Gene-Environment Collaboration in Autoimmune Disease

吸入二氧化硅与几种人类自身免疫性疾病有关，包括全身性 红斑狼疮和ANCA血管炎，破坏肾脏、肺和其他器官。然而，几乎没有什么是 了解自身免疫诱导的机制或遗传易感性的作用。自身抗体 在这些疾病中是突出的，也是组织损伤的关键媒介。这里提出的实验测试了 最重要的假设是，接触二氧化硅的肺创造了一个改变自身免疫细胞的微环境 对遗传易感个体的监管。我们进一步提出，B细胞耐受性的这种突破 通过促进生存的肺第三级淋巴结构或iBALT的中介发生 和自身反应性淋巴细胞的激活，以及人类HLADRB1*1501风险等位基因和Toll样蛋白 受体配体的共同暴露导致了这种破坏。这一假说可以用活体模型进行检验。 允许复杂和动态的免疫细胞在环境/肺界面上相互作用，这是 易受机械解剖的。我们提出了三个具体目标，并得到了广泛的初步支持 数据和已建立的跨学科协作。特定目标1测试了硅石- 诱导性iBALT是B细胞耐受性丧失的主要部位，iBALT形成的程度和性质 缺陷耐受性因遗传易感性而异。我们将衡量招聘和 接尘工人iBALT和次级淋巴器官中自身反应性B细胞的激活 使用流式细胞术、免疫分析、细胞培养和显微解剖。这一目标是可以使用唯一的 以及我们实验室开发的实验上易处理的小鼠模型系统，其中一种自身抗体 转基因是追踪自身反应细胞和监测明确耐受的可靠报告 在遗传上不同的B6和自身免疫性MRL、NZB和BXSB菌株的背景下的表型 共同反映了人类狼疮的遗传异质性。《特定目标2》测试了一个强大的人类的角色 二氧化硅诱导的iBALT诱导和蛋白酶3(PR3)中的自身免疫风险等位基因，人类白细胞抗原II类DRB1*1501。 肛门脉管炎。这个目标使用了两个新的人源化模型，用来取代小鼠的II类分子 人类II类DR2(DRA1/DRB1*1501)。我们将测量二氧化硅暴露对自体反应细胞的影响 DR2+B6自体抗体TG小鼠的募集和耐受及其对抗PR3自身反应性和血管炎的影响 使用在胸腺和人免疫细胞上表达DR2的双重人源化HU-HSC小鼠和 接受PR3免疫或PR3-ANCA输注。特定目标3测试二氧化硅的破碎能力 对髓过氧化物酶(MPO)的耐受性或修改抗MPO免疫和MPO-ANCA血管炎。这一目标 在MRL和MPO缺乏的B6模型中利用MPO免疫反应性和疾病易感性。 最终，对二氧化硅控制的自身免疫机制的洞察将识别新的靶点和新的 自身免疫性疾病患者止伤和预防复发的治疗干预途径。

Inhaled silica has been compellingly linked to several human autoimmune diseases, including systemic lupus erythematosus and ANCA vasculitis that destroy kidneys, lungs, and other organs. However, little is known about the mechanism of autoimmune induction or the role of genetic susceptibility. Autoantibodies are prominent in these disorders and key mediators of tissue injury. The experiments proposed here test the overarching hypothesis that the silica-exposed lung creates a microenvironment that alters autoimmune cell regulation in genetically susceptible individuals. We further propose that this breach in B cell tolerance occurs through the intermediary of pulmonary tertiary lymphoid structures or iBALT that promote survival and activation of autoreactive lymphocytes, and that the human HLA DRB1*1501 risk allele and Toll-like receptor ligand co-exposure contribute to this breach. This hypothesis can be tested using in vivo models that permit complex and dynamic immune cell interactions at the environment/lung interface and that are amenable to mechanistic dissection. We propose three Specific Aims supported by extensive preliminary data and established cross-disciplinary collaborations. Specific Aim 1 tests the hypothesis that silica- induced iBALT is a major site for loss of B cell tolerance, and that the extent and nature of iBALT formation and defective tolerance varies according to genetic susceptibility. We will measure recruitment and activation of autoreactive B cells within iBALT and secondary lymphoid organs of silica-exposed subjects using flow cytometry, immunoassay, cell culture, and microdissection. This aim is possible using a unique and experimentally tractable murine model system developed in our lab, in which an autoantibody transgene serves as a reliable reporter to track autoreactive cells and monitor well-defined tolerance phenotypes within the context of genetically distinct B6 and autoimmune MRL, NZB, and BXSB strains that collectively mirror human lupus genetic heterogeneity. Specific Aim 2 tests the role of a potent human autoimmune risk allele, HLA class II DRB1*1501, in silica-induced iBALT induction and proteinase 3 (PR3)- ANCA vasculitis. This aim uses two novel humanized models that replace murine class II molecules with human class II DR2 (DRA1/DRB1*1501). We will measure silica exposure impact on autoreactive cell recruitment and tolerance using DR2+ B6 autoAb Tg mice, and on anti-PR3 autoreactivity and vasculitis using dual humanized Hu-HSC mice expressing DR2 both in thymus and on human immune cells and subject to PR3 immunization or PR3-ANCA infusion. Specific Aim 3 tests the capacity of silica to break tolerance to myeloperoxidase (MPO) or to modify anti-MPO immunity and MPO-ANCA vasculitis. This aim takes advantage of MPO immunoreactivity and disease-susceptibility in MRL and MPO-deficient B6 models. Ultimately, insight into mechanisms of silica-controlled autoimmunity will identify new targets and new routes for therapeutic intervention to arrest injury and prevent relapses in patients with autoimmune disease.