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

项目总结/摘要 血-视网膜屏障（BRB）通过限制溶质和免疫细胞的外渗以及 为所需的营养素和激素提供主动运输机制。BRB功能障碍与 视网膜疾病，包括糖尿病性视网膜病、脉络膜新生血管形成、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Coat病。 虽然经典Norrin和WNT 7A/B信号在诱导和维持血液-CNS系统中的关键作用是通过调节神经元的表达来实现的。 已经鉴定出了屏障，这些途径的高效和治疗上可行的激动剂， 缺乏促进或恢复BRB功能。Norrin的信号启动需要受体Frizzled 4（FZD 4） 以及两种辅助受体，低密度脂蛋白受体相关蛋白5（LRP 5）和四跨膜蛋白-12（TSPAN 12）。 在这里，我们使用一种全新的激动剂来激活典型的（即，β-连环蛋白依赖性）信号转导 内皮细胞激动剂是功能上模拟Norrin和WNT 7 A/B的人抗体形式。的 其作用机制及其在不同类型的BRB缺陷中的功效尚不清楚。我们将进行基于细胞的 实验来测试激动剂通过诱导复合物形成来激活信号传导的假设， 受体和辅助受体分子。要了解哪些类型的BRB缺陷可以通过 激动剂，我们将使用具有不同特征的BRB缺陷的多个小鼠模型。我们将 确定在每个模型中恢复BRB的功效，进行转录组学实验和免疫- 组织化学分析以鉴定BRB恢复机制，并量化血管密度。BRB缺陷， 例如，在一个实施例中，在黄斑水肿中，用抗VEGF或抗炎药物治疗。然而，抗VEGF疗法 并非对所有患者都有效，其他患者可能会产生耐药性。这里使用的新型激动剂具有 与抗VEGF和抗炎药物相比，具有完全不同的药效学特征。因此有 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.