Vitamin D in active systemic lupus erythematosus and lupus nephritis: a forgotten player

Abstract

Abstract Background Systemic lupus erythematosus (SLE) is an autoimmune disorder associated with immunological abnormalities (Aringer et al., Arthritis Rheumatol 71:1400-1412, 2019). Vitamin D (VD) has an important role in SLE pathogenesis, as it controls cell cycle progression besides its anti-proliferative effects (Liu et al., J Cell Commun Signal 71, 2019). Determining the relationship between VD with SLE activity and lupus nephritis (LN) can establish a new role for VD in SLE management (Liu et al., J Cell Commun Signal 71, 2019). In our study, we aimed to assess the relationship between levels of VD in patients with SLE activity and with LN and to verify the relationship between VD levels with clinical and laboratory parameters in those patients, in order to assess the validity of adding serum VD level in the routine follow-up as a marker that may lead to earlier diagnosis of SLE activity and LN in adult SLE patients. Results Serum VD was significantly lower in SLE patients (3.38 ± 2.55 ng/ml) versus healthy controls (5.36 ± 2.88 ng/ml) (P < 0.002). Interestingly, serum VD was significantly lower in patient with active SLE according to SLEDAI (3.00 ± 2.27 ng/ml) versus those with inactive SLE (5.10 ± 3.19 ng/ml) (P < 0.02). Significant negative correlation was found between serum level of VD and each of mucocutaneous, malar rash, and renal manifestations. Significant negative correlation was also noticed among SLEDAI (P value = 0.01) and renal SLEDAI scores (P value = 0.021) with serum level of VD. Conclusion Low levels of VD were found to be frequent in SLE patients especially during phases of SLE activity and nephritis. Potent markers of low serum VD level in SLE patients were found to be mucocutaneous, malar rash, and LN. Our results support that VD levels could act as independent risk factors for activity and LN in SLE patients; moreover, treatment with VD supplementation could decrease the incidence of activity and nephritis in SLE patients.