Rhodanese, but not cystathionine-γ-lyase, is associated with dextran sulfate sodium-evoked colitis in mice: A sign of impaired colonic sulfide detoxification?

Clinical studies suggest that colonic luminal hydrogen sulfide (H2S), produced by sulfate-reducing bacteria or through other pathways, might be involved in the pathogenesis of inflammatory bowel disease (IBD). Nonetheless, this hypothesis has been poorly investigated by basic studies using laboratory animals. We thus focused on two enzymes, cystathionine-γ-lyase (CSE) that generates H2S from l-cysteine, and rhodanese that directly or indirectly detoxifies H2S, particularly in relation to the colitis induced by dextran sulfate sodium (DSS) in mice. CSE was a major H2S-forming enzyme in colonic and renal homogenates from mice and rats, and the rhodanese activity was also detectable in both tissues. Colitis-related symptoms including decreased body weight gain, diarrhea, hematochezia and shortening of colon length were observed in the mice drinking DSS. Those symptoms were not or only slightly attenuated by repeated administration of a CSE inhibitor. CSE activity and protein levels in the colonic tissue did not notably change in the mice with colitis. In contrast, the activity and protein/mRNA levels of rhodanese in the colon, but not kidney, significantly decreased nearly in parallel with the development of colitis, followed by elevation of rhodanese activity in red blood cells (RBCs). These data show that rhodanese, but not CSE, is associated with DSS-induced colitis in mice, leading to a hypothesis that impaired detoxification of H2S due to down-regulation or suppression of colonic rhodanese is involved in IBD. The delayed enhancement of rhodanese activity in RBCs, a possible compensative event, might be available as a disease marker for IBD.