Vitamin D in autoimmune rheumatic diseases: A view inside gender differences.

A large body of evidence highlights the role for vitamin D deficiency/insufficiency in rheumatic diseases, a group of different pathologies mostly of autoimmune origin. Vitamin D and vitamin D receptor agonists exquisitely modulate the immune system against over-reactivity towards tolerance; on this basis, vitamin D could be a good therapeutic candidate to control autoimmune processes in rheumatic diseases. Similarly, to other autoimmune pathologies, rheumatic diseases show a significant female bias. This sexual dimorphism seems, in part, to rely on the different sex hormone-induced regulation on male and female immune systems. Females, in fact, retain greater immune reactivity and competence likely due to estrogens, which, at variance with androgens, are associated with a greater resilience to infections but also to a higher risk for autoimmunity. In this scenario, there is growing interest on vitamin D supplementation for prevention or therapy in rheumatic diseases in relation to gender and sexual hormones. The purpose of the review is to overview vitamin D status in rheumatic diseases, related to gender and sex hormones. In particular, the main vitamin D immunoregulatory properties are summarized with some sex hormone-driven immune activities, in females and males immune systems. Topics onto vitamin D receptor agonists as potential therapeutic agents in rheumatic disease are addressed, especially in view of the role of vitamin D inadequacy in the pathogenesis of rheumatic diseases. So far, further clinical and basic studies should be encouraged to confirm the high potential power of vitamin D receptor agonists as novel pharmacological tools in rheumatic diseases particularly in light of personalized gender-related therapeutic strategies.