TNF and serum lipopolysaccharide activity: Likewise, the slow-releasing H2S donor GYY4137, can reduce LPS-induced endotoxemia in mice [25], as well as the synthesis of pro-inflammatory mediators (such as TNF-α, IL-1β, IL-6, NO and PGE2) by LPS-stimulated RAW 264.7 macrophages in vitro [26].