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)是一种不可治愈的自身免疫性疾病，在人群中是一个严重的健康问题。对SLE患者和小鼠模型的纵向研究发现，随着时间的推移，与病理增加相关的针对新表位的自身抗体的发展。这种现象被称为表位扩散，即产生针对除起始自身抗原以外的决定因素的自身抗体。虽然表位扩散的机制尚不清楚，但我们认为，单个B细胞克隆的自发激活和T细胞有助于促进多个不同克隆的NAIve自身反应性B细胞在GC依赖和非独立位点的激活和扩张，在那里它们可以被正向选择，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。 为了更深入地描述发生在GC依赖和非GC依赖部位的自反应性B细胞的动力学，我们发展了一个新的采用转移模型。在这个小鼠模型中，来自WT或基因突变的供体B细胞被转移到携带单一核抗原特异性BCR的狼疮小鼠体内。我们发现，具有自身反应性的WT B细胞经过克隆选择和亲和成熟，导致单个WT克隆主导GC反应，与我们之前报道的使用相同狼疮株的混合BM嵌合体中观察到的情况非常相似。值得注意的是，供体B细胞在一种依赖于TLR7和MHC II的GC非依赖性反应中，在7个分裂中迅速扩张，导致选择了一种新的效应B细胞亚群，在狼疮患者中观察到了类似DN2的表型(CD11c+CD2110)。出乎意料的是，CD11c缺陷的供体B细胞未能与WT供体细胞竞争并发育成效应性B细胞。在目前的方案中，我们将进一步描述在GC依赖和非依赖反应中启动B和T细胞耐受性自发逃逸的事件，从而导致表位扩散。此外，我们将描述在共刺激自身反应性B细胞及其抗原特异性方面提供功能帮助的单个TCR的特征。最后，我们将使用一种被称为MerFish的新的空间转录切割学方法来跟踪激活的供体细胞在脾白髓中的迁移，这些细胞产生自我反应的效应B细胞。我们提出了两个主要目标： 目的1.研究自身反应性毛囊外ASCs的发育动力学和功能动力学。 目的2.研究TFH细胞在GC依赖和非GC依赖的自身反应性B细胞表位扩展中的作用。