Fig 1.
The start date of DSS administration was defined as day 0. C57BL/6J mice were randomized into 5 groups (n = 12/group), and each group was given sterile water and adaptation for 1 week. From day -7, each bacterial suspension or sterilized PBS treatment was started while free drinking of sterilized water was continued. From day 0, sterilized water was switched to DSS (1%) and colitis was induced. Weight measurement and fecal sample collection were carried out every week from day -7 to day 21, and further from day 0 to day 21; the assessment of inflammation and dissection of 3 animals per group were also performed.
Table 1.
DAI.
Fig 2.
Rate of weight change in the mice.
The mice were weighed every other week from day -7 to day 21 (n = 3 mice/group/period). The average weight of each group on day -7 was regarded as 100%. Data are expressed as the mean ± S.D. Differences between the comparison groups were considered statistically significant when p < 0.05 (*). N.S.: not significant; a: DSS+1415 group compared with Normal cont. group; b: DSS+1678 group compared with DSS cont. group.
Fig 3.
The pathosis of each mouse was assessed based on the DAI score every other week from day 0 to day 21 (n = 3 mice/group/period). Data are expressed as the mean ± S.D. Differences between the comparison groups were considered statistically significant when p < 0.05 (*). N.S.: not significant.
Fig 4.
Confirmation of intestinal bacterial diversity using DGGE analysis (A: day -7; B: day 21). DGGE analysis was carried out using DNA extracted from the feces of 3 animals in each group. DGGE results on day -7 and day 21 showed a significant difference in intestinal constituent bacteria. The number of bands and each band density indicate the approximate number of bacterial species, and bacterial cells, respectively.
Fig 5.
Representative HE-stained sections of mouse distal colon at day 21.
All sections were digitized under ×4 and ×40 magnification and images were captured. Among the DSS treatment groups, especially in the DSS cont. group and the DSS+1678 group, mucosal layer damage and enterocyte loss were remarkable, and severe inflammation was observed (arrow).
Fig 6.
The HIS of each group was calculated from HE-stained images of each colon tissue sample (n = 3 mice/group). Data are expressed as mean ± S.D. Differences between the comparison groups were considered statistically significant when p < 0.05 (*). N.S.: Not significant.
Fig 7.
Morphological assessment of the colon of each mouse group.
Colon tissue (cecum-rectum) obtained by autopsy every week from day 0 to day 21. A representative example of a colon with the average length from each group shown.
Fig 8.
Growth rate of colon from day 0.
The growth rate of the colon at day 21 was calculated based on colon length at day 0 (n = 3 mice/group). Data are expressed as mean ± S.D. Differences between the comparison groups were considered statistically significant when p < 0.05 (*). N.S.: Not significant.
Fig 9.
mRNA expression of factors related to inflammation and pro-inflammatory cytokines in the colon.
RT-qPCR analysis was performed using day 21 samples, which showed the greatest differences among the groups, from the results of the assessment of mouse pathosis. The results are expressed as relative expression ratios to the Normal cont. group. Data are expressed as the mean ± S.D. (n = 3 mice/group). Differences between the comparison groups were considered statistically significant when p < 0.05 (*). N.S.: not significant.
Fig 10.
Concentrations of SCFAs in mouse feces.
HPLC analysis was performed using day 21 samples, which showed the greatest difference among each group, from the results of the assessment of mouse pathosis. Data are expressed as the mean ± S.D. (n = 3 mice/group/period). Differences between the comparison groups were considered statistically significant when p < 0.05 (*). N.S.: not significant.
Fig 11.
ELISA analysis was performed using day 21 samples, which showed the greatest difference among each group, from the results of the assessment of mouse pathosis. Data are expressed as the mean ± S.D. (n = 3 mice/group/period). Differences between comparison groups were considered statistically significant when p < 0.05 (*). N.S.: not significant.