title: Zinc deficiency suppresses the development of oral tolerance in rats.
abstract: Oral tolerance is a specific immune unresponsiveness to food antigens to prevent hypersensitivity reactions. We investigated whether zinc deficiency affects oral tolerance. Rats were fed a control (C) or zinc-deficient (ZD) diet, or pair-fed (PF) to ZD rats for 28 d. Beginning on d 7, rats were administered ovalbumin (OVA) orally to induce tolerance, or PBS 3 times/wk, and were then immunized by OVA injection. The proliferation of mesenteric lymph node (MLN) and spleen lymphocytes after in vitro OVA stimulation and the delayed-type hypersensitivity were higher in OVA-fed ZD than in OVA-fed C rats and not different between OVA- and PBS-fed ZD rats, indicating a suppression of tolerance. Lymphocyte proliferation did not differ between PF and C rats. Expressions of cytokines involved in oral tolerance, i.e., interleukin (IL)-4, IL-10 and transforming growth factor-beta, were higher in OVA- than in PBS-fed C rats, but not in ZD rats. Apoptosis was higher in OVA- than in PBS-fed C rats but not different between OVA- and PBS-fed ZD rats. Inflammation and ulcerations that were not present in ZD rats on d 7 (ZD(7)) developed in OVA- or PBS-fed ZD rats. Compared with ZD(7) rats, tumor necrosis factor-alpha and cytokine-induced neutrophil chemoattractant were higher in OVA- and PBS-fed ZD rats, whereas interferon-gamma increased only in OVA-fed ZD rats. In conclusion, zinc deficiency suppresses oral tolerance through dysregulation of cytokine expression and lack of antigen-specific clonal deletion. We suggest that abrogation of tolerance may lead to development of mucosal inflammation and damage.
authors.affiliation: Istituto Nazionale di Ricerca per gli Alimenti e la Nutrizione, 00178 Roma, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Finamore
authors.forename: Marianna
authors.initials: M
authors.lastname: Roselli
authors.forename: Nicolò
authors.initials: N
authors.lastname: Merendino
authors.forename: Fabio
authors.initials: F
authors.lastname: Nobili
authors.forename: Francesco
authors.initials: F
authors.lastname: Vignolini
authors.forename: Elena
authors.initials: E
authors.lastname: Mengheri
mesh_terms: D000818:Animals; D005512:Food Hypersensitivity / Q000209:etiology / Q000276:immunology*; D007413:Intestinal Mucosa / Q000276:immunology; D007583:Jejunum / Q000201:enzymology / Q000473:pathology; D008297:Male; D010047:Ovalbumin / Q000008:administration & dosage / Q000276:immunology*; D009195:Peroxidase / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013154:Spleen / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology; D015032:Zinc / Q000172:deficiency*
chemical_list: D014409:Tumor Necrosis Factor-alpha; D010047:Ovalbumin; D009195:Peroxidase; D015032:Zinc