Characterization of hydrogen sulfide toxicity to human corneal stromal fibroblasts

Hydrogen sulfide gas (H₂ S) is a chemical weapon and a common environmental pollutant. H₂ S intoxication is lethal to humans and animals. H₂ S contact to the eye can cause vision loss. However, the molecular mechanisms associated with H₂ S toxicity to the cornea remain unclear, and no specific therapy exists to mitigate ocular damage from H₂ S. Here, we report H₂ S-induced cytotoxicity and the parameters contributing to the molecular mechanisms associated with corneal toxicity using primary human corneal stromal fibroblasts (hCSFs) in vitro. Sodium hydrosulfide (NaSH) was used as a source of H₂ S, and the cytotoxicity of H₂ S was determined by treating hCSF cells with varying concentrations of NaSH (0-10 mM) for 0-72 hours. Changes in cell proliferation, oxidative stress factors, and the expression of inflammatory and fibrotic genes were studied using standard commercial kits and qRT-PCR. NaSH exposure to hCSFs showed dose- and time-dependent cytotoxicity. The IC₅₀ of NaSH was determined to be 5.35 mM. NaSH 5.35 mM exposure led to significantly decreased cytochrome c oxidase activity, increased ROS production, and increased expression of inflammatory and fibrotic genes in hCSF cells. H₂ S/NaSH exposure alters normal mitochondrial function, oxidative stress, and inflammatory and fibrotic gene responses in corneal stromal fibroblasts in vitro.