Corneal phenotype of a Slc4a11 knockout murine model for congenital hereditary endothelial dystrophy

Abstract

Purpose : Mutations in the SLC4A11 protein affect the cornea in three conditions: Congenital hereditary endothelial dystrophy (CHED), Harboyan syndrome, and late-onset Fuchs corneal endothelial dystrophy. CHED is characterized by blindness at birth or in early infancy resulting from bilateral corneal opacification. A Slc4a11 knockout (KO) mouse, generated by gene deletion (Han et al. 2013) was acquired (Singapore Eye Research Institute; Singapore) in order to study this disease. The goal of this study was to confirm the phenotype of this Slc4a11 KO mouse model as a function of age, using the wild type (WT) mouse as a control.

Methods : Genotyping was performed by PCR (REDExtract-N-AmpTM Tissue PCR Kit, Sigma-Aldrich). Slc4a11 WT and KO mice aged from 5 to 50 weeks were studied (n = 5 animals per age group; 5-week age intervals). Slit lamp examination, anterior segment-ocular coherence tomography (OCT930SR; Thorlabs), corneal endothelial cell staining, and scanning (SEM) and transmission (TEM) electron microscopy were used to assess the morphological and cellular differences between the two groups. Expression of the basolateral membrane transporter NaBC1 within the corneal endothelium was also assessed using immunohistochemistry.

Results : Diffuse and progressive corneal opacification was observed at the slit lamp in the Slc4a11 KO mice, whereas WT corneas remained clear over the entire study period (overall transparency score: p < 0.0005). Central corneal thickness increased as a function of age for KO (mean increase 1.47 ± 1.01 µm/week; p = 0.01) as well as for WT (0.29 ± 0.16 µm/week; p = 0.001) groups, with a significant difference in slope between groups (p = 0.03). Early TEM results showed vacuole degeneration of the corneal endothelium in the 15-week KO mouse, while no endothelial vacuolar degeneration was observed in the WT corneas.

Conclusions : The corneal phenotype of this Slc4a11 KO mouse is representative of the clinical manifestations of CHED in human subjects, confirming the usefulness of this model for studying pathophysiology and therapeutic alternatives for Slc4a11-associated corneal dystrophies.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.