Membrane complement regulators in RPE degeneration and retinal injury

说明(申请人提供)：补体是先天免疫的一种重要形式，在宿主防御中起着关键作用。然而，最近的研究表明，它也与许多人类疾病有关，既有罕见的，也有常见的。与补体激活异常有关的高发疾病之一是老年性黄斑变性(AMD)，这是一种老年人的进行性失明疾病。遗传学研究表明，补体基因如补体因子H(Fh)、因子B(Fb)、成分2(C2)和成分3(C3)携带单核苷酸多态性(SNP)的个体患AMD的风险增加。虽然已经建立了小鼠模型来研究补体在以脉络膜新生血管(CNV)为终点的湿性AMD中的作用，几种抗补体药物正在进行湿性AMD的临床试验，但需要更好地了解补体在干性AMD发展中的作用，并将通过动物模型的开发来帮助。RPE功能障碍是干性和湿性AMD相互重叠的病理原因。在这个项目中，我们将在眼内补体激活异常的背景下研究RPE功能障碍和视网膜损伤的发病机制。我们通过选择性地删除RPE细胞中的一个关键的膜补体调节因子CRY来创建一个小鼠模型。CRY是一种小鼠C3转换酶抑制剂，被认为是人膜辅因子蛋白(MCP，CD46)的功能同源物。CD46在扩张性地理萎缩(GA)区域的RPE中下调，使其成为与疾病相关的靶点。通过使用cre-lox条件基因打靶策略，我们选择性地灭活了RPE细胞中的CRY基因，模拟了GA中CD46的丢失。RPE特异性Crry基因敲除(KO)小鼠的初步特征显示了局部补体激活以及类似于人类干性AMD的RPE变性特征。此外，突变小鼠出现了视网膜色素沉着和视网膜神经感觉性功能障碍。因此，RPE特异的Crry KO小鼠代表了一种新的动物模型，该模型发展了补体介导的具有干性AMD特征的RPE变性/沉积。这项建议的总体目标是使用RPE特异性的Crry KO小鼠，研究调节失调的补体在视网膜变性发病机制中的作用机制，确定负责的补体介质，并探索针对这种疾病的抗补体治疗方法。这些研究将有助于指导未来关于有效补体的抗补体临床试验 层叠的管理目标和途径。

DESCRIPTION (provided by applicant): Complement is an important form of innate immunity that plays a key role in host defense. However, recent studies have revealed that it is also implicated in many human diseases, both rare and common. One of the high-prevalence diseases that have been linked to abnormal complement activation is age-related macular degeneration (AMD), a progressive blinding condition in the elderly. Genetic studies have provided evidence that individuals carrying single nucleotide polymorphism (SNP) in complement genes such as complement factor H (fH), factor B (fB), component 2 (C2) and component 3 (C3) are at increased risk of developing AMD. Although mouse models have been developed to study the role of complement in wet AMD with choroidal neovascularization (CNV) as an endpoint, and several anti-complement agents are being evaluated in clinical trials for wet AMD, better understanding of the role of complement in the development of dry AMD is required, and will be aided by development of animal models. RPE dysfunction is an overlapping pathological cause for both dry and wet AMD. In this project, we will study the pathogenesis of RPE dysfunction and retinal injury in the context of abnormal complement activation in the eye. We have created a mouse model by selectively deleting a key membrane complement regulator Crry in RPE cells. Crry is a murine C3 convertase inhibitor that is considered a functional homolog of human membrane cofactor protein (MCP, CD46). CD46 is down- regulated in the RPE in regions of expanding geographic atrophy (GA), making it a disease-relevant target. By using the cre-lox conditional gene targeting strategy, we selectively inactivated the Crry gene in RPE cells, modeling loss of CD46 in GA. Preliminary characterization of the RPE-specific Crry knockout (KO) mice revealed local complement activation together with features of RPE degeneration akin to human dry AMD. Furthermore, the mutant mice developed sub-RPE deposits and neurosensory retinal dysfunction. The RPE- specific Crry KO mouse thus represents a novel animal model that develops complement-mediated RPE degeneration/deposits with features of dry AMD. The overall objective of this proposal is to use the RPE- specific Crry KO mouse and investigate the mechanism of action of dysregulated complement in the pathogenesis of retinal degeneration, to define the complement mediators responsible and to explore anti- complement therapies for this disorder. These studies will help guide future anti-complement clinical trials with respect to effective complement cascade targets and routes of administration.