Vitamin D deficiency linked to autoantibodies, SLE development
MedWire News: Low levels of vitamin D may play a role in the production of autoantibodies and the development of systemic lupus erythematosus (SLE), suggest study findings published in the Annals of the Rheumatic Diseases.
"While vitamin D deficiency has been reported in many autoimmune diseases, this is the first observation in anti-nuclear antibody (ANA)-positive healthy individuals," say Judith James (Oklahoma Medical Research Foundation, Oklahoma City, USA) and co-workers.
"This finding is interesting because patients with autoimmune disease, especially those with SLE, possess many risk factors for vitamin D deficiency whereas healthy controls do not. This provides epidemiological evidence to suggest that vitamin D deficiency in autoimmunity is not solely a consequence of lifestyle changes associated with the disease."
The researchers examined levels of 25-hydroxyvitamin D (25(OH)D), ANAs, and serum interferon (IFN)α in 32 European American women with SLE and 32 age-, race-, and gender-matched healthy individuals. Of the controls, 14 were positive for ANAs and 18 were negative.
B cell activation status, known to be modulated by vitamin D, was also determined from levels of intracellular phospho-ERK1/2 in peripheral blood mononuclear cells.
Of note, 25(OH)D deficiency, defined as less than 20 ng/ml, was significantly more common in the SLE patients and the ANA-positive controls than the ANA-negative controls (69% and 71% vs 22%, odds ratio=7.7 and 8.8, respectively).
Vitamin D deficiency was associated with higher mean IFNα activity than adequate levels (3.5 vs 0.3, where elevated is defined as >1). Furthermore, participants with high levels of B cell activation had significantly lower concentrations of 25(OH)D than those with low level activation (17.2 vs 24.2 ng/ml).
"The fact that both ANA-positive healthy individuals and patients with SLE have decreased vitamin D suggests that the mechanism operates early in the steps to SLE development, before the appearance of clinical findings," suggest James et al.
"Beyond considering the molecular mechanisms by which vitamin D deficiency would predispose to autoimmunity, the extraordinarily high prevalence of vitamin D deficiency in ANA-positive healthy individuals and patients with SLE strongly suggests that repletion with vitamin D should be considered."
A longitudinal study could determine whether vitamin D supplements to replenish levels can indeed reduce ANA titers, they conclude.
By Lynda Williams