Abstract
Purpose: :
Any delay in the healing of corneal lesions is a major clinical concern. We have recently reported that bovine lactoferrin (BLF) accelerates epithelial wound closure however the molecular region with this activity has yet to be located. This study identified the BLF lobe with the strongest promotion of corneal epithelial healing.
Methods: :
BLF was cleaved by limited tryptic hydrolysis into its constituent lobes that were then purified by ion exchange and size exclusion chromatography. The purity and identity of the lobes were confirmed by SDS-PAGE and N-terminal sequencing, respectively. These were tested in vitro, using an alkali-burn to confluent layers of human corneolimbal epithelial cells, and in vivo, in guinea pig models of debridement (n=36) and alkali-burn (n=36) corneal epithelial injury. Alkali-burns were created by application of a filter paper disc impregnated with sodium hydroxide. With debridement wounds the area was demarcated by trephine for full thickness epithelial removal by gill knife. Native-BLF, N-lobe, C-lobe, or vehicle was applied 8x over 24 h and 3x daily thereafter. Closure was monitored by imaging of the fluorescein stained lesions.
Results: :
In vitro. The C-lobe (6.4 µM to 128 µM) promoted greater wound healing than native-BLF (p<0.05) or N-lobe (p<0.001). The reduction in wound area at 24 h peaked at 3.5 and 2.5 fold for the C-lobe and native-BLF, respectively, relative to the BSA control. In vivo. BLF C-lobe accelerated healing of debrided corneal epithelia. Wounds treated with C-lobe were smaller than those treated with the N-lobe (p=0.007) or vehicle (p<0.001) by 18 h and smaller than the native-BLF (p=0.016) group by 24 h. Complete closure was observed in 67% of C-lobe, 22% BLF and 0% vehicle by 24 h. With the alkali-burn model, native-BLF (p=0.005) and C-lobe (p=0.013) healed wounds faster than the vehicle but did not differ significantly from each other.
Conclusions: :
The C-lobe of BLF promotes corneal epithelial wound healing and appears to be more effective than native-BLF in wounds characterised by minimal inflammation. BLF C-lobe may be a novel therapeutic for the treatment of corneal lesions.
Keywords: wound healing • cornea: epithelium • protein structure/function