Clinical studies suggest that colonic
luminal hydrogen sulfide (H(2)S), 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-gamma-lyase (CSE) that generates H(2)S from
l-cysteine, and
rhodanese that directly or indirectly detoxifies H(2)S, particularly in relation to the
colitis induced by
dextran sulfate sodium (DSS) in mice. CSE was a major H(2)S-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 H(2)S 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.