Effect of connexin 43 inhibition by the mimetic peptide Gap27 on corneal wound healing, inflammation and neovascularization

Abstract

Background and PurposeThe connexin 43 (Cx43) mimetic peptide Gap27 was designed to transiently block the function of this gap junction. This study was undertaken to investigate the effect of Gap27 on corneal healing, inflammation and neovascularization.Experimental ApproachThe effect of Gap27 on wound healing, inflammation and vascularization was assessed in primary human corneal epithelial cells (HCEC) in vitro and whole human corneas ex vivo, and in an in vivo rat wound healing model.Key ResultsGap27 enhanced the wound closure of HCEC in vitro and accelerated wound closure and stratification of epithelium in human corneas ex vivo, but did not suppress the corneal release of inflammatory mediators IL‐6 or TNF‐α in vivo. In human corneas ex vivo, F4/80 positive macrophages were observed around the wound site. In vivo, topical Gap27 treatment enhanced the speed and density of early granulocyte infiltration into rat corneas. After 7 days, the expressions of TNF‐α and TGFβ1 were elevated and correlated with inflammatory cell accumulation in the tissue. Additionally, Gap27 did not suppress VEGF release in organotypic culture, nor did it suppress early or late VEGFA expression or neovascularization in vivo.Conclusions and ImplicationsGap27 can be effective in promoting the healing of superficial epithelial wounds, but in deep stromal wounds it has the potential to promote inflammatory cell migration and accumulation in the tissue and does not suppress the subsequent neovascularization response. These results support the proposal that Gap27 acts as a healing agent in the transient, early stages of corneal epithelial wounding.

Advanced Glycation End Products and Receptor (RAGE) Promote Wound Healing of Human Corneal Epithelial Cells

“…Nevertheless, and specifically concerning the action of Cx43 in wound healing, it could remain controversial because previous publications show either a positive or a negative action of intercellular gap junction proteins in the wound healing process (a variation that could also reflect differences in the cell types examined). [39][40][41][42][43][44][45][46][47][48][49][50]61 Despite all this, our data clearly indicate that the "RAGE-Cx43" couple is alarmin-dependent and associated with a positive action for the initial steps of healing of an acute injury to the corneal epithelium.…”

“…Cx43 is a well-known target gene of the RAGE pathway, and its expression is described as being modulated during wound healing. [39][40][41][42][43][44][45][46][47][48][49][50][51] We first checked and confirmed the basal expression of the Cx43 protein in the human cornea epithelium and in the HCE cell model (Fig. 4A).…”

Connexin 43: Key roles in the skin

“…Downregulation of Cx43 following tissue injury significantly reduces ECM deposition, inflammation response and scar formation, and accelerates wound healing rates. Currently, Cx43 expression levels and functions have been presented in skin injury, skeletal muscle regeneration (82), ischemia/reperfusion injury (83) and cornea repair (84). The Cx-associated compounds are in development and indicate promising therapeutic opportunities in preclinical evaluation (85).…”

Characterization and Regulation of Gap Junctions in Porcine Ciliary Epithelium

“…35 No adverse complications in the cornea and surrounding tissues resulted from down-regulation of Cx43 in rats. 36 In contrast, inhibition of Cx43 was reported to aid corneal wound healing in humans both in vitro 37 and in vivo. 38 Cataract formation did not occur in the crystalline lens of Cx43 knockout mice.…”