Reactive oxygen species (ROS) are essential mediators in epidermal growth factor (EGF)-stimulated corneal epithelial cell proliferation, adhesion, migration, and wound healing

Abstract

EGF is an essential growth factor needed for epithelial cell proliferation and wound healing of the cornea, but the molecular mechanism is not understood. Although studies have shown that EGF in some non-phagocytic cells induces ROS generation, little is known about the role of ROS in corneal epithelial cells. Therefore, we examined the potential physiological role of ROS in corneal cell proliferation, adhesion and wound healing using rabbit or human corneal epithelial cells, and pig whole cornea organ culture as models. EGF (5 ng/ml)-induced ROS in serum-starved RCE or HCE cells were captured as DCFH fluorescence and detected by confocal microscopy. The elevation of ROS was eradicated when the cells were pretreated with an antioxidant N-acetylcysteine (NAC) or mannitol, or with inhibitor to NADPH oxidase (DPI), or to lipoxygenase (NDGA). EGF-induced ROS generation correlated with cell growth and activation of Akt and MAPK signaling pathways, while NAC eliminated all these effects. EGF-stimulated cell adhesion or migration in cell culture was greatly suppressed in the presence of NAC while EGF-facilitated epithelial cell wound healing in corneal organ culture was also blocked by NAC. This is the first demonstration of a novel ROS physiological function in corneal wound healing.