TST and inflammatory bowel disease: Several clinical studies have suggested that colonic luminal hydrogen sulfide (H2S), with levels regulated by sulfate-reducing bacteria or colonic enzymes, such as H2S-producing enzymes, cystathionine γ-lyase (CTH; also known as CSE), and mercaptopyruvate sulfurtransferase (MPST; 3-MST), and H2S-degrating thiosulfate sulfurtransferase (TST; rhodanese) could be implicated in the IBD pathogenesis, especially UC [6,7].