Aquaporin 5 Induction to Treat Corneal Defects

Article: New study suggests that aquaporin could be key to repairing corneal defects
Source: Elsevier
Published: September 29, 2021

Loss of AQP5 inhibits corneal reepithelialization (top), NGF
promotes corneal epithelial wound healing and nerve regeneration
in AQP5-/- mice (middle), Akt inhibitor reverses corneal epithelial
wound healing and nerve regeneration in AQP5-/- mice (bottom)

A new study provides evidence that aquaporins play an important role in corneal cell proliferation and nerve regeneration. Aquaporins, or water channels, are transmembrane proteins that facilitate the transport of water (and small solutes), thereby maintaining cell water homeostasis. There are 13 types of aquaporins found in mammals. The study explored induction of aquaporin 5 (AQP5), which is expressed in the cornea, as a potential therapy to accelerate the resurfacing of corneal defects. In previous studies, the researchers found that deficiencies in AQP5 and nerve growth factor (NGF) resulted in delayed repair of corneal epithelial injury in mice. The present study sought to examine the mechanism of AQP5. The investigators engineered 189 male Aqp5 knockout (Aqp5-/-) mice and compared them to 75 normal (Aqp5+/+) male mice after their epithelial cells had been debrided. Corneal epithelial and nerve regeneration rates were significantly delayed in the Aqp5-/- mice, but were significantly increased in Aqp5-/- mice treated with NGF. NGF also improved the recovery of corneal nerve fiber density and sensitivity, and accompanied recovered levels of phosphorylated Akt in the Aqp5-/- mice. Unsurprisingly, when an Akt inhibitor was administered with the NGF, this led to reversal of Akt reactivation and corneal epithelial and nerve regeneration. The lead investigator comments, “It is exciting to find that Aqp5 deficiency can affect the nerve regeneration of mice by affecting the activation of NGF and Akt signaling pathways, which is not found in previous studies. These results need to be confirmed in a clinical setting, but they provide evidence for the involvement of aquaporins in cell proliferation and nerve regeneration and suggest AQP5 induction as a possible therapy to accelerate the resurfacing of corneal defects.”

My rating of this study: ⭐⭐⭐

Liu Y, Di G, Wang Y, et al. "Aquaporin 5 Facilitates Corneal Epithelial Wound Healing and Nerve Regeneration by Reactivating Akt Signaling Pathway." American Journal of Pathology.  11 August 2021. https://doi.org/10.1016/j.ajpath.2021.07.010