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Molcak H, Jiang K, Campbell CJ, Matsubara JA. Purinergic signaling via P2X receptors and mechanisms of unregulated ATP release in the outer retina and age-related macular degeneration. Front Neurosci 2023; 17:1216489. [PMID: 37496736 PMCID: PMC10366617 DOI: 10.3389/fnins.2023.1216489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 06/26/2023] [Indexed: 07/28/2023] Open
Abstract
Age-related macular degeneration (AMD) is a chronic and progressive inflammatory disease of the retina characterized by photoceptor loss and significant central visual impairment due to either choroidal neovascularization or geographic atrophy. The pathophysiology of AMD is complex and multifactorial, driven by a combination of modifiable and non-modifiable risk factors, molecular mechanisms, and cellular processes that contribute to overall disease onset, severity, and progression. Unfortunately, due to the structural, cellular, and pathophysiologic complexity, therapeutic discovery is challenging. While purinergic signaling has been investigated for its role in the development and treatment of ocular pathologies including AMD, the potential crosstalk between known contributors to AMD, such as the complement cascade and inflammasome activation, and other biological systems, such as purinergic signaling, have not been fully characterized. In this review, we explore the interactions between purinergic signaling, ATP release, and known contributors to AMD pathogenesis including complement dysregulation and inflammasome activation. We begin by identifying what is known about purinergic receptors in cell populations of the outer retina and potential sources of extracellular ATP required to trigger purinergic receptor activation. Next, we examine evidence in the literature that the purinergic system accelerates AMD pathogenesis leading to apoptotic and pyroptotic cell death in retinal cells. To fully understand the potential role that purinergic signaling plays in AMD, more research is needed surrounding the expression, distribution, functions, and interactions of purinergic receptors within cells of the outer retina as well as potential crosstalk with other systems. By determining how these processes are affected in the context of purinergic signaling, it will improve our understanding of the mechanisms that drive AMD pathogenesis which is critical in developing treatment strategies that prevent or slow progression of the disease.
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Affiliation(s)
- Haydn Molcak
- Matsubara Lab, Faculty of Medicine, Department of Ophthalmology and Visual Sciences, Eye Care Centre, Vancouver, BC, Canada
| | - Kailun Jiang
- Matsubara Lab, Faculty of Medicine, Department of Ophthalmology and Visual Sciences, Eye Care Centre, Vancouver, BC, Canada
| | | | - Joanne A. Matsubara
- Matsubara Lab, Faculty of Medicine, Department of Ophthalmology and Visual Sciences, Eye Care Centre, Vancouver, BC, Canada
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Karema-Jokinen V, Koskela A, Hytti M, Hongisto H, Viheriälä T, Liukkonen M, Torsti T, Skottman H, Kauppinen A, Nymark S, Kaarniranta K. Crosstalk of protein clearance, inflammasome, and Ca 2+ channels in retinal pigment epithelium derived from age-related macular degeneration patients. J Biol Chem 2023:104770. [PMID: 37137441 DOI: 10.1016/j.jbc.2023.104770] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 04/21/2023] [Accepted: 04/23/2023] [Indexed: 05/05/2023] Open
Abstract
Degeneration and/or dysfunction of retinal pigment epithelium (RPE) is generally detected as the formation of intra- and extracellular protein aggregates, called lipofuscin and drusen, respectively, in patients with age-related macular degeneration (AMD), the leading cause of blindness in the elderly population. These clinical hallmarks are linked to dysfunctional protein homeostasis and inflammation, and furthermore, are both regulated by changes in intracellular Ca2+ concentration. While many other cellular mechanisms have been considered in the investigations of AMD-RPE, there has been relatively little work on understanding the interactions of protein clearance, inflammation, and Ca2+ dynamics in disease pathogenesis. Here we established induced pluripotent stem cell-derived RPE from two patients with advanced AMD and from an age- and gender-matched control subject. We studied autophagy and inflammasome activation under disturbed proteostasis in these cell lines and investigated changes in their intracellular Ca2+ concentration and L-type voltage-gated Ca2+ channels. Our work demonstrated dysregulated autophagy and inflammasome activation in AMD-RPE accompanied by reduced intracellular free Ca2+ levels. Interestingly, we found currents through L-type voltage-gated Ca2+ channels to be diminished and showed these channels to be significantly localized to intracellular compartments in AMD-RPE. Taken together, the alterations in Ca2+ dynamics in AMD-RPE together with dysregulated autophagy and inflammasome activation indicate an important role for Ca2+ signaling in AMD pathogenesis, providing new avenues for the development of therapeutic approaches.
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Affiliation(s)
| | - Ali Koskela
- Department of Ophthalmology, University of Eastern Finland, Kuopio, Finland
| | - Maria Hytti
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland
| | - Heidi Hongisto
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland; Department of Ophthalmology, University of Eastern Finland, Kuopio, Finland
| | - Taina Viheriälä
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Mikko Liukkonen
- Department of Ophthalmology, University of Eastern Finland, Kuopio, Finland
| | - Tommi Torsti
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland
| | - Heli Skottman
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Anu Kauppinen
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland
| | - Soile Nymark
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland.
| | - Kai Kaarniranta
- Department of Ophthalmology, University of Eastern Finland, Kuopio, Finland; Department of Ophthalmology, Kuopio University Hospital, Finland, Immuno-Ophthalmology, School of Pharmacy, University of Eastern Finland, Kuopio, Finland; Department of Molecular Genetics, University of Lodz, Lodz, Poland.
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Imraish A, Abu-Thiab T, Hammad H. P 2X and P2Y receptor antagonists reduce inflammation in ATP-induced microglia. Pharm Pract (Granada) 2023; 21:2788. [PMID: 37090457 PMCID: PMC10117305 DOI: 10.18549/pharmpract.2023.1.2788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 12/05/2022] [Indexed: 04/25/2023] Open
Abstract
Background P2 receptors have been implicated in the release of neurotransmitter and pro-inflammatory cytokines due to their response to neuro-excitatory substances in the microglia. The P2X4, P2X7 and P2Y12 receptors are involved in the development of pain behavior induced by peripheral nerve injury. However, it is not known if blocking P2X4, P2X7 and P2Y12 receptors is associated with the expression and the release of interleukin-1B (IL-1β), interleukin-6 (IL-6), or tumor necrosis factor-α (TNF-α) in cultured neonatal spinal cord microglia. Objective For this reason, we examined the effects of P2X4, P2X7 and P2Y12 antagonists on the expression and the release of IL-1β, IL-6, and TNF-α in ATP-stimulated microglia. Methods In this study, we observed the effect of A-740003, PSB-12062 and MRS 2395 (P2X4, P2X7 and P2Y12 receptors antagonist, respectively), on the expression and release of IL-1β, IL-6 and TNF-α by using real-time fluorescence quantitative polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA). Results ATP induced the increased expression of IL-1β, IL-6 and TNF-α at the level of messenger RNA (mRNA). ATP-evoked increase in IL-1β, IL-6 and TNF-α mRNA expression was inhibited by the P2X4 receptor antagonist A-740003 or P2X7 receptor antagonist PSB-12062, respectively. Similarly, ATP-evoked release of IL-1β, IL-6 and TNF-α was inhibited by A-740003 and PSB-12062. Furthermore, ATP-evoked increased expression of Iba-1, IL-1β, IL-6 and TNF-α mRNA, and release of IL-1β, IL-6 and TNF-α were nearly all blocked after co-administration of A-740003 plus PSB-12062. Finally, ATP-evoked increased gene expression and release of IL-1β, IL-6 and TNF-α were also inhibited by MRS 2395 (P2Y12 antagonist). Conclusion These observations suggest a new clue for therapeutic strategies to treat the neuro-inflammation.
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Affiliation(s)
- Amer Imraish
- Department of Biological Sciences, School of Science, The University of Jordan, Amman, Jordan.
| | - Tuqa Abu-Thiab
- Department of Biological Sciences, School of Science, The University of Jordan, Amman, Jordan.
| | - Hana Hammad
- Department of Biological Sciences, School of Science, The University of Jordan, Amman, Jordan.
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Viheriälä T, Hongisto H, Sorvari J, Skottman H, Nymark S, Ilmarinen T. Cell maturation influences the ability of hESC-RPE to tolerate cellular stress. Stem Cell Res Ther 2022; 13:30. [PMID: 35073969 PMCID: PMC8785579 DOI: 10.1186/s13287-022-02712-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 01/10/2022] [Indexed: 11/15/2022] Open
Abstract
Background Transplantation of human pluripotent stem cell-derived retinal pigment epithelium (RPE) is an urgently needed treatment for the cure of degenerative diseases of the retina. The transplanted cells must tolerate cellular stress caused by various sources such as retinal inflammation and regain their functions rapidly after the transplantation. We have previously shown the maturation level of the cultured human embryonic stem cell-derived RPE (hESC-RPE) cells to influence for example their calcium (Ca2+) signaling properties. Yet, no comparison of the ability of hESC-RPE at different maturity levels to tolerate cellular stress has been reported. Methods Here, we analyzed the ability of the hESC-RPE populations with early (3 weeks) and late (12 weeks) maturation status to tolerate cellular stress caused by chemical cell stressors protease inhibitor (MG132) or hydrogen peroxide (H2O2). After the treatments, the functionality of the RPE cells was studied by transepithelial resistance, immunostainings of key RPE proteins, phagocytosis, mitochondrial membrane potential, Ca2+ signaling, and cytokine secretion. Results The hESC-RPE population with late maturation status consistently showed improved tolerance to cellular stress in comparison to the population with early maturity. After the treatments, the early maturation status of hESC-RPE monolayer showed impaired barrier properties. The hESC-RPE with early maturity status also exhibited reduced phagocytic and Ca2+ signaling properties, especially after MG132 treatment. Conclusions Our results suggest that due to better tolerance to cellular stress, the late maturation status of hESC-RPE population is superior compared to monolayers with early maturation status in the transplantation therapy settings. Supplementary Information The online version contains supplementary material available at 10.1186/s13287-022-02712-7.
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Affiliation(s)
- Taina Viheriälä
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Heidi Hongisto
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland.,Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland
| | - Juhana Sorvari
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Heli Skottman
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Soile Nymark
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Tanja Ilmarinen
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland. .,BioMediTech, Faculty of Medicine and Life Sciences, Tampere University, Arvo Ylpön katu 34, 33520, Tampere, Finland.
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5
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Markitantova YV, Simirskii VN. The Role of the Purinergic Signaling System in the Control of Histogenesis, Homeostasis, and Pathogenesis of the Vertebrate Retina. Russ J Dev Biol 2021. [DOI: 10.1134/s1062360421060084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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6
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Yang M, Qiu R, Wang W, Liu J, Jin X, Li Y, Li L, Lei B. P2X7 Receptor Antagonist Attenuates Retinal Inflammation and Neovascularization Induced by Oxidized Low-Density Lipoprotein. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2021; 2021:5520644. [PMID: 34457115 PMCID: PMC8397555 DOI: 10.1155/2021/5520644] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 06/28/2021] [Accepted: 08/03/2021] [Indexed: 11/30/2022]
Abstract
Age-related macular degeneration (AMD) is a common and severe blinding disease among people worldwide. Retinal inflammation and neovascularization are two fundamental pathological processes in AMD. Recent studies showed that P2X7 receptor was closely involved in the inflammatory response. Here, we aim to investigate whether A740003, a P2X7 receptor antagonist, could prevent retinal inflammation and neovascularization induced by oxidized low-density lipoprotein (ox-LDL) and explore the underlying mechanisms. ARPE-19 cells and C57BL/6 mice were treated with ox-LDL and A740003 successively for in vitro and in vivo studies. In this research, we found that A740003 suppressed reactive oxygen species (ROS) generation and inhibited the activation of Nod-like receptor pyrin-domain protein 3 (NLRP3) inflammasome and nuclear factor-κB (NF-κB) pathway. A740003 also inhibited the generation of angiogenic factors in ARPE-19 cells and angiogenesis in mice. The inflammatory cytokines and phosphorylation of inhibitor of nuclear factor-κB alpha (IKBα) were repressed by A740003. Besides, ERG assessment showed that retinal functions were remarkably preserved in A740003-treated mice. In summary, our results revealed that the P2X7 receptor antagonist reduced retinal inflammation and neovascularization and protected retinal function. The protective effects were associated with regulation of NLRP3 inflammasome and the NF-κB pathway, as well as inhibition of angiogenic factors.
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MESH Headings
- Animals
- Cytokines/metabolism
- Inflammation/chemically induced
- Inflammation/drug therapy
- Inflammation/metabolism
- Inflammation/pathology
- Lipoproteins, LDL/toxicity
- Male
- Mice
- Mice, Inbred C57BL
- NF-kappa B/genetics
- NF-kappa B/metabolism
- NLR Family, Pyrin Domain-Containing 3 Protein/genetics
- NLR Family, Pyrin Domain-Containing 3 Protein/metabolism
- Neovascularization, Pathologic/chemically induced
- Neovascularization, Pathologic/drug therapy
- Neovascularization, Pathologic/metabolism
- Neovascularization, Pathologic/pathology
- Oxidative Stress
- Purinergic P2X Receptor Antagonists/pharmacology
- Reactive Oxygen Species/metabolism
- Receptors, Purinergic P2X7/chemistry
- Receptors, Purinergic P2X7/metabolism
- Retinitis/chemically induced
- Retinitis/drug therapy
- Retinitis/metabolism
- Retinitis/pathology
- Signal Transduction
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Affiliation(s)
- Mingzhu Yang
- Henan Eye Institute, Henan Eye Hospital, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, Henan 450003, China
| | - Ruiqi Qiu
- Henan Eye Institute, Henan Eye Hospital, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, Henan 450003, China
| | - Weiping Wang
- Henan Eye Institute, Henan Eye Hospital, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, Henan 450003, China
| | - Jingyang Liu
- Henan Eye Institute, Henan Eye Hospital, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, Henan 450003, China
| | - Xiuxiu Jin
- Henan Eye Institute, Henan Eye Hospital, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, Henan 450003, China
| | - Ya Li
- Henan Eye Institute, Henan Eye Hospital, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, Henan 450003, China
| | - Lei Li
- Xinxiang Medical University, Xinxiang, Henan 453003, China
| | - Bo Lei
- Henan Eye Institute, Henan Eye Hospital, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, Henan 450003, China
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7
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Loftus SK, Lundh L, Watkins-Chow DE, Baxter LL, Pairo-Castineira E, Nisc Comparative Sequencing Program, Jackson IJ, Oetting WS, Pavan WJ, Adams DR. A custom capture sequence approach for oculocutaneous albinism identifies structural variant alleles at the OCA2 locus. Hum Mutat 2021; 42:1239-1253. [PMID: 34246199 DOI: 10.1002/humu.24257] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 06/02/2021] [Accepted: 06/24/2021] [Indexed: 11/09/2022]
Abstract
Oculocutaneous albinism (OCA) is a heritable disorder of pigment production that manifests as hypopigmentation and altered eye development. Exon sequencing of known OCA genes is unsuccessful in producing a complete molecular diagnosis for a significant number of affected individuals. We sequenced the DNA of individuals with OCA using short-read custom capture sequencing that targeted coding, intronic, and noncoding regulatory regions of known OCA genes, and genome-wide association study-associated pigmentation loci. We identified an OCA2 complex structural variant (CxSV), defined by a 143 kb inverted segment reintroduced in intron 1, upstream of the native location. The corresponding CxSV junctions were observed in 11/390 probands screened. The 143 kb CxSV presents in one family as a copy number variant duplication for the 143 kb region. In the remaining 10/11 families, the 143 kb CxSV acquired an additional 184 kb deletion across the same region, restoring exons 3-19 of OCA2 to a copy-number neutral state. Allele-associated haplotype analysis found rare SNVs rs374519281 and rs139696407 are linked with the 143 kb CxSV in both OCA2 alleles. For individuals in which customary molecular evaluation does not reveal a biallelic OCA diagnosis, we recommend preliminary screening for these haplotype-associated rare variants, followed by junction-specific validation for the OCA2 143 kb CxSV.
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Affiliation(s)
- Stacie K Loftus
- Genetic Disease Research Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Linnea Lundh
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Dawn E Watkins-Chow
- Genetic Disease Research Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Laura L Baxter
- Genetic Disease Research Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Erola Pairo-Castineira
- Roslin Institute, University of Edinburgh, Easter Bush, Edinburgh, UK.,MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, Western General Hospital, University of Edinburgh, Edinburgh, UK
| | | | - Ian J Jackson
- Roslin Institute, University of Edinburgh, Easter Bush, Edinburgh, UK.,MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, Western General Hospital, University of Edinburgh, Edinburgh, UK
| | - William S Oetting
- Department of Experimental and Clinical Pharmacology, University of Minnesota, Minneapolis, Minnesota, USA
| | - William J Pavan
- Genetic Disease Research Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - David R Adams
- Office of the Clinical Director, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, USA
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8
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Constable PA, Kapoor G. Is white the right light for the clinical electrooculogram? Doc Ophthalmol 2021; 143:297-304. [PMID: 34160736 DOI: 10.1007/s10633-021-09845-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 06/14/2021] [Indexed: 11/30/2022]
Abstract
PURPOSE To investigate if a lower luminance monochromatic LED stimulus could be used as an alternative to a high luminance white light for the clinical electrooculogram. METHODS Clinical electrooculograms were recorded in color normal participants (N = 23) aged 22.6 ± 1.2 years, 7 male and 16 female using the standard 100 cd.m-2 white illuminant and four monochromatic LEDs with peak wavelengths of 448, 534, 596 and 634 nm at 30 cd.m-2. Pupils were dilated and there was a 30 cd.m-2pre-adaptation to white light for 2 min followed by 15 min dark adaptation and 20 min recording in the light stimulus using a Ganzfeld stimulator. RESULTS The normalized LP:DTratio for the short wavelength LED (448 nm) was equivalent in amplitude and timing to the ISCEV standard EOG (p = .99). The LP:DTratio for the white (100 cd.m-2) and 448 nm (30 cd.m-2) were (median ± SEM): 2.49 ± .11 and 2.47 ± .11. The time to light-rise peak was also equivalent being 9.0 ± .2 and 8.0 ± .4 min (p = .54). CONCLUSIONS Consideration may be given to using a short wavelength monochromatic stimulus that is more comfortable for the subject than the current 100 cd.m-2 illuminant.
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Affiliation(s)
- Paul A Constable
- Caring Futures Institute, College of Nursing and Health Sciences, Flinders University, PO Box 2100, Adelaide, SA, 5001, Australia.
| | - Garima Kapoor
- College of Medicine and Public Health, Flinders University, Adelaide, Australia
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9
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Viheriälä T, Sorvari J, Ihalainen TO, Mörö A, Grönroos P, Schlie-Wolter S, Chichkov B, Skottman H, Nymark S, Ilmarinen T. Culture surface protein coatings affect the barrier properties and calcium signalling of hESC-RPE. Sci Rep 2021; 11:933. [PMID: 33441679 PMCID: PMC7806758 DOI: 10.1038/s41598-020-79638-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Accepted: 12/04/2020] [Indexed: 12/29/2022] Open
Abstract
Human pluripotent stem cell-derived retinal pigment epithelium (RPE) transplantation is currently under evaluation as treatment for macular degeneration. For therapeutic applications, cryostorage during cell production is typically needed with potential consequences to cell functionality. We have previously shown that the culture substrate affects human embryonic stem cell-derived RPE (hESC-RPE) properties in fresh cultures. Here, we aimed to further identify the role of RPE basement membrane proteins type IV collagen (Col-IV), laminin (LN), and nidogen-1 in the maturation and functionality of hESC-RPE after cryopreservation. In addition to cell attachment and morphology, transepithelial electrical resistance, expression of key RPE proteins, phagocytosis capacity and Ca2+ signalling were analysed. After cryostorage, attachment of hESC-RPE on culture surfaces coated with Col-IV alone was poor. Combining Col-IV and LN with or without nidogen-1 significantly improved cell attachment and barrier properties of the epithelium. Furthermore, functional homogeneity of the hESC-RPE monolayer was enhanced in the presence of nidogen-1. Our results suggest that the choice of coating proteins for the cell culture may have implications to the functional properties of these cells after cryostorage cell banking.
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Affiliation(s)
- Taina Viheriälä
- Faculty of Medicine and Health Technology, BioMediTech, Tampere University, Tampere, Finland
| | - Juhana Sorvari
- Faculty of Medicine and Health Technology, BioMediTech, Tampere University, Tampere, Finland
| | - Teemu O Ihalainen
- Faculty of Medicine and Health Technology, BioMediTech, Tampere University, Tampere, Finland
| | - Anni Mörö
- Faculty of Medicine and Health Technology, BioMediTech, Tampere University, Tampere, Finland
| | - Pyry Grönroos
- Faculty of Medicine and Health Technology, BioMediTech, Tampere University, Tampere, Finland
| | - Sabrina Schlie-Wolter
- Institute for Multiphase Processes, Leibniz University of Hannover, Hannover, Germany
| | - Boris Chichkov
- Institute of Quantum Optics, Leibniz University of Hannover, Hannover, Germany
| | - Heli Skottman
- Faculty of Medicine and Health Technology, BioMediTech, Tampere University, Tampere, Finland
| | - Soile Nymark
- Faculty of Medicine and Health Technology, BioMediTech, Tampere University, Tampere, Finland
| | - Tanja Ilmarinen
- Faculty of Medicine and Health Technology, BioMediTech, Tampere University, Tampere, Finland.
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10
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Effects of Resvega on Inflammasome Activation in Conjunction with Dysfunctional Intracellular Clearance in Retinal Pigment Epithelial (RPE) Cells. Antioxidants (Basel) 2021; 10:antiox10010067. [PMID: 33430331 PMCID: PMC7825790 DOI: 10.3390/antiox10010067] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 12/23/2020] [Accepted: 01/01/2021] [Indexed: 12/12/2022] Open
Abstract
Age-related macular degeneration (AMD) is an eye disease in which retinal pigment epithelium (RPE) cells play a crucial role in maintaining retinal homeostasis and photoreceptors’ functionality. During disease progression, there is increased inflammation with nucleotide-binding domain, leucine-rich repeat, and Pyrin domain 3 (NLRP3) inflammasome activation, oxidative stress, and impaired autophagy in RPE cells. Previously, we have shown that the dietary supplement Resvega reduces reactive oxygen species (ROS) production and induces autophagy in RPE cells. Here, we investigated the ability of Resvega to prevent NLRP3 inflammasome activation with impaired protein clearance in human RPE cells. Cell viability was measured using the lactate dehydrogenase (LDH) and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Enzyme-linked immunosorbent assays (ELISA) were utilized to determine the secretion of cytokines, NLRP3, and vascular endothelial growth factor (VEGF). Caspase-1 activity was measured with a fluorescent labeled inhibitor of caspase-1 (FLICA; FAM-YVAD-FMK) and detected microscopically. Resvega improved the cell membrane integrity, which was evident as reduced LDH leakage from cells. In addition, the caspase-1 activity and NLRP3 release were reduced, as was the secretion of two inflammatory cytokines, interleukin (IL)-1β and IL-8, in IL-1α-primed ARPE-19 cells. According to our results, Resvega can potentially reduce NLRP3 inflammasome-mediated inflammation in RPE cells with impaired protein clearance.
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11
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Shao X, Guha S, Lu W, Campagno KE, Beckel JM, Mills JA, Yang W, Mitchell CH. Polarized Cytokine Release Triggered by P2X7 Receptor from Retinal Pigmented Epithelial Cells Dependent on Calcium Influx. Cells 2020; 9:cells9122537. [PMID: 33255431 PMCID: PMC7760537 DOI: 10.3390/cells9122537] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 11/13/2020] [Accepted: 11/17/2020] [Indexed: 12/20/2022] Open
Abstract
Cytokine release from non-inflammatory cells is a key step in innate immunity, and agonists triggering cytokine release are central in coordinating responses. P2X7 receptor (P2X7R) stimulation by extracellular ATP is best known to active the NLRP3 inflammasome and release IL-1β, but stimulation also leads to release of other cytokines. As cytokine signaling by retinal pigmented epithelial (RPE) cells is implicated in retinal neurodegeneration, the role of P2X7R in release of cytokine IL-6 from RPE cells was investigated. P2X7R stimulation triggered IL-6 release from primary mouse RPE, human iPS-RPE and human ARPE-19 cells. IL-6 release was polarized, with predominant rise across apical membranes. IL-6 release was inhibited by P2X7R antagonists A438079, A839977, and AZ10606120, but not the NRTI lamivudine (3TC), P2X1R antagonist NF279, or P2Y1R antagonist MRS2179. P2X7R-mediated IL-6 release required extracellular Ca2+ and was blocked by Ca2+ chelator BAPTA. IL-6 release and Ca2+ elevation occurred rapidly, consistent with vesicular IL-6 staining in unstimulated cells. P2X7R stimulation did not trigger IL-1β release in these unprimed cells. P2X7R-mediated IL-6 release was enhanced in RPE cells from the ABCA4−/− mouse model of retinal degeneration. In summary, P2X7R stimulation triggers rapid Ca2+-dependent IL-6 release across the apical membrane of RPE cells.
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Affiliation(s)
- Xiaolei Shao
- Shenzhen Eye Hospital, School of Optometry, Shenzhen University, Shenzhen 518060, China;
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, PA 19104, USA; (S.G.); (J.M.B.)
| | - Sonia Guha
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, PA 19104, USA; (S.G.); (J.M.B.)
- Jules Stein Eye Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Wennan Lu
- Department of Basic and Translational Science, University of Pennsylvania, Philadelphia, PA 19104, USA; (W.L.); (K.E.C.)
| | - Keith E. Campagno
- Department of Basic and Translational Science, University of Pennsylvania, Philadelphia, PA 19104, USA; (W.L.); (K.E.C.)
| | - Jonathan M. Beckel
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, PA 19104, USA; (S.G.); (J.M.B.)
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Jason A. Mills
- Department of Ophthalmology, University of Pennsylvania, Philadelphia, PA 19104, USA;
- Kirby Center for Molecular Ophthalmology and Center for Advanced Retinal and Ocular Therapeutics (CAROT), University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Wenli Yang
- Department of Medicine and Institute for Regenerative Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA;
| | - Claire H. Mitchell
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, PA 19104, USA; (S.G.); (J.M.B.)
- Department of Basic and Translational Science, University of Pennsylvania, Philadelphia, PA 19104, USA; (W.L.); (K.E.C.)
- Department of Ophthalmology, University of Pennsylvania, Philadelphia, PA 19104, USA;
- Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104, USA
- Correspondence: ; Tel.: +1-215-573-2176
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Santiago AR, Madeira MH, Boia R, Aires ID, Rodrigues-Neves AC, Santos PF, Ambrósio AF. Keep an eye on adenosine: Its role in retinal inflammation. Pharmacol Ther 2020; 210:107513. [PMID: 32109489 DOI: 10.1016/j.pharmthera.2020.107513] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Adenosine is an endogenous purine nucleoside ubiquitously distributed throughout the body that interacts with G protein-coupled receptors, classified in four subtypes: A1R, A2AR, A2BR and A3R. Among the plethora of functions of adenosine, it has been increasingly recognized as a key mediator of the immune response. Neuroinflammation is a feature of chronic neurodegenerative diseases and contributes to the pathophysiology of several retinal degenerative diseases. Animal models of retinal diseases are helping to elucidate the regulatory roles of adenosine receptors in the development and progression of those diseases. Mounting evidence demonstrates that the adenosinergic system is altered in the retina during pathological conditions, compromising retinal physiology. This review focuses on the roles played by adenosine and the elements of the adenosinergic system (receptors, enzymes, transporters) in the neuroinflammatory processes occurring in the retina. An improved understanding of the molecular and cellular mechanisms of the signalling pathways mediated by adenosine underlying the onset and progression of retinal diseases will pave the way towards the identification of new therapeutic approaches.
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Affiliation(s)
- Ana Raquel Santiago
- Faculty of Medicine, Coimbra Institute for Clinical and Biomedical Research (iCBR), University of Coimbra, 3000-548 Coimbra, Portugal; Center for Innovative Biomedicine and Biotechnology (CIBB), University of Coimbra, 3000-548 Coimbra, Portugal; Association for Innovation and Biomedical Research on Light and Image (AIBILI), Coimbra, 3000-548 Coimbra, Portugal.
| | - Maria H Madeira
- Faculty of Medicine, Coimbra Institute for Clinical and Biomedical Research (iCBR), University of Coimbra, 3000-548 Coimbra, Portugal; Center for Innovative Biomedicine and Biotechnology (CIBB), University of Coimbra, 3000-548 Coimbra, Portugal; Association for Innovation and Biomedical Research on Light and Image (AIBILI), Coimbra, 3000-548 Coimbra, Portugal
| | - Raquel Boia
- Faculty of Medicine, Coimbra Institute for Clinical and Biomedical Research (iCBR), University of Coimbra, 3000-548 Coimbra, Portugal; Center for Innovative Biomedicine and Biotechnology (CIBB), University of Coimbra, 3000-548 Coimbra, Portugal
| | - Inês Dinis Aires
- Faculty of Medicine, Coimbra Institute for Clinical and Biomedical Research (iCBR), University of Coimbra, 3000-548 Coimbra, Portugal; Center for Innovative Biomedicine and Biotechnology (CIBB), University of Coimbra, 3000-548 Coimbra, Portugal
| | - Ana Catarina Rodrigues-Neves
- Faculty of Medicine, Coimbra Institute for Clinical and Biomedical Research (iCBR), University of Coimbra, 3000-548 Coimbra, Portugal; Center for Innovative Biomedicine and Biotechnology (CIBB), University of Coimbra, 3000-548 Coimbra, Portugal
| | - Paulo Fernando Santos
- Faculty of Medicine, Coimbra Institute for Clinical and Biomedical Research (iCBR), University of Coimbra, 3000-548 Coimbra, Portugal; Center for Innovative Biomedicine and Biotechnology (CIBB), University of Coimbra, 3000-548 Coimbra, Portugal; Department of Life Sciences, University of Coimbra, 3000-456 Coimbra, Portugal
| | - António Francisco Ambrósio
- Faculty of Medicine, Coimbra Institute for Clinical and Biomedical Research (iCBR), University of Coimbra, 3000-548 Coimbra, Portugal; Center for Innovative Biomedicine and Biotechnology (CIBB), University of Coimbra, 3000-548 Coimbra, Portugal; Association for Innovation and Biomedical Research on Light and Image (AIBILI), Coimbra, 3000-548 Coimbra, Portugal.
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Analysis of ATP-Induced Ca 2+ Responses at Single Cell Level in Retinal Pigment Epithelium Monolayers. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1185:525-530. [PMID: 31884665 DOI: 10.1007/978-3-030-27378-1_86] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Calcium is one of the most important second messengers in cells and thus involved in a variety of physiological processes. In retinal pigment epithelium (RPE), Ca2+ and its ATP-dependent signaling pathways play important roles in the retina maintenance functions. Changes in intracellular Ca2+ concentration can be measured from living cells by Ca2+ imaging. Combining these measurements with quantitative analysis of Ca2+ response properties enables studies of signaling pathways affecting RPE functions. However, robust tools for response analysis from large cell populations are lacking. We developed MATLAB-based analysis tools for single cell level Ca2+ response data recorded from large fields of intact RPE monolayers. The analysis revealed significant heterogeneity in ATP-induced Ca2+ responses inside cell populations regarding magnitude and response kinetics. Further analysis including response grouping and parameter correlations allowed us to characterize the populations at the level of single cells.
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López E, Lee-Rivera I, Alvarez-Arce A, López-Colomé AM. Thrombin induces Ca 2+-dependent glutamate release from RPE cells mediated by PLC/PKC and reverse Na +/Ca 2+ exchange. Mol Vis 2019; 25:546-558. [PMID: 31673221 PMCID: PMC6798708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 10/03/2019] [Indexed: 11/01/2022] Open
Abstract
Purpose We analyzed the molecular mechanisms leading to glutamate release from rat primary cultures of RPE cells, under isosmotic conditions. Thrombin has been shown to stimulate glutamate release from astrocytes and retinal glia; however, the effect of thrombin on glutamate release from RPE cells has not been examined. Our previous work showed that upon the alteration of the blood-retina barrier, the serine protease thrombin could contribute to the transformation, proliferation, and migration of RPE cells. In this condition, elevated extracellular glutamate causes neuronal loss in many retinal disorders, including glaucoma, ischemia, diabetic retinopathy, and inherited photoreceptor degeneration. Methods Primary cultures of rat RPE cells were preloaded with 1 µCi/ml 3H-glutamate in Krebs Ringer Bicarbonate (KRB) buffer for 30 min at 37 °C. Cells were rinsed and super-perfused with 1 ml/min KRB for 15 min. Stable release was reached at the 7th minute, and on the 8th minute, fresh KRB containing stimuli was added. Results This study showed for the first time that thrombin promotes specific, dose-dependent glutamate release from RPE cells, induced by the activation of protease-activated receptor 1 (PAR-1). This effect was found to depend on the Ca2+ increase mediated by the phospholipase C-β (PLC-β) and protein kinase C (PKC) pathways, as well as by the reverse activity of the Na+/Ca2+ exchanger. Conclusions Given the intimate contact of the RPE with the photoreceptor outer segments, diffusion of RPE-released glutamate could contribute to the excitotoxic death of retinal neurons, and the development of thrombin-induced eye pathologies.
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Mastrangelo M, Alfonsi C, Screpanti I, Masuelli L, Tavazzi B, Mei D, Giannotti F, Guerrini R, Leuzzi V. Broadening phenotype of adenylosuccinate lyase deficiency: A novel clinical pattern resembling neuronal ceroid lipofuscinosis. Mol Genet Metab Rep 2019; 21:100502. [PMID: 31467849 PMCID: PMC6713842 DOI: 10.1016/j.ymgmr.2019.100502] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 08/07/2019] [Accepted: 08/07/2019] [Indexed: 11/30/2022] Open
Abstract
We describe a 7-year-old boy presenting with a developmental encephalopathy, severe epilepsy, retinopathy with salt and pepper fundus, and ultrastructural skin alterations resembling a neuronal ceroid lipofuscinosis. Whole exome-sequencing detected biallelic variants in the ADSL gene (c.65C > T [p.(Ala22Val)] and c.340 T > C [p.(Tyr114His)]). The increase of SAICAR and S-Ado in blood and urine was consistent with the pattern of adenylosuccinate lyase deficiency (OMIM 103050). An unusual increase of AICAR, that was due to a residual ADSL enzyme activity of about 28%, was also detected. Neither salt and pepper retinopathy nor ultrastructural skin alterations had been reported in ADSL deficiency before. Impaired purinergic signaling inside the retina is probably involved in visual failure. Ultrastructural alterations in fibroblasts suggest a possible damage of autophagic processes, whose role in the pathogenesis of neurological dysfunction deserves further study.
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Affiliation(s)
- Mario Mastrangelo
- Division of Child Neurology and Infantile Psychiatry, Department of Human Neurosciences, Sapienza University of Rome, Rome, Italy
| | - Chiara Alfonsi
- Division of Child Neurology and Infantile Psychiatry, Department of Human Neurosciences, Sapienza University of Rome, Rome, Italy
| | | | - Laura Masuelli
- Department of Experimental Medicine, Sapienza University of Rome, Italy
| | - Barbara Tavazzi
- Institute of Biochemistry and Clinical Biochemistry Catholic University, Rome
- Fondazione Policlinico Universitario A. Gemelli IRCCS, Italy
| | - Davide Mei
- Neuroscience and Neurogenetics Excellence Centre, Children's Hospital Anna Meyer, Florence, Italy
| | - Flavia Giannotti
- Division of Child Neurology and Infantile Psychiatry, Department of Human Neurosciences, Sapienza University of Rome, Rome, Italy
| | - Renzo Guerrini
- Neuroscience and Neurogenetics Excellence Centre, Children's Hospital Anna Meyer, Florence, Italy
| | - Vincenzo Leuzzi
- Division of Child Neurology and Infantile Psychiatry, Department of Human Neurosciences, Sapienza University of Rome, Rome, Italy
- Corresponding author at: Division of Child Neurology and Infantile Psychiatry, Department of Human Neurosciences, Sapienza- University of Rome, Via dei Sabelli 108, 00141 Roma, Italy.
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16
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Ventura ALM, Dos Santos-Rodrigues A, Mitchell CH, Faillace MP. Purinergic signaling in the retina: From development to disease. Brain Res Bull 2018; 151:92-108. [PMID: 30458250 DOI: 10.1016/j.brainresbull.2018.10.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 09/14/2018] [Accepted: 10/23/2018] [Indexed: 02/07/2023]
Abstract
Retinal injuries and diseases are major causes of human disability involving vision impairment by the progressive and permanent loss of retinal neurons. During development, assembly of this tissue entails a successive and overlapping, signal-regulated engagement of complex events that include proliferation of progenitors, neurogenesis, cell death, neurochemical differentiation and synaptogenesis. During retinal damage, several of these events are re-activated with both protective and detrimental consequences. Purines and pyrimidines, along with their metabolites are emerging as important molecules regulating both retinal development and the tissue's responses to damage. The present review provides an overview of the purinergic signaling in the developing and injured retina. Recent findings on the presence of vesicular and channel-mediated ATP release by retinal and retinal pigment epithelial cells, adenosine synthesis and release, expression of receptors and intracellular signaling pathways activated by purinergic signaling in retinal cells are reported. The pathways by which purinergic receptors modulate retinal cell proliferation, migration and death of retinal cells during development and injury are summarized. The contribution of nucleotides to the self-repair of the injured zebrafish retina is also discussed.
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Affiliation(s)
- Ana Lucia Marques Ventura
- Department of Neurobiology, Neuroscience Program, Fluminense Federal University, Niterói, RJ, Brazil.
| | | | - Claire H Mitchell
- Department of Anatomy and Cell Biology, Ophthalmology, and Physiology, University of Pennsylvania, Philadelphia, PA 19104, United States.
| | - Maria Paula Faillace
- Instituto de Fisiología y Biofísica Prof. Bernardo Houssay (IFIBIO-Houssay), Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina; Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.
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17
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Soliño M, Larrayoz IM, López EM, Vacotto M, Martignone N, Rey-Funes M, Martínez A, Girardi E, López-Costa JJ. The expression of adenosine receptors changes throughout light induced retinal degeneration in the rat. Neurosci Lett 2018; 687:259-267. [PMID: 30291879 DOI: 10.1016/j.neulet.2018.09.053] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 09/18/2018] [Accepted: 09/26/2018] [Indexed: 01/24/2023]
Abstract
The modulation of adenosine receptors, A1 (A1R) and A2A (A2AR), is neuroprotective in different models of retinal injury. In order to understand the processes underlying retinal degeneration, we studied the expression of adenosine receptors in the retinas of control and continuously illuminated (CI) rats by qRT-PCR, Western blot (WB) and immunohistochemistry (IHC). Significant increases of A1R, A2AR, and A2BR mRNAs at 1, 5, and 7 days of CI (P < 0.0001) were observed by qRT-PCR. Also, a significant increase of A3R mRNA was detected after 5 and 7 days of CI. WB studies showed a significant rise of A1R on day 1 of CI and on days 5 and 7 (P < 0.0001), while A2AR increase was seen from 2 days of CI on (P < 0.001). After 1 day of CI, A1R immunoreactivity (A1R-IR) increased in ganglion cell layer, inner nuclear layer, and in both the outer and inner plexiform layers. After 2 days of CI, the A1R-IR went back to control levels. After 5 days of CI, a second rise in A1R, which persisted until 7 days of CI, was measured (P < 0.0001). A significant rise of A2aR immunoreactivity was also observed at day 2 of CI at GCL and INL and subsided at days 5 and 7 (P < 0.0001). The observed up-regulation of A1R after 1 day of CI, corresponds with the peak of oxidative stress; while the rise of A2aR at day 2 of CI, coincides with the massive apoptosis of photoreceptors. We postulate that an early modulation of adenosine receptors could delay or prevent the degeneration of photoreceptors.
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Affiliation(s)
- Manuel Soliño
- Universidad de Buenos Aires, Facultad de Medicina, Dpto. de Biología Celular, Histología, Embriología y Genética, Ciudad Autónoma de Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Biología Celular y Neurociencia "Prof. E. De Robertis¨ (IBCN), Ciudad Autónoma de Buenos Aires, Argentina
| | - Ignacio M Larrayoz
- Biomarkers and Molecular Signaling Group, Center for Biomedical Research of La Rioja (CIBIR), Logroño, Spain
| | - Ester M López
- Universidad de Buenos Aires, Facultad de Medicina, Dpto. de Biología Celular, Histología, Embriología y Genética, Ciudad Autónoma de Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Biología Celular y Neurociencia "Prof. E. De Robertis¨ (IBCN), Ciudad Autónoma de Buenos Aires, Argentina
| | - Marina Vacotto
- Universidad de Buenos Aires, Facultad de Medicina, Dpto. de Biología Celular, Histología, Embriología y Genética, Ciudad Autónoma de Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Biología Celular y Neurociencia "Prof. E. De Robertis¨ (IBCN), Ciudad Autónoma de Buenos Aires, Argentina
| | - Noelí Martignone
- Universidad de Buenos Aires, Facultad de Medicina, Dpto. de Biología Celular, Histología, Embriología y Genética, Ciudad Autónoma de Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Biología Celular y Neurociencia "Prof. E. De Robertis¨ (IBCN), Ciudad Autónoma de Buenos Aires, Argentina
| | - Manuel Rey-Funes
- Universidad de Buenos Aires, Facultad de Medicina, Dpto. de Biología Celular, Histología, Embriología y Genética, Ciudad Autónoma de Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Biología Celular y Neurociencia "Prof. E. De Robertis¨ (IBCN), Ciudad Autónoma de Buenos Aires, Argentina
| | - Alfredo Martínez
- Angiogenesis Study Group, Center for Biomedical Research of La Rioja (CIBIR), 26006 Logroño, Spain
| | - Elena Girardi
- Universidad de Buenos Aires, Facultad de Medicina, Dpto. de Biología Celular, Histología, Embriología y Genética, Ciudad Autónoma de Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Biología Celular y Neurociencia "Prof. E. De Robertis¨ (IBCN), Ciudad Autónoma de Buenos Aires, Argentina
| | - Juan J López-Costa
- Universidad de Buenos Aires, Facultad de Medicina, Dpto. de Biología Celular, Histología, Embriología y Genética, Ciudad Autónoma de Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Biología Celular y Neurociencia "Prof. E. De Robertis¨ (IBCN), Ciudad Autónoma de Buenos Aires, Argentina.
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Beckel JM, Gómez NM, Lu W, Campagno KE, Nabet B, Albalawi F, Lim JC, Boesze-Battaglia K, Mitchell CH. Stimulation of TLR3 triggers release of lysosomal ATP in astrocytes and epithelial cells that requires TRPML1 channels. Sci Rep 2018; 8:5726. [PMID: 29636491 PMCID: PMC5893592 DOI: 10.1038/s41598-018-23877-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 03/16/2018] [Indexed: 01/25/2023] Open
Abstract
Cross-reactions between innate immunity, lysosomal function, and purinergic pathways may link signaling systems in cellular pathologies. We found activation of toll-like receptor 3 (TLR3) triggers lysosomal ATP release from both astrocytes and retinal pigmented epithelial (RPE) cells. ATP efflux was accompanied by lysosomal acid phosphatase and beta hexosaminidase release. Poly(I:C) alkalinized lysosomes, and lysosomal alkalization with bafilomycin or chloroquine triggered ATP release. Lysosomal rupture with glycyl-L-phenylalanine-2-naphthylamide (GPN) eliminated both ATP and acid phosphatase release. Secretory lysosome marker LAMP3 colocalized with VNUT, while MANT-ATP colocalized with LysoTracker. Unmodified membrane-impermeant 21-nt and "non-targeting" scrambled 21-nt siRNA triggered ATP and acid phosphatase release, while smaller 16-nt RNA was ineffective. Poly(I:C)-dependent ATP release was reduced by TBK-1 block and in TRPML1-/- cells, while TRPML activation with ML-SA1 was sufficient to release both ATP and acid phosphatase. The ability of poly(I:C) to raise cytoplasmic Ca2+ was abolished by removing extracellular ATP with apyrase, suggesting ATP release by poly(I:C) increased cellular signaling. Starvation but not rapamycin prevented lysosomal ATP release. In summary, stimulation of TLR3 triggers lysosomal alkalization and release of lysosomal ATP through activation of TRPML1; this links innate immunity to purinergic signaling via lysosomal physiology, and suggests even scrambled siRNA can influence these pathways.
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Affiliation(s)
- Jonathan M Beckel
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, PA, USA
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Néstor Más Gómez
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - Wennan Lu
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - Keith E Campagno
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - Bardia Nabet
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - Farraj Albalawi
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, PA, USA
- Department of Orthodontics, University of Pennsylvania, Philadelphia, PA, USA
| | - Jason C Lim
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, PA, USA
| | | | - Claire H Mitchell
- Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, PA, USA.
- Department of Ophthalmology, University of Pennsylvania, Philadelphia, PA, USA.
- Department of Physiology, University of Pennsylvania, Philadelphia, PA, USA.
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Purinergic modulation of frog electroretinographic responses: The role of the ionotropic receptor P2X7. Vis Neurosci 2018; 34:E015. [PMID: 28965497 DOI: 10.1017/s0952523817000128] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The contribution of the purinergic receptors P2X7 (P2X7Rs) to the electroretinographic (ERG) responses was studied by testing the effects of the selective P2X7R antagonist A438079 and the selective P2X7R agonist Bz-ATP on the electroretinograms obtained in perfused frog (Rana ridibunda) eyecup preparations under a variety of stimulation conditions. The P2X7R blockade by 200 µM A438079 diminished the amplitude of the photoreceptor components: the a-wave and the pharmacologically isolated mass receptor potential. In the pure rod-driven and pure cone-driven responses, the amplitude of the postreceptoral ON (b-wave) and OFF (d-wave) components was also diminished. The OFF responses were affected to a greater extent compared to the ON responses. In the mixed rod- and cone-driven responses, obtained in the mesopic intensity range, the b-wave amplitude was increased, while the d-wave amplitude was decreased. The amplitude of the oscillatory potentials was diminished. The relative amplitude changes produced by the P2X7R blockade were greater in the dark-adapted compared to the light-adapted eyes. The application of 100 µM Bz-ATP produced small effects opposite to those of the antagonist, while a prolonged (>20 min) treatment with 1 mM Bz-ATP resulted in a significant amplitude reduction or even abolishment of b- and d-waves. Our results show that endogenous ATP through its P2X7Rs exerts significant, mostly potentiating effects on the ERG photoreceptor and postreceptoral responses. There is a clear ON/OFF asymmetry of the effects on the ERG postreceptoral responses favoring OFF responses: they are always strongly potentiated, while the ON responses are either less potentiated (in the rod-driven and most of the cone-driven responses) or even inhibited (in the mixed rod- and cone-driven responses). The overstimulation of P2X7Rs can produce acute pathological changes, that is, a decrease or abolishment of the ERG responses.
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Mancini JE, Ortiz G, Potilinstki C, Salica JP, Lopez ES, Croxatto JO, Gallo JE. Possible neuroprotective role of P2X2 in the retina of diabetic rats. Diabetol Metab Syndr 2018; 10:31. [PMID: 29682007 PMCID: PMC5898034 DOI: 10.1186/s13098-018-0332-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 04/04/2018] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Purinergic receptors are expressed in different tissues including the retina. These receptors are involved in processes like cell growth, proliferation, activation and survival. ATP is the major activator of P2 receptors. In diabetes, there is a constant ATP production and this rise of ATP leads to a persistent activation of purinergic receptors. Antagonists of these receptors are used to evaluate their inhibition effects. Recently, the P2X2 has been reported to have a neuroprotective role. METHODS We carried out a study in groups of diabetic and non-diabetic rats (N = 5) treated with intraperitoneal injections of PPADS, at 9 and 24 weeks of diabetes. Control group received only the buffer. Animals were euthanized at 34 weeks of diabetes or at a matching age. Rat retinas were analyzed with immunohistochemistry and western blot using antibodies against GFAP, P2X2, P2Y2 and VEGF-A. RESULTS Diabetic animals treated with PPADS disclosed a much more extended staining of VEGF-A than diabetics without treatment. A lower protein expression of VEGF-A was found at the retina of diabetic animals without treatment of purinergic antagonists compared to diabetics with the antagonist treatment. Inhibition of P2X2 receptor by PPADS decreases cell death in the diabetic rat retina. CONCLUSION Results might be useful for better understanding the pathophysiology of diabetic retinopathy.
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Affiliation(s)
- Jorge E. Mancini
- Department of Ophthalmology, Nanomedicine & Vision Group, Facultad de Ciencias Biomédicas, Universidad Austral, Av. Juan D. Perón 1500, B1629AHJ Pilar, Buenos Aires Argentina
- Instituto de Investigaciones en Medicina Traslacional (IIMT), Universidad Austral, Consejo Nacional de Investigaciones Científicas y Técnicas (UA-CONICET), Pilar, Buenos Aires, Argentina
| | - Gustavo Ortiz
- Department of Ophthalmology, Nanomedicine & Vision Group, Facultad de Ciencias Biomédicas, Universidad Austral, Av. Juan D. Perón 1500, B1629AHJ Pilar, Buenos Aires Argentina
- Instituto de Investigaciones en Medicina Traslacional (IIMT), Universidad Austral, Consejo Nacional de Investigaciones Científicas y Técnicas (UA-CONICET), Pilar, Buenos Aires, Argentina
| | - Constanza Potilinstki
- Department of Ophthalmology, Nanomedicine & Vision Group, Facultad de Ciencias Biomédicas, Universidad Austral, Av. Juan D. Perón 1500, B1629AHJ Pilar, Buenos Aires Argentina
- Instituto de Investigaciones en Medicina Traslacional (IIMT), Universidad Austral, Consejo Nacional de Investigaciones Científicas y Técnicas (UA-CONICET), Pilar, Buenos Aires, Argentina
| | - Juan P. Salica
- Department of Ophthalmology, Nanomedicine & Vision Group, Facultad de Ciencias Biomédicas, Universidad Austral, Av. Juan D. Perón 1500, B1629AHJ Pilar, Buenos Aires Argentina
- Instituto de Investigaciones en Medicina Traslacional (IIMT), Universidad Austral, Consejo Nacional de Investigaciones Científicas y Técnicas (UA-CONICET), Pilar, Buenos Aires, Argentina
| | - Emiliano S. Lopez
- Department of Ophthalmology, Nanomedicine & Vision Group, Facultad de Ciencias Biomédicas, Universidad Austral, Av. Juan D. Perón 1500, B1629AHJ Pilar, Buenos Aires Argentina
- Instituto de Investigaciones en Medicina Traslacional (IIMT), Universidad Austral, Consejo Nacional de Investigaciones Científicas y Técnicas (UA-CONICET), Pilar, Buenos Aires, Argentina
| | - J. Oscar Croxatto
- Department of Ocular Pathology, Fundación Oftalmlógica Argentina “Jorge Malbran”, Buenos Aires, Argentina
- Instituto de Investigaciones en Medicina Traslacional (IIMT), Universidad Austral, Consejo Nacional de Investigaciones Científicas y Técnicas (UA-CONICET), Pilar, Buenos Aires, Argentina
| | - Juan E. Gallo
- Department of Ophthalmology, Nanomedicine & Vision Group, Facultad de Ciencias Biomédicas, Universidad Austral, Av. Juan D. Perón 1500, B1629AHJ Pilar, Buenos Aires Argentina
- Instituto de Investigaciones en Medicina Traslacional (IIMT), Universidad Austral, Consejo Nacional de Investigaciones Científicas y Técnicas (UA-CONICET), Pilar, Buenos Aires, Argentina
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Ma W, Zhang Y, Gao C, Fariss RN, Tam J, Wong WT. Monocyte infiltration and proliferation reestablish myeloid cell homeostasis in the mouse retina following retinal pigment epithelial cell injury. Sci Rep 2017; 7:8433. [PMID: 28814744 PMCID: PMC5559448 DOI: 10.1038/s41598-017-08702-7] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 07/13/2017] [Indexed: 02/07/2023] Open
Abstract
Age-related macular degeneration (AMD), a leading contributor of vision loss, currently lacks comprehensive treatment. While AMD histopathology involves retinal pigment epithelium (RPE) injury associated with immune cell infiltration, the nature of immune cell responses to RPE injury remains undefined. We induced RPE injury pharmacologically and genetically in transgenic mouse models in which microglia and systemic monocytes were separately tagged, enabling a spatial and temporal dissection of the relative contributions of microglia vs. monocytes to post-injury changes. We found that myeloid cell responses to RPE injury occur in stages: (1) an early mobilization of endogenous microglia from the inner retina to the RPE layer, followed by (2) subsequent monocyte infiltration from the retinal vasculature into the inner retina that replenishes the local myeloid cell population in a CCR2-regulated manner. These altered distributions of myeloid cells post-injury were long-lived, with recruited monocytes acquiring the distribution, markers, and morphologies of neighboring endogenous microglia in a durable manner. These findings indicate the role played by infiltrating monocytes in maintaining myeloid cell homeostasis in the retina following AMD-relevant RPE injury and provide a foundation for understanding and therapeutically modulating immune aspects in retinal disease.
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Affiliation(s)
- Wenxin Ma
- Unit on Neuron-Glia Interactions in Retinal Disease, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Yikui Zhang
- Unit on Neuron-Glia Interactions in Retinal Disease, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Chun Gao
- Biological Imaging Core, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Robert N Fariss
- Biological Imaging Core, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Johnny Tam
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Wai T Wong
- Unit on Neuron-Glia Interactions in Retinal Disease, National Institutes of Health, Bethesda, MD, 20892, USA.
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Crooke A, Guzman-Aranguez A, Carracedo G, de Lara MJP, Pintor J. Understanding the Presence and Roles of Ap 4A (Diadenosine Tetraphosphate) in the Eye. J Ocul Pharmacol Ther 2017; 33:426-434. [PMID: 28414592 DOI: 10.1089/jop.2016.0146] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Diadenosine tetraphosphate abbreviated Ap4A is a naturally occurring dinucleotide, which is present in most of the ocular fluids. Due to its intrinsic resistance to enzyme degradation compared to mononucleotides, this molecule can exhibit profound actions on ocular tissues, including the ocular surface, ciliary body, trabecular meshwork, and probably the retina. The actions of Ap4A are mostly carried out by P2Y2 receptors, but the participation of P2X2 and P2Y6 in processes such as the regulation of intraocular pressure (IOP), together with the P2Y2, is pivotal. Beyond the physiological role, this dinucleotide can present on the ocular surface keeping a right production of tear secretion or regulating IOP. It is important to note that exogenous application of Ap4A to cells or animal models can significantly modify pathophysiological conditions and thus is an attractive therapeutic molecule. The ocular location where Ap4A actions have not been fully elucidated is in the retina. Although some analogues show interesting actions on pathological situations such as retinal detachment, little is known about the real effect of this dinucleotide, this being one of the challenges that require pursuing in the near future.
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Affiliation(s)
- Almudena Crooke
- 1 Departamento de Bioquímica y Biología Molecular, Universidad Complutense de Madrid , Madrid, Spain
| | - Ana Guzman-Aranguez
- 1 Departamento de Bioquímica y Biología Molecular, Universidad Complutense de Madrid , Madrid, Spain
| | - Gonzalo Carracedo
- 2 Departamento de Optometría y Visión, F. Óptica, Universidad Complutense de Madrid , Madrid, Spain
| | - Maria J Perez de Lara
- 1 Departamento de Bioquímica y Biología Molecular, Universidad Complutense de Madrid , Madrid, Spain
| | - Jesus Pintor
- 1 Departamento de Bioquímica y Biología Molecular, Universidad Complutense de Madrid , Madrid, Spain
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Moriyama S, Hiasa M. Expression of Vesicular Nucleotide Transporter in the Mouse Retina. Biol Pharm Bull 2017; 39:564-9. [PMID: 27040629 DOI: 10.1248/bpb.b15-00872] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Vesicular nucleotide transporter (VNUT) is a membrane protein that is responsible for vesicular storage and subsequent vesicular release of nucleotides, such as ATP, and plays an essential role in purinergic chemical transmission. In the present study, we investigated whether VNUT is present in the rodent retina to define the site(s) of vesicular ATP release. In the mouse retina, reverse transcription polymerase chain reaction (RT-PCR) and immunological analyses using specific anti-VNUT antibodies indicated that VNUT is expressed as a polypeptide with an apparent molecular mass of 59 kDa. VNUT is widely distributed throughout the inner and outer retinal layers, particularly in the outer segment of photoreceptors, outer plexiform layer, inner plexiform layer, and ganglion cell layer. VNUT is colocalized with vesicular glutamate transporter 1 and synaptophysin in photoreceptor cells, while it is colocalized with vesicular γ-aminobutyric acid (GABA) transporter in amacrine cells and bipolar cells. VNUT is also present in astrocytes and Müller cells. The retina from VNUT knockout (VNUT(-/-)) mice showed the loss of VNUT immunoreactivity. The retinal membrane fraction took up radiolabeled ATP in diisothiocyanate stilbene disulfonic acid (DIDS)-, an inhibitor of VNUT, and bafilomycin A1-, a vacuolar adenosine triphosphatase (ATPase) inhibitor, in a sensitive manner, while membranes from VNUT(-/-) mice showed the loss of DIDS-sensitive ATP uptake. Taken together, these results indicate that functional VNUT is expressed in the rodent retina and suggest that ATP is released from photoreceptor cells, bipolar cells, amacrine cells, and astrocytes as well as Müller cells to initiate purinergic chemical transmission.
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Affiliation(s)
- Satomi Moriyama
- Department of Membrane Biochemistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences
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Ho T, Aplin FP, Jobling AI, Phipps JA, de Iongh RU, Greferath U, Vessey KA, Fletcher EL. Localization and Possible Function of P2X Receptors in Normal and Diseased Retinae. J Ocul Pharmacol Ther 2016; 32:509-517. [DOI: 10.1089/jop.2015.0158] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Affiliation(s)
- Tracy Ho
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Australia
| | - Felix P. Aplin
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Australia
| | - Andrew I. Jobling
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Australia
| | - Joanna A. Phipps
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Australia
| | - Robb U. de Iongh
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Australia
| | - Ursula Greferath
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Australia
| | - Kirstan A. Vessey
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Australia
| | - Erica L. Fletcher
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Australia
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25
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Miyagishima KJ, Wan Q, Corneo B, Sharma R, Lotfi MR, Boles NC, Hua F, Maminishkis A, Zhang C, Blenkinsop T, Khristov V, Jha BS, Memon OS, D'Souza S, Temple S, Miller SS, Bharti K. In Pursuit of Authenticity: Induced Pluripotent Stem Cell-Derived Retinal Pigment Epithelium for Clinical Applications. Stem Cells Transl Med 2016; 5:1562-1574. [PMID: 27400791 PMCID: PMC5070511 DOI: 10.5966/sctm.2016-0037] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 04/18/2016] [Indexed: 12/12/2022] Open
Abstract
For effective treatment, induced pluripotent stem cell (iPSC)-retinal pigment epithelium (RPE) must recapitulate the physiology of native human RPE cells. A set of physiologically relevant functional assays that assess the polarized functional activity and maturation state of the intact RPE monolayer is provided. The study data show that donor-to-donor variability exceeds the tissue-to-tissue variability for a given donor and provides, for the first time, criteria necessary to identify iPSC-RPE cells most suitable for clinical application. Induced pluripotent stem cells (iPSCs) can be efficiently differentiated into retinal pigment epithelium (RPE), offering the possibility of autologous cell replacement therapy for retinal degeneration stemming from RPE loss. The generation and maintenance of epithelial apical-basolateral polarity is fundamental for iPSC-derived RPE (iPSC-RPE) to recapitulate native RPE structure and function. Presently, no criteria have been established to determine clonal or donor based heterogeneity in the polarization and maturation state of iPSC-RPE. We provide an unbiased structural, molecular, and physiological evaluation of 15 iPSC-RPE that have been derived from distinct tissues from several different donors. We assessed the intact RPE monolayer in terms of an ATP-dependent signaling pathway that drives critical aspects of RPE function, including calcium and electrophysiological responses, as well as steady-state fluid transport. These responses have key in vivo counterparts that together help determine the homeostasis of the distal retina. We characterized the donor and clonal variation and found that iPSC-RPE function was more significantly affected by the genetic differences between different donors than the epigenetic differences associated with different starting tissues. This study provides a reference dataset to authenticate genetically diverse iPSC-RPE derived for clinical applications. Significance The retinal pigment epithelium (RPE) is essential for maintaining visual function. RPE derived from human induced pluripotent stem cells (iPSC-RPE) offer a promising cell-based transplantation therapy for slowing or rescuing RPE-induced visual function loss. For effective treatment, iPSC-RPE must recapitulate the physiology of native human RPE. A set of physiologically relevant functional assays are provided that assess the polarized functional activity and maturation state of the intact RPE monolayer. The present data show that donor-to-donor variability exceeds the tissue-to-tissue variability for a given donor and provides, for the first time, criteria necessary to identify iPSC-RPE most suitable for clinical application.
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Affiliation(s)
- Kiyoharu J Miyagishima
- Section on Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Qin Wan
- Section on Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Barbara Corneo
- Columbia Stem Cell Core Facility, Columbia University Medical Center, New York, New York, USA
| | - Ruchi Sharma
- Unit on Ocular and Stem Cell Translational Research, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Mostafa R Lotfi
- Section on Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | | | - Fang Hua
- Section on Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Arvydas Maminishkis
- Section on Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Congxiao Zhang
- Section on Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Timothy Blenkinsop
- Department of Development and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Vladimir Khristov
- Section on Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Balendu S Jha
- Unit on Ocular and Stem Cell Translational Research, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Omar S Memon
- Section on Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Sunita D'Souza
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Sally Temple
- Neural Stem Cell Institute, Rensselaer, New York, USA
| | - Sheldon S Miller
- Section on Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Kapil Bharti
- Unit on Ocular and Stem Cell Translational Research, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
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26
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Aplin FP, Vessey KA, Luu CD, Guymer RH, Shepherd RK, Fletcher EL. Retinal Changes in an ATP-Induced Model of Retinal Degeneration. Front Neuroanat 2016; 10:46. [PMID: 27199678 PMCID: PMC4850166 DOI: 10.3389/fnana.2016.00046] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 04/11/2016] [Indexed: 11/20/2022] Open
Abstract
In rodents and felines, intravitreal administration of adenosine triphosphate (ATP) has been shown to induce photoreceptor death providing a tractable model of retinal degeneration in these species. This study investigated the long term effects of photoreceptor loss in an ATP induced feline model of retinal degeneration. Six normal sighted felines were unilaterally blinded using intravitreal ATP injections and assessed using electroretinography (ERG) and optical coherence tomography (OCT). At 30 h (n = 3) or 12 weeks (n = 3) post-injection, the animals were euthanized and the eyes enucleated. Retinae were sectioned and labeled using immunohistochemistry for markers of cell death, neural remodeling and gliosis. Ongoing cell death and retinal degeneration was observed in the outer retina at both 30 h and 12 weeks following unilateral ATP injection. Markers of mid to late-stage retinal remodeling such as cell displacement and aberrant neurite growth were observed in the inner retina at 12 weeks post-injection. Ganglion cells appeared to remain intact in ATP injected eyes. Müller cell gliosis was observed throughout the inner and outer retina, in some parts completely enveloping and/or displacing the surviving neural tissue. Our data suggests that the ATP injected feline retina continues to undergo progressive retinal degeneration and exhibits abnormalities consistent with a description of retinal remodeling commonly seen in other models of retinal degeneration. These findings validate the use of intravitreal ATP injection in feline as a large animal model of retinal degeneration which may aid in development of therapies aiming to restore visual function after photoreceptor degeneration.
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Affiliation(s)
- Felix P Aplin
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East MelbourneMelbourne, VIC, Australia; Department of Anatomy and Neuroscience, The University of MelbourneMelbourne, VIC, Australia; The Bionics Institute, East MelbourneMelbourne, VIC, Australia
| | - Kirstan A Vessey
- Department of Anatomy and Neuroscience, The University of Melbourne Melbourne, VIC, Australia
| | - Chi D Luu
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East MelbourneMelbourne, VIC, Australia; Department of Surgery (Ophthalmology), The University of MelbourneParkville, VIC, Australia
| | - Robyn H Guymer
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East MelbourneMelbourne, VIC, Australia; Department of Surgery (Ophthalmology), The University of MelbourneParkville, VIC, Australia
| | - Robert K Shepherd
- The Bionics Institute, East MelbourneMelbourne, VIC, Australia; Medical Bionics Department, The University of MelbourneMelbourne, VIC, Australia
| | - Erica L Fletcher
- Department of Anatomy and Neuroscience, The University of Melbourne Melbourne, VIC, Australia
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27
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Reichenbach A, Bringmann A. Purinergic signaling in retinal degeneration and regeneration. Neuropharmacology 2015; 104:194-211. [PMID: 25998275 DOI: 10.1016/j.neuropharm.2015.05.005] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 05/07/2015] [Accepted: 05/07/2015] [Indexed: 02/01/2023]
Abstract
Purinergic signaling is centrally involved in mediating the degeneration of the injured and diseased retina, the induction of retinal gliosis, and the protection of the retinal tissue from degeneration. Dysregulated calcium signaling triggered by overactivation of P2X7 receptors is a crucial step in the induction of neuronal and microvascular cell death under pathogenic conditions like ischemia-hypoxia, elevated intraocular pressure, and diabetes, respectively. Overactivation of P2X7 plays also a pathogenic role in inherited and age-related photoreceptor cell death and in the age-related dysfunction and degeneration of the retinal pigment epithelium. Gliosis of micro- and macroglial cells, which is induced and/or modulated by purinergic signaling and associated with an impaired homeostatic support to neurons, and the ATP-mediated propagation of retinal gliosis from a focal injury into the surrounding noninjured tissue are involved in inducing secondary cell death in the retina. On the other hand, alterations in the glial metabolism of extracellular nucleotides, resulting in a decreased level of ATP and an increased level of adenosine, may be neuroprotective in the diseased retina. Purinergic signals stimulate the proliferation of retinal glial cells which contributes to glial scarring which has protective effects on retinal degeneration and adverse effects on retinal regeneration. Pharmacological modulation of purinergic receptors, e.g., inhibition of P2X and activation of adenosine receptors, may have clinical importance for the prevention of photoreceptor, neuronal, and microvascular cell death in diabetic retinopathy, retinitis pigmentosa, age-related macular degeneration, and glaucoma, respectively, for the clearance of retinal edema, and the inhibition of dysregulated cell proliferation in proliferative retinopathies. This article is part of a Special Issue entitled 'Purines in Neurodegeneration and Neuroregeneration'.
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Affiliation(s)
- Andreas Reichenbach
- Paul Flechsig Institute of Brain Research, University of Leipzig, Leipzig, Germany.
| | - Andreas Bringmann
- Department of Ophthalmology and Eye Hospital, University of Leipzig, Leipzig, Germany
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28
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Ou Y, Wu J, Sandberg M, Weber SG. Electroosmotic perfusion of tissue: sampling the extracellular space and quantitative assessment of membrane-bound enzyme activity in organotypic hippocampal slice cultures. Anal Bioanal Chem 2014; 406:6455-68. [PMID: 25168111 DOI: 10.1007/s00216-014-8067-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2014] [Revised: 07/18/2014] [Accepted: 07/25/2014] [Indexed: 01/30/2023]
Abstract
This review covers recent advances in sampling fluid from the extracellular space of brain tissue by electroosmosis (EO). Two techniques, EO sampling with a single fused-silica capillary and EO push-pull perfusion, have been developed. These tools were used to investigate the function of membrane-bound enzymes with outward-facing active sites, or ectoenzymes, in modulating the activity of the neuropeptides leu-enkephalin and galanin in organotypic-hippocampal-slice cultures (OHSCs). In addition, the approach was used to determine the endogenous concentration of a thiol, cysteamine, in OHSCs. We have also investigated the degradation of coenzyme A in the extracellular space. The approach provides information on ectoenzyme activity, including Michaelis constants, in tissue, which, as far as we are aware, has not been done before. On the basis of computational evidence, EO push-pull perfusion can distinguish ectoenzyme activity with a ~100 μm spatial resolution, which is important for studies of enzyme kinetics in adjacent regions of the rat hippocampus.
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Affiliation(s)
- Yangguang Ou
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, 15260, USA
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29
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Sanderson J, Dartt DA, Trinkaus-Randall V, Pintor J, Civan MM, Delamere NA, Fletcher EL, Salt TE, Grosche A, Mitchell CH. Purines in the eye: recent evidence for the physiological and pathological role of purines in the RPE, retinal neurons, astrocytes, Müller cells, lens, trabecular meshwork, cornea and lacrimal gland. Exp Eye Res 2014; 127:270-9. [PMID: 25151301 DOI: 10.1016/j.exer.2014.08.009] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 07/24/2014] [Accepted: 08/12/2014] [Indexed: 12/21/2022]
Abstract
This review highlights recent findings that describ how purines modulate the physiological and pathophysiological responses of ocular tissues. For example, in lacrimal glands the cross-talk between P2X7 receptors and both M3 muscarinic receptors and α1D-adrenergic receptors can influence tear secretion. In the cornea, purines lead to post-translational modification of EGFR and structural proteins that participate in wound repair in the epithelium and influence the expression of matrix proteins in the stroma. Purines act at receptors on both the trabecular meshwork and ciliary epithelium to modulate intraocular pressure (IOP); ATP-release pathways of inflow and outflow cells differ, possibly permitting differential modulation of adenosine delivery. Modulators of trabecular meshwork cell ATP release include cell volume, stretch, extracellular Ca(2+) concentration, oxidation state, actin remodeling and possibly endogenous cardiotonic steroids. In the lens, osmotic stress leads to ATP release following TRPV4 activation upstream of hemichannel opening. In the anterior eye, diadenosine polyphosphates such as Ap4A act at P2 receptors to modulate the rate and composition of tear secretion, impact corneal wound healing and lower IOP. The Gq11-coupled P2Y1-receptor contributes to volume control in Müller cells and thus the retina. P2X receptors are expressed in neurons in the inner and outer retina and contribute to visual processing as well as the demise of retinal ganglion cells. In RPE cells, the balance between extracellular ATP and adenosine may modulate lysosomal pH and the rate of lipofuscin formation. In optic nerve head astrocytes, mechanosensitive ATP release via pannexin hemichannels, coupled with stretch-dependent upregulation of pannexins, provides a mechanism for ATP signaling in chronic glaucoma. With so many receptors linked to divergent functions throughout the eye, ensuring the transmitters remain local and stimulation is restricted to the intended target may be a key issue in understanding how physiological signaling becomes pathological in ocular disease.
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Affiliation(s)
| | - Darlene A Dartt
- Schepens Eye Research Institute/Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Vickery Trinkaus-Randall
- Department of Ophthalmology, Boston University School of Medicine, Boston, MA, USA; Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA
| | - Jesus Pintor
- Department of Biochemistry, Faculty of Optometry, Universidad Complutense de Madrid, Madrid, Spain
| | - Mortimer M Civan
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; Department of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Nicholas A Delamere
- Department of Physiology, University of Arizona, Tucson, AZ, USA; Department of Ophthalmology and Vision Science, University of Arizona, Tucson, AZ, USA
| | - Erica L Fletcher
- Department of Anatomy and of Neuroscience, University of Melbourne, Victoria, Australia
| | - Thomas E Salt
- Department of Visual Neuroscience, UCL Institute of Ophthalmology, London, UK
| | - Antje Grosche
- Institute of Human Genetics, Franz-Josef-Strauß-Allee, Regensburg, Germany
| | - Claire H Mitchell
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; Department of Anatomy and Cell Biology, University of Pennsylvania, Philadelphia, PA, USA.
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30
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Vitanova LA, Kupenova PN. Ionotropic purinergic receptors P2X in frog and turtle retina: glial and neuronal localization. Acta Histochem 2014; 116:694-701. [PMID: 24461518 DOI: 10.1016/j.acthis.2013.12.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Revised: 12/12/2013] [Accepted: 12/16/2013] [Indexed: 12/15/2022]
Abstract
Purinergic signaling is represented in both the peripheral and central nervous system (CNS), and in particular in the retina, which may be regarded as a part of the CNS. While purigenic signaling is relatively well studied in mammalian retinas, little is known about it in retinas of lower vertebrates. The aim of present study was to investigate, using immunocytochemistry, the distribution of purinoreceptors P2X in retinas of frog and turtle, which are appropriate models of the brain neuron-to-glia interactions. The results showed widespread expression of all seven ionotropic purinoreceptors (P2X1-P2X7) in both frog and turtle retinas. They were predominantly expressed in Müller cells, the principal glial cells in the retina. All structures typical of Müller cells: the outer and the inner limiting membranes, the cells bodies in the inner nuclear layer, the radial processes in the inner plexiform layer (IPL), and the so called endfeet (frog) or the orthogonal arrays of particles (turtle) in the ganglion cells layer were immunostained. Colocalizations between P2X1-P2X7 and the glial cell marker Vimentin proved that the immunostaining was in the Müller cells. In addition to the glial staining, neuronal staining was also seen as fine puncta in the inner plexiform layer and by small dots and patches in the outer plexiform layer. Some cell bodies of horizontal, amacrine and ganglion cells were also stained. The results obtained imply that the purinergic P2X receptors may significantly contribute to the neuron-to-glia signaling in retinas of the lower vertebrates.
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31
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Guha S, Baltazar GC, Coffey EE, Tu LA, Lim JC, Beckel JM, Patel S, Eysteinsson T, Lu W, O'Brien-Jenkins A, Laties AM, Mitchell CH. Lysosomal alkalinization, lipid oxidation, and reduced phagosome clearance triggered by activation of the P2X7 receptor. FASEB J 2013; 27:4500-9. [PMID: 23964074 DOI: 10.1096/fj.13-236166] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Lysosomal enzymes function optimally at low pH; as accumulation of waste material contributes to cell aging and disease, dysregulation of lysosomal pH may represent an early step in several pathologies. Here, we demonstrate that stimulation of the P2X7 receptor (P2X7R) for ATP alkalinizes lysosomes in cultured human retinal pigmented epithelial (RPE) cells and impairs lysosomal function. P2X7R stimulation did not kill RPE cells but alkalinized lysosomes by 0.3 U. Receptor stimulation also elevated cytoplasmic Ca(2+); Ca(2+) influx was necessary but not sufficient for lysosomal alkalinization. P2X7R stimulation decreased access to the active site of cathepsin D. Interestingly, lysosomal alkalinization was accompanied by a rise in lipid oxidation that was prevented by P2X7R antagonism. Likewise, the autofluorescence of phagocytosed photoreceptor outer segments increased by lysosomal alkalinization was restored 73% by a P2X7R antagonist. Together, this suggests that endogenous autostimulation of the P2X7R may oxidize lipids and impede clearance. The P2X7R was expressed on apical and basolateral membranes of mouse RPE; mRNA expression of P2X7R and extracellular ATP marker NTPDase1 was raised in RPE tissue from the ABCA4(-/-) mouse model of Stargardt's retinal degeneration. In summary, P2X7R stimulation raises lysosomal pH and impedes lysosomal function, suggesting a possible role for overstimulation in diseases of accumulation.
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Affiliation(s)
- Sonia Guha
- 1Department of Anatomy and Cell Biology, University of Pennsylvania, 440 Levy Bldg., 240 S. 40th St., Philadelphia, PA 19104, USA.
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Effect of Day Length on Eye Growth, Myopia Progression, and Change of Corneal Power in Myopic Children. Ophthalmology 2013; 120:1074-9. [DOI: 10.1016/j.ophtha.2012.10.022] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Revised: 10/08/2012] [Accepted: 10/17/2012] [Indexed: 11/20/2022] Open
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Guzman-Aranguez A, Santano C, Martin-Gil A, Fonseca B, Pintor J. Nucleotides in the eye: focus on functional aspects and therapeutic perspectives. J Pharmacol Exp Ther 2013; 345:331-41. [PMID: 23504005 DOI: 10.1124/jpet.112.202473] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The presence and activity of nucleotides and dinucleotides in the physiology of most, if not all, organisms, from bacteria to humans, have been recognized by the scientific community, and the eye is no exception. Nucleotides in the dynamic fluids interact with many ocular structures, such as the tears and aqueous humor. Moreover, high concentrations of nucleotides in these secretions may reflect disease states such as dry eye and glaucoma. Apart from the nucleotide concentration in these fluids, P2 purinergic receptors have been described on the ocular surface (cornea and conjunctiva), anterior pole (ciliary body, trabecular meshwork), and posterior pole (retina). P2X and P2Y purinergic receptors are essential in maintaining the homeostasis of ocular processes, such as tear secretion, aqueous humor production, or retinal modulation. When they are functioning properly, they allow the eye to do its job (to see), but in some cases, a lack or an excess of nucleotides or a malfunction in the corresponding purinergic receptors leads to disease. This Perspective is focused on the nucleotides and dinucleotides and the P2 purinergic receptors in the eye and how they contribute to normal and disease states. We also emphasize the action of nucleotides and their receptors and antagonists as potential therapeutic agents.
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Affiliation(s)
- Ana Guzman-Aranguez
- Department of Biochemistry and Molecular Biology, Faculty of Optics and Optometry, Universidad Complutense Madrid, C/Arcos de Jalón 118, 28037 Madrid, Spain
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Abstract
The common theme of this introductory article and the minireviews that follow in this special issue is the concept of microenvironments within tissues and surrounding cells that would be ideal signaling venues for a biologically active purinergic ligand. Collectively, the editors/authors and the other contributing authors agree that nucleotides and nucleosides would be most potent within a confined system. A talented cadre of purinergics has been solicited to discuss purinergic signaling in his or her favorite microenvironment within a given organ or tissue. We are gratified by the large number of original articles that also have successfully navigated the peer review process and are part of this special issue. These concepts are not simply purinergic, but the idea of maximal potency in a tissue microenvironment and surrounding specialized cells within a tissue pertains to any autacoid or paracrine agonist.
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Affiliation(s)
- Erik M Schwiebert
- Departments of Physiology and Biophysics and Cell Biology, University of Alabama at Birmingham, Birmingham, AL, USA.
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The presence of bestrophin-1 modulates the Ca2+ recruitment from Ca2+ stores in the ER. Pflugers Arch 2010; 460:163-75. [PMID: 20411394 DOI: 10.1007/s00424-010-0840-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2009] [Revised: 03/23/2010] [Accepted: 04/03/2010] [Indexed: 10/19/2022]
Abstract
Bestrophin-1, mainly analyzed in overexpression experiments, functions as Ca(2+)-dependent Cl(-) channel. Analysis of endogenously expressed bestrophin-1 suggested an influence on intracellular Ca(2+). The aim of the study is to analyze the influence of endogenously expressed bestrophin-1 on Ca(2+) homeostasis. Primary cultures of retinal pigment epithelial (RPE) cells were established from wild-type and bestrophin-1-deficient mice. Intracellular free Ca(2+) ([Ca(2+)](i)) was recorded by Ca(2+) imaging; through immunocytochemistry and differential centrifugation, subcellular localization of bestrophin-1 was analyzed. RPE cells of bestrophin-1-deficient mice showed higher levels of resting [Ca(2+)](i) than cells from wild-type mice. In cells from knockout mice and wild-type mice, ATP led to increases in [Ca(2+)](i) subsequent to phospholipase C activation. ATP-induced Ca(2+) in bestrophin-1-deficient mice rose faster and decayed slower. In cells from wild-type mice, ATP led to [Ca(2+)](i) increase via depletion of Ca(2+) from thapsigargin-sensitive stores. In cells from bestrophin-1-deficient mice, ATP-dependent increase in [Ca(2+)](i) resulted in 40% of cells from depletion of bafilomycin-sensitive and in 60% from thapsigargin-sensitive Ca(2+) stores. After differential centrifugation, bestrophin-1 was found in fractions enriched of ClC-3 Cl channel and myosin-7A. Co-localization analysis of bestrophin-1, with beta-catenin or pan-cadherin, in fresh sections of porcine retina, revealed bestrophin-1 in the basolateral membrane. A portion of endogenously expressed bestrophin-1,localized in the endoplasmic reticulum, influenced uptake of Ca(2+) into Ca(2+) stores. Therefore, bestrophin-1 possibly conducts Cl(-) as counter ion for Ca(2+) uptake into cytosolic Ca(2+) stores.
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Kaarniranta K, Salminen A. Age-related macular degeneration: activation of innate immunity system via pattern recognition receptors. J Mol Med (Berl) 2008; 87:117-23. [PMID: 19009282 DOI: 10.1007/s00109-008-0418-z] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2008] [Accepted: 10/29/2008] [Indexed: 12/25/2022]
Abstract
Age-related macular degeneration (AMD) is the most common cause of irreversible loss of central vision. Histopathological studies have demonstrated that inflammation is the key player in the pathogenesis of AMD. Genetic studies have revealed that complement factor H is a strong risk factor for the development of AMD. However, innate immunity defence involves several other pattern recognition receptors (PRRs) which can trigger inflammatory responses. Retinal pigment epithelial (RPE) cells have the main role in the immune defence in macula. In this study, we examine in detail the endogenous danger signals which can activate different PRRs in RPE cells, such as Toll-like, NOD-like and scavenger receptors along with complement system. We also characterise the signalling pathways triggered by PRRs in evoking inflammatory responses. In addition, we will discuss whether AMD pathology could represent the outcome of chronic activation of the innate immunity defence in human macula.
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Affiliation(s)
- K Kaarniranta
- Department of Ophthalmology, Institute of Clinical Medicine, University of Kuopio, P.O. Box 1627, 70211, Kuopio, Finland.
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Reigada D, Lu W, Zhang M, Mitchell CH. Elevated pressure triggers a physiological release of ATP from the retina: Possible role for pannexin hemichannels. Neuroscience 2008; 157:396-404. [PMID: 18822352 DOI: 10.1016/j.neuroscience.2008.08.036] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2008] [Revised: 07/26/2008] [Accepted: 08/19/2008] [Indexed: 01/16/2023]
Abstract
Increased hydrostatic pressure can damage neurons, although the mechanisms linking pressure to neurochemical imbalance or cell injury are not fully established. Throughout the body, mechanical perturbations such as shear stress, cell stretching, or changes in pressure can lead to excessive release of ATP. It is thus possible that increased pressure across neural tissues triggers an elevated release of ATP into extracellular space. As stimulation of the P2X(7) receptor for ATP on retinal ganglion cells leads to elevation of intracellular calcium and excitotoxic death, we asked whether increased levels of extracellular ATP accompanied an elevation in pressure across the retina. The hydrostatic pressure surrounding bovine retinal eyecups was increased and the ATP content of the vitreal compartment adjacent to the retina was determined. A step increase of only 20 mm Hg induced a threefold increase in the vitreal ATP concentration. The ATP levels correlated closely with the degree of pressure increase over 20-100 mm Hg. The increase was transient at lower pressures but sustained at higher pressures. The rise in vitreal ATP was the same regardless of whether nitrogen or air was used to increase pressure, implying changes in oxygen partial pressure did not contribute. Lactate dehydrogenase activity was not affected by pressure, ruling out a substantial contribution from cell lysis. The ATP increase was largely inhibited by either 30 muM 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) or 10 muM carbenoxolone (CBX). While this pharmacological profile is consistent with physiological release of ATP through pannexins hemichannels, a contribution from anion channels, vesicular release or other mechanisms cannot be ruled out. In conclusion, a step elevation in pressure leads to a physiologic increase in the levels of extracellular ATP bathing retinal neurons. This excess extracellular ATP may link increased pressure to the death of ganglion cells in acute glaucoma, and suggests a possible role for ATP in the neuronal damage accompanying increased intracranial pressure.
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Affiliation(s)
- D Reigada
- Department of Physiology, University of Pennsylvania, 3700 Hamilton Walk, Philadelphia, PA 19104-6085, USA
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Liu J, Lu W, Reigada D, Nguyen J, Laties AM, Mitchell CH. Restoration of lysosomal pH in RPE cells from cultured human and ABCA4(-/-) mice: pharmacologic approaches and functional recovery. Invest Ophthalmol Vis Sci 2008; 49:772-80. [PMID: 18235027 DOI: 10.1167/iovs.07-0675] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
PURPOSE Degradation of engulfed material is primarily mediated by lysosomal enzymes that function optimally within a narrow range of acidic pH values. RPE cells are responsible for daily degradation of photoreceptor outer segments and are thus particularly susceptible to perturbations in lysosomal pH. The authors hypothesized that elevated lysosomal pH levels could slow enzyme activity and encourage accumulation of partially digested material. Consequently, treatment to lower perturbed lysosomal pH levels may enhance degradative activity. METHODS A high-throughput screening assay was developed to quantify the lysosomal pH of fresh mouse and cultured ARPE-19 cells. The effect of lysosomal pH on outer segment clearance was determined. RESULTS Lysosomal pH is elevated in RPE cells from ABCA4 knockout mice and in cultured human ARPE-19 cells exposed to N-retinylidene-N-retinylethanolamine (A2E), tamoxifen, or chloroquine. The lysosomal pH of fresh RPE cells from ABCA4(-/-) mice and of chemically compromised RPE cells was reacidified by elevating intracellular cAMP directly. Compromised lysosomal pH was also restored by stimulating A(2A) adenosine or beta-adrenergic receptors, consistent with G(s)-protein coupling of these receptors. Restoring lysosomal pH with these treatments enhanced photoreceptor outer segment clearance, demonstrating functional relevance consistent with an enhancement of degradative enzyme activity. CONCLUSIONS Elevation of lysosomal pH in RPE cells interferes with the degradation of outer segments and may contribute to the pathologies associated with A2E. Pharmacologic elevation of cAMP can restore an acid pH and improve degradative function.
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Affiliation(s)
- Ji Liu
- Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104-6085, USA
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Lu W, Reigada D, Sévigny J, Mitchell CH. Stimulation of the P2Y1 receptor up-regulates nucleoside-triphosphate diphosphohydrolase-1 in human retinal pigment epithelial cells. J Pharmacol Exp Ther 2007; 323:157-64. [PMID: 17626796 PMCID: PMC5239667 DOI: 10.1124/jpet.107.124545] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Stimulation of receptors for either ATP or adenosine leads to physiologic changes in retinal pigment epithelial (RPE) cells that may influence their relationship with the adjacent photoreceptors. The ectoenzyme nucleoside-triphosphate diphosphohydrolase-1 (NTPDase1) catalyzes the dual dephosphorylation of ATP and ADP to AMP. Although NTPDase1 can consequently control the balance between ATP and adenosine, it is unclear how its expression and activity are regulated. Classic negative feedback theory predicts an increase in enzyme activity in response to enhanced exposure to substrate. This study asked whether exposure to ATP increases NTPDase1 activity in RPE cells. Although levels of NTPDase1 mRNA and protein in cultured human ARPE-19 cells were generally low under control conditions, exposure to slowly hydrolyzable ATPgammaS led to a time-dependent increase in NTPDase1 mRNA that was accompanied by a rise in levels of the functional 78-kDa protein. Neither NTPDase2 nor NTPDase3 mRNA message was elevated by ATPgammaS. The ATPase activity of cells increased in parallel, indicating the up-regulation of NTPDase1 was functionally relevant. The up-regulation of NTPDase1 protein was partially blocked by P2Y1 receptor inhibitors MRS2179 (N6-methyl-2'-deoxyadenosine-3',5'-bisphosphate) and MRS2500 [2-iodo-N6-methyl-(N)-methanocarba-2'-deoxyadenosine 3',5'-bisphosphate] and increased by P2Y1 receptor agonist MRS2365 [(N)-methanocarba-2MeSADP]. In conclusion, prolonged exposure to extracellular ATPgammaS increased NTPDase1 message and protein levels and increased ecto-ATPase activity. This up-regulation reflects a feedback circuit, mediated at least in part by the P2Y1 receptor, to regulate levels of extracellular purines in subretinal space. NTPDase1 levels may thus serve as an index for increased extracellular ATP levels under certain pathologic conditions, although other mechanisms could also contribute.
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Affiliation(s)
- Wennan Lu
- Department of Physiology, University of Pennsylvania, 3700 Hamilton Walk, Philadelphia, PA 19104-6085, USA
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