1
|
Różanowska MB. Lipofuscin, Its Origin, Properties, and Contribution to Retinal Fluorescence as a Potential Biomarker of Oxidative Damage to the Retina. Antioxidants (Basel) 2023; 12:2111. [PMID: 38136230 PMCID: PMC10740933 DOI: 10.3390/antiox12122111] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 12/05/2023] [Accepted: 12/09/2023] [Indexed: 12/24/2023] Open
Abstract
Lipofuscin accumulates with age as intracellular fluorescent granules originating from incomplete lysosomal digestion of phagocytosed and autophagocytosed material. The purpose of this review is to provide an update on the current understanding of the role of oxidative stress and/or lysosomal dysfunction in lipofuscin accumulation and its consequences, particularly for retinal pigment epithelium (RPE). Next, the fluorescence of lipofuscin, spectral changes induced by oxidation, and its contribution to retinal fluorescence are discussed. This is followed by reviewing recent developments in fluorescence imaging of the retina and the current evidence on the prognostic value of retinal fluorescence for the progression of age-related macular degeneration (AMD), the major blinding disease affecting elderly people in developed countries. The evidence of lipofuscin oxidation in vivo and the evidence of increased oxidative damage in AMD retina ex vivo lead to the conclusion that imaging of spectral characteristics of lipofuscin fluorescence may serve as a useful biomarker of oxidative damage, which can be helpful in assessing the efficacy of potential antioxidant therapies in retinal degenerations associated with accumulation of lipofuscin and increased oxidative stress. Finally, amendments to currently used fluorescence imaging instruments are suggested to be more sensitive and specific for imaging spectral characteristics of lipofuscin fluorescence.
Collapse
Affiliation(s)
- Małgorzata B. Różanowska
- School of Optometry and Vision Sciences, College of Biomedical and Life Sciences, Cardiff University, Maindy Road, Cardiff CF24 4HQ, Wales, UK;
- Cardiff Institute for Tissue Engineering and Repair (CITER), Redwood Building, King Edward VII Avenue, Cardiff CF10 3NB, Wales, UK
| |
Collapse
|
2
|
Kotnala A, Senthilkumari S, Wu G, Stewart TG, Curcio CA, Halder N, Singh SB, Kumar A, Velpandian T. Retinal Pigment Epithelium in Human Donor Eyes Contains Higher Levels of Bisretinoids Including A2E in Periphery than Macula. Invest Ophthalmol Vis Sci 2022; 63:6. [PMID: 35671050 PMCID: PMC9187938 DOI: 10.1167/iovs.63.6.6] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose With age, human retinal pigment epithelium (RPE) accumulates bisretinoid fluorophores that may impact cellular function and contribute to age-related macular degeneration (AMD). Bisretinoids are comprised of a central pyridinium, dihydropyridinium, or cyclohexadiene ring. The pyridinium bisretinoid A2E has been extensively studied, and its quantity in the macula has been questioned. Age-changes and distributions of other bisretinoids are not well characterized. We measured levels of three bisretinoids and oxidized A2E in macula and periphery in human donor eyes of different ages. Methods Eyes (N = 139 donors, 61 women and 78 men, aged 40–80 years) were dissected into 8 mm diameter macular and temporal periphery punches. Using liquid chromatography – electrospray ionization – mass spectrometry (LC-ESI-MS) and an authentic synthesized standard, we quantified A2E (ng). Using LC-ESI-MS and a 50-eye-extract of A2E, we semiquantified A2E and 3 other compounds (eye extract equivalent units [EEEUs): A2-glycerophosphoethanolamine (A2GPE), dihydropyridine phosphatidyl ethanolamine (A2DHPE), and monofuranA2E (MFA2E). Results A2E quantities in ng and EEEUs were highly correlated (r = 0.97, P < 0.001). From 262 eyes, 5 to 9-fold higher levels were observed in the peripheral retina than in the macula for all assayed compounds. A2E, A2DHPE, and MFA2E increased with age, whereas A2GPE remained unaffected. No significant right-left or male-female differences were detected. Conclusions Significantly higher levels were observed in the periphery than in the macula for all assayed compounds signifying biologic differences between these regions. Levels of oxidized A2E parallel native A2E and not the distribution of retinal illuminance. Data will assist with the interpretion of clinical trial outcomes of agents targeting bisretinoid-related pathways.
Collapse
Affiliation(s)
- Ankita Kotnala
- Ocular Pharmacology & Pharmacy Division, All India Institute of Medical Sciences, New Delhi, India
| | - Srinivasan Senthilkumari
- Department of Ocular Pharmacology, Aravind Medical Research Foundation (AMRF), Dr. G. Venkataswamy Eye Research Institute, #1, Anna Nagar, Madurai -20, Tamilnadu, India
| | - Gong Wu
- Department of Biostatics, Vanderbilt University Medical Centre, Nashville, Tennessee, United States
| | - Thomas G Stewart
- Department of Biostatics, Vanderbilt University Medical Centre, Nashville, Tennessee, United States
| | - Christine A Curcio
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Nabanita Halder
- Ocular Pharmacology & Pharmacy Division, All India Institute of Medical Sciences, New Delhi, India
| | | | - Atul Kumar
- Department of Ophthalmology, Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Thirumurthy Velpandian
- Ocular Pharmacology & Pharmacy Division, All India Institute of Medical Sciences, New Delhi, India
| |
Collapse
|
3
|
Różanowska MB, Różanowski B. Photodegradation of Lipofuscin in Suspension and in ARPE-19 Cells and the Similarity of Fluorescence of the Photodegradation Product with Oxidized Docosahexaenoate. Int J Mol Sci 2022; 23:ijms23020922. [PMID: 35055111 PMCID: PMC8778276 DOI: 10.3390/ijms23020922] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Revised: 01/07/2022] [Accepted: 01/12/2022] [Indexed: 02/01/2023] Open
Abstract
Retinal lipofuscin accumulates with age in the retinal pigment epithelium (RPE), where its fluorescence properties are used to assess retinal health. It was observed that there is a decrease in lipofuscin fluorescence above the age of 75 years and in the early stages of age-related macular degeneration (AMD). The purpose of this study was to investigate the response of lipofuscin isolated from human RPE and lipofuscin-laden cells to visible light, and to determine whether an abundant component of lipofuscin, docosahexaenoate (DHA), can contribute to lipofuscin fluorescence upon oxidation. Exposure of lipofuscin to visible light leads to a decrease in its long-wavelength fluorescence at about 610 nm, with a concomitant increase in the short-wavelength fluorescence. The emission spectrum of photodegraded lipofuscin exhibits similarity with that of oxidized DHA. Exposure of lipofuscin-laden cells to light leads to a loss of lipofuscin granules from cells, while retaining cell viability. The spectral changes in fluorescence in lipofuscin-laden cells resemble those seen during photodegradation of isolated lipofuscin. Our results demonstrate that fluorescence emission spectra, together with quantitation of the intensity of long-wavelength fluorescence, can serve as a marker useful for lipofuscin quantification and for monitoring its oxidation, and hence useful for screening the retina for increased oxidative damage and early AMD-related changes.
Collapse
Affiliation(s)
- Małgorzata B. Różanowska
- School of Optometry and Vision Sciences, Cardiff University, Cardiff CF24 4HQ, UK
- Cardiff Institute for Tissue Engineering and Repair (CITER), Cardiff University, Cardiff CF10 3NB, UK
- Correspondence: ; Tel.: +44-2920875057
| | - Bartosz Różanowski
- Institute of Biology, Pedagogical University of Kraków, 30-084 Kraków, Poland;
| |
Collapse
|
4
|
Bermond K, von der Emde L, Tarau IS, Bourauel L, Heintzmann R, Holz FG, Curcio CA, Sloan KR, Ach T. Autofluorescent Organelles Within the Retinal Pigment Epithelium in Human Donor Eyes With and Without Age-Related Macular Degeneration. Invest Ophthalmol Vis Sci 2022; 63:23. [PMID: 35050307 PMCID: PMC8787573 DOI: 10.1167/iovs.63.1.23] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Purpose Human retinal pigment epithelium (RPE) cells contain lipofuscin, melanolipofuscin, and melanosome organelles that impact clinical autofluorescence (AF) imaging. Here, we quantified the effect of age-related macular degeneration (AMD) on granule count and histologic AF of RPE cell bodies. Methods Seven AMD-affected human RPE-Bruch's membrane flatmounts (early and intermediate = 3, late dry = 1, and neovascular = 3) were imaged at fovea, perifovea, and near periphery using structured illumination and confocal AF microscopy (excitation 488 nm) and compared to RPE-flatmounts with unremarkable macula (n = 7, >80 years). Subsequently, granules were marked with computer assistance, and classified by their AF properties. The AF/cell was calculated from confocal images. The total number of granules and AF/cell was analyzed implementing a mixed effect analysis of covariance (ANCOVA). Results A total of 152 AMD-affected RPE cells were analyzed (fovea = 22, perifovea = 60, and near-periphery = 70). AMD-affected RPE cells showed increased variability in size and a significantly increased granule load independent of the retinal location (fovea: P = 0.02, perifovea: P = 0.04, and near periphery: P < 0.01). The lipofuscin fraction of total organelles decreased and the melanolipofuscin fraction increased in AMD, at all locations (especially the fovea). AF was significantly lower in AMD-affected cells (fovea: <0.01, perifovea: <0.01, and near periphery: 0.02). Conclusions In AMD RPE, lipofuscin was proportionately lowest in the fovea, a location also known to be affected by accumulation of soft drusen and preservation of cone-mediated visual acuity. Enlarged RPE cell bodies displayed increased net granule count but diminished total AF. Future studies should also assess the impact on AF imaging of RPE apical processes containing melanosomes.
Collapse
Affiliation(s)
- Katharina Bermond
- Department of Ophthalmology, Ludwigshafen Hospital, Ludwigshafen, Germany
| | - Leon von der Emde
- Department of Ophthalmology, University Hospital Bonn, Bonn, Germany
| | - Ioana-Sandra Tarau
- Department of Ophthalmology, University Hospital Würzburg, Würzburg, Germany
| | - Leonie Bourauel
- Department of Ophthalmology, University Hospital Bonn, Bonn, Germany
| | - Rainer Heintzmann
- Leibniz Institute of Photonic Technology, Jena, Germany.,Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich-Schiller University Jena, Jena, Germany
| | - Frank G Holz
- Department of Ophthalmology, University Hospital Bonn, Bonn, Germany
| | - Christine A Curcio
- Department of Ophthalmology, University of Alabama at Birmingham, Alabama, AL, United States
| | - Kenneth R Sloan
- Department of Ophthalmology, University of Alabama at Birmingham, Alabama, AL, United States
| | - Thomas Ach
- Department of Ophthalmology, University Hospital Bonn, Bonn, Germany
| |
Collapse
|
5
|
Abstract
Cholesterol is a quantitatively and biologically significant constituent of all mammalian cell membrane, including those that comprise the retina. Retinal cholesterol homeostasis entails the interplay between de novo synthesis, uptake, intraretinal sterol transport, metabolism, and efflux. Defects in these complex processes are associated with several congenital and age-related disorders of the visual system. Herein, we provide an overview of the following topics: (a) cholesterol synthesis in the neural retina; (b) lipoprotein uptake and intraretinal sterol transport in the neural retina and the retinal pigment epithelium (RPE); (c) cholesterol efflux from the neural retina and the RPE; and (d) biology and pathobiology of defects in sterol synthesis and sterol oxidation in the neural retina and the RPE. We focus, in particular, on studies involving animal models of monogenic disorders pertinent to the above topics, as well as in vitro models using biochemical, metabolic, and omic approaches. We also identify current knowledge gaps and opportunities in the field that beg further research in this topic area.
Collapse
Affiliation(s)
- Sriganesh Ramachandra Rao
- Departments of Ophthalmology and Biochemistry and Neuroscience Graduate Program, Jacobs School of Medicine and Biomedical Sciences, State University of New York- University at Buffalo, Buffalo, NY, USA; Research Service, VA Western NY Healthcare System, Buffalo, NY, USA
| | - Steven J Fliesler
- Departments of Ophthalmology and Biochemistry and Neuroscience Graduate Program, Jacobs School of Medicine and Biomedical Sciences, State University of New York- University at Buffalo, Buffalo, NY, USA; Research Service, VA Western NY Healthcare System, Buffalo, NY, USA.
| |
Collapse
|
6
|
Comment and response to the article "The clinical relevance of visualizing the peripheral retina"by Nicola Quinn, Lajos Csincsik, Erin Flynn, Christine A. Curcio, Szilard Kiss, SriniVas R. Sadda, Ruth Hogg, Tunde Peto & Imre Lengyel. Prog Retin Eye Res 2021; 83:100939. [PMID: 33453363 DOI: 10.1016/j.preteyeres.2020.100939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
7
|
Boughton BA, Thomas ORB, Demarais NJ, Trede D, Swearer SE, Grey AC. Detection of small molecule concentration gradients in ocular tissues and humours. JOURNAL OF MASS SPECTROMETRY : JMS 2020; 55:e4460. [PMID: 31654531 DOI: 10.1002/jms.4460] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 10/02/2019] [Accepted: 10/17/2019] [Indexed: 06/10/2023]
Abstract
The eye is an elegant organ consisting of a number of tissues and fluids with specialised functions that together allow it to effectively transmit and transduce light input to the brain for visual perception. One key determinant of this integrated function is the spatial relationship of ocular tissues. Biomolecular distributions within the main ocular tissues cornea, lens, and retina have been studied extensively in isolation, yet the potential for metabolic communication between ocular tissues via the ocular humours has been difficult to visualise. To address this limitation, the current study presents a method to map spatial distributions of metabolites and small molecules in whole eyes, including ocular humours. Using a tape-transfer system and freeze-drying, the spatial distribution of ocular small molecules was investigated in mouse, rat, fish (black bream), and rabbit eyes using negative ion mode MALDI imaging mass spectrometry. Full-scan imaging was used for discovery experiments, while MS/MS imaging for identification and localisation was also demonstrated. In all eyes, metabolites such as glutathione and phospholipids were localised in the main ocular tissues. In addition, in rodent eyes, major metabolites were distributed relatively uniformly in ocular humours. In contrast, both uniform and spatially defined ocular metabolite distributions were observed in the black bream eye. Tissue and ocular humour distributions were reproducible, as demonstrated by the three-dimensional analysis of a mouse eye, and able to be captured with high spatial resolution analysis. The presented method could be used to further investigate the role of inter-tissue metabolism in ocular health, and to support the development of therapeutics to treat major ocular diseases.
Collapse
Affiliation(s)
- Berin A Boughton
- Metabolomics Australia, University of Melbourne, Melbourne, Australia
| | - Oliver R B Thomas
- School of BioSciences, University of Melbourne, Melbourne, Australia
| | - Nicholas J Demarais
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | | | - Stephen E Swearer
- School of BioSciences, University of Melbourne, Melbourne, Australia
| | - Angus C Grey
- School of Medical Sciences, University of Auckland, Auckland, New Zealand
| |
Collapse
|
8
|
Leclaire MD, Nettels-Hackert G, König J, Höhn A, Grune T, Uhlig CE, Hansen U, Eter N, Heiduschka P. Lipofuscin-dependent stimulation of microglial cells. Graefes Arch Clin Exp Ophthalmol 2019; 257:931-952. [PMID: 30693383 DOI: 10.1007/s00417-019-04253-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 01/10/2019] [Accepted: 01/17/2019] [Indexed: 01/10/2023] Open
Abstract
PURPOSE To examine the reaction of microglial cells (MG) when incubated with lipofuscin (LP) in vitro with emphasis on the immunological reaction of the MG toward LP and the suppression of this reaction by immunomodulatory agents. MG are involved in the pathogenesis of degenerative eye disorders such as age-related macular degeneration (AMD). LP is a heterogeneous waste material that accumulates in the retinal pigment epithelium (RPE) cells with advancing age. LP is known to have toxic effects on RPE cells and therefore an elevated LP-derived fundus autofluorescence is a risk factor for AMD development. MG in the subretinal space have been reported in eyes affected by AMD. Moreover, in senescent mice, subretinal MG were found, which display an autofluorescence that may be derived from LP uptake. METHODS In this study, we incubated MG (BV-2 cell line and primary cells from murine brain) in vitro with LP isolated from the human RPE. We observed phagocytosis, studied cell morphologies, and analyzed the cell culture supernatants. We also investigated the effect of the immunomodulatory agents hydrocortisone (HC), minocycline, and the tripeptide TKP. RESULTS The MG phagocytosed the LP quickly and completely. We detected highly elevated levels of pro-inflammatory cytokines (especially of IL-6, IL-23p19, TNF-α, KC, RANTES, and IL-1α) in the cell culture supernatants. Furthermore, levels of vascular endothelial growth factor (VEGF) were raised in BV-2 cells. Anti-inflammatory agents added to the cell cultures inhibited the inflammatory reaction, in particular hydrocortisone (HC). Minocycline and TKP had less impact on the cytokine release. CONCLUSION The interaction of MG and LP could play a role in the development of retinal degeneration by triggering an inflammatory reaction and angiogenesis.
Collapse
Affiliation(s)
- Martin Dominik Leclaire
- Research Laboratory, Department of Ophthalmology, University Medical Center, Domagkstr. 15, D-48149, Münster, Germany
| | - Gerburg Nettels-Hackert
- Research Laboratory, Department of Ophthalmology, University Medical Center, Domagkstr. 15, D-48149, Münster, Germany
| | - Jeannette König
- German Institute of Human Nutrition, Potsdam-Rehbrücke, Germany
| | - Annika Höhn
- German Institute of Human Nutrition, Potsdam-Rehbrücke, Germany
| | - Tilman Grune
- German Institute of Human Nutrition, Potsdam-Rehbrücke, Germany
| | - Constantin E Uhlig
- Cornea Bank Münster, Department of Ophthalmology, University Medical Center, Münster, Germany
| | - Uwe Hansen
- Institute of Experimental Musculoskeletal Medicine, Medical Faculty, University of Münster, Münster, Germany
| | - Nicole Eter
- Research Laboratory, Department of Ophthalmology, University Medical Center, Domagkstr. 15, D-48149, Münster, Germany
| | - Peter Heiduschka
- Research Laboratory, Department of Ophthalmology, University Medical Center, Domagkstr. 15, D-48149, Münster, Germany.
| |
Collapse
|
9
|
Curcio CA. Antecedents of Soft Drusen, the Specific Deposits of Age-Related Macular Degeneration, in the Biology of Human Macula. Invest Ophthalmol Vis Sci 2018; 59:AMD182-AMD194. [PMID: 30357337 PMCID: PMC6733529 DOI: 10.1167/iovs.18-24883] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
AMD pathobiology was irreversibly changed by the recent discovery of extracellular cholesterol-containing deposits in the subretinal space, between the photoreceptors and retinal pigment epithelium (RPE), called subretinal drusenoid deposits (SDDs). SDDs strikingly mirror the topography of rod photoreceptors in human macula, raising the question of whether an equivalent process results in a deposition related to foveal cones. Herein we propose that AMD's pathognomonic lesion-soft drusen and basal linear deposit (BLinD, same material, diffusely distributed)-is the leading candidate. Epidemiologic, clinical, and histologic data suggest that these deposits are most abundant in the central macula, under the fovea. Strong evidence presented in a companion article supports the idea that the dominant ultrastructural component is large apolipoprotein B,E-containing lipoproteins, constitutively secreted by RPE. Lipoprotein fatty acids are dominated by linoleate (implicating diet) rather than docosahexaenoate (implicating photoreceptors); we seek within the retina cellular relationships and dietary drivers to explain soft druse topography. The delivery of xanthophyll pigments to highly evolved and numerous Müller cells in the human fovea, through RPE, is one strong candidate, because Müller cells are the main reservoir of these pigments, which replenish from diet. We propose that the evolution of neuroglial relations and xanthophyll delivery that underlie exquisite human foveal vision came with a price, that is, soft drusen and sequela, long after our reproductive years.
Collapse
Affiliation(s)
- Christine A Curcio
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
| |
Collapse
|
10
|
SPECKLED HYPOAUTOFLUORESCENCE AS A SIGN OF RESOLVED SUBRETINAL HEMORRHAGE IN NEOVASCULAR AGE-RELATED MACULAR DEGENERATION. Retina 2018; 39:1925-1935. [PMID: 30355956 DOI: 10.1097/iae.0000000000002367] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
PURPOSE To describe patterns of hypoautofluorescence in eyes with neovascular age-related macular degeneration occurring after subretinal hemorrhage. METHODS This was a retrospective descriptive analysis of neovascular age-related macular degeneration eyes presenting with subretinal hemorrhage over the last 5 years that underwent serial multimodal imaging. A review of color fundus photographs, fundus autofluorescence, near-infrared reflectance, and optical coherence tomography was performed at baseline and all available follow-up visits to document the course and evolution of subretinal hemorrhage in these eyes. RESULTS Eleven eyes of 10 patients (9 female, 1 male; mean age: 84.1 years, range: 72-99 years) with a mean follow-up of 19.8 months (range: 3-68 months) were included. Color fundus photographs showed subretinal hemorrhage that resolved over a mean of 5.5 months. During and after hemorrhage resolution, all eyes showed hypoautofluorescence, which appeared distinct from that due to retinal pigment epithelium loss. Discrete multifocal punctate hyperpigmented lesions were observed in 90% of eyes and were markedly hypoautofluorescent, producing a speckled pattern on fundus autofluorescence. CONCLUSION Areas of hypoautofluorescence in the absence of retinal pigment epithelium atrophy, often with a speckled pattern, delineate areas of prior subretinal hemorrhage long after its resolution in patients with neovascular age-related macular degeneration. Potential mechanisms for the development of this pattern are proposed.
Collapse
|
11
|
Hussain RM, Gregori NZ, Ciulla TA, Lam BL. Pharmacotherapy of retinal disease with visual cycle modulators. Expert Opin Pharmacother 2018. [DOI: 10.1080/14656566.2018.1448060] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Rehan M. Hussain
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Ninel Z. Gregori
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Thomas A. Ciulla
- Department of Ophthalmology, Retina Service, Midwest Eye Institute, Indianapolis, IN, USA
- Retina Service, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Byron L. Lam
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA
| |
Collapse
|
12
|
Anderson DMG, Ablonczy Z, Koutalos Y, Hanneken AM, Spraggins JM, Calcutt MW, Crouch RK, Caprioli RM, Schey KL. Bis(monoacylglycero)phosphate lipids in the retinal pigment epithelium implicate lysosomal/endosomal dysfunction in a model of Stargardt disease and human retinas. Sci Rep 2017; 7:17352. [PMID: 29229934 PMCID: PMC5725462 DOI: 10.1038/s41598-017-17402-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 11/22/2017] [Indexed: 01/10/2023] Open
Abstract
Stargardt disease is a juvenile onset retinal degeneration, associated with elevated levels of lipofuscin and its bis-retinoid components, such as N-retinylidene-N-retinylethanolamine (A2E). However, the pathogenesis of Stargardt is still poorly understood and targeted treatments are not available. Utilizing high spatial and high mass resolution matrix assisted laser desorption ionization (MALDI) imaging mass spectrometry (IMS), we determined alterations of lipid profiles specifically localized to the retinal pigment epithelium (RPE) in Abca4 -/- Stargardt model mice compared to their relevant background strain. Extensive analysis by LC-MS/MS in both positive and negative ion mode was required to accurately confirm the identity of one highly expressed lipid class, bis(monoacylgylercoro)phosphate (BMP) lipids, and to distinguish them from isobaric species. The same BMP lipids were also detected in the RPE of healthy human retina. BMP lipids have been previously associated with the endosomal/lysosomal storage diseases Niemann-Pick and neuronal ceroid lipofuscinosis and have been reported to regulate cholesterol levels in endosomes. These results suggest that perturbations in lipid metabolism associated with late endosomal/lysosomal dysfunction may play a role in the pathogenesis of Stargardt disease and is evidenced in human retinas.
Collapse
Affiliation(s)
- David M G Anderson
- Mass Spectrometry Research Center and Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Zsolt Ablonczy
- Department of Ophthalmology, Storm Eye Institute, Medical University of South Carolina, Charleston, SC, USA
- Preclinical Department, Ora Inc, Andover, MA, USA
| | - Yiannis Koutalos
- Department of Ophthalmology, Storm Eye Institute, Medical University of South Carolina, Charleston, SC, USA
| | - Anne M Hanneken
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Jeffrey M Spraggins
- Mass Spectrometry Research Center and Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
- Department of Biochemistry, Vanderbilt University, Nashville, TN, USA
- Department of Chemistry, Nashville, TN, USA
| | - M Wade Calcutt
- Mass Spectrometry Research Center and Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Rosalie K Crouch
- Department of Ophthalmology, Storm Eye Institute, Medical University of South Carolina, Charleston, SC, USA
| | - Richard M Caprioli
- Mass Spectrometry Research Center and Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
- Department of Biochemistry, Vanderbilt University, Nashville, TN, USA
- Department of Chemistry, Nashville, TN, USA
- Department of Pharmacology and Medicine, Vanderbilt University, Nashville, TN, USA
| | - Kevin L Schey
- Mass Spectrometry Research Center and Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA.
- Department of Biochemistry, Vanderbilt University, Nashville, TN, USA.
| |
Collapse
|
13
|
Pallitto P, Ablonczy Z, Jones EE, Drake RR, Koutalos Y, Crouch RK, Donello J, Herrmann J. A2E and lipofuscin distributions in macaque retinal pigment epithelium are similar to human. Photochem Photobiol Sci 2016. [PMID: 26223373 DOI: 10.1039/c5pp00170f] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The accumulation of lipofuscin, an autofluorescent aging marker, in the retinal pigment epithelium (RPE) has been implicated in the development of age-related macular degeneration (AMD). Lipofuscin contains several visual cycle byproducts, most notably the bisretinoid N-retinylidene-N-retinylethanolamine (A2E). Previous studies with human donor eyes have shown a significant mismatch between lipofuscin autofluorescence (AF) and A2E distributions. The goal of the current project was to examine this relationship in a primate model with a retinal anatomy similar to that of humans. Ophthalmologically naive young (<10 years., N = 3) and old (>10 years., N = 4) Macaca fascicularis (macaque) eyes, were enucleated, dissected to yield RPE/choroid tissue, and flat-mounted on indium-tin-oxide-coated conductive slides. To compare the spatial distributions of lipofuscin and A2E, fluorescence and mass spectrometric imaging were carried out sequentially on the same samples. The distribution of lipofuscin fluorescence in the primate RPE reflected previously obtained human results, having the highest intensities in a perifoveal ring. Contrarily, A2E levels were consistently highest in the periphery, confirming a lack of correlation between the distributions of lipofuscin and A2E previously described in human donor eyes. We conclude that the mismatch between lipofuscin AF and A2E distributions is related to anatomical features specific to primates, such as the macula, and that this primate model has the potential to fill an important gap in current AMD research.
Collapse
Affiliation(s)
- Patrick Pallitto
- Department of Ophthalmology, Storm Eye Institute, Medical University of South Carolina, USA.
| | | | | | | | | | | | | | | |
Collapse
|
14
|
Müller PL, Gliem M, Mangold E, Bolz HJ, Finger RP, McGuinness M, Betz C, Jiang Z, Weber BHF, MacLaren RE, Holz FG, Radu RA, Charbel Issa P. Monoallelic ABCA4 Mutations Appear Insufficient to Cause Retinopathy: A Quantitative Autofluorescence Study. Invest Ophthalmol Vis Sci 2016; 56:8179-86. [PMID: 26720470 DOI: 10.1167/iovs.15-17629] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To investigate the effect of ABCA4 mutation status on lipofuscin-related quantitative autofluorescence (qAF) in humans and on bisretinoid accumulation in mice. METHODS Genotyped parents (n = 26; age 37-64 years) of patients with biallelic ABCA4-related retinopathy underwent in-depth retinal phenotyping including qAF imaging as a surrogate measure for RPE lipofuscin accumulation. In addition, bisretinoids as the main components of autofluorescent lipofuscin at the ocular fundus were quantified in Abca4-/-, Abca4+/-, and wild-type mice. RESULTS Index patients showed a retinal phenotype characteristic for ABCA4-related retinopathy, including increased qAF levels. In contrast, qAF measures in carriers of only one ABCA4 mutation were not different from age-matched controls in this sample, and there was no difference between truncating and missense mutations. Also, none of these carriers presented an abnormal phenotype on conventional imaging. One parent with ABCA4-related retinopathy and increased qAF carried an additional ABCA4 mutation, explaining the phenotype under a recessive disease model (pseudodominance). Biochemical analysis in the mouse model revealed direct downstream products (A2PE-H2, at-RALdimer-PE) of the ABCA4 substrate N-Ret-PE to be similar in wild-type and Abca4+/- mice. Both bisretinoids were 12- to 18-fold increased in Abca4-/- mice. Levels of A2E and A2PE in Abca4+/- mice were in between those measured in wild-type and Abca4-/- mice. CONCLUSIONS This study indicates that carriers of monoallelic ABCA4 mutations are phenotypically normal. However, biochemical analysis in the Abca4-deficient mouse model suggests detectable effects of one mutation in ABCA4 on the molecular level. The findings may have implications for therapeutic approaches such as gene replacement therapy.
Collapse
Affiliation(s)
- Philipp L Müller
- Department of Ophthalmology, University of Bonn, Bonn, Germany 2Center for Rare Diseases Bonn (ZSEB), University Hospital of Bonn, Bonn, Germany
| | - Martin Gliem
- Department of Ophthalmology, University of Bonn, Bonn, Germany 2Center for Rare Diseases Bonn (ZSEB), University Hospital of Bonn, Bonn, Germany
| | | | - Hanno J Bolz
- Bioscientia Center for Human Genetics, Ingelheim, Germany 5Institute of Human Genetics, University Hospital of Cologne, Cologne, Germany
| | - Robert P Finger
- Department of Ophthalmology, University of Bonn, Bonn, Germany 6Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Australia
| | - Myra McGuinness
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Australia
| | - Christian Betz
- Bioscientia Center for Human Genetics, Ingelheim, Germany
| | - Zhichun Jiang
- Stein Eye Institute, Department of Ophthalmology, University of California-Los Angeles School of Medicine, Los Angeles, California, United States
| | - Bernhard H F Weber
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany
| | - Robert E MacLaren
- The Nuffield Laboratory of Ophthalmology & Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom
| | - Frank G Holz
- Department of Ophthalmology, University of Bonn, Bonn, Germany 2Center for Rare Diseases Bonn (ZSEB), University Hospital of Bonn, Bonn, Germany
| | - Roxana A Radu
- Stein Eye Institute, Department of Ophthalmology, University of California-Los Angeles School of Medicine, Los Angeles, California, United States
| | - Peter Charbel Issa
- Department of Ophthalmology, University of Bonn, Bonn, Germany 2Center for Rare Diseases Bonn (ZSEB), University Hospital of Bonn, Bonn, Germany
| |
Collapse
|
15
|
Bowrey HE, Anderson DM, Pallitto P, Gutierrez DB, Fan J, Crouch RK, Schey KL, Ablonczy Z. Imaging mass spectrometry of the visual system: Advancing the molecular understanding of retina degenerations. Proteomics Clin Appl 2016; 10:391-402. [PMID: 26586164 DOI: 10.1002/prca.201500103] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2015] [Revised: 08/15/2015] [Accepted: 11/11/2015] [Indexed: 11/08/2022]
Abstract
Visual sensation is fundamental for quality of life, and loss of vision to retinal degeneration is a debilitating condition. The eye is the only part of the central nervous system that can be noninvasively observed with optical imaging. In the clinics, various spectroscopic methods provide high spatial resolution images of the fundus and the developing degenerative lesions. However, the currently utilized tools are not specific enough to establish the molecular underpinnings of retinal diseases. In contrast, mass spectrometric imaging (MSI) is a powerful tool to identify molecularly specific disease indicators and classification markers. This technique is particularly well suited to the eye, where molecular information can be correlated with clinical data collected via noninvasive diagnostic imaging modalities. Recent studies during the last few recent years have uncovered a plethora of new spatially defined molecular information on several vision-threatening diseases, including age-related macular degeneration, Stargardt disease, glaucoma, cataract, as well as lipid disorders. Even though MS inside the eye cannot be performed noninvasively, by linking diagnostic and molecular information, these studies are the first step toward the development of smart ophthalmic diagnostic and surgical tools. Here, we provide an overview of current approaches applying MSI technology to ocular pathology.
Collapse
Affiliation(s)
- Hannah E Bowrey
- Brain Health Institute, Rutgers University, New Brunswick, NJ, USA
| | - David M Anderson
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Patrick Pallitto
- Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ, USA
| | - Danielle B Gutierrez
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Jie Fan
- Department of Ophthalmology, Medical University of South Carolina, Charleston, SC, USA
| | - Rosalie K Crouch
- Department of Ophthalmology, Medical University of South Carolina, Charleston, SC, USA
| | - Kevin L Schey
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Zsolt Ablonczy
- Department of Ophthalmology, Medical University of South Carolina, Charleston, SC, USA
| |
Collapse
|
16
|
Sparrow JR, Duncker T. Fundus Autofluorescence and RPE Lipofuscin in Age-Related Macular Degeneration. J Clin Med 2015; 3:1302-21. [PMID: 25774313 PMCID: PMC4358814 DOI: 10.3390/jcm3041302] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Genes that increase susceptibility to age-related macular degeneration (AMD) have been identified; however, since many individuals carrying these risk alleles do not develop disease, other contributors are involved. One additional factor, long implicated in the pathogenesis of AMD, is the lipofuscin of retinal pigment epithelium (RPE). The fluorophores that constitute RPE lipofuscin also serve as a source of autofluorescence (AF) that can be imaged by confocal laser ophthalmoscopy. The AF originating from lipofuscin is excited by the delivery of short wavelength (SW) light. A second autofluorescence is emitted from the melanin of RPE (and choroid) upon near-infrared (NIR-AF) excitation. SW-AF imaging is currently used in the clinical management of retinal disorders and the advantages of NIR-AF are increasingly recognized. Here we visit the damaging properties of RPE lipofuscin that could be significant when expressed on a background of genetic susceptibility. To advance interpretations of disease-related patterns of fundus AF in AMD, we also consider the photochemical and spectrophotometric features of the lipofuscin compounds responsible for generating the fluorescence emission.
Collapse
Affiliation(s)
- Janet R. Sparrow
- Department of Ophthalmology, Columbia University Medical Center, 635 W. 165th Street, New York, NY 10032, USA; E-Mail:
- Department of Pathology and Cell Biology, Columbia University Medical Center, 630 168th Street, New York, NY 10032, USA
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-212-305-0044
| | - Tobias Duncker
- Department of Ophthalmology, Columbia University Medical Center, 635 W. 165th Street, New York, NY 10032, USA; E-Mail:
| |
Collapse
|
17
|
Biarnés M, Arias L, Alonso J, Garcia M, Hijano M, Rodríguez A, Serrano A, Badal J, Muhtaseb H, Verdaguer P, Monés J. Increased Fundus Autofluorescence and Progression of Geographic Atrophy Secondary to Age-Related Macular Degeneration: The GAIN Study. Am J Ophthalmol 2015; 160:345-353.e5. [PMID: 25982972 DOI: 10.1016/j.ajo.2015.05.009] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 05/07/2015] [Accepted: 05/08/2015] [Indexed: 01/19/2023]
Abstract
PURPOSE To define the role of increased fundus autofluorescence (FAF), a surrogate for lipofuscin content, as a risk factor for progression of geographic atrophy (GA). DESIGN Prospective natural history cohort study, the GAIN (Characterization of geographic atrophy progression in patients with age-related macular degeneration). METHODS setting: Single-center study conducted in Barcelona, Spain. PATIENTS After screening of 211 patients, 109 eyes of 82 patients with GA secondary to age-related macular degeneration and a minimum follow-up of 6 months were included. OBSERVATION PROCEDURES Lipofuscin content was classified independently by 2 masked observers according to FAF patterns described previously. Bivariate, stratified, and multivariable analyses were used to explore the associations between GA growth and independent variables. Mediation analysis was used to evaluate the contribution of FAF patterns to GA progression. MAIN OUTCOME Progression of GA in mm(2)/year as measured with FAF. RESULTS Median follow-up was 18 months (range, 6-42). Median GA growth was 1.61 mm(2)/year. FAF, baseline area of atrophy, and time of follow-up were independently associated with GA progression (P < .004). FAF patterns and baseline area of atrophy were strongly associated (P < .0001), suggesting potential confounding. Mediation analysis suggested that most of the effect of FAF patterns on GA growth was actually caused by baseline area of atrophy. CONCLUSIONS FAF patterns, baseline area of atrophy, and time of follow-up were associated with GA progression. However, FAF patterns seem to be a consequence (not a cause) of enlarging atrophy and their effect on GA progression seems mostly driven by baseline area of atrophy.
Collapse
Affiliation(s)
- Marc Biarnés
- Institut de la màcula i de la retina (Centro Médico Teknon), Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain.
| | - Luis Arias
- Hospital Universitari de Bellvitge, Barcelona, Spain
| | - Jordi Alonso
- Universitat Pompeu Fabra (UPF), Barcelona, Spain; Health Services Research Unit, IMIM (Institut Hospital del Mar d'Investigacions Mèdiques), Barcelona, Spain; CIBER Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain
| | - Míriam Garcia
- Institut de la màcula i de la retina (Centro Médico Teknon), Barcelona, Spain
| | - Míriam Hijano
- Institut de la màcula i de la retina (Centro Médico Teknon), Barcelona, Spain
| | - Anabel Rodríguez
- Institut de la màcula i de la retina (Centro Médico Teknon), Barcelona, Spain
| | - Anna Serrano
- Institut de la màcula i de la retina (Centro Médico Teknon), Barcelona, Spain
| | - Josep Badal
- Institut de la màcula i de la retina (Centro Médico Teknon), Barcelona, Spain; Hospital Moisés Broggi, Barcelona, Spain
| | - Hussein Muhtaseb
- Institut de la màcula i de la retina (Centro Médico Teknon), Barcelona, Spain
| | - Paula Verdaguer
- Institut de la màcula i de la retina (Centro Médico Teknon), Barcelona, Spain
| | - Jordi Monés
- Institut de la màcula i de la retina (Centro Médico Teknon), Barcelona, Spain; Barcelona Macula Foundation, Barcelona, Spain
| |
Collapse
|
18
|
Crouch RK, Koutalos Y, Kono M, Schey K, Ablonczy Z. A2E and Lipofuscin. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 134:449-63. [PMID: 26310170 DOI: 10.1016/bs.pmbts.2015.06.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Lipofuscin is highly fluorescent material, formed in several tissues but best studied in the eye. The accumulation of lipofuscin in the retinal pigment epithelium (RPE) is a hallmark of aging in the eye and has been implicated in various retinal degenerations, including age-related macular degeneration. The bis-retinoid N-retinyl-N-retinylidene ethanolamine (A2E), formed from retinal, has been identified as a byproduct of the visual cycle, and numerous in vitro studies have found toxicity associated with this compound. The compound is known to accumulate in the RPE with age and was the first identified compound extracted from lipofuscin. Our studies have correlated the distribution of lipofuscin and A2E across the human and mouse RPE. Lipofuscin fluorescence was imaged in the RPE from human donors of various ages and from assorted mouse models. The spatial distribution of A2E was determined using matrix-assisted laser desorption-ionization imaging mass spectrometry on both flat-mounted and transversally sectioned RPE tissue. Our data support the clinical observations in humans of strong RPE fluorescence, increasing with age, in the central area of the RPE. However, there was no correlation between the distribution of A2E and lipofuscin, as the levels of A2E were highest in the far periphery and decreased toward the central region. Interestingly, in all the mouse models, A2E distribution and lipofuscin fluorescence correlate well. These data demonstrate that the accumulation of A2E is not responsible for the increase in lipofuscin fluorescence observed in the central RPE with aging in humans.
Collapse
Affiliation(s)
- Rosalie K Crouch
- Department of Ophthalmology, Albert Florens Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA.
| | - Yiannis Koutalos
- Department of Ophthalmology, Albert Florens Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Masahiro Kono
- Department of Ophthalmology, Albert Florens Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Kevin Schey
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA
| | - Zsolt Ablonczy
- Department of Ophthalmology, Albert Florens Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA
| |
Collapse
|
19
|
Marquioni-Ramella MD, Suburo AM. Photo-damage, photo-protection and age-related macular degeneration. Photochem Photobiol Sci 2015. [DOI: 10.1039/c5pp00188a] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The course of Age-related Macular Degeneration (AMD) is described as the effect of light (400–580 nm) on various molecular targets in photoreceptors and the retinal pigment epithelium (RPE). Photo-damage is followed by inflammation, increasing oxidative stress and, probably, unveiling new photosensitive molecules.
Collapse
Affiliation(s)
| | - Angela M. Suburo
- Medicina Celular y Molecular
- Facultad de Ciencias Biomédicas
- Universidad Austral
- Pilar B1629AHJ
- Argentina
| |
Collapse
|
20
|
Smith RT, Post R, Johri A, Lee MD, Ablonczy Z, Curcio CA, Ach T, Sajda P. Simultaneous decomposition of multiple hyperspectral data sets: signal recovery of unknown fluorophores in the retinal pigment epithelium. BIOMEDICAL OPTICS EXPRESS 2014; 5:4171-85. [PMID: 25574430 PMCID: PMC4285597 DOI: 10.1364/boe.5.004171] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 08/17/2014] [Accepted: 11/01/2014] [Indexed: 05/17/2023]
Abstract
Upon excitation with different wavelengths of light, biological tissues emit distinct but related autofluorescence signals. We used non-negative matrix factorization (NMF) to simultaneously decompose co-registered hyperspectral emission data from human retinal pigment epithelium/Bruch's membrane specimens illuminated with 436 and 480 nm light. NMF analysis was initialized with Gaussian mixture model fits and constrained to provide identical abundance images for the two excitation wavelengths. Spectra recovered this way were smoother than those obtained separately; fluorophore abundances more clearly localized within tissue compartments. These studies provide evidence that leveraging multiple co-registered hyperspectral emission data sets is preferential for identifying biologically relevant fluorophore information.
Collapse
Affiliation(s)
- R. Theodore Smith
- Department of Ophthalmology, New York University School of Medicine, 462 First Avenue – NBV 5N18, New York, NY 10016,
USA
| | - Robert Post
- Department of Ophthalmology, New York University School of Medicine, 462 First Avenue – NBV 5N18, New York, NY 10016,
USA
| | - Ansh Johri
- Department of Ophthalmology, New York University School of Medicine, 462 First Avenue – NBV 5N18, New York, NY 10016,
USA
| | - Michele D. Lee
- Department of Ophthalmology, New York University School of Medicine, 462 First Avenue – NBV 5N18, New York, NY 10016,
USA
| | - Zsolt Ablonczy
- Department of Ophthalmology, Medical University of South Carolina, 167 Ashley Avenue MSC676, Charleston, SC 29425,
USA
| | - Christine A. Curcio
- Department of Ophthalmology, University of Alabama at Birmingham School of Medicine, 1670 University Boulevard, Volker Hall Room 360, Birmingham, AL 35294,
USA
| | - Thomas Ach
- Department of Ophthalmology, University of Alabama at Birmingham School of Medicine, 1670 University Boulevard, Volker Hall Room 360, Birmingham, AL 35294,
USA
| | - Paul Sajda
- Department of Biomedical Engineering, Columbia University, 500 West 120th Street, 351 Engineering Terrace, New York, NY 10027,
USA
| |
Collapse
|
21
|
Abstract
To fully understand the drug mechanism of action of new chemical entities, pharmacologists need to acquire confident and precise data in pharmacokinetics and in pharmacodynamics and build strong pharmacokinetic/pharmacodynamic relationships. Target engagement in evaluating new chemical entities provides the basis for treatment efficacy. Classical technologies are sometimes limited or inefficient to provide these precise data; however, label-free MS imaging technology is able to provide these molecular features, spatial distributions, quantification and metabolomics data. Important considerations for imaging biological sections are described. Various applications in pharmacology are presented across different therapeutic areas, where MS imaging answers crucial drug discovery and preclinical development needs.
Collapse
|
22
|
Palczewska G, Golczak M, Williams DR, Hunter JJ, Palczewski K. Endogenous fluorophores enable two-photon imaging of the primate eye. Invest Ophthalmol Vis Sci 2014; 55:4438-47. [PMID: 24970255 DOI: 10.1167/iovs.14-14395] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
PURPOSE Noninvasive two-photon imaging of a living mammalian eye can reveal details of molecular processes in the retina and RPE. Retinyl esters and all-trans-retinal condensation products are two types of retinoid fluorophores present in these tissues. We measured the content of these two types of retinoids in monkey and human eyes to validate the potential of two-photon imaging for monitoring retinoid changes in human eyes. METHODS Two-photon microscopy (TPM) was used to visualize excised retina from monkey eyes. Retinoid composition and content in human and monkey eyes were quantified by HPLC and mass spectrometry (MS). RESULTS Clear images of inner and outer segments of rods and cones were obtained in primate eyes at different eccentricities. Fluorescence spectra from outer segments revealed a maximum emission at 480 nm indicative of retinols and their esters. In cynomolgus monkey and human retinal extracts, retinyl esters existed predominantly in the 11-cis configuration along with notable levels of 11-cis-retinol, a characteristic of cone-enriched retinas. Average amounts of di-retinoid-pyridinium-ethanolamine (A2E) in primate and human eyes were 160 and 225 pmol/eye, respectively. CONCLUSIONS These data show that human retina contains sufficient amounts of retinoids for two-photon excitation imaging. Greater amounts of 11-cis-retinyl esters relative to rodent retinas contribute to the fluorescence signal from both monkey and human eyes. These observations indicate that TPM imaging found effective in mice could detect early age- and disease-related changes in human retina.
Collapse
Affiliation(s)
| | - Marcin Golczak
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, United States
| | - David R Williams
- Center for Visual Science, University of Rochester, Rochester, New York, United States The Institute of Optics, University of Rochester, Rochester, New York, United States
| | - Jennifer J Hunter
- Center for Visual Science, University of Rochester, Rochester, New York, United States Flaum Eye Institute, University of Rochester, Rochester, New York, United States Department of Biomedical Engineering, University of Rochester, Rochester, New York, United States
| | - Krzysztof Palczewski
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, United States
| |
Collapse
|
23
|
Poliakov E, Strunnikova NV, Jiang JK, Martinez B, Parikh T, Lakkaraju A, Thomas C, Brooks BP, Redmond TM. Multiple A2E treatments lead to melanization of rod outer segment-challenged ARPE-19 cells. Mol Vis 2014; 20:285-300. [PMID: 24644403 PMCID: PMC3955416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Accepted: 03/11/2014] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Daily phagocytosis of outer segments (OSs) and retinoid recycling by the RPE lead to the accumulation of storage bodies in the RPE containing autofluorescent lipofuscin, which consists of lipids and bisretinoids such as A2E and its oxidation products. Accumulation of A2E and its oxidation products is implicated in the pathogenesis of several retinal degenerative diseases. However, A2E accumulates in the RPE during normal aging. In this study, we used a cell model to determine the homeostatic mechanisms of RPE cells in response to A2E accumulation. METHODS To distinguish between pathologic and normal responses of the RPE to A2E accumulation, we treated established ARPE-19 cells (cultured for 3 weeks after reaching confluence) with low micromolar amounts of A2E for several weeks. We compared the lysosomal function, lysosomal pH, degree of OS digestion, and melanization of the treated cells to untreated control cells in response to a challenge of purified rod OSs (ROSs). A2E was analyzed with high-performance liquid chromatography (HPLC); and A2E and melanin were identified with mass spectrometry. RESULTS We found that post-confluent ARPE-19 cells took up and accumulated A2E under dim light conditions. Spectral analysis of the HPLC separations and mass spectrometry showed that A2E-fed cells contained A2E and oxidized A2E (furan-A2E). A2E accumulation led to a modest increase (up to 0.25 unit) in lysosomal pH in these cells. The specific activity of cathepsin D and lysosomal acid phosphatase was reduced in the A2E-treated cells, but ROS degradation was not impaired. We found that, upon challenge with ROSs, melanin pigment was induced in the lysosomal fraction of the A2E-treated ARPE-19 cells. Thus, the ARPE-19 cells responded to the A2E treatment and ROS challenge by producing a melanin-containing lysosome fraction. We speculate that this prevents them from becoming impaired in OS processing. CONCLUSIONS We used a modified ARPE-19 cell model in which melanization was elicited as a response to chronic accumulation of A2E. We found that although A2E treatment led, as has been previously reported, to modest lysosomal alkalinization and lysosomal impairment of ARPE-19 cells, a potential homeostatic mechanism may involve production of a special type of lysosomes containing melanin.
Collapse
Affiliation(s)
- Eugenia Poliakov
- Laboratory of Retinal Cell and Molecular Biology, NEI, NIH, Bethesda, MD
| | | | - Jian-kang Jiang
- NIH Chemical Genomics Center, National Center for Advancing Translational Sciences, NIH, Rockville, MD
| | - Bianca Martinez
- Laboratory of Retinal Cell and Molecular Biology, NEI, NIH, Bethesda, MD
| | - Toral Parikh
- Laboratory of Retinal Cell and Molecular Biology, NEI, NIH, Bethesda, MD
| | - Aparna Lakkaraju
- Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI
| | - Craig Thomas
- NIH Chemical Genomics Center, National Center for Advancing Translational Sciences, NIH, Rockville, MD
| | - Brian P. Brooks
- Ophthalmic Genetics and Visual Function Branch, NEI, NIH, Bethesda, MD
| | - T. Michael Redmond
- Laboratory of Retinal Cell and Molecular Biology, NEI, NIH, Bethesda, MD
| |
Collapse
|
24
|
Ablonczy Z, Smith N, Anderson DM, Grey AC, Spraggins J, Koutalos Y, Schey KL, Crouch RK. The utilization of fluorescence to identify the components of lipofuscin by imaging mass spectrometry. Proteomics 2014; 14:936-44. [PMID: 24453194 DOI: 10.1002/pmic.201300406] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2013] [Revised: 12/16/2013] [Accepted: 12/21/2013] [Indexed: 11/08/2022]
Abstract
Lipofuscin, an aging marker in the retinal pigment epithelium (RPE) associated with the development of age-related macular degeneration, is primarily characterized by its fluorescence. The most abundant component of RPE lipofuscin is N-retinylidene-N-retinylethanolamine (A2E) but its exact composition is not known due to the complexity of the RPE extract. In this study, we utilized MALDI imaging to find potential molecules responsible for lipofuscin fluorescence in RPE tissue from Abca4(-/-) , Sv129, and C57Bl6/J mice aged 2 and 6 months. To assert relationships, the individual images in the MALDI imaging datasets were correlated with lipofuscin fluorescence recorded from the same tissues following proper registration. Spatial correlation information, which is usually lost in bioanalytics, pinpointed a relatively small number of potential lipofuscin components. The comparison of four samples in each condition further limited the possibility of false positives and provided various new, age- and strain-specific targets. Validating the usefulness of the fluorescence-enhanced imaging strategy, many known adducts of A2E were identified in the short list of lipofuscin components. These results provided evidence that mass spectrometric imaging can be utilized as a tool to begin to identify the molecular substructure of clinically-relevant diagnostic information.
Collapse
Affiliation(s)
- Zsolt Ablonczy
- Department of Ophthalmology, Medical University of South Carolina, Charleston, SC, USA
| | | | | | | | | | | | | | | |
Collapse
|
25
|
Zemski Berry KA, Gordon WC, Murphy RC, Bazan NG. Spatial organization of lipids in the human retina and optic nerve by MALDI imaging mass spectrometry. J Lipid Res 2013; 55:504-15. [PMID: 24367044 DOI: 10.1194/jlr.m044990] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
MALDI imaging mass spectrometry (IMS) was used to characterize lipid species within sections of human eyes. Common phospholipids that are abundant in most tissues were not highly localized and observed throughout the accessory tissue, optic nerve, and retina. Triacylglycerols were highly localized in accessory tissue, whereas sulfatide and plasmalogen glycerophosphoethanolamine (PE) lipids with a monounsaturated fatty acid were found enriched in the optic nerve. Additionally, several lipids were associated solely with the inner retina, photoreceptors, or retinal pigment epithelium (RPE); a plasmalogen PE lipid containing DHA (22:6), PE(P-18:0/22:6), was present exclusively in the inner retina, and DHA-containing glycerophosphatidylcholine (PC) and PE lipids were found solely in photoreceptors. PC lipids containing very long chain (VLC)-PUFAs were detected in photoreceptors despite their low abundance in the retina. Ceramide lipids and the bis-retinoid, N-retinylidene-N-retinylethanolamine, was tentatively identified and found only in the RPE. This MALDI IMS study readily revealed the location of many lipids that have been associated with degenerative retinal diseases. Complex lipid localization within retinal tissue provides a global view of lipid organization and initial evidence for specific functions in localized regions, offering opportunities to assess their significance in retinal diseases, such as macular degeneration, where lipids have been implicated in the disease process.
Collapse
Affiliation(s)
- Karin A Zemski Berry
- Department of Pharmacology, University of Colorado Denver, Aurora, CO 80045; and
| | | | | | | |
Collapse
|
26
|
Affiliation(s)
- Johannes von Lintig
- Case Western Reserve University, School of Medicine, Department of Pharmacology, Wood Bldg. 333, USA.
| | | |
Collapse
|