Amyloid β peptides overexpression in retinal pigment epithelial cells via AAV-mediated gene transfer mimics AMD-like pathology in mice

Abstract

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.Age-related macular degeneration (AMD) is a late-onset, progressive retinal neurodegenerative disease and the leading cause of severe and irreversible vision loss in the elderly in developed countries [1][2][3][4][5] . This disease primarily affects the macular region of human retina, which is crucial for central vision and perception of finer details, resulting in a progressive loss of high-resolution central vision in people afflicted with this disorder. The visual impairment associated with AMD occurs as a consequence of two different forms of the disease-dry AMD (geographical atrophy or nonexudative AMD), which is characterized by progressive retinal degeneration involving the photoreceptors and the retinal pigment epithelial (RPE) cells, or the more severe form-wet AMD (choroidal neovascularization or exudative AMD), which is characterized by the growth of new blood vessels from the choroid into the neural retina causing photoreceptor degeneration 2,6,7 . While wet AMD can be treated by laser photocoagulation, photodynamic therapy and intravitreal injections of anti-vascular endothelial growth factor (VEGF)-A and other angiogenic inhibitors, there is no effective treatment available currently for dry AMD 5,[8][9][10] . AMD is clinically characterized by the presence of extracellular deposits known as drusen located between the retinal pigment epithelium (RPE) and Bruch's membrane (sub-RPE) in the macular region. Drusens are also observed in the normal aging eye, however the presence of large drusens in high numbers in the macular region has been identifi...

Neutrophils homing into the retina trigger pathology in early age-related macular degeneration

“…The number of drusen-like sub-retinal deposits were counted in a masked fashion from hematoxylin-eosin images of 12 month old Cryba1 f l/fl , vehicle-treated Cryba1 cKO and AKT2 inhibitor-treated Cryba1 cKO mice retinae respectively. Quantification of drusen-like sub-retinal deposits were done from these images by using the ImageJ/NIH image analysis system in a masked fashion 75 .…”

Eucalyptol Inhibits Amyloid-β-Induced Barrier Dysfunction in Glucose-Exposed Retinal Pigment Epithelial Cells and Diabetic Eyes

“…A potential relationship between Aβ-derived neurotoxins and retinal degeneration has been implicated in diabetes as well as aging and Alzheimer’s disease [ 21 ]. Aβ is found within RPE cells and in extracellular drusen deposits present between the RPE and Bruch’s membrane [ 22 , 23 ]. The accumulation of Aβ peptide in retina is responsible for the development of retinal cell apoptosis [ 24 ].…”

Inhibition of AMD-Like Pathology With a Neurotrophic Compound in Aged Rats and 3xTg-AD Mice

“…Previous studies showed both tau and Aβ pathologies in the retina of 14 m Tg2576 mice (Liu et al, 2009; Hart et al, 2016) and APP immunoreactivity in the retina in a number of AD animal models, including Tg mouse models (hTgAPP tg/tg , APP SWE /PS1 ΔE9 , and APP SWE /PS1 M146L/L286V ) that exhibit several features of AD (Frederikse and Ren, 2002; Ning et al, 2008; Dutescu et al, 2009; Zhao et al, 2013; Du et al, 2015). Moreover, several studies found Aβ deposition in the drusen or retinal layers in AMD animal models (Crabb et al, 2002; Prasad et al, 2017). Anti-Aβ immunotherapy was reported to reduce ocular Aβ deposits in a mouse model of AMD (Ding et al, 2011).…”