Dose-dependent therapeutic effects of topical 1,25 OH-vitamin D3 on corneal wound healing

Conflicting results have been reported regarding the effects of 1,25 OH-vitamin D₃ on corneal wound healing. Therefore, we undertook this study to determine whether the observed differences are dose related. The dose-dependent effects of 1,25 OH-vitamin D₃ on corneal wound healing were evaluated using scratch assays on human corneal limbal-epithelial cells (HCLEs) and in vivo mouse corneal epithelial debridement. To evaluate the anti-inflammatory effects of 1,25 OH-vitamin D₃, macrophages were stimulated by a Toll-Like Receptor (TLR) ligand followed by treatment with the 10^-6 M, 10^-7 M and 10^-8 M 1,25 OH-vitamin D₃. 10^-7 M 1,25 OH-vitamin D₃ induced faster scratch wound closure compared with the other concentrations of 1,25 OH-vitamin D₃ tested (10^-6 M and 10^-8 M), and 0.02% ethanol as a control (85.8 ± 2.6%, 33.9 ± 6.74%, 32.6 ± 3.35%, and 31.6 ± 3.99%, respectively, P < 0.0001). Single-time treatment with 10^-7 M 1,25 OH-vitamin D₃ also significantly improved the healing of mouse corneal epithelial wound compared to multiple treatments and control (74.1 ± 17.3% vs. 52.4 ± 11.6% and 45.8 ± 13.4%, respectively). Polyinosinic: polycytidylic acid (poly [I:C])-stimulated macrophage cells and 10^-7 M 1,25 OH-vitamin D₃ significantly decreased gene expression of ICAM1, TLR3, IL6, IL8, and TNFα (P < 0.0001). Our results suggest the dose-dependent therapeutic effect of 1,25 OH-vitamin D₃ in corneal wound healing which can be potentially used as a non-invasive option in the treatment of corneal wounds.