Department of Rheumatology & Clinical Immunology, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands; Center for Translational Immunology, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands.
Department of Viroscience, Erasmus Medical Center Rotterdam, Rotterdam, the Netherlands.
J Autoimmun. 2021 Feb;117:102574. doi: 10.1016/j.jaut.2020.102574. Epub 2020 Dec 8.
The T-cell receptor (TCR) is a highly polymorphic surface receptor that allows T-cells to recognize antigenic peptides presented on the major histocompatibility complex (MHC). Changes in the TCR repertoire have been observed in several autoimmune conditions, and these changes are suggested to predispose autoimmunity. Multiple lines of evidence have implied an important role for T-cells in the pathogenesis of Systemic Sclerosis (SSc), a complex autoimmune disease. One of the major questions regarding the roles of T-cells is whether expansion and activation of T-cells observed in the diseases pathogenesis is antigen driven. To investigate the temporal TCR repertoire dynamics in SSc, we performed high-throughput sequencing of CD4 and CD8 TCRβ chains on longitudinal samples obtained from four SSc patients collected over a minimum of two years. Repertoire overlap analysis revealed that samples taken from the same individual over time shared a high number of TCRβ sequences, indicating a clear temporal persistence of the TCRβ repertoire in CD4 as well as CD8 T-cells. Moreover, the TCRβs that were found with a high frequency at one time point were also found with a high frequency at the other time points (even after almost four years), showing that frequencies of dominant TCRβs are largely consistent over time. We also show that TCRβ generation probability and observed TCR frequency are not related in SSc samples, showing that clonal expansion and persistence of TCRβs is caused by antigenic selection rather than convergent recombination. Moreover, we demonstrate that TCRβ diversity is lower in CD4 and CD8 T-cells from SSc patients compared with memory T-cells from healthy individuals, as SSc TCRβ repertoires are largely dominated by clonally expanded persistent TCRβ sequences. Lastly, using "Grouping of Lymphocyte Interactions by Paratope Hotspots" (GLIPH2), we identify clusters of TCRβ sequences with homologous sequences that potentially recognize the same antigens and contain TCRβs that are persist in SSc patients. In conclusion, our results show that CD4 and CD8 T-cells are highly persistent in SSc patients over time, and this persistence is likely a result from antigenic selection. Moreover, persistent TCRs form high similarity clusters with other (non-)persistent sequences that potentially recognize the same epitopes. These data provide evidence for an antigen driven expansion of CD4/CD8 T-cells in SSc.
T 细胞受体（TCR）是一种高度多态的表面受体，使 T 细胞能够识别主要组织相容性复合体（MHC）上呈现的抗原肽。在几种自身免疫性疾病中观察到 TCR 库的变化，这些变化被认为易患自身免疫。多条证据表明 T 细胞在系统性硬化症（SSc）的发病机制中起重要作用，SSc 是一种复杂的自身免疫性疾病。关于 T 细胞作用的主要问题之一是，在疾病发病机制中观察到的 T 细胞的扩增和激活是否是抗原驱动的。为了研究 SSc 中 TCR 库的时间动态，我们对来自 4 名 SSc 患者的纵向样本进行了 CD4 和 CD8 TCRβ 链的高通量测序，这些样本在至少两年的时间内收集。库重叠分析显示，随着时间的推移，来自同一个体的样本共享大量 TCRβ 序列，表明 CD4 和 CD8 T 细胞中 TCRβ 库具有明显的时间持续性。此外，在一个时间点发现的高频 TCRβ 也在其他时间点发现高频（即使在将近四年之后），这表明优势 TCRβ 的频率在很大程度上是随时间保持一致的。我们还表明，在 SSc 样本中，TCRβ 生成概率与观察到的 TCR 频率没有相关性，这表明 TCRβ 的克隆扩增和持续存在是由抗原选择而不是趋同重组引起的。此外，我们证明与健康个体的记忆 T 细胞相比，SSc 患者的 CD4 和 CD8 T 细胞中的 TCRβ 多样性较低，因为 SSc TCRβ 库主要由克隆扩增的持续 TCRβ 序列主导。最后，我们使用“通过抗原结合部位热点对淋巴细胞相互作用进行分组”（GLIPH2），鉴定了具有潜在识别相同抗原的同源序列的 TCRβ 序列簇，并包含在 SSc 患者中持续存在的 TCRβ。总之，我们的结果表明，CD4 和 CD8 T 细胞在 SSc 患者中随时间推移具有高度持续性，这种持续性可能是抗原选择的结果。此外，持续的 TCR 与其他（非）持续序列形成具有高度相似性的簇，这些序列可能识别相同的表位。这些数据为 SSc 中 CD4/CD8 T 细胞的抗原驱动性扩增提供了证据。
