Abstract
Purpose :
To test the effects of airborne particulate with a diameter of <10 μm (PM10) on loss of barrier integrity in immortalized human corneal epithelial cells (HCET) and whether SKQ1 is restorative.
Methods :
HCET were exposed to 100 μg/ml PM10 and incubated for 24h. To test the effects of SKQ1, a subset of cells were pre-treated with 50 nM SKQ1 for 1 hour before PM10 exposure. Electric Cell-Substrate Impedance Sensing (ECIS) technology was used to monitor the impact of PM10 on HCET cell behavior in real-time by measuring the resistance (R), which served as an indicator for cell barrier strength. RT-PCR and western blotting tested the mRNA and protein levels of tight junction proteins: zonula occludens (ZO)-1, 2, occludin and claudin-1. mRNA and protein levels of adhesion molecules N-cadherin, E-cadherin, wnt5a and β-catenin were similarly tested. Additionally, levels of mucins MUC1, MUC 4 and MUC16 were also tested.
Results :
In HCET, PM10 exposure significantly reduced mRNA levels of ZO-1, occludin, claudin-1, MUC1, MUC4 and MUC16 compared to control. Additionally, PM10 exposure significantly decreased mRNA levels of adhesion molecules E-cadherin and β-catenin but increased N-cadherin and wnt5a levels compared to control. SKQ1 pre-treatment significantly reversed these effects. PM10 exposure also significantly lowered protein levels of ZO-1, E-cadherin and occludin by about 50%. SKQ1 restored levels of ZO-1 by approximately 20%, E-cadherin by 25% and occludin by 35%. ECIS data showed that compared to control, cells exposed to PM10 exhibited a significant reduction in barrier strength throughout the course of the experimental indicated by a reduced resistance (R) at 4,000 Hz.
Conclusions :
PM10 exposure reduces the levels of tight junction, adhesion and mucin proteins and compromises the seal between cells in the corneal epithelium, leading to a decrease in barrier strength. This effect was reversed by SKQ1.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.