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，是一个重大的健康问题的人口。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，即针对除起始自身抗原以外的决定簇的自身抗体的发展。尽管表位扩散的潜在机制仍不清楚，但我们提出，单个B细胞克隆的自发活化沿着T细胞的帮助可以促进多个不同的天然自身反应性B细胞克隆在GC依赖性和非GC依赖性位点的活化和扩增，在GC依赖性和非GC依赖性位点，它们可以被正向选择并经历亲和力成熟、竞争和分化成效应细胞，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身反应性B细胞的动力学，我们开发了一种新的过继转移模型。在该小鼠模型中，将来自WT或遗传突变体的供体B细胞转移到携带对核抗原特异性的单个BCR的狼疮小鼠中。我们发现自反应性WT B细胞经历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Tlr 7和MHC II依赖性的GC非依赖性应答中快速扩增超过7次分裂，导致选择具有在狼疮患者中观察到的DN 2样表型的效应B细胞的新亚群（CD 11 c + CD 21 lo）。出乎意料的是，CD11 c缺陷的供体B细胞不能与WT供体细胞竞争并发育成效应B细胞。在目前的建议，我们将进一步表征事件启动自发逃逸的B和T细胞耐受性的GC依赖性和非依赖性的反应，导致表位扩散。此外，我们将表征在自身反应性B细胞的共刺激中提供功能帮助的单个TCR及其抗原特异性。最后，我们将跟踪脾白色髓中活化供体细胞的迁移，这些细胞使用称为MERFISH的新型空间转录组学方法产生自反应效应B细胞。提出了两大目标： 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。 目标二。表征Tfh细胞在GC依赖性和非依赖性自身反应性B细胞的表位扩散中的作用。