The present study was designed to analyze the metabolites of all-trans-retinal (atRal) and compare the cytotoxicity of atRal versus its derivative all-trans-retinoic acid (atRA) in human retinal pigment epithelial (RPE) cells. We confirmed that atRA was produced in normal pig neural retina and RPE. The amount of all-trans-retinol (atROL) converted from atRal was about 2.7 times that of atRal-derived atRA after incubating RPE cells with 10 μmol/L atRal for 24 h, whereas atRA in medium supernatant is more plentiful (91 vs. 29 pmol/mL), suggesting that atRA conversion facilitates elimination of excess atRal in the retina. Moreover, we found that mRNA expression of retinoic acid-specific hydroxylase CYP26b1 was dose-dependently up-regulated by atRal exposure in RPE cells, indicating that atRA inactivation may be also initiated in atRal-accumulated RPE cells. Our data show that atRA-caused viability inhibition was evidently reduced compared with the equal concentration of its precursor atRal. Excess accumulation of atRal provoked intracellular reactive oxygen species (ROS) overproduction, heme oxygenase-1 (HO-1) expression, and increased cleaved poly(ADP-ribose) polymerase 1 (PARP1) expression in RPE cells. In contrast, comparable dosage of atRA-induced oxidative stress was much weaker, and it could not activate apoptosis in RPE cells. These results suggest that atRA generation is an antidotal metabolism pathway for atRal in the retina. Moreover, we found that in the eyes of ABCA4^-/-RDH8^-/- mice, a mouse model with atRal accumulation in the retina, the atRA content was almost the same as that in the wild type. It is possible that atRal accumulation simultaneously and equally promotes atRA synthesis and clearance in eyes of ABCA4^-/-RDH8^-/- mice, thus inhibiting the further increase of atRA in the retina. Our present study provides further insights into atRal clearance in the retina.
ATP-Binding Cassette Transporters/physiology* ; Alcohol Oxidoreductases/physiology* ; Animals ; Cell Survival/drug effects* ; Cells, Cultured ; Humans ; Inactivation, Metabolic ; Mice ; Retina/metabolism* ; Retinal Pigment Epithelium/metabolism* ; Swine ; Tretinoin/pharmacology*

OBJECTIVETo observe the contribution of Borneolum syntheticum to the intervention effect of Liuwei Dihuang Pill (, LDP) on experimental retinal degeneration, and initially investigate the mechanism of Borneolum syntheticum as meridian-lead-in drug.

METHODSA total of 180 sodium iodateinduced retinital degeneration rats were randomly divided into three groups, including distilled water group, LDP group, and LDP+Borneolum syntheticum (LDP+BS) group. Twenty normal rats were fed regularly without any treatment as normal control. On day 7 and 14 after treatment, histopathological study and transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) test were performed to evaluate the retinopathy. Claudin-5 expression at blood-retina barrier (BRB) was detected by Western blot at different time points from 0.5 to 8 h after gavage.

RESULTSOn day 7 and 14 after treatment, the retinal lesion grades were significantly different among the three groups (P<0.05). The grade in the LDP+BS group was significantly less than the LDP and distilled water groups (both P<0.05), no significant difference was observed between the LDP and distilled water groups (P>0.05). The apoptosis rates in the LDP+BS group was significantly less than the distilled water and LDP groups (both P<0.05), while there was no significant difference between LDP and distilled water groups (P>0.05). Expression of claudin-5 in LDP+BS group was significantly less than the other two groups at 0.5, 1 and 2 h after gavage (P<0.05). There was no apparent difference among the three groups at 4 and 8 h after gavage (P>0.05).

CONCLUSIONBorneolum syntheticum could strengthen the effect of LDP on experimental retinal degeneration, indicated that Borneolum syntheticum might play the role of meridian-lead-in drug in the formula. The mechanism may be due to Borneolum syntheticum could promote the physiologically openness of bloodretina barrier through transiently affecting the expression of claudin-5.

Animals ; Apoptosis ; drug effects ; Claudin-5 ; metabolism ; Disease Models, Animal ; Drugs, Chinese Herbal ; pharmacology ; therapeutic use ; Rats, Sprague-Dawley ; Retinal Degeneration ; chemically induced ; drug therapy ; pathology ; Retinal Pigment Epithelium ; drug effects ; pathology ; Time Factors

OBJECTIVEOxidative stress plays an important role in retinal pigmental epithelium (RPE) death during aging and the development of age-related macular degeneration. Although early reports indicate that reactive oxygen species (ROS) including H₂O₂ can trigger apoptosis at lower concentrations and necrosis at higher concentrations, the exact molecular mechanism of RPE death is still unclear. The purpose of this study was to investigate the molecular pathways involved in RPE death induced by exogenous ROS, especially at higher concentrations.

METHODSCultured ARPE-19 cells were treated with H₂O₂ at different concentrations and cell viability was measured with the MTT assay. Cell death was morphologically studied by microscopy using APOPercentage assay and PI staining. Furthermore, the impact of oxidative stress on ARPE-19 cells was assessed by HO-1 and PARP-1 Western blotting and by the protection of antioxidant EGCG. Calcium influx was determined using the fura-2 calcium indicator and the role of intracellular calcium overload in ARPE-19 cell death was evaluated following cobalt treatment to block calcium effects.

RESULTSH₂O₂ reduced the viability of ARPE-19 cells in a concentration-dependent manner, which was presented as a typical s-shaped curve. Cell death caused by high concentrations of H₂O₂ was confirmed to be programmed necrosis. Morphologically, dying ARPE-19 cells were extremely swollen and lost the integrity of their plasma membrane, positively detected with APOPercentage assay and PI staining. 24-hour treatment with 500 μmol/L H₂O₂ induced remarkable up-regulation of HO-1 and PARP-1 in ARPE-19 cells. Moreover, antioxidant treatment using EGCG effectively protected cells from H₂O₂-induced injury, increasing cell viability from 14.17%±2.31% to 85.77%±4.58%. After H₂O₂ treatment, intracellular calcium levels were highly elevated with a maximum concentration of 1200 nM. Significantly, the calcium channel inhibitor cobalt was able to blunt this calcium influx and blocked the necrotic pathway, rescuing the ARPE-19 cell from H₂O₂-induced death.

CONCLUSIONSAt high concentrations, H₂O₂ induces ARPE-19 cell death through a regulated necrotic pathway with calcium overload as a critical step in the cell death program.

Antioxidants ; pharmacology ; Apoptosis ; drug effects ; Blotting, Western ; Calcium ; metabolism ; Calcium Channel Blockers ; pharmacology ; Cell Culture Techniques ; Cell Line ; Cell Survival ; drug effects ; Dose-Response Relationship, Drug ; Heme Oxygenase-1 ; metabolism ; Humans ; Hydrogen Peroxide ; toxicity ; Necrosis ; drug therapy ; Oxidative Stress ; drug effects ; Poly (ADP-Ribose) Polymerase-1 ; Poly(ADP-ribose) Polymerases ; metabolism ; Retinal Pigment Epithelium ; drug effects ; enzymology ; metabolism ; pathology

The aim of this study is to prepare hyaluronic acid (HA) modified core-shell liponanoparticles (pHA-LCS-NPs) as gene delivery system and investigate its gene transfection efficiency in human retinal pigment epithelium (ARPE-19) cells in vitro. The pHA-LCS-NPs was prepared by firstly hydrating dry lipid film with CS-NPs suspension to get LCS-NPs, then modifying the lipid bilayer with HA by amidation reaction between HA and dioleoyl phosphatidylethanolamine (DOPE). Its morphology, particle size and zeta potential were investigated. XTT assay was used to evaluate the cell safety of different vectors in vitro. The gene transfection efficiency of pHA-LCS-NPs modified with different contents of HA was investigated in ARPE-19 cells with green fluorescent protein (pEGFP) as the reporter gene. The results showed that the obtained pHA-LCS-NPs exhibited a clear core-shell structure with the average particles size of (214.9 +/- 7.2) nm and zeta potential of (-35 +/- 3.7) mV. The 24 h cumulative release of gene from pHA-LCS-NPs was less than 30%. After 48 h incubation, gene transfection efficiency of pHA-LCS-NPs/pEGFP was 1.81 times and 3.75 times higher than that of CS-NPs/pEGFP and naked pEGFP, respectively. Also no obvious cytotoxicity was observed on pHA-LCS-NPs. It suggested that the pHA-LCS-NPs might be promising non-viral gene delivery systems with high efficiency and low cytotoxicity.
Cell Survival ; Gene Transfer Techniques ; Genes, Reporter ; Genetic Vectors ; Green Fluorescent Proteins ; metabolism ; Humans ; Hyaluronic Acid ; chemistry ; pharmacology ; Lipids ; Nanoparticles ; Particle Size ; Phosphatidylethanolamines ; chemistry ; pharmacology ; Retinal Pigment Epithelium ; drug effects ; Transfection

OBJECTIVE: This paper applied a transcriptomic approach to investigate the mechanisms of adriamycin (ADR) in treating proliferative vitreoretinopathy (PVR) using ARPE-19 cells. METHODS: The growth inhibitory effects of ADR on ARPE-19 cells were assessed by sulforhodamine B (SRB) assay and propidium iodide (PI) staining using flow cytometry. The differentially expressed genes between ADR-treated ARPE-19 cells and normal ARPE-19 cells and the signaling pathways involved were investigated by microarray analysis. Mitochondrial function was detected by JC-1 staining using flow cytometry and the Bcl-2/Bax protein family. The phosphorylated histone H2AX (γ-H2AX), phosphorylated checkpoint kinase 1 (p-CHK1), and phosphorylated checkpoint kinase 2 (p-CHK2) were assessed to detect DNA damage and repair. RESULTS: ADR could significantly inhibit ARPE-19 cell proliferation and induce caspase-dependent apoptosis in vitro. In total, 4479 differentially expressed genes were found, and gene ontology items and the p53 signaling pathway were enriched. A protein-protein interaction analysis indicated that the TP53 protein molecules regulated by ADR were related to DNA damage and oxidative stress. ADR reduced mitochondrial membrane potential and the Bcl-2/Bax ratio. p53-knockdown restored the activation of c-caspase-3 activity induced by ADR by regulating Bax expression, and it inhibited ADR-induced ARPE-19 cell apoptosis. Finally, the levels of the γ-H2AX, p-CHK1, and p-CHK2 proteins were up-regulated after ADR exposure. CONCLUSIONS The mechanism of ARPE-19 cell death induced by ADR may be caspase-dependent apoptosis, and it may be regulated by the p53-dependent mitochondrial dysfunction, activating the p53 signaling pathway through DNA damage.
Apoptosis ; Caspases/metabolism* ; Cell Proliferation ; Cell Survival/drug effects* ; Doxorubicin/pharmacology* ; Flow Cytometry ; Gene Expression Profiling ; Gene Expression Regulation ; Humans ; Membrane Potential, Mitochondrial ; Oligonucleotide Array Sequence Analysis ; Oxidative Stress/drug effects* ; Phosphorylation ; Propidium/chemistry* ; RNA, Small Interfering/metabolism* ; Retinal Pigment Epithelium/metabolism* ; Rhodamines/chemistry* ; Signal Transduction/drug effects* ; Transcriptome ; Tumor Suppressor Protein p53/metabolism* ; Vitreoretinopathy, Proliferative/drug therapy*

PURPOSE: To evaluate the effects of bevacizumab on expression of B-cell leukemia/lymphoma (Bcl)-2 and apoptosis in retinal pigment epithelial (RPE) cells under oxidative stress conditions. METHODS: RPE cells were treated with H2O2 (0, 100, 200, 300, and 400 microM) and bevacizumab at or above the doses normally used in clinical practice (0, 0.33, 0.67, 1.33, and 2.67 mg/mL). Cell apoptosis was measured using flow cytometry with annexin V-fluorescein isothiocyanate. The expression of Bcl-2 mRNA was determined using reverse transcription polymerase chain reaction. RESULTS: Under low oxidative stress conditions (H2O2 100 microM), cell apoptosis was not significantly different at any concentration of bevacizumab, but Bcl-2 mRNA expression decreased with increasing concentration of bevacizumab (0.33, 0.67, 1.33, and 2.67 mg/mL). Under moderate oxidative stress conditions (H2O2 200 microM), Bcl-2 mRNA expression decreased with increasing concentration of bevacizumab (0.33, 0.67, 1.33, and 2.67 mg/mL), but cell apoptosis increased only at 2.67 mg/mL of bevacizumab. Under high oxidative stress (300 microM) conditions, cell apoptosis increased at high concentrations of bevacizumab (1.33 and 2.67 mg/mL), but it did not correlate with Bcl-2 expression. CONCLUSIONS: Withdrawal of vascular endothelial growth factor can lead to RPE cell apoptosis and influences the expression of anti-apoptotic genes such as Bcl-2 under oxidative stress conditions. Since oxidative stress levels of each patient are unknown, repeated injections of intravitreal bevacizumab, as in eyes with age-related macular degeneration, might influence RPE cell survival.
Angiogenesis Inhibitors/*pharmacology ; Apoptosis/*drug effects ; Bevacizumab/*pharmacology ; Cell Line ; Enzyme-Linked Immunosorbent Assay ; Flow Cytometry ; Gene Expression Regulation/physiology ; Humans ; Hydrogen Peroxide/toxicity ; Oxidative Stress/drug effects ; Proto-Oncogene Proteins c-bcl-2/*genetics ; RNA, Messenger/genetics ; Real-Time Polymerase Chain Reaction ; Retinal Pigment Epithelium/*drug effects/metabolism/pathology ; Vascular Endothelial Growth Factor A/antagonists & inhibitors

The purpose of this study was to investigate the protective effect of puerarin on retina pigment epithelial (RPE) cells of diabetic rats against apoptosis. One hundred and eight Sprague-Dawley (SD) rats were randomly divided into 3 groups: control group, streptozotocin (STZ) group and puerarin group. STZ and puerarin groups received 3 d of STZ injection (45 mg/kg per day, i.p.). Additionally, puerarin groups were treated with puerarin (140 mg/kg, i.p.) from the 4th day to the end of experiment. The rats from different groups were sacrificed on 20, 40 and 60 d after STZ injection for harvesting RPE cells. Western blot analysis, DNA laddering, RT-PCR and immunohistochemistry were used for determining the expression of nitrotyrosine (NT, the foot print of peroxynitrite), cell apoptosis, iNOS mRNA and Fas/Fas ligand (FasL) signal transduction in RPE cells, respectively. The results showed that control group maintained low apoptosis level and little NT, iNOS mRNA, Fas/FasL protein expressions, as well as normal blood glucose and body weight during 60 d of the experiment. Compared with control group, STZ group showed obvious apoptosis and higher NT, iNOS mRNA, Fas/FasL protein expressions from 20 d after STZ injection. Puerarin relieved apoptosis of RPE cells and decreased NT, iNOS mRNA, Fas/FasL protein expressions in puerarin group 20 or 40 d after STZ injection, compared with STZ group. These results suggest puerarin can decrease RPE cells apoptosis in diabetic rats by reducing peroxynitrite level and iNOS expression, thus being a potential therapeutic agent in controlling of diabetic retinopathy.
Animals ; Apoptosis ; drug effects ; Diabetes Mellitus, Experimental ; metabolism ; pathology ; Diabetic Retinopathy ; prevention & control ; Fas Ligand Protein ; metabolism ; Isoflavones ; pharmacology ; Male ; Nitric Oxide Synthase Type II ; genetics ; metabolism ; Peroxynitrous Acid ; metabolism ; Protective Agents ; pharmacology ; RNA, Messenger ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley ; Retinal Pigment Epithelium ; pathology ; fas Receptor ; metabolism

PURPOSE: To investigate the effects of resveratrol on the expression of hypoxia-inducible factor 1alpha (HIF-1alpha) and vascular endothelial growth factor (VEGF) in human adult retinal pigment epithelial (ARPE-19) cells, and on experimental choroidal neovascularization (CNV) in mice. MATERIALS AND METHODS: ARPE-19 cells were treated with different concentrations of resveratrol and then incubated under hypoxic conditions with subsequent evaluation of cell viability, expression of HIF-1alpha, and expression of VEGF. The effects of resveratrol on the synthesis and degradation of hypoxia-induced HIF-1alpha were evaluated using inhibitors of the PI3K/Akt/mTOR and the ubiquitin proteasome pathways. In animal studies, CNV lesions were induced in C57BL/6 mice by laser photocoagulation. After 7 days of oral administration of resveratrol or vehicle, which began one day after CNV induction, image analysis was used to measure CNV areas on choroidal flat mounts stained with isolectin IB4. RESULTS: In ARPE-19 cells, resveratrol significantly inhibited HIF-1alpha and VEGF in a dose-dependent manner, by blocking the PI3K/Akt/mTOR signaling pathway and by promoting proteasomal HIF-1alpha degradation. In mice experiments, orally administered resveratrol significantly inhibited CNV growth in a dose-dependent manner. CONCLUSION: Resveratrol may have therapeutic value in the management of diseases involving pathological neovascularization.
Adult ; Animals ; Anoxia/metabolism/physiopathology ; Cell Survival/drug effects ; Choroidal Neovascularization/*metabolism/pathology ; Humans ; Hypoxia-Inducible Factor 1, alpha Subunit/*drug effects/metabolism ; Mice ; Mice, Inbred C57BL ; Phosphatidylinositol 3-Kinases/antagonists & inhibitors/*physiology ; Proteasome Endopeptidase Complex ; Proto-Oncogene Proteins c-akt/antagonists & inhibitors/*physiology ; Retinal Pigment Epithelium/*drug effects/metabolism ; Signal Transduction ; Stilbenes/administration & dosage/*pharmacology ; TOR Serine-Threonine Kinases/antagonists & inhibitors/*physiology ; Ubiquitin ; Vascular Endothelial Growth Factor A/*drug effects/metabolism

PURPOSE: To study the effect of systemic administration of phenyl-N-tert-butylnitrone (PBN) on the degeneration of photoreceptor cells in rd mice. METHODS: PBN was injected intraperitoneally into FVB/rd mice on postnatal days (P) 5 to 14 (group A), and P10 to 18 (group B). At days P14, 16, 18, 20 and 27, morphological changes and apoptosis were analyzed by staining with hematoxylin and eosin or DAPI. The effect of PBN on apoptosis was analyzed in retinal pigment epithelial (RPE) cells by the measurement of caspase-3 activity. RESULTS: In control and group B mice, the outer nuclear layer (ONL) of the retina was composed of 8-10 rows at P12, and rapidly decreased to one row at P18. In group A mice, the ONL was preserved with 5-7 rows at P18, and decreased to one row at P22. PBN inhibited caspase-3 activity in cultured RPE cells. CONCLUSIONS: PBN delayed, but did not block, the degeneration of photoreceptor cells in rd mice. PBN may exert its inhibitory effect during the early phase of photoreceptor cell degeneration.
Retinal Degeneration/*drug therapy/metabolism/pathology ; Pigment Epithelium of Eye/drug effects/metabolism/pathology ; Photoreceptors, Vertebrate/drug effects/metabolism/*pathology ; Nitrogen Oxides/*administration & dosage/pharmacokinetics/therapeutic use ; Neuroprotective Agents/*administration & dosage/pharmacokinetics/therapeutic use ; Mice ; Male ; Injections, Intraperitoneal ; Free Radical Scavengers/*administration & dosage/pharmacokinetics/therapeutic use ; Follow-Up Studies ; Female ; Enzyme Precursors/metabolism ; Disease Models, Animal ; Cells, Cultured ; Caspases/metabolism ; Caspase 3 ; Apoptosis/drug effects ; Animals

PURPOSE: To investigate the production of long pentraxin 3 (PTX3) in response to tunicamycin-induced endoplasmic reticulum (ER) stress and its role in ER stress-associated cell death, PTX3 expression was evaluated in the human retinal pigment epithelial cell line, ARPE-19. METHODS: PTX3 production in ARPE-19 cells was analyzed in the absence or presence of tunicamycin treatment by enzyme-linked immunosorbent assay. PTX3 protein and mRNA levels were estimated using western blot analysis and real-time reverse transcription-polymerase chain reaction, respectively. Protein and mRNA levels of CCAAT-enhancer-binding protein homologous protein (CHOP) and ARPE-19 cell viability were measured in the presence of tunicamycin-induced ER stress in control or PTX3 small hairpin RNA (shRNA)-transfected ARPE-19 cells. RESULTS: The protein and mRNA levels of PTX3 were found to be significantly increased by tunicamycin treatment. PTX3 production was significantly decreased in inositol-requiring enzyme 1α shRNA-transfected ARPE-19 cells compared to control shRNA-transfected cells. Furthermore, pretreatment with the NF-κB inhibitor abolished tunicamycin-induced PTX3 production. Decreased cell viability and prolonged protein and mRNA expression of CHOP were observed under tunicamycin-induced ER stress in PTX3 shRNA transfected ARPE-19 cells. CONCLUSIONS: These results suggest that PTX3 production increased in the presence of tunicamycin-induced ER stress. Therefore, PTX3 could be an important protector of ER stress-induced cell death in human retinal pigment epithelial cells. Inositol-requiring enzyme 1α and the NF-κB signaling pathway may serve as potential targets for regulation of PTX3 expression in the retina. Therefore, their role in PTX3 expression needs to be further investigated.
Anti-Bacterial Agents/pharmacology ; Apoptosis ; Blotting, Western ; C-Reactive Protein/biosynthesis/*genetics ; Cells, Cultured ; Endoplasmic Reticulum Stress/*drug effects/genetics ; Enzyme-Linked Immunosorbent Assay ; *Gene Expression Regulation ; Humans ; Polymerase Chain Reaction ; RNA, Messenger/*genetics ; Retinal Pigment Epithelium/*metabolism/pathology ; Serum Amyloid P-Component/biosynthesis/*genetics ; Tunicamycin/*pharmacology