Therapeutic effects of TNF-α binding peptide and TNFR blocking peptide on TNBS-induced colitis in rats

Objective To examine the therapeutic effects of TNF-α binding peptide (TBP) and TNFR blocking peptide (TRBP) on TNBS-induced colitis in rats. Methods The combination of TBP and TRBP (2.5 mg/kg, once a day) were administered orally to treat the rats with TNBS-induced colitis, while the control animals simultaneously were treated with sodium saline or irrelevant peptide. The macroscopic score and histological score of colonic damage were assessed; the myeloperoxidase (MPO) activity and nitric oxide (NO) production in serum and the colonic tissue were determined; the mRNA expressions of proinflammatory cytokines, such as IL-1β and IL-8, in the peritoneal macrophages were assayed by RT-PCR; protein expression of TNF-α in the colonic tissue was also investigated by SP immunohistochemistry assay. Results Macroscopic score, histological score, MPO activity, and NO production in rats treated with the combination of TBP and TRBP were significantly lower than those in groups of irrelavant peptide and sodium saline (P0.01). The protein expression of TNF-α and the mRNA expressions of IL-1β and IL-8 in rats treated with the combination of TBP and TRBP were also down-regulated (P0.01), compared with that in rats treated with the irrelevant peptide or sodium saline; the number of TNF-α positive cells in peptide-treatment group was larger than that in the two control group too (P0.01). Conclusion TNF-α binding peptide and TNFR blocking peptide obviously improve the symptoms of the TNBS-induced colitis in rats and alleviate the colonic pathological damage. This research will provide an experimental basis for the clinical treatment of the inflammatory disease.