Further emergent evidence for the vitamin D endocrine system involvement in autoimmune rheumatic disease risk and prognosis

摘要

Recently, vitamin D has received increased worldwide attention for its involvement in reducing risk for several chronic diseases including many cancers, infectious diseases, type 1 diabetes and notably autoimmune rheumatic diseases. The final active metabolite of vitamin D (1,25(OH)D_3) is considered a steroid hormone for its origin from cholesterol (D-hormone), and like glucocorticoids exerts immunomodulatory activities (figure 1). Pathophysiological investigations confirm that severe hypovitaminosis D, in genetically predisposed subjects, can impair self tolerance and immune responses by compromising the regulation of dendritic cells, regulatory T-lymphocytes (Tregs), Th1 cells and B cell function.3 Cross-sectional studies have shown that deficient serum levels of vitamin D (25(OH)D) (<20ng/ml) are present in a significant percentage, not only in patients with autoimmune diseases such as multiple sclerosis (MS), type 1 diabetes, systemic lupus erythematosus (SLE) or rheumatoid arthritis (RA), but also in healthy subjects. In addition, the presence of severe 25(OH)D deficiency (<10ng/ml) is also involved in the generation of symptoms that characterise patients with rheumatic diseases (ie, musculoskeletal pain in RA), and supplementation seems to induce improvements.