title: High dietary intake of vitamin C suppresses age-related thymic atrophy and contributes to the maintenance of immune cells in vitamin C-deficient senescence marker protein-30 knockout mice.
abstract: Vitamin C (VC) is an essential nutrient for humans and certain other animals. It has antioxidant properties and has been reported to ameliorate oxidative damage to lipids, DNA and proteins. However, the effects of VC on immune function are poorly understood, especially the influence of long-term high-dose VC intake on the number and function of immune cells. In the present study, to evaluate the immune effects of VC, VC-deficient senescence marker protein-30 knockout (SMP30KO) mice were fed a diet containing the recommended level of VC (20 mg/kg per d; 0·02 % VC) or a high level of VC (200 mg/kg per d; 0·2 % VC) for 1 year. The plasma VC concentration of the 0·02 % group was the same as that of age-matched C57BL/6 mice after 1 year of feeding; however, plasma VC concentration and thymus weight were significantly higher in the 0·2 % VC group than in the 0·02 % VC group. The total counts of leucocytes, lymphocytes, granulocytes and monocytes in the peripheral blood, as well as the number of splenocytes and thymocytes, were all significantly higher in the 0·2 % VC group than in the 0·02 % VC group. In addition, the number of naive T cells in peripheral blood lymphocytes, the number of memory T-cell populations in splenocytes, and the number of cluster of differentiation (CD)4⁺CD8⁺ or CD4⁺CD8⁻ or CD4⁻CD8⁺ T cells in thymocytes were all markedly higher in the 0·2 % VC group than in the 0·02 % VC group after 1 year of dietary treatment. These results suggest that a long-term high-dose intake of VC is effective in the maintenance of immune cells, partly through the suppression of age-related thymic involution in VC-deficient SMP30KO mice.
authors.affiliation: Research and Development Institute, House Wellness Foods Corporation,3-20 Imoji,Itami664-0011,Japan.
authors.forename: Ryusei
authors.initials: R
authors.lastname: Uchio
authors.affiliation: Research and Development Institute, House Wellness Foods Corporation,3-20 Imoji,Itami664-0011,Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Hirose
authors.affiliation: Research and Development Institute, House Wellness Foods Corporation,3-20 Imoji,Itami664-0011,Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Murosaki
authors.affiliation: Research and Development Institute, House Wellness Foods Corporation,3-20 Imoji,Itami664-0011,Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Yamamoto
authors.affiliation: Molecular Regulation of Aging, Tokyo Metropolitan Institute of Gerontology,Tokyo173-0015,Japan.
authors.forename: Akihito
authors.initials: A
authors.lastname: Ishigami
mesh_terms: D000375:Aging; D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage / Q000009:adverse effects / Q000032:analysis / Q000627:therapeutic use; D001205:Ascorbic Acid / Q000008:administration & dosage / Q000009:adverse effects / Q000097:blood / Q000627:therapeutic use*; D001206:Ascorbic Acid Deficiency / Q000097:blood / Q000178:diet therapy / Q000378:metabolism / Q000503:physiopathology; D001284:Atrophy; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D019587:Dietary Supplements / Q000009:adverse effects; D007155:Immunologic Factors / Q000008:administration & dosage / Q000009:adverse effects / Q000097:blood / Q000627:therapeutic use*; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D007958:Leukocyte Count; D008206:Lymphatic Diseases / Q000209:etiology / Q000276:immunology / Q000473:pathology / Q000517:prevention & control*; D008264:Macrophages / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D008297:Male; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009929:Organ Size; D011897:Random Allocation; D013047:Specific Pathogen-Free Organisms; D013154:Spleen / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D016176:T-Lymphocyte Subsets / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D013950:Thymus Gland / Q000276:immunology / Q000378:metabolism / Q000473:pathology*
chemical_list: D000975:Antioxidants; D002135:Calcium-Binding Proteins; D007155:Immunologic Factors; D047908:Intracellular Signaling Peptides and Proteins; C513324:Rgn protein, mouse; D001205:Ascorbic Acid
keywords: Naive T cells