Effects of appendectomy and oral tolerance on dextran sulfate sodium colitis

AIM： To evaluate the concomitant effects of appendec- tomy and oral tolerance on colitis.METHODS： Delayed-type hypersensitivity （DTH） was investigated at a 7-d interval after ovalbumin （OVA） ad- ministration and immunization under normal and colitis conditions in appendectomized or sham-operated mice. Pathological scores for the colon were graded after in- gestion of colon-extracted protein （CEP） and induction of dextran sulfate sodium （DSS） colitis in appendecto- mized or sham-operated mice. Thereafter, Thl and Th2 in Peyer＇s patches and spleen lymphocytes were de- tected in CEP-treated and bovine serum albumin （BSA）-treated control mice.RESULTS： In appendectomized mice, DTH was not inhibited at day 7 after OVA administration and at the initial phase of DSS colitis, whereas it was inhibited at day 14 and day 21. However, in sham-operated mice, it was inhibited during the whole procedure and the onset of DSS colitis. The protective role of CEP against DSScolitis was present in sham-operated mice, with pre- dominant improvement of colonic pathological changes, while vanished in the appendectomized mice. A shift from Thl to Th2 in Peyer＇s patches resulted from a de- crease of Thl cells with the ingestion of CEP. Compared with BSA in the sham-operated group, no predominant changes were observed in the appendectomized mice.CONCLUSION： Appendectomy interferes with the pro- tective role of CEP in DSS colitis via a shift from Th2 to Thl during oral tolerance induction.