June 2020
Volume 61, Issue 7
Open Access
ARVO Annual Meeting Abstract  |   June 2020
Molecular characterization of retinal pigment epithelium (RPE) correlating to hyperreflective foci (HRF) in age-related macular degeneration (AMD)
Author Affiliations & Notes
  • Dongfeng Cao
    Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, Alabama, United States
  • Jeffrey Messinger
    Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, Alabama, United States
  • Roland Theodore Smith
    Ophthalmology, Mount Sinai School of Medicine, New York, New York, United States
  • Thomas Ach
    University Hospital Wurzburg, Germany
  • Christine Curcio
    Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, Alabama, United States
  • Footnotes
    Commercial Relationships   Dongfeng Cao, None; Jeffrey Messinger, None; Roland Smith, Ora Technologies (C); Thomas Ach, MacRegen Inc. (I); Christine Curcio, Genentech/ Hoffman LaRoche (F), Heidelberg Engineering (F), MacRegen Inc (I)
  • Footnotes
    Support  NIH R01EY027948 (CAC, TA, RTS), and R01EY015520 (RTS, CAC); Research to Prevent Blindness (New York, NY, USA) (CAC); EyeSight Foundation of Alabama (Birmingham, AL, USA) (CAC); International Retinal Research Foundation (Birmingham, AL, USA) (CAC); IZKF Würzburg (N-304, TA), and Dr. Werner Jackstadt Foundation (TA).
Investigative Ophthalmology & Visual Science June 2020, Vol.61, 1830. doi:
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      Dongfeng Cao, Jeffrey Messinger, Roland Theodore Smith, Thomas Ach, Christine Curcio; Molecular characterization of retinal pigment epithelium (RPE) correlating to hyperreflective foci (HRF) in age-related macular degeneration (AMD). Invest. Ophthalmol. Vis. Sci. 2020;61(7):1830.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : In histology and clinical optical coherence tomography (OCT), HRF in AMD correlate to anteriorly migrating RPE; in neovascular (nv)AMD, HRF also include lipid-filled cells. HRF confer high risk for progression to advanced AMD. To assess HRF functional repertoire, we probed 15 RPE phenotypes (PMID 28785769) for immune cell markers (CD68, CD163) and retinoid pathway proteins (RPE65, CRALBP).

Methods : Eyes of white donors (>80 years) were preserved by immersion in 4% paraformaldehyde (mean death-to-preservation, 3.9 hours). Ex vivoOCT scans (Spectralis, Heidelberg Engineering) were indexed to 12 µm-thick sections of posterior pole, which were stained with periodic acid Schiff hematoxylin for diagnosis, immuno-stained using enzymatic detection and a red substrate, and scanned with a 40X objective. RPE was recognized by abundant spindle-shape melanosomes and lipofuscin/ melanolipofuscin. Staining was assessed by one observer as 0 (none), 1 (some cells of a phenotype), 2 (all cells) and converted to percentage by dividing by the maximal allowable score for each phenotype. Positive controls were cells of inner retina and choroid (CD68, CD163) and Müller glia (CRALPB).

Results : In 4 normal and 16 AMD eyes (early-intermediate AMD, n=7; geographic atrophy, n=6; nvAMD, n=3), 13 RPE phenotypes were stained by 4 markers each, in at least 3 different eyes. Vitelliform and vacuolated cells were not seen. RPE65 and CRALBP immunoreactivity was intense in uniform and non-uniform RPE (age-normal, in a continuous layer) and rare (<5%) in any other phenotype at any AMD stage. In atrophic areas Müller glia were strongly labeled by CRALBP and dissociated RPE was unlabeled. CD68 and CD163 immunoreactivity appeared in some non-uniform RPE and in all abnormal phenotypes, including intraretinal RPE, with CD68 much more prominent than CD163.

Conclusions : This is the first attempt to probe functions of migrating RPE cells in AMD retinas. Immunoreactivity for CD68, a macrophage lysosome protein, in age-normal RPE layer, intraretinal RPE, and other phenotypes suggests that RPE cells transdifferentiate in situ then migrate. Loss of retinoid processing proteins in RPE and preservation in Müller glia supports a model of vulnerable rod vision and resilient cone vision due to glial sustenance. Markers for HRF will facilitate high-throughput discovery of their full repertoire.

This is a 2020 ARVO Annual Meeting abstract.

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