AQP5 Regulates Corneal Nerve Distribution Through NETRIN-1 and SLIT3

Neurotrophic keratopathy (NK) is characterized by corneal nerve abnormalities. We investigated the role of aquaporin 5 (AQP5) in corneal nerve distribution and its regulation via the JUN-D-Ntn1/Slit3 signaling pathway.

Wild-type (Aqp5+/+) and Aqp5 knockout (Aqp5-/-) mice were used. Corneas were dissected, permeabilized, and immunolabeled with neuron-specific βIII-tubulin to visualize corneal nerves. Primary trigeminal ganglion neurons were isolated and cocultured with recombinant NETRIN-1 or SLIT3. Chromatin immunoprecipitation PCR assessed JUN-D binding to Ntn1 and Slit3 promoters. Corneal epithelial scraping was performed, followed by subconjunctival injection of the JUN-D activator or inhibitor to evaluate effects on nerve regeneration.

Whole-mount immunostaining revealed reduced corneal nerve density in Aqp5-/- mice. Corneal epithelial NETRIN-1 levels were decreased, whereas SLIT3 levels were increased in Aqp5-/- mice. NETRIN-1 promoted, and SLIT3 inhibited, neuronal axon growth. JUN-D inhibition upregulated Ntn1 and downregulated Slit3. Modulation of JUN-D influenced corneal epithelial healing and nerve regeneration following corneal epithelial scraping.

AQP5 deficiency disrupts corneal nerve architecture and may contribute to NK. AQP5 regulates corneal nerve distribution via the JUN-D-Ntn1/Slit3 pathway. These findings identify potential molecular targets for the prevention and treatment of NK.