title: Oxidative stress-induced premature senescence dysregulates VEGF and CFH expression in retinal pigment epithelial cells: Implications for Age-related Macular Degeneration.
abstract: Oxidative stress has a critical role in the pathogenesis of Age-related Macular Degeneration (AMD), a multifactorial disease that includes age, gene variants of complement regulatory proteins and smoking as the main risk factors. Stress-induced premature cellular senescence (SIPS) is postulated to contribute to this condition. In this study, we hypothesized that oxidative damage, promoted by endogenous or exogenous sources, could elicit a senescence response in RPE cells, which would in turn dysregulate the expression of major players in AMD pathogenic mechanisms. We showed that exposure of a human RPE cell line (ARPE-19) to a cigarette smoke concentrate (CSC), not only enhanced Reactive Oxygen Species (ROS) levels, but also induced 8-Hydroxydeoxyguanosine-immunoreactive (8-OHdG) DNA lesions and phosphorylated-Histone 2AX-immunoreactive (p-H2AX) nuclear foci. CSC-nuclear damage was followed by premature senescence as shown by positive senescence associated-β-galactosidase (SA-β-Gal) staining, and p16(INK4a) and p21(Waf-Cip1) protein upregulation. N-acetylcysteine (NAC) treatment, a ROS scavenger, decreased senescence markers, thus supporting the role of oxidative damage in CSC-induced senescence activation. ARPE-19 senescent cultures were also established by exposure to hydrogen peroxide (H2O2), which is an endogenous stress source produced in the retina under photo-oxidation conditions. Senescent cells upregulated the proinflammatory cytokines IL-6 and IL-8, the main markers of the senescence-associated secretory phenotype (SASP). Most important, we show for the first time that senescent ARPE-19 cells upregulated vascular endothelial growth factor (VEGF) and simultaneously downregulated complement factor H (CFH) expression. Since both phenomena are involved in AMD pathogenesis, our results support the hypothesis that SIPS could be a principal player in the induction and progression of AMD. Moreover, they would also explain the striking association of this disease with cigarette smoking.
authors.affiliation: Cell and Molecular Medicine, Facultad de Ciencias Biomédicas, Universidad Austral, Pilar B1629AHJ, Argentina.
authors.forename: Mariela C
authors.initials: MC
authors.lastname: Marazita
authors.affiliation: Fundación Pablo Cassará, Buenos Aires C1440 FFX, Argentina.
authors.forename: Andrea
authors.initials: A
authors.lastname: Dugour
authors.affiliation: Cell and Molecular Medicine, Facultad de Ciencias Biomédicas, Universidad Austral, Pilar B1629AHJ, Argentina.
authors.forename: Melisa D
authors.initials: MD
authors.lastname: Marquioni-Ramella
authors.affiliation: Fundación Pablo Cassará, Buenos Aires C1440 FFX, Argentina.
authors.forename: Juan M
authors.initials: JM
authors.lastname: Figueroa
authors.affiliation: Cell and Molecular Medicine, Facultad de Ciencias Biomédicas, Universidad Austral, Pilar B1629AHJ, Argentina. Electronic address: amsuburo@austral.edu.ar.
authors.forename: Angela M
authors.initials: AM
authors.lastname: Suburo
mesh_terms: D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D016922:Cellular Senescence / Q000187:drug effects; D017242:Complement Factor H / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D006861:Hydrogen Peroxide / Q000009:adverse effects*; D007378:Interleukins / Q000378:metabolism; D008268:Macular Degeneration / Q000209:etiology / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D018384:Oxidative Stress; D055213:Retinal Pigment Epithelium / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D012906:Smoke / Q000009:adverse effects*; D014026:Nicotiana / Q000737:chemistry; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism*
chemical_list: C493495:CFH protein, human; D007378:Interleukins; D012906:Smoke; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D017242:Complement Factor H; D006861:Hydrogen Peroxide