RESUMO
BackgroundCorneal graft reject is a major cause of corneal transplantation failure.Although many immune-suppressing drugs have been utilized to reduce the reject response,their adverse effects on organ and tissue are still insoluble.The tolerance induction of natural killer T (NKT) cells is currently under investigation.However,the study on the application of NKT cells in high risk corneal transplantation is seldom.ObjectiveThe present study was to explore the effects of α-GalCer-activated NKT cella on allografts survival after high-risk corneal transplantation surgery via retro-bubar injection.Methods The lymphocytes were picked up from the spleen of SPF Lewis rats and cultured in RPMI 1640 medium with 100 mg/L α-GalCer.After one week,NKT cells were sorted by the FACSVantage system as CD161+ TCR-α+ cell from the lymphocytes with the cell densities 5×106/ml.Ten SPF Fisher344 rats were used to prepare the donor corneas,and 20 Lewis rats served as recipients.The high risk corneal transplantation models were created by corneal suturing in 20 recipient rats.Penetrating keratoplasty (PKP) was performed in the model rats.0.1 ml NKT cells or the same volume of normal saline solution were retro-bubarly injected at the end of surgery respectively.The corneal allografts were observed and scored based on Holland criteria at the three-day interval under the slit lamp for 30 days.Two weeks after surgery,three rats from each group were sacrificed by excessive anesthesia method and the eyeballs were obtained for histopathological examination.The inflammatory cell infiltration ( CD4+ and CD8+ ) in grafts was evaluated by immunochemistry and flow cytometry.The use of the animals complied with the Statement of ARVO.ResultsThe mean survival time of the allografts was (7.90± 1.37) days in normal saline solution group and (14.70± 1.49) days in NKT cell group,showing a statistically significant difference between the two groups ( t =10.61,P =0.00 ).Two weeks after surgery,all the allografts showed the severe opacity with lots of new blood vessels and edema in normal saline solution group.However,the corneal grafts were clear in NKT cell group.Abundant CD4+ and CD8+T lymphocytes were seen in the allografts in normal saline solution group,but the inflammatory cells were obviously less in NKT cell group.The percentage of NKT cells in the spleen was (5.67±0.25)％ in NKT cell group and ( 1.21±0.19)％ in normal saline solution group ( t =8.43,P =0.00 ).Conclusionsα-GalCer-activated NKT cells can prolong the survival time of allografts in high-risk corneal transplantation.Retro-bubar injection of α-GalCer-activated NKT cells probably is a new approach to the prevention of the rejection of corneal transplantation.