Strategies to manipulate the intestinal microbiota have been considered to promote immune health. The aim of the present study was to examine whether fructo-oligosaccharide, a typical prebiotic, could suppress antigen-specific skin inflammation by favourably changing the population of intestinal microbiota. Female BALB/c mice were fed a synthetic diet with or without fructo-oligosaccharide supplementation for 3 weeks and were then epicutaneously immunised with 2,4-dinitrofluorobenzene. Afterwards, mice continued to receive their respective diets. At 5 d after immunisation, the mice were ear challenged with the hapten. Ear swelling after the challenge was significantly reduced in the mice fed the diet supplemented with fructo-oligosaccharide than in mice fed the control diet. To characterise the change in the intestinal microbiota, DNA samples isolated from fresh faeces were subjected to PCR -denaturing gradient gel electrophoresis and real-time PCR based on 16S rDNA gene sequences. Dietary fructo-oligosaccharide altered the composition of intestinal microbiota. The numbers of bifidobacteria, but not lactobacilli, were significantly higher in mice fed the fructo-oligosaccharide-supplemented diet than in mice fed the control diet. Ear swelling was negatively correlated with the numbers of bifidobacteria in the faeces. Sequence analysis revealed that Bifidobacterium pseudolongum was the most predominant bifidobacteria in the intestine of mice fed the fructo-oligosaccharide-supplemented diet. These results suggest that consumption of fructo-oligosaccharide reduces contact hypersensitivity, which is associated with proliferation of B. pseudolongum in the intestinal tract of mice. Prebiotics: Intestinal microbiota: Contact hypersensitivity: MiceAllergic contact dermatitis is one of the most prevalent human skin diseases, causing moderate to severe inflammatory damage. This pathological condition arises after contact hypersensitivity (CHS) (1) . CHS is a T cell-mediated, antigenspecific type of skin inflammation that is induced by topical skin contact with haptens in a previously sensitised host (2,3) . When the host is sensitised by application of the hapten, skin dendritic cells capture the hapten and migrate to draining lymph nodes, where they prime specific T cells. These cells differentiate into CHS effector cells, which recirculate through the blood. The second contact with the same hapten leads to a skin inflammatory response that peaks 24-48 h after challenge. Avoidance of causal allergens is one of the emphasised therapeutic suggestions for CHS; however, avoidance is not practical in the majority of cases.2,4-Dinitrofluorobenzene (DNFB) (4) , picryl chloride (5) and oxazolone (6) have been used as typical haptens, which induce CHS in animals. DNFB-induced CHS in mice is the most widely used animal model for allergic contact dermatitis. In this model, mice are sensitised by application of DNFB onto shaved skin and are ear challenged by application of DNFB. Maximal ear swelling is observed 24 -48 h after challen...

We investigated whether feeding a purified compared with nonpurified diet supplemented with or without fructo-oligosaccharide (FOS; 50 g/kg diet) altered the response of C57BL/6 mice to DSS-induced diarrhea. In Expt. 1, we examined disease severity in mice receiving DSS (2% in drinking water) for 5 d. In Expt. 2, we measured cecal organic acid concentrations and fecal water-holding capacity (WHC). In Expts. 3 and 4, we tested whether polycarbophil calcium (PC), a water-absorbing polymer, altered fecal WHC and disease severity. FOS exacerbated diarrhea and weight loss in mice fed the purified diet and reduced fecal bleeding in mice fed the nonpurified diet (P < 0.05). Without DSS administration, cecal acetate and butyrate concentrations were higher in mice fed the nonpurified diet than in mice fed the purified diet (P < 0.05). Fecal WHC was higher in mice fed the nonpurified diet than in mice fed the purified diet (P < 0.05). One day after starting DSS administration, cecal succinate concentrations were higher in mice fed the FOS-supplemented purified diet than in mice fed the other 3 diets, whereas SCFA concentrations were higher in mice fed the nonpurified diet than in mice fed the purified diet (P < 0.05). PC supplementation increased fecal WHC and prevented FOS exacerbation of diarrhea in mice fed the purified diet (P < 0.05). We conclude that the effects of FOS on DSS-induced diarrhea differ in mice fed the purified and nonpurified diets. The protective effect of nonpurified diet was associated with increased production of organic acids and WHC in the intestinal contents.

Strategies to manipulate the gut microbiota have been explored for preventing allergy development. We previously showed that dietary supplementation with fructo-oligosaccharide (FOS) reduced 2, 4-dinitrofluorobenzene (DNFB)-induced contact hypersensitivity (CHS) in BALB/c mice. Because the CHS response was negatively correlated with the number of faecal bifidobacteria, particularly Bifidobacterium pseudolongum, the present study aimed to examine whether oral administration of B. pseudolongum affects CHS response. Viable B. pseudolongum was successfully isolated from mouse faeces. Female BALB/c mice were fed a synthetic diet with or without FOS supplementation, and B. pseudolongum (2 £ 10 7 cells) was administered daily throughout the experimental period. Two weeks after starting the test diets, mice received DNFB on the ear auricle twice at 7-d intervals. Conventional cultivation and molecular biological analyses based on 16S rRNA gene sequences showed that administration of FOS and B. pseudolongum resulted in higher excretion of viable bifidobacteria, mainly B. pseudolongum. Although dietary FOS reduced the CHS response as demonstrated by ear swelling, B. pseudolongum administration resulted in a reduction in the initial phase only of the CHS response. B. pseudolongum administration increased hapten-specific IgG1, while dietary FOS decreased IgG2a in sera. Administration of FOS and B. pseudolongum decreased interferon-g production and increased IL-10 production in cervical lymph node cells restimulated with hapten in vitro. We conclude that B. pseudolongum proliferation in the intestinal tract is partially responsible for the reduction in DNFB-induced CHS response by dietary supplementation with FOS in mice, which may be mediated by the modulation of antigen-induced cytokine production. Prebiotics: Bifidobacteria: Contact hypersensitivity: MiceCommensal microbiota in the intestinal tract plays an important role in the normal development of the immune system (1,2) . Therefore, strategies for microbiota manipulation have been explored for the prevention of the onset of immune diseases such as allergy. This idea is supported by epidemiological data demonstrating that differences in the composition of gut microbiota in infancy precede the development of atopic dermatitis (3) . In addition, clinical trials showed that administration of probiotic bacterial strains, such as Lactobacillus rhamnosus GG, was beneficial in both the prevention (4,5) and treatment (6) of early allergic diseases. However, some studies reported that L. rhamnosus GG and Lactobacillus acidophilus did not have a preventative effect in infancy (7 -9) . Therefore, there is currently insufficient data to recommend probiotics as part of a standard therapy in the treatment or prevention of allergic conditions (10) .Prebiotics, such as indigestible oligosaccharides, have also been considered to promote immune health by selectively stimulating the growth and/or activity of beneficial bacteria, such as bifidobacteria and lactobacilli, in the intestinal...

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