Not only calcium and bone homeostasis: Vitamin D in auto-immune diseases

F. Pandolfi, L. Franza, S. Altamura and V. Carusi

Department of Clinical Medicine, Clinical immunology Unit, Fondazione Policlinico Universitario A. Gemelli IRCCS – Università Cattolica del Sacro Cuore, Roma, Italy

     Vitamin D plays an important role in calcium regulation and bone homeostasis. In recent years, it has been discovered that its role goes beyond this: vitamin D has potent immune-modulating effects.
For instance, vitamin D and its receptor (vitamin D receptor, VDR) play an important role in various forms of cancer. In particular, metastatic potential and tumor progression appear to be influenced by VDR signaling, whereas vitamin D serum levels have shown to have an inverse correlation with the risk of developing different types of cancer. The role of vitamin D in cancer come down to its immune-modulating effects, which play an extremely interesting effect on auto-immune diseases (1).
When considering rheumatologic disease such as rheumatoid arthritis (RA), the role of vitamin D may be twice as interesting, as its effect on calcium and bone homeostasis may add up to its direct immunologic effects (2).
In this paper, we will address the role of vitamin D in autoimmune diseases; 25(OH)D3 serum levels, vitamin D intake, UV exposure and VDR polymorphisms are all linked to the correct functioning of the immune system. Furthermore, vitamin D has shown to have the potential to suppresses auto-immune disease in experimental models.
Finally, clinical practice has shown that vitamin D supplementation exerts positive effects on several autoimmune diseases such as multiple sclerosis (MS), RA, Chron’s disease (CD), diabetes mellitus (DM) and systemic lupus erythematosus (SLE).

1. Pandolfi F, Franza L, Mandolini C, Conti P. Immune Modulation by Vitamin D: Special Emphasis on Its Role in Prevention and Treatment of Cancer. Clinical therapeutics. 2017;39(5):884-93.
2. Ishikawa LLW, Colavite PM, Fraga-Silva TFC, Mimura LAN, Franca TGD, Zorzella-Pezavento SFG, et al. Vitamin D Deficiency and Rheumatoid Arthritis. Clinical reviews in allergy & immunology. 2017;52(3):373-88.