Nutr Res Pract.  2021 Dec;15(6):673-685. 10.4162/nrp.2021.15.6.673.

Effects of in vitro vitamin D treatment on function of T cells and autophagy mechanisms in high-fat diet-induced obese mice

Affiliations
  • 1Department of Food and Nutrition, College of Human Ecology, Seoul National University, Seoul 08826, Korea
  • 2Department of Food & Nutrition, College of Health Science, The University of Suwon, Hwaseong 18323, Korea
  • 3Research Institute of Human Ecology, Seoul National University, Seoul 08826, Korea

Abstract

BACKGROUND/OBJECTIVES
Obesity is associated with the impaired regulation of T cells characterized by increased numbers of Th1 and Th17 cells and the dysregulation of vitamin D metabolism. Both obesity and vitamin D have been reported to affect autophagy; however, a limited number of studies have investigated the effects of vitamin D on T cell autophagy in obese mice. Therefore, we aimed to determine whether in vitro treatment with vitamin D affects the proliferation, function, and autophagy of T cells from obese and control mice.
MATERIALS/METHODS
Five-week-old male C57BL/6 mice were fed control or high-fat diets (10% or 45% kcal fat: CON or HFDs, respectively) for 12 weeks. Purified T cells were stimulated with anti-CD3 and anti-CD28 monoclonal antibodies and cultured with either 10 nM 1,25(OH)2D3 or 0.1% ethanol (vehicle control). The proliferative response; expression of CD25, Foxp3, RORγt, and autophagy-related proteins (LC3A/B, SQSTM1/P62, BECLIN-1, ATG12); and the production of interferon (IFN)-γ, interleukin (IL)-4, IL-17A, and IL-10 by T cells were measured.
RESULTS
Compared with the CON group, T cell proliferation tended to be lower, and the production of IFN-γ was higher in the HFD group. IL-17A production was reduced by 1,25(OH)2D3 treatment in both groups. The LC3 II/I ratio was higher in the HFD group than the CON group, but P62 did not differ. We observed no effect of vitamin D treatment on T cell autophagy.
CONCLUSIONS
Our findings suggest that diet-induced obesity may impair the function and inhibit autophagy of T cells, possibly leading to the dysregulation of T cell homeostasis, which may be behind the aggravation of inflammation commonly observed in obesity.

Keyword

Obesity; vitamin D; T lymphocytes; autophagy
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