Recombinant Human MG53 Protein Protects Against Alkaline-Induced Corneal Injuries in Mice

Abstract

Introduction: The current study was designed to test the potential role of recombinant human MG53 (rhMG53) protein on protecting against alkaline-induced corneal injury in mice.

Materials and methods: A round filter paper with 2-mm diameter was soaked in 1 mol/L of NaOH solution. The mouse alkaline injury was generated by placing the filter paper directly on the cornea for 30 seconds and washed with 30-mL saline; 10 µL of rhMG53 solution (20 µg/mL) or saline control was topically administrated on the mouse corneas (twice per day for 10 days). Re-epithelialization was measured by fluorescein staining and imaged by a slit lamp equipped with a digital camera. Clinical neovascularization and opacity scores were measured every day after injury. Ten days after injury, mice were sacrificed and corneas were dissected out for flat mount staining of CD31 for neovascularization.

Results: MG53 was present in both dog aqueous humor and human tears. mg53-/- corneas were more susceptible to alkaline-induced corneal injury. Topical treatment of rhMG53 improved re-epithelialization, suppressed neovascularization, and fibrosis induced by alkaline injury.

Conclusions: rhMG53 may be an effective means to treat corneal wounding.

FIGURE 1.

MG53 is present in aqueous humor and tears; genetic ablation of MG53 leads to compromised corneal wound healing. (A) MG53 is a member of TRIM family proteins with RING, B-box, Coiled-coil, and SPRY domains. Endogenous MG53 can be detected in canine aqueous humor (B) and human tear (pointed by the arrow) (C) samples. Bands above 55 kDa in (C) are nonspecific protein recognized by the antibody. (D) After alkaline-induced corneal injury, mg53-/- cornea developed higher level of opacity and vascular invasion as compared to those in wild-type cornea.

FIGURE 2.

rhMG53 treatment promotes re-epithelialization and suppresses fibrosis and neovascularization after corneal wound in wild-type mice. (A) Representative images of fluorescein staining of corneas at indicated time points (upper panels) and quantification of fluorescein intensity by ImageJ software. (B) Representative macro photos of injured corneas at indicated time points (upper panels) and opacity scores (lower panel). (C) Flat mount confocal images of CD31 signal in injured corneas from saline control group and rhMG53-treated group (upper panels). Clinical opacity scores after alkaline injury were summarized (lower panel). (n = 6 per group. *P < 0.05; **P < 0.01).