Altered bioenergetics and enhanced resistance to oxidative stress in human retinal pigment epithelial cells from donors with age-related macular degeneration

Abstract

Age-related macular degeneration (AMD) is the leading cause of blindness among older adults. It has been suggested that mitochondrial defects in the retinal pigment epithelium (RPE) underlies AMD pathology. To test this idea, we developed primary cultures of RPE to ask whether RPE from donors with AMD differ in their metabolic profile compared with healthy age-matched donors. Analysis of gene expression, protein content, and RPE function showed that these cultured cells replicated many of the cardinal features of RPE in vivo. Using the Seahorse Extracellular Flux Analyzer to measure bioenergetics, we observed RPE from donors with AMD exhibited reduced mitochondrial and glycolytic function compared with healthy donors. RPE from AMD donors were also more resistant to oxidative inactivation of these two energy-producing pathways and were less susceptible to oxidation-induced cell death compared with cells from healthy donors. Investigation of the potential mechanism responsible for differences in bioenergetics and resistance to oxidative stress showed RPE from AMD donors had increased PGC1α protein as well as differential expression of multiple genes in response to an oxidative challenge. Based on our data, we propose that cultured RPE from donors phenotyped for the presence or absence of AMD provides an excellent model system for studying “AMD in a dish”. Our results are consistent with the ideas that (i) a bioenergetics crisis in the RPE contributes to AMD pathology, and (ii) the diseased environment in vivo causes changes in the cellular profile that are retained in vitro.

Stem cell-derived retinal pigment epithelium from patients with age-related macular degeneration exhibit reduced metabolism and matrix interactions

“…The effects on energy/metabolic pathways led us to analyze mitochondrial function. Consistent with previous reports, we found a decrease in metabolic capacity . All four parameters (mitochondrial basal respiration, ATP production, maximal respiration, and spare respiratory capacity) were significantly lower in cell lines from individuals with AMD compared to normal controls.…”

“…Our microarray array data showed altered gene expression in metabolic‐related pathways (Table ). Furthermore, earlier studies of bioenergetics demonstrate mitochondrial dysfunction in RPE cells from patients with AMD . Therefore, we analyzed mitochondrial function of iPSC‐derived RPE cells using the Seahorse platform .…”

“…Consistent with previous reports, we found a decrease in metabolic capacity. 36,46 All four parameters (mitochondrial basal respiration, ATP production, maximal respiration, and spare respiratory capacity) were significantly lower in cell lines from individuals with AMD compared to normal controls. The reduced metabolic activity may point to why these diseased cells are less able to attach and proliferate on damaged ECM.…”

Loss of Complement Factor H impairs antioxidant capacity and energy metabolism of human RPE cells

“…In fact, energy metabolism of primary RPE cells isolated from AMD patients was found to be strongly impaired compared to RPE cells from healthy controls [9]. In this model, glycolysis as well as mitochondrial respiration were reduced in RPE cells from AMD patients [9]. Other studies showed that mitochondrial dysfunction in RPE cells may represent a relevant AMD feature.…”

“…Ageing processes in combination with external stressors, such as smoking or a high fat diet [7, 8], force RPE cells to deal with excessive levels of oxidative stress. In fact, energy metabolism of primary RPE cells isolated from AMD patients was found to be strongly impaired compared to RPE cells from healthy controls [9]. In this model, glycolysis as well as mitochondrial respiration were reduced in RPE cells from AMD patients [9].…”