Gene-Environment Collaboration in Autoimmune Disease

吸入二氧化硅与几种人类自身免疫性疾病，包括全身性免疫性疾病， 红斑狼疮和抗中性粒细胞胞浆抗体血管炎，破坏肾脏、肺和其他器官。然而， 了解自身免疫诱导的机制或遗传易感性的作用。自身抗体 在这些疾病和组织损伤的关键介质中是突出的。这里提出的实验测试 总体假设，暴露于二氧化硅的肺创造了一个微环境，改变了自身免疫细胞， 在遗传易感个体中的调节。我们进一步提出，这种B细胞耐受性的破坏 通过促进存活的肺三级淋巴结构或iBALT的中介发生 和自身反应性淋巴细胞的激活，以及人类HLA-DRB 1 *1501危险等位基因和Toll样 受体配体共暴露有助于这种破坏。这一假设可以用体内模型来检验 其允许在环境/肺界面处的复杂和动态的免疫细胞相互作用， 适合机械解剖。我们提出了三个具体目标，并得到广泛的初步支持， 数据和建立跨学科合作。具体目标1测试二氧化硅- 诱导的iBALT是B细胞耐受性丧失的主要部位， 并且缺陷耐受性根据遗传易感性而变化。我们将评估招聘情况， 暴露于二氧化硅的受试者的iBALT和次级淋巴器官内的自身反应性B细胞的活化 使用流式细胞术、免疫测定、细胞培养和显微切割。这一目标是可能的使用一个独特的 在我们实验室开发的实验上易于处理的小鼠模型系统中， 转基因作为一个可靠的报告，跟踪自身反应细胞和监测明确的耐受性 在遗传上不同的B6和自身免疫性MRL、NZB和BXSB菌株的背景下， 共同反映了人类狼疮遗传异质性。具体目标2测试的作用，一个强大的人类 自身免疫风险等位基因，HLA II类DRB 1 *1501，二氧化硅诱导的iBALT诱导和蛋白酶3（PR 3）- ANCA血管炎。该目的使用两种新的人源化模型，其用 人II类DR 2（DRA 1/DRB 1 *1501）。我们将测量二氧化硅暴露对自身反应细胞的影响， 使用DR 2 + B6自身抗体Tg小鼠的募集和耐受性，以及抗PR 3自身反应性和血管炎 使用在胸腺和人免疫细胞上表达DR 2的双重人源化Hu-HSC小鼠， 进行PR 3免疫或PR 3-ANCA输注。具体目标3测试二氧化硅的破碎能力 对髓过氧化物酶（MPO）的耐受性或改变抗MPO免疫和MPO-ANCA血管炎。这一目标 利用MRL和MPO缺陷B6模型中的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深入了解将确定新的靶点和新的治疗方法。 治疗干预的途径，以阻止损伤和预防复发的患者与自身免疫性疾病。

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.