The Journal of Nutritional Biochemistry

Vitamin D is known for its immunosuppressive effects on T cells, suppressing Th1 and Th17 and promoting Treg differentiation. Th1 cells contribute to inflammatory responses such as inflammatory cytokine production and macrophage activation, which accelerate the progression of atherosclerosis. However, the mechanisms underlying the modulation of T cell functions by vitamin D in atherosclerosis have not been investigated. This study analyzed the gene expression profiles of T cells, using RNA-seq transcriptome analysis, to investigate the effects of in vitro vitamin D treatment on T cell differentiation and signal transduction pathways in Ldlr knock-out (Ldlr −/−) mice. C57BL/6 mice were randomly assigned to two groups and fed a control diet (CON) or a Western diet (WD) for 16 weeks, while Ldlr −/- mice (LDLR−/−) were fed a Western diet. Splenic T cells were isolated and stimulated with anti-CD3e and anti-CD28 mAb for 48 hours with or without 10 nM 1,25(OH)2D3. RNA sequencing was performed, followed by KEGG and GO enrichment analyses. Populations of T cell subsets and cytokine production were measured to assess T cell lineage differentiation. The JAK-STAT, HIF-1, and calcium signaling pathways of Ldlr −/− mice significantly differed from those of control mice, and 1,25(OH)2D3 treatment affected MAPKKK binding molecular function of Ldlr −/− mice. Percentages of Th1 cells and IL-17 production were significantly reduced by 1,25(OH)2D3 treatment in all three mouse groups. These results suggest that 1,25(OH)2D3 has anti-inflammatory effects in atherosclerosis and is involved in cell signaling pathways that could prevent disease progression by regulating T cell differentiation and effector functions.