Epithelial injury induces keratocyte apoptosis: Hypothesized role for the interleukin-1 system in the modulation of corneal tissue organization and wound healing

Steven E. Wilson, Yu Guang He, Jian Weng, Qian Li, Alasdair W. McDowall, Mark Vital, Eric L. Chwang

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Abstract

The purpose of this study was to determine the role of programmed cell death (apoptosis) in the disappearance of keratocytes beneath an epithelial debridement wound in the cornea and to investigate a potential role of interleukin-1 (IL-1) in induction of apoptosis in stromal fibroblasts in vitro and keratocytes in vivo. Keratocyte and stromal fibroblast cell morphology was examined in wounded and unwounded mouse corneas using transmission electron microscopy. Nuclear DNA fragmentation was detected with the TUNEL assay for 3'-hydroxyl DNA ends. The effect of IL-1 on keratocytes in vivo was determined by microinjection of IL-1 alpha into the central corneal stroma via a limbal entry site. The in vitro effects of interleukin-1 alpha (IL-1 alpha) and interleukin-1 beta (IL-1 beta) were determined with primary cultures of human corneal stromal and dermal-fibroblasts. Cell shrinkage, blebbing with formation of membrane bound bodies, condensation and fragmentation of the chromatin, and DNA fragmentation, consistent with apoptosis were detected in anterior stromal keratocytes after epithelial scrape wounds. Thus, disappearance of keratocytes from the underlying stroma following epithelial debridement is mediated by apoptosis. Microinjection of IL-1 alpha into the central stroma of the mouse cornea caused a redistribution of keratocytes in the stroma via apoptosis and, possibly, negative chemotaxis. IL-1 alpha and IL-1 beta induced apoptosis in corneal stromal and dermal fibroblasts in vitro. The epithelial/endothelial-stromal IL-1 system may mediate corneal tissue organization and responses to mechanical- and pathogen-induced injury through induction of keratocyte apoptosis. Keratocyte apoptosis is likely an initiating event in wound healing following corneal surgery. We hypothesize that derangement's in this system may have a role in the pathogenesis of keratoconus and other diseases of the cornea.

Original languageEnglish (US)
Pages (from-to)325-338
Number of pages14
JournalExperimental Eye Research
Volume62
Issue number4
DOIs
StatePublished - Apr 1996

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Keywords

  • Apoptosis
  • Cornea
  • Fibroblasts
  • Interleukin-1
  • Keratoconus
  • Keratocytes
  • Programmed cell death
  • Skin
  • Viral infection
  • Wound healing

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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