Article Text
Abstract
Objectives Vitamin D deficiency is widespread and has been associated with many chronic diseases, including autoimmune disorders. A study was undertaken to explore the impact of low vitamin D levels on autoantibody production in healthy individuals, as well as B cell hyperactivity and interferon α (IFNα) activity in patients with systemic lupus erythematosus (SLE).
Methods Serum samples from 32 European American female patients with SLE and 32 matched controls were tested for 25-hydroxyvitamin D (25(OH)D) levels, lupus-associated autoantibodies and serum IFNα activity. Isolated peripheral blood mononuclear cells were tested for intracellular phospho-ERK 1/2 as a measure of B cell activation status.
Results Vitamin D deficiency (25(OH)D <20 ng/ml) was significantly more frequent among patients with SLE (n=32, 69%) and antinuclear antibody (ANA)-positive controls (n=14, 71%) compared with ANA-negative controls (n=18, 22%) (OR 7.7, 95% CI 2.0 to 29.4, p=0.003 and OR 8.8, 95% CI 1.8 to 43.6, p=0.011, respectively). Patients with high B cell activation had lower mean (SD) 25(OH)D levels than patients with low B cell activation (17.2 (5.1) vs 24.2 (3.9) ng/ml; p=0.009). Patients with vitamin D deficiency also had higher mean (SD) serum IFNα activity than patients without vitamin D deficiency (3.5 (6.6) vs 0.3 (0.3); p=0.02).
Conclusions The observation that ANA-positive healthy controls are significantly more likely to be deficient in vitamin D than ANA-negative healthy controls, together with the finding that vitamin D deficiency is associated with certain immune abnormalities in SLE, suggests that vitamin D plays an important role in autoantibody production and SLE pathogenesis.
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Footnotes
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Funding This work was supported by the National Institutes of Health (NIAID: HHSN266200500026C, AR058554, RR015577, AI082714, AI24717, AR24260, AI083194, AR052364 and AR053483), Kirkland Scholar Award Program at The Hospital for Special Surgery in New York City which is funded exclusively by Rheuminations, Inc., a non-profit foundation dedicated to supporting research leading to the treatment and cure of lupus, OMRF J Donald Capra Fellowship Support, US Department of Veteran Affairs and the OMRF Lou C Kerr Chair in Biomedical Research.
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Competing interests JBH has served as a consultant for BioRad and owns stock in IVAX Diagnostics. All other authors have no competing interest.
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Ethics approval This study was conducted with the approval of the Oklahoma Medical Research Foundation (OMRF) and the University of Oklahoma Health Sciences Center.
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Provenance and peer review Not commissioned; externally peer reviewed.