Mechanisms of end organ damage in novel polygenic lupus models

项目摘要 系统性红斑狼疮（SLE）的主要死亡原因是狼疮性肾炎（LN），但其机制尚不清楚。 对肾损伤的原因仍知之甚少。当前LN小鼠模型的局限性在于 遗传原因不完全清楚，或者它们是单基因模型，不能反映多基因的性质 人类SLE的为了产生已知具有免疫途径异常的多基因小鼠模型， 作为SLE的基础，我们产生了凋亡细胞（AC）清除缺陷的小鼠（缺乏MFG-E8）， 补体（C1 q或C3 KO），并产生抗染色质抗体（具有Sle 1间隔）。我们观察到， 只有当所有三种成分一起存在时（三重突变体，TM），小鼠才得LN。非常有趣的是， 缺乏C3的TM对紫外线敏感，并出现慢性皮肤病和全身症状 紫外线照射后。本项目的长期目标是：了解AC的保护作用 调理素MFG-E8在肾脏中的作用;探索补体在肾脏中的保护作用， 致肾炎抗体和AC清除受损;确定TM中肾损伤的效应机制 小鼠和负责紫外线介导的肾脏疾病的机制。 在目标1中，我们将确定双肾与单肾的AC和炎症是否增加。 KO小鼠。我们还将测试MFG-E8是否在肾脏中具有抗炎和抗纤维化作用， 用MFG-E8或MFG-E8条件化巨噬细胞重建小鼠。在目标2中，我们将确定效应器 导致肾损伤的机制。根据初步数据，我们将确认在低C1 q态下， 凝集素途径被DAMPS激活，并试图通过阻断Masp- 2.在我们观察到C5-9形成的低C3状态下，我们将测试替代的C5转化酶是否 由凝血酶产生，并将试图通过抑制实验证明致病性。这些途径将是 在Mfge 8、C1 q、C3缺陷或双敲除（DKO）小鼠中使用均匀肾毒性血清进行验证， 将在来自具有持续低补体的SLE患者的肾脏中进行初步研究。目标3采取 C3 TM小鼠皮肤的UV光暴露导致全身性疾病的观察的优点。我们将 检查这种易感性是否可以通过中性粒细胞释放氧化的线粒体DNA来解释， 或通过炎性细胞从皮肤向肾脏的运输，包括通过逆迁移过程。 总之，使用新的菌株，准确地反映了人类SLE的途径异常，我们将确定 早期补体成分以及调理素（如MFG-E8）是否以及如何保护肾脏。 凝集素途径或凝血酶的参与具有重要的治疗意义， 这些途径中的每一种都是或可以用于人类。确定负责下列方面的机制： UV引发的肾损伤也将导致治疗方法，例如抑制线粒体ROS或线粒体内的氧自由基。 cGAS-STING抑制剂或嗜中性粒细胞逆迁移抑制剂。

Project Summary The major cause of death in systemic lupus erythematosus (SLE) is lupus nephritis (LN) but the mechanisms responsible for kidney damage remain only partly understood. A limitation of current mouse models of LN is that genetic causes are incompletely understood or they are single gene models that don’t reflect the polygenic nature of human SLE. To generate a polygenic mouse model with immune pathway abnormalities that are known to underlie SLE, we generated mice with defects in apoptotic cell (AC) clearance (lack MFG-E8), have low complement (C1q or C3 KO) and that produce anti-chromatin antibodies (have Sle1 interval). We observed that, only when all three components are present together (triple mutants, TM) do mice get LN. Of great interest, the C3 deficient TM was sensitive to UV light and developed chronic skin disease and systemic manifestations following UV exposure. The long-term goals of this project are: to understand the protective role of the AC opsonin, MFG-E8, in the kidney; to explore the protective roles of complement in the kidney under conditions of nephritogenic antibodies and impaired AC clearance; to identify the effector mechanisms of kidney injury in TM mice and the mechanisms responsible for UV mediated kidney disease. In Aim 1, we will determine whether AC and inflammation are increased in the kidneys of double versus single KO mice. We will also test whether MFG-E8 has anti-inflammatory and anti-fibrotic effects in the kidney by reconstituting mice with MFG-E8 or MFG-E8 conditioned macrophages. In Aim 2, we will determine the effector mechanisms responsible for kidney injury. Based on preliminary data, we will confirm that in low C1q states the lectin pathway is activated by DAMPS and will attempt to prove lectin pathway pathogenicity by blocking Masp- 2. In low C3 states where we observed C5-9 formation, we will test whether an alternate C5 convertase is generated by thrombin and will attempt to prove pathogenicity by inhibition experiments. These pathways will be validated using uniform nephrotoxic sera in mice deficient in Mfge8, C1q, C3 or double knock outs (DKO) and pilot studies will be performed in kidneys from SLE patients with persistently low complement. Aim 3 takes advantage of the observation that UV light exposure of skin in C3 TM mice leads to systemic disease. We will examine whether this susceptibility is explained by release of oxidized mitochondrial DNA from neutrophils and/ or by trafficking of inflammatory cells from skin to kidney, including by the process of reverse transmigration. Overall, using novel strains that accurately reflect pathway abnormalities in human SLE, we will determine whether and how early complement components as well as an opsonin such as MFG-E8, protect the kidneys. The involvement of the lectin pathway or thrombin have important therapeutic implications as therapies to block each of these pathways either are, or can be used, in humans. Identification of the mechanisms responsible for UV triggered kidney injury will also lead to therapeutic approaches such as inhibition of mitochondrial ROS or inhibitors of cGAS-STING or inhibitors of neutrophil reverse transmigration.