Feeding administration of daikenchuto suppresses colitis induced by naive CD4⁺ T cell transfer into SCID mice

Background and Aims Daikenchuto, a traditional Japanese herbal medicine, suppresses bacterial translocation by improvement of gastrointestinal motility and blood flow. As Daikenchuto reportedly reduces gastrointestinal inflammatory activity by these mechanisms, we analyzed whether Daikenchuto suppresses experimental colitis and reduces inflammatory cytokine expression in a mouse model. Methods Colitis was induced by transfer of naive CD4⁺ T cells of BALB/c mice into SCID mice, and mice were given either control or 2.7 % Daikenchuto-containing feed. We investigated body weight, clinical symptoms, histological changes, and Th1- and Th17-cytokine expression. Cytokine mRNA expression was analyzed using real-time RT-PCR. The ratio of IL-17+ and IFN-c+ CD4⁺ T cells were analyzed by flow cytometry. Results Daikenchuto delayed the development of colitis and significantly reduced the histological inflammation scores. Analyses of cytokine mRNA revealed that Th17 cytokines were significantly decreased in colons of mice that received Daikenchuto. Absolute numbers of IL-17+ or IFN-c+ CD4⁺ T cells per colon were less in mice receiving Daikenchuto than in mice that received control feed, as both groups received naive CD4⁺ T cells to induce colitis. Conclusions We demonstrated that feeding administration of Daikenchuto suppresses colitis induced by naive CD4⁺ T cell transfer into SCID mice. Daikenchuto may show clinical benefit in the treatment of human inflammatory bowel disease and further studies are warranted.