1,25-Dihydroxyvitamin D₃ modulates T cell differentiation and impacts on the production of cytokines from Chinese Han patients with early rheumatoid arthritis

To study the effects of 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) on the differentiation of T cells and the levels of cytokines in patients with early rheumatoid arthritis (eRA). The levels of Th1, Th2, Th17, and Treg cells were detected with BDFACS Calibur flow cytometer. The expression of IFN-ɤ, TNF-α, IL-2, IL-4, IL-6, IL-10, IL-17, and IL-22 was examined in 54 patients with eRA using a cytometric bead array (CBA). After 72 h of incubation of PBMCs from eRA patients with 1,25(OH)₂D₃, the levels of IFN-ɤ, TNF-α, IL-2, IL-6, and IL-17 significantly decreased compared to those of the control. 1,25(OH)₂D₃ had no significantly impact on the levels of IL-4, IL-10, and IL-22. The proportion of Th17 and the ratio of Th17/Treg significantly decreased in 1,25(OH)₂D₃-treated groups compared to those of the control. 1,25(OH)₂D₃ had no significantly impact on the proportion of Th1, Th2, Treg, and the ratio of Th1/Th2. Although no statistically significant difference was observed, proportion of Th1 was decreased after 1,25(OH)₂D₃ treatment compared with anti-CD3/CD28 only. The present study demonstrated that 1,25(OH)₂D₃ inhibited the synthesis of specific cytokines: Th1 (IFN-ɤ) and Th17 (IL-17, IL-22, IL-6, TNF-α) might upregulated Th2 cytokine (IL-4), which indicated the possible immunoregulatory roles and bone-sparing effects of 1,25(OH)₂D₃ in eRA through modulation of the Th1 and Th17 cytokine balance.