Oral administration of heat killed Tsukamurella inchonensis enhances immune responses and intestinal function in mice

We studied the effects of heat-killed Tsukamurella inchonensis on immune parameters and intestinal structure in mice. Mice were treated with three doses of bacteria (5 × 107, 1 × 108 and 2 × 108 CFU/mouse) consecutively for seven days. Body weight, delayed type hypersensitivity response, relative organ weight, and haemagglutination titres were studied in different groups of animals. Villus height, villus width, villus/crypt ratio, crypt depth and goblet cell and intestinal epithelial lymphocyte density in villi were also determined. There was no significant increase in liver, spleen and kidney weights at any dose. Chicken red blood cell was used as a model antigen in the humoral and cellular immune response tests and Tsukamurella inchonensis elicited a significant (P < 0.05) increase in the delayed type hypersensitivity response at doses of 2 × 108 CFU/mouse. In the haemagglutination titres test, Tsukamurella inchonensis showed a modulatory effect at a dose of 2 × 108 CFU/mouse. There were clear increases in the height of villi and depth of crypts in all three treated groups, but no significant effects on villus/crypt ratio and villus width. Goblet cell density was increased significantly only in high dose-treated mice, while intestinal epithelial lymphocyte density was increased significantly in medium and high dose-treated mice. Overall, Tsukamurella inchonensis showed a stimulatory effect on immune functions and enhanced immune barrier function in the intestines of mice.