RESUMEN
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.
Asunto(s)
Colitis/inducido químicamente , Colitis/enzimología , Colon/metabolismo , Cistationina gamma-Liasa/metabolismo , Sulfato de Dextran/toxicidad , Sulfuros/metabolismo , Sulfuros/toxicidad , Tiosulfato Azufretransferasa/metabolismo , Anemia/sangre , Animales , Western Blotting , Colitis/patología , Colon/patología , Cistationina gamma-Liasa/sangre , Eritrocitos/efectos de los fármacos , Eritrocitos/enzimología , Sulfuro de Hidrógeno/metabolismo , Inactivación Metabólica , Masculino , Ratones , ARN/biosíntesis , ARN/genética , Ratas , Ratas Wistar , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Tiosulfato Azufretransferasa/sangre , Aumento de Peso/efectos de los fármacosRESUMEN
We investigated effect of hydrogen sulfide (H(2)S) on oxidative stress-caused cell death in gastric mucosal epithelial cells. In rat normal gastric epithelial RGM1 cells, NaHS, a H(2)S donor, at 1.5mM strongly suppressed hydrogen peroxide (H(2)O(2))-caused cell death, while it slightly augmented the H(2)O(2) toxicity at 0.5-1mM. The protective effect of NaHS was abolished by inhibitors of MEK or JNK, but not of p38 MAP kinase. NaHS at 1.5mM actually phosphorylated ERK and JNK in RGM1 cells. Glibenclamide, an ATP-sensitive K(+) (K(ATP)(+)) channel inhibitor, did not affect the protective effect of NaHS, although mRNAs for K(ATP)(+) channel subunits, Kir6.1 and SUR1, were detected in RGM1 cells. In anesthetized rats, oral administration of NaHS protected against gastric mucosal lesion caused by ischemia-reperfusion. These results suggest that NaHS/H(2)S may protect gastric mucosal epithelial cells against oxidative stress through stimulation of MAP kinase pathways, a therapeutic dose range being very narrow.