Topical interleukin 1 receptor antagonist promotes corneal transplant survival

Background. Interleukin (IL)-1 is a potent proinflammatory cytokine that plays a critical role in initiating and maintaining immunogenic inflammation. We performed a series of experiments to determine whether the topical application of IL-1 receptor antagonist (IL-1ra) can prolong corneal transplant survival in the murine model of orthotopic allotransplantation. Methods. For all experiments, C57BL/6 corneas were transplanted into BALB/c (major histocompatibility and minor histocompatibility-disparate) eyes. ''High-risk'' transplants were transplants that had been sutured into BALB/c recipient beds with corneal neovascularization induced by placement of three interrupted sutures in the host cornea 2 weeks earlier. Both risk groups were divided in a masked fashion into treatment subgroups that received either 20 mg/ml of IL-1ra mixed in 0.2% sodium hyaluronate vehicle (n=28) or placebo alone (n=25). All transplants were evaluated for 8 weeks after surgery for signs of rejection. At the end of follow-up, corneal specimens were processed for enumeration of Langerhans cells and histopathological evaluation. Results. Survival rates of both normal-risk and highrisk transplants increased significantly among the IL-1ra-treated animals compared with untreated controls by both stratified Mantel-Haenszel (P=0.02) and KapIan-Meier survival (P=0.03) analyses. Furthermore, both normal- and high-risk IL-1ra-treated grafts had significantly less inflammation and Langerhans cells infiltration compared with untreated controls. Conclusions. Topical treatment with IL-1ra has a significantly positive effect in promoting corneal allograft survival.