Background: Vitamin D is a pivotal factor in calcium homeostasis and exerts immunomodulatory effects. Hypovitamin D has been demonstrated in systemic sclerosis (SSc) patients and may be related to more severe disease of longer duration and with extensive skin involvement. 

Objectives: To seek anti-vitamin D antibodies in SSc patients, as found by previous research in patients with systemic lupus erythematosus (SLE).

Methods: The study included 54 SSc patients and 41 volunteers. Immunoglobulin (Ig) G and IgM autoantibody levels against 25(OH)D and 1,25(OH)D were obtained from patients and controls and compared. SSc patients were assessed for autoantibody profile and disease severity. 

Results: Vitamin D antibodies were present in 87% of SSc patients and 42% of controls. Higher levels of anti-25(OH)D IgM antibodies were detected in SSc patients compared to controls (0.48 ± 0.22 vs. 0.29 ± 0.29, respectively, P = 0.002); however, IgG levels were lower in the SSc patients. No such discriminative effect was found regarding anti-1,25(OH)D antibodies between SSc and controls. No correlation was found between vitamin D antibodies and other autoantibodies, disease severity, or target organ damage.

Conclusions: To the best of our knowledge, this is the first study of these novel anti-vitamin D antibodies in SSc patients and the first time a correlation between IgM 25(OH) vitamin D antibodies and scleroderma has been identified. Further research on the pathophysiological significance and therapeutic potential of vitamin D is required.