Effect of Tacrolimus on Chemokine Production by Corneal Myofibroblasts via Toll-Like Receptors, Compared With Cyclosporine and Dexamethasone

Purpose: To investigate the effect of tacrolimus on chemokine production by corneal myofibroblasts compared with that of cyclosporine or dexamethasone. Methods: We investigated the expression of FK506-binding protein 12, calcineurin, and nuclear factor of activated T cells in corneal myofibroblasts by immunocytochemistry and flow cytometry. Next, we investigated whether toll-like receptor 9 ligand, CpG-DNA, or toll-like receptor 3 ligand, poly (I:C), induced the production of chemokines such as interleukin (IL) 8, Gro-alpha, and IL-6 by corneal myofibroblasts using enzyme-linked immunosorbent assay. Finally, we assessed the effect of tacrolimus on the production of these chemokines compared with that of cyclosporine or dexamethasone. Results: FK506-binding protein 12, calcineurin, and nuclear factor of activated T cells were constantly expressed by cultured corneal myofibroblasts. CpG DNA and poly (I:C) enhanced the production of IL-8, Gro-alpha, and IL-6 by corneal myofibroblasts. At a concentration 10 nM/L or higher, dexamethasone strongly inhibited the production of these chemokines. In contrast, cyclosporine concentrations of 10 ng/mL or more enhanced the production of these chemokines by cells stimulated with poly (I:C). On the other hand, tacrolimus (at 10 ng/mL or more) inhibited the production of these chemokines by corneal myofibroblasts stimulated with poly (I:C) but not with CpG-DNA. Conclusions: These results suggest that tacrolimus and dexamethasone, but not cyclosporine, have a direct immunosuppressive effect on corneal myofibroblasts. Therefore, when inflammatory diseases of the ocular surface are treated by tacrolimus, especially in combination with steroids, caution with regard to the risk of corneal infection may be needed.