Investigation of a first-in-class Frizzled4/LRP5 agonist in retinal disease models

项目摘要/摘要 血-视网膜屏障(BRB)通过限制溶质和免疫细胞的外溢以及通过 为所需的营养物质和激素提供主动的运输机制。BRB功能障碍与 视网膜疾病包括糖尿病视网膜病变、脉络膜新生血管、视网膜阻塞性疾病、葡萄膜炎、 黄斑毛细血管扩张症、家族性渗出性玻璃体视网膜病变、早产儿视网膜病变和科特氏病。 尽管规范的Norrin和WNT7A/B信号在诱导和维持血液中枢神经系统中的关键作用 已经确定了这些通路的高效力和可治疗的激动剂的屏障，它们可以 缺乏促进或恢复BRB功能。去甲肾上腺素的信号启动需要受体Frizzled4(FZD4) 和两个辅助受体，低密度脂蛋白受体相关蛋白5(LRP5)和TSPAN12(TSPAN12)。 在这里，我们使用一种全新的激动剂来激活典型的(即，β-连环蛋白依赖的)信号传导。 内皮细胞。激动剂是一种人类抗体形式，在功能上模仿Norrin和WNT7A/B。 不同类型的BRB缺陷的作用机制和疗效尚不清楚。我们将进行基于细胞的 验证激动剂通过诱导复合体的形成来激活信号的假设的实验 受体和共受体分子。要了解哪些类型的BRB缺陷可以通过 激动剂，我们将使用多种具有不同特征的BRB缺陷的小鼠模型。我们会 确定每种模型修复BRB的效果，进行转录实验和免疫学实验 组织化学分析以确定BRB修复的机制，并量化血管密度。BRB缺陷， 例如，在黄斑水肿时，使用抗血管内皮生长因子或抗炎药物治疗。然而，抗血管内皮生长因子疗法 并不是对所有患者都有效，其他患者可能会产生耐药性。这里使用的新型激动剂有一种 与抗血管内皮生长因子和抗炎药相比，其药效学特征完全不同。因此，它是 重要的是评估这种候选药物的治疗潜力。

PROJECT SUMMARY/ABSTRACT The blood-retina barrier (BRB) protects the retina by limiting extravasation of solutes and immune cells and by providing active transport mechanisms for required nutrients and hormones. BRB dysfunction is implicated in retinal diseases including diabetic retinopathy, choroidal neovascularization, retinal occlusive diseases, uveitis, macular telangiectasia, familial exudative vitreoretinopathy, retinopathy of prematurity, and Coat’s disease. Although the key role of canonical Norrin and WNT7A/B signaling in inducing and maintaining blood-CNS barriers has been identified, highly potent and therapeutically amenable agonists of these pathways that could promote or restore BRB function are lacking. Signal initiation by Norrin requires the receptor Frizzled4 (FZD4) and two co-receptors, low-density-lipoprotein receptor-related protein 5 (LRP5) and tetraspanin-12 (TSPAN12). Here, we use an entirely novel agonist to activate canonical (i.e., beta-catenin-dependent) signaling in endothelial cells. The agonist is a human antibody modality that functionally mimics Norrin and WNT7A/B. The mechanism of action and its efficacy in distinct types of BRB defects are not known. We will conduct cell-based experiments to test the hypothesis that the agonist activates signaling by inducing complex formation of receptor and co-receptor molecules. To understand which types of BRB defects can be restored by the agonist, we will use multiple mouse models with BRB defects that have distinct characteristics. We will determine the efficacy in restoring the BRB in each model, perform transcriptomic experiments and immuno- histochemical analyses to identify mechanism of BRB restoration, and quantify vascular density. BRB defects, e.g., in macular edema, are treated with anti-VEGF or anti-inflammatory drugs. However, anti-VEGF therapies are not effective in all patients, and other patients may develop resistance. The novel agonist used here has an entirely different pharmacodynamic profile compared to anti-VEGF and anti-inflammatory drugs. Therefore, it is important to evaluate this drug candidate for its therapeutic potential.