Cisd2 plays an essential role in corneal epithelial regeneration

Background: Age-related changes affecting the ocular surface cause vision loss in the elderly. Cisd2 deficiency drives premature aging in mice as well as resulting in various ocular surface abnormalities. Here we investigate the role of CISD2 in corneal health and disease. Methods: We studied the molecular mechanism underlying the ocular phenotypes brought about by Cisd2 deficiency using both Cisd2 knockout (KO) mice and a human corneal epithelial cell (HCEC) cell line carrying a CRISPR-mediated CISD2KO background. We also develop a potential therapeutic strategy that targets the Ca²⁺ signaling pathway, which has been found to be dysregulated in the corneal epithelium of subjects with ocular surface disease in order to extend the mechanistic findings into a translational application. Findings: Firstly, in patients with corneal epithelial disease, CISD2 is down-regulated in their corneal epithelial cells. Secondly, using mouse cornea, Cisd2 deficiency causes a cycle of chronic injury and persistent repair resulting in exhaustion of the limbal progenitor cells. Thirdly, in human corneal epithelial cells, CISD2 deficiency disrupts intracellular Ca²⁺ homeostasis, impairing mitochondrial function, thereby retarding corneal repair. Fourthly, cyclosporine A and EDTA facilitate corneal epithelial wound healing in Cisd2 knockout mice. Finally, cyclosporine A treatment restores corneal epithelial erosion in patients with dry eye disease, which affects the ocular surface. Interpretation: These findings reveal that Cisd2 plays an essential role in the cornea and that Ca²⁺ signaling pathways are potential targets for developing therapeutics of corneal epithelial diseases. Funding: This study was supported by the Ministry of Science and Technology (MOST) and Chang Gung Medical Research Foundation, Taiwan.