The immunopathological role of vitamin D in patients with SLE: data from a single centre registry in Hungary.

OBJECTIVES: Disproportionate vitamin D levels may play an important role in the development of certain systemic autoimmune and rheumatic diseases. The aim of the present study was to investigate the prevalence of vitamin D insufficiency in patients with systemic lupus erythematosus (SLE) and to compare serological and clinical parameters in patients with different vitamin D levels from a single centre registry in Central-Eastern Europe. METHODS: A total of 177 patients with SLE were enrolled in the study. 25-Hydroxyvitamin D [25(OH)D] levels were measured by chemiluminescent immunoassay (CLIA). Autoantibody profiles, complement 3 (C3) and C4, clinical symptoms, and disease activity (using the SLE disease activity index, SLEDAI) of the patients were assessed. RESULTS: Vitamin D concentration in the total SLE group investigated was 26.88 ± 13.25 ng/mL. Vitamin D levels were normal (≥ 30 ng/mL) in 18.1% of patients, insufficient (15-30 ng/mL) in 44.6%, and deficient (< 15 ng/mL) in 37.3%. The vitamin levels were significantly reduced in postmenopausal compared to premenopausal patients (p = 0.02). Patients with pericarditis (p = 0.013), neuropsychiatric diseases (p = 0.01), and deep vein thrombosis (p = 0.014) had reduced vitamin D levels. SLEDAI score was significantly increased in patients with reduced vitamin D levels (p = 0.038). Anti-double-stranded (ds)DNA autoantibody concentrations increased from normal to insufficient and further increased from insufficient to deficient patient subsets (p = 0.021). Anti-Smith antigen (anti-Sm) concentrations increased (p < 0.001), C4 levels decreased (p = 0.027), and immunoglobulin (Ig)G concentration increased (p = 0.034) in patients with reduced vitamin D levels. CONCLUSIONS: Our data suggest that vitamin D deficiency in SLE may play a role in perpetuation of the disease.

Impaired regulatory T-cell homeostasis due to vitamin D deficiency in undifferentiated connective tissue disease.

OBJECTIVE: The aim of this study was to perform a quantitative and functional analysis of natural CD4+CD25(high)Foxp3+ regulatory T cells (nTregs) and CD4+IL-17+ T cells, and to assess the serum levels of proinflammatory cytokines in patients with undifferentiated connective tissue disease (UCTD) before and after 5 weeks of 0.5 µg/day alfacalcidol supplementation. METHODS: Twenty-five patients with UCTD were enrolled in an open-label trial of alfacalcidol. Plasma levels of 25-hydroxyvitamin D [25(OH)D] were assessed by a high-performance liquid chromatography (HPLC) method. Flow cytometry was used for the quantification of nTregs and the IL-17 expression of T-helper (Th)17 cells. The serum concentrations of cytokines interleukin (IL)-12, interferon (IFN)-γ, IL-23, IL-17, IL-6, and IL-10 were measured by an enzyme-linked immunosorbent assay (ELISA). RESULTS: Treatment with alfacalcidol raised 25(OH)D levels from a mean of 23.5 ± 5.6 to 34.5 ± 7.4 ng/mL (p = 0.059; NS). Alfacalcidol treatment decreased both Th1- (IL-12 and IFN-γ) and Th17-related (IL-23, IL-17, IL-6) cytokine levels in UCTD patients, while the soluble IL-10 level increased (IL-12: 156.7 ± 75.2 vs. 87.5 ± 42.1 pg/mL, p < 0.001; IFN-γ: 41.5 ± 12.0 vs. 21.7 ± 9.9 pg/mL, p < 0.001; IL-23: 385.2 ± 82.2 vs. 210.0 ± 69.3 pg/mL, p < 0.001; IL-17: 37.8 ± 9.6 vs. 17.8 ± 4.5 pg/mL, p = 0.009; IL-6: 39.4 ± 11.3 vs. 23.5 ± 6.3 pg/mL, p < 0.001, IL-10: 8.4 ± 3.0 vs. 21.4 ± 9.7 pg/mL, p < 0.001). Alfacalcidol improved the Th17/nTreg imbalance, as it inhibited the IL-17 expression of Th17 cells, and increased the number of nTregs. The alfacalcidol might increase the capacity of nTreg cells to suppress the proliferation of autologous CD4+CD25⁻ cells. CONCLUSION: Our findings support the idea that vitamin D influences the Th17/nTreg imbalance in vitamin D-insufficient patients with UCTD and could be beneficial in the management of the disease.