Abstract
Purpose:
Although the members of the galectin family of carbohydrate-binding proteins are thought to play a role in immune response and the regulation of allograft survival, little is known about the galectin expression signature in failed corneal grafts. The goal of this study was to compare the galectin expression pattern in the rejected and accepted murine corneal allografts.
Methods:
Using BALB/c mice as graft recipients and C57BL/6 mice as graft donors, a total of 57 transplants were performed. One week after transplantation, the grafts were scored for opacity by slit-lamp microscopy. Initially clear grafts which develop opacity score of 3+ or greater on postoperative week 4 were considered rejected. All grafted corneas were harvested on postoperative week 4, and their galectin expression was analyzed by Western blot and immunofluorescence staining.
Results:
As determined by Western blot analyses, galectins-1, -3, -7, -8 and -9 were expressed in normal corneas. Although, in both accepted and rejected grafts, protein expression levels of galectins-1, -3, -7, -8 and -9 were upregulated compared to normal corneas, there were distinct differences in the expression level of galectins-8 and -9 between accepted and rejected grafts. Galectin-8 was downregulated, whereas galectin-9 was upregulated in accepted grafts compared to rejected grafts. Consistent with these findings, in immunofluorescence staining, galectin-8 expression in accepted grafts was lower than in the stroma of rejected grafts, whereas galectin-9 immunoreactivity was stronger in accepted grafts compared to rejected grafts.
Conclusions:
Our findings that corneal allograft rejection is associated with increased galectin-8 expression and reduced galectin-9 expression, lead us to hypothesize that galectin-8 may reduce graft survival, whereas galectin-9 may promote graft survival. As a potential therapeutic intervention, inhibition of galectin-8 and/or treatment with exogenous galectin-9 may enhance corneal allograft survival rates.