title: Reduced Metabolic Capacity in Aged Primary Retinal Pigment Epithelium (RPE) is Correlated with Increased Susceptibility to Oxidative Stress.
abstract: One of the affected tissues in age-related macular degeneration (AMD) is the retinal pigment epithelium (RPE), a tissue that consists of terminally differentiated cells and that accumulates damage over time. In all tissues, mitochondria (mt), which play an essential role in both cell health (energy) and death (initiator of apoptosis), undergo an aging process through the accumulation of mtDNA damage, changes in mitochondrial dynamics, a reduction in biogenesis, and mitophagy, leading to an overall reduction in mitochondrial energy production and other non-energy-related functions. Here we have compared energy metabolism in primary human RPE cells isolated from aborted fetus or aged donor eyes and grown as stable monolayers. H2O2 treatment resulted in the generation of reactive oxygen species and superoxide, an effect that was significantly augmented by age. Mitochondrial metabolism, as analyzed by Seahorse respirometry, revealed reduced mitochondrial oxygen consumption (ATP production) at baseline and a complete loss of reserve capacity in aged cells. Likewise, glycolysis was blunted in aged cells. Taken together, these studies showed that RPE cells derived from aged donor eyes are more susceptible to oxidative stress, and exhibit a loss in mitochondrial respiratory reserve capacity and a reduction in glycolysis. These data suggest that while old cells may have sufficient energy at rest, they cannot mount a stress response requiring additional ATP and reducing agents. In summary, these data support the hypothesis that mitochondria or energy metabolism is a valid target for therapy in AMD.
authors.affiliation: Department of Ophthalmology, Medical University of South Carolina, 167 Ashley Ave, SEI614, 29425, Charleston, SC, USA. rohrer@musc.edu.|Research Service, Ralph H. Johnson VA Medical Center, Charleston, SC, USA. rohrer@musc.edu.
authors.forename: Bärbel
authors.initials: B
authors.lastname: Rohrer
authors.affiliation: Department of Ophthalmology, Medical University of South Carolina, 167 Ashley Ave, SEI614, 29425, Charleston, SC, USA.
authors.forename: Mausumi
authors.initials: M
authors.lastname: Bandyopadhyay
authors.affiliation: Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, 167 Ashley Ave, SEI614, 29425, Charleston, SC, USA.
authors.forename: Craig
authors.initials: C
authors.lastname: Beeson
mesh_terms: D000368:Aged; D000375:Aging / Q000378:metabolism*; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D002478:Cells, Cultured; D004734:Energy Metabolism; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D006019:Glycolysis / Q000187:drug effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress; D010101:Oxygen Consumption / Q000187:drug effects; D061251:Primary Cell Culture; D061209:Proton Ionophores / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D055213:Retinal Pigment Epithelium / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism
chemical_list: D016877:Oxidants; D061209:Proton Ionophores; D017382:Reactive Oxygen Species; D013481:Superoxides; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D006861:Hydrogen Peroxide
keywords: ATP production; Mitochondria; Oxidative stress; Retinal pigment epithelium