Genetic, Viral and Immunlogic Studies in New Zealand Mice

描述(申请人提供)：我们的总体目标是了解为什么SLE(狼疮)中的免疫系统对经历生理性程序性凋亡的细胞的核自身抗原做出异常反应，以及如何特别下调这种反应以进行有效的治疗？我们发现狼疮自身免疫的T和B细胞识别核小体中的某些关键的组蛋白表位/S，在低剂量耐受方案中，这种表位通过诱导强大的调节性T细胞(Treg)亚群来阻止狼疮的发生和发展。诱导的Treg细胞可抑制狼疮患者肾脏和血管中的炎性细胞浸润，抑制自身免疫T辅助细胞(Th)、B细胞和自身抗原提呈细胞(APC)。这种疗法在患有自发性SLE的SNF1小鼠中产生耐受性浆细胞样树突状细胞(PDC)，导致自身抗原特异性Treg细胞的扩张，以及自身免疫性和炎症性Th1和Th17细胞的收缩。我们建议定义细胞表面和细胞内部的分子变化，这些变化导致耐受性PDC中TGF21的增加和IL-6表达的减少。我们还将设计一种利用狼疮小鼠细胞体外诱导低剂量多肽耐受的培养系统，用于确定Toll样受体(Toll-like Receptor，TLR)等耐受机制中的信号，并用于筛选狼疮患者的耐受肽。其次，虽然来源于凋亡细胞的核抗原参与了狼疮自身免疫性Th细胞和B细胞之间的同源相互作用，导致了致病性抗DNA自身抗体的产生，但最初的步骤尚不清楚。为了帮助自身免疫的B细胞，自身免疫的CD4+Th细胞最初需要被APC激活(启动)，APC呈递自身抗原颗粒，如来自凋亡细胞的核小体和核核蛋白复合体。我们发现狼疮易感的SNF1小鼠脾细胞中的CD117+细胞比传统的APC(B细胞、DC和巨噬细胞)更能有效地同时激活自身免疫的Th1和Th17细胞。CD117(c-Kit)是干细胞因子的受体，是巨噬细胞/树突状细胞(MDP)、普通DC前体(CDP)细胞和肥大细胞表达的标志物。因此，我们需要确定新的CD117+APC属于哪一种细胞系。我们还将研究新型APC在打破狼疮和其他自身免疫性疾病中B和T细胞耐受性方面的作用，确定它们可能拥有的其他独特标记，并研究它们呈现核自身抗原以激活狼疮Th1和Th17细胞的不寻常能力的分子要求。因此，我们的假设和后续目标集中在抗原提呈细胞，以确定新的抗原提呈细胞如何启动对核抗原的耐受，从凋亡细胞中同时诱导狼疮患者致病的Th1和Th17反应，以及如何阻断这一启动步骤；反过来，其他抗原提呈细胞，如PDC，如何在狼疮抗原特异性耐受治疗后恢复免疫调节。与公共卫生相关：我们发明并开发了一种针对自身免疫细胞的无毒、抗原特异性耐受疗法，使SLE或狼疮患者免于接受诱变细胞毒剂、皮质类固醇和全球免疫抑制剂。该疗法还旨在维持狼疮患者的缓解期，并防止有风险的患者发生或发展器官损害性疾病。在这项应用中，我们将定义治疗如何恢复狼疮免疫系统的正常调节，以及如何进一步改进。对这些机制的详细了解将迅速将这种治疗方法带到临床上来。这些研究还将为狼疮和其他自身免疫性炎症性疾病，如类风湿性关节炎、多发性硬化症和胰岛素依赖型糖尿病，提供一个更好的定义，疾病的发病机制是由一种新型的抗原提呈细胞引发的自身免疫反应。总体而言，这些疾病影响着数千万美国人，导致相当大的发病率(疾病)、死亡率(死亡)、痛苦和痛苦以及医疗费用。这些研究将有助于设计具体的方法来阻止主要自身免疫性疾病耐受性崩溃的初始步骤。

DESCRIPTION (provided by applicant): Our overall objective is to understand why the immune system in SLE (lupus) responds abnormally to nuclear autoantigens from cells undergoing physiologically programmed apoptosis, and how this response could be specifically downregulated for effective therapy? We have found that autoimmune T and B cells of lupus recognize certain critical histone peptide epitope/s from nucleosomes, which in a low-dose tolerance regimen blocks pathogenesis and progression of lupus by inducing potent regulatory T-cell (Treg) subsets. The induced Treg cells suppress autoimmune T helper (Th) cells, B cells and autoantigen presenting cells (APC), as well as inflammatory cell infiltration in kidneys and blood vessels in lupus. This therapy in SNF1 mice with spontaneous SLE, generates tolerogenic plasmacytoid dendritic cells (pDC) that cause expansion of autoantigen-specific Treg cells and contraction of autoimmune and inflammatory Th1 and Th17 cells. We propose to define molecular changes at the cell-surface and inside the cell that cause an increased TGF21 and decreased IL-6 expression program in the tolerogenic pDC. We will also devise a culture system for inducing low-dose peptide tolerance in vitro using lupus mouse cells to be used for defining toll-like receptor (TLR) and other signals in tolerance mechanisms, and for future application to screen tolerogenic peptides in lupus patients. Secondly, although nuclear antigens derived from apoptotic cells participate in cognate interactions between autoimmune Th cells and B cells in lupus leading to production of pathogenic anti-DNA autoantibodies, the initial steps are not known. In order to give help to autoimmune B cells, autoimmune CD4+ Th cells are required to be initially activated (primed) by APCs which present autoantigen particles, such as nucleosomes and ribonuclear protein complex from apoptotic cells. We have found that CD117+ cells in splenocytes of lupus-prone SNF1 mice present apoptotic nuclear autoantigen particles much more efficiently than conventional APCs (B cells, DC and Macrophages) to activate autoimmune Th1 and Th17 cells simultaneously. CD117 (c-Kit), a receptor for stem cell factor, is a marker expressed by macrophage/DC progenitor (MDP) cells, common DC precursor (CDP) cells, and mast cells. Therefore, we need to identify which lineage of cells the novel CD117+ APCs belong. We will also study the role of the novel APC in breaking B and T cell tolerance in lupus and other autoimmune diseases, identify other unique markers they may have, and study the molecular requirements for their unusual ability to present nuclear autoantigens to activate both Th1 and Th17 cells in lupus. Thus, our hypotheses and ensuing aims are focused on antigen presenting cells (APCs), to determine how novel APCs initiate breakdown of tolerance to nuclear antigens from apoptotic cells to induce pathogenic Th1 and Th17 responses simultaneously in lupus and how this priming step can be blocked; and conversely how other APCs, such as pDC can restore immunoregulation after antigen specific tolerance therapy of lupus. PUBLIC HEALTH RELEVANCE: We have invented and developed a non-toxic, antigen-specific tolerance therapy targeted against autoimmune cells that would spare SLE or lupus patients from receiving mutagenic cytotoxic agents, corticosteroids and global immunosuppressants. The therapy is also aimed at maintaining lupus patients in remission, and preventing the initiation or progression of organ damaging disease in patients at risk. In this application we will define how the therapy works to restore normal regulation of the immune system in lupus, and how it can be improved further. A detailed understanding of the mechanisms would rapidly bring this therapy to patients in the clinic. The proposed studies will also provide a better definition disease pathogenesis initiated by a novel antigen-presenting cell inducing autoimmune response in not only lupus, but also other autoimmune inflammatory diseases, such as rheumatoid arthritis, multiple sclerosis, and insulin-dependent diabetes mellitus. Collectively, these diseases affect tens of millions of Americans, resulting in considerable morbidity (sickness), mortality (death), pain and suffering, and medical costs. The studies would help in devising specific means to block the initial steps of tolerance breakdown in major autoimmune diseases.