April 2014
Volume 55, Issue 13
Free
ARVO Annual Meeting Abstract  |   April 2014
Lens epithelial cells use phagocytosis as a mechanism to remove apoptotic cellular debris
Author Affiliations & Notes
  • Daniel Chauss
    Biomedical Sciences, Florida Atlantic University, Boca Raton, FL
  • Lisa A Brennan
    Biomedical Sciences, Florida Atlantic University, Boca Raton, FL
  • Bettina Teng
    Biomedical Sciences, Florida Atlantic University, Boca Raton, FL
  • Marc Kantorow
    Biomedical Sciences, Florida Atlantic University, Boca Raton, FL
  • Footnotes
    Commercial Relationships Daniel Chauss, None; Lisa Brennan, None; Bettina Teng, None; Marc Kantorow, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science April 2014, Vol.55, 3568. doi:
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      Daniel Chauss, Lisa A Brennan, Bettina Teng, Marc Kantorow; Lens epithelial cells use phagocytosis as a mechanism to remove apoptotic cellular debris. Invest. Ophthalmol. Vis. Sci. 2014;55(13):3568.

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

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Abstract

Purpose: Phagocytosis has been proposed to clear apoptotic cells and toxic cellular debris resulting from exogenous insult. The eye lens is constantly exposed to UV-light and oxidative insults that result in lens epithelial cell apoptosis, loss of lens homeostasis and cataract formation. We hypothesized that lens epithelial cells could use phagocytosis to remove adjacent apoptotic cells and debris. We therefore evaluated the ability of lens epithelial cells to phagocytize a wide-range of substrates and we identified at least one receptor required for lens epithelial cell phagocytosis.

Methods: Embryonic chicken primary lens epithelial cells, human SRA04/01 cells and embryonic chicken lens epithelium explants were cultured in the presence of either 2μm FITC conjugated fluorospheres, attenuated FITC-labeled bacterial debris, 103QeGFP Huntingtin protein aggregates or fluorescently-labeled apoptotic lens epithelial cell debris and monitored for substrate binding and internalization by confocal microscopy and transmission electron microscopy (TEM). The expression of specific phagocytosis receptors was evaluated by RT-PCR, western analysis and immunohistochemistry. A function-blocking antibody against integrin αVβ5 was used to determine the requirement of αVβ5 for lens epithelial cell phagocytosis.

Results: Primary chicken lens epithelial cells and SRA04/01 cells phagocytize all substrates tested including apoptotic lens epithelial cell debris. Lens epithelial cell explants phagocytized fluorospheres. Phagocytosis was confirmed by TEM. Two phagocytosis receptors (integrin αVβ5 and CD36) co-localized with substrates in primary chicken lens epithelial cells. Functional loss of αVβ5 resulted in impaired phagocytosis by primary chicken lens epithelial cells. Oxidative stress treatment of lens epithelial cells resulted in increased expression of the ITGAV subunit of integrin αVβ5.

Conclusions: The cells of the lens epithelium are capable of phagocytizing multiple substrates including apoptotic debris of lens epithelial cells likely through an integrin-dependent mechanism. These results provide evidence that the lens epithelium is a dynamic structure that uses phagocytosis to maintain its cell population and thereby ensure lens homeostasis and transparency.

Keywords: 645 phagocytosis and killing • 634 oxidation/oxidative or free radical damage  
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