Human Retinal Pigment Epithelial ARPE-19 Research Articles

Anthocyanins Inhibits Oxidative Injury in Human Retinal Pigment Epithelial ARPE-19 Cells via Activating Heme Oxygenase-1.

Anthocyanins belong to phenolic pigments and are known to have various pharmacological activities. This study aimed to investigate whether anthocyanins could inhibit hydrogen peroxide (H2O2)-induced oxidative damage in human retinal pigment epithelial ARPE-19 cells. Our results indicated that anthocyanins suppressed H2O2-induced genotoxicity, while inhibiting reactive oxygen species (ROS) production and preserving diminished glutathione. Anthocyanins also suppressed H2O2-induced apoptosis by reversing the Bcl-2/Bax ratio and inhibiting caspase-3 activation. Additionally, anthocyanins attenuated the release of cytochrome c into the cytosol, which was achieved by interfering with mitochondrial membrane disruption. Moreover, anthocyanins increased the expression of heme oxygenase-1 (HO-1) as well as its activity, which was correlated with the phosphorylation and nuclear translocation of nuclear factor-erythroid-2 related factor 2 (Nrf2). However, the cytoprotective and anti-apoptotic effects of anthocyanins were significantly attenuated by the HO-1 inhibitor, demonstrating that anthocyanins promoted Nrf2-induced HO-1 activity to prevent ARPE-19 cells from oxidative stress. Therefore, our findings suggest that anthocyanins, as Nrf2 activators, have potent ROS scavenging activity and may have the potential to protect ocular injury caused by oxidative stress.

Urban aerosol particulate matter promotes mitochondrial oxidative stress-induced cellular senescence in human retinal pigment epithelial ARPE-19 cells

Environmental exposure to urban particulate matter (UPM) is a serious health concern worldwide. Although several studies have linked UPM to ocular diseases, no study has reported effects of UPM exposure on senescence in retinal cells. Therefore, this study aimed to investigate the effects of UPM on senescence and regulatory signaling in human retinal pigment epithelial ARPE-19 cells. Our study demonstrated that UPM significantly promoted senescence, with increased senescence-associated β-galactosidase activity. Moreover, both mRNA and protein levels of senescence markers (p16 and p21) and the senescence-associated secretory phenotype, including IL-1β, matrix metalloproteinase-1, and −3 were upregulated. Notably, UPM increased mitochondrial reactive oxygen species-dependent nuclear factor-kappa B (NF-κB) activation during senescence. In contrast, use of NF-κB inhibitor Bay 11–7082 reduced the level of senescence markers. Taken together, our results provide the first in vitro preliminary evidence that UPM induces senescence by promoting mitochondrial oxidative stress-mediated NF-κB activation in ARPE-19 cells.

Isolation and Identification of Dihydrophenanthrene Derivatives from Dendrobium virgineum with Protective Effects against Hydrogen-Peroxide-Induced Oxidative Stress of Human Retinal Pigment Epithelium ARPE-19 Cells

Oxidative stress is a significant factor in the development of age-related macular degeneration (AMD), which results from cell damage, dysfunction, and death in the retinal pigmented epithelium (RPE). The use of natural compounds with antioxidant properties to protect RPE cells from oxidative stress has been explored in Dendrobium, a genus of orchid plants belonging to the family Orchidaceae. Two new compounds and seven known compounds from the MeOH extract of the whole plant of Dendrobium virgineum were successfully isolated and structurally characterized. Out of all the compounds isolated, 2-methoxy-9,10-dihydrophenanthrene-4,5-diol (3) showed the highest protective effect against hydrogen peroxide (H2O2)-induced oxidative stress in human retinal pigment epithelial (ARPE-19) cells. Therefore, it was selected to evaluate its protective effect and mechanism on oxidative-stress-induced ARPE-19 cells. Cells were pre-treated with compound 3 at 25, 50, and 100 µg/mL for 24 h and then induced with 400 µM H2O2 for 1 h. The results demonstrated that compound 3 significantly (p < 0.05) increased cell viability by 10-35%, decreased ROS production by 10-30%, and reduced phosphorylation of p38, ERK1/2, and SAPK/JNK by 20-70% in a dose-dependent manner without toxicity. Furthermore, compound 3 significantly (p < 0.05) modulated the expression of apoptosis pathway proteins (cytochrome c, Bax and Bcl-2) by 20-80%, and enhanced SOD, CAT, and GPX activities, and GSH levels in a dose-dependent manner. These results suggest that compound 3 protects ARPE-19 cells against oxidative stress through MAPKs and apoptosis pathways, including the antioxidant system. Thus, compound 3 could be considered as an antioxidant agent for preventing AMD development by protecting RPE cells from oxidative stress and maintaining the retina. These findings open up new possibilities for the use of natural compounds in the treatment of AMD and other oxidative-stress-related conditions.

Phloroglucinol Attenuates DNA Damage and Apoptosis Induced by Oxidative Stress in Human Retinal Pigment Epithelium ARPE-19 Cells by Blocking the Production of Mitochondrial ROS.

Phloroglucinol, a phenolic compound, is known to possess a potent antioxidant ability. However, its role in retinal cells susceptible to oxidative stress has not been well elucidated yet. Thus, the objective of this study was to evaluate whether phloroglucinol could protect against oxidative damage in cultured human retinal pigment epithelium ARPE-19 cells. For this purpose, ARPE-19 cells were stimula ted with hydrogen peroxide (H2O2) to mimic oxidative stress. Cell viability, cytotoxicity, apoptosis, reactive oxygen species (ROS) generation, mitochondrial function, DNA damage, and autophagy were then assessed. Our results revealed that phloroglucinol ameliorated cell viability, cytotoxicity, and DNA damage in H2O2-exposued ARPE-19 cells and blocked production of ROS. Phloroglucinol also counteracted H2O2-induced apoptosis by reducing Bax/Bcl-2 ratio, blocking activation of caspase-3, and inhibiting degradation of poly (ADP-ribose) polymerase. H2O2 caused mitochondrial impairment and increased expression levels of mitophagy markers such as PINK1and PARKIN known to be associated with mitochondrial ROS (mtROS) generation and cytosolic release of cytochrome c. However, these changes were significantly attenuated by phloroglucinol. Mito-TEMPO, a selective mitochondrial antioxidant, further enhanced the protective effect of phloroglucinol against dysfunctional mitochondria. Furthermore, H2O2 induced autophagy, but not when ARPE-19 cells were pretreated with phloroglucinol, meaning that autophagy by H2O2 contributed to the pro-survival mechanism and that phloroglucinol protected ARPE-19 cells from apoptosis by blocking autophagy. Taken together, these results suggest that phloroglucinol can inhibit oxidative stress-induced ARPE-19 cell damage and dysfunction by protecting DNA damage, autophagy, and subsequent apoptosis through mitigation of mtROS generation. Thus, phloroglucinol might have therapeutic potential to prevent oxidative stress-mediated damage in RPE cells.

LncRNA FLG-AS1 Mitigates Diabetic Retinopathy by Regulating Retinal Epithelial Cell Inflammation, Oxidative Stress, and Apoptosis via miR-380-3p/SOCS6 Axis.

The objective of this study is to investigate lncRNA FLG-AS1-mediated miR-380-3p/SOCS6 axis in inflammation, oxidative stress, and apoptosis of retinal epithelial cells in diabetic retinopathy (DR). Fasting blood was collected from 60 DR patients and 60 healthy controls. The Pearson correlation was used to analyze the correlation between the expression levels of FLG-AS1 and miR-380-3p in DR patients. qRT-PCR and/or Western blotting were used to detect the expression of FLG-AS1, miR-380-3p, and SOCS6. After gain of function of FLG-AS1 or SOCS6 or loss of function of miR-380-3p, high glucose (HG)-treated human retinal pigment epithelial ARPE-19 cells were subjected to TUNEL assessment of apoptosis. ELISA was performed to detect the expression levels of IL-1β, IL-6, and TNF-α in cell culturesupernatant. DCFH-DA was used to detect the level of ROS in the cells. MDA and SOD assay kits were used to measure the activity of MDA and SOD in the cells. Dual-luciferase reporter assay was performed to verify the binding between miR-380-3p and FLG-AS1 or between miR-380-3p and SOCS6. Streptozotocin injections were used to induce diabetes in rats which were injected with FLG-AS1 overexpression lentiviral vectors in the eye. Twenty weeks later, retinal tissue was isolated and stained with hematoxylin-eosin or TUNEL. Compared to that in healthy controls, FLG-AS1 expression decreased 2.5-fold and miR-380-3p expression increased 2.6-fold in the serum of DR patients. The expression levels of FLG-AS1 and miR-380-3p were negatively correlated in DR patients (r = -0.3772, P = 0.003). Overexpression of FLG-AS1 reduced inflammation, oxidative stress, and apoptosis of HG-treated ARPE-19 cells and alleviated retinal injury in diabetic rats. FLG-AS1 promoted the expression of SOCS6 by targeting miR-380-3p. Inhibition of miR-380-3p or overexpression of SOCS6 reduced inflammation, oxidative stress, and apoptosis of HG-treated ARPE-19 cells. FLG-AS1 mitigates DR by regulating retinal epithelial cell inflammation, oxidative stress, and apoptosis via the miR-380-3p/SOCS6 axis.

MicroRNA-5195-3p alleviates high glucose‑induced injury in human ARPE-19 cells by targeting GMFB.

Hyperglycemia is generally considered to be an important cause of diabetic retinopathy (DR). The aim of the present study was to investigate the role of miR-5195-3p in high glucose (HG)-induced human retinal pigment epithelial ARPE-19 cell injury. Here, we first found that the expression level of miR-5195-3p was significantly downregulated in HG-stimulated ARPE-19 cells using reverse transcription quantitative PCR. Overexpression of miR-5195-3p attenuated the impaired cell viability, increased apoptosis and pro-inflammatory cytokines secretion in ARPE-19 cells under HG condition using CCK-8 assay, flow cytometry and ELISA assay, respectively. Luciferase reporter assay showed that miR-5195-3p could specifically bind to the 3’UTR of glia maturation factor-β (GMFB). GMFB overexpression reversed, while knockdown enhanced the protective effects of miR-5195-3p overexpression against HG-induced ARPE-19 cell injury. In summary, miR-5195-3p targeting GMFB might be a potential therapeutic target for DR.

Effect of space flight on the behavior of human retinal pigment epithelial ARPE-19 cells and evaluation of coenzyme Q10 treatment.

Astronauts on board the International Space Station (ISS) are exposed to the damaging effects of microgravity and cosmic radiation. One of the most critical and sensitive districts of an organism is the eye, particularly the retina, and > 50% of astronauts develop a complex of alterations designated as spaceflight-associated neuro-ocular syndrome. However, the pathogenesis of this condition is not clearly understood. In the current study, we aimed to explore the cellular and molecular effects induced in the human retinal pigment ARPE-19 cell line by their transfer to and 3-day stay on board the ISS in the context of an experiment funded by the Agenzia Spaziale Italiana. Treatment of cells on board the ISS with the well-known bioenergetic, antioxidant, and antiapoptotic coenzyme Q10 was also evaluated. In the ground control experiment, the cells were exposed to the same conditions as on the ISS, with the exception of microgravity and radiation. The transfer of ARPE-19 retinal cells to the ISS and their living on board for 3days did not affect cell viability or apoptosis but induced cytoskeleton remodeling consisting of vimentin redistribution from the cellular boundaries to the perinuclear area, underlining the collapse of the network of intermediate vimentin filaments under unloading conditions. The morphological changes endured by ARPE-19 cells grown on board the ISS were associated with changes in the transcriptomic profile related to the cellular response to the space environment and were consistent with cell dysfunction adaptations. In addition, the results obtained from ARPE-19 cells treated with coenzyme Q10 indicated its potential to increase cell resistance to damage.

MicroRNA-100 Mediates Hydrogen Peroxide-Induced Apoptosis of Human Retinal Pigment Epithelium ARPE-19 Cells.

This study investigated the regulatory role of microRNA 100 (miR-100) in hydrogen peroxide (H2O2)-induced apoptosis of human retinal pigment epithelial ARPE-19 cells. H2O2 induced oxidative cell death of cultured ARPE-19 cells was measured by cytotoxicity assay. qRT-PCR was used to quantify cytosolic and extracellular contents of miR-100. Kinase and miR-100 inhibition treatments were applied to determine the regulatory signaling pathways involved in cell death regulation. H2O2 dose-dependently reduced viability of ARPE-19 cells and simultaneously upregulated miR-100 levels in both cytosolic and extracellular compartments. Western blotting detection indicated that H2O2 elicited hyperphosphorylation of PI3K/Akt, ERK1/2, JNK, p38 MAPK, and p65 NF-κB. Further kinase inhibition experiments demonstrated that PI3K, p38 MAPK, and NF-κB activities were involved in oxidative-stress-induced miR-100 upregulation in ARPE-19 cells, while blockade of PI3K, JNK, and NF-κB signaling significantly attenuated the oxidative cell death. Intriguingly, MiR-100 antagomir treatment exerted a cytoprotective effect against the H2O2-induced oxidative cell death through attenuating the oxidation-induced AMPK hyperphosphorylation, restoring cellular mTOR and p62/SQSTM1 levels and upregulating heme oxygenase-1 expression. These findings support that miR-100 at least in part mediates H2O2-induced cell death of ARPE-19 cells and can be regarded as a preventive and therapeutic target for retinal degenerative disease.

Sodium iodate induces ferroptosis in human retinal pigment epithelium ARPE-19 cells

Sodium iodate (SI) is a widely used oxidant for generating retinal degeneration models by inducing the death of retinal pigment epithelium (RPE) cells. However, the mechanism of RPE cell death induced by SI remains unclear. In this study, we investigated the necrotic features of cultured human retinal pigment epithelium (ARPE-19) cells treated with SI and found that apoptosis or necroptosis was not the major death pathway. Instead, the death process was accompanied by significant elevation of intracellular labile iron level, ROS, and lipid peroxides which recapitulated the key features of ferroptosis. Ferroptosis inhibitors deferoxamine mesylate (DFO) and ferrostatin-1(Fer-1) partially prevented SI-induced cell death. Further studies revealed that SI treatment did not alter GPX4 (glutathione peroxidase 4) expression, but led to the depletion of reduced thiol groups, mainly intracellular GSH (reduced glutathione) and cysteine. The study on iron trafficking demonstrated that iron influx was not altered by SI treatment but iron efflux increased, indicating that the increase in labile iron was likely due to the release of sequestered iron. This hypothesis was verified by showing that SI directly promoted the release of labile iron from a cell-free lysate. We propose that SI depletes GSH, increases ROS, releases labile iron, and boosts lipid damage, which in turn results in ferroptosis in ARPE-19 cells.

MiR-132 mediates cell permeability and migration by targeting occludin in high-glucose -induced ARPE-19 cells.

This study investigated the effects and mechanisms of miR-132 related to the permeability and mobility of human retinal pigment epithelium ARPE-19 cells in high-glucose (HG) condition. ARPE-19 cells were cultured in normal and HG condition and identified by immunofluorescence staining. Cell viability was assessed by the MTT assay, cell permeability was assessed by the FITC-dextran assay and cell mobility was assessed by the wound healing assay. Different miRNA and mRNA expression levels were determined by quantitative real-time polymerase chain reaction (RT-qPCR). The expression of tight junction-related proteins was determined by Western blot assay and immunofluorescence. The interaction between occludin and miR-132 was confirmed by a dual-luciferase reporter assay. We revealed that HG-treated ARPE-19 cells exhibited significantly increased miR-132 expression, decreased expression of the tight-junction markers including occludin and E-cadherin, and increased cell mobility and permeability. Occludin is a direct target of miR-132, which could regulate cell viability, mobility and permeability under HG condition through the JAK/STAT3 signaling pathway. These are the first data to suggest that miR-132 may contribute to the progression of diabetic retinopathy (DR) and that targeting the effect of miR-132 on occudin and the JAK/STAT3 pathway could represent a novel effective DR-treatment strategy.

To investigate fit-to-purpose nanocarrier for non-invasive drug delivery to posterior segment of eye

Diseases of the posterior segment of the eye are difficult to treat due to lesser bioavailability of therapeutics at the posterior segment of the eye. Current clinical interventions involve administering drugs via invasive routes (Intravitreal, Retrobulbar, or Peribulbar) that bear the least patient compliance. Several nanocarriers strategies have shown a remarkable potential to deliver the loaded therapeutic to the posterior tissues of the eye. However, no one platform report was available to demarcate the most effective delivery system out of the recommended approaches. This investigation aimed at exploring a suitable and efficient non-invasive topically administrable nanocarriers system for the delivery of the drug to the posterior segment of the eye. Dexamethasone (DEX, a corticosteroid used for ocular inflammation) was selected as a model drug. The nanocarriers were formulated (size ~120 nm) and studied their potential at a common platform to deliver the drug to the posterior segment of the eye. The nanocarriers were analyzed for their in vitro drug release profile in simulated tear fluid (STF) depicting sustained release of DEX up to 24 h, ex-vivo corneal permeability, using excised goat cornea, cytotoxicity potential using human retinal pigment epithelium ARPE-19 cell lines, HET CAM assay to evaluate ocular irritancy, electrical resistance measurement across monolayers of Rabbit corneal epithelial cells SIRC and ARPE-19 cells and stability profiles, real-time qPCR IL-6 gene expression in ARPE-19 inflammation model. Ex-vivo corneal permeability demonstrated that the highest percentage of DEX was permeated by DEX-NLCs and lowest by DEX-SLNs. All the nanocarriers except DEX-CUBs depicted no cytotoxicity in ARPE-19 cells. All the nanocarriers depicted the change in electrical resistance measurement across monolayers of Rabbit corneal epithelial cells SIRC and ARPE-19 cells. They were also found to reduce the levels of IL-6 in gene expression assay depicting successful invitro delivery to ARPE-19 cells. However, only NLCs and NMFs were selected further as they demonstrated better potential to permeate after ex vivo and in vitro permeability studies. Further, in-vivo fluorescence imaging studies in Wistar rats were also performed with coumarin-6 loaded nanocarriers to deduce the effective and suitable candidate to deliver a drug to the posterior segment of the eye with the highest biosafety and permeability.

Monounsaturated oleic acid modulates autophagy flux and upregulates angiogenic factor production in human retinal pigment epithelial ARPE-19 cells

AimsDyslipidemia-associated diabetic retinopathy is featured by macular edema and retinal angiogenesis. This study investigated the in vitro lipotoxicity of free fatty acids and their modulatory roles in regulation of autophagy and angiogenic factor production in cultured human retinal pigment epithelium (RPE) ARPE-19 cells. Main methodsARPE-19 cells were exposed to monounsaturated oleic acid (OA), saturated palmitic acid (PA), or both. Cell viability, cell cycle distribution, migration, and autophagy of the treated cells were monitored. Angiogenic factor production was determined by RT-qPCR and ELISA. Key findingsOA, but not PA, at doses higher than 500 μM significantly induced cytostasis and lipotoxicity in ARPE-19 cells. OA exposure not only markedly enhanced autophagy flux, but also enhanced cell migration, while PA suppressed motility of RPE cells. Meanwhile, OA stimulated de novo synthesis of angiogenic factors including VEGF and bFGF in ARPE-19 cells. Mechanistically, OA treatment stimulated not only AMPK/mTOR/p70S6K signaling, but also induced hyperphosphorylation of MAPK pathway mediators, including ERK, JNK and p38 MAPK, as well as NF-κB activation. Kinase inhibition assays showed that blockade of PI3K/Akt, MAPK and NF-κB pathways prevented the OA-upregulated VEGF transcription and its peptide release. Comparatively, only NF-κB inhibition significantly suppressed bFGF peptide release from ARPE-19 cells. SignificanceOut findings support the OA-exhibited cytostasis, autophagy modulation and angiogenic factor production in RPE cells. This study sheds light on the interrelationship between metabolic disorder and retinopathy and provides molecular strategies for preventing and treating choroidal neovascularization in diabetic retinopathy.

Triptolide protects human retinal pigment epithelial ARPE-19 cells against high glucose-induced cell injury by regulation of miR-29b/PTEN

Oxidative stress and inflammation are necessary pathogenic factors contributing to the aetiology of diabetic retinopathy (DR). Triptolide (TPL) is derived from the traditional Chinese herb lei gong teng with anti-inflammatory, immunosuppressive and antitumor activities. This article was developed to examine the effect of TPL on DR. ARPE-19 cells were pre-treated with TPL and then stimulated by high glucose (HG). We found that TPL treatment enhanced cell viability, decreased apoptosis and ROS production in HG-treated RPE cells. MiR-29b was low-expressed in HG-treated cells, but TPL raised its expression. In addition, the protective activity of TPL towards ARPE-19 cells was attenuated when miR-29b was reduced. By utilising bioinformatics evaluation, PTEN was predicted as a downstream target of miR-29b. Also, TPL obstructed PI3K/AKT signalling pathways in HG-treated ARPE-19 Cells. Taken together, TPL secured ARPE-19 cells from HG-induced oxidative damage via regulating miR-29b/PTEN axis.

VEGF Production Is Regulated by the AKT/ERK1/2 Signaling Pathway and Controls the Proliferation of Toxoplasma gondii in ARPE-19 Cells.

The retina is the primary site of Toxoplasma gondii infection in the eye, and choroidal neovascularization in ocular toxoplasmosis is one of the most important causes of visual impairment. Vascular endothelial growth factor (VEGF) is one of the key regulators of blood vessel development, however, little is known about the mechanisms of T. gondii-induced VEGF production in ocular toxoplasmosis. Here, we investigate the effect of T. gondii on VEGF production regulation in human retinal pigment epithelium ARPE-19 cells and attempted to unveil the underlying mechanism of this event by focusing on the interaction between parasite and the selected host intracellular signaling pathways. T. gondii infection increased the expression of VEGF mRNA and protein in ARPE-19 cells in parasite burden- and infection time-dependent manner. The proportional increase of VEGF upstream regulators, HIF-1α and HO-1, was also observed. T. gondii induced the activation of host p-AKT, p-ERK1/2, and p-p38 MAPK in ARPE-19 cells in a parasite-burden dependent manner. However, VEGF expression decreased after the pre-treatment with PI3K inhibitors (LY294002 and GDC-0941), ERK1/2 inhibitor (PD098059), and p38 MAPK inhibitor (SB203580), but not JNK inhibitor (SP600125), in a dose-dependent manner. The anti-VEGF agent bevacizumab or VEGF siRNA transfection prominently inhibited the activation of p-AKT and p-ERK1/2, but not p-p38 MAPK and JNK1/2 in T. gondii-infected ARPE-19 cells. Bevacizumab treatment or VEGF siRNA transfection significantly inhibited the proliferation of T. gondii tachyzoites in the host cell, dose-dependently, but not invasion of parasites. VEGF-receptor 2 (VEGF-R2) antagonist, SU5416, attenuated VEGF production and tachyzoite proliferation in T. gondii-infected ARPE-19 cells in a dose-dependent manner. Collectively, T. gondii prominently induces VEGF production in ARPE-19 cells, and VEGF and AKT/ERK1/2 signaling pathways mutually regulate each other in T. gondii-infected ARPE-19 cells, but not p38 MAPK and JNK1/2 signaling pathways. VEGF and VEGF-R2 control the parasite proliferation in T. gondii-infected ARPE-19 cells. From this study, we revealed the putative mechanisms for VEGF induction as well as the existence of positive feedback between VEGF and PI3K/MAPK signaling pathways in T. gondii-infected retinal pigment epithelium.

Long non-coding RNA XIST regulates hyperglycemia-associated apoptosis and migration in human retinal pigment epithelial cells

ObjectivePatients with chronic hyperglycemia are at high risk of developing diabetic retinopathy. In this study, we investigated the functional role of long-noncoding RNA (lncRNA) X-inactive specific transcript (XIST) in anin vitro model of diabetic hyperglycemia in human retinal pigment epithelial ARPE-19 cells. MethodARPE-19 cells were cultured in normal glucose (NG) and high-glucose (HG) conditions to mimic hyperglycemia-associated cell apoptosis, migration and XIST expression. XIST was overexpressed in ARPE-19 cells to examine its functions in HG-induced cell apoptosis and migration. The downstream competing target of XIST, human mature microRNA-21-5p (hsa-miR-21-5p) was assessed by dual-luciferase assay and qRT-PCR. Hsa-miR-21-5p was upregulated in XIST-overexpressed ARPE-19 cells to further assess the functional correlation between XIST and hsa-miR-21-5p in hyperglycemia-associated cell apoptosis and migration. ResultsHG insult increased apoptosis, reduced migration and downregulated XIST in ARPE-19 cells. XIST overexpression significantly protected HG insult in ARPE-19 cells, by reducing apoptosis and restoring migration capability. XIST directly bound and inhibited hsa-miR-21-5p expression in HG-insulted ARPE-19 cells. Furthermore, hsa-miR-21-5p upregulation reversed the protective effects of XIST in HG-insulted ARPE-19 cells. ConclusionXIST, likely through competitive binding of hsa-miR-21-5p, provides protection against hyperglycemia-associated injury in human retinal pigment epithelial cells.

C1q/TNF-related Protein 9 Inhibits High Glucose–Induced Oxidative Stress and Apoptosis in Retinal Pigment Epithelial Cells Through the Activation of AMPK/Nrf2 Signaling Pathway

Diabetic retinopathy (DR) is one of the common complications of diabetes mellitus. C1q/TNF-related protein 9 (CTRP9) has been demonstrated to be associated with the progression of diabetes and relative complications. However, its role in DR and underlying action of mechanism are not yet well understood. In the present study, human retinal pigment epithelial ARPE-19 cells were cultured under high concentration of glucose to simulate hyperglycemia condition in vitro. Our results showed that the expression of CTRP9 was significantly decreased in high glucose (HG)–stimulated ARPE-19 cells. CTRP9 overexpression improved HG-caused reduction in cell viability of ARPE-19 cells. CTRP9 overexpression significantly attenuated HG-induced oxidative stress, as proved by decreased levels of reactive oxygen species and malondialdehyde, and increased superoxide dismutase activity. Moreover, CTRP9 also prevented apoptosis in ARPE-19 cells in response to HG stimulation with decreased caspse-3 activity and bax expression, as well as increased bcl-2 expression. In contrast, knockdown of CTRP9 aggravated HG-induced oxidative stress and apoptosis. Furthermore, CTRP9 significantly induced the activation of AMPK/Nrf2 pathway in HG-induced ARPE-19 cells. Notably, inhibiting AMPK or Nrf2 blocked the protective effect of CTRP9 on ARPE-19 cells exposed to HG stimulation. Taken together, our findings suggested a protective effect of CTRP9 on HG-induced ARPE-19 cells and a putative mechanism involving the activation of AMPK/Nrf2 signaling pathway.

Thermosensitive Nanocomposite Hydrogels for Intravitreal Delivery of Cefuroxime.

Endophthalmitis is a rare, but serious, intravitreal inflammatory disorder that can arise after cataract surgery. The intracameral injection of 1 mg cefuroxime (CEF) followed by three-times daily antibiotic topical administration for a week is generally recognized as the routine method of prophylaxis after cataract surgery. This procedure is controversial because of both the low efficacy and the low adherence to therapy by elderly patients. A unique slow release antibiotic intravitreal injection could solve these problems. The objective of the present study was to design ophthalmic nanocomposite delivery systems based on in situ gelling formulations that undergo sol-to-gel transition upon change in temperature to prolong the effect of CEF. Oil in water (O/W) microemulsion (µE) and solid lipid nanoparticles (SLN), obtained with an innovative formulation technology called cold microemulsion dilution, were evaluated as ocular drug delivery systems for CEF. Drug entrapment efficiency up to 80% was possible by esterifying CEF with 1-dodecanol to obtain dodecyl-CEF (dCEF). Both dCEF-loaded SLN and µE were then added with Pluronic®F127 (20% w/v) to obtain a nanocomposite hydrogel-based long acting system. The prepared thermosensitive formulations were evaluated for their physical appearance, drug content, gelation temperature, injectability and rheological properties, in vitro release studies and stability studies. Moreover, cell proliferation assays on human retinal pigment epithelial ARPE-19 cells were performed to evaluate the influence of this innovative system on the cellular viability. In addition, minimal inhibitory concentration (MIC) was assessed for both CEF and dCEF, revealing the need of dCEF hydrolysis for the antimicrobial activity. Although further experimental investigations are required, the physico-chemical characterization of the nanocomposite hydrogels and the preliminary in vitro release studies highlighted the potential of these systems for the sustained release of CEF.

RETRACTED: Ginsenoside Rg1 protects human retinal pigment epithelial ARPE-19 cells from toxicity of high glucose by up-regulation of miR-26a

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editor-in-Chief. Given the comments of Dr Elisabeth Bik regarding this article “… the Western blot bands in all 400+ papers are all very regularly spaced and have a smooth appearance in the shape of a dumbbell or tadpole, without any of the usual smudges or stains. All bands are placed on similar looking backgrounds, suggesting they were copy/pasted from other sources, or computer generated”, the journal requested the authors to provide the raw data. However, the authors were not able to fulfil this request and therefore the Editor-in-Chief decided to retract the article.

The Coenzyme Q10 (CoQ10) as Countermeasure for Retinal Damage Onboard the International Space Station: the CORM Project

Cells, tissues and organs of astronauts aboard the International Space Station (ISS) are exposed to the damaging effects of microgravity and cosmic radiation. Space Agencies are forced to find effective therapeutic countermeasures to safeguard astronauts’ health. Since retina is one of the most vulnerable target, we undertook a project entitled The Coenzyme Q10 (CoQ10) as countermeasure for retinal damage onboard the International Space Station: the CORM project, funded by the Italian Space Agency (ASI) and launched in the summer 2017. We selected CoQ10 as promising candidate drug, having previously first demonstrated its direct antiapoptotic property due to its ability to inhibit mitochondrial depolarization. Beside apoptosis prevention, the parameters we are measuring to evaluate the therapeutic effectiveness of CoQ10 are attenuation of cytoskeleton modifications, lowering of telomeric DNA damages, and exome and whole transcriptome alterations. Here, we present preliminary on-ground experiments that have been carried out in human retinal pigment epithelial ARPE-19 cells and the experimental design of the CORM experiment aboard the ISS. The results obtained by the CORM project will pave the way to countermeasures for astronauts who will face long-term missions.

Novel YAP1 Activator, Identified by Transcription-Based Functional Screen, Limits Multiple Myeloma Growth.

Yes-associated protein 1 (YAP1) interacts with numerous transcription factors, including TEA-domain family proteins (TEAD) and p73. YAP1 is negatively regulated by the tumor suppressor Hippo pathway. In human cancers, the deregulation of the Hippo pathway and YAP1 gene amplification lead to the activation of YAP1, which induces epithelial-mesenchymal transition (EMT) and drug resistance. YAP1 inhibitors are expected to be useful in cancer therapy. On the other hand, in certain cancers, YAP1 upregulates p73-dependent gene transcription and behaves as a tumor suppressor. Moreover, as YAP1 regulates self-renewal and differentiation of tissue stem cells and plays an important role in tissue homeostasis, YAP1 activators may contribute to the regenerative medicine. With this in our mind, we screened for YAP1 activators by using human retinal pigment epithelial ARPE-19 cells expressing the TEAD-responsive fluorescence reporter under the coexpression of YAP1. From an extensive chemical compound library (n = 18,606) 47 candidate YAP1 activators were identified. These compounds were characterized to determine whether this assay provides bona fide YAP1 activators. Importantly, one YAP1 activator was effective against the human multiple myeloma IM-9 cells and chronic myeloid leukemia K562 cells.Implications: YAP1 activation limits growth, induces apoptosis, and may be useful at suppressing hematological cancers. Mol Cancer Res; 16(2); 197-211. ©2017 AACR.