The role of macrophage migration inhibitory factor in ocular surface disease pathogenesis after chemical burn in the murine eye

PURPOSE To evaluate the role of macrophage migration inhibitory factor (MIF) in the wound healing process following severe chemical burns to the ocular surface. METHODS Chemical burning of the ocular surface was induced in mice (C57BL/6) via the application of 0.1 M NaOH. Macrophage migration inhibitory factor (MIF), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) mRNA expression in the ocular surface and lacrimal gland was evaluated via real-time reverse transcription PCR on days 2, 7, and 30 after induction of the chemical burn. The expression of MIF protein in the ocular surface and lacrimal gland was evaluated via western blot analysis. Immunohistochemical staining was conducted to detect MIF and vasculoendothelial growth factor in the cornea during the wound healing process. The angiogenic role of MIF was further evaluated using an 8-0 polyglactin suture technique to induce corneal neovascularization. RESULTS MIF, TNF-α, and IL-1β mRNA expression were elevated significantly in the ocular surface up to day 30 after chemical burn induction. TNF-α alone was elevated in the lacrimal gland. MIF protein elevation was confirmed via western blot analysis, and the spatial similarity of MIF and VEGF expression in the cornea was noted during the wound healing process. 8-0 polyglactin sutures soaked in MIF induced significantly higher numbers of new vessels on the mouse cornea after 7 days (p=0.003, Mann-Whitney test). CONCLUSIONS These findings indicate that MIF performs a crucial role in wound healing on the ocular surface after the induction of chemical burns.