Genetic, Viral and Immunlogic Studies in New Zealand Mice

描述（由申请人提供）：我们的总体目标是了解为什么SLE（狼疮）的免疫系统对来自生理程序性凋亡细胞的核自身抗原有异常反应，以及这种反应如何被特异性下调以获得有效治疗？我们发现狼疮的自身免疫T细胞和B细胞识别来自核小体的某些关键组蛋白肽表位/s，这在低剂量耐受性方案中通过诱导强效调节性T细胞（Treg）亚群来阻断狼疮的发病和进展。诱导的Treg细胞抑制自身免疫性辅助性T细胞（Th）、B细胞和自身抗原呈递细胞（APC），以及狼疮肾脏和血管中的炎症细胞浸润。这种疗法在SNF1小鼠自发性SLE中产生耐受性浆细胞样树突状细胞（pDC），引起自身抗原特异性Treg细胞的扩增和自身免疫和炎症性Th1和Th17细胞的收缩。我们提出定义细胞表面和细胞内部的分子变化，导致耐受性pDC中TGF21增加和IL-6表达程序降低。我们还将设计一种体外诱导狼疮小鼠细胞低剂量肽耐受性的培养系统，用于确定toll样受体（TLR）和其他耐受性机制中的信号，并用于将来筛选狼疮患者的耐受性肽。其次，尽管来自凋亡细胞的核抗原参与狼疮自身免疫Th细胞和B细胞之间的同源相互作用，导致致病性抗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B细胞，自身免疫CD4+ Th细胞需要被apc初始激活（引物），apc呈自身抗原颗粒，如来自凋亡细胞的核小体和核糖核蛋白复合物。我们发现，在狼疮易感SNF1小鼠的脾细胞中，CD117+细胞比常规apc （B细胞、DC细胞和巨噬细胞）更有效地呈现凋亡的核自身抗原颗粒，同时激活自身免疫Th1和Th17细胞。CD117 （c-Kit）是一种干细胞因子受体，是巨噬细胞/DC祖细胞（MDP）、DC前体细胞（CDP）和肥大细胞表达的标志物。因此，我们需要确定新的CD117+ apc属于哪个细胞谱系。我们还将研究新型APC在狼疮和其他自身免疫性疾病中破坏B细胞和T细胞耐受性的作用，鉴定它们可能具有的其他独特标记，并研究它们在狼疮中呈递核自身抗原以激活Th1和Th17细胞的异常能力的分子要求。因此，我们的假设和后续目标集中在抗原呈递细胞（APCs）上，以确定新型APCs如何启动对凋亡细胞核抗原耐受性的破坏，从而在狼疮中同时诱导致病性Th1和Th17反应，以及如何阻断这一启动步骤；反过来，其他apc如pDC如何在狼疮抗原特异性耐受治疗后恢复免疫调节。公共卫生相关性：我们已经发明并开发了一种针对自身免疫细胞的无毒、抗原特异性耐受性治疗，使SLE或狼疮患者免于接受诱变细胞毒性药物、皮质类固醇和全局免疫抑制剂。该疗法还旨在维持狼疮患者的缓解期，并防止高危患者器官损害疾病的发生或进展。在本应用中，我们将定义该疗法如何恢复狼疮免疫系统的正常调节，以及如何进一步改善。对其机制的详细了解将使这种疗法迅速应用于临床。这些研究还将更好地定义由一种新的抗原呈递细胞诱导的自身免疫反应引发的疾病发病机制，不仅在狼疮中，而且在其他自身免疫性炎症疾病中，如类风湿关节炎、多发性硬化症和胰岛素依赖性糖尿病中。总的来说，这些疾病影响了数以千万计的美国人，造成了相当大的发病率（疾病）、死亡率（死亡）、痛苦和医疗费用。这些研究将有助于设计特定的方法来阻止主要自身免疫性疾病中耐受性破坏的最初步骤。

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.