Subretinal injection of amyloid-β peptide accelerates RPE cell senescence and retinal degeneration

Abstract

Abstract. Drusen are considered a hallmark characteristic of age-related macular degeneration (AMD). In our previous study, we found that amyloid-β (Aβ) peptide, a component of drusen, induced the cells of the retinal pigment epithelium (RPE; RPE cells) to enter senescence; however, its effects in vivo remain unknown. Thus, the present study was carried out to explore the in vivo effects of Aβ peptide on RPE cell senescence and senescence-associated inflammation in C57BL/6 mice. C57BL/6 mice received a subretinal injection of Aβ(1-42) peptide; on day 7 post-injection, the mice were anesthetized and subjected to whole-body perfusion with 4% paraformaldehyde (PFA) in PBS and the whole eyes were then enucleated. Retinal function was assessed by electroretinography (ERG), and the morphological characteristics of the retina were examined by light and electron microscopy. Fundus autofluorescence (FAF) was examined by confocal scanning laser ophthalmoscopy (cSLO). The expression of p16INK4a , a marker of cellular senescence, was examined by immunofluorescence staining and western blot analysis. The RPE-choroid was analyzed for cytokine expression by RT-PCR. In Aβ(1-42)-injected mice, scotopic ERG responses declined. Degenerative alterations, including the disruption of the inner segment (IS)/outer segment (OS) junction and extensive vacuolation and thickness of Bruch's membrane (BrM) were observed under a a light microscope. The accumulation of vacuoles and the loss of basal infoldings in the RPE were identified using an electron microscope. FAF and p16INK4a expression increased in Aβ(1-42)-injected mice. In addition, Aβ(1-42) upregulated interleukin (IL)-6 and IL-8 gene expression in the RPE-choroid. In conclusion, our results confirm the effects of Aβ(1-42) peptide on RPE senescence in vivo. The Aβ-injected mice developed AMD-like ocular pathology. It is thus suggested that RPE cell senescence is a potential mechanistic link between inflammation and retinal degeneration.

One protein, multiple pathologies: multifaceted involvement of amyloid β in neurodegenerative disorders of the brain and retina

“…Both soluble and oligomerised amyloid assemblies have been detected in drusen and RPE of human donor retinas [31]. Sub-retinal administration of Ab42 in mice produced AMD-like symptoms manifested by decline in ERG amplitudes, RPE and photoreceptor degeneration including extensive vacuolation and BrM degeneration further highlighting its pathological involvement [32]. Collectively, these findings point towards a possible association of Ab with AMD pathogenesis.…”

MicroRNA Expression Patterns Involved in Amyloid Beta–Induced Retinal Degeneration

“…For the selection of the drug supply, most similar experiments adopted intravitreal 10,35,38 or subretinal 15,39,40 injection of Ab instead of intravenous injection. Intravitreal or subretinal injection can stimulate local pathogenesis to AMD more effectively than intravenous injection.…”

Parainflammation, chronic inflammation, and age-related macular degeneration

“…Many of the age-induced immune geneexpression changes identified in the array studies have also been observed in vitro. Treatment of RPE cells with the age-related DAMPs, such as AGEs [103], amyloid-b [112][113][114], or oxidized photoreceptor outer segments [98,99], induces the upregulation of proinflammatory genes, such as CCL2, IL-6, TNF-a, and CFB but also reduces immune-regulatory genes (such as CFH [98]). The SASP is a well-known phenomenon in all senescent cells [48].…”