The Innate Sensor NLRC3 in the Regulation of Autoreactive B Cells and SLE

描述(申请人提供)：SLE是一种慢性和衰弱的自身免疫性疾病，困扰着150多万美国人，需要终身免疫抑制疗法，具有潜在的生命危险和破坏性副作用。免疫耐受性的丧失是这种疾病的根本，而B细胞在其病因中起着中心作用，这是 强调了B细胞耗竭疗法的有效性。由于并不是所有的患者都能从这种治疗中受益，而且消除B细胞可能会损害患者对病原体的防御，因此只针对自身反应性B细胞的治疗将对患者大有裨益。因此，迫切需要确定免疫耐受的分子机制，因为如果没有它，靶向治疗方法的开发就不太可能发生。我们的初步数据显示，NLRC3是核苷酸结合的亮氨酸重复序列(NLR)家族中的一员，它调节Toll样受体(TLR)介导的自身反应性B细胞的激活。这是一个新的发现，因为NLR家族蛋白I B的功能尚不清楚。我们工作的长期目标是了解B细胞耐受的分子机制，最终目标是开发治疗自身免疫性疾病的靶向疗法。这项建议的目的是确定NLRC3阻断自身反应性B细胞激活的机制，并确定其表达是否影响健康和疾病中的自身反应性B细胞反应。我们的中心假设是，NLRC3抑制TLR介导的自身反应性B细胞激活，以预防自身免疫性疾病。其基本原理是，一旦我们确定了NLRC3的作用机制，就可以开发针对这一机制的新疗法来防止自身反应性B细胞激活。我们提出了两个具体目标。1)确定NLRC3介导的抑制B细胞TLR活化的机制；2)确定NLRC3是否调节正常和致病B细胞对自身抗原的反应。对于目标1，我们将使用NLRC3充足和缺失的原代自身反应B细胞来识别受NLRC3调控的TLR信号中间产物。对于目标2，我们将确定自身抗原激活正常和自身免疫易感小鼠的NLRC3缺陷B细胞的能力，并确定在没有NLRC3的情况下，自身免疫病易感小鼠是否会加速发展为更严重的疾病。我们希望发现NLRC3通过阻止NF-kB和IRF-5转位到细胞核来阻断TLR介导的B细胞激活。此外，我们希望发现NLRC3可以阻止自身反应性B细胞的激活，并减轻自身免疫小鼠疾病的发病和严重程度。在我们看来，这项工作是创新的，因为NLR蛋白参与B细胞耐受构成了一种全新的调节机制。我们的结果将产生重要的积极影响，因为它们可能导致最终开发专门针对耐受性丧失机制的新疗法。

DESCRIPTION (provided by applicant): SLE is a chronic and debilitating autoimmune disease afflicting more than 1.5 million Americans and requires lifelong immunosuppressive therapies that have potentially life-threatening and damaging side effects. The loss of immunological tolerance is fundamental to this disease and B cells are a central player in its etiology, which is underscored by the efficacy of a B cell depletion therapy. Because not all patients benefit from this treatment, and the elimination of B cells can compromise a patient's defenses against pathogens, therapies that target only autoreactive B cells would be of great benefit to patients. Therefore, there is a critical need to identify molecular mechanisms of immune tolerance because without it, the development of a targeted therapeutic approach is unlikely to occur. Our preliminary data shows that NLRC3, a member of the nucleotide-binding, leucine repeat-containing (NLR) family of "danger" sensors, regulates toll like receptor (TLR)-mediated activation of autoreactive B cells. This is a novel finding, as a function of NLR family proteins i B cells is unknown. The long-term goal of our work is to understand the molecular mechanisms of B cell tolerance with the eventual goal of developing targeted therapies for the treatment of autoimmune diseases. The objective of this proposal is to determine the mechanism by which NLRC3 blocks the activation of autoreactive B cells and to determine whether its expression affects autoreactive B cell responses in health and disease. Our central hypothesis is that NLRC3 inhibits TLR- mediated autoreactive B cell activation to prevent autoimmune disease. The rationale is that once we determine the mechanism of action of NLRC3, then new therapies that target this mechanism could be developed to prevent autoreactive B cell activation. We propose two specific aims. 1) To determine the mechanism of NLRC3-mediated inhibition of TLR activation in B cells, and 2) to determine whether NLRC3 regulates normal and pathogenic B cell responses to self-antigens. For Aim 1, we will use we will use primary autoreactive B cells that are NLRC3-sufficient and -deficient to identify the TLR signaling intermediates that are regulated by NLRC3. For Aim 2, we will determine the ability of self-antigen to activate NLRC3-deficient B cells from normal and autoimmune prone mice, and determine whether autoimmune disease prone mice develop accelerated more severe disease in the absence of NLRC3. We expect to find that NLRC3 blocks TLR- mediated B cell activation through its ability to prevent NF-kB and IRF-5 translocation to the nucleus. In addition, we expect to find that NLRC3 prevents autoreactive B cell activation and attenuates the onset and severity of disease in autoimmune mice. This work is innovative in our opinion because NLR protein involvement in B cell tolerance constitutes a completely new regulatory mechanism. Our results will have an important positive impact because they could lead to the eventual development of new therapies designed to specifically target the mechanisms of tolerance loss.