Association between vitamin D, oestradiol and interferon-gamma in female patients with inactive systemic lupus erythematosus: A cross-sectional study

Abstract

Objectives To investigate possible associations between 25-hydroxyvitamin D₃ (25(OH)D₃), oestradiol (E₂) and IFN-gamma (IFNγ) in female patients with inactive systemic lupus erythematosus (SLE). Methods Female patients with inactive SLE and age-matched healthy controls were recruited into this cross-sectional study. Serum concentrations of 25(OH)D_3, E₂ and IFNγ were measured by radioimmunoassay with gamma-counters and enzyme-linked immunosorbent assay. Results 36 patients and 37 controls were enrolled. In patients with SLE, the concentration of 25(OH)D₃ was lower and E₂ was higher compared with controls. In vitamin D deficient (i.e., 25(OH)D₃≤20 ng/ml) patients, IFNγ was 150% higher compared with patients with 25(OH)D₃>20 ng/ml and controls. The concentration of E₂ was higher in all patients compared with controls independently of the vitamin D level. A difference was found between patients and controls in the correlation of 25(OH)D₃ with E₂ and a positive correlation was found between E₂ and IFNγ in all participants. Conclusions Our results suggest that E₂ may have a strong modulating effect on vitamin D function which is significant only at low concentration of E₂.

Keywords: Vitamin D; interferon-gamma; oestradiol; systemic lupus erythematosus.

Figure 1.

Association of 25(OH)D₃ with systemic lupus erythematosus (SLE) flair at different values of oestradiol (E₂) in female patients (n=36) with inactive disease.