Department of Ophthalmology, University of Florida, Gainesville, Florida, 32610, USA.
Department of Neuroscience, Center for Translational Research in Neurodegenerative disease and McKnight Brain Institute, University of Florida, Gainesville, Florida, 32610, USA.
Sci Rep. 2017 Jun 12;7(1):3222. doi: 10.1038/s41598-017-03397-2.
Age-related macular degeneration (AMD) is a progressive retinal neurodegenerative disorder characterized by extracellular deposits known as drusen. A major constituent of drusen deposits are Alzheimer disease-associated amyloid β (Aβ) peptides. To understand the etiology of Aβ proteostasis in AMD, we delivered recombinant adeno-associated virus (AAV) encoding Aβ42 and Aβ40 peptides fused to BRI2 protein by intraocular injection in C57BL/6J mice. Endogenous protease cleavage of such constructs leads to production of secreted Aβ42 and Aβ40 respectively. We demonstrate that overexpression of secreted Aβ40 or Aβ42 resulted in dramatic induction of drusen-like deposits by 2 months' post-injection. These drusen-like deposits were immunopositive for Aβ and complement proteins but did not stain for conventional amyloid dyes, such as Thioflavin S. Both injected cohorts showed gliosis and degenerative changes, though ERG responses were minimally affected. Intriguingly, simultaneous overexpression of BRI-Aβ40 or BRI-Aβ42 together resulted in dose-dependent and cumulative changes reminiscent of AMD type pathology - drusen-like deposits, severe reduction in ERG responses, photoreceptor cell loss and gliosis. Here, we have established a physiological model of Aβ containing deposits in wild-type mice that recapitulates major retinal pathophysiological features of AMD and will be instrumental in mechanistic understanding and development of therapeutic strategies against AMD.
年龄相关性黄斑变性(AMD)是一种进行性视网膜神经退行性疾病,其特征是存在称为玻璃膜疣的细胞外沉积物。玻璃膜疣沉积物的主要成分是阿尔茨海默病相关的淀粉样β(Aβ)肽。为了了解 AMD 中 Aβ 蛋白稳态的病因,我们通过眼内注射将编码 Aβ42 和 Aβ40 肽与 BRI2 蛋白融合的重组腺相关病毒(AAV)递送至 C57BL/6J 小鼠中。这些构建体的内源性蛋白酶切割导致分别产生分泌型 Aβ42 和 Aβ40。我们证明,过表达分泌型 Aβ40 或 Aβ42 会导致注射后 2 个月出现明显的类似玻璃膜疣的沉积物。这些类似玻璃膜疣的沉积物免疫阳性反应为 Aβ 和补体蛋白,但不染色常规的淀粉样染料,如硫黄素 S。两个注射组都显示出神经胶质增生和退行性变化,尽管 ERG 反应受到最小影响。有趣的是,BRI-Aβ40 或 BRI-Aβ42 的同时过表达导致类似于 AMD 型病理学的剂量依赖性和累积变化 - 类似玻璃膜疣的沉积物、ERG 反应严重降低、光感受器细胞丢失和神经胶质增生。在这里,我们在野生型小鼠中建立了含有 Aβ 的沉积物的生理模型,该模型重现了 AMD 的主要视网膜病理生理学特征,将有助于对 AMD 的发病机制和治疗策略的开发。