Evolution of autoreactive GC and epitope spreading in lupus

狼疮自身反应性GC和表位扩散的演变

• 批准号: 10736511
• 负责人: Michael Craig Carroll
• 金额: $ 48.29万
• 依托单位: BOSTON CHILDREN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-07-13 至 2028-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10736511
• 关键词: Adoptive Transfer; Affinity; Antigens; Autoantibodies; Autoantigens; Autoimmune Diseases; Autoimmunity; Automobile Driving; B-Lymphocytes; CD11 Antigens; CXCR3 gene; Cell surface; Cells; Chimera organism; Clone Cells; Complement 3d Receptors; Complement Receptor; Development; Disease; Effector Cell; Environment; Epitope spreading; Epitopes; Event; Evolution; Genetic; Health; ITGAX gene; Immunoglobulin-Secreting Cells; Kinetics; Longitudinal Studies; Lupus; Lymphoid; Malpighian corpuscles; Mediating; Modeling; Mus; Nuclear Antigens; Pathogenesis; Pathology; Patients; Peptides; Phenotype; Population; Regulation; Reporting; Role; Site; Specificity; Structure of germinal center of lymph node; Systemic Lupus Erythematosus; T-Lymphocyte; Testing; Time; autoreactive B cell; autoreactivity; humoral immunity deficiency; migration; mouse model; mutant; novel; pathogenic autoantibodies; response; transcriptomics

Systemic lupus erythematosus (SLE) is an incurable autoimmune disease and represents a substantial health problem in the population. Longitudinal studies of patients and murine models of SLE identify development of autoantibodies against new epitopes over time that correlate with increased pathology. The phenomena is referred to as epitope spreading, i.e. development of autoantibodies against determinants other than the initiating self-antigen. While the mechanism underlying epitope spreading remains unclear, we propose that spontaneous activation of a single B cell clone along with T cell help can promote activation and expansion of multiple distinct clones of nai"ve self-reactive B cells in both GC-dependent and -independent sites where they can be positively selected and undergo affinity maturation, compete and differentiate into effector cells leading to epitope spreading. In order to characterize the dynamics of self-reactive B cells arising in GC-dependent and -independent sites in more depth, we developed a novel adoptive transfer model. In this mouse model, donor B cells from WT or genetic mutants are transferred into lupus mice bearing a single BCR specific for nuclear antigen. We found that the self-reactive WT B cells underwent clonal selection and affinity maturation resulting in single WT clones dominating the GC response much like that observed in our previously reported mixed BM chimeras using the same lupus strain. Remarkably, the donor B cells rapidly expanded over 7 divisions in a GC-independent response that was Tlr 7 and MHC II dependent resulting in selection of a novel subset of effector B cells with a DN2-like phenotype observed in lupus patients (CD11c+CD21 lo). Unexpectedly, donor B cells deficient in CD11c failed to compete with WT donor cells and develop into effector B cells. In the current proposal, we will characterize further the events initiating spontaneous escape of B and T cell tolerance in GC-dependent and -independent responses resulting in epitope spreading. Moreover, we will characterize single TCR that provide functional help in co-stimulation of self-reactive B cells and their antigen specificity. Finally, we will track migration of activated donor cells in the splenic white pulp that give rise to self-reactive effector B cells using a novel spacial transcriptomics approach referred to as MERFISH. Two broad aims are proposed: Aim 1. Characterize the developmental kinetics and functional dynamics of self-reactive extra follicular ASCs. Aim 2. Characterize the role of Tfh cells in epitope spreading of GC-dependent and -independent self-reactive B cells.

系统性红斑狼疮 (SLE) 是一种无法治愈的自身免疫性疾病，是人群中的一个重大健康问题。对 SLE 患者和小鼠模型的纵向研究发现，随着时间的推移，针对新表位的自身抗体的发展与病理学的增加相关。这种现象被称为表位扩散，即针对起始自身抗原以外的决定因素产生自身抗体。虽然表位扩散的机制尚不清楚，但我们认为，单个 B 细胞克隆与 T 细胞的自发激活可以促进幼稚自身反应性 B 细胞在 GC 依赖性和非依赖性位点的多个不同克隆的激活和扩增，在这些位点中，它们可以被积极选择并经历亲和力成熟、竞争和分化为效应细胞，从而导致表位扩散。 为了更深入地表征 GC 依赖性和非依赖性位点中产生的自反应 B 细胞的动态，我们开发了一种新的过继转移模型。在该小鼠模型中，来自 WT 或基因突变体的供体 B 细胞被转移到具有核抗原特异性的单一 BCR 的狼疮小鼠中。我们发现，自身反应性 WT B 细胞经历了克隆选择和亲和力成熟，导致单个 WT 克隆主导 GC 反应，这与我们之前报道的使用相同狼疮菌株的混合 BM 嵌合体中观察到的情况非常相似。值得注意的是，供体 B 细胞在不依赖于 GC、依赖于 Tlr 7 和 MHC II 的反应中快速扩增超过 7 个分裂，从而选择出具有在狼疮患者中观察到的 DN2 样表型的新型效应 B 细胞子集 (CD11c+CD21 lo)。出乎意料的是，缺乏 CD11c 的供体 B 细胞未能与 WT 供体细胞竞争并发育成效应 B 细胞。在当前的提案中，我们将进一步描述在 GC 依赖性和非依赖性反应中启动 B 和 T 细胞耐受自发逃逸的事件，从而导致表位扩散。此外，我们将描述单个 TCR 的特征，该 TCR 为自身反应性 B 细胞及其抗原特异性的共刺激提供功能帮助。最后，我们将使用一种称为 MERFISH 的新型空间转录组学方法来追踪脾白髓中激活的供体细胞的迁移，这些细胞会产生自身反应性效应 B 细胞。提出了两个广泛的目标： 目标 1. 表征自反应性滤泡外 ASC 的发育动力学和功能动力学。 目标 2. 表征 Tfh 细胞在 GC 依赖性和非依赖性自身反应性 B 细胞表位扩散中的作用。