Polysulfides derived from the hydrogen sulfide and persulfide donor P* inhibit IL-1β-mediated inducible nitric oxide synthase signaling in ATDC5 cells: are CCAAT/enhancer-binding proteins β and 8 involved in the anti-inflammatory effects of hydrogen sulfide and polysulfides?

Hydrogen sulfide (H2S) emerged as an essential signaling molecule exerting beneficial effects in various car-diovascular, neurodegenerative, or musculoskeletal diseases with an inflammatory component, such as osteo-arthritis. These protective effects were initially attributed to protein S-sulfhydration, a posttranslational modification of reactive cysteine residues. However, recent studies suggest that polysulfides and not H2S are responsible for S-sulfhydration. To distinguish between H2S and polysulfide-mediated effects in this study, we used the slow-releasing H2S and persulfide donor P*, which can be decomposed into polysulfides. The effects of P* on IL-1 beta-induced inducible nitric oxide synthase (iNOS), a pro-inflammatory mediator in osteoarthritis, were determined by nitrite measurement, qPCR, and Western blotting in the murine chondrocyte-like cell line ATDC5. Decomposed P* significantly reduced IL-1 beta-induced iNOS signaling via polysulfides, independently of H2S. In line with this, the fast-releasing H2S donor NaHS was ineffective. In RAW 264.7 macrophages, similar results were obtained. P*-derived polysulfides further diminished IL-1 beta-induced CCAAT/enhancer-binding protein (C/ EBP) beta and 8 expression in ATDC5 cells, which might play a critical role in P*-mediated iNOS decline. In conclusion, our data support the view that polysulfides are essential signaling molecules as well as potential mediators of H2S signaling. Moreover, we propose that C/EBP beta/8 might be a novel target involved in H2S and polysulfide-mediated anti-inflammatory signaling.