Objectives: In addition to its known effects on bone metabolism, vitamin D may regulate immune function.
Design: We performed a randomized controlled trial (RCT) to test whether cholecalciferol supplementation can improve vitamin D status and affect the T-cell phenotype in HIV-infected youth with vitamin D insufficiency.
Methods: Fifty-two HIV-infected patients aged 8 to 26 years and with serum 25(OH) D <30 ng/mL were randomized to receive orally vitamin D3 100,000 IU or placebo every 3 months for 4 doses. Serum 25(OH)D, 1,25(OH)2D, PTH, and CD4+ T cells were assessed 3 months before baseline and at 0, 3, 6, 9, and 12 months, while Th1-, Th2-, Th17-, and Treg-subsets and T-lymphocyte vitamin D receptor were assessed at 0, 3, and 12 months.
Results: Forty-eight subjects (25 receiving vitamin D and 23 receiving placebo) completed the RCT. Cholecalciferol supplementation produced an early (3 months) decrease in PTH, a concomitant increase in 25(OH)D, and a later (6 months) increase in 1,25(OH)2D levels, all persisting at 12 months. The frequency of vitamin D insufficiency at 12 months was 20% versus 60% in the intervention versus placebo group (P = .007). Cholecalciferol supplementation had no effect on CD4+ T-cell counts but was associated with a decreased Th17:Treg ratio at 3 months.
Conclusions: In our cohort of HIV-infected youth, a 12-month cholecalciferol supplementation increased 25(OH)D and 1-25(OH)2D and decreased PTH levels but had no effect on CD4+ T-cells. However, it was associated with changes in CD4+ T-cell phenotype, warranting further investigation.