Identification of duloxetine to treat aniridia‐related keratopathy: Link to inflammation?

Abstract

Haploinsufficiency of PAX6 in humans is the main cause of congenital aniridia, a rare eye disease characterized by iris hypoplasia and reduced visual acuity. Patients have also progressive disorders including aniridia‐related keratopathy (ARK), caused by a combination of factors including limbal stem‐cell deficiency, impaired healing response, abnormal differentiation, and infiltration of conjunctival cells onto the corneal surface. It usually begins in the first decade of life resulting in recurrent corneal erosions, sub‐epithelial fibrosis with corneal decompensation and opacification. Unfortunately, current treatment options for aniridia patients are currently limited. There is no in vitro cellular model of AKT needed for drug/therapeutic tools screening and validation. We used genome editing (CRISPR/Cas9) to introduce a nonsense mutation into one allele of the PAX6 gene in limbal stem cells.The mutated cells displayed reduced cell proliferation and cell migration but enhanced cell adhesion. Known PAX6 targets expression was also altered. Of interest, recombinant PAX6 protein was sufficient to rescue the phenotype. By High Throughput Screening of a FDA‐approved library, we identified Duloxetine, a selective serotonin and norepinephrine reuptake inhibitor antidepressant, that rescued both PAX6 endogenous protein level and altered cell migration of the mutant limbal stem cells, through specific inhibition of the ERK/MEK pathway. Furthermore, we found that Duloxetine modulates inflammation through activation of Pax6, strongly suggesting that Pax6 could be a modulator of neuroinflammation. Since Duloxetine is already used as anti‐psychotropic drugs, its repurposed use to treat topically aniridia eye and other ocular inflammatory diseases could become realistic.