Vitamin D Supplementation Promotes Regulatory T-Cells to Maintain Immune Homeostasis After Surgery for Early Stages of Colorectal Cancer.

BACKGROUND/AIM: Vitamin D (VD) affects the regulation of the immune system, including the differentiation and function of regulatory T-cells (Tregs). Tregs play an important role in maintaining immune homeostasis in patients with colorectal cancer (CRC). The effects of VD on Treg-associated immune function were investigated in Thai patients in the early stages of CRC.

MATERIALS AND METHODS

Twenty-eight patients were randomized to one of two groups: Untreated or treatment with VD for 3 months. Whole blood samples were collected at baseline, and at 1 and 3 months. Peripheral blood mononuclear cells were isolated and the populations of forkhead box P3-positive Treg cells was analyzed by flow cytometry. The levels of Treg-associated cytokines, interleukin 10 (IL-10) and transforming growth factor beta 1 (TGF-β1), were measured by enzyme-linked immunosorbent assays.

RESULTS

Serum VD levels of the VD-treated group were significantly increased at 1 (p=0.017) and 3 months (p<0.001) compared to the untreated control group. The mean percentage of Tregs was maintained between 1 and 3 months in the VD-treated group. At 3 months, the untreated group had significantly lower Treg levels than the VD-treated group (p=0.043). Serum IL-10 levels of the VD-treated group were statistically increased at 1 month compared to the control group (p=0.032). No significant difference in serum TGF-β1 levels was observed between the two groups. However, the TGF-β1 level in the VD-treated group at 1 month was lower than that of the control.

CONCLUSION

Our findings suggest that VD supplementation can maintain immune responses in the early stages of CRC, helping to control Treg function. Therefore, VD should be supplemented to maintain immune homeostasis, especially in patients with vitamin D deficiency.