Fig. 4

DSS induced colitis model of Balb/c mice. a Experimental design of seven-week-old Balb/c mouse model to evaluate the DSS exposure and bacterial inoculation. Six groups with different treatment were used, with each group having five mice. Body weight was measured daily, and organ was harvested immediately after euthanasia. b Representative images of H&E stained colon sections showed effect of DSS and bacterial inoculation on histopathological changes. Colon tissue from groups ‘Water’, ‘E. rectale + water’ and ‘F. nucleatum + water’ did not show any specific pathologic changes. Colon tissue from groups ‘DSS’ and ‘F. nucleatum + DSS’ showed rupture of the epithelium, segmental regions of marked acute inflammatory cell infiltration, ulceration, different size and shape of intestinal crypts, local destruction of crypts, which were indicated by arrows. Group ‘E. rectale + DSS’ had multiple crypts destruction and increased severity of the same histopathological changes seen in groups ‘DSS’ and ‘F. nucleatum + DSS’. c Graph indicated the histology scores of six groups. Data were presented as mean ± STD. P-values were determined using the t-test. Other groups were compared with group ‘Water’. Groups ‘E. rectale + DSS’ and ‘F. nucleatum + DSS’ were compare with group ‘DSS’. *P < 0.05 represents a significant difference from group ‘Water’, #P < 0.05 represents a significant difference from group ‘DSS’. d–g Effect of DSS and bacterial inoculation on colon length and spleen weight. Other groups were compared with group ‘Water’. Groups ‘E. rectale + DSS’ and ‘F. nucleatum + DSS’ were compare with group ‘DSS’. *P < 0.05 represents a significant difference from group ‘Water’, #P < 0.05 represents a significant difference from group ‘DSS’. d Representative gross images and measurements of mouse colons with cecums still attached. Arrows indicate the colon-cecum junction as a landmark for colon length measurement. e Diagram of colon length. Column indicated the mean ± STD (n = 5 mice per group). f Gross picture of spleen. g Spleen weight measured at the time of harvested. Column indicated the mean ± STD (n = 5 mice per group). h–j Body weight and stool grading of mice. Black arrow indicates the day of bacterial inoculation. Blue arrow indicates the day that mice began to drink water without DSS. Points show the mean from five mice or five stool samples, and standard deviations are shown as error bars. h Mice body weight alterations during the 17-day experiments. i Daily stool grading during the 17-day experiments. Stool grade 0 represents no occult or gross blood, stool grade 1 represents occult blood, stool grade 2 represents gross blood. j Other groups were compared with group ‘Water’ or group ‘DSS’. Days represent significant difference from group ‘Water’ or group ‘DSS’ (P < 0.05). There are no significant difference among group ‘Water’, ‘E. rectale + water’ and ‘F. nucleatum + water’