Immunomodulatory effects of vitamin D and their mechanisms

For many years, researchers have focused their attention on vitamin D preparations. This interest is explained by the vitamin’s unique biological properties and its specific metabolic transformation in the human body, resulting in the formation of hormone-like compounds capable of influencing gene activity and regulating intracellular functions and metabolic processes. This review analyzes published data on vitamin D vitamers and the potential mechanisms underlying their biological effects. The article presents a detailed description of the metabolic transformation of vitamin D (cholecalciferol and ergocalciferol) and characterizes its major metabolites. The mechanisms mediating the biological effects of calcitriol—the primary active metabolite of vitamin D—are discussed. Its final genomic and nongenomic effects on cells are described. Particular attention is given to the influence of vitamin D on the immune system. Vitamin D’s immunomodulatory effects and the potential mechanisms underlying these effects are discussed. The analysis demonstrates that vitamin D is a critical regulator of immune response. Its immunomodulatory effects are mediated both via cellular genetic mechanisms and by influencing intracellular metabolic processes. The active metabolite of vitamin D affects both the cellular and humoral components of innate immunity, as well as the division, proliferation, and differentiation of T and B lymphocytes, and the levels of various cytokines. The presented findings expand the understanding of the pharmacodynamics of vitamin D preparations and highlight their potential use in the treatment of infectious and autoimmune diseases.