Contributions of ocular surface components to matrix-metalloproteinases (MMP)-2 and MMP-9 in feline tears following corneal epithelial wounding

Andrea Petznick, Michele C. Madigan, Qian Garrett, Deborah F. Sweeney, Margaret D. M. Evans

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    23 Citations (Scopus)

    Abstract

    Purpose: This study investigated ocular surface components that contribute to matrix-metalloproteinase (MMP)-2 and MMP-9 found in tears following corneal epithelial wounding. Methods: Laboratory short-haired cats underwent corneal epithelial debridement in one randomly chosen eye (n = 18). Eye-flush tears were collected at baseline and during various healing stages. Procedural control eyes (identical experimental protocol as wounded eyes except for wounding, n = 5) served as controls for tear analysis. MMP activity was analyzed in tears using gelatin zymography. MMP staining patterns were evaluated in ocular tissues using immunohistochemistry and used to determine MMP expression sites responsible for tear-derived MMPs. Results: The proMMP-2 and proMMP-9 activity in tears was highest in wounded and procedural control eyes during epithelial migration (8 to 36 hours post-wounding). Wounded eyes showed significantly higher proMMP-9 in tears only during and after epithelial restratification (day 3 to 4 and day 7 to 28 post-wounding, respectively) as compared to procedural controls (p<0.05). Tears from wounded and procedural control eyes showed no statistical differences for proMMP- 2 and MMP-9 (p>0.05). Immunohistochemistry showed increased MMP-2 and MMP-9 expression in the cornea during epithelial migration and wound closure. The conjunctival epithelium exhibited highest levels of both MMPs during wound closure, while MMP-9 expression was reduced in conjunctival goblet cells during corneal epithelial migration followed by complete absence of the cells during wound closure. The immunostaining for both MMPs was elevated in the lacrimal gland during corneal healing, with little/no change in the meibomian glands. Conjunctival-associated lymphoid tissue (CALT) showed weak MMP-2 and intense MMP-9 staining. Conclusions: Following wounding, migrating corneal epithelium contributed little to the observed MMP levels in tears. The major sources assessed in the present study for tear-derived MMP-2 and MMP-9 following corneal wounding are the lacrimal gland and CALT. Other sources included stromal keratocytes and conjunctiva with goblet cells.
    Original languageEnglish
    Article numbere71948
    Number of pages9
    JournalPLoS One
    Volume8
    Issue number8
    DOIs
    Publication statusPublished - 2013

    Open Access - Access Right Statement

    Copyright: 2013 Petznick et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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