Background Hydrogen sulfide (H2S) is an important signalling molecule that regulates many physiological (blood pressure) and pathophysiological (inflammation) processes in organs and cellular systems. Inorganic H2S donors like sodium hydrogen sulfide (NaHS) rapidly but uncontrollably release H2S leading to negative side effects (activation of MAPkinases etc.). Therefore, inducible H2S donors have recently emerged as useful tools for studying the molecular mechanism of H2S. In this study we report about the chemical and biological evaluation of a new class of organic H2S donors which release H2S only upon activation by thiols.
Materials and methods The H2S releasing compounds 5a, 8a and yz-5–093 were synthesised and kindly provided by M Xian´s group (Washington, USA). H2S release under physiological pH range (PBS, pH 7.4) was measured with a H2S-selective microelectrode. In intact cells, H2S production was monitored by the fluorescent probe WSP-1. To evaluate the anti-inflammatory potential of the H2S donors in vitro, mouse macrophages (RAW264 cell line) were incubated for 1 h with different concentrations (10–100 µM) of compounds 5a, 8a and yz-5–093 before the cells were stimulated for 24 h with LPS. IL-6 and TNF-α levels in cell culture supernatants were quantified by enzyme-linked immunosorbent assays (ELISAs).
Results All three compounds released H2S at similar concentrations. Cotreatment of RAW264 cells with compounds 5a, 8a and yz-5–093 downregulated LPS-induced IL-6 expression in a dose-dependent manner. TNF-α production was only affected at the highest concentration (100 µM).
Conclusion We demonstrate that thiol-inducible H2S donors represent a new scientific tool which allows to mimic the slow and continous H2S generation process in vivo. These donors might have therapeutic benefits in the treatment of chronic inflammatory disorders such as rheumatoid arthritis.