MECHANISMS OF AUTOIMMUNITY IN SLE

描述(由申请人提供)： 摘要系统性红斑狼疮(SLE)是一种典型的自身免疫性疾病，其特征是产生抗核抗体(ANA)并伴有多系统炎症表现。这些抗体针对广泛的核大分子，部分通过形成促进炎症和组织损伤的免疫复合体来介导疾病。虽然针对核小体及其DNA和组蛋白成分的抗体是SLE的最大特征，但针对RNA和RNA结合蛋白的抗体可能表现出类似的致病特性。体内和体外实验表明，核抗原包括DNA、RNA和高迁移率族蛋白1(HMGB1)，具有警示活性。Alarmins代表内源性分子，可以从激活和死亡的细胞中释放出来，并可以刺激先天免疫。一旦转移到细胞外环境，核抗原可以刺激Toll样受体(TLRs)、非TLR核酸传感器以及与免疫复合体其他成分结合的受体。由于它们的警报活性，核分子在疾病中至少可以扮演三个角色：1)由自身抗原特异性B和T细胞驱动抗核抗体的产生；2)作为自身佐剂刺激免疫细胞激活；3)形成沉积在组织中并引发炎症的免疫复合体。鉴于这些作用，以免疫相关的形式释放或暴露核抗原是发病机制中的关键步骤。为了阐明核抗原从细胞中的释放、其物理化学性质及其信号活性，我们建议在体内和体外模型中研究这些问题。具体地说，我们将探索在微粒背景下，核分子作为自身佐剂和自身抗原的作用。微粒子是一种小的膜结合囊泡，像警报一样，从激活或死亡的细胞中释放出来，并显示出免疫刺激活性。1)阐明DNA、RNA和HMGB1在细胞激活和死亡过程中的体内和体外释放，确定其在可溶性和颗粒状中的相对分布；2)评价微粒子的抗原性及其在自身免疫小鼠体内形成免疫复合物的能力。这些研究将确定含有核酸的复合体是否由微粒组成；以及3)确定微粒的免疫活性，确定DNA和RNA对其刺激巨噬细胞和树突状细胞的能力的贡献。这些实验还将探索新型阳离子聚合物来阻断这些反应。这些实验的成功完成将为了解微粒子形式的核分子在SLE中的致病作用提供新的见解，并提供新的生物标志物和潜在的治疗靶点。 公共卫生相关性： 项目简介这些研究通过解决自身免疫性疾病发病机制中的关键问题，与退伍军人的健康相关。与其他自身免疫性疾病一样，随着军队中女性人数的增加，系统性红斑狼疮的频率也在增加。通过阐明细胞外核分子在形成致病免疫复合体中的作用，这些研究将为SLE的炎症和自身反应机制提供新的见解。这些研究可以基于对微粒数量和表型的评估，为自身免疫性疾病提供新的生物标记物。最后，我们对微粒免疫特性的研究可以确定在自身免疫中工作的新信号通路，从而允许开发更有效的免疫抑制剂来改善结果并减轻退伍军人的医疗负担。

DESCRIPTION (provided by applicant): Abstract Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease characterized by the production of antinuclear antibodies (ANA) in association with multisystem inflammatory manifestations. These antibodies target a wide array of nuclear macromolecules and mediate disease in part by the formation of immune complexes that promote inflammation and tissue damage. While antibodies to nucleosomes and its DNA and histone components are the most characteristic of SLE, antibodies to RNA and RNA binding proteins may display similar pathogenetic properties. As shown in in vivo and in vitro experiments, nuclear antigens, including DNA, RNA and the high mobility group protein 1 (HMGB1), have activity as alarmins. Alarmins represent endogenous molecules that can be released from activated as well as dying cells and can stimulate innate immunity. Once they translocate into the extracellular milieu, nuclear antigens can stimulate toll-like receptors (TLRs), non-TLR nucleic acid sensors as well as receptors binding other components of the immune complexes. Because of their alarmin activity, nuclear molecules can play at least 3 roles in disease: 1) drive the production of antinuclear antibodies by autoantigen-specific B and T cells; 2) function as autoadjuvants to stimulate immune cell activation; and 3) form immune complexes that deposit in the tissue and incite inflammation. In view of these roles, the release or exposure of nuclear antigens in an immunologically relevant form is a key step in pathogenesis. To elucidate the release of nuclear antigens from cells, their physical-chemical properties and their signaling activity, we propose investigating these issues in in vivo and in vitro models. Specifically, we will explore the role of nuclear molecules as autoadjuvants and autoantigens in the context of microparticles. Microparticles are small membrane-bound vesicles which, like alarmins, are released from activated or dying cells and display immunostimulatory activity. Three specific aims are proposed: 1) To elucidate the in vivo and in vitro release of DNA, RNA and HMGB1 during activation and cell death, determining the relative distribution in soluble and particulate form; 2) To assess the antigenic properties of microparticles and their ability to form immune complexes in vitro and in vivo in autoimmune mice. These studies will determine whether complexes containing nucleic acids are comprised of microparticles; and 3) To define the immunological activity of microparticles, determining the contribution of DNA and RNA to their ability to stimulate macrophages and dendritic cells. These experiments will also explore novel cationic polymers to block these responses. Successful completion of these experiments will provide new insights in the pathogenic role in SLE of nuclear molecules in the form of microparticles as well as provide new biomarkers and potential targets of therapy. PUBLIC HEALTH RELEVANCE: Project Narrative These studies are relevant to the health of veterans by addressing key issues in the pathogenesis of autoimmune disease. Like other autoimmune diseases, SLE is growing in frequency as the number of women in the military increases. By elucidating the role of extracellular nuclear molecules in forming pathogenic immune complexes, these studies will provide new insights into the mechanisms of inflammation and autoreactivity in SLE. These studies could suggest new biomarkers for autoimmune diseases based on assessing microparticle number and phenotype. Finally, our studies on the immune properties of microparticles could identify new signaling pathways operating in autoimmunity, allowing the development of more effective immunosuppressive agents to improve outcomes and reduce the burden of health care in the veteran population.