Zinc influences innate and adaptive immune responses in mice with enterotoxigenic Escherichia coli-induced diarrhea

Enterotoxigenic Escherichia coli (ETEC) is a major cause of diarrheal disease. Information is limited on the effect of zinc on immune responses to diarrhea induced by ETEC. We investigated the immunological effects of zinc treatment in mice with diarrhea caused by ETEC. Our study included a total of 6 C57BL/6 mice aged 7-8 weeks that were treated with a high zinc diet for 2 weeks as well as 6 mice with ETEC-induced diarrhea that were not treated with zinc (UT). Six control mice (CON) of the same age group were also studied. The UT group showed more severe disruption to intestinal morphogenesis than ZT group. Serum zinc, complement C3, IgG, and IgM concentrations were higher in the ZT group than those in UT group but did not differ from those in the CON group. Phagocytic activity in mice in ZT group was greater than that in the UT group. However, oxidative burst capacity was lower in ZT group than in the UT group. The CD4/CD8 T-cell ratio in ZT group was higher than that in the UT group. Increased responses including complement C3, phagocytic activity, and changes in T-cell phenotypes suggests that zinc treatment enhances innate and adaptive immunity against ETEC infection in mice.