"Perturbation of peripheral B cell tolerance by the lupus susceptibility loci"

描述（由申请人提供）：自身免疫性疾病与免疫耐受性丧失有关，生物体的适应性免疫细胞无法区分“自我”和“非自我”。虽然B细胞中枢耐受（在骨髓中）的存在现在已经很好地建立，但我们对外周耐受（在外周淋巴器官中）的细胞和分子机制及其在自身免疫性疾病如“狼疮”中的扰动的认识是有限的。理解外周B细胞耐受性是重要的，因为这些耐受性机制的干扰调节可能允许自身反应性B细胞和致病性IgG自身抗体的发展，其有助于自身免疫性疾病，如系统性红斑狼疮（SLE）。在这里，我们使用了B细胞抗原受体（BCR）敲入小鼠模型（HKIR），其产生双重反应性{胂酸盐（Ars）和DNA-染色质-自身抗原反应性} B细胞。我们以前的研究表明，双反应HKIR B细胞可以发展成滤泡B细胞和分化成抗体形成细胞（AFC）免疫后，与Ars结合的外来抗原。这些双反应性细胞也可以进入生发中心（GC），但由于它们的自身反应性受到GC耐受机制的负调节或阻止其在GC中扩增，并且不能有效地成为记忆B细胞。因此，与将B细胞排除在外周淋巴滤泡（包括AFC和GC途径）之外的其他自身反应性转基因小鼠模型相比，HKIR模型非常适合研究调节自身抗体产生的核抗原特异性HKIR B细胞的AFC和GC介导的B细胞耐受途径。我们发表的和初步的数据表明，外周B细胞耐受性AFC和GC途径中的工作可以改变狼疮易感基因座Sle 1的存在。然而，Sle 1对AFC和GC记忆耐受性的影响似乎是不完全渗透的，表明T和/或髓样区室的缺陷可能需要外周B细胞耐受性的丧失，导致IgG ANA的产生和狼疮的发展。在这里，我们建议确定的Sle 1基因座内的易感基因，驱动B细胞发展到AFC和GC途径，导致外周B细胞耐受性的损失（Aim-1）。在Aim-2中，我们将确定受Sle 3间隔内的易感基因影响的细胞类型（T和/或DC），所述Sle 3间隔提供B细胞帮助，从而促进GC耐受性的破坏。在目的-3中，我们将研究I型干扰素（IFN-1）如何加速GC记忆耐受性破坏的过程，并允许狼疮易感小鼠产生强大的自身抗体。 公共卫生相关性：完成拟议的研究将提供重要的新的见解，外周自身耐受性的作用，在AFC和GC记忆通路沉默自身抗体的生产。这些研究也将有助于我们理解，由于狼疮易感基因座的存在，这些通路的扰动如何导致自身抗体产生和自身免疫性疾病狼疮的发展。

DESCRIPTION (provided by applicant): Autoimmune diseases are associated with a loss of immunological tolerance, a failure of an organism's adaptive immune cells to distinguish between 'self' and 'non-self'. While the existence of B cell central tolerance (in the bone marrow) is now well-established, our knowledge about the cellular and molecular mechanisms of peripheral tolerance (in peripheral lymphoid organs) and their perturbation in autoimmune diseases such as 'lupus' is limited. Understanding peripheral B cell tolerance is important as perturbed regulation of these tolerance mechanisms may allow for the development of autoreactive B cells and pathogenic IgG autoantibodies that contribute to autoimmune diseases such as systemic lupus erythematosus (SLE). Here, we have used a B cell antigen receptor (BCR) knock-in mouse model (HKIR) that yields dual-reactive {Arsonate (Ars) and DNA-chromatin-self-antigen- reactive} B cells. We previously showed that dual-reactive HKIR B cells can develop into follicular B cells and differentiate into antibody forming cells (AFCs) upon immunization with Ars-conjugated foreign antigen. These dual-reactive cells also can enter germinal centers (GCs), but due to their autoreactivity are negatively regulated or prevented from expanding in GCs by a GC tolerance mechanism and do not efficiently become memory B cells. Therefore, in contrast to other autoreactive transgenic mouse models in which B cells are excluded from the peripheral lymphoid follicles including AFC and GC pathways, the HKIR model is well suited to study AFC and GC-mediated B cell tolerance pathways of nuclear-Ag-specific HKIR B cells that regulate autoantibody production. Our published and preliminary data indicate that peripheral B cell tolerance operative in the AFC and GC pathways can be altered in the presence of lupus susceptibility locus Sle1. However, the influence of Sle1 on the AFC and GC-memory tolerance appeared to be incompletely penetrant indicating the possible requirement of defects in T and/or myeloid compartments for such loss of peripheral B cell tolerance leading to production of IgG ANAs and development of lupus. Here, we propose to identify the susceptibility gene(s) within the Sle1 locus that drive B cell development into AFC and GC pathways leading to loss of peripheral B cell tolerance (Aim-1). In Aim-2, we will determine the cell type (T and/or DCs) affected by the susceptibility gene(s) within the Sle3 interval that provides B cell help and thus promotes a break in GC tolerance. In Aim-3, we will study how type I IFNs (IFN-1) may accelerate the process of a break in GC-memory tolerance and permits robust autoantibody production in lupus-prone mice. PUBLIC HEALTH RELEVANCE: Completion of the proposed studies will provide important new insights into the role of peripheral self-tolerance operative during the AFC and GC-memory pathways in silencing autoantibody production. These studies will also facilitate our understanding of how perturbations in these pathways due to the presence of lupus susceptibility loci lead to the development of autoantibody production and autoimmune disease lupus.