Abstract
Purpose :
To investigate changes in mice corneal barrier function due to exposure to different concentrations of benzalkonium chloride (BAC) using a novel mouse corneal transepithelial electrical resistance (TER) assay.
Methods :
We succeeded in developing an innovative technique for corneal TER measurement in mice (Mohamed YH, et al. ARVO, 2023). In this innovative technique, we used the well tissue culture container and its insert to mount the mice globe and separates between the cornea and rest of globe to allow corneal TER measurements. In this study, ICR mice with large corneal diameters were used, and they were kept individually in cages free of wood debris for one week to prevent epithelial damage before the experiment. The explanted mice eyes were divided into groups and the corneal epithelium of these groups were exposed to different concentrations of BAC (0.1%, 0.2%, and 0.5%), in addition to control group. The corneal TER was measured after 1 and 3 minutes. Half of these eyes were fixed in glutaraldehyde and processed for transmission electron microscopic examination (TEM) and the other half in Formaldehyde and processed for Zo1 immunohistochemical evaluation (IHC).
Results :
The mean corneal TER for the mice used in this study was 482 ± 294 Ω cm2. After exposure to control, 0.1%, 0.2%, and 0.5% BAC (n=4), the TER was 100 ± 0%, 91 ± 14%, 83 ± 13%, and 34 ± 12% of the pre-exposure TER at 1 min, respectively with statistically significant decrease (P<0.001) with 0.5% BAC group. After 3 min, TER was 98±12%, 71±25%, 50±20%, 17±12% respectively with statistically significant decrease (P<0.01) with 0.2% BAC and 0.5% BAC (P<0.001) groups. TEM examinations showed decreased number of epithelial microvilli and loss of epithelial tight junctions between superficial cells in 0.2 % and 0.5 % BAC groups with shedding of some superficial cells. IHC examination showed decreased Zo1 staining of the corneal epithelium of the same groups as compared to control.
Conclusions :
Compared to rabbits and humans (in previous studies), in which 0.005% BAC reduced barrier function, higher concentrations of BAC are needed to reduce the barrier function in the mouse cornea. The results suggest that the mouse corneal epithelium may be more resistant to external stimuli.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.