Pio Conti^1,, Duraisamy Kempuraj²

Vitamin D is involved not only in bone metabolism with an endocrine function, but is also an important regulator/mediator of the innate and inductive immune system and inflammation. Vitamin D shows an inhibitory effect of Th1 cells, both T and B cells, reduces polarization of Th0 cells to Th1 cells and inhibits the generation of cytokines/chemokines. Vitamin D3 plays a role in cell differentiation, such as Th1, Th2, Th17 and Treg cells, promotes the augmentation of anti-inflammatory cytokines IL-4 and IL-10 and inhibits the generation of IFN gamma released by Th1 cells. Mast cells, which participate in innate and acquired immunity, are involved in allergic reactions. Their products can decrease the ability of Treg cells to produce the immunosuppressant and anti-inflammatory IL-10. Vitamin D increases the expression of the soluble decoy receptor sST2 which is capable of inhibiting inflammatory effects. Treatment with vitamin D3 provokes the reduction of transcription and translation of IFN-gamma IL-12p40 and TNF exerting an anti-inflammatory action. Vitamin D leads to the regulation of Bcl2 and modulation of intracellular kinase pathways p38 and P13K. Moreover, it is involved in the activation of several pathways, including MAPK and cAMP/PKA, and others. The mechanism of anti-inflammatory actions of vitamin D is not yet clear, however, it is assumed that vitamin D3 binds to its receptor and inhibits the macrophage cytotoxicity and the release of vasoactive compounds in mast cells. The benefits of vitamin D are widespread in literature, however, to better understand its effect, more studies are needed.

vitamin D, immunity, inflammation, mast cells, macrophages