Membrane complement regulators in RPE degeneration and retinal injury

描述（由申请人提供）：补体是先天免疫的一种重要形式，在宿主防御中起关键作用。然而，最近的研究表明，它也与许多罕见和常见的人类疾病有关。与异常补体激活相关的高患病率疾病之一是年龄相关性黄斑变性（AMD），这是老年人中的一种进行性致盲病症。遗传学研究提供了证据表明，在补体基因如补体因子H（fH）、因子B（fB）、组分2（C2）和组分3（C3）中携带单核苷酸多态性（SNP）的个体处于发生AMD的增加的风险中。虽然已经开发了小鼠模型来研究补体在湿性AMD中的作用，脉络膜新生血管形成（CNV）作为终点，并且在湿性AMD的临床试验中正在评估几种抗补体剂，但是需要更好地理解补体在干性AMD发展中的作用，并且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的重叠病理原因。在这个项目中，我们将研究视网膜色素上皮功能障碍和视网膜损伤的发病机制的背景下，异常补体激活的眼睛。我们已经通过选择性地删除RPE细胞中的关键膜补体调节因子Crry创建了小鼠模型。Crry是一种鼠C3转化酶抑制剂，被认为是人膜辅因子蛋白（MCP，CD 46）的功能同源物。CD 46在扩展地图状萎缩（GA）区域的RPE中下调，使其成为疾病相关靶标。通过使用cre-lox条件基因靶向策略，我们选择性地失活RPE细胞中的Crry基因，模拟GA中的CD 46损失。RPE特异性Crry敲除（KO）小鼠的初步表征揭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，突变小鼠发生了亚RPE沉积和神经感觉视网膜功能障碍。因此，RPE特异性Crry KO小鼠代表了一种新的动物模型，其发展出具有干性AMD特征的补体介导的RPE变性/沉积物。本提案的总体目标是使用RPE特异性Crry KO小鼠并研究调节异常的补体在视网膜变性发病机制中的作用机制，以定义负责的补体介质并探索针对该病症的抗补体疗法。这些研究将有助于指导未来的抗补体临床试验方面的有效补充 级联靶点和给药途径。

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.