Therapeutic effects of mucosal tolerance on experimental colitis in rats.

Abstract

OBJECTIVE: To analyze the therapeutic effect of oral tolerance and nasal tolerance singly and in combination with mucosal adjuvant on experimental colitis in rats. METHODS: Rat models were established using trinitrobenzenesulphonic acid enemas. Ovalbumin was used as inducing antigen and lipopolysaccharide as adjuvant. Colonic scores, splenic mononuclear cell proliferation, and expressions of Toll-like receptors (TLR) and regulatory T cells were determined. RESULTS: Colonic scores decreased most significantly after ovalbumin and lipopolysaccharide nasal administration (P<0.05). Colonic expression of forkhead box P3 in rats after ovalbumin and lipopolysaccharide oral (P<0.05) and nasal administration (P<0.01) were both significantly higher than untreated rats. TLR2 expression on CD4(+)CD25(+) T cells decreased most significantly after ovalbumin and lipopolysaccharide nasal therapies (P<0.01). TLR4 colonic expression decreased significantly after ovalbumin and lipopolysaccharide oral administration (P<0.05) and lipopolysaccharide oral administration (P<0.05). CONCLUSION: Although experimental colitis prevented oral tolerance, nasal tolerance was successfully induced. The therapeutic effect of nasal tolerance combined with adjuvant produced the best results. TLR downregulation and CD4(+)CD25(+) T cells upregulation were involved in mucosal tolerance.