Cytotoxicity In ARPE-19 Cells Research Articles

Deletion of Specific Conserved Motifs from the N-Terminal Domain of αB-Crystallin Results in the Activation of Chaperone Functions.

Smaller oligomeric chaperones of α-crystallins (αA- and αB-) have received increasing attention due to their improved therapeutic potential in preventing protein aggregating diseases. Our previous study suggested that deleting 54–61 residues from the N-terminal domain (NTD) of αB-crystallin (αBΔ54–61) decreases the oligomer size and increases the chaperone function. Several studies have also suggested that NTD plays a significant role in protein oligomerization and chaperone function. The current study was undertaken to assess the effect of deleting conserved 21–28 residues from the activated αBΔ54–61 (to get αBΔ21–28, Δ54–61) on the structure–function of recombinant αBΔ21–28, Δ54–61. The αBΔ21–28, Δ54–61 mutant shows an 80% reduction in oligomer size and 3- to 25-fold increases in chaperone activity against model substrates when compared to αB-WT. Additionally, the αB∆21–28, ∆54–61 was found to prevent β-amyloid (Aβ1–42) fibril formation in vitro and suppressed Aβ1–42-induced cytotoxicity in ARPE-19 cells in a more effective manner than seen with αB-WT or αB∆54–61. Cytotoxicity and reactive oxygen species (ROS) detection studies with sodium iodate (SI) showed that the double mutant protein has higher anti-apoptotic and anti-oxidative activities than the wild-type or αB∆54–61 in oxidatively stressed cells. Our study shows that the residues 21–28 and 54–61 in αB-crystallin contribute to the oligomerization and modulate chaperone function. The deletion of conserved 21–28 residues further potentiates the activated αBΔ54–61. We propose that increased substrate affinity, altered subunit structure, and assembly leading to smaller oligomers could be the causative factors for the increased chaperone activity of αBΔ21–28, Δ54–61.

Size-Dependent Cytotoxicity and Reactive Oxygen Species of Cerium Oxide Nanoparticles in Human Retinal Pigment Epithelia Cells.

PurposeThe use of cerium oxide nanoparticles (CeO2 NPs), a lanthanide element oxide and bivalent compound, has been growing continuously in industry and biomedicine. Due to their wide application, the potential human health problems of CeO2 NPs have attracted attention, but studies on the toxicity of this compound to human eyes are lacking. This study investigated the cytotoxicity and reactive oxygen species (ROS) of CeO2 NPs in human retinal pigment epithelial cells (ARPE-19 cells).MethodsUsing the transmission electron microscope (TEM), the size distribution and shape of CeO2 NPs were characterized. To explore the effect of CeO2 NP size on ophthalmic toxicity in vitro, three sizes (15, 30 and 45 nm) of CeO2 NPs were investigated using ATP content measurement, LDH release measurement and cell proliferation assay in ARPE-19 cells. ROS values and mitochondrial membrane potential depolarization were evaluated by H2DCF-DA staining and JC-1 staining. Morphology changes were detected using a phase-contrast microscope.ResultsThe cytotoxicity of 15 nm CeO2 NPs was found to be the highest and hence was further explored. Treatment with 15 nm CeO2 NPs caused the morphology of ARPE-19 cells to change in a dose- and time-dependent manner. Moreover, the treatment induced excessive ROS generation and mitochondrial membrane potential depolarization. In addition, cytotoxicity was attenuated by the application of a ROS scavenger N-acetyl-L- cysteine (NAC).ConclusionCeO2 NPs induced cytotoxicity in ARPE-19 cells and excessive production of ROS and decreasing mitochondrial membrane potential. The Overproduction of ROS partially contributes to CeO2 NP-induced cytotoxicity.

Anti-Inflammatory Effects of Resveratrol on Human Retinal Pigment Cells and a Myopia Animal Model.

Resveratrol is a key component of red wine and other grape products. Recent studies have characterized resveratrol as a polyphenol, and shown its beneficial effects on cancer, metabolism, and infection. This study aimed to obtain insights into the biological effects of resveratrol on myopia. To this end, we examined its anti-inflammatory influence on human retinal pigment epithelium cells and in a monocular form deprivation (MFD)-induced animal model of myopia. In MFD-induced myopia, resveratrol increased collagen I level and reduced the expression levels of matrix metalloproteinase (MMP)2, transforming growth factor (TGF)-β, and nuclear factor (NF)-κB expression levels. It also suppressed the levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β. Resveratrol exhibited no significant cytotoxicity in ARPE-19 cells. Downregulation of inflammatory cytokine production, and inhibition of AKT, c-Raf, Stat3, and NFκB phosphorylation were observed in ARPE-19 cells that were treated with resveratrol. In conclusion, the findings suggest that resveratrol inhibits inflammatory effects by blocking the relevant signaling pathways, to ameliorate myopia development. This may make it a natural candidate for drug development for myopia.

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.

Silver Nanoparticle-Induced Apoptosis in ARPE-19 Cells Is Inhibited by Toxoplasma gondii Pre-Infection Through Suppression of NOX4-Dependent ROS Generation.

PurposeExternal and internal stimuli easily affect the retina. Studies have shown that cells infected with Toxoplasma gondii are resistant to multiple inducers of apoptosis. Nanoparticles (NPs) have been widely used in biomedical fields; however, little is known about cytotoxicity caused by NPs in the retina and the modulators that inhibit nanotoxicity.Materials and MethodsARPE-19 cells from human retinal pigment epithelium were treated with silver nanoparticles (AgNPs) alone or in combination with T. gondii. Then, the cellular toxicity, apoptosis, cell cycle analysis, autophagy, ROS generation, NOX4 expression, and MAPK/mTOR signaling pathways were investigated. To confirm the AgNP-induced cytotoxicity in ARPE-19 cells and its modulatory effects caused by T. gondii infection, the major experiments carried out in ARPE-19 cells were performed again using human foreskin fibroblast (HFF) cells and bone marrow-derived macrophages (BMDMs) from NOX4−/− mice.ResultsAgNPs dose-dependently induced cytotoxicity and cell death in ARPE-19 cells. Apoptosis, sub-G1 phase cell accumulation, autophagy, JNK phosphorylation, and mitochondrial apoptotic features, such as caspase-3 and PARP cleavages, mitochondrial membrane potential depolarization, and cytochrome c release into the cytosol were observed in AgNP-treated cells. AgNP treatment also increased the Bax, Bik, and Bim protein levels as well as NOX4-dependent ROS generation. However, T. gondii-infected ARPE-19 cells inhibited AgNP-induced apoptosis, JNK phosphorylation, sub-G1 phase cell accumulation, autophagy, NOX4-mediated ROS production, and mitochondrial apoptosis. Furthermore, mitochondrial apoptosis was found in AgNP-treated HFF cells and BMDMs, and AgNP-induced mitochondrial apoptosis inhibition via NOX4-dependent ROS suppression in T. gondii pre-infected HFF cells and BMDMs was also confirmed.ConclusionAgNPs induced mitochondrial apoptosis in human RPE cells combined with cell cycle dysregulation and autophagy; however, these effects were significantly inhibited by T. gondii pre-infection by suppression of NOX4-mediated ROS production, suggesting that T. gondii is a strong inhibitory modulator of nanotoxicity in in vitro models.

PARTÍCULAS DE QUITOSANO/CARRAGENINA/LISOZIMA: SÍNTESIS,CARACTERIZACIÓN Y ACTIVIDAD ANTIFÚNGICA CONTRAAspergillus parasiticus

In this study, particles of chitosan-carrageenan (Cs-Crg) and chitosan-carrageenan-lysozyme (CS-Crg-LZ) were synthesized by ionic complexation. The particles were analyzed by atomic force microscopy, dynamic light scattering and FT-IR, and the percentage of association of lysozyme was determined. The biological activity of the particles was evaluated by viability assays of Aspergillus parasiticus spores and cytotoxicity in ARPE-19 cells. The effect on subcellular structures was analyzed by fluorescence microscopy. The addition of lysozyme reduced the size of the particles. The size and Z potential of the synthesized particles were 725±5.5 and 250±8.1 nm and 28.7±1.0 and 21.6±0.8 mV for CS-Crg and CS-Crg-LZ, respectively. CS-Crg-LZ and CS-Crg particles exhibited a higher (p<0.05) inhibitory effect on the viability of A. parasiticus with respect to control, which increased proportionally to the particles concentration. None of the particles showed a mutagenic effect and they did not present cytotoxicity in ARPE-19 cells; likewise, no changes were observed in cell morphology with respect to control, observing normal structures in the actin cytoskeleton and in the DNA structure. These results show that chitosan-based particles are a feasible and safe option for the control of pathogenic fungi of agricultural-food interest.

Tanshinone IIA Inhibits VEGF Secretion and HIF-1α Expression in Cultured Human Retinal Pigment Epithelial Cells under Hypoxia

ABSTRACTPurpose: The current work intends to study the activity of tanshinone IIA on secretion of vascular endothelial growth factor (VEGF) and expression of hypoxia inducible factor 1α (HIF-1α) in human retinal pigment epithelial cells (ARPE-19 cells) under hypoxic condition.Methods: The cytotoxicity of tanshinone IIA was tested in ARPE-19 cells by MTT assay. ARPE-19 cells were incubated with different concentrations of cobalt chloride (100, 150, and 200 µM) for 12 h, and levels of expressed HIF-1α and secreted VEGF were quantified through Western blot and ELISA, respectively. Further, ARPE-19 cells were pretreated for 1 h with different concentrations of tanshinone IIA (5, 10, 15, and 18 µM). After 1 h, the cells were subjected to hypoxic condition using 150 µM cobalt chloride for 12 h in the presence and absence of tanshinone IIA. The cells were then harvested, and the secreted VEGF and expressed HIF-1α was studied.Results: Tanshinone IIA at concentrations of 5, 10, 15, and 18 μM did not show cytotoxicity in ARPE-19 cells. Chemical hypoxia induced by cobalt chloride caused a significant increase in VEGF level in a dose-dependent manner, and HIF-1α expression peaked at 150 µM. Based on the data, cobalt chloride concentration was maintained at 150 μM for further studies. Tanshinone IIA decreased the level of HIF-1α and VEGF secretion in a dose-dependent manner under hypoxic condition.Conclusion: Tanshinone IIA could be explored as a new potential candidate for treating wet AMD.

Induction of Activating Transcription Factor 6 via Activation of ERK and ROS-P38 MAPK is Related to Methylglyoxal-Induced Cytotoxicity in Human Retinal Pigment Epithelial Cells

Methylglyoxal (MGO), a reactive α-oxoaldehyde produced by glucose metabolism, is elevated in several diabetic complications, including diabetic retinopathy. The breakdown of retinal pigment epithelial cells is implicated in the progression of diabetic retinopathy. Increased concentrations of MGO lead to retinal pigment epithelial cell death. In this study, we investigated the involvement of activating transcription factor 6 (ATF6) in MGO-mediated cytotoxicity in ARPE-19 cells. In response to high concentrations of MGO, unfolded protein response-related ATF6 was induced. Interestingly, the MGO also induced the generation of reactive oxygen species (ROS) and the phosphorylation of ERK and p38 MAPK. The induction of ATF6 was inhibited by ERK-specific and p38 MAPK-specific inhibitors (U0126 and SB202190) and by NAC, a well-known ROS scavenger. NAC also attenuated the phosphorylation of p38 MAPK. MGO induced cytotoxicity in the ARPE-19 cells, which was ameliorated by the inhibition of the ERK, p38 MAPK, and ROS pathways. Furthermore, the MGO-mediated cytotoxicity was inhibited by ATF6 siRNA. Taken together, these results clearly show that the induction of ATF6 via the ERK and ROS-p38 MAPK pathways is implicated in MGO-induced cytotoxicity in ARPE-19 cells.

Methylglyoxal, a reactive glucose metabolite, enhances autophagy flux and suppresses proliferation of human retinal pigment epithelial ARPE-19 cells

Methylglyoxal (MGO), a glycolytic metabolite, induces oxidative injury and apoptotic cell death that play a pathogenetic role in age-related macular degeneration (AMD). This study examined the impact of MGO on cell proliferation and autophagy flux in retinal pigment epithelium (RPE) ARPE-19 cells and elucidated the underlying mechanism. Short-term MGO exposure suppressed cell proliferation without induction of apoptotic cell death, increased production of reactive oxygen species, and potentiated H2O2-exhibited cytotoxicity in ARPE-19 cells. Conversely, pretreatment with N-acetylcysteine, a ROS scavenger, and aminoguanidine, an MGO blocker, prevented MGO-induced growth retardation. MGO significantly enhanced autophagy flux and increased intracellular accumulation of autophagosomes, which was functionally confirmed by addition of autophagy enhancer or inhibitors. Signaling kinetic observation indicated that MGO remarkably triggered phosphorylation of Akt, ERK1/2, p38 MAPK, and JNK1/2. Blockade of kinase activity demonstrated that the hyperphosphorylation of Akt, ERK1/2, JNK, and p38 MAPK were all involved in the MGO-enhanced autophagy and growth-arresting effect in ARPE-19 cells. Moreover, pretreatment with autophagic flux inhibitors including 3-methyladenine, bafilomycin A, and chloroquine effectively ameliorated MGO- but not H2O2-mediated ARPE-19 cytotoxicity. In conclusion, modulation of autophagy flux activity by using autophagic or kinase inhibitors may be an applicable modality to treat AMD.

Hydrophilic Prodrug Approach for Reduced Pigment Binding and Enhanced Transscleral Retinal Delivery of Celecoxib

Transscleral retinal delivery of celecoxib, an anti-inflammatory and anti-VEGF agent, is restricted by its poor solubility and binding to the melanin pigment in choroid-RPE. The purpose of this study was to develop soluble prodrugs of celecoxib with reduced pigment binding and enhanced retinal delivery. Three hydrophilic amide prodrugs of celecoxib, celecoxib succinamidic acid (CSA), celecoxib maleamidic acid (CMA), and celecoxib acetamide (CAA) were synthesized and characterized for solubility and lipophilicity. In vitro melanin binding to natural melanin (Sepia officinalis) was estimated for all three prodrugs. In vitro transport studies across isolated bovine sclera and sclera-choroid-RPE (SCRPE) were performed. Prodrug with the highest permeability across SCRPE was characterized for metabolism and cytotoxicity and its in vivo transscleral delivery in pigmented rats. Aqueous solubilities of CSA, CMA, and CAA were 300-, 182-, and 76-fold higher, respectively, than celecoxib. Melanin binding affinity and capacity were significantly lower than for celecoxib for all three prodrugs. Rank order for the % in vitro transport across bovine sclera and SCRPE was CSA > CMA ~ CAA ~ celecoxib, with the transport being 8-fold higher for CSA than celecoxib. CSA was further assessed for its metabolic stability and in vivo delivery. CSA showed optimum metabolic stability in all eye tissues with only 10-20% conversion to parent celecoxib in 30 min. Metabolic enzymes responsible for bioconversion included amidases, esterase, and cytochrome P-450. In vivo delivery in pigmented BN rats showed that CSA had 4.7-, 1.4-, 3.3-, 6.0-, and 4.5-fold higher delivery to sclera, choroid-RPE, retina, vitreous, and lens than celecoxib. CSA has no cytotoxicity in ARPE-19 cells in the concentration range of 0.1 to 1000 μM. Celecoxib succinamidic acid, a soluble prodrug of celecoxib with reduced melanin binding, enhances transscleral retinal delivery of celecoxib.