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Characterization of Retinal Pigment Epithelial Melanin and Degraded Synthetic Melanin Using Mass Spectrometry and In

Sally M Yacout1, Kelsey L McIlwain1, Shama P Mirza2

  • 1Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, IL.

Photochemistry and Photobiology
|May 13, 2018
PubMed

Insights

Aging causes melanin loss in retinal cells, potentially worsening eye diseases like AMD. This study shows melanin protects against oxidative stress, but its degradation may increase damage and disease risk.

Area of Science:

  • Ophthalmology
  • Cell Biology
  • Biochemistry

Background:

  • Melanin in retinal pigment epithelial (RPE) cells decreases with age.
  • Melanin's degradation may contribute to retinal diseases like age-related macular degeneration (AMD) by depleting antioxidant capacity.
  • Oxidative damage to melanin can generate harmful reactive oxygen species (ROS) and byproducts.

Purpose of the Study:

  • To characterize age-related structural and functional changes in RPE melanin.
  • To investigate the role of melanin in protecting RPE cells from oxidative stress.
  • To understand how melanin degradation products contribute to RPE cell damage.

Main Methods:

  • MALDI mass spectrometry to analyze human donor RPE melanin degradation.
  • In vitro studies using ARPE-19 cells to assess melanin's photo-reactivity.
  • Exposure of pigmented cells to blue light and UV-B radiation to measure ROS and nitric oxide production.

Main Results:

  • Melanin-pigmented cells showed significant protection against blue light-induced intracellular ROS (P < 0.0001).
  • UV-B exposure increased nitric oxide production in aged human melanin-pigmented cells (P < 0.001).
  • Characterization of peroxide-treated synthetic melanin identified potential RPE cell-damaging degradation products.

Conclusions:

  • RPE melanin plays a crucial protective role against oxidative stress.
  • Melanin degradation with age is linked to increased cellular damage and may be a risk factor for AMD.
  • Further research into melanin degradation products is needed to understand RPE pathology.

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