P049 H2S confers colonoprotection against TNBS-induced colitis by HO-1 upregulation in rats
K. Kupai*, M. Veszelka, S. Török, Z. Szalai, A. Pósa, C. Varga
University of Szeged, Faculty of Science and Informatics, Department of Physiology, Anatomy and Neuroscience, Szeged, Hungary
Hydrogen sulfide (H2S) is an endogenous mediator that relaxes vascular smooth muscle, exhibits several antiinflammatory activities and contributes to protection
Specially, we investigated the beneficial effects of H2S and whether heme-oxygenases (HO) are involved in the H2S-induced colonal cytoprotection against 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis in rats. Male Wistar rats were treated with TNBS (10 mg) to induce colitis. H2S donor (Lawesson's reagent) were used at different concentrations (60; 30; 15; 7.5; 3.75; 1.87; 0.93 µM; dissolved in carboxymethylcellulose) twice daily per os (from 0 day to 3. day). 72 h after TNBS treatment colon samples were collected to measure the extent of inflammation, myeloperoxidase (MPO), and HO activities and TNF-alpha content. In a separate experiment, HO activity was inhibited by tin protoporphyrin (SnPP, 30 µmol/kg/day, s.c ) on the day of TNBS challenge (10 mg)in co-treatment with H2S donor (2 x 1.87µM, per os).
Twice-daily treatment with H2S donors significantly decreased the extent of colonal inflammation in a dose dependent manner compared to vehicle-treatment. The most effective concentration was 3.75 µM daily dose of H2S donor against inflammation (27.4 ± 1.5 vs. 46.2 ± 4.3; %). Per os administration of H2S donor reduced TNBS-provoked MPO activity (19.07 ± 3.6 vs. 36.67 ± 2.95; mU/mg/protein), TNF-alpha levels (89.95 ± 9.43 vs. 531.67 ± 32; pg/mg protein),while increasing colonic HO enzyme activity (0.98 ± 0.05 vs. 0.82 ± 0.6 nmol bilirubin/h/mg protein). The protective effect of H2S was abolished by co-treatment with an inhibitor of HO activity (TNBS:35.6 ± 2.4; TNBS+H2S: 21.6 ± 5.6; TNBS+H2S+SnPP: 28.8 ± 2.6 % extent of lesion) (from 60,6 ± 15,7 to 80,89 ± 7,3 % of the extension of TNBS lesion).
Our findings suggest that H2S confers protection dose dependently, probably by modulation of anti-inflammatory parameters and HO enzyme activity.