A new model of orthotopic penetrating corneal transplantation in the sheep: graft survival, phenotypes of graft-infiltrating cells and local cytokine production

Aust N Z J Ophthalmol. 1999 Apr;27(2):127-35. doi: 10.1046/j.1440-1606.1999.00171.x.

Abstract

Background: Orthotopic penetrating keratoplasty in the sheep was developed as an outbred preclinical model to allow correlation of the cellular infiltrate during graft rejection with local production of cytokine mRNA.

Methods: Penetrating corneal autografts and allografts were performed in Merino sheep. Graft outcome was followed at the slit-lamp. Corneal infiltrates were examined by immunoperoxidase staining on postmortem specimens. Cytokine mRNA was detected by polymerase chain reaction.

Results: Corneal autografts survived indefinitely. Allografts became vascularized and underwent rejection at a median of 20 days postgraft. Both endothelial and epithelial rejection lines were observed. Immunohistochemical staining of rejecting grafts showed up-regulation of major histocompatibility complex class I molecules on corneal graft epithelium, damaged or absent graft endothelium and a marked, predominantly mononuclear cell infiltrate. CD4-positive T cells were observed in the graft within 2 days of the onset of rejection, followed several days later by CD8-positive T cells. Messenger RNA transcripts for interleukin (IL)-2, tumour necrosis factor (TNF)-alpha and IL-10 (but not for interferon (IFN)-gamma or IL-4) were found in autografted corneas. Proportionately, more allografts than autografts contained transcripts for IL-2 and TNF-alpha, and IFN-gamma was detected in three of four allografts.

Conclusions: Corneal graft rejection in the sheep is macroscopically and histologically similar to human corneal graft rejection. Allografts become infiltrated by both CD4- and CD8-positive T cells and local production of pro-inflammatory cytokines occurs during graft rejection.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cornea / metabolism*
  • Cornea / pathology*
  • Corneal Transplantation / methods*
  • Cytokines / biosynthesis*
  • Cytokines / genetics
  • Female
  • Graft Survival / physiology*
  • Immunohistochemistry
  • Phenotype
  • RNA, Messenger / metabolism
  • Sheep

Substances

  • Cytokines
  • RNA, Messenger