Protective Action of Hydrogen Sulfide-Releasing Compounds against Oxidative Stress-Induced Cataract Formation in Cultured Bovine Lenses

Abstract

Purpose: The gaseous signalling molecule, hydrogen sulfide (H₂S) has antioxidant, anti-inflammatory and anti-apoptotic properties. Since oxidative stress has been implicated in the pathogenesis of cataracts and lenticular hydrogen peroxide (H₂O₂) is elevated in some cataract patients, the present study investigated the ability of H₂S-releasing compounds to prevent H₂O₂-induced cataract formation in cultured bovine lenses.

Methods: Lenses were cultured in either Dulbecco's Modified Eagle Medium (DMEM; control); H₂O₂ (50 mM); ascorbic acid (AA; 3 mM) (positive control); and the H₂S-releasing compounds (diallyl trisulfide [DATS] or GYY4137) in the presence of H₂O₂ (50 mM). Lens opacity was determined using a plate reader to measure transmittance. Lens glutathione content (GSH), superoxide dismutase (SOD) activity and lactate dehydrogenase (LDH) cytotoxicity were assessed before and after treatment with the H₂S-releasing compounds.

Results: Both DATS (10^-7M - 10^-4M) and GYY4137 (10^-7M - 10^-4M) significantly (p < .001) attenuated H₂O₂ (50 mM)-induced loss in transmittance, with DATS (10^-4M) and GYY4137 (10^-7M) achieving a maximal reversal of opacity by 56.86 ± 0.01% (n = 6) and 8.39 ± 0.11% (n = 6) after 120 hours, respectively. These observations were corroborated by photographic evaluation, where DATS (10^-5M - 10^-4M) and GYY4137 (10^-7M - 10^-5M)-treated lenses had relatively clear grids after 120 hours, compared to H₂O₂ (50 mM)-treated lenses. The H₂O₂ (50 mM)-induced decline in total GSH content and total SOD activity were significantly (p < .001; n = 5) reversed by DATS (10^-4M) and GYY4137 (10^-7M). After 24 hours, DATS (10^-4M) and GYY4137 (10^-7M) significantly (p < .001; n = 4) reduced cytotoxicity of primary bovine lens epithelial cells by 33.88 ± 4.59% and 36.19 ± 10.53%, respectively.

Conclusion: Both H₂S-releasing compounds protected cultured bovine lenses against oxidative stress-induced cataract formation. The slow-releasing H₂S compound, GYY4137 was more potent than DATS in restoring lenticular total GSH content and total SOD activity along with reducing H₂O₂ (50 mM)-induced cytotoxicity.

Keywords: Cataracts; antioxidants; hydrogen peroxide; hydrogen sulfide; lens opacity.