Accumulated Eye Iron

Discussion in 'Eye-Care' started by ironjustice, Jan 18, 2009.

  1. ironjustice

    ironjustice Guest

    Dysfunction of the retinal pigment epithelium with age: increased iron
    decreases phagocytosis and lysosomal activity
    Huiyi Chen 1*, Thomas J Lukas 2, Nga Du 1, Genn Suyeoka 1, and Arthur
    H. Neufeld 1
    1 Ophthalmology, Northwestern University School of Medicine, Chicago,
    Illinois, United States
    2 Ophthalmology, Northwestern University, Chicago, Illinois, United
    States
    * To whom correspondence should be addressed. E-mail: huiyi-
    .

    Abstract

    PURPOSE.
    Iron accumulation with age in the retinal pigment epithelium (RPE) may
    be one important source of oxidative stress that contributes to age-
    related macular degeneration (AMD).
    We compared young and old rodent RPE/choroid to assess iron
    homeostasis during normal aging and the effects of increased iron on
    the functions of RPE cells. METHODS.
    The iron level, mRNA expression and protein level of iron regulatory
    molecules in RPE/choroid were quantitatively compared between young
    and old animals.
    To test effects of increased intracellular iron on the functions of
    RPE cells, in vitro ARPE-19 cells were treated with high iron and
    assessed for phagocytosis activity and lysosomal activity.
    RESULTS.
    The level of iron was significantly increased in the aged RPE/choroid.
    Ferritin and ceruloplasmin mRNAs were significantly increased in the
    aged RPE/choroid; whereas, transferrin, transferrin receptor and
    ferroportin mRNAs did not change with age. At the protein level,
    decreased transferrin and transferrin receptor, increased ferritin and
    ceruloplasmin, and unchanged ferroportin were observed in the aged RPE/
    choroids. Exposure of ARPE-19 cells to increased iron markedly
    decreased phagocytosis activity, interrupted cathepsin D processing
    and reduced the cathepsin D activity in RPE cells.
    CONCLUSIONS.
    In the RPE/choroid of old animals, there are iron accumulation and
    associated alterations in iron homeostasis.
    The iron accumulation with age may impair the phagocytosis and
    lysosomal functions of RPE cells in the aged RPE/choroid.
    Therefore, age-related changes of iron homeostasis in the RPE could
    increase the susceptibility of the tissue to genetic mutations
    associated with AMD.

    Key Words: age-related macular degeneration, oxidative damage,
    ARPE-19

    P<P, published online ahead of print January 17, 2009
    (Investigative Ophthalmology and Visual Science. )

    DOI: 10.1167/iovs.08-2850

    Copyright © 2009 by the Association for Research in Vision and
    Ophthalmology

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    ironjustice, Jan 18, 2009
    #1
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  2. ironjustice

    serebel Guest

    Must be a full moon.
     
    serebel, Jan 19, 2009
    #2
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