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Qiu Y, Tao L, Lei C, Wang J, Yang P, Li Q, Lei B. Downregulating p22phox ameliorates inflammatory response in Angiotensin II-induced oxidative stress by regulating MAPK and NF-κB pathways in ARPE-19 cells. Sci Rep 2015; 5:14362. [PMID: 26415877 PMCID: PMC4586461 DOI: 10.1038/srep14362] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 08/24/2015] [Indexed: 11/24/2022] Open
Abstract
Oxidative stress and inflammation are two interrelated biological events implicated in the pathogenesis of many diseases. Reactive oxygen species (ROS) produced under oxidative stress play a key role in pathological conditions. Inhibition of p22phox, an indispensable component of the NADPH oxidase (NOX) complex comprising the main source of ROS, plays a protective role in many ocular conditions by inhibiting the activation of NOXs and the generation of ROS. However, little is understood regarding the role of p22phox in oxidative stress-related inflammation in the eye. We used a p22phox small interfering RNA (siRNA) to transfect the retinal pigment epithelium (RPE)-derived cell line ARPE-19, and human primary RPE (hRPE) cells, then stimulated with Ang II. We observed a potent anti-inflammatory effect and studied the underlying mechanism. Downregulating p22phox resulted in decreased ROS generation, a reduction of NOXs (NOX1, 2, 4) and a decrease in inflammatory cytokine. In addition, p22phox downregulation reduced the activation of the MAPK and NF-κB signaling pathways. We conclude that inhibition of p22phox has an anti-inflammatory effect in Ang II-induced oxidative stress. Suppressing the MAPK and NF-κB pathways is involved in this protective effect. These results suggest that p22phox may provide a promising therapeutic target for oxidative stress-induced ocular inflammation
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Affiliation(s)
- Yiguo Qiu
- Department of Ophthalmology, the First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Ophthalmology, Chongqing Eye Institute, Chongqing, China
| | - Lifei Tao
- Department of Ophthalmology, the First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Ophthalmology, Chongqing Eye Institute, Chongqing, China
| | - Chunyan Lei
- Department of Ophthalmology, the First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Ophthalmology, Chongqing Eye Institute, Chongqing, China
| | - Jiaming Wang
- Department of Ophthalmology, the First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Ophthalmology, Chongqing Eye Institute, Chongqing, China
| | - Peizeng Yang
- Department of Ophthalmology, the First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Ophthalmology, Chongqing Eye Institute, Chongqing, China
| | - Qiuhong Li
- Department of Ophthalmology, University of Florida, Gainesville, Florida, USA
| | - Bo Lei
- Department of Ophthalmology, the First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Ophthalmology, Chongqing Eye Institute, Chongqing, China
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102
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Catalioto RM, Valenti C, Maggi CA, Giuliani S. Enhanced Ca(2+) response and stimulation of prostaglandin release by the bradykinin B2 receptor in human retinal pigment epithelial cells primed with proinflammatory cytokines. Biochem Pharmacol 2015; 97:189-202. [PMID: 26235941 DOI: 10.1016/j.bcp.2015.07.034] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 07/27/2015] [Indexed: 12/18/2022]
Abstract
Kallikrein, kininogen and kinin receptors are present in human ocular tissues including the retinal pigment epithelium (RPE), suggesting a possible role of bradykinin (BK) in physiological and/or pathological conditions. To test this hypothesis, kinin receptors expression and function was investigated for the first time in human fetal RPE cells, a model close to native RPE, in both control conditions and after treatment with proinflammatory cytokines. Results showed that BK evoked intracellular Ca(2+) transients in human RPE cells by activating the kinin B2 receptor. Pretreatment of the cells with TNF-α and/or IL-1β enhanced Ca(2+) response in a time- and concentration-dependent additive manner, whereas the potency of BK and that of the selective B2 receptor antagonist, fasitibant chloride, both in the nanomolar range, remained unaffected. Cytokines have no significant effect on cell number and viability and on the activity of other GPCRs such as the kinin B1, acetylcholine, ATP and thrombin receptors. Immunoblot analysis and immunofluorescence studies revealed that cytokines treatment was associated with an increase in both kinin B2 receptor and COX-2 expression and with the secretion of prostaglandin E1 and E2 into the extracellular medium. BK, through activation of the kinin B2 receptor, potentiated the COX-2 mediated prostaglandin release in cytokines-primed RPE cells while new protein synthesis and prostaglandin production contribute to the potentiating effect of cytokines on BK-induced Ca(2+) response. In conclusion, overall data revealed a cross-talk between the kinin B2 receptor and cytokines in human RPE in promoting inflammation, a key feature in retinal pathologies including diabetic retinopathy and macular edema.
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Affiliation(s)
- Rose-Marie Catalioto
- Pharmacology Department, Menarini Ricerche SpA, Via Rismondo 12A, 50131 Florence, Italy.
| | - Claudio Valenti
- Pharmacology Department, Menarini Ricerche SpA, Via Rismondo 12A, 50131 Florence, Italy
| | - Carlo Alberto Maggi
- Pharmacology Department, Menarini Ricerche SpA, Via Rismondo 12A, 50131 Florence, Italy
| | - Sandro Giuliani
- Pharmacology Department, Menarini Ricerche SpA, Via Rismondo 12A, 50131 Florence, Italy
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103
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Kijlstra A, Berendschot TTJM. Age-related macular degeneration: a complementopathy? Ophthalmic Res 2015; 54:64-73. [PMID: 26159686 DOI: 10.1159/000432401] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 05/16/2015] [Indexed: 11/19/2022]
Abstract
Age-related macular degeneration (AMD) is a progressive eye disease affecting many elderly individuals. It has a multifactorial pathogenesis and is associated with numerous environmental (e.g. smoking, light and nutrition) and genetic risk factors. A breakthrough in the mechanisms causing AMD is emerging; the involvement of the alternative pathway of the complement system appears to play a pivotal role. This has led to the statement that AMD is a disease caused by a hyperactive complement system, allowing the term 'complementopathy' to define it more precisely. Abundant evidence includes: the identification of drusen components as activators of complement, immunohistochemical data showing the presence of many species of the complement system in the retinal pigment epithelium-Bruch's membrane-choroidocapillary region of AMD eyes, a strong association of AMD with certain genetic complement protein variants, raised complement levels in blood from AMD patients and the preliminary successful treatments of geographic atrophy with complement factor D (FD) inhibitors. FD is the rate-limiting enzyme of the alternative complement pathway, and is produced by adipose tissue. Recent findings suggest that nutrition may play a role in controlling the level of FD in the circulation. Addressing modifiable risk factors such as smoking and nutrition may thus offer opportunities for the prevention of AMD.
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Affiliation(s)
- Aize Kijlstra
- University Eye Clinic Maastricht, Maastricht, The Netherlands
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104
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Ratnayaka JA, Serpell LC, Lotery AJ. Dementia of the eye: the role of amyloid beta in retinal degeneration. Eye (Lond) 2015; 29:1013-26. [PMID: 26088679 PMCID: PMC4541342 DOI: 10.1038/eye.2015.100] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 04/23/2015] [Indexed: 11/09/2022] Open
Abstract
Age-related macular degeneration (AMD) is one of the most common causes of irreversible blindness affecting nearly 50 million individuals globally. The disease is characterised by progressive loss of central vision, which has significant implications for quality of life concerns in an increasingly ageing population. AMD pathology manifests in the macula, a specialised region of the retina, which is responsible for central vision and perception of fine details. The underlying pathology of this complex degenerative disease is incompletely understood but includes both genetic as well as epigenetic risk factors. The recent discovery that amyloid beta (Aβ), a highly toxic and aggregate-prone family of peptides, is elevated in the ageing retina and is associated with AMD has opened up new perspectives on the aetiology of this debilitating blinding disease. Multiple studies now link Aβ with key stages of AMD progression, which is both exciting and potentially insightful, as this identifies a well-established toxic agent that aggressively targets cells in degenerative brains. Here, we review the most recent findings supporting the hypothesis that Aβ may be a key factor in AMD pathology. We describe how multiple Aβ reservoirs, now reported in the ageing eye, may target the cellular physiology of the retina as well as associated layers, and propose a mechanistic pathway of Aβ-mediated degenerative change leading to AMD.
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Affiliation(s)
- J A Ratnayaka
- Clinical and Experimental Science, Faculty of Medicine, University of Southampton, Southampton, UK
| | - L C Serpell
- School of Life Sciences (Biochemistry, Dementia Research Group), University of Sussex, Brighton, UK
| | - A J Lotery
- Clinical and Experimental Science, Faculty of Medicine, University of Southampton, Southampton, UK
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105
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Strobbe E, Cellini M, Fresina M, Campos EC. ET-1 Plasma Levels, Aqueous Flare, and Choroidal Thickness in Patients with Retinitis Pigmentosa. J Ophthalmol 2015; 2015:292615. [PMID: 26137317 PMCID: PMC4468344 DOI: 10.1155/2015/292615] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2014] [Revised: 12/09/2014] [Accepted: 12/15/2014] [Indexed: 11/17/2022] Open
Abstract
Purpose. To assess endothelin-1 (ET-1) plasma levels, choroidal thickness, and aqueous flare in patients with early stage retinitis pigmentosa (RP) and to search for possible correlations. Methods. We compared 24 RP patients with 24 healthy controls. Choroidal thickness and aqueous flare were measured, respectively, by using a spectral domain optical coherence tomography and a laser flare-cell meter, whereas plasma samples were obtained from each patient to evaluate ET-1 plasma levels. Results. Notably, RP subjects showed significantly increased ET-1 plasma levels and reduced choroidal thickness compared with controls: 2.143 ± 0.258 versus 1.219 ± 0.236 pg/mL, P < 0.002, and 226.75 ± 76.37 versus 303.9 ± 39.87 μm, P < 0.03, respectively. Higher aqueous flare values were also demonstrated in RP compared to controls: in detail, 10.51 ± 3.97 versus 5.66 ± 1.29 photon counts/ms, P < 0.0001. Spearman's correlation test highlighted that the increase of ET-1 plasma levels was related with the decrease of choroidal thickness (r = -0.702; P < 0.023) and the increase of aqueous flare (r = 0.580; P < 0.007). Conclusions. Early stage RP patients show a breakdown of blood-ocular barrier and increased ET-1 plasma levels and these findings may contribute to the reduction of choroidal thickness.
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Affiliation(s)
- Ernesto Strobbe
- Ophthalmology Unit, Department of Experimental, Diagnostic, and Specialty Medicine, Alma Mater Studiorum, University of Bologna, Via Palagi 9, 40138 Bologna, Italy
| | - Mauro Cellini
- Ophthalmology Unit, Department of Experimental, Diagnostic, and Specialty Medicine, Alma Mater Studiorum, University of Bologna, Via Palagi 9, 40138 Bologna, Italy
| | - Michela Fresina
- Ophthalmology Unit, Department of Experimental, Diagnostic, and Specialty Medicine, Alma Mater Studiorum, University of Bologna, Via Palagi 9, 40138 Bologna, Italy
| | - Emilio C. Campos
- Ophthalmology Unit, Department of Experimental, Diagnostic, and Specialty Medicine, Alma Mater Studiorum, University of Bologna, Via Palagi 9, 40138 Bologna, Italy
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106
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Faber C, Jehs T, Juel HB, Singh A, Falk MK, Sørensen TL, Nissen MH. Early and exudative age-related macular degeneration is associated with increased plasma levels of soluble TNF receptor II. Acta Ophthalmol 2015; 93:242-7. [PMID: 25363549 DOI: 10.1111/aos.12581] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 09/23/2014] [Indexed: 02/03/2023]
Abstract
PURPOSE We have recently identified homeostatic alterations in the circulating T cells of patients with age-related macular degeneration (AMD). In cultures of retinal pigment epithelial cells, we have demonstrated that T-cell-derived cytokines induced the upregulation of complement, chemokines and other proteins implicated in AMD pathogenesis. The purpose of this study was to test whether increased plasma levels of cytokines were present in patients with AMD. METHODS We conducted a case-control study. Age-related macular degeneration status was assessed using standardized multimodal imaging techniques. Plasma was isolated from freshly drawn peripheral venous blood samples and analysed for interleukin (IL)15, IL18, interferon (IFN)γ, soluble tumour necrosis factor (TNF) receptor II (sTNFRII) and complement factor H (CFH) Y402H genotype. RESULTS We included 136 individuals with early or late forms of AMD and 74 controls. Significantly increased levels of sTNFRII were observed in patients with early or exudative AMD (p < 0.01). After adjusting for CFH Y402H genotype, age, sex and smoking history, the level of sTNFRII remained a significant predictor for prevalence of AMD with odds ratios at 3.0 in the middle and 3.6 in the highest tertiles. Levels of IL15, IL18 and IFNγ were low and not associated with AMD. CONCLUSIONS Increased plasma level of sTNFRII is found to be associated with AMD. The data supports the observations of low-grade, systemic inflammatory alterations in patients with AMD. However, it remains to be determined whether increased levels of TNFα can be found, which directly reflects an increased activity of macrophages and T cells.
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Affiliation(s)
- Carsten Faber
- Department of International Health, Immunology and Microbiology Faculty of Health and Medical Sciences University of Copenhagen Copenhagen N Denmark
- Department of Ophthalmology Glostrup Hospital Glostrup Denmark
| | - Tina Jehs
- Department of International Health, Immunology and Microbiology Faculty of Health and Medical Sciences University of Copenhagen Copenhagen N Denmark
| | - Helene Bæk Juel
- Department of International Health, Immunology and Microbiology Faculty of Health and Medical Sciences University of Copenhagen Copenhagen N Denmark
| | - Amardeep Singh
- Department of Ophthalmology Copenhagen University Hospital Roskilde Roskilde Denmark
- Faculty of Health Sciences University of Copenhagen Copenhagen Denmark
| | - Mads Krüger Falk
- Department of Ophthalmology Glostrup Hospital Glostrup Denmark
- Department of Ophthalmology Copenhagen University Hospital Roskilde Roskilde Denmark
- Faculty of Health Sciences University of Copenhagen Copenhagen Denmark
| | - Torben Lykke Sørensen
- Department of Ophthalmology Copenhagen University Hospital Roskilde Roskilde Denmark
- Faculty of Health Sciences University of Copenhagen Copenhagen Denmark
| | - Mogens Holst Nissen
- Department of International Health, Immunology and Microbiology Faculty of Health and Medical Sciences University of Copenhagen Copenhagen N Denmark
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107
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Relvas LJM, Makhoul M, Dewispelaere R, Caspers L, Communi D, Boeynaems JM, Robaye B, Bruyns C, Willermain F. P2Y2R deficiency attenuates experimental autoimmune uveitis development. PLoS One 2015; 10:e0116518. [PMID: 25692550 PMCID: PMC4334221 DOI: 10.1371/journal.pone.0116518] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 12/10/2014] [Indexed: 12/20/2022] Open
Abstract
We aimed to study the role of the nucleotide receptor P2Y2R in the development of experimental autoimmune uveitis (EAU). EAU was induced in P2Y2+/+ and P2Y2-/- mice by immunization with IRBP peptide or by adoptive transfer of in vitro restimulated semi-purified IRBP-specific enriched T lymphocytes from spleens and lymph nodes isolated from native C57Bl/6 or P2Y2+/+ and P2Y2-/- immunized mice. Clinical and histological scores were used to grade disease severity. Splenocytes and lymph node cell phenotypes were analyzed using flow cytometry. Semi-purified lymphocytes and MACS-purified CD4+ T lymphocytes from P2Y2+/+ and P2Y2-/- immunized mice were tested for proliferation and cytokine secretion. Our data show that clinical and histological scores were significantly decreased in IRBP-immunized P2Y2-/- mice as in P2Y2-/- mice adoptively transfered with enriched T lymphocytes from C57Bl/6 IRBP-immunized mice. In parallel, naïve C57Bl/6 mice adoptively transferred with T lymphocytes from P2Y2-/- IRBP-immunized mice also showed significantly less disease. No differences in term of spleen and lymph node cell recruitment or phenotype appeared between P2Y2-/- and P2Y2+/+ immunized mice. However, once restimulated in vitro with IRBP, P2Y2-/- T cells proliferate less and secrete less cytokines than the P2Y2+/+ one. We further found that antigen-presenting cells of P2Y2-/- immunized mice were responsible for this proliferation defect. Together our data show that P2Y2-/- mice are less susceptible to mount an autoimmune response against IRBP. Those results are in accordance with the danger model, which makes a link between autoreactive lymphocyte activation, cell migration and the release of danger signals such as extracellular nucleotides.
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Affiliation(s)
- Lia Judice M. Relvas
- Dpt of Ophthalmology, CHU St-Pierre and Brugmann, Brussels, Belgium
- The Institute of Interdisciplinary Research, IRIBHM, Brussels, Belgium
- Université Libre de Bruxelles, Brussels, Belgium
- * E-mail:
| | - Maya Makhoul
- The Institute of Interdisciplinary Research, IRIBHM, Brussels, Belgium
- Université Libre de Bruxelles, Brussels, Belgium
| | - Remi Dewispelaere
- Dpt of Ophthalmology, CHU St-Pierre and Brugmann, Brussels, Belgium
- The Institute of Interdisciplinary Research, IRIBHM, Brussels, Belgium
- Université Libre de Bruxelles, Brussels, Belgium
| | - Laure Caspers
- Dpt of Ophthalmology, CHU St-Pierre and Brugmann, Brussels, Belgium
- Université Libre de Bruxelles, Brussels, Belgium
| | - Didier Communi
- The Institute of Interdisciplinary Research, IRIBHM, Brussels, Belgium
- Université Libre de Bruxelles, Brussels, Belgium
| | - Jean-Marie Boeynaems
- The Institute of Interdisciplinary Research, IRIBHM, Brussels, Belgium
- Dpt of Laboratory Medicine, Erasme Hospital, Brussels, Belgium
- Université Libre de Bruxelles, Brussels, Belgium
| | - Bernard Robaye
- The Institute of Interdisciplinary Research, IRIBHM, Gosselies, Belgium
- Université Libre de Bruxelles, Brussels, Belgium
| | - Catherine Bruyns
- The Institute of Interdisciplinary Research, IRIBHM, Brussels, Belgium
- Université Libre de Bruxelles, Brussels, Belgium
| | - François Willermain
- Dpt of Ophthalmology, CHU St-Pierre and Brugmann, Brussels, Belgium
- The Institute of Interdisciplinary Research, IRIBHM, Brussels, Belgium
- Université Libre de Bruxelles, Brussels, Belgium
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108
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Korthagen NM, van Bilsen K, Swagemakers SMA, van de Peppel J, Bastiaans J, van der Spek PJ, van Hagen PM, Dik WA. Retinal pigment epithelial cells display specific transcriptional responses upon TNF-α stimulation. Br J Ophthalmol 2015; 99:700-4. [PMID: 25680620 DOI: 10.1136/bjophthalmol-2014-306309] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2014] [Accepted: 01/26/2015] [Indexed: 12/11/2022]
Abstract
BACKGROUND/AIMS Tumour necrosis factor-α (TNF-α) is a key mediator of ocular inflammation and its interaction with the retinal pigment epithelium (RPE) may be a driving force in vitreoretinal disorders such as age-related macular degeneration, proliferative vitreoretinopathy (PVR) and diabetic retinopathy. Under inflammatory conditions, the ability of RPE cells to maintain the blood-retinal barrier and immune privilege may be lost and proliferation of RPE cells is facilitated. To gain insight into the effects of TNF-α on RPE cells, a gene expression study was performed. METHODS ARPE-19 and HT-29 cells were stimulated with 50 ng/mL TNF-α for 6 h. Gene expression patterns were compared between stimulated and control cells using whole genome gene expression arrays. Data were analysed using Partek and OmniViz and validated using quantitative RT-PCR. Functional annotation analysis was performed using Ingenuity and DAVID. RESULTS A total of 97 genes were uniquely modulated by TNF-α in ARPE-19 cells compared with HT-29 cells (86 upregulated and 11 downregulated). Most commonly affected biological processes were apoptosis, cell motility and cell signalling. The highest upregulated gene was EFNA1. Among the downregulated genes were transcription factors implicated in ocular development (SIX3, PAX6) and modulation of p53-mediated apoptosis (CITED2). CONCLUSIONS This study provides insight into the unique responses of RPE cells to TNF-α stimulation and suggests a role for genes involved in apoptosis and retinal epithelial development. These findings contribute to our understanding of the behaviour of RPE cells under inflammatory conditions and the crucial role of RPE cells in vitreoretinal diseases.
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Affiliation(s)
- Nicoline M Korthagen
- Department of Immunology, Laboratory Medical Immunology, Erasmus MC, University Medical Center Rotterdam, The Netherlands
| | - Kiki van Bilsen
- Department of Internal Medicine, Section Clinical Immunology, Erasmus MC, University Medical Center Rotterdam, The Netherlands
| | - Sigrid M A Swagemakers
- Department of Bioinformatics, Erasmus MC, University Medical Center Rotterdam, The Netherlands
| | - Jeroen van de Peppel
- Department of Internal Medicine, Section Clinical Immunology, Erasmus MC, University Medical Center Rotterdam, The Netherlands
| | - Jeroen Bastiaans
- Department of Immunology, Laboratory Medical Immunology, Erasmus MC, University Medical Center Rotterdam, The Netherlands
| | - Peter J van der Spek
- Department of Bioinformatics, Erasmus MC, University Medical Center Rotterdam, The Netherlands
| | - P Martin van Hagen
- Department of Immunology, Laboratory Medical Immunology, Erasmus MC, University Medical Center Rotterdam, The Netherlands Department of Internal Medicine, Section Clinical Immunology, Erasmus MC, University Medical Center Rotterdam, The Netherlands
| | - Willem A Dik
- Department of Immunology, Laboratory Medical Immunology, Erasmus MC, University Medical Center Rotterdam, The Netherlands
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109
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Wang H, Liao S, Geng R, Zheng Y, Liao R, Yan F, Thrimawithana T, Little PJ, Feng ZP, Lazarovici P, Zheng W. IGF-1 signaling via the PI3K/Akt pathway confers neuroprotection in human retinal pigment epithelial cells exposed to sodium nitroprusside insult. J Mol Neurosci 2014; 55:931-40. [PMID: 25339505 DOI: 10.1007/s12031-014-0448-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 10/13/2014] [Indexed: 02/01/2023]
Abstract
The pathological increase in the levels of the second messenger nitric oxide (NO) in the vitreous cavity and retina leads to injury and cell death of the retinal pigment epithelium (RPE) cells and eventually may contribute to the occurrence and development of diabetic retinopathy. In this study, we developed a cellular model of retinopathy using D407 cells (a human RPE cell line) exposed to sodium nitroprusside (SNP) and investigated the protective effect of the insulin-like growth factor-1 (IGF-1) towards this insult. Cell death and apoptosis were examined by the methyl thiazolyl tetrazolium assay and Hoechst staining, respectively. Specific inhibitors were used and phosphorylation of relevant signaling proteins was determined by Western blotting. SNP, in a concentration-dependent fashion, increased the production of reactive oxygen species (ROS) and lipid peroxidation process causing cell death by apoptosis of D407 cells. IGF-1, in a time- and dose-dependent manner, conferred protection towards SNP-mediated insult. Both phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt) and mitogen-activated protein kinase (MAPK) were activated by IGF-1 in relation to the protective effect. Blockade of the PI3K/Akt pathway abolished the protective effect of IGF-1 whereas inhibition of the MAPK pathway was ineffective. SNP decreased the phosphorylation of Akt in the cells while IGF-1 reversed this inhibitory effect. These results indicate that the protective effect of IGF-1 on D407 exposed to SNP insult is mediated by the PI3K/Akt pathway. This proposal may be exploited in the clinic to improve the viability of insulted retinal cells for maintaining physiological vision.
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Affiliation(s)
- Haitao Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, China
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The role of glial cells and the complement system in retinal diseases and Alzheimer’s disease: common neural degeneration mechanisms. Exp Brain Res 2014; 232:3363-77. [DOI: 10.1007/s00221-014-4078-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Accepted: 08/19/2014] [Indexed: 02/07/2023]
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111
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Mai K, Chui JJ, Di Girolamo N, McCluskey PJ, Wakefield D. Role of toll-like receptors in human iris pigment epithelial cells and their response to pathogen-associated molecular patterns. JOURNAL OF INFLAMMATION-LONDON 2014; 11:20. [PMID: 25089120 PMCID: PMC4118659 DOI: 10.1186/1476-9255-11-20] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Accepted: 07/05/2014] [Indexed: 01/03/2023]
Abstract
Background Toll-like receptor (TLR) activation is hypothesized to contribute to inflammatory eye disease including uveitis, yet the distribution pattern of TLRs in human uveal tissues remains poorly described. The purpose of this study was to investigate the expression profile of TLRs in human iris pigment epithelial cells (IPE) at the gene and protein level and examine the effect of pathogen-associated molecular patterns (PAMPs), such as Pam3CSK4.3HCl, Poly(I:C), lipopolysaccharides (LPS from E. coli serotype O111:B4), Flagellin, MALP-2 (macrophage activating lipopeptide-2), Poly(U) and CpGODN2395 on the production of inflammatory mediators including interleukin-8 (IL-8) and monocyte chemotactic protein 1 (MCP-1) from human IPE and retinal pigment epithelial cells (RPE). Methods RT-PCR and Western blotting was employed to investigate the expression of TLRs 1–10 in primary IPE and RPE. Secretion of IL-8 or MCP-1 following treatment with PAMPs was measured by ELISA. The role of TLR2, TLR3 and TLR4 in mediating an inflammatory response was investigated using pharmacological TLR inhibitors. Results IPE and RPE expressed transcripts for TLR1-6 and 8–10; and proteins for TLR1-6 and 9. IPE secreted IL-8 or MCP-1 in response to Pam3CSK4.3HCl, Poly(I:C), LPS and MALP-2, whereas RPE produced IL-8 only after Poly(I:C), LPS or MALP-2 treatment. TLR inhibitors (OxPAPC, CI-095 and chloroquine) blocked IL-8 secretion in Poly(I:C), LPS or MALP-2-treated IPE and RPE. Conclusions Ocular pigment epithelial cells respond to PAMPs through activation of TLRs, particularly TLR2, TLR3 and TLR4. Expression of TLRs in human IPE cells provides a basis for responses to many ocular pathogens and their activation may be involved in the pathogenesis of ocular inflammation.
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Affiliation(s)
- Kelly Mai
- Inflammation and Infection Research Centre, Department of Pathology, School of Medical Sciences, Faculty of Medicine, University of New South Wales, Sydney, Australia
| | - Jeanie Jy Chui
- Inflammation and Infection Research Centre, Department of Pathology, School of Medical Sciences, Faculty of Medicine, University of New South Wales, Sydney, Australia ; Department of Ophthalmology, Prince of Wales Hospital, Randwick, NSW, Australia
| | - Nick Di Girolamo
- Inflammation and Infection Research Centre, Department of Pathology, School of Medical Sciences, Faculty of Medicine, University of New South Wales, Sydney, Australia
| | - Peter J McCluskey
- Save Sight Institute, Sydney Eye Hospital, University of Sydney, Sydney, Australia
| | - Denis Wakefield
- Inflammation and Infection Research Centre, Department of Pathology, School of Medical Sciences, Faculty of Medicine, University of New South Wales, Sydney, Australia ; UNSW Medicine, University of New South Wales, Sydney, Australia
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112
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Silibinin inhibits ICAM-1 expression via regulation of N-linked and O-linked glycosylation in ARPE-19 cells. BIOMED RESEARCH INTERNATIONAL 2014; 2014:701395. [PMID: 25032222 PMCID: PMC4083610 DOI: 10.1155/2014/701395] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 05/07/2014] [Accepted: 05/07/2014] [Indexed: 12/03/2022]
Abstract
To evaluate the effects of silibinin on intercellular adhesion molecule-1 (ICAM-1) expression, we used ARPE-19 cells as a model in which tumor necrosis factor (TNF-α) and interferon (IFN-γ) enhanced ICAM-1 expression. This upregulation was inhibited by silibinin. In an adherence assay using ARPE-19 and THP-1 cells, silibinin inhibited the cell adhesion function of ICAM-1. The inhibitory effects of silibinin on ICAM-1 expression were mediated via the blockage of nuclear translocation of p65 proteins in TNF-α and phosphorylation of STAT1 in IFN-γ-stimulated cells. In addition, silibinin altered the degree of N-linked glycosylation posttranslationally in ARPE-19 cells by significantly enhancing MGAT3 gene expression. Silibinin can increase the O-GlcNAc levels of glycoproteins in ARPE-19 cells. In a reporter gene assay, PUGNAc, which can also increase O-GlcNAc levels, inhibited NF-κB reporter activity in TNF-α-induced ARPE-19 cells and this process was augmented by silibinin treatment. Overexpression of OGT gene was associated with reduced TNF-α-induced ICAM-1 levels, which is consistent with that induced by silibinin treatment. Taken together, silibinin inhibits ICAM-1 expression and its function through altered O-linked glycosylation in NF-κB and STAT1 signaling pathways and decreases the N-linked glycosylation of ICAM-1 transmembrane protein in proinflammatory cytokine-stimulated ARPE-19 cells.
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113
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Yang Y, Takeda A, Yoshimura T, Oshima Y, Sonoda KH, Ishibashi T. IL-10 is significantly involved in HSP70-regulation of experimental subretinal fibrosis. PLoS One 2013; 8:e80288. [PMID: 24376495 PMCID: PMC3869650 DOI: 10.1371/journal.pone.0080288] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2012] [Accepted: 10/11/2013] [Indexed: 01/22/2023] Open
Abstract
Subretinal fibrosis is directly related to severe visual loss, especially if occurs in the macula, and is frequently observed in advanced age-related macular degeneration and other refractory eye disorders such as diabetic retinopathy and uveitis. In this study, we analyzed the immunosuppressive mechanism of subretinal fibrosis using the novel animal model recently demonstrated. Both TLR2 and TLR4 deficient mice showed significant enlargement of subretinal fibrotic area as compared with wild-type mice. A single intraocular administration of heat shock protein 70 (HSP70), which is an endogenous ligand for TLR2 and TLR4, inhibited subretinal fibrosis in wild-type mice but not in TLR2 and TLR4-deficient mice. Additionally, HSP70 induced IL-10 production in eyes from wild-type mice but was impaired in both TLR2- and TLR4-deficient mice, indicating that HSP70-TLR2/TLR4 axis plays an immunomodulatory role in subretinal fibrosis. Thus, these results suggest that HSP70-TLR2/TLR4 axis is a new therapeutic target for subretinal fibrosis due to prognostic CNV.
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Affiliation(s)
- Yang Yang
- Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu university, Fukuoka, Japan
| | - Atsunobu Takeda
- Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu university, Fukuoka, Japan
| | - Takeru Yoshimura
- Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu university, Fukuoka, Japan
| | - Yuji Oshima
- Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu university, Fukuoka, Japan
| | - Koh-Hei Sonoda
- Department of Ophthalmology, Yamaguchi University School of Medicine, Ube, Yamaguchi, Japan
| | - Tatsuro Ishibashi
- Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu university, Fukuoka, Japan
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Pathogenic role of diabetes-induced PPAR-α down-regulation in microvascular dysfunction. Proc Natl Acad Sci U S A 2013; 110:15401-6. [PMID: 24003152 DOI: 10.1073/pnas.1307211110] [Citation(s) in RCA: 112] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Two independent clinical studies have reported that fenofibrate, a peroxisome proliferator-activated receptor α (PPARα) agonist, has robust therapeutic effects on microvascular complications of diabetes, including diabetic retinopathy (DR) in type 2 diabetic patients. However, the expression and function of PPARα in the retina are unclear. Here, we demonstrated that PPARα is expressed in multiple cell types in the retina. In both type 1 and type 2 diabetes models, expression of PPARα, but not PPARβ/δ or PPARγ, was significantly down-regulated in the retina. Furthermore, high-glucose medium was sufficient to down-regulate PPARα expression in cultured retinal cells. To further investigate the role of PPARα in DR, diabetes was induced in PPARα knockout (KO) mice and wild-type (WT) mice. Diabetic PPARα KO mice developed more severe DR, as shown by retinal vascular leakage, leukostasis, pericyte loss, capillary degeneration, and over-expression of inflammatory factors, compared with diabetic WT mice. In addition, overexpression of PPARα in the retina of diabetic rats significantly alleviated diabetes-induced retinal vascular leakage and retinal inflammation. Furthermore, PPARα overexpression inhibited endothelial cell migration and proliferation. These findings revealed that diabetes-induced down-regulation of PPARα plays an important role in DR. Up-regulation or activation of PPARα may represent a novel therapeutic strategy for DR.
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115
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Diniz B, Thomas P, Thomas B, Ribeiro R, Hu Y, Brant R, Ahuja A, Zhu D, Liu L, Koss M, Maia M, Chader G, Hinton DR, Humayun MS. Subretinal implantation of retinal pigment epithelial cells derived from human embryonic stem cells: improved survival when implanted as a monolayer. Invest Ophthalmol Vis Sci 2013; 54:5087-96. [PMID: 23833067 DOI: 10.1167/iovs.12-11239] [Citation(s) in RCA: 167] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
PURPOSE To evaluate cell survival and tumorigenicity of human embryonic stem cell-derived retinal pigment epithelium (hESC-RPE) transplantation in immunocompromised nude rats. Cells were transplanted as a cell suspension (CS) or as a polarized monolayer plated on a parylene membrane (PM). METHODS Sixty-nine rats (38 male, 31 female) were surgically implanted with CS (n = 33) or PM (n = 36). Cohort subsets were killed at 1, 6, and 12 months after surgery. Both ocular tissues and systemic organs (brain, liver, kidneys, spleen, heart, and lungs) were fixed in 4% paraformaldehyde, embedded in paraffin, and sectioned. Every fifth section was stained with hematoxylin and eosin and analyzed histologically. Adjacent sections were processed for immunohistochemical analysis (as needed) using the following antibodies: anti-RPE65 (RPE-specific marker), anti-TRA-1-85 (human cell marker), anti-Ki67 (proliferation marker), anti-CD68 (macrophage), and anti-cytokeratin (epithelial marker). RESULTS The implanted cells were immunopositive for the RPE65 and TRA-1-85. Cell survival (P = 0.006) and the presence of a monolayer (P < 0.001) of hESC-RPE were significantly higher in eyes that received the PM. Gross morphological and histological analysis of the eye and the systemic organs after the surgery revealed no evidence of tumor or ectopic tissue formation in either group. CONCLUSIONS hESC-RPE can survive for at least 12 months in an immunocompromised animal model. Polarized monolayers of hESC-RPE show improved survival compared to cell suspensions. The lack of teratoma or any ectopic tissue formation in the implanted rats bodes well for similar results with respect to safety in human subjects.
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Affiliation(s)
- Bruno Diniz
- Doheny Eye Institute, Los Angeles, California, USA.
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A2E induces IL-1ß production in retinal pigment epithelial cells via the NLRP3 inflammasome. PLoS One 2013; 8:e67263. [PMID: 23840644 PMCID: PMC3696103 DOI: 10.1371/journal.pone.0067263] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2012] [Accepted: 05/20/2013] [Indexed: 11/19/2022] Open
Abstract
AIMS With ageing extracellular material is deposited in Bruch's membrane, as drusen. Lipofuscin is deposited in retinal pigment epithelial cells. Both of these changes are associated with age related macular degeneration, a disease now believed to involve chronic inflammation at the retinal-choroidal interface. We hypothesise that these molecules may act as danger signals, causing the production of inflammatory chemokines and cytokines by the retinal pigment epithelium, via activation of pattern recognition receptors. METHODS ARPE-19 cells were stimulated in vitro with the following reported components of drusen: amyloid-ß (1-42), Carboxyethylpyrrole (CEP) modified proteins (CEP-HSA), Nε-(Carboxymethyl)lysine (CML) modified proteins and aggregated vitronectin. The cells were also stimulated with the major fluorophore of lipofuscin: N-retinylidene-N-retinylethanolamine (A2E). Inflammatory chemokine and cytokine production was assessed using Multiplex assays and ELISA. The mechanistic evaluation of the NLRP3 inflammasome pathway was assessed in a stepwise fashion. RESULTS Of all the molecules tested only A2E induced inflammatory chemokine and cytokine production. 25 µM A2E induced the production of significantly increased levels of the chemokines IL-8, MCP-1, MCG and MIP-1α, the cytokines IL-1ß, IL-2, IL-6, and TNF-α, and the protein VEGF-A. The release of IL-1ß was studied further, and was determined to be due to NLRP3 inflammasome activation. The pathway of activation involved endocytosis of A2E, and the three inflammasome components NLRP3, ASC and activated caspase-1. Immunohistochemical staining of ABCA4 knockout mice, which show progressive accumulation of A2E levels with age, showed increased amounts of IL-1ß proximal to the retinal pigment epithelium. CONCLUSIONS A2E has the ability to stimulate inflammatory chemokine and cytokine production by RPE cells. The pattern recognition receptor NLRP3 is involved in this process. This provides further evidence for the link between A2E, inflammation, and the pathogenesis of AMD. It also supports the recent discovery of NLRP3 inflammasome activation in AMD.
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A Novel Platelet-Activating Factor Receptor Antagonist Inhibits Choroidal Neovascularization and Subretinal Fibrosis. PLoS One 2013; 8:e68173. [PMID: 23826375 PMCID: PMC3694891 DOI: 10.1371/journal.pone.0068173] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2012] [Accepted: 05/28/2013] [Indexed: 11/19/2022] Open
Abstract
Choroidal neovascularization (CNV) is a critical pathogenesis in age-related macular degeneration (AMD), the most common cause of blindness in developed countries. To date, the precise molecular and cellular mechanisms underlying CNV have not been elucidated. Platelet-activating factor (PAF) has been previously implicated in angiogenesis; however, the roles of PAF and its receptor (PAF-R) in CNV have not been addressed. The present study reveals several important findings concerning the relationship of the PAF-R signaling with CNV. PAF-R was detected in a mouse model of laser-induced CNV and was upregulated during CNV development. Experimental CNV was suppressed by administering WEB2086, a novel PAF-R antagonist. WEB2086-dependent suppression of CNV occurred via the inhibition of macrophage infiltration and the expression of proangiogenic (vascular endothelial growth factor) and proinflammatory molecules (monocyte chemotactic protein-1 and IL-6) in the retinal pigment epithelium-choroid complex. Additionally, WEB2086-induced PAF-R blockage suppresses experimentally induced subretinal fibrosis, which resembles the fibrotic subretinal scarring observed in neovascular AMD. As optimal treatment modalities for neovascular AMD would target the multiple mechanisms of AMD-associated vision loss, including neovascularization, inflammation and fibrosis, our results suggest PAF-R as an attractive molecular target in the treatment of AMD.
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Parainflammation associated with advanced glycation endproduct stimulation of RPE in vitro: implications for age-related degenerative diseases of the eye. Cytokine 2013; 62:369-81. [PMID: 23601964 DOI: 10.1016/j.cyto.2013.03.027] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 03/14/2013] [Accepted: 03/26/2013] [Indexed: 12/22/2022]
Abstract
Age related macular degeneration (AMD) is one of the leading causes of blindness in Western society. A hallmark of early stage AMD are drusen, extracellular deposits that accumulate in the outer retina. Advanced glycation endproducts (AGE) accumulate with aging and are linked to several age-related diseases such as Alzheimer's disease, osteoarthritis, atherosclerosis and AMD. AGE deposits are found in drusen and in Bruch's membrane of the eye and several studies have suggested its role in promoting oxidative stress, apoptosis and lipofuscin accumulation. Recently, complement activation and chronic inflammation have been implicated in the pathogenesis of AMD. While AGEs have been shown to promote inflammation in other diseases, whether it plays a similar role in AMD is not known. This study investigates the effects of AGE stimulation on pro- and anti-inflammatory pathways in primary culture of human retinal pigment epithelial cells (RPE). Differential gene expression studies revealed a total of 41 up- and 18 down-regulated RPE genes in response to AGE stimulation. These genes fell into three categories as assessed by gene set enrichment analysis (GSEA). The main categories were inflammation (interferon-induced, immune response) and proteasome degradation, followed by caspase signaling. Using suspension array technology, protein levels of secreted cytokines and growth factors were also examined. Anti-inflammatory cytokines including IL10, IL1ra and IL9 were all overexpressed. Pro-inflammatory cytokines including IL4, IL15 and IFN-γ were overexpressed, while other pro-inflammatory cytokines including IL8, MCP1, IP10 were underexpressed after AGE stimulation, suggesting a para-inflammation state of the RPE under these conditions. Levels of mRNA of chemokine, CXCL11, and viperin, RSAD2, were up-regulated and may play a role in driving the inflammatory response via the NF-kB and JAK-STAT pathways. CXCL11 was strongly immunoreactive and associated with drusen in the AMD eye. The pathways and novel genes identified here highlight inflammation as a key response to AGE stimulation in primary culture of human RPE, and identify chemokine CXCL11 as putative novel agent associated with the pathogenesis of AMD.
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119
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Liu RT, Gao J, Cao S, Sandhu N, Cui JZ, Chou CL, Fang E, Matsubara JA. Inflammatory mediators induced by amyloid-beta in the retina and RPE in vivo: implications for inflammasome activation in age-related macular degeneration. Invest Ophthalmol Vis Sci 2013; 54:2225-37. [PMID: 23462752 DOI: 10.1167/iovs.12-10849] [Citation(s) in RCA: 112] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
PURPOSE Drusen are hallmarks of age-related macular degeneration (AMD). Amyloid-beta 1-40 (Aβ 1-40), a constituent of drusen, is known to stimulate inflammatory pathways in RPE; however, its effect in vivo is not known. The purpose of this study was to examine the effect of Aβ 1-40 on cytokine expression and inflammasome activation relevant to AMD in an animal model. METHODS Wild-type rats received intravitreal injections of Aβ 1-40, and eyes were taken at days 1, 4, 14, and 49 postinjection. The RPE, neuroretina, and vitreous were analyzed for cytokine expression, inflammasome activation, and microglial response via RT-PCR, immunohistochemistry, and suspension array assay. Retinal cell loss was assessed via apoptotic markers and retinal thickness. RESULTS Aβ 1-40 stimulated upregulation of IL-6, TNF-α, IL-1β, IL-18, caspase-1, NLRP3, and XAF1 genes in the RPE/choroid and the neuroretina. Increased IL-1β and IL-6 immunoreactivity was found in retinal sections, and elevated levels of IL-1β and IL-18 were found in the vitreous of Aβ-injected eyes. Aβ 1-40 induced a moderate increase in CD11b/c-reactive cells on day 1 postinjection only. No evidence of the proapoptotic XAF1 protein, p53, TUNEL immunoreactivity, or retinal thinning was observed. CONCLUSIONS These results confirm earlier in vitro work and support the proinflammatory role of drusen component Aβ 1-40 in the RPE and retina. Inflammasome activation may be responsible for this effect in vivo. This model is useful for understanding cellular triggers of inflammasome activation and proposed early inflammatory events in the outer retina associated with the etiology of AMD.
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Affiliation(s)
- Ruozhou Tom Liu
- Department of Ophthalmology and Visual Sciences, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
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Kaczara P, Zaręba M, Herrnreiter A, Skumatz CMB, Ządło A, Sarna T, Burke JM. Melanosome-iron interactions within retinal pigment epithelium-derived cells. Pigment Cell Melanoma Res 2012; 25:804-14. [PMID: 22883111 DOI: 10.1111/pcmr.12008] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Revised: 08/07/2012] [Indexed: 01/28/2023]
Abstract
Melanosomes were recently shown to protect ARPE-19 cells, a human retinal pigment epithelium (RPE) cell line, against oxidative stress induced by hydrogen peroxide. One postulated mechanism of antioxidant action of melanin is its ability to bind metal ions. The aim here was to determine whether melanosomes are competent to bind iron within living cells, exhibiting a property previously shown only in model systems. The outcomes indicate retention of prebound iron and accumulation of iron by granules after iron delivery to cells via the culture medium, as determined by both colorimetric and electron spin resonance analyses for bound-to-melanosome iron. Manipulation of iron content did not affect the pigment's ability to protect cells against H(2) O(2) , but the function of pigment granules within RPE cells should be extended beyond a role in light irradiation to include participation in iron homeostasis.
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Affiliation(s)
- Patrycja Kaczara
- Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387, Krakow, Poland
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Rutar M, Natoli R, Provis JM. Small interfering RNA-mediated suppression of Ccl2 in Müller cells attenuates microglial recruitment and photoreceptor death following retinal degeneration. J Neuroinflammation 2012; 9:221. [PMID: 22992301 PMCID: PMC3546872 DOI: 10.1186/1742-2094-9-221] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2012] [Accepted: 09/06/2012] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND The recruitment and activation of inflammatory cells is thought to exacerbate photoreceptor death in retinal degenerative conditions such as age-related macular degeneration (AMD). We investigated the role of Müller cell-derived chemokine (C-C motif) ligand (Ccl)2 expression on monocyte/microglia infiltration and photoreceptor death in light-mediated retinal degeneration, using targeted small interfering (si)RNA. METHODS Adult Sprague-Dawley rats were injected intravitreally with 1 μg of either Ccl2 siRNA or scrambled siRNA, and were then exposed to 1000 lux of light for a period of 24 hours. The mice were given an overdose of barbiturate, and the retinas harvested and evaluated for the effects of bright-light exposure. Ccl2 expression was assessed by quantitative PCR, immunohistochemistry, and in situ hybridization. Monocytes/microglia were counted on retinal cryostat sections immunolabeled with the markers ED1 and ionized calcium binding adaptor (IBA)1, and photoreceptor apoptosis was assessed using terminal dUTP nick end labeling. RESULTS Intravitreal injection of Ccl2 siRNA significantly reduced the expression of Ccl2 following light damage to 29% compared with controls. In retinas injected with Ccl2 siRNA, in situ hybridization and immunohistochemistry on retinal cryostat sections showed a substantial decrease in Ccl2 within Müller cells. Cell counts showed significantly fewer ED1-positive and IBA1-positive cells in the retinal vasculature and outer nuclear layer of Ccl2 siRNA-injected retinas, compared with controls. Moreover, there was significantly less photoreceptor apoptosis in Ccl2 siRNA-injected retinas compared with controls. CONCLUSIONS Our data indicate that Ccl2 expression by Müller cells promotes the infiltration of monocytes/microglia, thereby contributing to the neuroinflammatory response and photoreceptor death following retinal injury. Modulation of exaggerated chemokine responses using siRNA may have value in reducing inflammation-mediated cell death in retinal degenerative disease such as AMD.
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Affiliation(s)
- Matt Rutar
- The John Curtin School of Medical Research, College of Medicine, Biology and Environment, The Australian National University, Building 131, Garran Rd, Canberra, ACT 0200, Australia.
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Peng S, Gan G, Rao VS, Adelman RA, Rizzolo LJ. Effects of proinflammatory cytokines on the claudin-19 rich tight junctions of human retinal pigment epithelium. Invest Ophthalmol Vis Sci 2012; 53:5016-28. [PMID: 22761260 DOI: 10.1167/iovs.11-8311] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
PURPOSE Chronic, subclinical inflammation contributes to the pathogenesis of several ocular diseases, including age-related macular degeneration. Proinflammatory cytokines affect tight junctions in epithelia that lack claudin-19, but in the retinal pigment epithelium claudin-19 predominates. We examined the effects of cytokines on the tight junctions of human fetal RPE (hfRPE). METHODS hfRPE was incubated with interleukin 1-beta (IL-1β), interferon-gamma (IFNγ), or tumor necrosis factor-alpha (TNFα), alone or in combination. Permeability and selectivity of the tight junctions were assessed using nonionic tracers and electrophysiology. Claudins, occludin, and ZO-1 were examined using PCR, immunoblotting, and confocal immunofluorescence microscopy. RESULTS Only TNFα consistently reduced transepithelial electrical resistance (TER) >80%. A serum-free medium revealed two effects of TNFα: (1) decreased TER was observed only when TNFα was added to the apical side of the monolayer, and (2) expression of TNFα receptors and inhibitors of apoptosis were induced from either side of the monolayer. In untreated cultures, tight junctions were slightly cation selective, and this was affected minimally by TNFα. The results were unexplained by effects on claudin-2, claudin-3, claudin-19, occludin, and ZO-1, but changes in the morphology of the junctions and actin cytoskeleton may have a role. CONCLUSIONS Claudin-19-rich tight junctions have low permeability for ionic and nonionic solutes, and are slightly cation-selective. Claudin-19 is not a direct target of TNFα. TNFα may protect RPE from apoptosis, but makes the monolayer leaky when it is presented to the apical side of the monolayer. Unlike other epithelia, IFNγ failed to augment the effect of TNFα on tight junctions.
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Affiliation(s)
- Shaomin Peng
- Department of Surgery, Yale University School of Medicine, New Haven, Connecticut, USA
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Stewart MW. Clinical and differential utility of VEGF inhibitors in wet age-related macular degeneration: focus on aflibercept. Clin Ophthalmol 2012; 6:1175-86. [PMID: 22973088 PMCID: PMC3422153 DOI: 10.2147/opth.s33372] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Age-related macular degeneration (AMD) has become a major public health problem and a leading cause of blindness in industrialized nations. AMD results from the ageing eye's inability to metabolize and dispose completely of photoreceptor outer segments and other waste products. As a result, lipids, particularly apolipoproteins, accumulate within Bruch's membrane, leading to chronic ischemia and inflammation. The subsequent upregulation of inflammatory cytokines and growth factors, including vascular endothelial growth factor (VEGF), induces the growth of neovascular membranes from the choriocapillaris into the subretinal or subretinal pigment epithelium spaces. To counter this, intravitreally administered drugs (pegaptanib, bevacizumab, ranibizumab) that specifically target VEGF have become the standard treatment for exudative AMD. Aflibercept, a recently approved fusion protein, binds to all isoforms of both VEGF-A and placental growth factor with high affinity. Phase III trials showed that monthly or every other month injections of aflibercept prevent vision loss (fewer than 15 letters) in 95% of patients. Additionally, aflibercept injections every 4 or 8 weeks produce average vision gains of 6.9 letters to 10.9 letters, comparable with those achieved with monthly ranibizumab. After one year of regularly administered aflibercept injections, patients required an average of only 4.2 injections during the second year. Aflibercept promises to decrease the injection frequency required for many patients and appears to serve as an effective "salvage" therapy for patients who respond poorly to other anti-VEGF drugs.
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Spectral domain optical coherence tomography of Vogt-Koyanagi-Harada disease: novel findings and new insights into the pathogenesis. ACTA ACUST UNITED AC 2012; 27:29-34. [PMID: 22734211 DOI: 10.1016/s1001-9294(12)60019-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
OBJECTIVE To provide novel spectral domain optical coherence tomography (SD OCT) findings of Vogt-Koyanagi-Harada (VKH) disease as well as new insights into the pathogenesis of this disease. METHODS Detailed SD OCT and fluorescein angiography (FA) findings of 18 consecutive VKH patients (11 women and 7 men) from December 2007 to April 2009 who were in acute uveitic stage at presentation were reviewed. All the patients had been followed up for at least 6 months with reevaluation(s) of SD OCT performed in 10 patients. RESULTS Intraretinal cysts were found to be located in various layers of the outer retina. In addition to the photoreceptor layer, they could also be found between the outer plexiform layer and the outer nuclear layer, or spanning the external limiting membrane. On FA, intraretinal cysts could be hypofluorescent, normofluorescent, or hyperfluorescent. Some intraretinal cysts had a characteristic FA pattern, in which a small round hypofluorescent area was surrounded by a ring of hyperfluorescence (donut-shaped dye pooling). Subretinal fibrinoid deposit appeared in acute uveitic stage in two severe VKH patients and seemed to develop from subretinal exudates and evolved into typical subretinal fibrosis. Gradual transfiguration/migration and progressive proliferation/pigmentation of the subretinal fibrinoid deposit/subretinal fibrosis was observed in one patient. CONCLUSIONS Intraretinal cysts could form in various layers of the outer retina and may result from extension of choroidal inflammation. Subretinal fibrosis may develop from subretinal exudates in VKH patients and may cause substantial visual impairment.
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125
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Ultrastructure of the human retina in aging and various pathological states. Micron 2012; 43:759-81. [DOI: 10.1016/j.micron.2012.01.011] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Accepted: 01/24/2012] [Indexed: 11/22/2022]
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Kinnunen K, Petrovski G, Moe MC, Berta A, Kaarniranta K. Molecular mechanisms of retinal pigment epithelium damage and development of age-related macular degeneration. Acta Ophthalmol 2012; 90:299-309. [PMID: 22112056 DOI: 10.1111/j.1755-3768.2011.02179.x] [Citation(s) in RCA: 144] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Age-related macular degeneration (AMD) is attributed to a complex interaction of genetic and environmental factors. It is characterized by degeneration involving the retinal photoreceptors, retinal pigment epithelium (RPE) and Bruch's membrane, as well as alterations in choroidal capillaries. AMD pathogenesis is strongly associated with chronic oxidative stress and inflammation that ultimately lead to protein damage, aggregation and degeneration of RPE. Specific degenerative findings for AMD are accumulation of intracellular lysosomal lipofuscin and extracellular drusens. In this review, we discuss thoroughly RPE-derived mechanisms in AMD pathology.
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Affiliation(s)
- Kati Kinnunen
- Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland
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Tu Z, Li Y, Smith D, Doller C, Sugita S, Chan CC, Qian S, Fung J, Caspi RR, Lu L, Lin F. Myeloid suppressor cells induced by retinal pigment epithelial cells inhibit autoreactive T-cell responses that lead to experimental autoimmune uveitis. Invest Ophthalmol Vis Sci 2012; 53:959-66. [PMID: 22247470 DOI: 10.1167/iovs.11-8377] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
PURPOSE To test whether retinal pigment epithelial (RPE) cells are able to induce myeloid-derived suppressor cell (MDSC) differentiation from bone marrow (BM) progenitors. METHODS BM cells were cocultured with or without RPE cells in the presence of GM-CSF and IL-4. Numbers of resultant MDSCs were assessed by flow cytometry after 6 days of incubation. The ability of the RPE cell-induced MDSCs to inhibit T cells was evaluated by a CFSE-based T-cell proliferation assay. To explore the mechanism by which RPE cells induce MDSC differentiation, PD-L1-deficient RPE cells and blocking antibodies against TGF-β, CTLA-2α, and IL-6 were used. RPE cell-induced MDSCs were adoptively transferred into mice immunized with interphotoreceptor retinoid-binding protein in complete Freund's adjuvant to test their efficacy in suppressing autoreactive T-cell responses in experimental autoimmune uveitis (EAU). RESULTS RPE cells induced the differentiation of MDSCs. These RPE cell-induced MDSCs significantly inhibited T-cell proliferation in a dose-dependent manner. PD-L1-deficient RPE cells induced MDSC differentiation as efficiently as wild-type RPE cells, and neutralizing TGF-β or CTLA-2α did not alter the numbers of induced MDSCs. However, blocking IL-6 reduced the efficacy of RPE cell-induced MDSC differentiation. Finally, adoptive transfer of RPE cell-induced MDSCs suppressed IRBP-specific T-cell responses that led to EAU. CONCLUSIONS RPE cells induce the differentiation of MDSCs from bone marrow progenitors. Both cell surface molecules and soluble factors are important in inducing MDSC differentiation. PD-L1, TGF-β, and CTLA-2α were not measurably involved in RPE cell-induced MDSC differentiation, whereas IL-6 was important in the process. The induction of MDSCs could be another mechanism by which RPE cells control immune reactions in the retina, and RPE cell-induced MDSCs should be further investigated as a potential approach to therapy for autoimmune posterior uveitis.
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Affiliation(s)
- Zhidan Tu
- Department of Pathology, Case Western Reserve University School of Medicine, 2085 Adelbert Road, Cleveland, OH 44106, USA
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Kramer M, Hasanreisoglu M, Feldman A, Axer-Siegel R, Sonis P, Maharshak I, Monselise Y, Gurevich M, Weinberger D. Monocyte chemoattractant protein-1 in the aqueous humour of patients with age-related macular degeneration. Clin Exp Ophthalmol 2012; 40:617-25. [PMID: 22172228 DOI: 10.1111/j.1442-9071.2011.02747.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND To investigate the role of inflammation in age-related macular degeneration by measuring the levels of cytokines in the aqueous humour. METHODS Samples of aqueous humour were collected from 34 patients with age-related macular degeneration and 16 age-matched control subjects undergoing cataract surgery. Age-related macular degeneration stage was determined clinically, before surgery. Levels of cytokines were measured using Luminex X-MAP technology, and positive results were verified by Western blot. RESULTS Age-related macular degeneration was moderate in 18 patients and advanced in 16. The advanced age-related macular degeneration group was further divided into patients with active choroidal neovascularization (n = 7), disciform scar (n = 7) or central geographic atrophy (n = 2). Higher-than-normal levels of monocyte chemoattractant protein-1 in the aqueous humour were associated with advanced age-related macular degeneration (200 ± 140 pg/mL vs. 100 ± 61 pg/mL; P = 0.03), especially active choroidal neovascularization (255 ± 155 pg/mL; P = 0.02), Western blot analysis verified the monocyte chemoattractant protein-1 findings. Patients with disciform scar showed a trend of abnormally high levels of interleukin-12 (p70) (1.7 ± 2.4 pg/mL vs. 0.2 ± 1 pg/mL; P = 0.07), tumour necrosis factor-α (1.8 ± 2.4 pg/mL vs. 0.3 ± 1 pg/mL; P = 0.06) and interleukin-12 (4.7 ± 6.4 pg/mL vs. 1.2 ± 2.1 pg/mL; P = 0.08). CONCLUSION Elevated levels of inflammation-related cytokines in the aqueous humour in various stages of age-related macular degeneration may suggest a pathogenic role of inflammation. Monocyte chemoattractant protein-1 may be indicative of the angiogenic phase. Further corroborative studies are required.
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Affiliation(s)
- Michal Kramer
- Department of Ophthalmology, Laboratory of Clinical Immunology, Rabin Medical Center, Petach Tikva, Israel.
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Zhang Y, Li C, Sun X, Kuang X, Ruan X. High glucose decreases expression and activity of p-glycoprotein in cultured human retinal pigment epithelium possibly through iNOS induction. PLoS One 2012; 7:e31631. [PMID: 22363694 PMCID: PMC3281955 DOI: 10.1371/journal.pone.0031631] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Accepted: 01/14/2012] [Indexed: 11/12/2022] Open
Abstract
Inhibition of p-glycoprotein under hyperglycemic conditions has been reported in various barrier tissues including blood-brain barrier, intestine, and kidney, and has been linked to significant clinical complications. However, whether this is also true for the outer blood-retinal barrier constituted by retinal pigment epithelium, or has a role in pathogenesis of diabetic retinopathy is not yet clear. In this study, using cultured human retinal pigment epithelium cell line D407, we found that high glucose exposure induced a significant decrease in p-glycoprotein expression both at mRNA and at protein levels, accompanied by an attenuated p-glycoprotein activity determined by intracellular rhodamine 123 retention. In marked contrast, the expressions of both mRNA and protein levels of inducible nitrate oxide synthase (iNOS) increased, and were accompanied by increased extracellular nitrate/nitrite production by Griess reaction. In addition, mRNA levels of nuclear receptors revealed a decreased expression of pregnane X receptor after the exposure of high glucose. However, the subsequent alterations in production of nitrate/nitrite, functional expression of p-glycoprotein, and mRNA levels of pregnane X receptor were partially blocked when pretreated with S,S′-1,3-phenylene-bis(1,2-ethanediyl)-bis-isothiourea•2HBr (PBITU), a selective iNOS inhibitor. Moreover, the effects of PBITU were antagonized with the addition of L-arginine, a substrate for NO synthesis. Our in vitro results suggest for the first time that iNOS induction plays a novel role in decreased p-glycoprotein expression and transport function at the human outer blood-retinal barrier under hyperglycemic conditions and further support the concept of inhibiting iNOS pathway as a therapeutic strategy for diabetic retinopathy.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B
- ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics
- ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism
- Cell Line
- Cells, Cultured
- Enzyme Induction/drug effects
- Enzyme Inhibitors/pharmacology
- Gene Expression Regulation/drug effects
- Glucose/pharmacology
- Humans
- Nitric Oxide/biosynthesis
- Nitric Oxide Synthase Type II/antagonists & inhibitors
- Nitric Oxide Synthase Type II/biosynthesis
- Nitric Oxide Synthase Type II/genetics
- Pregnane X Receptor
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Steroid/genetics
- Receptors, Steroid/metabolism
- Retinal Pigment Epithelium/cytology
- Retinal Pigment Epithelium/drug effects
- Retinal Pigment Epithelium/enzymology
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Affiliation(s)
- Yuehong Zhang
- Departments of Ophthalmology, and Anesthesiology, First Municipal People's Hospital of Guangzhou, Affiliated Hospital of Guangzhou Medical College, Guangzhou, China
| | - Chunmei Li
- Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Xuerong Sun
- Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Xielan Kuang
- Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Xiangcai Ruan
- Departments of Ophthalmology, and Anesthesiology, First Municipal People's Hospital of Guangzhou, Affiliated Hospital of Guangzhou Medical College, Guangzhou, China
- * E-mail:
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Makhoul M, Bruyns C, Edimo WE, Relvas LJ, Bazewicz M, Koch P, Caspers L, Willermain F. TNFα suppresses IFNγ-induced MHC class II expression on retinal pigmented epithelial cells cultures. Acta Ophthalmol 2012; 90:e38-42. [PMID: 21957872 DOI: 10.1111/j.1755-3768.2011.02241.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE One major consequence of retinal pigment epithelium (RPE) cell activation during autoimmune uveitis is the induction of MHC II molecules expression at their surface. IFNγ is regarded as the main cytokine involved in this induction. As TNFα plays a central role in autoimmune uveitis, we investigated its effects on IFNγ-mediated MHC II induction on RPE cells. METHODS Retinal pigment epithelium cells (ARPE-19) were stimulated with IFNγ, TNFα and the anti-TNFα antibody infliximab. The expression of MHCII and ICAM-1 was analysed by flow cytometry. The activation and expression of IRF-1 and STAT-1, two proteins involved in IFNγ-signalling pathway, were analysed by WB. Class II transactivator (CIITA) expression was monitored by qRT-PCR and immunoprecipitation. RESULTS TNFα inhibits IFNγ-induced MHC II expression on ARPE cells in a dose-dependent manner. Infliximab completely reverses the inhibitory effect of TNFα. We did not observe an inhibitory effect of TNFα on the expression of ICAM-1 induced by IFNγ. Similarly, IFNγ-induced STAT1 phosphorylation and IRF1 expression were not affected by TNFα. On the contrary, we found that TNFα suppresses IFNγ-induced CIITA mRNA accumulation and protein expression. CONCLUSION TNFα inhibits IFNγ-induced MHC II expression in RPE cells. This inhibitory effect was reversed by infliximab and was not because of a global inhibition of IFNγ -mediated RPE cell activation but rather to a specific down-regulation of CIITA expression. Those findings are consistent with the role of TNFα in the resolution of inflammation and might help to elucidate the complex development of autoimmune uveitis.
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Affiliation(s)
- Maya Makhoul
- IRIBHM (Institute of Interdisciplinary Research), Université Libre De Bruxelles-Campus Erasme, Brussels, Belgium.
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131
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Towler JC, Ebrahimi B, Lane B, Davison AJ, Dargan DJ. Human cytomegalovirus transcriptome activity differs during replication in human fibroblast, epithelial and astrocyte cell lines. J Gen Virol 2012; 93:1046-1058. [PMID: 22258857 PMCID: PMC3541802 DOI: 10.1099/vir.0.038083-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Broad cell tropism contributes to the pathogenesis of human cytomegalovirus (HCMV), but the extent to which cell type influences HCMV gene expression is unclear. A bespoke HCMV DNA microarray was used to monitor the transcriptome activity of the low passage Merlin strain of HCMV at 12, 24, 48 and 72 h post-infection, during a single round of replication in human fetal foreskin fibroblast cells (HFFF-2s), human retinal pigmented epithelial cells (RPE-1s) and human astrocytoma cells (U373MGs). In order to correlate transcriptome activity with concurrent biological responses, viral cytopathic effect, growth kinetics and genomic loads were examined in the three cell types. The temporal expression pattern of viral genes was broadly similar in HFFF-2s and RPE-1s, but dramatically different in U373MGs. Of the 165 known HCMV protein-coding genes, 41 and 48 were differentially regulated in RPE-1s and U373MGs, respectively, compared with HFFF-2s, and 22 of these were differentially regulated in both RPE-1s and U373MGs. In RPE-1s, all differentially regulated genes were downregulated, but, in U373MGs, some were down- and others upregulated. Differentially regulated genes were identified among the immediate-early, early, early late and true-late viral gene classes. Grouping of downregulated genes according to function at landmark stages of the replication cycle led to the identification of potential bottleneck stages (genome replication, virion assembly, and virion maturation and release) that may account for cell type-dependent viral growth kinetics. The possibility that cell type-specific differences in expressed cellular factors are responsible for modulation of viral gene expression is discussed.
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Affiliation(s)
- James C Towler
- MRC - University of Glasgow Centre for Virus Research, Glasgow G11 5JR, UK
| | - Bahram Ebrahimi
- Department of Functional and Comparative Genomics, Institute of Integrative Biology, University of Liverpool, Biosciences Building, Crown Street, Liverpool L69 7ZB, UK
| | - Brian Lane
- Liverpool Microarray Facility, Institute of Integrative Biology, University of Liverpool, Biosciences Building, Crown Street, Liverpool L69 7ZB, UK
| | - Andrew J Davison
- MRC - University of Glasgow Centre for Virus Research, Glasgow G11 5JR, UK
| | - Derrick J Dargan
- MRC - University of Glasgow Centre for Virus Research, Glasgow G11 5JR, UK
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Ma W, Zhao L, Wong WT. Microglia in the outer retina and their relevance to pathogenesis of age-related macular degeneration. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 723:37-42. [PMID: 22183313 DOI: 10.1007/978-1-4614-0631-0_6] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Age-related macular degeneration (AMD), the largest cause of legal blindness in the elderly in the Western world, is a disease whose pathogenesis is incompletely understood and for which therapeutic challenges remain. The etiology of AMD is thought to involve chronic neuroinflammation of the retina but the details of relevant cellular mechanisms are still not fully understood. Retinal microglia are the primary resident immune cell in the retina and are normally absent from the outer retina, the locus of AMD. Their migration and infiltration into the outer retina under conditions of advanced age and disease implicate their involvement in the neuroinflammatory etiology of AMD. We propose that interactions between microglia and RPE cells in the subretinal space result in significant alterations in the structure and physiology of RPE cells that in turn transforms the environment of the retino-choroidal interface into one conducive for the progression and advancement of AMD. In particular, microglia induce RPE alterations that result in a more chemoattractive, pro-inflammatory, and pro-angiogenic environment that increases the recruitment and activation of immune cells and fosters the growth of neovascular vessels into the retina. Microglia-to-RPE influences may represent a cell-cell interaction that may be targeted for therapeutic strategies to treat and/or prevent AMD.
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Affiliation(s)
- Wenxin Ma
- Unit on Neuron-Glia Interactions in Retinal Disease, National Eye Institute, 6 Center Drive, Building 6, Room 215, Bethesda, MD 20892, USA
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133
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Nag TC, Wadhwa S. WITHDRAWN: Ultrastructure of the human retina in aging and various pathological states. Micron 2011:S0968-4328(11)00226-5. [PMID: 22410275 DOI: 10.1016/j.micron.2011.12.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Accepted: 12/07/2011] [Indexed: 10/14/2022]
Abstract
This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.
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Affiliation(s)
- Tapas Chandra Nag
- Department of Anatomy, All India Institute of Medical Sciences, New Delhi, India
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Polyurethanes as supports for human retinal pigment epithelium cell growth. Int J Artif Organs 2011; 34:198-209. [PMID: 21374562 DOI: 10.5301/ijao.2011.6398] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/02/2010] [Indexed: 11/20/2022]
Abstract
PURPOSE The transplant of retinal pigment epithelium (RPE) cells on supports may well be an effective therapeutic approach to improve the visual results of patients with age-related macular degeneration. In this study, two biodegradable polyurethanes were investigated as supports for human RPE cells (ARPE-19). METHODS Polyurethane aqueous dispersions based on poly(caprolactone) and/or poly(ethylene glycol) as soft segments, and isophorone diisocyanate and hydrazine as hard segments were prepared. Polyurethane films were produced by casting the dispersions and allowing them to dry at room temperature for one week. The ARPE-19 cells were seeded onto the polyurethane films and they were investigated as supports for in vitro adhesion, proliferation, and uniform distribution of differentiated ARPE-19 cells. Additionally, the in vivo ocular biocompatibility of the polyurethane films was evaluated. RESULTS The RPE adhered to and proliferated onto the polyurethane supports, thus establishing cell-PUD surface interactions. Upon confluence, the cells formed an organized monolayer, exhibited a polygonal appearance, and displayed actin filaments which ran along the upper cytoplasm. At 15 days of seeding, the occluding expression was confirmed between adjacent cells, representing the barrier functionality of epithelial cells on polymeric surfaces and the establishment of cell-cell interactions. Results from the in vivo study indicated that polyurethanes exhibited a high degree of short-term intraocular biocompatibility. CONCLUSIONS Biodegradable polyurethane films display the proper mechanical properties for an easy transscleral-driven subretinal implantation and can be considered as biocompatible supports for a functional ARPE-19 monolayer.
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Monocyte/macrophages promote vasculogenesis in choroidal neovascularization in mice by stimulating SDF-1 expression in RPE cells. Graefes Arch Clin Exp Ophthalmol 2011; 249:1667-79. [DOI: 10.1007/s00417-011-1699-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 03/27/2011] [Accepted: 04/10/2011] [Indexed: 10/18/2022] Open
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Paimela T, Hyttinen JMT, Viiri J, Ryhänen T, Karjalainen RO, Salminen A, Kaarniranta K. Celastrol regulates innate immunity response via NF-κB and Hsp70 in human retinal pigment epithelial cells. Pharmacol Res 2011; 64:501-8. [PMID: 21683142 DOI: 10.1016/j.phrs.2011.05.027] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 05/25/2011] [Accepted: 05/31/2011] [Indexed: 12/22/2022]
Abstract
Elevated nuclear factor kappa B (NF-κB) activity and interleukin-6 (IL-6) secretion participates in the pathology of several age and inflammatory-related diseases, including age-related macular degeneration (AMD), in which retinal pigment epithelial cells are the key target. Recent findings reveal that heat shock protein 70 (Hsp70) may affect regulation of NF-κB. In the current study, effects of Hsp70 expression on NF-κB RelA/p65 activity were evaluated in human retinal pigment epithelial cells (ARPE-19) by using celastrol, a novel anti-inflammatory compound. Anti-inflammatory properties of celastrol were determined by measuring expression levels of IL-6 and endogenous NF-κB levels during lipopolysaccharide (LPS) exposure by using enzyme-linked immunosorbent assays (ELISA). Cell viability was measured by MTT and LDH assay, and Hsp70 expression levels were analyzed by Western blotting. ARPE-19 cells were transfected with hsp70 small interfering RNA (siRNA) in order to attenuate Hsp70 expression and activity of NF-κB RelA/p65 was measured using NF-κB consensus bound ELISA. Simultaneous exposures to LPS and celastrol reduced IL-6 expression levels as well as activity of phosphorylated NF-κB at serine 536 (Ser536) in ARPE-19 cells when compared to LPS exposure alone. In addition, inhibition of NF-κB RelA/p65 activity by celastrol was attenuated when Hsp70 response was silenced by siRNA. Favorable anti-inflammatory concentrations of celastrol showed no signs of cytotoxic response. Our findings reveal that celastrol is a novel plant compound which suppresses innate immunity response in human retinal pigment epithelial cells via NF-κB and Hsp70 regulation, and that Hsp70 is a critical regulator of NF-κB.
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Affiliation(s)
- Tuomas Paimela
- Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, P.O. Box 1627, FIN-70211 Kuopio, Finland
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Rutar M, Natoli R, Valter K, Provis JM. Early focal expression of the chemokine Ccl2 by Müller cells during exposure to damage-inducing bright continuous light. Invest Ophthalmol Vis Sci 2011; 52:2379-88. [PMID: 21228381 DOI: 10.1167/iovs.10-6010] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
PURPOSE To investigate the time course and localization of Ccl2 expression and recruitment of inflammatory cells associated with light-induced photoreceptor degeneration. METHODS Sprague-Dawley (SD) rats were exposed to 1000 lux light for up to 24 hours, after which some animals were allowed to recover in dim light (5 lux) for 3 or 7 days. During and after exposure to light, the animals were euthanatized and the retinas processed. Ccl2 expression was assessed by qPCR, immunohistochemistry, and in situ hybridization at each time point. Counts were made of perivascular monocytes/microglia immunolabeled with ED1, and photoreceptor apoptosis was assessed with TUNEL. RESULTS Upregulation of Ccl2 expression was evident in the retina by 12 hours of exposure and correlated with increased photoreceptor death. Ccl2 expression reached its maximum at 24 hours, coinciding with peak cell death. Immunohistochemistry and in situ hybridization showed that Ccl2 is expressed by Müller cells from 12 hours of exposure, most intensely in the superior retina, in the region of the incipient light-induced lesion. After the Müller cell-driven expression of Ccl2, there was a substantial recruitment of monocytes to the local retina and choroidal vasculature. This coincided spatially with the expression of Ccl2 in the superior retina. Peak monocyte infiltration followed maximum Ccl2 expression by up to 3 days. Furthermore, Ccl2 immunoreactivity was observed in many infiltrating monocytes after a 24-hour exposure. CONCLUSIONS The data indicate that photoreceptor death promotes region-specific expression of Ccl2 by Müller cells, which facilitates targeting of monocytes to sites of injury. The data suggest that recruitment of monocytes to developing lesions is secondary to signaling events in the retina.
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Affiliation(s)
- Matt Rutar
- Research School of Biology, The Australian National University, Canberra ACT 0200, Australia.
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138
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Chen Y, Yang P, Li F, Kijlstra A. The effects of Th17 cytokines on the inflammatory mediator production and barrier function of ARPE-19 cells. PLoS One 2011; 6:e18139. [PMID: 21479174 PMCID: PMC3068165 DOI: 10.1371/journal.pone.0018139] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Accepted: 02/25/2011] [Indexed: 11/19/2022] Open
Abstract
Th17 cells have emerged as a key factor in the pathogenesis of uveitis as well as other autoimmune disorders. They secrete a number of cytokines including IL-17A, IL-17F and IL-22 and until now the effects of these cytokines on resident cells of the eye were not yet clear. The purpose of this study was to investigate the effects of Interleukin (IL)-17A, IL-17F and IL-22 on the production of inflammatory mediators and barrier function of retinal pigment epithelium cells. We showed that ARPE-19 cells, a spontaneously arisen cell line of retinal pigment epithelium (RPE), constitutively expressed IL-17RC and IL-22R, but not IL-17RA. IL-17A significantly enhanced the production of CXCL8, CCL2, CCL20 and IL-6 by these cells. IL-17F had a similar effect on the production of CXCL8, CCL2 and IL-6 by ARPE-19 cells, but did not influence the expression of CCL20. Both IL-17A and IL-17F significantly decreased the transepithelial electrical resistance (TER) of the ARPE-19 monolayer and increased the diffusion rate of fluorescein isothiocyanate (FITC)-dextran. They also disrupted the distribution of the junction proteins zonula occludens (ZO)-1 and occludin at the interface of adjacent cells. IL-22 did not have a detectable effect on the production of the tested inflammatory mediators by ARPE-19 cells, TER of the ARPE-19 monolayer, the diffusion rate of FITC-dextran or the distribution of ZO-1 and occludin. This study demonstrates that IL-17A and IL-17F, but not IL-22, significantly promoted ARPE-19 cells to secrete inflammatory mediators and compromised the ARPE-19 monolayer barrier function in association with a disrupted distribution of ZO-1 and occludin. These results suggest that both IL-17A and IL-17F may play a role in posterior segment inflammation of the eye.
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Affiliation(s)
- Ying Chen
- Chongqing Key Laboratory of Ophthalmology, Chongqing Eye Institute, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China
- Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, People's Republic of China
| | - Peizeng Yang
- Chongqing Key Laboratory of Ophthalmology, Chongqing Eye Institute, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China
| | - Fuzhen Li
- Chongqing Key Laboratory of Ophthalmology, Chongqing Eye Institute, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China
| | - Aize Kijlstra
- Department of Ophthalmology, Eye Research Institute Maastricht, University Hospital Maastricht, Maastricht, The Netherlands
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Xu J, Zhu D, He S, Spee C, Ryan SJ, Hinton DR. Transcriptional regulation of bone morphogenetic protein 4 by tumor necrosis factor and its relationship with age-related macular degeneration. FASEB J 2011; 25:2221-33. [PMID: 21411747 DOI: 10.1096/fj.10-178350] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Bone morphogenetic protein-4 (BMP4) may be involved in the molecular switch that determines which late form of age-related macular degeneration (AMD) an individual develops. BMP4 expression is high in retinal pigment epithelium (RPE) cells in late, dry AMD patients, while BMP4 expression is low in the wet form of the disease, characterized by choroidal neovascularization (CNV). Here, we sought to determine the mechanism by which BMP4 is down-regulated in CNV. BMP4 expression was decreased within laser-induced CNV lesions in mice at a time when tumor necrosis factor (TNF) expression was high (7 d postlaser) and was reexpressed in RPE when TNF levels declined (14 d postlaser). We found that TNF, an important angiogenic stimulus, significantly down-regulates BMP4 expression in cultured human fetal RPE cells, ARPE-19 cells, and RPE cells in murine posterior eye cup explants. We identified two specificity protein 1 (Sp1) binding sites in the BMP4 promoter that are required for basal expression of BMP4 and its down-regulation by TNF. Through c-Jun NH(2)-terminal kinase (JNK) activation, TNF modulates Sp1 phosphorylation, thus decreasing its affinity to the BMP4 promoter. The down-regulation of BMP4 expression by TNF in CNV and mechanisms established might be useful for defining novel targets for AMD therapy.
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Affiliation(s)
- Jing Xu
- Neuroscience Graduate Program, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
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140
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Retinal pigment epithelial cells upregulate expression of complement factors after co-culture with activated T cells. Exp Eye Res 2011; 92:180-8. [PMID: 21255569 DOI: 10.1016/j.exer.2011.01.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Revised: 01/06/2011] [Accepted: 01/06/2011] [Indexed: 12/22/2022]
Abstract
In this study we examined the effect of T cell-derived cytokines on retinal pigment epithelial (RPE) cells with respect to expression of complement components. We used an in vitro co-culture system in which CD3/CD28-activated human T cells were separated from the human RPE cell line (ARPE-19) by a membrane. Differential gene expression in the RPE cells of complement factor genes was identified using gene arrays, and selected gene transcripts were validated by q-RT-PCR. Protein expression was determined by ELISA and immunoblotting. Co-culture with activated T cells increased RPE mRNA and/or protein expression of complement components C3, factors B, H, H-like 1, CD46, CD55, CD59, and clusterin, in a dose-dependent manner. Soluble factors derived from activated T cells are capable of increasing expression of complement components in RPE cells. This is important for the further understanding of inflammatory ocular diseases such as uveitis and age-related macular degeneration.
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Garcia-Ramírez M, Villarroel M, Corraliza L, Hernández C, Simó R. Measuring permeability in human retinal epithelial cells (ARPE-19): implications for the study of diabetic retinopathy. Methods Mol Biol 2011; 763:179-94. [PMID: 21874452 DOI: 10.1007/978-1-61779-191-8_12] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The retinal pigment epithelium (RPE) is a specialized epithelium lying in the interface between the -neural retina and the choriocapillaris where it forms the outer blood-retinal barrier (BRB). The tight junctions (TJ)s expressed in the outer BRB control fluids and solutes that enter the retina and this sealing function, which is essential for the retinal homeostasis, is impaired in diabetic retinopathy. In this -chapter, we provide the methods to explore the function of the RPE barrier by measuring Transepithelial electrical resistance (TER) and paracellular permeability to dextran in cultures of ARPE-19 cells (an immortalized RPE cell line). A method for inducing a lesion mimicking which occurs in diabetic retinopathy is described. In addition, methods for assessing mRNA expression and protein content of the main TJ proteins (occludin, zonula occludens-1 [ZO-1]) are detailed. Finally, we provide the methods required for confocal immunofluorescence detection of the TJ proteins, as well as for assessing the capacity of ARPE-19 cells to retain their functional properties.
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Affiliation(s)
- Marta Garcia-Ramírez
- Diabetes and Metabolism Research Unit, Institut de Recerca Hospital Universitari Vall d'Hebron, Universitat Autònoma de Barcelona and CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos III (ISCIII), Barcelona, Spain
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142
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Mitra S, Cheng KW, Mills GB. Rab GTPases implicated in inherited and acquired disorders. Semin Cell Dev Biol 2010; 22:57-68. [PMID: 21147240 DOI: 10.1016/j.semcdb.2010.12.005] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2010] [Revised: 12/06/2010] [Accepted: 12/06/2010] [Indexed: 01/05/2023]
Abstract
The endocytotic machinery imports, transports and exports receptors and associated molecules between the plasma membrane and various cytoplasmic chambers resulting in selective recycling, degradation, or secretion of molecules and signaling complexes. Trafficking of receptors, growth factors, nutrients, cytokines, integrins as well as pathogens dictates the kinetics and magnitude of signal transduction cascades. Understandably, alterations in the 'fate' of such cargo complexes have profound physiologic and pathophysiologic implications. Rab GTPases regulate endocytosis by decorating intracellular vesicles and targeting these vesicles along with their cargoes to appropriate subcellular compartments. In the last decade, the number of genetic diseases driven by germline mutations in Rab GTPases or their interacting proteins, has increased and there is growing evidence of aberrant Rab GTPase function in acquired pathophysiologies such as immune deficiency, infection, obesity, diabetes and cancer.
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Affiliation(s)
- Shreya Mitra
- Department of Systems Biology, The University of Texas, MD Anderson Cancer Center, Houston, TX 77054-1942, USA.
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143
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The retinal pigment epithelium: something more than a constituent of the blood-retinal barrier--implications for the pathogenesis of diabetic retinopathy. J Biomed Biotechnol 2010; 2010:190724. [PMID: 20182540 PMCID: PMC2825554 DOI: 10.1155/2010/190724] [Citation(s) in RCA: 308] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2009] [Revised: 09/28/2009] [Accepted: 11/16/2009] [Indexed: 12/27/2022] Open
Abstract
The retinal pigment epithelium (RPE) is an specialized epithelium lying in the interface between the neural retina and the choriocapillaris where it forms the outer blood-retinal barrier (BRB). The main functions of the RPE are the following: (1) transport of nutrients, ions, and water, (2) absorption of light and protection against photooxidation, (3) reisomerization of all-trans-retinal into 11-cis-retinal, which is crucial for the visual cycle, (4) phagocytosis of shed photoreceptor membranes, and (5) secretion of essential factors for the structural integrity of the retina. An overview of these functions will be given. Most of the research on the physiopathology of diabetic retinopathy has been focused on the impairment of the neuroretina and the breakdown of the inner BRB. By contrast, the effects of diabetes on the RPE and in particular on its secretory activity have received less attention. In this regard, new therapeutic strategies addressed to modulating RPE impairment are warranted.
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144
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Ma W, Zhao L, Fontainhas AM, Fariss RN, Wong WT. Microglia in the mouse retina alter the structure and function of retinal pigmented epithelial cells: a potential cellular interaction relevant to AMD. PLoS One 2009; 4:e7945. [PMID: 19936204 PMCID: PMC2775955 DOI: 10.1371/journal.pone.0007945] [Citation(s) in RCA: 166] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2009] [Accepted: 10/12/2009] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Age-related macular degeneration (AMD) is a leading cause of legal blindness in the elderly in the industrialized word. While the immune system in the retina is likely to be important in AMD pathogenesis, the cell biology underlying the disease is incompletely understood. Clinical and basic science studies have implicated alterations in the retinal pigment epithelium (RPE) layer as a locus of early change. Also, retinal microglia, the resident immune cells of the retina, have been observed to translocate from their normal position in the inner retina to accumulate in the subretinal space close to the RPE layer in AMD eyes and in animal models of AMD. METHODOLOGY/PRINCIPAL FINDINGS In this study, we examined the effects of retinal microglia on RPE cells using 1) an in vitro model where activated retinal microglia are co-cultured with primary RPE cells, and 2) an in vivo mouse model where retinal microglia are transplanted into the subretinal space. We found that retinal microglia induced in RPE cells 1) changes in RPE structure and distribution, 2) increased expression and secretion of pro-inflammatory, chemotactic, and pro-angiogenic molecules, and 3) increased extent of in vivo choroidal neovascularization in the subretinal space. CONCLUSIONS/SIGNIFICANCE These findings share similarities with important pathological features found in AMD and suggest the relevance of microglia-RPE interactions in AMD pathogenesis. We speculate that the migration of retinal microglia into the subretinal space in early stages of the disease induces significant changes in RPE cells that perpetuate further microglial accumulation, increase inflammation in the outer retina, and fosters an environment conducive for the formation of neovascular changes responsible for much of vision loss in advanced AMD.
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Affiliation(s)
- Wenxin Ma
- Unit on Neuron-Glia Interactions in Retinal Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Lian Zhao
- Unit on Neuron-Glia Interactions in Retinal Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Aurora M. Fontainhas
- Unit on Neuron-Glia Interactions in Retinal Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Robert N. Fariss
- Biological Imaging Core, Office of the Scientific Director, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Wai T. Wong
- Unit on Neuron-Glia Interactions in Retinal Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America
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145
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Gordiyenko NV, Fariss RN, Zhi C, MacDonald IM. Silencing of the CHM gene alters phagocytic and secretory pathways in the retinal pigment epithelium. Invest Ophthalmol Vis Sci 2009; 51:1143-50. [PMID: 19741243 DOI: 10.1167/iovs.09-4117] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Choroideremia (CHM) is an X-linked progressive degeneration of the retinal pigment epithelium (RPE), photoreceptors, and choroid caused by mutations in the CHM gene, which encodes Rab escort-protein-1 (REP-1). REP-1 enables posttranslational isoprenyl modification of Rab GTPases, proteins that control vesicle formation, movement, docking, and fusion. The aim of this study was to determine the effect of REP-1 depletion on vesicular trafficking in phagocytic and secretory pathways of human RPE. METHODS In vitro, REP-1 expression was inhibited in human fetal RPE (hfRPE) cells by siRNA knockdown and its effects measured on the uptake of bovine photoreceptor outer segments (POS), proteolysis of POS rhodopsin, phagosomal pH, phagosome fusion with early and late endosomes/lysosomes, and polarized secretion of cytokines. RESULTS Depletion of REP-1 in human RPE cells did not affect POS internalization but reduced phagosomal acidification and delayed POS protein clearance. REP-1 depletion also caused a decrease in the association of POS-containing phagosomes with late endosomal markers (Rab7, LAMP-1) and increases in the secretion of monocyte chemotactic protein (MCP-1) and interleukin (IL)-8 by hfRPE cells. CONCLUSIONS Lack of REP-1 protein expression in hfRPE cells leads to reduced degradation of POS most likely because of the inhibition of phagosome-lysosome fusion events and increased constitutive secretion of MCP-1 and IL-8. These observations may explain the accumulation of unprocessed outer segments within the phagolysosomes of RPE cells and the presence of inflammatory cells in the choroid of patients with CHM.
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Affiliation(s)
- Nataliya V Gordiyenko
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
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146
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Somatostatin analogues as therapeutics in retinal disease. Pharmacol Ther 2009; 122:324-33. [DOI: 10.1016/j.pharmthera.2009.03.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2009] [Accepted: 03/24/2009] [Indexed: 12/30/2022]
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147
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Functional annotation of the human retinal pigment epithelium transcriptome. BMC Genomics 2009; 10:164. [PMID: 19379482 PMCID: PMC2679759 DOI: 10.1186/1471-2164-10-164] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2008] [Accepted: 04/20/2009] [Indexed: 12/02/2022] Open
Abstract
Background To determine level, variability and functional annotation of gene expression of the human retinal pigment epithelium (RPE), the key tissue involved in retinal diseases like age-related macular degeneration and retinitis pigmentosa. Macular RPE cells from six selected healthy human donor eyes (aged 63–78 years) were laser dissected and used for 22k microarray studies (Agilent technologies). Data were analyzed with Rosetta Resolver, the web tool DAVID and Ingenuity software. Results In total, we identified 19,746 array entries with significant expression in the RPE. Gene expression was analyzed according to expression levels, interindividual variability and functionality. A group of highly (n = 2,194) expressed RPE genes showed an overrepresentation of genes of the oxidative phosphorylation, ATP synthesis and ribosome pathways. In the group of moderately expressed genes (n = 8,776) genes of the phosphatidylinositol signaling system and aminosugars metabolism were overrepresented. As expected, the top 10 percent (n = 2,194) of genes with the highest interindividual differences in expression showed functional overrepresentation of the complement cascade, essential in inflammation in age-related macular degeneration, and other signaling pathways. Surprisingly, this same category also includes the genes involved in Bruch's membrane (BM) composition. Among the top 10 percent of genes with low interindividual differences, there was an overrepresentation of genes involved in local glycosaminoglycan turnover. Conclusion Our study expands current knowledge of the RPE transcriptome by assigning new genes, and adding data about expression level and interindividual variation. Functional annotation suggests that the RPE has high levels of protein synthesis, strong energy demands, and is exposed to high levels of oxidative stress and a variable degree of inflammation. Our data sheds new light on the molecular composition of BM, adjacent to the RPE, and is useful for candidate retinal disease gene identification or gene dose-dependent therapeutic studies.
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148
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Kang KH, Lemke G, Kim JW. The PI3K-PTEN tug-of-war, oxidative stress and retinal degeneration. Trends Mol Med 2009; 15:191-8. [PMID: 19380252 DOI: 10.1016/j.molmed.2009.03.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Revised: 03/06/2009] [Accepted: 03/06/2009] [Indexed: 01/01/2023]
Abstract
The retinal pigment epithelium (RPE) is indispensable for photoreceptor function, not only because it provides functional photopigments to photoreceptors, but also because it eliminates oxidatively damaged materials from photoreceptors. Maintaining homeostatic antioxidative programs that support a healthy RPE is therefore important for the normal functioning of the eye. These homeostatic mechanisms, however, often fail in aged RPE cells that have been exposed repeatedly to excessive oxidative stress. When RPE cells succumb to oxidative stress, their death contributes to the development of retinal degenerative diseases such as age-related macular degeneration. Recent studies have highlighted the importance of reciprocal phosphoinositide signaling events orchestrated by phosphoinositide 3-kinase (PI3K) and phosphatase and tensin homolog (PTEN) in the homeostatic programs that protect RPE cells against oxidative stress. Here, we discuss the role of PI3K signaling pathways in RPE cells and suggest that they might be crucial targets of oxidative molecules that initiate early pathological events in retinal degenerative diseases.
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Affiliation(s)
- Kyung Hwa Kang
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 335 Gwahangno, Yuseong-gu, Daejeon 305-701, South Korea
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149
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Qin S, Rodrigues GA. Progress and perspectives on the role of RPE cell inflammatory responses in the development of age-related macular degeneration. J Inflamm Res 2008; 1:49-65. [PMID: 22096347 PMCID: PMC3218720 DOI: 10.2147/jir.s4354] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Age-related macular degeneration (AMD) is the leading cause of blindness in developed countries. The etiology of AMD remains poorly understood and no treatment is currently available for the atrophic form of AMD. Atrophic AMD has been proposed to involve abnormalities of the retinal pigment epithelium (RPE), which lies beneath the photoreceptor cells and normally provides critical metabolic support to these light-sensing cells. Cumulative oxidative stress and local inflammation are thought to represent pathological processes involved in the etiology of atrophic AMD. Studies of tissue culture and animal models reveal that oxidative stress-induced injury to the RPE results in a chronic inflammatory response, drusen formation, and RPE atrophy. RPE degeneration in turn causes a progressive degeneration of photoreceptors, leading to the irreversible loss of vision. This review describes some of the potential major molecular and cellular events contributing to RPE death and inflammatory responses. In addition, potential target areas for therapeutic intervention will be discussed and new experimental therapeutic strategies for atrophic AMD will be presented.
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Affiliation(s)
- Suofu Qin
- Retinal Disease Research, Department of Biological Sciences, Allergan, Inc., Irvine, CA, USA
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150
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Kaarniranta K, Salminen A. Age-related macular degeneration: activation of innate immunity system via pattern recognition receptors. J Mol Med (Berl) 2008; 87:117-23. [PMID: 19009282 DOI: 10.1007/s00109-008-0418-z] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2008] [Accepted: 10/29/2008] [Indexed: 12/25/2022]
Abstract
Age-related macular degeneration (AMD) is the most common cause of irreversible loss of central vision. Histopathological studies have demonstrated that inflammation is the key player in the pathogenesis of AMD. Genetic studies have revealed that complement factor H is a strong risk factor for the development of AMD. However, innate immunity defence involves several other pattern recognition receptors (PRRs) which can trigger inflammatory responses. Retinal pigment epithelial (RPE) cells have the main role in the immune defence in macula. In this study, we examine in detail the endogenous danger signals which can activate different PRRs in RPE cells, such as Toll-like, NOD-like and scavenger receptors along with complement system. We also characterise the signalling pathways triggered by PRRs in evoking inflammatory responses. In addition, we will discuss whether AMD pathology could represent the outcome of chronic activation of the innate immunity defence in human macula.
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Affiliation(s)
- K Kaarniranta
- Department of Ophthalmology, Institute of Clinical Medicine, University of Kuopio, P.O. Box 1627, 70211, Kuopio, Finland.
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