scholarly journals Oxidative Stress Increases Endogenous Complement-Dependent Inflammatory and Angiogenic Responses in Retinal Pigment Epithelial Cells Independently of Exogenous Complement Sources

Antioxidants ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 548 ◽  
Author(s):  
Trakkides ◽  
Schäfer ◽  
Reichenthaler ◽  
Kühn ◽  
Brandwijk ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Epithelial Mesenchymal Transition ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Factor H ◽  
Retinal Pigment Epithelial Cells ◽  
Cell Contact ◽  
Complement Factor ◽  
Complement Protein ◽  
Mesenchymal Transition

Oxidative stress-induced damage of the retinal pigment epithelium (RPE) and chronic inflammation have been suggested as major contributors to a range of retinal diseases. Here, we examined the effects of oxidative stress on endogenous complement components and proinflammatory and angiogenic responses in RPE cells. ARPE-19 cells exposed for 1–48 h to H2O2 had reduced cell–cell contact and increased markers for epithelial–mesenchymal transition but showed insignificant cell death. Stressed ARPE-19 cells increased the expression of complement receptors CR3 (subunit CD11b) and C5aR1. CD11b was colocalized with cell-derived complement protein C3, which was present in its activated form in ARPE-19 cells. C3, as well as its regulators complement factor H (CFH) and properdin, accumulated in the ARPE-19 cells after oxidative stress independently of external complement sources. This cell-associated complement accumulation was accompanied by increased nlrp3 and foxp3 expression and the subsequently enhanced secretion of proinflammatory and proangiogenic factors. The complement-associated ARPE-19 reaction to oxidative stress, which was independent of exogenous complement sources, was further augmented by the poly(ADP-ribose) polymerase (PARP) inhibitor olaparib. Our results indicate that ARPE-19 cell-derived complement proteins and receptors are involved in ARPE-19 cell homeostasis following oxidative stress and should be considered as targets for treatment development for retinal degeneration.

scholarly journals Polarity and epithelial-mesenchymal transition of retinal pigment epithelial cells in proliferative vitreoretinopathy

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e10136
Author(s):  
Hui Zou ◽  
Chenli Shan ◽  
Linlin Ma ◽  
Jia Liu ◽  
Ning Yang ◽  
...  
Keyword(s):  
Proliferative Vitreoretinopathy ◽  
Molecular Mechanisms ◽  
Epithelial Mesenchymal Transition ◽  
Retinal Pigment ◽  
Notch Pathway ◽  
Retinal Pigment Epithelial Cells ◽  
Cell Contact ◽  
Mesenchymal Transition ◽  
Rpe Cells ◽  
Cell Cell

Under physiological conditions, retinal pigment epithelium (RPE) is a cellular monolayer composed of mitotically quiescent cells. Tight junctions and adherens junctions maintain the polarity of RPE cells, and are required for cellular functions. In proliferative vitreoretinopathy (PVR), upon retinal tear, RPE cells lose cell-cell contact, undergo epithelial-mesenchymal transition (EMT), and ultimately transform into myofibroblasts, leading to the formation of fibrocellular membranes on both surfaces of the detached retina and on the posterior hyaloids, which causes tractional retinal detachment. In PVR, RPE cells are crucial contributors, and multiple signaling pathways, including the SMAD-dependent pathway, Rho pathway, MAPK pathways, Jagged/Notch pathway, and the Wnt/β-catenin pathway are activated. These pathways mediate the EMT of RPE cells, which play a key role in the pathogenesis of PVR. This review summarizes the current body of knowledge on the polarized phenotype of RPE, the role of cell-cell contact, and the molecular mechanisms underlying the RPE EMT in PVR, emphasizing key insights into potential approaches to prevent PVR.

scholarly journals Oxidative stress in retinal pigment epithelial cells increased endogenous complement-dependent inflammatory and angiogenic responses - independent from exogenous complement sources

2019 ◽  
Author(s):  
Timon-Orest Trakkides ◽  
Nicole Schäfer ◽  
Maria Reichenthaler ◽  
Konstanze Kühn ◽  
Volker Enzmann ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Retinal Pigment ◽  
Retinal Pigment Epithelial Cells ◽  
List Type ◽  
Complement Receptors ◽  
Complement Protein ◽  
Functional Link ◽  
Mesenchymal Transition ◽  
Rpe Cells ◽  
Complement Proteins

ABSTRACTOxidative stress-induced damage of the retinal pigment epithelium (RPE) together with chronic inflammation has been suggested as major contributors to retinal diseases. Here, we examine the effects of oxidative stress and endogenous complement components on the RPE and its pro-inflammatory and –angiogenic responses.The RPE cell line, ARPE-19, treated with H2O2 reduced cell-cell contacts, increased marker for epithelial–mesenchymal transition but showed less cell death. Stressed ARPE-19 cells increased the expression of complement receptors CR3 and C5aR1. CR3 was co-localized with cell-derived complement protein C3, which was observed in its activated form in ARPE-19 cells. C3 as well as its regulators CFH and properdin accumulated in ARPE-19 cells after oxidative stress independent from external complement sources. This cell-associated complement accumulation promoted nlrp3 and foxp3 expression and subsequent increased secretion of pro-inflammatory and pro-angiogenic factors. The complement-associated ARPE-19 reaction to oxidative stress, independent from external complement source, was increased by the PARP-inhibitor olaparib.Our results indicated that RPE cell-derived complement proteins and receptors are involved in RPE cell homeostasis following oxidative stress and should be considered as targets for treatment developments for retinal degeneration. GRAPHICAL ABSTRACTWe show a functional link between oxidative stress, complement receptors, endogenous complement proteins, pro-angiogenic and -inflammatory responses in ARPE-19 cells. These effects are independent from extracellularly added complement proteins or receptor ligands. We suggest an oxidative stress-associated autocrine mechanism of complement receptor regulation in ARPE-19 cells in connection with upregulated intracellular proteases.HIGHLIGHTSOxidative stress accumulates complement proteins and receptors in RPE cellsOxidative stress activates the RPE inflammasome without external complement proteinsOxidative stress increases foxp3 expression and IL-8/VEGF secretion in RPE cellsOlaparib enhances pro-inflammatory response of RPE

scholarly journals Epithelial-Mesenchymal Transition and Senescence in the Retinal Pigment Epithelium of NFE2L2/PGC-1α Double Knock-Out Mice

2021 ◽  
Vol 22 (4) ◽  
pp. 1684
Author(s):  
Janusz Blasiak ◽  
Ali Koskela ◽  
Elzbieta Pawlowska ◽  
Mikko Liukkonen ◽  
Johanna Ruuth ◽  
...  
Keyword(s):  
Epithelial Mesenchymal Transition ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Age Related Macular Degeneration ◽  
Cell Contact ◽  
Peroxisome Proliferator ◽  
Filamentous Actin ◽  
Knock Out ◽  
Mesenchymal Transition ◽  
Age Related

Age-related macular degeneration (AMD) is the most prevalent form of irreversible blindness worldwide in the elderly population. In our previous studies, we found that deficiencies in the nuclear factor, erythroid 2 like 2 (NFE2L2) and peroxisome proliferator-activated receptor gamma coactivator 1-α (PGC-1α) genes caused AMD-like pathological phenotypes in mice. In the present work, we show hijacked epithelial-mesenchymal transition (EMT) due to the common loss of PGC-1α and NFE2L2 (double knock-out, dKO) genes in aged animals. The implanted area was assessed by histology, immunohistochemistry and transmission electron microscopy. Confocal microscopy revealed altered regions in the filamentous actin ring. This contrasted with hexagonal RPE morphology in wild-type mice. The ultrastructural RPE features here illustrated loss of apical microvilli, alteration of cell-cell contact, loss of basal in-folding with deposits on Bruch’s membrane, and excessive lipofuscin deposition in dKO samples. We also found the expression of epithelial-mesenchymal transition transcription factors, such as Snail, Slug, collagen 1, vimentin and OB-cadherin, to be significantly different in dKO RPEs. An increased immunoreactivity of senescence markers p16, DEC1 and HMGB1 was also noted. These findings suggest that EMT and senescence pathways may intersect in the retinas of dKO mice. Both processes can be activated by damage to the RPE, which may be caused by increased oxidative stress resulting from the absence of NFE2L2 and PGC-1α genes, important for antioxidant defense. This dKO model may provide useful tools for studying AMD pathogenesis and evaluating novel therapies for this disease.

scholarly journals Nicotinamide suppresses bevacizumab-induced epithelial-mesenchymal transition of ARPE-19 cells by attenuating oxidative stress

2021 ◽  
Vol 14 (4) ◽  
pp. 481-488
Author(s):  
Li Zhou ◽  
◽  
Wen-Juan Chu ◽  
Shan Song ◽  
Xiang-Hui Hao ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Epithelial Mesenchymal Transition ◽  
Treatment Time ◽  
Retinal Pigment ◽  
Optimal Treatment ◽  
Retinal Pigment Epithelial Cells ◽  
Mesenchymal Transition ◽  
Protein Levels ◽  
Total Antioxidant ◽  
Time Point

AIM: To investigate the effects of nicotinamide (NAM) on bevacizumab (BEV)-induced epithelial-mesenchymal transition (EMT) of human retinal pigment epithelial cells (ARPE-19) and the underling mechanisms. METHODS: ARPE-19 cells were treated with BEV for 24, 48, and 72h, and the variation degrees of EMT-related markers (fibronectin, α-SMA, vimentin, and ZO-1) were assessed by Western blotting to select the optimal treatment time point which exhibited the most obvious changes of EMT-related markers for the subsequent experiments. Furthermore, NAM was added to the medium, the mRNA and protein levels of the EMT-related markers were then measured. The accumulation of reactive oxygen species (ROS) and H2O2 and the total antioxidant capacity (TAC) of the cells were also measured to evaluate the level of oxidative stress. RESULTS: After being treated with BEV for 72h, the protein expression levels of EMT-related markers in ARPE-19 cells showed significant changes. Meanwhile the levels of ROS and H2O2 were obviously increased, and the TAC of ARPE-19 cells was decreased. Totally 72h was chosen to be the optimal treatment time point in subsequent experiments. Furthermore, NAM inhibited BEV-induced EMT by downregulating fibronectin, α-SMA, and vimentin and upregulating ZO-1, decreased the accumulation of ROS and H2O2, and enhanced TAC in BEV-treated ARPE-19 cells. CONCLUSION: This study demonstrates that NAM suppressed BEV-induced EMT in ARPE-19 cells by attenuating oxidative stress. Hence, NAM may be a potential therapeutic agent for alleviating neovascular fibrosis of the ocular fundus after anti-vascular endothelial growth factor therapy.

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