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

Br J Nutr. 2015 Feb 28;113(4):603-9. doi: 10.1017/S0007114514003857. Epub 2015 Jan 22.

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.

Keywords: Naive T cells.

MeSH terms

  • Aging*
  • Animals
  • Antioxidants / administration & dosage
  • Antioxidants / adverse effects
  • Antioxidants / analysis
  • Antioxidants / therapeutic use
  • Ascorbic Acid / administration & dosage
  • Ascorbic Acid / adverse effects
  • Ascorbic Acid / blood
  • Ascorbic Acid / therapeutic use*
  • Ascorbic Acid Deficiency / blood
  • Ascorbic Acid Deficiency / diet therapy
  • Ascorbic Acid Deficiency / metabolism
  • Ascorbic Acid Deficiency / physiopathology
  • Atrophy
  • Calcium-Binding Proteins / genetics
  • Calcium-Binding Proteins / metabolism*
  • Dietary Supplements* / adverse effects
  • Immunologic Factors / administration & dosage
  • Immunologic Factors / adverse effects
  • Immunologic Factors / blood
  • Immunologic Factors / therapeutic use*
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Leukocyte Count
  • Lymphatic Diseases / etiology
  • Lymphatic Diseases / immunology
  • Lymphatic Diseases / pathology
  • Lymphatic Diseases / prevention & control*
  • Macrophages / immunology
  • Macrophages / metabolism
  • Macrophages / pathology
  • Male
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Organ Size
  • Random Allocation
  • Specific Pathogen-Free Organisms
  • Spleen / immunology
  • Spleen / metabolism
  • Spleen / pathology
  • T-Lymphocyte Subsets / immunology
  • T-Lymphocyte Subsets / metabolism
  • T-Lymphocyte Subsets / pathology
  • Thymus Gland / immunology
  • Thymus Gland / metabolism
  • Thymus Gland / pathology*

Substances

  • Antioxidants
  • Calcium-Binding Proteins
  • Immunologic Factors
  • Intracellular Signaling Peptides and Proteins
  • Rgn protein, mouse
  • Ascorbic Acid