Effects of Vitamin D Supplementation on CD4+ T Cell Subsets and mTOR Signaling Pathway in High-Fat-Diet-Induced Obese Mice

Obesity is associated with an impaired balance of CD4(+) T cell subsets. Both vitamin D and obesity have been reported to affect the mTOR pathway. In this study, we investigated the effects of vitamin D on CD4(+) T cell subsets and the mTOR pathway. Ten-week-old male C57BL/6 mice were divided into four groups and fed diets with different fat (control or high-fat diets: CON or HFD) and vitamin D contents (vitamin D control or supplemented diets: vDC or vDS) for 12 weeks. T cells purified by negative selection were stimulated with anti-CD3/anti-CD28 mAbs and cultured for 48 h. The percentage of CD4(+)IL-17(+) T cells was higher in the vDS than vDC groups. The CD4(+)CD25(+)Foxp3(+) T cells percentage was higher in HFD than CON groups. The phospho-p70S6K/total-p70S6K ratio was lower in vDS than vDC, but the phospho-AKT/total-AKT ratio was higher in vDS than vDC groups. Hif1 alpha mRNA levels were lower in vDS than vDC groups. These findings suggest HIF1 alpha plays an important role in vitamin-D-mediated regulation of glucose metabolism in T cells, and dietary vitamin D supplementation may contribute to the maintenance of immune homeostasis by regulating the mTOR pathway in T cells.

Automated summary

The study showed that vitamin D has effects on CD4(+) T cell subsets and the mTOR pathway, especially in the context of obesity. Additionally, Hif1 alpha was found to play an important role in vitamin D-mediated regulation of T cell glucose metabolism, and dietary vitamin D supplementation may contribute to maintaining immune homeostasis by regulating the mTOR pathway in T cells.