Aim: To observe the apoptosis of cells in rat corneal grafts at acute rejection phase and explore the effects of IL-1 receptor antagonist (IL-1ra) on cell apoptosis.
Methods: The penetrating corneal transplantation model was established. Corneal grafting was divided into four groups, namely, normal Wistar rat control group (no grafting, group A), isograft (Wistar rat-->Wistar rat, group B), allograft (Wistar rat-->SD rat) with normal saline treatment (group C) and allograft (Wistar rat-->SD rat) with IL-1ra treatment (group D). Cell apoptosis in corneal grafts was detected by TUNEL staining at 7 d, 10 d and 14 d after transplantation, and an automatic image analyzer was used to analyze the results, which were expressed as positive unit (PU). The changes of cellular ultrastructure in corneal grafts were observed under transmission electron microscope.
Results: (1)The average survival time of corneal grafts in C and D groups was (10.38+/-1.85) d and (13.56+/-1.94) d, respectively, with significant difference (P<0.01). (2)As compared with normal and non-rejected corneas, cell apoptosis and necrosis commonly existed in corneal grafts which rejection had occur. (3)In normal corneas, there were merely a very small number apoptotic cells in epithelial laminal, and apoptotic cells were found hardly in stromal laminal and endothelial cell layers. However, sporadic apoptotic cells were found in all layers of corneal grafts in B, C and D groups at 10 d after transplantation, the average PU being of no notably difference (P>0.05). Apoptosis obviously increased in nearby regions of wound and central area of corneal grafts in C and D groups, especially in C group. The apoptotic cells were distributed mainly in basal layer of epithelial cells and stroma of superficial layer.
Conclusion: Cell apoptosis plays an important role in corneal graft rejection reaction. IL-1ra treatment can prolong the survival time of corneal grafts by means of suppression of cell apoptosis in corneal grafts.