Complement Factor H Loss in RPE Cells Causes Retinal Degeneration in a Human RPE-Porcine Retinal Explant Co-Culture Model.

Angela Armento,Ellen Kilger,Simon J Clark,Blanca Arango-Gonzalez,Julia Marzi,Jason C Steel,Charmaine A Ramlogan-Steel,Marius Ueffing,Katja Schenke-Layland,Ana C Almansa-Garcia,Aparna Murali

doi:10.3390/biom11111621

Abstract

Age-related Macular degeneration (AMD) is a degenerative disease of the macula affecting the elderly population. Treatment options are limited, partly due to the lack of understanding of AMD pathology and the lack of suitable research models that replicate the complexity of the human macula and the intricate interplay of the genetic, aging and lifestyle risk factors contributing to AMD. One of the main genetic risks associated with AMD is located on the Complement Factor H (CFH) gene, leading to an amino acid substitution in the Factor H (FH) protein (Y402H). However, the mechanism of how this FH variant promotes the onset of AMD remains unclear. Previously, we have shown that FH deprivation in RPE cells, via CFH silencing, leads to increased inflammation, metabolic impairment and vulnerability toward oxidative stress. In this study, we established a novel co-culture model comprising CFH silenced RPE cells and porcine retinal explants derived from the visual streak of porcine eyes, which closely resemble the human macula. We show that retinae exposed to FH-deprived RPE cells show signs of retinal degeneration, with rod cells being the first cells to undergo degeneration. Moreover, via Raman analyses, we observed changes involving the mitochondria and lipid composition of the co-cultured retinae upon FH loss. Interestingly, the detrimental effects of FH loss in RPE cells on the neuroretina were independent of glial cell activation and external complement sources. Moreover, we show that the co-culture model is also suitable for human retinal explants, and we observed a similar trend when RPE cells deprived of FH were co-cultured with human retinal explants from a single donor eye. Our findings highlight the importance of RPE-derived FH for retinal homeostasis and provide a valuable model for AMD research.

Highlights

Age-related macular degeneration (AMD) is a complex multifactorial disease that severely compromises visual acuity and eventually leads to irreversible blindness if left untreated [1,2]
This study aimed to evaluate whether and how retinal pigment epithelium (RPE) cells deprived of Factor H (FH) affect homeostasis of the neuroretina
We used a co-culture system comprising human hTERT-RPE1 cells and porcine retinal explants obtained from the porcine visual streak cone-rich area to study the impact of those impaired RPE cells on the retina. hTERT-RPE1 cells were either silenced for the Complement Factor H (CFH) gene or treated by an siRNA negative control; (Figure S2B–D)

Summary

Introduction

Age-related macular degeneration (AMD) is a complex multifactorial disease that severely compromises visual acuity and eventually leads to irreversible blindness if left untreated [1,2]. It is the leading cause of blindness among the elderly population globally, and the numbers are expected to increase due to the increasing aged population [3]. A lack of macula-like research models makes it very difficult to investigate the order of events in AMD pathology. It is unclear whether rod or cone PR die first and, most importantly, the mechanism behind the cell death of either one of them.

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