title: Lipofuscin redistribution and loss accompanied by cytoskeletal stress in retinal pigment epithelium of eyes with age-related macular degeneration.
abstract: OBJECTIVE
  Lipofuscin (LF) and melanolipofuscin (MLF) of the retinal pigment epithelium (RPE) are the principal sources of autofluorescence (AF) signals in clinical fundus-AF imaging. Few details about the subcellular distribution of AF organelles in AMD are available. We describe the impact of aging and AMD on RPE morphology revealed by the distribution of AF LF/MLF granules and actin cytoskeleton in human tissues.
  
  
  METHODS
  Thirty-five RPE-Bruch's membrane flatmounts from 35 donors were prepared (postmortem: ≤4 hours). Ex vivo fundus examination at the time of accession revealed either absence of chorioretinal pathologies (10 tissues; mean age: 83.0 ± 2.6 years) or stages of AMD (25 tissues; 85.0 ± 5.8 years): early AMD, geographic atrophy, and late exudative AMD. Retinal pigment epithelium cytoskeleton was labeled with AlexaFluor647-Phalloidin. Tissues were imaged on a spinning-disk fluorescence microscope and a high-resolution structured illumination microscope.
  
  
  RESULTS
  Age-related macular degeneration impacts individual RPE cells by (1) lipofuscin redistribution by (i) degranulation (granule-by-granule loss) and/or (ii) aggregation and apparent shedding into the extracellular space; (2) enlarged RPE cell area and conversion from convex to irregular and sometimes concave polygons; and (3) cytoskeleton derangement including separations and breaks around subretinal deposits, thickening, and stress fibers.
  
  
  CONCLUSIONS
  We report an extensive and systematic en face analysis of LF/MLF-AF in AMD eyes. Redistribution and loss of AF granules are among the earliest AMD changes and could reduce fundus AF signal attributable to RPE at these locations. Data can enhance the interpretation of clinical fundus-AF and provide a basis for future quantitative studies.
authors.affiliation: University of Alabama at Birmingham Department of Ophthalmology, Birmingham, Alabama, United States 2University Hospital Würzburg, Department of Ophthalmology, Würzburg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Ach
authors.affiliation: Leibniz Institute of Photonic Technology, Jena, Germany 5King's College London, Randall Division of Cell & Molecular Biophysics, London, United Kingdom.
authors.forename: Elen
authors.initials: E
authors.lastname: Tolstik
authors.affiliation: University of Alabama at Birmingham Department of Ophthalmology, Birmingham, Alabama, United States.
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Messinger
authors.affiliation: University of Alabama at Birmingham Department of Ophthalmology, Birmingham, Alabama, United States.
authors.forename: Anna V
authors.initials: AV
authors.lastname: Zarubina
authors.affiliation: Leibniz Institute of Photonic Technology, Jena, Germany 5King's College London, Randall Division of Cell & Molecular Biophysics, London, United Kingdom.
authors.forename: Rainer
authors.initials: R
authors.lastname: Heintzmann
authors.affiliation: University of Alabama at Birmingham Department of Ophthalmology, Birmingham, Alabama, United States.
authors.forename: Christine A
authors.initials: CA
authors.lastname: Curcio
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D016570:Bruch Membrane / Q000378:metabolism / Q000473:pathology; D003599:Cytoskeleton; D005260:Female; D006801:Humans; D008062:Lipofuscin / Q000378:metabolism*; D008268:Macular Degeneration / Q000378:metabolism* / Q000473:pathology; D018613:Microscopy, Confocal; D055213:Retinal Pigment Epithelium / Q000378:metabolism* / Q000473:pathology; D012168:Retinal Pigments / Q000378:metabolism; D013050:Spectrometry, Fluorescence
chemical_list: D008062:Lipofuscin; D012168:Retinal Pigments