Oral administration of antigens from intestinal flora anaerobic bacteria reduces the severity of experimental acute colitis in BALB/c mice

Homeostasis between indigenous intestinal flora and host response may be br oken in inflammatory bowel disease. The present study explores whether repe ated oral administration of intestinal flora antigens can protect mice agai nst dextran sodium sulphate (DSS)-induced colitis. Sonicates of Gram-positi ve, Gram-negative, or anaerobic resident bacteria isolated from mouse intes tinal flora were fed to BALB/c mice by gastric gavage, with or without chol era toxin. After four weekly doses of 1 mg of these antigen preparations (o r of PBS as control), DSS colitis was induced. One week later colitis was e valuated by clinical scores and histology. Mice fed a pool of the three son icates had decreased inflammation scores (5 (1-14); median (range)) compare d with PBS-fed control animals (15 (7-19); P < 0.05). Decreased inflammatio n was observed in mice fed anaerobic bacteria antigens (7 (6-11); P < 0.05 versus control), but not in mice fed a pool of Gram-positive and -negative sonicates (16 (12-16)). Inflammation scores of mice fed antigens with chole ra toxin were similar to those of PBS-fed control animals. DSS-induced coli tis can be suppressed by oral administration of normal intestinal flora ant igens containing anaerobes.