Abstract
Purpose :
Evidence from literature demonstrates that exogenous administration of hydrogen sulfide (H2S) decreases inflammation in retinal pigment epithelial cells exposed to homocysteine (Ravi et al. 2021, EER 212:108759). Since lipopolysaccharide (LPS) has been reported to induce inflammation in cultured human iris-ciliary body (ICB) explants (Brito et al. 2004, EER 79:203), we investigated the pharmacological actions of H2S-releasing compounds on LPS-induced inflammation in cultured porcine ICB explants (using Tumor Necrosis Factor-alpha, TNFα, as a marker).
Methods :
Freshly isolated porcine ICB explants were cut into quadrants and cultured in Roswell Park Memorial Institute (RPMI) 1640 medium containing 1% penicillin-streptomycin. Explants were then exposed to different concentrations of LPS for 20 h. When used, H2S-releasing compounds, sodium hydrosulfide (NaHS) and GYY4137 were added to media 15 mins and 30 mins, respectively, before the end of the incubation period. Concentrations of TNFα in culture supernatants were measured using ELISA kit purchased from Sigma-Aldrich.
Results :
Different concentration of LPS tested elicited increases in TNFα production in cultured ICB explants over basal levels (7.21 ± 0.29 ng/g; n = 6). For instance, LPS 10 ng/ml, 25 ng/ml, and 50 ng/ml enhanced TNFα production up to 10.36 ± 0.23 ng/g (n = 6), 12.32 ± 0.40 ng/g (n = 5) and 11.80 ± 1.11 ng/g (n = 5), respectively. In the presence of LPS (25 ng/ml), a fast-releasing H2S compound, NaHS (5 µM and 50 µM) caused significant (p < 0.001) decreases in LPS-induced TNFα production by 22.7 % ± 3.6 % (n = 6) and 26.5 % ± 5.3 % (n = 5), respectively. Likewise, the slow-releasing H2S compound, GYY4137 (1 µM and 10 µM) evoked significant (p < 0.001) reductions of LPS-induced TNFα production by 25.0 % ± 3.7 % (n =5) and 19.9% ± 1.8 % (n = 4), respectively.
Conclusions :
We conclude that LPS can induce an inflammatory response in the cultured porcine ICB explants. Both fast- and slow-releasing H2S compounds reduced LPS-induced TNFα production in the ICB explants suggesting an anti-inflammatory action of this gas in the anterior uvea.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.