Vitamin D and systemic lupus erythematous: a review of immunological and clinical aspects.

OBJECTIVES To review the relationships between vitamin D status and systemic lupus erythematosus (SLE) concerning immunological, clinical aspects and possible effects of supplementation in disease modulation. METHODS The literature was reviewed up to January 2017 for studies regarding the epidemiology, pathogenesis, immunological aspects, clinical implications and supplementation strategies. The focus was mainly on studies with implications on every day clinical practice. RESULTS Vitamin D interacts with immune system mechanisms, therefore, it may be involved in the pathogenesis of autoimmune diseases. The literature is concordant on vitamin D insufficiency being endemic in SLE patients. Data on the correlation between SLE disease activity and circulating levels of vitamin D are controversial, as well as those related to the immunomodulatory effects of vitamin D supplementation. Novel areas of study are the relationship between constitutional symptoms and cognitive involvement of SLE and hypovitaminosis D, and the possible role of vitamin D in the formation of the atherosclerotic plaque, opening new avenues for the modulation of the cardiovascular risk. CONCLUSIONS Future studies are needed to fully understand the relationship between hypovitaminosis D and different aspects of SLE. The most challenging topic will be to clarify supplementation strategies with vitamin D analogues that can be effective in modulating disease activity.