Abstract
Purpose :
Corneal tissue damage is often associated with exposure to arsenicals, which are highly toxic chemical warfare agents (CWAs), including lewisite (LEW). However, the difficulties associated with accessing the posterior ocular tissues in CWA-affected individuals and the technical challenges of using CWAs in laboratory settings make it necessary to use relatively less toxic arsenicals in eye research. Similar to LEW, phenylarsine oxide (PAO) activates a pro-inflammatory response, oxidative stress, and a cell death program in the lung, liver, and skin tissues. We hypothesized that arsenical exposure results in corneal injury and retinal tissue damage.
Methods :
Human corneal epithelial cells (HCEC), keratocytes (HCK), and retinal endothelial cells (HREC) were incubated with 200 nM PAO for 6, 12, and 24 h. Cytokine expression was detected using qRT-PCR. Direct ocular exposure of C57BL/6 mice to PAO was conducted at doses of 5 and 50 µg for 3 min using the patch method. Cytokine gene expression, retinal functional, and histological analyses of PAO-treated mice were performed 1 day and 14 days after exposure using qRT-PCR and ERG, respectively.
Results :
Treating human corneal and retinal cells with PAO resulted in a significant elevation of Il-1β (HREC 2.7-fold; HCEC 2-fold), Cox2 (HCK 3.7-fold; HREC 15.5-fold; HCEC 4.6-fold), and Ifn α (HCK 349.3-fold; HREC 11.5-fold; HCEC 33.7-fold). Similar to the in vitro results, the in vivo findings showed that there was a marked increase in cytokine gene expression in both the corneal and retinal tissues of exposed mice. Mice treated with 5 µg PAO per eye showed significant increases in Il-6 (cornea 13-fold; retina 106-fold), Il-1β (cornea 7-fold; retina 22-fold), and Cox2 (cornea 11-fold; retina 109-fold). Mice exposed to 50 µg PAO per eye showed a remarkable elevation of Il-6 (cornea 1,337-fold; retina 134-fold), Il-1β (cornea 1,213-fold; retina 2,705-fold), and Cox2 (cornea 82-fold; retina 80-fold) mRNA. In addition, PAO exposure resulted in diminished scotopic a- and b-wave ERG amplitudes at 2 weeks after exposure.
Conclusions :
These findings establish a foundation for future mechanistic ocular toxicity studies of arsenical exposed populations, demonstrating that not only the corneal tissue, but also the retina may be damaged depending on the severity of exposure.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.