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.


CONCLUSIONS
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.
Zold
E
E
Division of Clinical Immunology, 3rd Department of Medicine, Medical and Health Science Centre, University of Debrecen, Hungary.
Szodoray
P
P
Kappelmayer
J
J
Gaal
J
J
Csathy
L
L
Barath
S
S
Gyimesi
E
E
Hajas
A
A
Zeher
M
M
Szegedi
G
G
Bodolay
E
E
D000328:Adult; D001323:Autoantibodies / Q000097:blood; D050071:Bone Density Conservation Agents / Q000009:adverse effects* / Q000627:therapeutic use; D003240:Connective Tissue Diseases / Q000276:immunology*; D016207:Cytokines / Q000097:blood / Q000378:metabolism; D005260:Female; D051858:Forkhead Transcription Factors / Q000097:blood / Q000378:metabolism; D006706:Homeostasis / Q000187:drug effects* / Q000276:immunology; D006801:Humans; D006887:Hydroxycholecalciferols / Q000009:adverse effects* / Q000627:therapeutic use; D020381:Interleukin-17 / Q000097:blood / Q000378:metabolism; D008875:Middle Aged; D050378:T-Lymphocytes, Regulatory / Q000187:drug effects* / Q000276:immunology; D058504:Th17 Cells / Q000187:drug effects* / Q000276:immunology; D014807:Vitamin D / Q000097:blood / Q000378:metabolism; D014808:Vitamin D Deficiency / Q000188:drug therapy / Q000276:immunology*; D055815:Young Adult
D001323:Autoantibodies; D050071:Bone Density Conservation Agents; D016207:Cytokines; C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; D006887:Hydroxycholecalciferols; D020381:Interleukin-17; D014807:Vitamin D; C008088:alfacalcidol