Role of costimulatory molecule Tim-1 in the immune reaction of corneal transplantation in rats / 中华实验眼科杂志

ABSTRACT

Background Corneal transplantation is the most reliable and effective means to treat the corneal blindness in the clinical,immune rejection is a major cause of corneal graft failure after the keratoplasty.Objective This study aimed to investigate the role of Tim-1 in the immune reaction following corneal transplantation in rats.Methods Forty clean female Wistar rats were randomized into normal control group,autologous corneal transplantation group and allogeneic corneal transplantation group.Penetrating corneal transplantation was performed with the Wistar rat donors and Wistar rat receipts in the autologous corneal transplantation group,while with the SD rat donors and Wistar rat receipts in the allogeneic corneal transplantation group.The corneal graft diameter was 3.5 mm and the plant bed diameter was 3.0 mm.The inflammatory response of the grafts was examined under the slit lamp microscope 7 days and 14 days after operation and scored based on the criteria of Larkin.Rejection index (RI),mean survival time and survival rate were calculated.The histopathological examination was performed 7 days and 14 days after surgery to evaluate the inflammatory manifestation,and the expressions of Tim-1 protein and mRNA were assayed by immnunochemistry and real-time fluorescence quantitative PCR (RT-qPCR)in the time points mentioned above.Results Mild edema of the grafts were found 7 days after operation in both the autologous corneal transplantation group and the allogeneic corneal transplantation group.In postoperative 14 days,the grafts were clear in the autologous corneal transplantation group,but the thickening,neovacularization and cloudy of the grafts were exhibited in the allogeneic corneal transplantation group.The survival rate of the grafts was 100％ in the autologous corneal transplantation group and that of the allogeneic corneal transplantation group was 0 with the survival time of (9.8±1.2) days.Histopathological examination revealed the stromal infiltration of inflammatory cells in both the autologous and allogeneic corneal transplantation groups in the seventh day,however,the inflammatory cells were obvious decreased in the autologous group but increased in the allogeneic corneal transplantation group in the fourteenth day.Immunochemistry showed a gradually declined positive cells for Tim-1 protein in the autologous corneal transplantation group,but the positive cells were exactly elevated in the allogeneic corneal transplantation group from 7 days through 14 days after operation;While only few positive cells were seen in the normal control group.The expression levels of Tim-1 mRNA in the grafts were 1.24 ± 0.03,5.85 ± 0.08 and 6.54 ± 0.20 in the normal control group,autologous corneal transplantation group and that of the allogeneic corneal transplantation group,respectively,in the seventh day,and in the fourteen day after operation,the expression level declined to 1.54 ±0.10 in the autologous corneal transplantation group and elevated to 8.62±0.24 in the allogeneic corneal transplantation group,showing significant differences among the different groups and various time points (Fgroup =3 277.590,P =0.000 ; Ftime =136.000,P =0.000).Conclusions Tim-1 may play an important role not only in the inflammatory response but also in the rejection reaction of the corneal transplantation.