Background: Genetic manipulation of the donor cornea ex vivo prior to transplantation may allow modulation of the allogeneic immune response following penetrating keratopasty. In this study we investigated the effect of adenovirus-mediated gene transfer of the Th2 cytokine interleukin-4 (IL-4) to rat corneas in an experimental keratoplasty model.
Methods: Ex vivo manipulation of Wistar-Furth rat corneas was performed using E1/E3-deleted adenoviral vectors transferring the gene for rat IL-4 (AdrIL-4) under control of the CMV promoter. Following transfection with AdrIL-4 (2 x 10(8) pfu) in DMEM/2% FCS for 3 h, donor corneas were transplanted in MHC class I/II-incompatible Lewis rats. Fifty-two Lewis rats were randomly assigned to receive either nontransfected grafts (n=32), AdrIL-4-transfected grafts (n=8), or syngeneic grafts (n=12).
Results: The rejection rate of AdrIL-4-transfected grafts (85.7%) could not be reduced as compared to controls (62.9%). In addition, the mean survival time of AdrIL-4-transfected grafts (12.6+/-4.5 days) did not differ (P>0.05) from that for untreated transplants (14.1+/-3.8 days).
Conclusions: Our results indicate that overexpression of IL-4 is not sufficient to reduce the rejection rate of corneal allografts in an experimental keratoplasty model. Further investigations are necessary to identify the reasons for failure and establish more efficient modulatory approaches.