Hydrogen sulfide exposure induces inflammatory responses in rabbit cornea in vivo

Abstract

Purpose : Hydrogen sulfide (H₂S) is a toxic gas and a chemical warfare agent. Exposure to H₂S leads to vision impairment. However, limited in vivo data exists to reveal H₂S-induced corneal toxicity. Here we present clinical, histological, and molecular characteristics of rabbit corneas exposed to H₂S in vivo.

Methods : The study was approved by the institutional animal care and use committee and followed ARVO guidelines. New Zealand White rabbits were exposed to H₂S 100ppm for 15 minutes. Clinical eye manifestations in live rabbits were assessed with the slit-lamp microscope, spectralis, confocal HRT3 microscope, specular microscope, fluorescein staining, pachymetry, and applanation tonometry immediately after H₂S exposure, day 3, and 7. Post euthanasia, corneas were subjected to histological, molecular, and cellular analyses.

Results : H₂S-exposed rabbit eyes showed keratoconjunctivitis and eyelid edema post-exposure and these symptoms were gradually resolved by day 7. Fluorescein staining revealed epithelial damage in H₂S-exposed corneas at 0 h post-injury and the epithelium was healed completely by day 7 post-injury. Confocal HRT3 microscopic examination revealed severely damaged anterior stroma (cell debris), moderately damaged mid stroma, mild damaged posterior stroma, and no endothelial damage at 0 h post-injury. At day 7 post-injury, no recovery was noted at the anterior stroma. However, the mid and posterior stroma showed minimal damage (increased cell density). H₂S-exposed corneas showed no endothelial cell loss in specular microscopic examination. H₂S-exposed eyes showed slightly increased central corneal thickness and intraocular pressure. However, these differences were statistically not significant (p > 0.05). Further clinical, histological and molecular studies are underway.

Conclusions : Ocular H₂S exposure caused keratoconjunctivitis, corneal and eyelid edema, and damage to corneal stroma in rabbits in vivo. Ongoing studies will provide additional clinical and mechanistic information.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.