title: Further evidence regarding the effect of dietary protein on oral tolerance against beta-lactoglobulin through Th1-mediated immune response in mice.
abstract: Oral tolerance is a potential strategy for preventing or minimizing aberrant immune responses. Although, oral tolerance has been extensively studied, to date the effects of dietary protein on the induction of oral tolerance are poorly understood. We have previously shown that restricted dietary protein induces oral tolerance to ovalbumin. This study was designed to investigate whether or not such tolerance occurs with beta-lactoglobulin (BLG) instead of ovalbumin (OVA) and if the tolerance resulting from this feeding regimen involves Th1-mediated immune response. Female BALB/c mice fed either 20% or 5% dietary protein were given 5 mg BLG or water orally for four consecutive days and then immunized intraperitoneally (ip) twice with BLG at 3-wk intervals. Oral tolerance induction was compared in BLG-fed and water-fed mice by measuring total IgE, BLG-specific antibodies, footpad reactions, splenocyte proliferation, and cytokine production. When mice were given BLG orally before ip immunization, the Th1-mediated immune responses (production of IL-2, IFN-gamma, and IgG2a) were significantly reduced, whereas the Th2-mediated immune responses (production of IL-4 and IgG1) were unchanged. The Th1-mediated immune responses were markedly down-regulated in mice fed 5% protein as compared to those in mice fed 20% protein. Moreover, the production of total IgE, BLG-specific IgE, splenocyte proliferation, and footpad reactions were more reduced in mice fed 5% protein than those in mice fed 20% protein. The present study provides evidence that dietary protein plays an important role in the induction of oral tolerance against BLG as the result of, clear down-regulation of Th1 helper activity accompanied by a reduction in IgE.
authors.affiliation: Department of Food Microbiology, School of Nutrition, Faculty of Medicine, The University of Tokushima, Tokushima 770-8503, Japan.
authors.forename: Sherin
authors.initials: S
authors.lastname: Ahmed
authors.forename: Mohammed A
authors.initials: MA
authors.lastname: Satter
authors.forename: Shigeru
authors.initials: S
authors.lastname: Yamamoto
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Maeda
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Minato
authors.forename: Fusao
authors.initials: F
authors.lastname: Ota
mesh_terms: D000284:Administration, Oral; D000818:Animals; D016207:Cytokines / Q000276:immunology; D004044:Dietary Proteins / Q000097:blood / Q000276:immunology / Q000494:pharmacology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D007108:Immune Tolerance / Q000187:drug effects / Q000502:physiology*; D007136:Immunoglobulins / Q000097:blood / Q000276:immunology; D007782:Lactoglobulins / Q000097:blood / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D013154:Spleen / Q000276:immunology; D018417:Th1 Cells / Q000276:immunology*
chemical_list: D016207:Cytokines; D004044:Dietary Proteins; D007136:Immunoglobulins; D007782:Lactoglobulins