Bovine Lactoferrin Promotes Corneal Wound Healing and Suppresses IL-1 Expression in Alkali Wounded Mouse Cornea

Abstract

Purpose: Using an in vitro cell culture model, bovine lactoferrin (BLF) stimulates healing of alkali-induced human corneal epithelial wounds. The present study examined the efficacy of BLF in promoting healing of corneal injury in vivo and explored BLF modulation of interleukin-1 (IL-1) during wound healing.Methods: Alkali injury was induced to BALB/c mice by exposure of the mouse cornea to a sodium hydroxide (NaOH)-soaked filter disc for 2 min. The corneal surface was irrigated after the injury with saline. Topical BLF in phosphate buffered saline (PBS) (10 µl, 62.5 μM), bovine serum albumin (BSA) (10 µl, 62.5 μM in PBS) or PBS only (10 µl) were applied three times daily to both the alkali-injured and uninjured eyes for 3 d. Wound healing was assessed using 0.1% fluorescein staining under slit lamp microscope. The corneas at 6 h, 24 h or 3 d post-injury and treatment were excised and examined histologically, homogenized corneal tissue was evaluated for expression of IL-1α and IL-1β.Results: After 6 h post-wounding and treatment no significant reduction of wound area was observed between treatments and infiltrating cells or IL-1 expression were not elevated in any group. By 24 h, BLF-treatment resulted in accelerated wound closure (100%) compared to PBS and BSA treatment (70% and 65%, respectively). BLF treatment reduced infiltrating cells compared to controls and no elevation of IL-1, whereas controls displayed elevated infiltrating cells and increased levels of IL-1. After 3 d, mice treated with BLF exhibited complete wound closure while control corneas still exhibited some minor defects. Resolution of inflammation with minimal remaining infiltrating cells was observed in all corneas by day 3, coincident to normal levels of IL-1α and IL-1β.Conclusion: BLF accelerated healing of corneal alkali injury in BALB/c mice which was associated with suppression of IL-1 and reduced infiltrating cells.