Suppressive Role of Pigment Epithelium-derived Factor in a Rat Model of Corneal Allograft Rejection

Background. Immunological rejection is the most common reason for corneal transplantation failure. The importance of T cells in corneal allograft rejection is well demonstrated. Recent studies highlight that pigment epithelium-derived factor (PEDF) plays an immunoregulatory role in ocular diseases by enhancing the suppressive phenotype of regulatory T cells besides its other functions in neurotrophy and antiangiogenesis. Methods. The effects of PEDF on immune rejection were examined in rat models of corneal transplantation using slit-lamp microscope observation, immunohistochemistry, flow cytometry, and Western blot. In vitro, we demonstrated PEDF reduced alloreactive T-cell activation using real-time polymerase chain reaction, flow cytometry, and Western blot. Results. Topical administration of PEDF provided corneal transplantation rats with an improved graft survival rate of corneal allografts, reduced hemangiogenesis, and infiltration of immune cells in corneas, in particular, type 17 T helper cells while increased regulatory T cells. Moreover, nerve reinnervation within grafts was promoted in PEDF-treated recipient rats. In vitro, PEDF inhibited alloreactive T-cell activation via the c-Jun N-terminal kinase/c-Jun signaling pathway and upregulated the expressions of interleukin-10 and transforming growth factor-β, emphasizing the suppressive role of PEDF on immune responses. Conclusions. Our results underscore the feasibility of PEDF in alleviating corneal allograft rejection and further illustrate its potential in managing immune-related diseases.