Vitamin D level in patients with systemic lupus erythematosus: its relationship to disease course and bone mineral density

OBJECTIVE

To determine vitamin D levels in patients with SLE and evaluate their relationship to bone mineral density (BMD) and the disease course.

METHODS

The study included 101 patients with SLE and 29 individuals in the control group. The study participants were tested for vitamin D level, erythrocyte sedimentation rate (ESR), C reactive protein (CRP), interleukin (IL)-6, osteocalcin (OC) and collagen type I C-terminal telopeptide (CTX), and the dual-energy X-ray absorptiometry was provided to assess BMD in the lumbar spine and the hip.

RESULTS

The mean serum vitamin D level was 18.98±0.88 ng/mL, and women had 25.42% lower vitamin D levels than men (p<0.05). There was no correlation between vitamin D levels and patient's age or disease course. There was a significant inverse correlation between vitamin D levels and cumulative dose of glucocorticoids (r=-0.26) and serum inflammatory markers, particularly CRP (r=-0.39), IL-6 (r=-0.37) and ESR (r=-0.15). Vitamin D level was associated with the bone turnover markers (BTMs). In women of reproductive age with vitamin D deficiency, BMD of the lumbar spine and the hip was 9.5-23.1% higher than in those with no vitamin deficiency, respectively, and the mean lumbar spine Z-score in women of reproductive age with vitamin D insufficiency and deficiency was significantly 2.0 and 2.9 times lower than in patients with normal vitamin D level.

CONCLUSIONS

Hypovitaminosis D is quite common in patients with SLE and is associated with high inflammatory activity (SLE Disease Activity Index, ESR, CRP, IL-6), severity of organ damage (Damage Index), cumulative dose of glucocorticoids, BTM changes (decrease in OC, increase in CTX) and BMD decline. Vitamin D status was not associated with the patient's age or disease course.

The role of vitamin D-synthesizing enzyme CYP27B1 in systemic lupus erythematosus

BACKGROUND

To measure the expression of 1α-hydroxylase (CYP27B1) and serum 25(OH)D concentration in systemic lupus erythematosus (SLE) and to investigate the role of CYP27B1 in SLE.

METHODS

Seventy-seven SLE patients and 35 healthy controls (HCs) were enrolled from September 2017 to January 2020. The study design is cross-sectional. mRNA expression of CYP27B1 in peripheral blood mononuclear cells (PBMCs) was measured by reverse-transcription quantitative PCR, the protein level of CYP27B1 was quantified by western blotting, and the serum level of 25(OH) D was determined by an enzyme-linked immunosorbent assay.

RESULTS

The mRNA expression of CYP27B1 in PBMCs was significantly lower in SLE patients than in HCs (p < 0.001), and the protein quantification confirmed that CYP27B1 expression was lower in SLE patients than in HCs (p = 0.001). Among SLE patients, the prevalence of lupus nephritis was higher in a subgroup with lower CYP27B1 mRNA expression than in a subgroup with normal CYP27B1 mRNA expression (41.07% vs. 14.28%, p = 0.028). The mRNA expression of CYP27B1 negatively correlated with the Systemic Lupus Erythematosus Disease Activity Index (r = -0.331, p = 0.003). Serum 25(OH)D concentration was lower in SLE patients than in HCs (37.64 ± 19.89 vs. 50.58 ± 12.74 ng/mL, mean ± SD, p = 0.003).

DISCUSSION

The expression of CYP27B1 in PBMCs may be related to SLE pathogenesis, disease activity, and nephritis.

Cytokines, 25-OH vit D and disease activity in patients with juvenile-onset systemic lupus erythematosus

BACKGROUND

Juvenile onset systemic lupus erythematosus JO-SLE patients usually exhibit a more aggressive disease course compared to adult patients. Vitamin D deficiency is proposed to be associated with increased disease activity and flares of numerous autoimmune diseases like SLE, rheumatoid arthritis, and scleroderma.

OBJECTIVE

To evaluate the level of IL-17, IFN-γ, and 25-OH Vit D in JO-SLE patients versus healthy controls, and determine the correlation of those inflammatory mediators with SLE disease activity and damage scores. Furthermore, to analyze the relationship between 25-OH Vit D levels with the inflammatory cytokines (IFN-γ and IL-17) in JO-SLE patients.

PATIENTS AND METHODS

Fifty JO-SLE patients and 25 controls were included in this study. Clinical and laboratory data of patients at the time of the study were recorded. SLE disease activity and damage were assessed using the SLEDAI-2K disease score and SLICC damage index, respectively. Plasma 25-OH Vit D, IFN-γ, and IL-17 concentrations were determined using the human ELISA kit.

RESULTS

Plasma 25-OH Vit D levels (20 ng/mL) were significantly lower in JO-SLE patients compared to (31 ng/mL) controls (P = 0.014). Plasma levels of IFN-γ and IL-17 were significantly higher (163.5 and 25.5 pg./mL) in JO-SLE patients than (68.3 and 3 pg./mL) that of controls (P = 0.016 and P = 0.013). There was a significant negative correlation between 25-OH Vit D levels and SLEDAI-2K (R= -0.431) as well as IFN-γ (R= -0.471) plasma level (P = 0.022 and P = 0.027).

CONCLUSION

IFN-γ and IL-17 were significantly higher in JO-SLE patients, while 25-OH Vit D was significantly lower compared to controls. There was a negative correlation between 25-OH Vit D and each of SLEDAI-2K and IFN-γ.