的基本措施和潜在的机制 与pMHC的相互作用尚不清楚。因此，对抗原特异性反应性的彻底理解 Tregs和这一活性是否可以被开发具有显著的治疗潜力。在这里，我们将剖析 用灵敏技术检测TCR与髓鞘抗原的相互作用 TCR结合，如亲和力和键寿命。值得注意的是，Tregs对TCR和TCR之间的粘合施加了力 PMHC，这最终反映在蛋白质相互作用时间的变化上。而Treg TCR据说 增强了信号的强度，从机械上讲，这个概念定义很差。我们发现 抑制性Tregs比Tconv细胞对pMHC键施加更大的力。此外，髓鞘特异的树突状细胞 未能压制施加较低水平的武力的人。因此，我们假设在抗原识别过程中， 力量大小的增加决定了Treg抑制表型。我们设计了三个目标来 测试这一假设：1)比较功能树和缺陷树的抗原结合参数；2) 根据力的大小确定Treg功能参数；以及3)工程TCR序列 使亲和力、结合寿命和对自身抗原的反应强度脱钩。因此，我们的项目将 对Treg在脱髓鞘过程中的功能和功能障碍的调控机制提供了新的见解 自身免疫性疾病。我们的工作将是第一次研究不同水平的力作为一种有效的生物标志物 Treg决定了它们的抑制效果、效力和表型稳定性。

Abstract/Summary Millions of people worldwide have been diagnosed with autoimmune diseases such as multiple sclerosis (MS). The hallmark of MS is progressive demyelination driven by an inappropriate immune response that attacks cells within the central nervous system. The dominant risk factor for MS, and experimental autoimmune encephalomyelitis (EAE) animal models, in addition to many other autoimmune diseases (type I diabetes, rheumatoid arthritis, etc) is specific MHC class II molecules. Since MHC class II presents peptide antigen to both CD4+ T conventional (Tconv) and regulatory T cells (Tregs), the interaction between the T cell receptor (TCR) and self peptide:MHC (pMHC) plays a pivotal role in autoimmune disease progression. The vital purpose of Tregs is to suppress immune responses against self in an antigen specific manner. Tregs recognize antigen such as myelin via their TCR, yet the fundamental measures and the underlying mechanism of TCR interaction with pMHC is unknown. Therefore, a thorough understanding of the antigen-specific reactivity of Tregs and whether this activity could be exploited has significant therapeutic potential. Here, we will dissect the interaction between TCR and myelin antigen using sensitive technologies to measure biophysical properties of TCR binding such as affinity and bond lifetimes. Of note, Tregs apply force to the bond between TCR and pMHC, which is ultimately reflected by changes in how long the proteins interact. While Treg TCRs are said to have enhanced strength of signal, mechanistically this concept is poorly defined. We discovered that suppressive Tregs apply more force to the pMHC bond than do Tconv cells. In addition, myelin-specific Tregs that fail to suppress apply lower levels of force. We therefore hypothesize that during antigen recognition, the increased magnitude of force determines the Treg suppressive phenotype. We have designed three aims to test this hypothesis that will: 1) compare antigenic binding parameters of functional versus defective Tregs; 2) determine Treg functional parameters dependent on the magnitude of force; and 3) engineer TCR sequences to decouple affinity, bond lifetime, and the level of force in response to self antigen. Thus, our project will provide novel insight into the mechanisms governing Treg function and dysfunction during demyelinating autoimmune disease. Our work will be the first to investigate various levels of force as a potent biomarker for Treg that dictates their suppressive efficacy, potency, and phenotypic stability.