Abstract
AbstractWe investigated the impact of Zn status on the maintenance of mucosal homeostasis. Rats were fed diets containing different amounts of Zn (30, 10, 5, <1 mg Zn/kg diet) for 21 d. Serum Zn concentrations were lower in rats fed marginally Zn-deficient (MZD; 5 mg Zn/kg diet) and severely Zn-deficient (<1 mg/kg) diets but not in those fed the marginally Zn-adequate diet (10 mg/kg) or the Zn-adequate (ZA; 30 mg/kg) group (P< 0.05). However, organ weights, colonic epithelial cell proliferation, and crypt fission did not differ between the MZD and ZA groups. We then evaluated whether MZD modulated dextran sulfate sodium (DSS)-induced colonic inflammation by administering 2% DSS to the MZD and ZA groups for 7 d. Myeloperoxidase activity and TNFa production increased in response to DSS in the MZD group (P <0.03). Colonic permeability in the 2 groups did not differ after DSS administration. In a culture experiment using isolated mesenteric leukocytes, TNFα production was higher (P< 0.05) and TNF receptor type I (TNFR1) expression was detected in culture medium containing 20 and 30μmol/L of Zn compared with culture medium lacking Zn supplementation. These results suggest that MZD exacerbated colitis by modulating the immune response through the impairment of TNFα production andTNFR1expression rather than through the impairment of epithelial barrier function.
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