Figure 1.
Prevention of 2, 4, 6-trinitrobenzene sulfonic acid (TNBS)-induced colitis in rats by P28GST treatment or established infection with living parasites. Sprague-Dawley rats were immunized with two injections of 25 μg kg−1 P28GST at 1-month interval or infected with living Schistosoma cercariae either 5 weeks (established infection) or 1 week (recent infection) before TNBS injection. TNBS colitis was induced in all the groups, except negative controls, which received ethanol solution. Positive control rats were only injected with TNBS. All rats were killed 4 days after injection of TNBS or ethanol, i.e., 39 days after the first injection or infection. (a) Clinical score of rats with TNBS-induced colitis or negative controls. (b) Histological score of colon tissues assessed blindly by a pathologist to determine the degree of colitis using a score from 0 to 6. (c) Myeloperoxidase (MPO) was evaluated in the colon in the five groups of rats by enzyme-linked immunosorbent assay. Results are expressed as ng per mg of total proteins. (d) Interleukin (IL)-1β, (e) tumor necrosis factor (TNF), and (f) IL-17 mRNA levels analyzed by quantitative PCR were significantly lower in the P28GST-treated rats than in the colitis control group or in the recent infection group. No significant difference was observed between P28GST-treated rats and rats with established infection. Results are expressed as means±s.e.m.; n=20 rats per group. *P<0.05; **P<0.01; NS, not significant.