101
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Keeling E, Chatelet DS, Johnston DA, Page A, Tumbarello DA, Lotery AJ, Ratnayaka JA. Oxidative Stress and Dysfunctional Intracellular Traffic Linked to an Unhealthy Diet Results in Impaired Cargo Transport in the Retinal Pigment Epithelium (RPE). Mol Nutr Food Res 2019; 63:e1800951. [PMID: 30835933 DOI: 10.1002/mnfr.201800951] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 01/18/2019] [Indexed: 12/19/2022]
Abstract
SCOPE Oxidative stress and dysregulated intracellular trafficking are associated with an unhealthy diet which underlies pathology. Here, these effects on photoreceptor outer segment (POS) trafficking in the retinal pigment epithelium (RPE), a major pathway of disease underlying irreversible sight-loss, are studied. METHODS AND RESULTS POS trafficking is studied in ARPE-19 cells using an algorithm-based quantification of confocal-immunofluorescence data supported by ultrastructural studies. It is shown that although POS are tightly regulated and trafficked via Rab5, Rab7 vesicles, LAMP1/2 lysosomes and LC3b-autophagosomes, there is also a considerable degree of variation and flexibility in this process. Treatment with H2 O2 and bafilomycin A1 reveals that oxidative stress and dysregulated autophagy target intracellular compartments and trafficking in strikingly different ways. These effects appear limited to POS-containing vesicles, suggesting a cargo-specific effect. CONCLUSION The findings offer insights into how RPE cells cope with stress, and how mechanisms influencing POS transport/degradation can have different outcomes in the senescent retina. These shed new light on cellular processes underlying retinopathies such as age-related macular degeneration. The discoveries reveal how diet and nutrition can cause fundamental alterations at a cellular level, thus contributing to a better understanding of the diet-disease axis.
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Affiliation(s)
- Eloise Keeling
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, MP806, Tremona Road, SO16 6YD, UK
| | - David S Chatelet
- Biomedical Imaging Unit, University of Southampton, MP12, Tremona Road, SO16 6YD, UK
| | - David A Johnston
- Biomedical Imaging Unit, University of Southampton, MP12, Tremona Road, SO16 6YD, UK
| | - Anton Page
- Biomedical Imaging Unit, University of Southampton, MP12, Tremona Road, SO16 6YD, UK
| | - David A Tumbarello
- Biological Sciences, Faculty of Natural & Environmental Sciences, University of Southampton, Life Sciences Building 85, SO17 1BJ, UK
| | - Andrew J Lotery
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, MP806, Tremona Road, SO16 6YD, UK
- Eye Unit, University Hospital Southampton NHS Foundation Trust, Southampton, SO16 6YD, UK
| | - J Arjuna Ratnayaka
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, MP806, Tremona Road, SO16 6YD, UK
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102
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The Cytoskeleton of the Retinal Pigment Epithelium: from Normal Aging to Age-Related Macular Degeneration. Int J Mol Sci 2019; 20:ijms20143578. [PMID: 31336621 PMCID: PMC6678077 DOI: 10.3390/ijms20143578] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 07/15/2019] [Accepted: 07/18/2019] [Indexed: 12/15/2022] Open
Abstract
The retinal pigment epithelium (RPE) is a unique epithelium, with major roles which are essential in the visual cycle and homeostasis of the outer retina. The RPE is a monolayer of polygonal and pigmented cells strategically placed between the neuroretina and Bruch membrane, adjacent to the fenestrated capillaries of the choriocapillaris. It shows strong apical (towards photoreceptors) to basal/basolateral (towards Bruch membrane) polarization. Multiple functions are bound to a complex structure of highly organized and polarized intracellular components: the cytoskeleton. A strong connection between the intracellular cytoskeleton and extracellular matrix is indispensable to maintaining the function of the RPE and thus, the photoreceptors. Impairments of these intracellular structures and the regular architecture they maintain often result in a disrupted cytoskeleton, which can be found in many retinal diseases, including age-related macular degeneration (AMD). This review article will give an overview of current knowledge on the molecules and proteins involved in cytoskeleton formation in cells, including RPE and how the cytoskeleton is affected under stress conditions—especially in AMD.
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103
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Muniz-Feliciano L, Doggett TA, Zhou Z, Ferguson TA. RUBCN/rubicon and EGFR regulate lysosomal degradative processes in the retinal pigment epithelium (RPE) of the eye. Autophagy 2019; 13:2072-2085. [PMID: 28933590 DOI: 10.1080/15548627.2017.1380124] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Macroautophagy/autophagy is an intracellular stress survival and recycling system whereas phagocytosis internalizes material from the extracellular milieu; yet, both pathways utilize lysosomes for cargo degradation. Whereas autophagy occurs in all cells, phagocytosis is performed by cell types such as macrophages and the retinal pigment epithelial (RPE) cells of the eye where it is supported by the noncanonical autophagy process termed LC3-associated phagocytosis (LAP). Autophagy and LAP are distinct pathways that use many of the same mediators and must compete for cellular resources, suggesting that cells may regulate both processes under homeostatic and stress conditions. Our data reveal that RPE cells promote LAP through the expression of RUBCN/Rubicon (RUN domain and cysteine-rich domain containing Beclin 1-interacting protein) and suppress autophagy through the activation of EGFR (epidermal growth factor receptor). In the morning when photoreceptor outer segments (POS) phagocytosis and LAP are highest, RUBCN expression is increased. At the same time, outer segment phagocytosis activates the EGFR resulting in MTOR (mechanistic target of rapamycin [serine/threonine kinase]) stimulation, the accumulation of SQSTM1/p62, and the phosphorylation of BECN1 (Beclin 1, autophagy related) on an inhibitory residue thereby suppressing autophagy. Silencing Rubcn, preventing EGFR activity or directly inducing autophagy in RPE cells by starvation inhibits phagocytic degradation of POS. Thus, RPE cells regulate lysosomal pathways during the critical period of POS phagocytosis to support retinal homeostasis.
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Affiliation(s)
- Luis Muniz-Feliciano
- a Department of Ophthalmology and Visual Sciences , Washington University School of Medicine , St. Louis , Missouri , USA
| | - Teresa A Doggett
- a Department of Ophthalmology and Visual Sciences , Washington University School of Medicine , St. Louis , Missouri , USA
| | - Zhenqing Zhou
- a Department of Ophthalmology and Visual Sciences , Washington University School of Medicine , St. Louis , Missouri , USA
| | - Thomas A Ferguson
- a Department of Ophthalmology and Visual Sciences , Washington University School of Medicine , St. Louis , Missouri , USA
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104
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Zhang W, Wang Y, Kong Y. Exosomes Derived From Mesenchymal Stem Cells Modulate miR-126 to Ameliorate Hyperglycemia-Induced Retinal Inflammation Via Targeting HMGB1. Invest Ophthalmol Vis Sci 2019; 60:294-303. [PMID: 30657854 DOI: 10.1167/iovs.18-25617] [Citation(s) in RCA: 146] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Purpose In this study, we aim to investigate whether mesenchymal stem cell (MSC)-derived exosomes (MSC-Exos) could regulate hyperglycemia-induced retinal inflammation by transferring microRNA-126 (miR-126). Methods MSC-Exos were isolated from the media of human umbilical cord-derived mesenchymal stem cells (hUCMSCs), and this isolation was followed by the transfer of miR-126. MSC-Exos or MSC-Exos overexpressing miR-126 were intravitreally injected into diabetic rats in vivo and were cocultured with high glucose-affected human retinal endothelial cells (HRECs) in vitro. Plasma samples were obtained from the vitreous of rats and from HREC cells after treatment for ELISA assay. Retinal sections were examined using immunohistochemistry. RT-PCR and Western blotting were conducted to assess the levels of high-mobility group box 1 (HMGB1), NLRP3 inflammasome, and NF-κB/P65 in retinas and HRECs. Results Our results showed that hyperglycemia greatly increased inflammation in diabetic rats or HRECs exposed to high glucose, increasing the levels of caspase-1, interleukin-1β (IL-1β) and IL-18. The administration of MSC-Exos could effectively reverse this reaction. Compared to control MSC-Exos, MSC-Exos overexpressing miR-126 more successfully suppressed the HMGB1 signaling pathway and suppressed inflammation in diabetic rats. The administration of miR-126-expressing MSC-Exos significantly reduced high glucose-induced HMGB1 expression and the activity of the NLRP3 inflammasome in HRECs. Conclusions miR-126 expression in MSC-Exos reduces hyperglycemia-induced retinal inflammation by downregulating the HMGB1 signaling pathway.
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Affiliation(s)
- Wei Zhang
- Tianjin Eye Hospital, Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Institute, Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China
| | - Yang Wang
- Department of Ophthalmology, Tianjin Medical University General Hospital, Tianjin, China
| | - Yichun Kong
- Tianjin Eye Hospital, Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Institute, Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China
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105
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Akhtar-Schäfer I, Wang L, Krohne TU, Xu H, Langmann T. Modulation of three key innate immune pathways for the most common retinal degenerative diseases. EMBO Mol Med 2019; 10:emmm.201708259. [PMID: 30224384 PMCID: PMC6180304 DOI: 10.15252/emmm.201708259] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
This review highlights the role of three key immune pathways in the pathophysiology of major retinal degenerative diseases including diabetic retinopathy, age‐related macular degeneration, and rare retinal dystrophies. We first discuss the mechanisms how loss of retinal homeostasis evokes an unbalanced retinal immune reaction involving responses of local microglia and recruited macrophages, activity of the alternative complement system, and inflammasome assembly in the retinal pigment epithelium. Presenting these key mechanisms as complementary targets, we specifically emphasize the concept of immunomodulation as potential treatment strategy to prevent or delay vision loss. Promising molecules are ligands for phagocyte receptors, specific inhibitors of complement activation products, and inflammasome inhibitors. We comprehensively summarize the scientific evidence for this strategy from preclinical animal models, human ocular tissue analyses, and clinical trials evolving in the last few years.
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Affiliation(s)
- Isha Akhtar-Schäfer
- Laboratory for Experimental Immunology of the Eye, Department of Ophthalmology, University of Cologne, Cologne, Germany
| | - Luping Wang
- Department of Ophthalmology, University of Bonn, Bonn, Germany
| | - Tim U Krohne
- Department of Ophthalmology, University of Bonn, Bonn, Germany
| | - Heping Xu
- Centre for Experimental Medicine, The Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry & Biomedical Sciences, Queen's University Belfast, Belfast, UK
| | - Thomas Langmann
- Laboratory for Experimental Immunology of the Eye, Department of Ophthalmology, University of Cologne, Cologne, Germany .,Center for Molecular Medicine, University of Cologne, Cologne, Germany
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106
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Bermúdez V, Tenconi PE, Giusto NM, Mateos MV. Lipopolysaccharide-Induced Autophagy Mediates Retinal Pigment Epithelium Cells Survival. Modulation by the Phospholipase D Pathway. Front Cell Neurosci 2019; 13:154. [PMID: 31327962 PMCID: PMC6497095 DOI: 10.3389/fncel.2019.00154] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Accepted: 04/08/2019] [Indexed: 12/12/2022] Open
Abstract
Inflammation and oxidative stress are common factors involved in the pathogenesis of retinal diseases, such as aged-related macular degeneration (AMD) and diabetic retinopathy (DR). Autophagy is a catabolic process essential to cell survival in response to stress. This process is highly active in retinal pigment epithelium (RPE) cells. Our previous findings demonstrated that lipopolysaccharide (LPS) induces an inflammatory response of RPE cells that implies classical phospholipases D (PLD1 and 2) activation, cyclooxygenase-2 (COX-2) expression, prostaglandin E2 (PGE2) production and reduced cell viability. In this work, we studied the autophagic process and its modulation by the PLD pathway in D407 and ARPE-19 RPE cells exposed to LPS. LPS (10 μg/ml or 25 μg/ml) exposure for 24 h increased light chain 3B-II (LC3B-II) content (an autophagy marker) and LC3B-positive punctate structures in both RPE cell lines studied. Next, the drug bafilomycin A1 (BAF, 50 nM) was used to block the autophagic flux. In cells pre-incubated with BAF, LC3B-II and sequestosome 1 (SQSTM1/p62) levels and autophagosome-like structures were increased by LPS, demonstrating that the inflammatory injury increases the autophagic process in RPE cells. To study the role of the PLD pathway, cells were pre-incubated for 1 h with selective PLD1 (VU0359595) or PLD2 (VU0285655-1) inhibitors prior to LPS addition. Under control condition, LC3B-positive punctate structures were increased in cells pre-incubated with PLD2 inhibitor while with PLD1 inhibitor were increased in cells exposed to LPS. MTT reduction assays showed that early autophagy inhibitors, 3-methyladenin (3-MA) or LY294002, enhanced the loss in cell viability induced by LPS exposure for 48 h. On the contrary, the inhibition of PLD1 and PLD2 prevented the loss in cell viability induced by LPS. In conclusion, our results show that even though LPS treatment promotes an inflammatory response in RPE cells, it also triggers the activation of the autophagic process which in turn may serve as a protective mechanism for the cells. In addition, we demonstrate that the PLD pathway modulates the autophagic process in RPE cells. Our findings contribute to the knowledge of the molecular basis of retinal inflammatory and degenerative diseases and open new avenues for potential therapeutic exploration.
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Affiliation(s)
- Vicente Bermúdez
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina.,Departamento de Biología, Bioquímica y Farmacia (DBByF), Universidad Nacional del Sur (UNS), Bahía Blanca, Argentina
| | - Paula Estefanía Tenconi
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina.,Departamento de Biología, Bioquímica y Farmacia (DBByF), Universidad Nacional del Sur (UNS), Bahía Blanca, Argentina
| | - Norma María Giusto
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina.,Departamento de Biología, Bioquímica y Farmacia (DBByF), Universidad Nacional del Sur (UNS), Bahía Blanca, Argentina
| | - Melina Valeria Mateos
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca, Argentina.,Departamento de Biología, Bioquímica y Farmacia (DBByF), Universidad Nacional del Sur (UNS), Bahía Blanca, Argentina
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107
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Szatmári-Tóth M, Ilmarinen T, Mikhailova A, Skottman H, Kauppinen A, Kaarniranta K, Kristóf E, Lytvynchuk L, Veréb Z, Fésüs L, Petrovski G. Human Embryonic Stem Cell-Derived Retinal Pigment Epithelium-Role in Dead Cell Clearance and Inflammation. Int J Mol Sci 2019; 20:ijms20040926. [PMID: 30791639 PMCID: PMC6412543 DOI: 10.3390/ijms20040926] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 12/19/2018] [Accepted: 02/13/2019] [Indexed: 12/19/2022] Open
Abstract
Inefficient removal of dying retinal pigment epithelial (RPE) cells by professional phagocytes can result in debris formation and development of age-related macular degeneration (AMD). Chronic oxidative stress and inflammation play an important role in AMD pathogenesis. Only a few well-established in vitro phagocytosis assay models exist. We propose human embryonic stem cell-derived-RPE cells as a new model for studying RPE cell removal by professional phagocytes. The characteristics of human embryonic stem cells-derived RPE (hESC-RPE) are similar to native RPEs based on their gene and protein expression profile, integrity, and barrier properties or regarding drug transport. However, no data exist about RPE death modalities and how efficiently dying hESC-RPEs are taken upby macrophages, and whether this process triggers an inflammatory responses. This study demonstrates hESC-RPEs can be induced to undergo anoikis or autophagy-associated cell death due to extracellular matrix detachment or serum deprivation and hydrogen-peroxide co-treatment, respectively, similar to primary human RPEs. Dying hESC-RPEs are efficiently engulfed by macrophages which results in high amounts of IL-6 and IL-8 cytokine release. These findings suggest that the clearance of anoikic and autophagy-associated dying hESC-RPEs can be used as a new model for investigating AMD pathogenesis or for testing the in vivo potential of these cells in stem cell therapy.
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Affiliation(s)
- Mária Szatmári-Tóth
- Department of Biochemistry and Molecular Biology, University of Debrecen, Faculty of Medicine, 4032 Debrecen, Hungary.
| | - Tanja Ilmarinen
- Tampere University, Faculty of Medicine and Health Technology, 33014 Tampere, Finland.
| | - Alexandra Mikhailova
- Tampere University, Faculty of Medicine and Health Technology, 33014 Tampere, Finland.
| | - Heli Skottman
- Tampere University, Faculty of Medicine and Health Technology, 33014 Tampere, Finland.
| | - Anu Kauppinen
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, 70211 Kuopio, Finland.
| | - Kai Kaarniranta
- Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, 70211 Kuopio, Finland.
- Department of Ophthalmology, Kuopio University Hospital, 70029 Kuopio, Finland.
| | - Endre Kristóf
- Department of Biochemistry and Molecular Biology, University of Debrecen, Faculty of Medicine, 4032 Debrecen, Hungary.
| | - Lyubomyr Lytvynchuk
- Department of Ophthalmology, Justus-Liebig-University Giessen, Eye Clinic, University Hospital Giessen and Marburg GmbH, Campus Giessen, 35390 Giessen, Germany.
| | - Zoltán Veréb
- Department of Ophthalmology, Faculty of Medicine, University of Szeged, 6720 Szeged, Hungary.
| | - László Fésüs
- Department of Biochemistry and Molecular Biology, University of Debrecen, Faculty of Medicine, 4032 Debrecen, Hungary.
| | - Goran Petrovski
- Department of Biochemistry and Molecular Biology, University of Debrecen, Faculty of Medicine, 4032 Debrecen, Hungary.
- Department of Ophthalmology, Faculty of Medicine, University of Szeged, 6720 Szeged, Hungary.
- Center for Eye Research, Department of Ophthalmology, Oslo University Hospital and University of Oslo, Kirkeveien 166, 0450 Oslo, Norway.
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108
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Rudolf M, Curcio CA, Schlötzer-Schrehardt U, Sefat AMM, Tura A, Aherrahrou Z, Brinkmann M, Grisanti S, Miura Y, Ranjbar M. Apolipoprotein A-I Mimetic Peptide L-4F Removes Bruch's Membrane Lipids in Aged Nonhuman Primates. ACTA ACUST UNITED AC 2019; 60:461-472. [DOI: 10.1167/iovs.18-25786] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Martin Rudolf
- Department of Ophthalmology, University of Lübeck, Lübeck, Germany
- Translational AMD Research Group Lübeck, University of Lübeck, Lübeck, Germany
| | - Christine A. Curcio
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | | | - Armin Mir Mohi Sefat
- Department of Ophthalmology, University of Lübeck, Lübeck, Germany
- Translational AMD Research Group Lübeck, University of Lübeck, Lübeck, Germany
| | - Aysegül Tura
- Department of Ophthalmology, University of Lübeck, Lübeck, Germany
| | - Zouhair Aherrahrou
- Institute for Cardiogenetics, University of Lübeck, Lübeck, Germany
- German Centre for Cardiovascular Research, Partner Site Hamburg/Kiel/Lübeck, Germany
- University Heart Centre Lübeck, Lübeck, Germany
| | - Max Brinkmann
- Department of Ophthalmology, University of Lübeck, Lübeck, Germany
- Laboratory for Angiogenesis & Ocular Cell Transplantation, University of Lübeck, Lübeck, Germany
| | | | - Yoko Miura
- Department of Ophthalmology, University of Lübeck, Lübeck, Germany
- Translational AMD Research Group Lübeck, University of Lübeck, Lübeck, Germany
- Institute of Biomedical Optics, University of Lübeck, Lübeck, Germany
| | - Mahdy Ranjbar
- Department of Ophthalmology, University of Lübeck, Lübeck, Germany
- Laboratory for Angiogenesis & Ocular Cell Transplantation, University of Lübeck, Lübeck, Germany
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109
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McKay BS. Pigmentation and vision: Is GPR143 in control? J Neurosci Res 2019; 97:77-87. [PMID: 29761529 PMCID: PMC6235735 DOI: 10.1002/jnr.24246] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 02/21/2018] [Accepted: 03/21/2018] [Indexed: 12/30/2022]
Abstract
Albinism, typically characterized by decreased melanin synthesis, is associated with significant visual deficits owing to developmental changes during neurosensory retina development. All albinism is caused by genetic mutations in a group of diverse genes including enzymes, transporters, G-protein coupled receptor. Interestingly, these genes are not expressed in the neurosensory retina. Further, regardless of cause of albinism, all forms of albinism have the same retinal pathology, the extent of which is variable. In this review, we explore the possibility that this similarity in retinal phenotype is because all forms of albinism funnel through the same final common pathway. There are currently seven known genes linked to the seven forms of ocular cutaneous albinism. These types of albinism are the most common, and result in changes to all pigmented tissues (hair, skin, eyes). We will discuss the incidence and mechanism, where known, to develop a picture as to how the mutations cause albinism. Next, we will examine the one form of albinism which causes tissue-specific pathology, ocular albinism, where the eye exhibits the retinal albinism phenotype despite near normal melanin synthesis. We will discuss a potential way to treat the disease and restore normal retinal development. Finally, we will briefly discuss the possibility that this same pathway may intersect with the most common cause of permanent vision loss in the elderly.
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Affiliation(s)
- Brian S McKay
- Department of Ophthalmology and Vision Science, University of Arizona, Tucson, Arizona
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110
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Dalvi S, Galloway CA, Singh R. Pluripotent Stem Cells to Model Degenerative Retinal Diseases: The RPE Perspective. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1186:1-31. [PMID: 31654384 DOI: 10.1007/978-3-030-28471-8_1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Pluripotent stem cell technology, including human-induced pluripotent stem cells (hiPSCs) and human embryonic stem cells (hESCs), has provided a suitable platform to investigate molecular and pathological alterations in an individual cell type using patient's own cells. Importantly, hiPSCs/hESCs are amenable to genome editing providing unique access to isogenic controls. Specifically, the ability to introduce disease-causing mutations in control (unaffected) and conversely correct disease-causing mutations in patient-derived hiPSCs has provided a powerful approach to clearly link the disease phenotype with a specific gene mutation. In fact, utilizing hiPSC/hESC and CRISPR technology has provided significant insight into the pathomechanism of several diseases. With regard to the eye, the use of hiPSCs/hESCs to study human retinal diseases is especially relevant to retinal pigment epithelium (RPE)-based disorders. This is because several studies have now consistently shown that hiPSC-RPE in culture displays key physical, gene expression and functional attributes of human RPE in vivo. In this book chapter, we will discuss the current utility, limitations, and plausible future approaches of pluripotent stem cell technology for the study of retinal degenerative diseases. Of note, although we will broadly summarize the significant advances made in modeling and studying several retinal diseases utilizing hiPSCs/hESCs, our specific focus will be on the utility of patient-derived hiPSCs for (1) establishment of human cell models and (2) molecular and pharmacological studies on patient-derived cell models of retinal degenerative diseases where RPE cellular defects play a major pathogenic role in disease development and progression.
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Affiliation(s)
- Sonal Dalvi
- Department of Ophthalmology, Flaum Eye Institute, University of Rochester, Rochester, NY, USA.,Department of Biomedical Genetics, University of Rochester, Rochester, NY, USA
| | - Chad A Galloway
- Department of Ophthalmology, Flaum Eye Institute, University of Rochester, Rochester, NY, USA.,Department of Biomedical Genetics, University of Rochester, Rochester, NY, USA
| | - Ruchira Singh
- Department of Ophthalmology, Flaum Eye Institute, University of Rochester, Rochester, NY, USA. .,Department of Biomedical Genetics, University of Rochester, Rochester, NY, USA. .,UR Stem Cell and Regenerative Medicine Institute, Rochester, NY, USA. .,Center for Visual Science, University of Rochester, Rochester, NY, USA.
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111
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Xu K, Guo Y, Li Z, Wang Z. Aging Biomarkers and Novel Targets for Anti-Aging Interventions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1178:39-56. [PMID: 31493221 DOI: 10.1007/978-3-030-25650-0_3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The aging population worldwide is expanding at an increasing rate. By 2050, approximately a quarter of the world population will consist of the elderly. To slow down the aging process, exploration of aging biomarkers and the search for novel antiaging targets have attracted much interest. Nonetheless, because aging research is costly and time-consuming and the aging process is complicated, aging research is considered one of the most difficult biological fields. Here, providing a broader definition of aging biomarkers, we review cutting-edge research on aging biomarkers at the molecular, cellular, and organismal levels, thus shedding light on the relations between aging and telomeres, longevity proteins, a senescence-associated secretory phenotype, the gut microbiota and metabolic patterns. Furthermore, we evaluate the suitability of these aging biomarkers for the development of novel antiaging targets on the basis of the most recent research on this topic. We also discuss the possible implications and some controversies regarding these biomarkers for therapeutic interventions in aging and age-related disease processes. We have attempted to cover all of the latest research on aging biomarkers in our review but there are countless studies on aging biomarkers, and the topic of aging interventions will continue to deepen even further. We hope that our review can serve as a reference for better characterization of aging and as inspiration for the screening of antiaging drugs as well as give some clues to further research into aging biomarkers and antiaging targets.
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Affiliation(s)
- Kang Xu
- Protein Science Key Laboratory of the Ministry of Education, School of Pharmaceutical Sciences, Tsinghua University, Beijing, People's Republic of China
| | - Yannan Guo
- Protein Science Key Laboratory of the Ministry of Education, School of Pharmaceutical Sciences, Tsinghua University, Beijing, People's Republic of China
| | - Zhongchi Li
- Protein Science Key Laboratory of the Ministry of Education, School of Pharmaceutical Sciences, Tsinghua University, Beijing, People's Republic of China
| | - Zhao Wang
- Protein Science Key Laboratory of the Ministry of Education, School of Pharmaceutical Sciences, Tsinghua University, Beijing, People's Republic of China.
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112
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Baksheeva VE, Tiulina VV, Tikhomirova NK, Gancharova OS, Komarov SV, Philippov PP, Zamyatnin AA, Senin II, Zernii EY. Suppression of Light-Induced Oxidative Stress in the Retina by Mitochondria-Targeted Antioxidant. Antioxidants (Basel) 2018; 8:E3. [PMID: 30577635 PMCID: PMC6356525 DOI: 10.3390/antiox8010003] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 12/03/2018] [Accepted: 12/13/2018] [Indexed: 01/06/2023] Open
Abstract
Light-induced oxidation of lipids and proteins provokes retinal injuries and results in progression of degenerative retinal diseases, such as, for instance, iatrogenic photic maculopathies. Having accumulated over years retinal injuries contribute to development of age-related macular degeneration (AMD). Antioxidant treatment is regarded as a promising approach to protecting the retina from light damage and AMD. Here, we examine oxidative processes induced in rabbit retina by excessive light illumination with or without premedication using mitochondria-targeted antioxidant SkQ1 (10-(6'-plastoquinonyl)decyltriphenyl-phosphonium). The retinal extracts obtained from animals euthanized within 1⁻7 days post exposure were analyzed for H₂O₂, malondialdehyde (MDA), total antioxidant activity (AOA), and activities of glutathione peroxidase (GPx) and superoxide dismutase (SOD) using colorimetric and luminescence assays. Oxidation of visual arrestin was monitored by immunoblotting. The light exposure induced lipid peroxidation and H₂O₂ accumulation in the retinal cells. Unexpectedly, it prominently upregulated AOA in retinal extracts although SOD and GPx activities were compromised. These alterations were accompanied by accumulation of disulfide dimers of arrestin revealing oxidative stress in the photoreceptors. Premedication of the eyes with SkQ1 accelerated normalization of H₂O₂ levels and redox-status of lipids and proteins, contemporarily enhancing AOA and, likely, sustaining normal activity of GPx. Thus, SkQ1 protects the retina from light-induced oxidative stress and could be employed to suppress oxidative damage of proteins and lipids contributing to AMD.
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Affiliation(s)
- Viktoriia E Baksheeva
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia.
| | - Veronika V Tiulina
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia.
| | - Natalia K Tikhomirova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia.
| | - Olga S Gancharova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia.
- Institute for Regenerative Medicine, Sechenov First Moscow State Medical University, Moscow 119991, Russia.
| | - Sergey V Komarov
- Department of Biology and Pathology of Domestic, Laboratory and Exotic Animals, Skryabin Moscow State Academy of Veterinary Medicine and Biotechnology, Moscow 109472, Russia.
| | - Pavel P Philippov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia.
| | - Andrey A Zamyatnin
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia.
- Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Moscow 119991, Russia.
| | - Ivan I Senin
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia.
| | - Evgeni Yu Zernii
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia.
- Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Moscow 119991, Russia.
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113
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Chen M, Luo C, Zhao J, Devarajan G, Xu H. Immune regulation in the aging retina. Prog Retin Eye Res 2018; 69:159-172. [PMID: 30352305 DOI: 10.1016/j.preteyeres.2018.10.003] [Citation(s) in RCA: 146] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 10/13/2018] [Accepted: 10/19/2018] [Indexed: 12/24/2022]
Abstract
The retina is an immune privileged tissue, which is protected from external and internal insults by its blood-retina barriers and immune suppressive microenvironment. Apart from the avoidance and tolerance strategies, the retina is also protected by its own defense system, i.e., microglia and the complement system. The immune privilege and defense mechanisms work together to maintain retinal homeostasis. During aging, the retina is at an increased risk of developing various degenerative diseases such as age-related macular degeneration, diabetic retinopathy, and glaucomatous retinopathy. Previously, we have shown that aging induces a para-inflammatory response in the retina. In this review, we explore the impact of aging on retinal immune regulation and the connection between homeostatic control of retinal immune privilege and para-inflammation under aging conditions and present a view that may explain why aging puts the retina at risk of developing degenerative diseases.
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Affiliation(s)
- Mei Chen
- Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Sciences, Queen's University Belfast, UK
| | - Chang Luo
- Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Sciences, Queen's University Belfast, UK; Aier Eye Institute, Aier School of Ophthalmology, Central South University, China
| | - Jiawu Zhao
- Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Sciences, Queen's University Belfast, UK
| | | | - Heping Xu
- Centre for Experimental Medicine, School of Medicine, Dentistry & Biomedical Sciences, Queen's University Belfast, UK; Aier Eye Institute, Aier School of Ophthalmology, Central South University, China.
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114
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Modenese A, Korpinen L, Gobba F. Solar Radiation Exposure and Outdoor Work: An Underestimated Occupational Risk. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2018; 15:E2063. [PMID: 30241306 PMCID: PMC6209927 DOI: 10.3390/ijerph15102063] [Citation(s) in RCA: 97] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 09/17/2018] [Accepted: 09/18/2018] [Indexed: 12/22/2022]
Abstract
A considerably high number of outdoor workers worldwide are constantly exposed for the majority of their working life to solar radiation (SR); this exposure is known to induce various adverse health effects, mainly related to its ultraviolet (UV) component. The skin and the eye are the principal target organs for both acute and long-term exposure. Actinic keratosis, non-melanoma skin cancers, and malignant melanoma are the main long-term adverse skin effects, whereas in the eye pterygium, cataracts, and according to an increasing body of evidence, macular degeneration may be induced. Despite this, SR exposure risk is currently undervalued, if not neglected, as an occupational risk factor for outdoor workers. SR exposure is influenced by various environmental and individual factors, and occupation is one of the most relevant. For a better understanding of this risk and for the development of more effective prevention strategies, one of the main problems is the lack of available and adequate methods to estimate SR worker exposure, especially long-term exposure. The main aims of this review were to provide a comprehensive overview of SR exposure risk of outdoor workers, including the UV exposure levels and the main methods recently proposed for short-term and cumulative exposure, and to provide an update of knowledge on the main adverse eye and skin effects. Finally, we also outline here preventive interventions to reduce occupational risk.
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Affiliation(s)
- Alberto Modenese
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena & Reggio Emilia, 41124 Modena, Italy.
| | - Leena Korpinen
- Clinical Physiology and Neurophysiology Unit, The North Karelia Central Hospital, 80210 Joensuu, Finland.
| | - Fabriziomaria Gobba
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena & Reggio Emilia, 41124 Modena, Italy.
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115
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Modenese A, Gobba F. Macular degeneration and occupational risk factors: a systematic review. Int Arch Occup Environ Health 2018; 92:1-11. [PMID: 30191305 PMCID: PMC6323067 DOI: 10.1007/s00420-018-1355-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 09/04/2018] [Indexed: 01/08/2023]
Abstract
Purpose Macular degeneration is a multi-factorial disease, leading cause of blindness for people over 50 years old in developed countries. To date, the knowledge on possible occupational factors involved in the development of the disease is scant. Method We performed a systematic scientific literature search on the association between macular degeneration and occupational risk factors searching the MedLine and Scopus databases. Results We examined 158 articles and, according to the inclusion criteria, 13 peer-reviewed studies evaluating occupational risk factors for macular degeneration or reporting the frequency of the disease in specific groups of workers were included in the review. Ten on thirteen articles evaluated the presence of macular degeneration in workers exposed to solar radiation. Only one study found that non-specific history of occupational chemical exposure was associated with the disease. Two studies showed an association between macular degeneration and the general category of “blue-collar” workers, but they did not identify the specific risk factors involved. Conclusions To date few studies have examined occupational risk factors for macular degeneration. Nevertheless, available data indicate that long-term occupational solar radiation exposure, in particular for its blue-light component, is associated with macular degeneration in outdoor workers. Electronic supplementary material The online version of this article (10.1007/s00420-018-1355-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Alberto Modenese
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Via G. Campi 287, 41125, Modena, Italy.
| | - Fabriziomaria Gobba
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Via G. Campi 287, 41125, Modena, Italy
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116
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Atienzar-Aroca S, Serrano-Heras G, Freire Valls A, Ruiz de Almodovar C, Muriach M, Barcia JM, Garcia-Verdugo JM, Romero FJ, Sancho-Pelluz J. Role of retinal pigment epithelium-derived exosomes and autophagy in new blood vessel formation. J Cell Mol Med 2018; 22:5244-5256. [PMID: 30133118 PMCID: PMC6201377 DOI: 10.1111/jcmm.13730] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2017] [Accepted: 05/22/2018] [Indexed: 12/20/2022] Open
Abstract
Autophagy and exosome secretion play important roles in a variety of physiological and disease states, including the development of age‐related macular degeneration. Previous studies have demonstrated that these cellular mechanisms share common pathways of activation. Low oxidative damage in ARPE‐19 cells, alters both autophagy and exosome biogenesis. Moreover, oxidative stress modifies the protein and genetic cargo of exosomes, possibly affecting the fate of surrounding cells. In order to understand the connection between these two mechanisms and their impact on angiogenesis, stressed ARPE‐19 cells were treated with a siRNA‐targeting Atg7, a key protein for the formation of autophagosomes. Subsequently, we observed the formation of multivesicular bodies and the release of exosomes. Released exosomes contained VEGFR2 as part of their cargo. This receptor for VEGF—which is critical for the development of new blood vessels—was higher in exosome populations released from stressed ARPE‐19. While stressed exosomes enhanced tube formation, exosomes became ineffective after silencing VEGFR2 in ARPE‐19 cells and were, consequently, unable to influence angiogenesis. Moreover, vessel sprouting in the presence of stressed exosomes seems to follow a VEGF‐independent pathway. We propose that abnormal vessel growth correlates with VEGFR2‐expressing exosomes release from stressed ARPE‐19 cells, and is directly linked to autophagy.
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Affiliation(s)
| | - Gemma Serrano-Heras
- Experimental Research Unit, General University Hospital of Albacete, Albacete, Spain
| | - Aida Freire Valls
- Heidelberg Biochemie-Zentrum (BZH), University of Heidelberg, Heidelberg, Germany
| | | | - Maria Muriach
- Unidad predepartamental de Medicina, Universitat Jaume I, Castellón de la Plana, Spain
| | - Jorge M Barcia
- School of Medicine, Catholic University of Valencia, Valencia, Spain
| | | | - Francisco J Romero
- Faculty of Health Sciences, Universidad Europea de Valencia, Valencia, Spain
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117
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Panagiotou N, Neytchev O, Selman C, Shiels PG. Extracellular Vesicles, Ageing, and Therapeutic Interventions. Cells 2018; 7:cells7080110. [PMID: 30126173 PMCID: PMC6115766 DOI: 10.3390/cells7080110] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 08/13/2018] [Accepted: 08/16/2018] [Indexed: 02/07/2023] Open
Abstract
A more comprehensive understanding of the human ageing process is required to help mitigate the increasing burden of age-related morbidities in a rapidly growing global demographic of elderly individuals. One exciting novel strategy that has emerged to intervene involves the use of extracellular vesicles to engender tissue regeneration. Specifically, this employs their molecular payloads to confer changes in the epigenetic landscape of ageing cells and ameliorate the loss of functional capacity. Understanding the biology of extracellular vesicles and the specific roles they play during normative ageing will allow for the development of novel cell-free therapeutic interventions. Hence, the purpose of this review is to summarise the current understanding of the mechanisms that drive ageing, critically explore how extracellular vesicles affect ageing processes and discuss their therapeutic potential to mitigate the effects of age-associated morbidities and improve the human health span.
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Affiliation(s)
- Nikolaos Panagiotou
- Wolfson Wohl Cancer Research Centre, College of Medical, Veterinary & Life Sciences, Institute of Cancer Sciences, University of Glasgow, Glasgow G61 1QH, UK.
| | - Ognian Neytchev
- Wolfson Wohl Cancer Research Centre, College of Medical, Veterinary & Life Sciences, Institute of Cancer Sciences, University of Glasgow, Glasgow G61 1QH, UK.
| | - Colin Selman
- College of Medical, Veterinary & Life Sciences, Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Graham Kerr, Glasgow G12 8QQ, UK.
| | - Paul G Shiels
- Wolfson Wohl Cancer Research Centre, College of Medical, Veterinary & Life Sciences, Institute of Cancer Sciences, University of Glasgow, Glasgow G61 1QH, UK.
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118
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Hyttinen JMT, Viiri J, Kaarniranta K, Błasiak J. Mitochondrial quality control in AMD: does mitophagy play a pivotal role? Cell Mol Life Sci 2018; 75:2991-3008. [PMID: 29777261 PMCID: PMC11105454 DOI: 10.1007/s00018-018-2843-7] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 04/25/2018] [Accepted: 05/16/2018] [Indexed: 01/05/2023]
Abstract
Age-related macular degeneration (AMD) is the predominant cause of visual loss in old people in the developed world, whose incidence is increasing. This disease is caused by the decrease in macular function, due to the degeneration of retinal pigment epithelium (RPE) cells. The aged retina is characterised by increased levels of reactive oxygen species (ROS), impaired autophagy, and DNA damage that are linked to AMD pathogenesis. Mitophagy, a mitochondria-specific type of autophagy, is an essential part of mitochondrial quality control, the collective mechanism responsible for this organelle's homeostasis. The abundance of ROS, DNA damage, and the excessive energy consumption in the ageing retina all contribute to the degeneration of RPE cells and their mitochondria. We discuss the role of mitophagy in the cell and argue that its impairment may play a role in AMD pathogenesis. Thus, mitophagy as a potential therapeutic target in AMD and other degenerative diseases is as well explored.
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Affiliation(s)
- Juha M T Hyttinen
- Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, P.O. Box 1627, 70211, Kuopio, Finland.
| | - Johanna Viiri
- Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, P.O. Box 1627, 70211, Kuopio, Finland
| | - Kai Kaarniranta
- Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, P.O. Box 1627, 70211, Kuopio, Finland
- Department of Ophthalmology, Kuopio University Hospital, P.O. Box 100, 70029 KYS, Kuopio, Finland
| | - Janusz Błasiak
- Department of Molecular Genetics, University of Łódź, Pomorska 141/143, 90-236, Łódź, Poland
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119
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Lin YC, Horng LY, Sung HC, Wu RT. Sodium Iodate Disrupted the Mitochondrial-Lysosomal Axis in Cultured Retinal Pigment Epithelial Cells. J Ocul Pharmacol Ther 2018; 34:500-511. [PMID: 30020815 DOI: 10.1089/jop.2017.0073] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
PURPOSE Low doses of sodium iodate (NaIO3) impair visual function in experimental animals with selective damage to retinal pigment epithelium (RPE) and serve as a useful model to study diseases caused by RPE degeneration. Mitochondrial dysfunction and defective autophagy have been suggested to play important roles in normal aging as well as many neurodegenerative diseases. In this study, we examined whether NaIO3 treatment disrupted the mitochondrial-lysosomal axis in cultured RPE. METHODS The human RPE cell line, ARPE-19, was treated with low concentrations (≤500 μM) of NaIO3. The expression of proteins involved in the autophagic pathway and mitochondrial biogenesis was examined with Western blot. Intracellular acidic compartments and lipofuscinogenesis were evaluated by acridine orange staining and autofluorescence, respectively. Mitochondrial mass, mitochondrial membrane potential (MMP), and mitochondrial function were quantified by MitoTracker Green staining, tetramethylrhodamine methyl ester staining, and the MTT assay, respectively. Phagocytosis and the degradation of photoreceptor outer segments (POS) were assessed by fluorescence-based approaches and Western blot against rhodopsin. RESULTS Treatment with low concentrations of NaIO3 decreased cellular acidity, blocked autophagic flux, and resulted in increased lipofuscinogenesis in ARPE-19 cells. Despite increases in protein levels of Sirtuin 1 and PGC-1α, mitochondrial function was compromised, and this decrease was attributed to disrupted MMP. POS phagocytic activities decreased by 60% in NaIO3-treated cells, and the degradation of ingested POS was also impaired. Pretreatment and cotreatment with rapamycin partially rescued NaIO3-induced RPE dysfunction. CONCLUSIONS Low concentrations of NaIO3 disrupted the mitochondrial-lysosomal axis in RPE and led to impaired phagocytic activities and degradation capacities.
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Affiliation(s)
- Ying-Cheng Lin
- 1 Institute of Biopharmaceutical Sciences, School of Pharmaceutical Sciences, National Yang-Ming University , Taipei, Taiwan .,2 Department of Ophthalmology, Yang-Ming branch, Taipei City Hospital , Taipei, Taiwan
| | - Lin-Yea Horng
- 1 Institute of Biopharmaceutical Sciences, School of Pharmaceutical Sciences, National Yang-Ming University , Taipei, Taiwan .,3 Research Center for Drug Discovery, National Yang-Ming University , Taipei, Taiwan
| | - Hui-Ching Sung
- 3 Research Center for Drug Discovery, National Yang-Ming University , Taipei, Taiwan
| | - Rong-Tsun Wu
- 1 Institute of Biopharmaceutical Sciences, School of Pharmaceutical Sciences, National Yang-Ming University , Taipei, Taiwan .,3 Research Center for Drug Discovery, National Yang-Ming University , Taipei, Taiwan .,4 Graduate Institute of Natural Products, College of Pharmacy, Kaohsiung Medical University , Kaohsiung, Taiwan
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120
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Osman AHK, Shintani M. Autophagy in normal tissues of camel (Camelus dromedarius) with focus on immunoexpression of LC3 and LC3B. Biotech Histochem 2018; 93:557-564. [PMID: 29969923 DOI: 10.1080/10520295.2018.1470728] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
Autophagy is a highly regulated intracellular pathway for degradation and recycling of cytoplasmic protein aggregates and entire organelles. The autophagic pathway is stimulated by nutrient starvation, which prompted us to study the desert camel. Various organs of the camel undergo ecological and physiological stress due to food and water deprivation, dehydration and long exposure to solar radiation. We investigated the immunohistochemical expression of specific biomarkers of autophagy under normal conditions as a baseline for later work on stressed individuals. The autophagy-specific biomarkers, microtubule-associated protein1 light chain 3 (LC3), and its cleaved variant, LC3B, were strongly expressed in the cytosol of all tissues examined. The cytosolic immunoreactivity of LC3 was relatively weak, diffuse and vacuolar, while that of LC3B was stronger, punctate and at lower levels. LC3 appears to be associated with the autophagosomal membranes, either free or lysosome-bounded. LC3B is specific for the autophagosome-lysosome complexes and their degraded, granular contents. Autophagy was strongly expressed in CNS neurons and intestinal neural elements, which suggests a protective function for the nervous system. Autophagic markers also were seen in deformed immune-competent cells with fragmented nuclei in lymph nodes, spleen and gut-associated lymphoid tissue (GALT), which suggests a "suicidal" activity of eliminating unneeded cells. Autophagy, as measured by LC3 and LC3B expression, may participate in a general regulatory mechanism in tissues of the desert camel.
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Affiliation(s)
- Abdel-Hamid K Osman
- a Department of Cytology and Histology, Faculty of Veterinary Medicine , Suez Canal University , Ismailia , Egypt
| | - Michiko Shintani
- b Laboratory of Pathology, Division of Medical Biosciences , kobe University Graduate School of Health Sciences , Kobe , Japan
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121
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Khan K, Tewari S, Rastogi M, Agarwal GR, Mishra SP, Husain N. Quantitative Extra Long PCR to Detect DNA Lesions in Patients Exposed to Low Doses of Diagnostic Radiation. Asian Pac J Cancer Prev 2018; 19:1367-1373. [PMID: 29802702 PMCID: PMC6031809 DOI: 10.22034/apjcp.2018.19.5.1367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 04/11/2018] [Indexed: 11/28/2022] Open
Abstract
Background: Radiation causes oxidative lesions and strand breaks in DNA of exposed cells. Extended length PCR is a reliable method for assessing DNA damage. Longer DNA strands with DNA damage are difficult to amplify compared to smaller DNA strands by PCR. The present study was aimed to evaluate DNA damage caused by ionising radiation exposure in therapeutic and diagnostic medicine. Materials and Methods: The study group comprised 50 cases with low dose single exposure (LDS), low dose multiple exposure (LDM) and low dose angiography (LDA) which were compared with 25 high dose controls (HDC) and 25 controls with no exposure (NEC). Blood samples were collected within 1 hour of radiation exposure. DNA was isolated using a kit based protocol, 50 ng aliquots of DNA were used to amplify a long 13kbp DNA fragment of the β-actin gene by conventional PCR and band intensity was then quantified. Relative amplification was calculated and damage was expressed in terms of lesions per kilobase (kbp) by assuming a Poisson distribution. Result: Relative amplification was found to be 1.0, 0.87, 0.86, 0.72 and 0.69 with NEC, LDS, LDM, LDA and HDC groups, respectively. Cases undergoing angiography as well as high dose controls had high values, compared to NEC. The lesions/kbp calculated for LDS was 0.13, for LDM 0.15, for LDA 0.32 and for HDC 0.37 suggesting a linear increase in quantity with increasing radiation dose. Conclusion: DNA damage, even at low doses of radiation can be assessed by quantitative extra long PCR.
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Affiliation(s)
- Kainat Khan
- Department of Pathology, Dr. Ram Manohar Lohia Institute of Medical Sciences, Lucknow, India.
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122
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Zhao Y, Weber SR, Lease J, Russo M, Siedlecki CA, Xu LC, Chen H, Wang W, Ford M, Simó R, Sundstrom JM. Liquid Biopsy of Vitreous Reveals an Abundant Vesicle Population Consistent With the Size and Morphology of Exosomes. Transl Vis Sci Technol 2018; 7:6. [PMID: 29774170 PMCID: PMC5954840 DOI: 10.1167/tvst.7.3.6] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 03/03/2018] [Indexed: 12/21/2022] Open
Abstract
Purpose To investigate the molecular components of the vitreous in order to better understand retinal physiology and disease. Methods Vitreous was acquired from patients undergoing vitrectomy for macular hole and/or epiretinal membrane, postmortem donors, and C57BL/6J mice. Unbiased proteomic analysis was performed via electrospray ionization tandem mass spectrometry (MS/MS). Gene ontology analysis was performed and results were confirmed with transmission electron microscopy, atomic force microscopy, and nanoparticle tracking analysis (NTA). Results Proteomic analysis of vitreous obtained prior to vitrectomy identified a total of 1121 unique proteins. Gene ontology analysis revealed that 62.6% of the vitreous proteins were associated with the gene ontology term “extracellular exosome.” Ultrastructural analyses, Western blot, and NTA confirmed the presence of an abundant population of vesicles consistent with the size and morphology of exosomes in human vitreous. The concentrations of vitreous vesicles in vitrectomy patients, postmortem donors, and mice were 1.3, 35, and 9 billion/mL, respectively. Conclusions Overall, these data strongly suggest that information-rich exosomes are a major constituent of the vitreous. The abundance of these vesicles and the presence of retinal proteins imply a dynamic interaction between the vitreous and retina. Future studies will be required to identify the cellular origin of vitreal exosomes as well as to assess the potential role of these vesicles in retinal disease and treatment. Translational Relevance The identification of vitreous exosomes lays the groundwork for a transformed understanding of pathophysiology and treatment mechanisms in retinal disease, and further validates the use of vitreous as a proximal biofluid of the retina.
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Affiliation(s)
- Yuanjun Zhao
- Department of Ophthalmology, Penn State Hershey Medical Center, Hershey, PA, USA
| | - Sarah R Weber
- Department of Ophthalmology, Penn State Hershey Medical Center, Hershey, PA, USA.,Kellogg Eye Center, University of Michigan, Ann Arbor, MI, USA
| | - Joshua Lease
- Research Informatics, Penn State Hershey Medical Center, Hershey, PA, USA
| | - Mariano Russo
- Department of Biochemistry and Molecular Biology, Penn State Hershey Medical Center, Hershey, PA, USA
| | - Christopher A Siedlecki
- Department of Surgery, Penn State Hershey Medical Center, Hershey, PA, USA.,Department of Biomedical Engineering, Penn State Hershey Medical Center, Hershey, PA, USA
| | - Li-Chong Xu
- Department of Surgery, Penn State Hershey Medical Center, Hershey, PA, USA
| | - Han Chen
- Microscopy Imaging Facility, Penn State Hershey Medical Center, Hershey, PA, USA
| | - Weiwei Wang
- Department of Ophthalmology, Penn State Hershey Medical Center, Hershey, PA, USA
| | | | - Rafael Simó
- Institut de Recerca Hospital Universitari Vall d'Hebron (VHIR) and CIBERDEM (Instituto de Salud Carlos III), Barcelona, Spain
| | - Jeffrey M Sundstrom
- Department of Ophthalmology, Penn State Hershey Medical Center, Hershey, PA, USA.,Kellogg Eye Center, University of Michigan, Ann Arbor, MI, USA
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Chen CL, Chen YH, Liang CM, Tai MC, Lu DW, Chen JT. Glucosamine-Induced Autophagy through AMPK⁻mTOR Pathway Attenuates Lipofuscin-Like Autofluorescence in Human Retinal Pigment Epithelial Cells In Vitro. Int J Mol Sci 2018; 19:ijms19051416. [PMID: 29747425 PMCID: PMC5983587 DOI: 10.3390/ijms19051416] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 04/20/2018] [Accepted: 05/08/2018] [Indexed: 12/02/2022] Open
Abstract
Age-related macular degeneration (AMD) is a vision-threatening age-associated disease. The retinal pigment epithelial (RPE) cells phagocytose and digest photoreceptor outer segment (POS). Incomplete digestion of POS leads to lipofuscin accumulation, which contributes to the pathology of the AMD. Autophagy could help reduce the amount of lipofuscin accumulation. In the present study, we evaluated the effects of glucosamine (GlcN), a natural supplement, on the induction of autophagy and POS-derived lipofuscin-like autofluorescence (LLAF) in ARPE-19 cells in vitro, and investigated the potential molecular pathway involved. Our results revealed that GlcN had no effect on phagocytosis of POS at the lower doses. GlcN treatment induced autophagy in cells. GlcN decreased the LLAF in native POS-treated cells, whereas malondialdehyde or 4-hydroxynonenal-modified POS attenuated this effect. 3-Methyladenine inhibited GlcN-induced autophagy and attenuated the effect of GlcN on the decrease of the native POS-derived LLAF. Furthermore, GlcN induced the phosphorylation of AMP-activated protein kinase (AMPK) and inhibited the phosphorylation of mammalian target of rapamycin (mTOR), whereas Compound C inhibited these effects of GlcN. Altogether, these results suggest that GlcN decreased the native POS-derived LLAF through induction of autophagy, at least in part, by the AMPK–mTOR pathway. This mechanism has potential for the preventive treatment of lipofuscin-related retinal degeneration such as AMD.
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Affiliation(s)
- Ching-Long Chen
- Department of Ophthalmology, Tri-Service General Hospital, National Defense Medical Center, 325 Cheng-Kung Road, Section 2, Taipei 114, Taiwan.
| | - Yi-Hao Chen
- Department of Ophthalmology, Tri-Service General Hospital, National Defense Medical Center, 325 Cheng-Kung Road, Section 2, Taipei 114, Taiwan.
| | - Chang-Min Liang
- Department of Ophthalmology, Tri-Service General Hospital, National Defense Medical Center, 325 Cheng-Kung Road, Section 2, Taipei 114, Taiwan.
| | - Ming-Cheng Tai
- Department of Ophthalmology, Tri-Service General Hospital, National Defense Medical Center, 325 Cheng-Kung Road, Section 2, Taipei 114, Taiwan.
| | - Da-Wen Lu
- Department of Ophthalmology, Tri-Service General Hospital, National Defense Medical Center, 325 Cheng-Kung Road, Section 2, Taipei 114, Taiwan.
| | - Jiann-Torng Chen
- Department of Ophthalmology, Tri-Service General Hospital, National Defense Medical Center, 325 Cheng-Kung Road, Section 2, Taipei 114, Taiwan.
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124
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Paper-Based Microfluidic Platforms for Understanding the Role of Exosomes in the Pathogenesis of Major Blindness-Threatening Diseases. NANOMATERIALS 2018; 8:nano8050310. [PMID: 29738436 PMCID: PMC5977324 DOI: 10.3390/nano8050310] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 04/28/2018] [Accepted: 05/07/2018] [Indexed: 12/16/2022]
Abstract
Emerging roles of exosomes in the pathogenesis of major blindness-threatening diseases, such as age-related macular degeneration, glaucoma, and corneal dystrophy, were discovered by aqueous humor analysis. A new diagnostic method using cellulose-based devices and microfluidic chip techniques for the isolation of exosomes from aqueous humor is less cumbersome and saves time. This method will enable more investigations for aqueous humor analysis in the future.
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125
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Shah N, Ishii M, Brandon C, Ablonczy Z, Cai J, Liu Y, Chou CJ, Rohrer B. Extracellular vesicle-mediated long-range communication in stressed retinal pigment epithelial cell monolayers. Biochim Biophys Acta Mol Basis Dis 2018; 1864:2610-2622. [PMID: 29684588 DOI: 10.1016/j.bbadis.2018.04.016] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 04/03/2018] [Accepted: 04/17/2018] [Indexed: 02/06/2023]
Abstract
Retinal pigment epithelium (RPE) alterations in age-related macular degeneration occur in patches, potentially involving long-distance communication between damaged and healthy areas. Communication along the epithelium might be mediated by extracellular vesicles (EVs). To test this hypothesis, EVs were collected from supernatants of polarized ARPE-19 and primary porcine RPE monolayers for functional and biochemical assays. EVs from oxidatively stressed donor cells reduced barrier function in recipient RPE monolayers when compared to control EVs. The effect on barrier function was dependent on EV uptake, which occurred rapidly with EVs from oxidatively stressed donor cells. Mass spectrometry-based proteomic analysis of EVs identified HDAC6, which is known to reduce tight junction stability. Activity assays confirmed the presence of HDAC6 in EVs, and EV transfer assays using HDAC6 inhibitors confirmed its effect in monolayers. These findings demonstrate that EVs can communicate stress messages to healthy RPE cells, potentially contributing to RPE dysfunction.
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Affiliation(s)
- Navjot Shah
- Department of Ophthalmology, Medical University of South Carolina, Charleston, SC 29425, United States; Ralph H. Johnson VA Medical Center, Charleston, SC 29401, United States
| | - Masakii Ishii
- Department of Ophthalmology, Medical University of South Carolina, Charleston, SC 29425, United States; Ralph H. Johnson VA Medical Center, Charleston, SC 29401, United States
| | - Carlene Brandon
- Department of Ophthalmology, Medical University of South Carolina, Charleston, SC 29425, United States
| | - Zsolt Ablonczy
- Department of Ophthalmology, Medical University of South Carolina, Charleston, SC 29425, United States
| | - Jingwen Cai
- Cellular Biology & Anatomy, Augusta University, Augusta, GA 30912, United States
| | - Yutao Liu
- Cellular Biology & Anatomy, Augusta University, Augusta, GA 30912, United States
| | - C James Chou
- Department of Drug Discovery, Medical University of South Carolina, Charleston, SC 29425, United States
| | - Bärbel Rohrer
- Department of Ophthalmology, Medical University of South Carolina, Charleston, SC 29425, United States; Ralph H. Johnson VA Medical Center, Charleston, SC 29401, United States; Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29425, United States.
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126
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Karasu E, Eisenhardt SU, Harant J, Huber-Lang M. Extracellular Vesicles: Packages Sent With Complement. Front Immunol 2018; 9:721. [PMID: 29696020 PMCID: PMC5904200 DOI: 10.3389/fimmu.2018.00721] [Citation(s) in RCA: 94] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 03/23/2018] [Indexed: 12/20/2022] Open
Abstract
Cells communicate with other cells in their microenvironment by transferring lipids, peptides, RNA, and sugars in extracellular vesicles (EVs), thereby also influencing recipient cell functions. Several studies indicate that these vesicles are involved in a variety of critical cellular processes including immune, metabolic, and coagulatory responses and are thereby associated with several inflammatory diseases. Furthermore, EVs also possess anti-inflammatory properties and contribute to immune regulation, thus encouraging an emerging interest in investigating and clarifying mechanistic links between EVs and innate immunity. Current studies indicate complex interactions of the complement system with EVs, with a dramatic influence on local and systemic inflammation. During inflammatory conditions with highly activated complement, including after severe tissue trauma and during sepsis, elevated numbers of EVs were found in the circulation of patients. There is increasing evidence that these shed vesicles contain key complement factors as well as complement regulators on their surface, affecting inflammation and the course of disease. Taken together, interaction of EVs regulates complement activity and contributes to the pro- and anti-inflammatory immune balance. However, the molecular mechanisms behind this interaction remain elusive and require further investigation. The aim of this review is to summarize the limited current knowledge on the crosstalk between complement and EVs. A further aspect is the clinical relevance of EVs with an emphasis on their capacity as potential therapeutic vehicles in the field of translational medicine.
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Affiliation(s)
- Ebru Karasu
- Institute of Clinical and Experimental Trauma-Immunology, Universitätsklinikum Ulm, Ulm, Germany
| | - Steffen U Eisenhardt
- Division of Reconstructive Microsurgery, Department of Plastic and Hand Surgery, University of Freiburg Faculty of Medicine, University of Freiburg Medical Centre, Freiburg, Germany
| | - Julia Harant
- Institute of Clinical and Experimental Trauma-Immunology, Universitätsklinikum Ulm, Ulm, Germany
| | - Markus Huber-Lang
- Institute of Clinical and Experimental Trauma-Immunology, Universitätsklinikum Ulm, Ulm, Germany
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127
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Kivinen N. The role of autophagy in age-related macular degeneration. Acta Ophthalmol 2018; 96 Suppl A110:1-50. [PMID: 29633521 DOI: 10.1111/aos.13753] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Niko Kivinen
- Department of Ophthalmology; University of Eastern Finland; Kuopio Finland
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128
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Over-expression of CNTF in bone marrow mesenchymal stem cells protects RPE cells from short-wavelength, blue-light injury. In Vitro Cell Dev Biol Anim 2018; 54:355-365. [PMID: 29564604 DOI: 10.1007/s11626-018-0243-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Accepted: 03/13/2018] [Indexed: 12/20/2022]
Abstract
Increasing evidence has demonstrated that excessive blue-light (BL) with high photochemical energy and phototoxicity could induce apoptosis in retinal pigment epithelium (RPE) cells. RPE apoptosis leads to retina damage and further aggravate age-related macular degeneration (ARMD). Because of their neuroprotective, plasticity, and immunomodulatory ability, bone marrow mesenchymal stem cells (BMSCs) are recognized for retinal neuroprotection. RPE cells possess ciliary neurotrophic factor (CNTF) receptor complexes and can respond to CNTF; hence, we investigated the effects of BMSCs over-expressing CNTF on BL-injured RPE cells. BL-injured RPE cells were co-cultured with CNTF-BMSCs and GFP-BMSCs for 24 and 48 h. Superoxide dismutase and malondialdehyde assays were conducted to examine the effects of CNTF-BMSCs on the oxidative stress of RPE cells. VEGF protein secretion by RPE was determined by ELISA, and western blotting analysis was used to determine apoptotic protein expression and autophagic flux. Immunofluorescence was used to demonstrate the relationship between autophagy and apoptosis. We found that CNTF-BMSCs enhanced antioxidant capacity, decreased VEGF secretion, promoted autophagic flux, and inhibited apoptosis in BL-injured RPE cells, compared to GFP-BMSCs. Our findings suggest that CNTF over-expression enhances the protective effects of BMSCs on RPE cells, thus indicating subretinal-transplantation of CNTF-BMSCs may be a promising therapy for BL-injured retina.
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129
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Keeling E, Lotery AJ, Tumbarello DA, Ratnayaka JA. Impaired Cargo Clearance in the Retinal Pigment Epithelium (RPE) Underlies Irreversible Blinding Diseases. Cells 2018; 7:E16. [PMID: 29473871 PMCID: PMC5850104 DOI: 10.3390/cells7020016] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2018] [Revised: 02/20/2018] [Accepted: 02/22/2018] [Indexed: 01/09/2023] Open
Abstract
Chronic degeneration of the Retinal Pigment Epithelium (RPE) is a precursor to pathological changes in the outer retina. The RPE monolayer, which lies beneath the neuroretina, daily internalises and digests large volumes of spent photoreceptor outer segments. Impaired cargo handling and processing in the endocytic/phagosome and autophagy pathways lead to the accumulation of lipofuscin and pyridinium bis-retinoid A2E aggregates and chemically modified compounds such as malondialdehyde and 4-hydroxynonenal within RPE. These contribute to increased proteolytic and oxidative stress, resulting in irreversible damage to post-mitotic RPE cells and development of blinding conditions such as age-related macular degeneration, Stargardt disease and choroideremia. Here, we review how impaired cargo handling in the RPE results in their dysfunction, discuss new findings from our laboratory and consider how newly discovered roles for lysosomes and the autophagy pathway could provide insights into retinopathies. Studies of these dynamic, molecular events have also been spurred on by recent advances in optics and imaging technology. Mechanisms underpinning lysosomal impairment in other degenerative conditions including storage disorders, α-synuclein pathologies and Alzheimer's disease are also discussed. Collectively, these findings help transcend conventional understanding of these intracellular compartments as simple waste disposal bags to bring about a paradigm shift in the way lysosomes are perceived.
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Affiliation(s)
- Eloise Keeling
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, MP806, Tremona Road, Southampton SO16 6YD, UK.
| | - Andrew J Lotery
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, MP806, Tremona Road, Southampton SO16 6YD, UK.
- Eye Unit, University Hospital Southampton NHS Foundation Trust, Southampton SO16 6YD, UK.
| | - David A Tumbarello
- Biological Sciences, Faculty of Natural & Environmental Sciences, Life Science Building 85, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK.
| | - J Arjuna Ratnayaka
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, MP806, Tremona Road, Southampton SO16 6YD, UK.
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130
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Epigenetic modifications in hyperhomocysteinemia: potential role in diabetic retinopathy and age-related macular degeneration. Oncotarget 2018; 9:12562-12590. [PMID: 29560091 PMCID: PMC5849155 DOI: 10.18632/oncotarget.24333] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2017] [Accepted: 01/24/2018] [Indexed: 02/03/2023] Open
Abstract
To study Hyperhomocysteinemia (HHcy)-induced epigenetic modifications as potential mechanisms of blood retinal barrier (BRB) dysfunction, retinas isolated from three- week-old mice with elevated level of Homocysteine (Hcy) due to lack of the enzyme cystathionine β-synthase (cbs-/- , cbs+/- and cbs+/+ ), human retinal endothelial cells (HRECs), and human retinal pigmented epithelial cells (ARPE-19) treated with or without Hcy were evaluated for (1) histone deacetylases (HDAC), (2) DNA methylation (DNMT), and (3) miRNA analysis. Differentially expressed miRNAs in mice with HHcy were further compared with miRNA analysis of diabetic mice retinas (STZ) and miRNAs within the exosomes released from Hcy-treated RPEs. Differentially expressed miRNAs were further evaluated for predicted target genes and associated pathways using Ingenuity Pathway Analysis. HHcy significantly increased HDAC and DNMT activity in HRECs, ARPE-19, and cbs mice retinas, whereas inhibition of HDAC and DNMT decreased Hcy-induced BRB dysfunction. MiRNA profiling detected 127 miRNAs in cbs+/- and 39 miRNAs in cbs-/- mice retinas, which were significantly differentially expressed compared to cbs+/+ . MiRNA pathway analysis showed their involvement in HDAC and DNMT activation, endoplasmic reticulum (ER), and oxidative stresses, inflammation, hypoxia, and angiogenesis pathways. Hcy-induced epigenetic modifications may be involved in retinopathies associated with HHcy, such as age-related macular degeneration and diabetic retinopathy.
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131
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Klingeborn M, Stamer WD, Bowes Rickman C. Polarized Exosome Release from the Retinal Pigmented Epithelium. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1074:539-544. [PMID: 29721985 DOI: 10.1007/978-3-319-75402-4_65] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The retinal pigmented epithelium (RPE) forms the outer blood-retinal barrier and provides nutrients and recycling of visual pigment to the photoreceptors, among many other functions. The RPE is also a key site of pathophysiological changes in age-related macular degeneration, making it an important focus of study in both visual health and disease. Exosomes are nanometer-sized vesicles that are released by cells in a controlled fashion and mediate a range of extra- and intercellular activities. Some key exosome actions include cell-cell communication, immune modulation, extracellular matrix turnover, stem cell division/differentiation, neovascularization, and cellular waste removal. While much is known about their role in cancer and cardiovascular disease, exosome function in the many specialized tissues of the eye is just beginning to undergo rigorous study. Here we review current knowledge of the functions and roles of exosomes and other small extracellular vesicles released from the RPE. In particular, we discuss the potential role and importance of polarized exosome release from the RPE.
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Affiliation(s)
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, NC, USA
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Catherine Bowes Rickman
- Department of Ophthalmology, Duke University, Durham, NC, USA
- Department of Cell Biology, Duke University, Durham, NC, USA
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132
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Crooke A, Huete-Toral F, Colligris B, Pintor J. The role and therapeutic potential of melatonin in age-related ocular diseases. J Pineal Res 2017; 63. [PMID: 28658514 DOI: 10.1111/jpi.12430] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 06/23/2017] [Indexed: 12/20/2022]
Abstract
The eye is continuously exposed to solar UV radiation and pollutants, making it prone to oxidative attacks. In fact, oxidative damage is a major cause of age-related ocular diseases including cataract, glaucoma, age-related macular degeneration, and diabetic retinopathy. As the nature of lens cells, trabecular meshwork cells, retinal ganglion cells, retinal pigment epithelial cells, and photoreceptors is postmitotic, autophagy plays a critical role in their cellular homeostasis. In age-related ocular diseases, this process is impaired, and thus, oxidative damage becomes irreversible. Other conditions such as low-grade chronic inflammation and angiogenesis also contribute to the development of retinal diseases (glaucoma, age-related macular degeneration and diabetic retinopathy). As melatonin is known to have remarkable qualities such as antioxidant/antinitridergic, mitochondrial protector, autophagy modulator, anti-inflammatory, and anti-angiogenic, it can represent a powerful tool to counteract all these diseases. The present review analyzes the role and therapeutic potential of melatonin in age-related ocular diseases, focusing on nitro-oxidative stress, autophagy, inflammation, and angiogenesis mechanisms.
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Affiliation(s)
- Almudena Crooke
- Department of Biochemistry and Molecular Biology IV, Group Ocupharm, Faculty of Optics and Optometry, Universidad Complutense de Madrid, Madrid, Spain
| | - Fernando Huete-Toral
- Department of Biochemistry and Molecular Biology IV, Group Ocupharm, Faculty of Optics and Optometry, Universidad Complutense de Madrid, Madrid, Spain
| | - Basilio Colligris
- Department of Biochemistry and Molecular Biology IV, Group Ocupharm, Faculty of Optics and Optometry, Universidad Complutense de Madrid, Madrid, Spain
| | - Jesús Pintor
- Department of Biochemistry and Molecular Biology IV, Group Ocupharm, Faculty of Optics and Optometry, Universidad Complutense de Madrid, Madrid, Spain
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133
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Klingeborn M, Dismuke WM, Skiba NP, Kelly U, Stamer WD, Bowes Rickman C. Directional Exosome Proteomes Reflect Polarity-Specific Functions in Retinal Pigmented Epithelium Monolayers. Sci Rep 2017; 7:4901. [PMID: 28687758 PMCID: PMC5501811 DOI: 10.1038/s41598-017-05102-9] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 05/30/2017] [Indexed: 01/09/2023] Open
Abstract
The retinal pigmented epithelium (RPE) forms the outer blood-retinal barrier in the eye and its polarity is responsible for directional secretion and uptake of proteins, lipoprotein particles and extracellular vesicles (EVs). Such a secretional division dictates directed interactions between the systemic circulation (basolateral) and the retina (apical). Our goal is to define the polarized proteomes and physical characteristics of EVs released from the RPE. Primary cultures of porcine RPE cells were differentiated into polarized RPE monolayers on permeable supports. EVs were isolated from media bathing either apical or basolateral RPE surfaces, and two subpopulations of small EVs including exosomes, and dense EVs, were purified and processed for proteomic profiling. In parallel, EV size distribution and concentration were determined. Using protein correlation profiling mass spectrometry, a total of 631 proteins were identified in exosome preparations, 299 of which were uniquely released apically, and 94 uniquely released basolaterally. Selected proteins were validated by Western blot. The proteomes of these exosome and dense EVs preparations suggest that epithelial polarity impacts directional release. These data serve as a foundation for comparative studies aimed at elucidating the role of exosomes in the molecular pathophysiology of retinal diseases and help identify potential therapeutic targets and biomarkers.
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Affiliation(s)
- Mikael Klingeborn
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, 27710, USA.
| | - W Michael Dismuke
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, 27710, USA
| | - Nikolai P Skiba
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, 27710, USA
| | - Una Kelly
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, 27710, USA
| | - W Daniel Stamer
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, 27710, USA.,Department of Biomedical Engineering, Duke University, Durham, NC, 27710, USA
| | - Catherine Bowes Rickman
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, 27710, USA. .,Department of Cell Biology, Duke University, Durham, NC, 27710, USA.
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134
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Klingeborn M, Dismuke WM, Bowes Rickman C, Stamer WD. Roles of exosomes in the normal and diseased eye. Prog Retin Eye Res 2017; 59:158-177. [PMID: 28465248 PMCID: PMC5537591 DOI: 10.1016/j.preteyeres.2017.04.004] [Citation(s) in RCA: 111] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 04/28/2017] [Accepted: 04/28/2017] [Indexed: 12/21/2022]
Abstract
Exosomes are nanometer-sized vesicles that are released by cells in a controlled fashion and mediate a plethora of extra- and intercellular activities. Some key functions of exosomes include cell-cell communication, immune modulation, extracellular matrix turnover, stem cell division/differentiation, neovascularization and cellular waste removal. While much is known about their role in cancer, exosome function in the many specialized tissues of the eye is just beginning to undergo rigorous study. Here we review current knowledge of exosome function in the visual system in the context of larger bodies of data from other fields, in both health and disease. Additionally, we discuss recent advances in the exosome field including use of exosomes as a therapeutic vehicle, exosomes as a source of biomarkers for disease, plus current standards for isolation and validation of exosome populations. Finally, we use this foundational information about exosomes in the eye as a platform to identify areas of opportunity for future research studies.
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Affiliation(s)
- Mikael Klingeborn
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC 27710, USA
| | - W Michael Dismuke
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC 27710, USA
| | - Catherine Bowes Rickman
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC 27710, USA; Department of Cell Biology, Duke University, Durham, NC 27710, USA
| | - W Daniel Stamer
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC 27710, USA; Department of Biomedical Engineering, Duke University, Durham, NC 27710, USA.
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135
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Landfried B, Grimm C. Neuroprotektion geschädigter Photorezeptoren. MED GENET-BERLIN 2017. [DOI: 10.1007/s11825-017-0130-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Zusammenfassung
Der Schutz der Sehzellen durch Neuroprotektion ist ein vielversprechender Ansatz, der bei vielen degenerativen Netzhauterkrankungen entweder als Mono- oder Kombinationstherapie zum Einsatz kommen könnte. Viele neuroprotektive Substanzen wurden im Tiermodell identifiziert und erfolgreich getestet. Einige dieser Substanzen wurden auch bereits in klinischen Versuchen am Patienten untersucht, allerdings mit unterschiedlichem Erfolg. Diverse Versuchsansätze werden derzeit überprüft.
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Affiliation(s)
- Britta Landfried
- Aff1 0000 0004 0478 9977 grid.412004.3 Augenklinik Universitätsspital Zürich Zürich Schweiz
- Aff4 0000 0004 1937 0650 grid.7400.3 Labor für Zellbiologie der Netzhaut, Augenklinik Universität Zürich Wagistrasse 14 8952 Schlieren Schweiz
| | - Christian Grimm
- Aff1 0000 0004 0478 9977 grid.412004.3 Augenklinik Universitätsspital Zürich Zürich Schweiz
- Aff2 0000 0004 1937 0650 grid.7400.3 Zentrum für integrative Humanphysiologie (ZIHP) Universität Zürich Zürich Schweiz
- Aff3 0000 0004 1937 0650 grid.7400.3 Zentrum für Neurowissenschaften Zürich (ZNZ) Universität Zürich Zürich Schweiz
- Aff4 0000 0004 1937 0650 grid.7400.3 Labor für Zellbiologie der Netzhaut, Augenklinik Universität Zürich Wagistrasse 14 8952 Schlieren Schweiz
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136
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Knickelbein JE, Liu B, Arakelyan A, Zicari S, Hannes S, Chen P, Li Z, Grivel JC, Chaigne-Delalande B, Sen HN, Margolis L, Nussenblatt RB. Modulation of Immune Responses by Extracellular Vesicles From Retinal Pigment Epithelium. Invest Ophthalmol Vis Sci 2017; 57:4101-7. [PMID: 27537259 PMCID: PMC4991022 DOI: 10.1167/iovs.15-18353] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Purpose Extracellular vesicles (EV), such as exosomes, are important mediators of intercellular communication and have been implicated in modulation of the immune system. We investigated if EV released from retinal pigment epithelium (RPE) modulate immune responses in vitro. Methods Extracellular vesicles were isolated from ARPE-19 cultures stimulated or not with the inflammatory cytokines IL-1β, IFN-γ, and TNF-α. Isolated EV were characterized by nanoparticle flow and Western blot analyses. Retinal pigment epithelium–derived EV were cultured with human peripheral blood mononuclear cells, which were assayed for T-cell proliferation by 3H-thymidine incorporation. Retinal pigment epithelium–derived EV were also independently cultured with enriched lymphocytes or monocytes. Cell phenotype and cell death were evaluated by flow cytometric analysis. Cytokine levels were assayed in culture supernatants by multiplex bead analysis. Results The concentration of ARPE-derived EV from cytokine-stimulated cultures was slightly higher than from nonstimulated cultures. The size of EV was approximately 100 nm in both groups. Extracellular vesicles from both nonstimulated and cytokine-stimulated ARPE-19 significantly inhibited T-cell proliferation without affecting T-cell viability. Culture of EV from nonstimulated ARPE-19 with undifferentiated human monocytes induced an immunoregulatory phenotype with a significantly higher percentage of CD14++CD16+ monocytes and upregulation of TGF-β1. Culture of EV from cytokine-stimulated ARPE-19 cells with human monocytes induced upregulation of several proinflammatory cytokines and monocyte death. Conclusions Retinal pigment epithelium cells constitutively secrete EV in the size range of exosomes, with increased release from RPE cells stimulated with inflammatory cytokines. Extracellular vesicles from both nonstimulated and cytokine-stimulated RPE inhibited T-cell stimulation. Extracellular vesicles from nonstimulated ARPE-19 cells promoted an immunoregulatory CD14++CD16+ phenotype in human monocytes, while EV from cytokine-stimulated ARPE-19 cells caused human monocyte death. These findings suggest that RPE cells use EV to induce a downregulatory immune environment under homeostatic conditions. In an inflammatory milieu, RPE-derived EV may mitigate a potentially harmful inflammatory response through killing of monocytes.
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Affiliation(s)
- Jared E Knickelbein
- Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Baoying Liu
- Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Anush Arakelyan
- Section of Intercellular Interactions, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, Bethesda, Maryland, United States
| | - Sonia Zicari
- Section of Intercellular Interactions, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, Bethesda, Maryland, United States
| | - Susan Hannes
- Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Ping Chen
- Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Zhiyu Li
- Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Jean-Charles Grivel
- Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States 2Section of Intercellular Interactions, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, Bethesda, Maryland
| | - Benjamin Chaigne-Delalande
- Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - H Nida Sen
- Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Leonid Margolis
- Section of Intercellular Interactions, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, Bethesda, Maryland, United States
| | - Robert B Nussenblatt
- Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
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137
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Zhang Y, Cross SD, Stanton JB, Marmorstein AD, Le YZ, Marmorstein LY. Early AMD-like defects in the RPE and retinal degeneration in aged mice with RPE-specific deletion of Atg5 or Atg7. Mol Vis 2017; 23:228-241. [PMID: 28465655 PMCID: PMC5398883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 04/12/2017] [Indexed: 11/08/2022] Open
Abstract
PURPOSE To examine the effects of autophagy deficiency induced by RPE-specific deletion of Atg5 or Atg7 in mice as a function of age. METHODS Conditional knockout mice with a floxed allele of Atg5 or Atg7 were crossed with inducible VMD2-rtTA/Cre transgenic mice. VMD2-directed RPE-specific Cre recombinase expression was induced with doxycycline feeding in the resulting mice. Cre-mediated deletion of floxed Atg5 or Atg7 resulted in RPE-specific inactivation of the Atg5 or Atg7 gene. Plastic and thin retinal sections were analyzed with light and electron microscopy for histological changes. Photoreceptor outer segment (POS) thickness in plastic sections was measured using the Adobe Photoshop CS4 extended ruler tool. Autophagic adaptor p62/SQSTM1 and markers for oxidatively damaged lipids, proteins, and DNA were examined with immunofluorescence staining of cryosections. Fluorescence signals were quantified using Image J software. RESULTS Accumulation of p62/SQSTM1 reflecting autophagy deficiency was observed in the RPE of the Atg5ΔRPE and Atg7ΔRPE mice. 3-nitrotyrosine, advanced glycation end products (AGEs), and 8-hydroxy-2'-deoxyguanosine (8-OHdG), markers for oxidatively damaged proteins and DNA, were also found to accumulate in the RPE of these mice. We observed retinal degeneration in 35% of the Atg5ΔRPE mice and 45% of the Atg7ΔRPE mice at 8 to 24 months old. Degeneration severity and the number of mice with degeneration increased with age. The mean POS thickness of these mice was 25 µm at 8-12 months, 15 µm at 13-18 months, and 3 µm at 19-24 months, compared to 35 µm, 30 µm, and 24 µm in the wild-type mice, respectively. Early age-related macular degeneration (AMD)-like RPE defects were found in all the Atg5ΔRPE and Atg7ΔRPE mice 13 months old or older, including vacuoles, uneven RPE thickness, diminished basal infoldings, RPE hypertrophy/hypotrophy, pigmentary irregularities, and necrosis. The severity of the RPE defects increased with age and in the mice with retinal degeneration. RPE atrophy and choroidal neovascularization (CNV) were occasionally observed in the Atg5ΔRPE and Atg7ΔRPE mice with advanced age. CONCLUSIONS Autophagy deficiency induced by RPE-specific deletion of Atg5 or Atg7 predisposes but does not necessarily drive the development of AMD-like phenotypes or retinal degeneration.
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Affiliation(s)
- Youwen Zhang
- Department of Ophthalmology, Mayo Clinic, Rochester, MN
| | | | - James B. Stanton
- Department of Ophthalmology & Vision Science, University of Arizona, Tucson, AZ
| | | | - Yun Zheng Le
- Department of Medicine and Harold Hamm Diabetes Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK
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Lei L, Tzekov R, Li H, McDowell JH, Gao G, Smith WC, Tang S, Kaushal S. Inhibition or Stimulation of Autophagy Affects Early Formation of Lipofuscin-Like Autofluorescence in the Retinal Pigment Epithelium Cell. Int J Mol Sci 2017; 18:ijms18040728. [PMID: 28353645 PMCID: PMC5412314 DOI: 10.3390/ijms18040728] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 03/23/2017] [Accepted: 03/24/2017] [Indexed: 12/22/2022] Open
Abstract
The accumulation of lipofuscin in the retinal pigment epithelium (RPE) is dependent on the effectiveness of photoreceptor outer segment material degradation. This study explored the role of autophagy in the fate of RPE lipofuscin degradation. After seven days of feeding with either native or modified rod outer segments, ARPE-19 cells were treated with enhancers or inhibitors of autophagy and the autofluorescence was detected by fluorescence-activated cell sorting. Supplementation with different types of rod outer segments increased lipofuscin-like autofluorescence (LLAF) after the inhibition of autophagy, while the induction of autophagy (e.g., application of rapamycin) decreased LLAF. The effects of autophagy induction were further confirmed by Western blotting, which showed the conversion of LC3-I to LC3-II, and by immunofluorescence microscopy, which detected the lysosomal activity of the autophagy inducers. We also monitored LLAF after the application of several autophagy inhibitors by RNA-interference and confocal microscopy. The results showed that, in general, the inhibition of the autophagy-related proteins resulted in an increase in LLAF when cells were fed with rod outer segments, which further confirms the effect of autophagy in the fate of RPE lipofuscin degradation. These results emphasize the complex role of autophagy in modulating RPE autofluorescence and confirm the possibility of the pharmacological clearance of RPE lipofuscin by small molecules.
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Affiliation(s)
- Lei Lei
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, No.54 South Xianlie Road, Guangzhou 510060, China.
- Department of Ophthalmology, University of Massachusetts Medical School, 381 Plantation Street, Worcester, MA 01605, USA.
| | - Radouil Tzekov
- Department of Ophthalmology, University of Massachusetts Medical School, 381 Plantation Street, Worcester, MA 01605, USA.
- Department of Ophthalmology, University of South Florida, 13127 USF Magnolia Drive, Tampa, FL 33612, USA.
- The Roskamp Institute, 2040 Whitfield Avenue, Sarasota, FL 34243, USA.
| | - Huapeng Li
- Gene Therapy Center, University of Massachusetts Medical School, 381 Plantation Street, Worcester, MA 01605, USA.
| | - J Hugh McDowell
- The Department of Ophthalmology, University of Florida Health Science Center, 1600 SW Archer Road, Gainesville, FL 32610, USA.
| | - Guangping Gao
- Gene Therapy Center, University of Massachusetts Medical School, 381 Plantation Street, Worcester, MA 01605, USA.
| | - W Clay Smith
- The Department of Ophthalmology, University of Florida Health Science Center, 1600 SW Archer Road, Gainesville, FL 32610, USA.
| | - Shibo Tang
- Aier School of Ophthalmology, Central South University, Floor 4, New Century Building, 198# Furong Middle Road, Changsha 410015, China.
| | - Shalesh Kaushal
- Department of Ophthalmology, University of Massachusetts Medical School, 381 Plantation Street, Worcester, MA 01605, USA.
- VRMI, 6205 NW 81st Drive, Gainesville, FL 32653, USA.
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139
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Involvement of Nrf2 in Ocular Diseases. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2017; 2017:1703810. [PMID: 28473877 PMCID: PMC5394909 DOI: 10.1155/2017/1703810] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 03/14/2017] [Indexed: 12/15/2022]
Abstract
The human body harbors within it an intricate and delicate balance between oxidants and antioxidants. Any disruption in this checks-and-balances system can lead to harmful consequences in various organs and tissues, such as the eye. This review focuses on the effects of oxidative stress and the role of a particular antioxidant system—the Keap1-Nrf2-ARE pathway—on ocular diseases, specifically age-related macular degeneration, cataracts, diabetic retinopathy, and glaucoma. Together, they are the major causes of blindness in the world.
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140
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Manthey AL, Liu W, Jiang ZX, Lee MHK, Ji J, So KF, Lai JSM, Lee VWH, Chiu K. Using Electrical Stimulation to Enhance the Efficacy of Cell Transplantation Therapies for Neurodegenerative Retinal Diseases: Concepts, Challenges, and Future Perspectives. Cell Transplant 2017; 26:949-965. [PMID: 28155808 DOI: 10.3727/096368917x694877] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Disease or trauma-induced loss or dysfunction of neurons in any central nervous system (CNS) tissue will have a significant impact on the health of the affected patient. The retina is a multilayered tissue that originates from the neuroectoderm, much like the brain and spinal cord. While sight is not required for life, neurodegeneration-related loss of vision not only affects the quality of life for the patient but also has societal implications in terms of health care expenditure. Thus, it is essential to develop effective strategies to repair the retina and prevent disease symptoms. To address this need, multiple techniques have been investigated for their efficacy in treating retinal degeneration. Recent advances in cell transplantation (CT) techniques in preclinical, animal, and in vitro culture studies, including further evaluation of endogenous retinal stem cells and the differentiation of exogenous adult stem cells into various retinal cell types, suggest that this may be the most appropriate option to replace lost retinal neurons. Unfortunately, the various limitations of CT, such as immune rejection or aberrant cell behavior, have largely prevented this technique from becoming a widely used clinical treatment option. In parallel with the advances in CT methodology, the use of electrical stimulation (ES) to treat retinal degeneration has also been recently evaluated with promising results. In this review, we propose that ES could be used to enhance CT therapy, whereby electrical impulses can be applied to the retina to control both native and transplanted stem cell behavior/survival in order to circumvent the limitations associated with retinal CT. To highlight the benefits of this dual treatment, we have briefly outlined the recent developments and limitations of CT with regard to its use in the ocular environment, followed by a brief description of retinal ES, as well as described their combined use in other CNS tissues.
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141
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Golestaneh N, Chu Y, Xiao YY, Stoleru GL, Theos AC. Dysfunctional autophagy in RPE, a contributing factor in age-related macular degeneration. Cell Death Dis 2017; 8:e2537. [PMID: 28055007 PMCID: PMC5386365 DOI: 10.1038/cddis.2016.453] [Citation(s) in RCA: 236] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 12/05/2016] [Accepted: 12/07/2016] [Indexed: 12/17/2022]
Abstract
Age-related macular degeneration (AMD) is a devastating neurodegenerative disease and a major cause of blindness in the developed world. Owing to its complexity and the lack of an adequate human model that recapitulates key aspects of the disease, the molecular mechanisms of AMD pathogenesis remain poorly understood. Here we show that cultured human retinal pigment epithelium (RPE) from AMD donors (AMD RPE) are functionally impaired and exhibit distinct phenotypes compared with RPE cultured from normal donors (normal RPE). Accumulation of lipid droplets and glycogen granules, disintegration of mitochondria, and an increase in autophagosomes were observed in AMD RPE cultures. Compared with normal RPE, AMD RPE exhibit increased susceptibility to oxidative stress, produce higher levels of reactive oxygen species (ROS) under stress conditions, and showed reduced mitochondrial activity. Measurement of the ratio of LC3-II/ LC3-I, revealed impaired autophagy in AMD RPE as compared with normal RPE. Autophagic flux was also reduced in AMD RPE as compared with normal RPE, as shown by inability of AMD RPE to downregulate p62 levels during starvation. Impaired autophagic pathways were further shown by analyzing late autophagic vesicles; immunostaining with lysosome-associated membrane protein 1 (LAMP-1) antibody revealed enlarged and annular LAMP-1-positive organelles in AMD RPE as opposed to smaller discrete puncta observed in normal RPE. Our study provides insights into AMD cellular and molecular mechanisms, proposes dysfunctional autophagy as an underlying mechanism contributing to the pathophysiology of the disease, and opens up new avenues for development of novel treatment strategies.
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Affiliation(s)
- Nady Golestaneh
- Department of Ophthalmology, Georgetown University Medical Center, Washington, DC, USA
- Department of Neurology, Georgetown University Medical Center, Washington, DC, USA
- Department of Biochemistry and Molecular & Cellular Biology, Georgetown University Medical Center, Washington, DC, USA
| | - Yi Chu
- Department of Ophthalmology, Georgetown University Medical Center, Washington, DC, USA
| | - Yang-Yu Xiao
- Department of Ophthalmology, Georgetown University Medical Center, Washington, DC, USA
| | - Gianna L Stoleru
- Department of Ophthalmology, Georgetown University Medical Center, Washington, DC, USA
| | - Alexander C Theos
- Department of Human Science, Georgetown University, Washington, DC, USA
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142
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Baek A, Yoon S, Kim J, Baek YM, Park H, Lim D, Chung H, Kim DE. Autophagy and KRT8/keratin 8 protect degeneration of retinal pigment epithelium under oxidative stress. Autophagy 2017; 13:248-263. [PMID: 28045574 DOI: 10.1080/15548627.2016.1256932] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Contribution of autophagy and regulation of related proteins to the degeneration of retinal pigment epithelium (RPE) in age-related macular degeneration (AMD) remain unknown. We report that upregulation of KRT8 (keratin 8) as well as its phosphorylation are accompanied with autophagy and attenuated with the inhibition of autophagy in RPE cells under oxidative stress. KRT8 appears to have a dual role in RPE pathophysiology. While increased expression of KRT8 following autophagy provides a cytoprotective role in RPE, phosphorylation of KRT8 induces pathologic epithelial-mesenchymal transition (EMT) of RPE cells under oxidative stress, which is mediated by MAPK1/ERK2 (mitogen-activated protein kinase 1) and MAPK3/ERK1. Inhibition of autophagy further promotes EMT, which can be reversed by inhibition of MAPK. Thus, regulated enhancement of autophagy with concurrent increased expression of KRT8 and the inhibition of KRT8 phosphorylation serve to inhibit oxidative stress-induced EMT of RPE cells as well as to prevent cell death, suggesting that pharmacological manipulation of KRT8 upregulation through autophagy with combined inhibition of the MAPK1/3 pathway may be attractive therapeutic strategies for the treatment of AMD.
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Affiliation(s)
- Ahruem Baek
- a Department of Bioscience and Biotechnology , Konkuk University , Gwangjin-gu , Seoul , Korea
| | - Soojin Yoon
- a Department of Bioscience and Biotechnology , Konkuk University , Gwangjin-gu , Seoul , Korea
| | - Jean Kim
- b Department of Ophthalmology , Konkuk University School of Medicine , Gwangjin-gu , Seoul , Korea
| | - Yu Mi Baek
- a Department of Bioscience and Biotechnology , Konkuk University , Gwangjin-gu , Seoul , Korea
| | - Hanna Park
- a Department of Bioscience and Biotechnology , Konkuk University , Gwangjin-gu , Seoul , Korea
| | - Daehan Lim
- b Department of Ophthalmology , Konkuk University School of Medicine , Gwangjin-gu , Seoul , Korea
| | - Hyewon Chung
- b Department of Ophthalmology , Konkuk University School of Medicine , Gwangjin-gu , Seoul , Korea
| | - Dong-Eun Kim
- a Department of Bioscience and Biotechnology , Konkuk University , Gwangjin-gu , Seoul , Korea
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143
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Abstract
Age-related macular degeneration (AMD) is a common condition causing progressive visual impairment, leading to irreversible blindness. Existing diagnostic tools for AMD are limited to clinical signs in the macula and the visual assessment of the patient. The presence of circulating microRNAs (miRNAs) in the peripheral circulatory system with potential as diagnostic, prognostic and/or predictive biomarkers has been reported in a number of conditions/diseases. miRNAs are key regulators of several biological processes, and miRNA dysregulation has been linked with numerous diseases, most remarkably cancer. miRNAs have been shown to be involved in AMD pathology and several miRNAs target genes and signaling pathways were identified in relation to AMD pathogenesis. Exosomes are 50-90 nm membrane micro-vesicles (MVs), released by several cell types. Although exosomal functions are not completely understood, there is much evidence to suggest that exosomes play an essential role in cell-cell communication. They may stimulate target cells by transferring different bioactive molecules such as miRNA. Here we discuss methods to isolate exosome using serum specimens from AMD patients and miRNA profiling for the better understanding of the disease.
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Affiliation(s)
- Hanan Elshelmani
- Zoology Department, School of Natural Sciences, Trinity College Dublin, Dublin 2, Ireland
| | - Sweta Rani
- Department of Science, Waterford Institute of Technology, Main Campus Cork Road, Waterford, Ireland.
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144
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Golestaneh N, Chu Y, Cheng SK, Cao H, Poliakov E, Berinstein DM. Repressed SIRT1/PGC-1α pathway and mitochondrial disintegration in iPSC-derived RPE disease model of age-related macular degeneration. J Transl Med 2016; 14:344. [PMID: 27998274 PMCID: PMC5175395 DOI: 10.1186/s12967-016-1101-8] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 11/29/2016] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Study of age related macular degeneration (AMD) has been hampered by lack of human models that represent the complexity of the disease. Here we have developed a human in vitro disease model of AMD to investigate the underlying AMD disease mechanisms. METHODS Generation of iPSCs from retinal pigment epithelium (RPE) of AMD donors, age-matched normal donors, skin fibroblasts of a dry AMD patient, and differentiation of iPSCs into RPE (AMD RPE-iPSC-RPE, normal RPE-iPSC-RPE and AMD Skin-iPSC-RPE, respectively). Immunostaining, cell viability assay and reactive oxygen species (ROS) production under oxidative stress conditions, electron microscopy (EM) imaging, ATP production and glycogen concentration assays, quantitative real time PCR, western blot, karyotyping. RESULTS The AMD RPE-iPSC-RPE and AMD Skin-iPSC-RPE present functional impairment and exhibit distinct disease phenotypes compared to RPE-iPSC-RPE generated from normal donors (Normal RPE-iPSC-RPE). The AMD RPE-iPSC-RPE and AMD Skin-iPSC-RPE show increased susceptibility to oxidative stress and produced higher levels of reactive oxygen species (ROS) under stress in accordance with recent reports. The susceptibility to oxidative stress-induced cell death in AMD RPE-iPSC-RPE and Skin-iPSC-RPE was consistent with inability of the AMD RPE-iPSC-RPE and Skin-iPSC-RPE to increase SOD2 expression under oxidative stress. Phenotypic analysis revealed disintegrated mitochondria, accumulation of autophagosomes and lipid droplets in AMD RPE-iPSC-RPE and AMD Skin-iPSC-RPE. Mitochondrial activity was significantly lower in AMD RPE-iPSC-RPE and AMD Skin-iPSC-RPE compared to normal cells and glycogen concentration was significantly increased in the diseased cells. Furthermore, Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), a regulator of mitochondrial biogenesis and function was repressed, and lower expression levels of NAD-dependent deacetylase sirtuin1 (SIRT1) were found in AMD RPE-iPSC-RPE and AMD Skin-iPSC-RPE as compared to normal RPE-iPSC-RPE. CONCLUSIONS Our studies suggest SIRT1/PGC-1α as underlying pathways contributing to AMD pathophysiology, and open new avenues for development of targeted drugs for treatment of this devastating neurodegenerative disease of the visual system.
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Affiliation(s)
- Nady Golestaneh
- Department of Ophthalmology, Georgetown University Medical Center, 3900 Reservoir Road NW, Medical-Dental Building, Room NE203, Washington, DC 20057 USA
- Department of Neurology, Georgetown University Medical Center, Washington, DC USA
- Department of Biochemistry and Molecular & Cellular Biology, Georgetown University Medical Center, Washington, DC USA
| | - Yi Chu
- Department of Ophthalmology, Georgetown University Medical Center, 3900 Reservoir Road NW, Medical-Dental Building, Room NE203, Washington, DC 20057 USA
| | - Shuk Kei Cheng
- Department of Ophthalmology, Georgetown University Medical Center, 3900 Reservoir Road NW, Medical-Dental Building, Room NE203, Washington, DC 20057 USA
| | - Hong Cao
- Department of Ophthalmology, Georgetown University Medical Center, 3900 Reservoir Road NW, Medical-Dental Building, Room NE203, Washington, DC 20057 USA
| | - Eugenia Poliakov
- Retinal Cell and Molecular Biology (LRCMB), National Eye Institute, National Institutes of Health, Bethesda, MD USA
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Extracellular Vesicles and Autophagy in Osteoarthritis. BIOMED RESEARCH INTERNATIONAL 2016; 2016:2428915. [PMID: 28078284 PMCID: PMC5203887 DOI: 10.1155/2016/2428915] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 11/09/2016] [Accepted: 11/13/2016] [Indexed: 12/31/2022]
Abstract
Osteoarthritis (OA) is a type of chronic joint disease that is characterized by the degeneration and loss of articular cartilage and hyperplasia of the synovium and subchondral bone. There is reasonable knowledge about articular cartilage physiology, biochemistry, and chondrocyte metabolism. However, the etiology and pathogenesis of OA remain unclear and need urgent clarification to guide the early diagnosis and treatment of OA. Extracellular vesicles (EVs) are small membrane-linking particles that are released from cells. In recent decades, several special biological properties have been found in EV, especially in terms of cartilage. Autophagy plays a critical role in the regulation of cellular homeostasis. Likewise, more and more research has gradually focused on the effect of autophagy on chondrocyte proliferation and function in OA. The synthesis and release of EV are closely associated with autophagy. At the same time, both EV and autophagy play a role in OA development. Based on the mechanism of EV and autophagy in OA development, EV may be beneficial in the early diagnosis of OA; on the other hand, the combination of EV and autophagy-related regulatory drugs may provide insight into possible OA therapeutic strategies.
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146
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Tong Y, Zhou YL, Wang YX, Zhao PQ, Wang ZY. Retinal pigment epithelium cell-derived exosomes: Possible relevance to CNV in wet-age related macular degeneration. Med Hypotheses 2016; 97:98-101. [DOI: 10.1016/j.mehy.2016.10.027] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 10/26/2016] [Indexed: 12/29/2022]
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147
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Chai P, Ni H, Zhang H, Fan X. The Evolving Functions of Autophagy in Ocular Health: A Double-edged Sword. Int J Biol Sci 2016; 12:1332-1340. [PMID: 27877085 PMCID: PMC5118779 DOI: 10.7150/ijbs.16245] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 08/08/2016] [Indexed: 12/19/2022] Open
Abstract
Autophagy plays an adaptive role in cell survival, development, differentiation and intracellular homeostasis. Autophagy is recognized as a 'self-cannibalizing' process that is active during stresses such as starvation, chemotherapy, infection, ageing, and oxygen shortage to protect organisms from various irritants and to regenerate materials and energy. However, autophagy can also lead to a form of programmed cell death distinct from apoptosis. Components of the autophagic pathway are constitutively expressed at a high level in the eye, including in the cornea, lens, retina, and orbit. In addition, the activation of autophagy is directly linked to the development of eye diseases such as age-related macular degeneration (ARMD), cataracts, diabetic retinopathy (DR), glaucoma, photoreceptor degeneration, ocular tumours, ocular infections and thyroid-associated ophthalmopathy (TAO). A high level of autophagy defends against external stress; however, excessive autophagy can result in deterioration, as observed in ocular diseases such as ARMD and DR. This review summarizes recent developments elucidating the relationship between autophagy and ocular diseases and the potential roles of autophagy in the pathogenesis and treatment of these diseases.
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Affiliation(s)
- Peiwei Chai
- Department of Ophthalmology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, P.R. China
| | - Hongyan Ni
- Department of Ophthalmology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, P.R. China
| | - He Zhang
- Department of Ophthalmology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, P.R. China
| | - Xianqun Fan
- Department of Ophthalmology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, P.R. China
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148
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Dick AD. Doyne lecture 2016: intraocular health and the many faces of inflammation. Eye (Lond) 2016; 31:87-96. [PMID: 27636226 DOI: 10.1038/eye.2016.177] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 07/04/2016] [Indexed: 12/14/2022] Open
Abstract
Dogma for reasons of immune privilege including sequestration (sic) of ocular antigen, lack of lymphatic and immune competent cells in the vital tissues of the eye has long evaporated. Maintaining tissue and cellular health to preserve vision requires active immune responses to prevent damage and respond to danger. A priori the eye must contain immune competent cells, undergo immune surveillance to ensure homoeostasis as well as an ability to promote inflammation. By interrogating immune responses in non-infectious uveitis and compare with age-related macular degeneration (AMD), new concepts of intraocular immune health emerge. The role of macrophage polarisation in the two disorders is a tractable start. TNF-alpha regulation of macrophage responses in uveitis has a pivotal role, supported via experimental evidence and validated by recent trial data. Contrast this with the slow, insidious degeneration in atrophic AMD or in neovasular AMD, with the compelling genetic association with innate immunity and complement, highlights an ability to attenuate pathogenic immune responses and despite known inflammasome activation. Yolk sac-derived microglia maintains tissue immune health. The result of immune cell activation is environmentally dependent, for example, on retinal cell bioenergetics status, autophagy and oxidative stress, and alterations that skew interaction between macrophages and retinal pigment epithelium (RPE). For example, dead RPE eliciting macrophage VEGF secretion but exogenous IL-4 liberates an anti-angiogenic macrophage sFLT-1 response. Impaired autophagy or oxidative stress drives inflammasome activation, increases cytotoxicity, and accentuation of neovascular responses, yet exogenous inflammasome-derived cytokines, such as IL-18 and IL-33, attenuate responses.
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Affiliation(s)
- A D Dick
- UCL Institute of Ophthalmology, London, UK.,Academic unit of Ophthalmology, School of Clinical Sciences, University of Bristol, Bristol, UK.,National Institute for Health Research (NIHR) Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK
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149
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Clearance of autophagy-associated dying retinal pigment epithelial cells - a possible source for inflammation in age-related macular degeneration. Cell Death Dis 2016; 7:e2367. [PMID: 27607582 PMCID: PMC5059849 DOI: 10.1038/cddis.2016.133] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Revised: 04/01/2016] [Accepted: 04/04/2016] [Indexed: 12/17/2022]
Abstract
Retinal pigment epithelial (RPE) cells can undergo different forms of cell death, including autophagy-associated cell death during age-related macular degeneration (AMD). Failure of macrophages or dendritic cells (DCs) to engulf the different dying cells in the retina may result in the accumulation of debris and progression of AMD. ARPE-19 and primary human RPE cells undergo autophagy-associated cell death upon serum depletion and oxidative stress induced by hydrogen peroxide (H2O2). Autophagy was revealed by elevated light-chain-3 II (LC3-II) expression and electron microscopy, while autophagic flux was confirmed by blocking the autophago-lysosomal fusion using chloroquine (CQ) in these cells. The autophagy-associated dying RPE cells were engulfed by human macrophages, DCs and living RPE cells in an increasing and time-dependent manner. Inhibition of autophagy by 3-methyladenine (3-MA) decreased the engulfment of the autophagy-associated dying cells by macrophages, whereas sorting out the GFP-LC3-positive/autophagic cell population or treatment by the glucocorticoid triamcinolone (TC) enhanced it. Increased amounts of IL-6 and IL-8 were released when autophagy-associated dying RPEs were engulfed by macrophages. Our data suggest that cells undergoing autophagy-associated cell death engage in clearance mechanisms guided by professional and non-professional phagocytes, which is accompanied by inflammation as part of an in vitro modeling of AMD pathogenesis.
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150
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Sardell RJ, Bailey JNC, Courtenay MD, Whitehead P, Laux RA, Adams LD, Fortun JA, Brantley MA, Kovach JL, Schwartz SG, Agarwal A, Scott WK, Haines JL, Pericak-Vance MA. Whole exome sequencing of extreme age-related macular degeneration phenotypes. Mol Vis 2016; 22:1062-76. [PMID: 27625572 PMCID: PMC5007100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 08/27/2016] [Indexed: 11/29/2022] Open
Abstract
PURPOSE Demographic, environmental, and genetic risk factors for age-related macular degeneration (AMD) have been identified; however, a substantial portion of the variance in AMD disease risk and heritability remains unexplained. To identify AMD risk variants and generate hypotheses for future studies, we performed whole exome sequencing for 75 individuals whose phenotype was not well predicted by their genotype at known risk loci. We hypothesized that these phenotypically extreme individuals were more likely to carry rare risk or protective variants with large effect sizes. METHODS A genetic risk score was calculated in a case-control set of 864 individuals (467 AMD cases, 397 controls) based on 19 common (≥1% minor allele frequency, MAF) single nucleotide variants previously associated with the risk of advanced AMD in a large meta-analysis of advanced cases and controls. We then selected for sequencing 39 cases with bilateral choroidal neovascularization with the lowest genetic risk scores to detect risk variants and 36 unaffected controls with the highest genetic risk score to detect protective variants. After minimizing the influence of 19 common genetic risk loci on case-control status, we targeted single variants of large effect and the aggregate effect of weaker variants within genes and pathways. Single variant tests were conducted on all variants, while gene-based and pathway analyses were conducted on three subsets of data: 1) rare (≤1% MAF in the European population) stop, splice, or damaging missense variants, 2) all rare variants, and 3) all variants. All analyses controlled for the effects of age and sex. RESULTS No variant, gene, or pathway outside regions known to be associated with risk for advanced AMD reached genome-wide significance. However, we identified several variants with substantial differences in allele frequency between cases and controls with strong additive effects on affection status after controlling for age and sex. Protective effects trending toward significance were detected at two loci identified in single-variant analyses: an intronic variant in FBLN7 (the gene encoding fibulin 7) and at three variants near pyridoxal (pyridoxine, vitamin B6) kinase (PDXK). Aggregate rare-variant analyses suggested evidence for association at ASRGL1, a gene previously linked to photoreceptor cell death, and at BSDC1. In known AMD loci we also identified 29 novel or rare damaging missense or stop/splice variants in our sample of cases and controls. CONCLUSIONS Identified variants and genes may highlight regions important in the pathogenesis of AMD and are key targets for replication.
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Affiliation(s)
- Rebecca J. Sardell
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL
| | - Jessica N Cooke Bailey
- Department of Epidemiology and Biostatistics, Case Western Reserve University, Cleveland, OH
| | - Monique D. Courtenay
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL
| | - Patrice Whitehead
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL
| | - Reneé A. Laux
- Department of Epidemiology and Biostatistics, Case Western Reserve University, Cleveland, OH
| | - Larry D. Adams
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL
| | - Jorge A. Fortun
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL
| | - Milam A. Brantley
- Department of Ophthalmology and Visual Sciences, Vanderbilt University School of Medicine, Nashville, TN
| | - Jaclyn L. Kovach
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL
| | - Stephen G. Schwartz
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL
| | - Anita Agarwal
- Department of Ophthalmology and Visual Sciences, Vanderbilt University School of Medicine, Nashville, TN
| | - William K. Scott
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL
| | - Jonathan L. Haines
- Department of Epidemiology and Biostatistics, Case Western Reserve University, Cleveland, OH
| | - Margaret A. Pericak-Vance
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL
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