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Br J Nutr. 2019 Nov 28;122(10):1120-1129. doi: 10.1017/S0007114519001922. Epub 2019 Aug 9.

High dietary vitamin C intake reduces glucocorticoid-induced immunosuppression and measures of oxidative stress in vitamin C-deficient senescence marker protein 30 knockout mice.

Author information

1
Department of Medical Life Systems, Faculty of Life and Medical Sciences, Doshisha University, 1-3 Tatara Miyakodani, Kyotanabe City, Kyoto 610-0321, Japan.
2
Molecular Microbiology Group, Department of Infectious Diseases, Tropical Biosphere Research Center, University of the Ryukyus, Senbaru 1, Nishihara, Nakagami-gun, Okinawa 903-0213, Japan.
3
Department of Pharmaceutical Sciences, Nihon Pharmaceutical University, Komuro 10281, Ina-machi, Kitaadachi-gun, Saitama 362-0806, Japan.
4
Molecular Regulation of Aging, Tokyo Metropolitan Institute of Gerontology, Tokyo 173-0015, Japan.

Abstract

Vitamin C (VC) is a vital micronutrient for humans and some other mammals and also has antioxidant activity. Stress-induced elevation of glucocorticoid production is well known to cause immunosuppression. The present study evaluated the effect of high VC intake on glucocorticoid-induced immune changes in mice. Senescence marker protein 30 knockout mice with genetic VC deficiency were fed a diet containing the recommended VC content (20 mg/kg per d; 0·02 %VC group) or a high VC content (200 mg/kg per d; 0·2 %VC group) for 2 months, then dexamethasone was given by intraperitoneal injection. After administration of dexamethasone, the plasma ascorbic acid concentration decreased significantly in the 0·02 %VC group and was unchanged in wild-type C57BL/6 mice on a VC-deficient diet (wild-type group), while it was significantly higher in the 0·2 %VC group compared with the other two groups. In the 0·02 %VC and wild-type groups, dexamethasone caused a significant decrease in the cluster of differentiation (CD)4+ and CD8+ T cells among splenocytes as well as a significant decrease in IL-2, IL-12p40 and interferon-γ protein production by splenocytes and a significant decrease in T-cell proliferation among splenocytes. In the 0·2 %VC group, these dexamethasone-induced immunosuppression improved when compared with the other two groups. In addition, reduction in the intracellular levels of ascorbic acid, superoxide dismutase and glutathione in splenocytes by dexamethasone as well as elevation in thiobarbituric acid-reactive substances were significantly suppressed in the 0·2 %VC group. These findings suggest that high dietary VC intake reduces glucocorticoid-induced T-cell dysfunction by maintaining intracellular antioxidant activity.

KEYWORDS:

Glucocorticoids; Immune function; Oxidative stress; SMP30-KO mice; Vitamin C

PMID:
31647039
DOI:
10.1017/S0007114519001922

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