Activity-Dependent Neuroprotective Protein (ADNP)-Derived Peptide (NAP) Counteracts UV-B Radiation-Induced ROS Formation in Corneal Epithelium

The corneal epithelium, the outermost layer of the cornea, acts as a dynamic barrier preventing access to harmful agents into the intraocular space. It is subjected daily to different insults, and ultraviolet B (UV-B) irradiation represents one of the main causes of injury. In our previous study, we demonstrated the beneficial effects of pituitary adenylate cyclase-activating polypeptide (PACAP) against UV-B radiation damage in the human corneal endothelium. Some of its effects are mediated through the activation of the intracellular factor, known as the activity-dependent protein (ADNP). In the present paper, we have investigated the role of ADNP and the small peptide derived from ADNP, known as NAP, in the corneal epithelium. Here, we have demonstrated, for the first time, ADNP expression in human and rabbit corneal epithelium as well as its protective effect by treating the corneal epithelial cells exposed to UV-B radiations with NAP. Our results showed that NAP treatment prevents ROS formation by reducing UV-B-irradiation-induced apoptotic cell death and JNK signalling pathway activation. Further investigations are needed to deeply investigate the possible therapeutic use of NAP to counteract corneal UV-B damage.