scholarly journals Eucalyptol Inhibits Amyloid-β-Induced Barrier Dysfunction in Glucose-Exposed Retinal Pigment Epithelial Cells and Diabetic Eyes

Antioxidants ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 1000
Author(s):  
Dong Yeon Kim ◽  
Min-Kyung Kang ◽  
Eun-Jung Lee ◽  
Yun-Ho Kim ◽  
Hyeongjoo Oh ◽  
...  
Keyword(s):  
Tight Junction ◽  
Retinal Pigment Epithelial ◽  
Retinal Pigment ◽  
Amyloid Β ◽  
Diabetic Mouse ◽  
Retinal Pigment Epithelial Cells ◽  
Barrier Dysfunction ◽  
Blood Retinal Barrier ◽  
Rpe Cells ◽  
Pigment Epithelial

Hyperglycemia elicits tight junction disruption and blood-retinal barrier breakdown, resulting in diabetes-associated vison loss. Eucalyptol is a natural compound found in eucalyptus oil with diverse bioactivities. This study evaluated that eucalyptol ameliorated tight junctions and retinal barrier function in glucose/amyloid-β (Aβ)-exposed human retinal pigment epithelial (RPE) cells and in db/db mouse eyes. RPE cells were cultured in media containing 33 mM glucose or 5 μM Aβ for 4 days in the presence of 1–20 μM eucalyptol. The in vivo animal study employed db/db mice orally administrated with 10 mg/kg eucalyptol. Nontoxic eucalyptol inhibited the Aβ induction in glucose-loaded RPE cells and diabetic mouse eyes. Eucalyptol reversed the induction of tight junction-associated proteins of ZO-1, occludin-1 and matrix metalloproteinases in glucose- or Aβ-exposed RPE cells and in diabetic eyes, accompanying inhibition of RPE detachment from Bruch’s membrane. Adding eucalyptol to glucose- or Aβ-loaded RPE cells, and diabetic mouse eyes reciprocally reversed induction/activation of apoptosis-related bcl-2, bax, cytochrome C/Apaf-1 and caspases. Eucalyptol attenuated the generation of reactive oxygen species and the induction of receptor for advanced glycation end products in Aβ-exposed RPE cells and diabetic eyes. Eucalyptol may ameliorate RPE barrier dysfunction in diabetic eyes through counteracting Aβ-mediated oxidative stress-induced RPE cell apoptosis.

scholarly journals Eucalyptol Blocks Diabetes-Associated Disruption of Tight Junction and Blood Retinal Barrier in Retinal Pigment Epithelial Cells and Diabetic Eyes

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 413-413
Author(s):  
Dongyeon Kim ◽  
Min-kyung Kang ◽  
Young-Hee Kang
Keyword(s):  
Epithelial Cells ◽  
Tight Junction ◽  
Retinal Pigment Epithelial ◽  
Retinal Pigment ◽  
Retinal Pigment Epithelial Cells ◽  
Tight Junction Proteins ◽  
Blood Retinal Barrier ◽  
Pigment Epithelial ◽  
Pigment Epithelial Cells ◽  
Junction Proteins

Abstract Objectives Diabetes-associated retinal impairment has been implicated in diabetic retinopathy. Chronic hyperglycemia leads to disruption of tight junction and breakdown of blood retinal barrier. Eucalyptol is a natural organic essential oil and a monoterpenoid present in eucalyptus oil with anti-inflammatory, anti-diabetic and antioxidant properties. Methods Primary human retinal pigment epithelial cells (HRPEC) were cultured in media containing 33 mM glucose for 4 days in the presence of 1–20 μM eucalyptol. The in vivo animal study employed db/db mice orally administrated with 10 mg/kg eucalyptol. Cell lysates and mouse eye tissue extracts were prepared for Western blotting, in which antibodies of ZO-1, occludin, matrix metalloproteinase (MMP)-2 and MMP-9 were used. Results Eucalyptol enhanced epithelial induction of the tight junction proteins of ZO-1 and occludin reduced by glucose loading. Consistently, oral administration of eucalyptol to db/db mice augmented the eye tissue levels of these tight junction proteins. In addition, the induction of MMP-2 and MMP-9 involved in the degradation of extracellular matrix, was elevated by exposure of glucose to HRPEC, which was encumbered by eucalyptol in a dose-dependent manner. Conclusions These results demonstrated that eucalyptol maintained transepithelial cells integrity and blood retinal barrier in diabetic eyes. Therefore, eucalyptol may be a potent retinoprotective agent combating diabetes-associated retinal malfunction. Funding Sources This work was supported by the National Research Foundation of Korea (NRF) grants funded by the Korea government (2017R1A6A3A04011473).

scholarly journals High glucose promotes the migration of retinal pigment epithelial cells through increased oxidative stress and PEDF expression

2016 ◽  
Vol 311 (3) ◽  
pp. C418-C436 ◽  
Author(s):  
Mitra Farnoodian ◽  
Caroline Halbach ◽  
Cassidy Slinger ◽  
Bikash R. Pattnaik ◽  
Christine M. Sorenson ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
High Glucose ◽  
Retinal Pigment Epithelial ◽  
Retinal Pigment ◽  
Retinal Pigment Epithelial Cells ◽  
Blood Retinal Barrier ◽  
Rpe Cells ◽  
Pigment Epithelial ◽  
Proliferation And Apoptosis ◽  
The Impact

Defects in the outer blood-retinal barrier have significant impact on the pathogenesis of diabetic retinopathy and macular edema. However, the detailed mechanisms involved remain largely unknown. This is, in part, attributed to the lack of suitable animal and cell culture models, including those of mouse origin. We recently reported a method for the culture of retinal pigment epithelial (RPE) cells from wild-type and transgenic mice. The RPE cells are responsible for maintaining the integrity of the outer blood-retinal barrier whose dysfunction during diabetes has a significant impact on vision. Here we determined the impact of high glucose on the function of RPE cells. We showed that high glucose conditions resulted in enhanced migration and increased the level of oxidative stress in RPE cells, but minimally impacted their rate of proliferation and apoptosis. High glucose also minimally affected the cell-matrix and cell-cell interactions of RPE cells. However, the expression of integrins and extracellular matrix proteins including pigment epithelium-derived factor (PEDF) were altered under high glucose conditions. Incubation of RPE cells with the antioxidant N-acetylcysteine under high glucose conditions restored normal migration and PEDF expression. These cells also exhibited increased nuclear localization of the antioxidant transcription factor Nrf2 and ZO-1, reduced levels of β-catenin and phagocytic activity, and minimal effect on production of vascular endothelial growth factor, inflammatory cytokines, and Akt, MAPK, and Src signaling pathways. Thus high glucose conditions promote RPE cell migration through increased oxidative stress and expression of PEDF without a significant effect on the rate of proliferation and apoptosis.

Hesperidin Prevents High Glucose-Induced Damage of Retinal Pigment Epithelial Cells

Planta Medica ◽  
2018 ◽  
Vol 84 (14) ◽  
pp. 1030-1037 ◽  
Author(s):  
Wayne Liu ◽  
Shorong-Shii Liou ◽  
Tang-Yao Hong ◽  
I-Min Liu
Keyword(s):  
High Glucose ◽  
Retinal Pigment Epithelial ◽  
Colorimetric Assay ◽  
Retinal Pigment ◽  
Retinal Pigment Epithelial Cells ◽  
Antioxidant Enzyme Activities ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Rpe Cells ◽  
Pigment Epithelial

AbstractThe present study aimed to determine whether hesperidin, a plant-based active flavanone found in citrus fruits, can prevent high glucose-induced retinal pigment epithelial (RPE) cell impairment. Cultured human RPE cells (ARPE-19) were exposed to a normal glucose concentration (5.5 mM) for 4 d and then soaked in either normal (5.5 mM) or high (33.3 mM) concentrations of D-glucose with or without different concentrations of hesperidin (10, 20, or 40 µM) for another 48 h. The survival rates of the cells were measured using a 3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide reduction assay. With the help of a fluorescent probe, the intracellular production of reactive oxygen species (ROS) was evaluated. Colorimetric assay kits were used to assess the antioxidant enzyme activities, and western blotting was used to measure the expression of apoptosis-related protein. Hesperidin was effective in inhibiting high glucose-induced ROS production, preventing loss of cell viability, and promoting the endogenous antioxidant defense components, including glutathione peroxidase, superoxide dismutase, catalase, and glutathione, in a concentration-dependent manner. Furthermore, high glucose triggered cell apoptosis via the upregulation of caspase-9/3, enhancement of cytochrome c release into the cytosol, and subsequent interruption of the Bax/Bcl-2 balance. These detrimental effects were ameliorated by hesperidin in a concentration-dependent manner. We conclude that through the scavenging of ROS and modulation of the mitochondria-mediated apoptotic pathway, hesperidin may protect RPE cells from high glucose-induced injury and thus may be a candidate in preventing the visual impairment caused by diabetic retinopathy.

Orientation of actin filaments in teleost retinal pigment epithelial cells, and the effect of the lectin, Concanavalin A, on melanosome motility

2014 ◽  
Vol 31 (1) ◽  
pp. 1-10 ◽  
Author(s):  
CHRISTINA KING-SMITH ◽  
RONALD J. VAGNOZZI ◽  
NICOLE E. FISCHER ◽  
PATRICK GANNON ◽  
SATYA GUNNAM
Keyword(s):  
Epithelial Cells ◽  
Actin Filament ◽  
Concanavalin A ◽  
Actin Filaments ◽  
Retinal Pigment Epithelial ◽  
Retinal Pigment ◽  
Retinal Pigment Epithelial Cells ◽  
Rpe Cells ◽  
Pigment Epithelial ◽  
Pigment Epithelial Cells

AbstractRetinal pigment epithelial cells of teleosts contain numerous melanosomes (pigment granules) that exhibit light-dependent motility. In light, melanosomes disperse out of the retinal pigment epithelium (RPE) cell body (CB) into long apical projections that interdigitate with rod photoreceptors, thus shielding the photoreceptors from bleaching. In darkness, melanosomes aggregate through the apical projections back into the CB. Previous research has demonstrated that melanosome motility in the RPE CB requires microtubules, but in the RPE apical projections, actin filaments are necessary and sufficient for motility. We used myosin S1 labeling and platinum replica shadowing of dissociated RPE cells to determine actin filament polarity in apical projections. Actin filament bundles within RPE apical projections are uniformly oriented with barbed ends toward the distal tips. Treatment of RPE cells with the tetravalent lectin, Concanavalin A, which has been shown to suppress cortical actin flow by crosslinking of cell-surface proteins, inhibited melanosome aggregation and stimulated ectopic filopodia formation but did not block melanosome dispersion. The polarity orientation of F-actin in apical projections suggests that a barbed-end directed myosin motor could effect dispersion of melanosomes from the CB into apical projections. Inhibition of aggregation, but not dispersion, by ConA confirms that different actin-dependent mechanisms control these two processes and suggests that melanosome aggregation is sensitive to treatments previously shown to disrupt actin cortical flow.

Carrier-dependent and carrier-independent uptake of myo-inositol in cultured retinal pigment epithelial cells: activation by heat and concentration

1988 ◽  
Vol 66 (9) ◽  
pp. 942-950 ◽  
Author(s):  
Mahin Khatami
Keyword(s):  
Retinal Pigment Epithelial ◽  
Retinal Pigment ◽  
Primary Cultures ◽  
Retinal Pigment Epithelial Cells ◽  
Transport Systems ◽  
Rate Equations ◽  
Rpe Cells ◽  
Major Mechanism ◽  
Pigment Epithelial ◽  
Pigment Epithelial Cells

Transport of myo-inositol (MI) was studied in primary cultures of bovine retinal pigment epithelial (RPE) cells. At low external concentrations (0.01–1 mM), uptake appeared to follow saturation kinetics, although the reciprocal forms of the rate equations did not fit either Lineweaver–Burk or Eadie–Hofstee plots. Increasing external concentrations dramatically changed the pattern of MI entry. At two to three orders of magnitude higher than physiological concentrations, a second saturation occurred (pseudo saturation). Cells incubated with 20 μM [3H]MI for 60 min had a ratio of intracellular to extracellular radioactivity ≥ 8, indicating active transport.MI transport reduction by Na+ replacement or inhibitors (phlorizin, ouabain, amiloride, KSCN, iodoacetamide, MI analogues) was greater when RPE cells were incubated with low (20–400 μM) than with high (10–20 mM) MI concentrations. Cells incubated with 20 μM MI at 53 or 65 °C showed increased transport (up to 560%) compared with cells at 22 °C. The effect on MI uptake (20 μM) of Na+ replacement also was reduced at 53 °C. The uptake of MI involved at least two transport systems. The major mechanism at low external MI concentrations (physiological levels) was a carrier-mediated active process. At high external MI levels, uptake occurred by a diffusion process. A lipotropic effect of MI may be responsible for this increased rate of diffusion.

Isolated bovine retinal pigment epithelial cells express delayed rectifier type and M-type K+ currents

1997 ◽  
Vol 273 (3) ◽  
pp. C790-C803 ◽  
Author(s):  
M. Takahira ◽  
B. A. Hughes
Keyword(s):  
Retinal Pigment Epithelial ◽  
Retinal Pigment ◽  
Retinal Pigment Epithelial Cells ◽  
Delayed Rectifier ◽  
Patch Clamp Technique ◽  
Rpe Cells ◽  
Pigment Epithelial ◽  
Type K ◽  
K Current ◽  
K Currents

Outwardly rectifying K+ currents in freshly isolated bovine retinal pigment epithelial (RPE) cells were characterized using the whole cell and perforated-patch configurations of the patch-clamp technique. All cells exhibited a delayed rectifier type K+ current. This current had an activation threshold voltage of approximately -40 mV, activated with a sigmoidal trajectory, and inactivated completely over a period of several seconds. External tetraethylammonium (TEA) was an effective blocker of the delayed rectifier current [apparent dissociation constant (Kd) = 5.1 mM], but external Ba2+ was relatively ineffective. Approximately 24% of the cells also exhibited a sustained outwardly rectifying K+ current that became activated at voltages positive to approximately -80 mV. This current resembled the neuronal M-current. External Ba2+ was a potent blocker of this current (apparent Kd = 1.1 mM), but external TEA and Cs+ were relatively ineffective. These results indicate that freshly isolated bovine RPE cells express K+ currents of both the delayed rectifier and M types. The latter may contribute to the resting K+ conductances of the apical and basolateral membranes.

scholarly journals Immunochemical analysis of the integrin expression in retinal pigment epithelial cells

2020 ◽  
Author(s):  
Janosch P Heller ◽  
Tristan G Heintz ◽  
Jessica CF Kwok ◽  
Keith R Martin ◽  
James W Fawcett
Keyword(s):  
Retinal Pigment Epithelial ◽  
Expression Profiles ◽  
Retinal Pigment ◽  
Cell Types ◽  
Human Cell Line ◽  
Retinal Pigment Epithelial Cells ◽  
Proper Function ◽  
Integrin Expression ◽  
Rpe Cells ◽  
Pigment Epithelial

AbstractRetinal pigment epithelial (RPE) cells have been used in disease modelling and transplantation studies in retinal diseases. Several types of RPE cells have been trialed, ranging from primary cells and immortalized cell lines to stem cell-derived RPE cells. During aging and in disease, the extracellular environment of the RPE cells changes, interfering with RPE cell adhesion. We hypothesize that this could be a key problem in transplantation studies that have reported lack of adhesion and survival of the transplanted RPE cells. Integrins are essential for the proper function of the RPE, mediating adhesion to Bruch’s membrane, and the binding and subsequent phagocytosis of photoreceptor outer segments. Variability that has been found in clinical trials might be due to the variability of cell types used and their expression profiles of surface molecules. Here, we set out to analyze integrin expression in primary rat RPE cells and in the human cell line ARPE-19 using immunochemistry. We found that both cell types express integrins to varying degrees. After long-term culturing, ARPE-19 cells resemble mature RPE cells, and increase integrin expression. We hence argue that it is important to test the properties of these cells prior to transplantation to avoid failure of adhesion and to facilitate correct function.

scholarly journals Deletion of TSPO Resulted in Change of Metabolomic Profile in Retinal Pigment Epithelial Cells

2019 ◽  
Vol 20 (6) ◽  
pp. 1387 ◽  
Author(s):  
Abdulwahab Alamri ◽  
Lincoln Biswas ◽  
David Watson ◽  
Xinhua Shu
Keyword(s):  
Retinal Pigment Epithelial ◽  
Retinal Pigment ◽  
Nucleotide Metabolism ◽  
Retinal Pigment Epithelial Cells ◽  
Age Related Macular Degeneration ◽  
Clinical Feature ◽  
Rpe Cells ◽  
Pigment Epithelial ◽  
Age Related ◽  
The Impact

Age-related macular degeneration is the main cause of vision loss in the aged population worldwide. Drusen, extracellular lesions formed underneath the retinal pigment epithelial (RPE) cells, are a clinical feature of AMD and associated with AMD progression. RPE cells support photoreceptor function by providing nutrition, phagocytosing outer segments and removing metabolic waste. Dysfunction and death of RPE cells are early features of AMD. The translocator protein, TSPO, plays an important role in RPE cholesterol efflux and loss of TSPO results in increased intracellular lipid accumulation and reactive oxygen species (ROS) production. This study aimed to investigate the impact of TSPO knockout on RPE cellular metabolism by identifying the metabolic differences between wildtype and knockout RPE cells, with or without treatment with oxidized low density lipoprotein (oxLDL). Using liquid chromatography mass spectrometry (LC/MS), we differentiated several metabolic pathways among wildtype and knockout cells. Lipids amongst other intracellular metabolites were the most influenced by loss of TSPO and/or oxLDL treatment. Glucose, amino acid and nucleotide metabolism was also affected. TSPO deletion led to up-regulation of fatty acids and glycerophospholipids, which in turn possibly affected the cell membrane fluidity and stability. Higher levels of glutathione disulphide (GSSG) were found in TSPO knockout RPE cells, suggesting TSPO regulates mitochondrial-mediated oxidative stress. These data provide biochemical insights into TSPO-associated function in RPE cells and may shed light on disease mechanisms in AMD.

scholarly journals Depletion of Mitochondrial DNA in Differentiated Retinal Pigment Epithelial Cells

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Xinqian Hu ◽  
Melissa A. Calton ◽  
Shibo Tang ◽  
Douglas Vollrath
Keyword(s):  
Mitochondrial Dna ◽  
Retinal Pigment Epithelial ◽  
Aerobic Glycolysis ◽  
Retinal Pigment ◽  
Retinal Pigment Epithelial Cells ◽  
Response To Treatment ◽  
Flux Analysis ◽  
Rpe Cells ◽  
Pigment Epithelial ◽  
Mitochondrial Dna Depletion

Abstract We investigated the effects of treating differentiated retinal pigment epithelial (RPE) cells with didanosine (ddI), which is associated with retinopathy in individuals with HIV/AIDS. We hypothesized that such treatment would cause depletion of mitochondrial DNA and provide insight into the consequences of degradation of RPE mitochondrial function in aging and disease. Treatment of differentiated ARPE-19 or human primary RPE cells with 200 µM ddI for 6–24 days was not cytotoxic but caused up to 60% depletion of mitochondrial DNA, and a similar reduction in mitochondrial membrane potential and NDUFA9 protein abundance. Mitochondrial DNA-depleted RPE cells demonstrated enhanced aerobic glycolysis by extracellular flux analysis, increased AMP kinase activation, reduced mTOR activity, and increased resistance to cell death in response to treatment with the oxidant, sodium iodate. We conclude that ddI-mediated mitochondrial DNA depletion promotes a glycolytic shift in differentiated RPE cells and enhances resistance to oxidative damage. Our use of ddI treatment to induce progressive depletion of mitochondrial DNA in differentiated human RPE cells should be widely applicable for other studies aimed at understanding RPE mitochondrial dysfunction in aging and disease.

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