Comparative Determination of Cytotoxicity of Sub-10 nm Copper Nanoparticles to Prokaryotic and Eukaryotic Systems.

Copper nanoparticles demonstrate antibacterial activity, but their toxicity to eukaryotic systems is less understood. Here, we carried out a comparative study to determine the biocompatibility and cytotoxicity of sub-10 nm copper nanoparticles to a variety of biological systems, including prokaryotic cells (Escherichia coli), yeast, mammalian cell lines (HEK293T, PC12), and zebrafish embryos. We determined the bearing threshold for the cell-death-inducing concentration of copper nanoparticles by probing cell growth, viability, as well as embryological features. To exclude the partial toxicity effect from the remnant reactants, we developed a purification approach using agarose gel electrophoresis. Purified CuONP solution inhibits bacterial growth and causes eukaryotic cell death at 170 and 122.5 ppm (w/w) during the 18 h of treatment, respectively. CuONP significantly reduces the pigmentation of retina pigmented epithelium of zebrafish embryos at 85 ppm. The cytotoxicity of CuONP in eukaryotic cells could arise from the oxidative stress induced by CuONP. This result suggests that small copper nanoparticles exert cytotoxicity in both prokaryotic and eukaryotic systems, and therefore, caution should be used to avoid direct contact of copper nanoparticles to human tissues considering the potential use of copper nanoparticles in the clinical setting.

ApoA-I Mimetic Peptide 4F Reduces Age-Related Lipid Deposition in Murine Bruch's Membrane and Causes Its Structural Remodeling.

PURPOSE: Accumulation of lipoprotein-derived lipids including esterified and unesterified cholesterol in Bruch's membrane of human eyes is a major age-related change involved in initiating and sustaining soft drusen in age-related macular degeneration (AMD). The apolipoprotein (apo) A-I mimetic peptide 4F is a small anti-inflammatory and anti-atherogenic agent, and potent modifier of plasma membranes. We evaluated the effect of intravitreally-injected 4F on murine Bruch's membrane. METHODS: We tested single intravitreal injections of 4F doses (0.6 µg, 1.2 µg, 2.4 µg, and placebo scrambled peptide) in ApoEnull mice ≥10 months of age. After 30 days, mice were euthanized. Eyes were processed for either direct immunofluorescence detection of esterified cholesterol (EC) in Bruch's membrane whole mounts via a perfringolysin O-based marker linked to green fluorescent protein or by transmission electron microscopic visualization of Bruch's membrane integrity. Fluorescein isothiocyanate-conjugated 4F was traced after injection. RESULTS: All injected eyes showed a dose-dependent reduction of Bruch's membrane EC with a concomitant ultrastructural improvement compared to placebo treated eyes. At a 2.4 µg dose of 4F, EC was reduced on average by ~60% and Bruch's membrane returned to a regular pentalaminar structure and thickness. Tracer studies confirmed that injected 4F reached intraocular targets. CONCLUSION: We demonstrated a highly effective pharmacological reduction of EC and restoration of Bruch's membrane ultrastructure. The apoA-I mimetic peptide 4F is a novel way to treat a critical AMD disease process and thus represents a new candidate for treating the underlying cause of AMD.

[Rate of visual recovery after macular hole surgery with intraoperative optical coherence tomography and visualization of the internal limiting membrane]. / Tempy vosstanovleniia ostroty zreniia posle khirurgicheskogo lecheniia makuliarnykh razryvov s intraoperatsionnym primeneniem opticheskoi kogerentnoi tomografii i razlichnykh metodov vizualizatsii vnutrennei pogranichnoi membrany.

Currently, multiple techniques exist to repair a macular hole, but the functional result may be largely affected by the use of dyes during surgery. With our original visualization methods, one is able to remove the internal limiting membrane (ILM) without staining, and thus to avoid the toxic effect of dyes. AIM: to compare anatomical and functional results of surgical closure of large macular holes with or without ILM staining. MATERIAL AND METHODS: A total of 160 patients (190 eyes) were divided into 2 groups. Patients from group 1 (60 eyes) were subjected to surgery that involved the use of a dye, while in group 2 (130 eyes) ILM was not performed. Anatomical and functional results of the two groups were then compared. RESULTS: The next day after surgery, a large improvement in the best corrected visual acuity - of 3 lines or more - was found in 28 controls (46.6%) and 98 patients from the main group (75.4%). There was no significant change in 24 and 27 patients, respectively (40.0% and 20.7%). The remaining 8 and 5 patients (13.4% and 3.9%) deteriorated by 3 lines or more. CONCLUSION: Stain-free removal of the ILM under green-yellow light favours rapid recovery of visual acuity in patients with macular holes. Anatomical reconstruction of the foveola, including complete approximation of the hole margins and keeping the defect closed until the end of the operation, is controlled through a built-in optical coherence tomograph ensuring high anatomical and functional results.

cAMP Stimulates Transepithelial Short-Circuit Current and Fluid Transport Across Porcine Ciliary Epithelium.

Purpose: To investigate the effects of cAMP on transepithelial electrical parameters and fluid transport across porcine ciliary epithelium. Methods: Transepithelial electrical parameters were determined by mounting freshly isolated porcine ciliary epithelium in a modified Ussing chamber. Similarly, fluid movement across intact ciliary body was measured with a custom-made fluid flow chamber. Results: Addition of 1, 10, and 100 µM 8-Br-cAMP (cAMP) to the aqueous side (nonpigmented ciliary epithelium, NPE) induced a sustained increase in short-circuit current (Isc). Addition of niflumic acid (NFA) to the aqueous surface effectively blocked the cAMP-induced Isc stimulation. The administration of cAMP to the stromal side (pigmented ciliary epithelium, PE) triggered a significant stimulation of Isc only at 100 µM. No additive effect was observed with bilateral application of cAMP. Likewise, forskolin caused a significant stimulation of Isc when applied to the aqueous side. Concomitantly, cAMP and forskolin increased fluid transport across porcine ciliary epithelium, and this stimulation was effectively inhibited by aqueous NFA. Depleting Cl- in the bathing solution abolished the baseline Isc and inhibited the subsequent stimulation by cAMP. Pretreatment with protein kinase A (PKA) blockers (H89/KT5720) significantly inhibited the cAMP- and forskolin-induced Isc responses. Conclusions: Our results suggest that cAMP triggers a sustained stimulation of Cl- and fluid transport across porcine ciliary epithelium; Cl- channels in the NPE cells are potentially a cellular site for this PKA-sensitive cAMP-mediated response.

Control of fibrotic changes through the synergistic effects of anti-fibronectin antibody and an RGDS-tagged form of the same antibody.

TGF-ß and myofibroblasts play a key role in fibrosis, characterized by aberrant synthesis and deposition of extracellular matrix (ECM) proteins, such as fibronectin (Fn) and collagen type I. There are two major roles played by integrins in the fibrotic pathology: (i) Fn-integrin interaction, coupled with cytokines like TGF-ß, facilitates the self-polymerization of Fn and regulates cell-matrix fibrillar adhesions, thereby promoting fibrillogenesis; (ii) Integrin interaction with an RGD (arginine-glycine-aspartic) consensus sequence in the latent TGF-ß, resulting in its activation. This study describes an anti-fibrotic strategy using a combination of two antibodies: Fn52 (targeted against the N-terminal 30 kDa region of fibronectin, a major site for Fn self-association), and its engineered form, Fn52RGDS (which binds to integrins). Interestingly, a synergistic effect of the cocktail in causing a decline in fibrotic features was confirmed in the context of fibrotic posterior capsular opacification (PCO), mediated by the lens epithelial cells (left behind after cataract surgery). Inclusion of Fn52RGDS to Fn52 aids in better diffusion of the antibodies; such combination therapies could be useful in the context of pathologies involving extensive remodeling of the fibronectin matrix, where the thick ECM offers a major challenge for efficient drug delivery.

Apelin-13 induces proliferation, migration, and collagen I mRNA expression in human RPE cells via PI3K/Akt and MEK/Erk signaling pathways.

PURPOSE: Our previous study showed that apelin was increased in the vitreous and fibrotic membranes of patients with proliferative diabetic retinopathy (PDR) in vivo, which suggested that apelin may be involved in the development of PDR. In this study, we investigated whether the expression of apelin was upregulated in human retinal pigment epithelial (RPE) cells in vitro under high glucose conditions. Furthermore, to explore the role of apelin in RPE cells, we investigated the effect of exogenous recombinant apelin on proliferation, migration, and collagen I (a major component of extracellular matrix molecules, associated with PDR) expression and investigated the signaling pathways involved in these processes. METHODS: Real-time PCR and western blot were performed to determine the apelin expression in ARPE-19 cells under high glucose conditions. Exogenous recombinant apelin was used to study the effect of apelin on ARPE-19 cells in vitro. Cell proliferation, migration, and collagen I expression were assessed using an MTT assay, a transwell assay, and real-time PCR analysis. LY294002 (an inhibitor of phosphatidylinositol 3-kinase) and PD98059 (an inhibitor of mitogen-activated protein kinase) were used to help to determine the apelin signaling mechanism. RESULTS: High glucose upregulated apelin expression in RPE cells. Exogenous recombinant apelin activated protein kinase B (Akt) and extracellular signal-regulated kinase (Erk) phosphorylation and promoted proliferation, migration, and collagen I expression in RPE cells. Pretreatment with LY294002 and PD98059 abolished apelin-induced activation of Akt and Erk, proliferation, and collagen I expression. Apelin-induced migration was partially blocked by pretreatment with LY294002 and PD98059. CONCLUSIONS: The expression of apelin was upregulated under high glucose conditions in RPE cells in vitro. Exogenous recombinant apelin increased the biologic activity of RPE cells, as well as the expression of collagen I. Apelin promoted proliferation, migration, and collagen I expression through the PI3K/Akt and MEK/Erk signaling pathways in RPE cells. From these results, we revealed the role of apelin in regulating proliferation, migration, and collagen I expression in RPE cells and the signaling mechanism under these processes, which suggested that apelin may play a profibrotic role in the development of PDR.

[Prevention and treatment of age-related macular degeneration by extract of Fructus lycii and its constituents lutein/zeaxanthin: an in vive and in vitro experimental research].

OBJECTIVE: To investigate the in vivo inhibition of extract of Fructus lycii (FL) on the expressions of cathepsin B (Cat B) and cystatin C (Cys C) in high-fat diet and hydroquinone (HQ) induced model mice with age-related macular degeneration (AMD), and to explore the in vitro effects of lutein and zeaxanthin on hydrogen peroxide (H2O2,) induced expressions of matrix metalloproteinase 2 (MMP-2) and tissue inhibitor of metalloproteinase 2 (TIMP-2) on ARPE-19 cells. METHODS: Fifty female 8-month-old C57BL/6 mice were recruited in this research. Ten mice fed with regular diet was taken as the age control group. The rest 40 mice were fed with high fat diet for 6 months, followed by adding HQ (0. 8%) in the drinking water for 3 consecutive months. Then the modeled mice were randomly divided into the model control group (n =10), the high (at the daily dose of 3.75 g/kg), middle (at the daily dose of 2.50 g/kg), and low dose (at the daily dose of 1.25 g/kg) FL groups, 10 in each group. The extract of FL at each dose was respectively administered to mice by gastrogavage for 3 successive months. By the end of the experiment, the mice were killed and their eyeballs were removed. The protein expressions of Cat B and Cys C were observed by immunohistochemical assay. The mRNA and protein expressions of Cat B and Cys C were detected by real-time PCR and Western blot respectively. The drug concentrations of H2O2, lutein, and zeaxanthin were screened and detected using the activity of cell proliferation. The protein expressions of MMP-2 and TIMP-2 were detected using Western blot. RESULTS: Compared with the age control group, the mRNA and protein expressions of Cat B and Cys C were significantly higher in the in vivo model control group (P <0.05, P <0.01). The mRNA expressions of Cat B and Cys C were weaker in the middle and high dose FL groups than in the model control group (P <0. 05, P <0. 01). In in vitro cells, lutein and zeaxanthin could down-regulate the protein expressions of MMP-2 and TIMP-2 in H202 induced ARPE-19 cells (P <0. 05, P <0. 01). CONCLUSIONS: Extract of FL could down-regulate the high protein expressions of Cat B and Cys C in high-fat diet and HQ induced model mice. Lutein and zeaxanthin could down-regulate the protein expressions of MMP-2 and TIMP-2 in H202 induced ARPE-19 cells.

Gold nanoparticles disrupt zebrafish eye development and pigmentation.

Systematic toxicological study is still required to fully understand the hazard potentials of gold nanoparticles (AuNPs). Because their biomedical applications are rapidly evolving, we investigated developmental toxicity of AuNPs in an in vivo embryonic zebrafish model at exposure concentration ranges from 0.08 to 50mg/l. Exposure of zebrafish embryos to 1.3 nm AuNPs functionalized with a cationic ligand, N,N,N-trimethylammoniumethanethiol (TMAT-AuNPs), resulted in smaller malpigmented eyes. We determined that TMAT-AuNPs caused a significant increase of cell death in the eye, which was correlated with an increase in gene expression of p53 and bax. Expression patterns of key transcription factors regulating eye development (pax6a, pax6b, otx2, and rx1) and pigmentation (sox10) were both repressed in a concentration-dependent manner in embryos exposed to TMAT-AuNPs. Reduced spatial localization of pax6a, rx1, sox10, and mitfa was observed in embryos by whole-mount in situ hybridization. The swimming behavior of embryos exposed to sublethal concentrations of TMAT-AuNPs showed hypoactivity, and embryos exhibited axonal growth inhibition. Overall, these results demonstrated that TMAT-AuNPs disrupt the progression of eye development and pigmentation that continues to behavioral and neuronal damage in the developing zebrafish.

Synthesis of antioxidants for prevention of age-related macular degeneration.

Photooxidation of A2E may be involved in diseases of the macula, and antioxidants could serve as therapeutic agents for these diseases. Inhibitors of A2E photooxidation were prepared by Mannich reaction of the antioxidant quercetin. These compounds contain water-solubilizing amine groups, and several were more potent inhibitors of A2E photooxidation than quercetin.

Effects of tamsulosin and silodosin on isolated albino and pigmented rabbit iris dilators: possible mechanism of intraoperative floppy-iris syndrome.

PURPOSE: To determine the mechanism of intraoperative floppy-iris syndrome (IFIS) by examining the binding affinity of tamsulosin and silodosin to α-receptors and melanin pigment using control and α(2)-blocker chronically administered in rabbit models. SETTING: Department of Ophthalmology, Kitasato University School of Medicine, Kanagawa, Japan. DESIGN: Experimental study. METHODS: The study was performed in isolated albino and pigmented rabbit iris dilators using pharmacologic and morphologic examinations. RESULTS: For pharmacologic examinations, the mean pK(B) values (pK(B) = -log K(B), where -log K(B) is the equilibrium dissociation constant of the antagonist-receptor complex) of tamsulosin in albino and pigmented rabbits were 9.10 and 8.08 and those of silodosin, 10.3 and 8.11, respectively. The pK(B) values of tamsulosin and silodosin in albino rabbits were significantly higher than in pigmented rabbits. In the isolated rabbit iris dilator, the maximum contraction evoked by 10(-3) mol/L phenylephrine gradually decreased by repetitive application in the chronic α-blocker-administered models. For morphologic examinations, the sizes of the pigment granules of pigment epitheliums for the α-blocker-administered models were irregular. The shape of shared nucleus of dilator muscles and pigment epitheliums changed to lobular, and the dilator muscle layer was thinner than in the control. CONCLUSIONS: The high affinity of α-blockers for α(1)-adrenoreceptors is important in the analysis of the mechanism of IFIS. However, IFIS should not be attributed to long-term binding with receptors alone; the drug-melanin interaction causing dilator muscle atrophy is probably the other important factor in the mechanism of IFIS.

TNF-α promotes human retinal pigment epithelial (RPE) cell migration by inducing matrix metallopeptidase 9 (MMP-9) expression through activation of Akt/mTORC1 signaling.

Tumor necrosis factor-alpha (TNF-α) promotes in vitro retinal pigment epithelial (RPE) cell migration to initiate proliferative vitreoretinopathy (PVR). Here we report that TNF-α promotes human RPE cell migration by inducing matrix metallopeptidase 9 (MMP-9) expression. Inhibition of MMP-9 by its inhibitor or its neutralizing antibody inhibited TNF-α-induced in vitro RPE cell migration. Reversely, exogenously-added active MMP-9 promoted RPE cell migration. Suppression Akt/mTOR complex 1(mTORC1) activation by LY 294002 and rapamycin inhibited TNF-α-mediated MMP-9 expression. To introduce a constitutively active Akt (CA-Akt) in cultured RPE cells increased MMP-9 expression, and to block mTORC1 activation by rapamycin inhibited its effect. RNA interference (RNAi)-mediated silencing of SIN1, a key component of mTOR complex 2 (mTORC2), had no effect on MMP-9 expression or secretion. In conclusion, this study suggest that TNF-α promotes RPE cell migration by inducing MMP-9 expression through activation of Akt/ mTORC1, but not mTORC2 signaling.

Acute posterior multifocal placoid pigment epitheliopathy: role of TNF blocker in severe cases.

PURPOSE: The aim of this study was to describe cases with severe acute posterior multifocal placoid pigment epitheliopathy treated with tumor necrosis factor (TNF) blocker [Remicade (infliximab)] as regards the improvement of visual acuity, contralateral affection, and prevention of recurrence. METHODS: We analyzed patients with severe acute posterior multifocal placoid pigment epitheliopathy confirmed by fluorescein fundus angiography as regards the demographic data (age, sex) and the most relevant clinical findings such as, visual acuity, retinal condition, association with other systemic diseases, and response to TNF blocker. RESULTS: Eight patients were included in this study, 5 (62.5%) of them had unilateral lesion and 3 (37.5%) had bilateral lesions. The mean age of the patients was 29.5 ± 8.5 years (range, 19 to 42 years). Of them, 3 (37.5%) were women and 5 (62.5%) were men. All patients received TNF blocker (Remicade) in 4 doses (infusion of 100 mg), 4 weeks apart. The mean follow-up period was 23.6 ± 9.9 months (range, 8-36 months). During this period, no recurrence occurred with control of the associated systemic disease. There was a statistically significant improvement of the visual acuity from 0.49 ± 0.36 to 0.69 ± 0.21 (P < 0.05). Among patients with unilateral lesion, three developed contralateral affection. Adverse effects from Remicade did not occur. CONCLUSION: The TNF blocker can be used in patients with severe acute posterior multifocal placoid pigment epitheliopathy with no recurrence rate. However, it does not prevent the contralateral affection. Another prospective study with a control group and longer follow-up time is needed to confirm these results and to evaluate the effect of TNF blocker on final visual acuity.

Screening estrogenic activity of environmental contaminants and water samples using a transgenic medaka embryo bioassay.

Many natural or synthetic chemicals may act as exogenous estrogens and affect the reproductive health of humans and wildlife. Since these xenoestrogens are ubiquitous, it is essential to monitor their presence in the environment. Hence, we developed a bioassay using the transgenic medaka (Oryzias latipes) embryo, in which the green fluorescent protein (GFP) was placed under the control of the gnrh3 promoter, one of the three paralogous gonadotropin-releasing hormone (GnRH) genes that regulate reproductive function and behavior. As medaka embryos are transparent, the fluorescent expression of GFP can be easily observed in vivo during development. We exposed newly fertilized medaka embryos to varying solutions of bisphenol A (BPA), nonylphenol (NP), 17ß-estradiol (E2), or a river water sample, and monitored their development. During embryonic development, the mRNA levels of GnRHs, GnRH receptors, and estrogen receptors (ERs) were measured with quantitative real-time reverse transcription-PCR. Our results showed that the chemicals and the river water significantly decreased the fluorescent intensity of the GnRH3 neurons, postponed the eye development, and retarded the growth of the embryos. The three xenoestrogens also lowered the heart rate, lengthened the time to hatch, suppressed the expression of the three GnRH genes, and up-regulated the ERα mRNA level. In addition, the GnRH3 mRNA level was significantly correlated with the fluorescence intensity of the GnRH neurons. We concluded that the transgenic medaka embryo is a rapid and sensitive bioassay for screening environmental water samples. We also found that xenoestrogens had significant effects on GnRH gene expression and embryonic development.

Axitinib modulates hypoxia-induced blood-retina barrier permeability and expression of growth factors.

This study investigates the effects of the multikinase inhibitor axitinib on the expression of vascular endothelial growth factor (VEGF) receptors 1/2 (VEGFR-1/2) and platelet-derived growth factor (PDGF) receptor beta (PDGFR-ß), hypoxia-induced increased tissue permeability, occludin, zonula occludens protein 1 (ZO-1), VEGF-A, and PDGF expression of human retinal pigment epithelial (RPE) cells and human umbilical vein endothelial cells (HUVECs). Primary human RPE cells and HUVECs were exposed to hypoxia and axitinib. Viability of cells, tissue permeability, and expression of occludin, ZO-1, VEGF, PDGF, VEGFR-1/2 and PDGFR-ß, and their mRNAs, were investigated by reverse transcription-polymerase chain reaction, enzyme-linked immunosorbent assay, western blotting, and immunohistochemistry. Treatment with axitinib reduced expression of VEGFR-1/2 and PDGFR-ß. Hypoxia decreased cell viability, occludin, and ZO-1 expression and increased tissue permeability, expression, and secretion of VEGF and PDGF. Axitinib significantly reduced hypoxia-induced effects on HUVEC and RPE cells. Our in vitro results suggest that axitinib may have promising properties as a potential treatment for diabetic macular edema.

[Efficacy of three intravitreal injections of bevacizumab in the treatment of exudative age-related macular degeneration]. / Étude préliminaire sur l'efficacité de trois injections intravitréennes de bevacizumab dans le traitement de la dégénérescence maculaire liée à l'âge exsudative.

INTRODUCTION: To evaluate intravitreal bevacizumab therapy for choroidal neovascularization (CNV) secondary to age-related macular degeneration (AMD). MATERIAL AND METHODS: A retrospective review between June 2006 and May 2008 of patients with CNV secondary to AMD was conducted. All patients were treated with intravitreal injection of bevacizumab (1.25mg) once a month during a 3-month-period. The mean evaluation criteria were the best-corrected visual acuity (BCVA) logMar testing before and one month after the third injection. All eyes underwent an angiography and an optical coherence tomography before injections to define the activity and the type of CNV and then to evaluate the persistence of leakage (macular edema, subretinal fluid, and pigment epithelial detachment) after treatment. Then treatments were left to the investigator's discretion during the following six months. RESULTS: Seventy-one eyes of 66 patients were enrolled. There were 65% occult CNV, 20% classic CNV, and 15% combined. A significant improvement in BCVA was observed, from 0.88±0.57 to 0.77±0.60 (p=0.001), one month after the third injection. At this time, 57.7% of the eyes required a reinjection because of leakage persistence. A concomitant treatment with intravitreal triamcinolone injection and/or photodynamic therapy was necessary for 8% of nonresponder eyes. Six months after initial treatment, a complete resolution of exudative signs was not obtained for 33.8% of eyes. The average number of injections was 3.85±0.96 during the 9-month follow-up. BCVA stability was observed at 4, 6 and 9-month follow-ups (F(71.2)=1.54; p=0.46). Three complications occurred: one endophthalmitis, one retinal tear, and one vitreous hemorrhage secondary to a macular hemorrhage. DISCUSSION: Mean BCVA significantly improved at one month after three consecutive monthly intravitreal injections of bevacizumab. However, most eyes required a reinjection. CONCLUSION: In spite of improvement in BCVA, leakage of the CNV persisted in most eyes after three monthly intravitreal injections of bevacizumab. Then retreatment and sometimes concomitant treatment was necessary to obtain complete resolution of exudative signs and BCVA stability.

[The role of light in the developement of RPE degeneration in AMD and potential cytoprotection of minocycline]. / Altersbedingte Makuladegeneration: die Rolle von Licht bei der Entstehung degenerativer Veränderungen im menschlichen RPE und möglicher Zell-Schutz durch Minocyclin.

BACKGROUND: Light-induced oxidative stress is an suggested reason for retinal pigment epithelium (RPE) degeneration in age-related macular degeneration (AMD). This study investigates the influence of light on intracellular reactive oxygen species (ROS) and apoptosis in the human RPE and potential cytoprotective effects of the tetracycline antibiotic minocycline. METHODS: Primary human RPE cells were either pre- or post-incubated with minocycline and then exposed to white light or oxidative stress (600 µM, H(2)O(2)). Then viability, induction of intracellular reactive oxygen species (ROS), apoptosis and cell death was determined. Expression of apoptotic BAX and anti-apoptotic Bcl-2 protein and their mRNA were determined by RT-PCR and Western blot analysis. RESULTS: Both light exposure and oxidative stress decreased RPE cell viability and Bcl-2 expression and increased intracellular ROS, apoptotic cell death, and BAX expression. Minocycline reduced these effects under certain conditions. CONCLUSIONS: This study demonstrates that minocycline effectively protects human RPE cells against oxidative damage. However, in the light of minocycline's photosensitising properties its potential role in AMD treatment needs further evaluation.

Mitochondrial decay and impairment of antioxidant defenses in aging RPE cells.

In the eye, the retinal pigment epithelium (RPE) is exposed to a highly oxidative environment, partly due to elevated oxygen partial pressure from the choriocapillaris and to digestion of polyunsaturated fatty acid laden photoreceptor outer segments. Here we examined the vulnerability of RPE cells to stress and changes in their mitochondria with increased chronological aging and showed that there is greater sensitivity of the cells to oxidative stress, alterations in their mitochondrial number, size, shape, matrix density, cristae architecture, and membrane integrity as a function of age. These features correlate with reduced cellular levels of ATP, ROS, and [Ca(2+)](c), lower Deltapsim, increased [Ca(2+)](m) sequestration and decreased expression of mtHsp70, UCP2, and SOD3. Mitochondrial decay, bioenergetic deficiencies, and weakened antioxidant defenses in RPE cells occur as early as age 62. With increased severity, these conditions may significantly reduce RPE function in the retina and contribute to age related retinal anomalies.

Hydroxytyrosol protects against oxidative damage by simultaneous activation of mitochondrial biogenesis and phase II detoxifying enzyme systems in retinal pigment epithelial cells.

Studies in this laboratory have previously shown that hydroxytyrosol, the major antioxidant polyphenol in olives, protects ARPE-19 human retinal pigment epithelial cells from oxidative damage induced by acrolein, an environmental toxin and endogenous end product of lipid oxidation, that occurs at increased levels in age-related macular degeneration lesions. A proposed mechanism for this is that protection by hydroxytyrosol against oxidative stress is conferred by the simultaneous activation of two critically important pathways, viz., induction of phase II detoxifying enzymes and stimulation of mitochondrial biogenesis. Cultured ARPE-19 cells were pretreated with hydroxytyrosol and challenged with acrolein. The protective effects of hydroxytyrosol on key factors of mitochondrial biogenesis and phase II detoxifying enzyme systems were examined. Hydroxytyrosol treatment simultaneously protected against acrolein-induced inhibition of nuclear factor-E2-related factor 2 (Nrf2) and peroxisome proliferator-activated receptor coactivator 1 alpha (PPARGC1α) in ARPE-19 cells. The activation of Nrf2 led to activation of phase II detoxifying enzymes, including γ-glutamyl-cysteinyl-ligase, NADPH (nicotinamide adenine dinucleotide phosphate)-quinone-oxidoreductase 1, heme-oxygenase-1, superoxide dismutase, peroxiredoxin and thioredoxin as well as other antioxidant enzymes, while the activation of PPARGC1α led to increased protein expression of mitochondrial transcription factor A, uncoupling protein 2 and mitochondrial complexes. These results suggest that hydroxytyrosol is a potent inducer of phase II detoxifying enzymes and an enhancer of mitochondrial biogenesis. Dietary supplementation of hydroxytyrosol may contribute to eye health by preventing the degeneration of retinal pigment epithelial cells induced by oxidative stress.

Multifunctional antioxidants for the treatment of age-related diseases.

Analogues of N,N-dimethyl-4-(pyrimidin-2-yl)piperazine-1-sulfonamide possessing a free radical scavenger group (FRS), chelating groups (CHL), or both (FRS + CHL) have been synthesized. Electrospray ionization mass spectrometry studies indicate that select members of this series bind ions in the relative order of Cu(1+) = Cu(2+) > Fe(2+) = Fe(3+) > Zn(2+) with no binding of Ca(2+) or Mg(2+) observed. In vitro evaluation of these compounds in human lens epithelial, human retinal pigmented epithelial, and human hippocampal astrocyte cell lines indicates that all analogues possessing the FRS group as well as the water-soluble vitamin E analogue 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid protect these cells against decreased cell viability and glutathione levels induced by hydrogen peroxide. In addition, those compounds possessing CHL groups also protected these cells against hydroxyl radicals generated by the Fenton reaction. These compounds are good candidates for the preventive treatment of cataract, age-related macular degeneration (AMD), and Alzheimer's dementia (AD).