Exogenous administration of hydrogen sulfide alleviates homocysteine induced inflammation in ARPE-19 cells

Abstract

Plasma homocysteine (Hcy) is an independent risk factor for Age related macular degeneration (AMD) and an inducer of inflammation. Homocysteine catabolism releases hydrogen sulfide (H₂S). H₂S has controversial effects on inflammation. In this study we have analysed the endogenous and exogenous H₂S in modulating inflammation using adult retinal pigment epithelial (ARPE-19) cells as an in vitro model for AMD. ARPE-19 cells were treated with various concentrations of Hcy (15, 30 and 50 μM) for 3 h. Expression of Hcy transulfuration genes (CBS, CSE) by qPCR and western blot. H₂S levels were measured using Free Radical Analyzer System (WPI, USA). The inflammatory markers (IL-6 and IL-8) were evaluated using real-time PCR and ELISA. Hcy exposure increased CBS protein expression, hydrogen sulfide levels and pro-inflammatory cytokines, modulating CBS by silencing did not alter H₂S levels, but inhibition of CSE with PAG inhibited H₂S production and decreased cytokine (IL-6 and IL-8) levels. On the contrary exogenous supply of hydrogen sulfide with NaHS and by compound 1c showed anti-inflammatory effects even in the presence of Hcy. This study shows that exogenous delivery of H₂S decreases inflammation in retinal pigment epithelial cells on exposure to Hcy in ARPE-19 cells.

Keywords: AMD; CBS; CSE; H(2)S; Inflammation.