About this Research Topic
Classified as a vitamin and a pre-hormone, vitamin D, in its biologically active form (calcitriol, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]) is able to immunomodulate the functional activities of both innate and adaptive immune cells. It has been shown to have an effect on B-cells, T-cells, antigen-presenting cells (APCs), neutrophils, and platelets, as these cells express the vitamin D receptor (VDR), a nuclear receptor (NR) and ligand-inducible transcription factor. Humans and some animals have the ability to synthesize vitamin D in the form of previtamin D3 in the skin as a result of localized conversion of 7-dehydrocholesterol (7-DHC) upon exposure to solar ultraviolet B radiation (UVB, 290-320 nm). Previtamin D3 isomerizes in the skin in a heat-sensitive manner to vitamin D3 (cholecalciferol), which undergoes subsequent metabolism in the liver to calcifediol/calcidiol ([25(OH)D3]), and then - mainly in the kidneys – it is metabolized to calcitriol. Many of the enzymes required to metabolize vitamin D are present in various immune cells.
Vitamin D deficiency may lead to increased risk of developing numerous immune-related diseases. This phenomenon appears to be widespread in many geographic locations, and can be considered as a global public health problem in all age groups. Two bioequivalent forms of vitamin D are recommended as vitamin D supplements to correct such a deficiency. These are vitamin D2 (ergocalciferol) obtained from dietary vegetable sources or oral supplements, and vitamin D3, which is found in plants and animals, such as fatty fish, and oral supplements. Vitamin D may also be subjected to nutritional immunomodulation intervention, given it’s role under different conditions, including protection against infections, allergies, autoimmune diseases, and the development of malignant tumors. Vitamin D can also modulate the expression levels and functions of tight junction (TJ) proteins, which can be affected by pathogens. Therefore, it improves various intestinal epithelial junctions and immune barrier integrity, as well as prevents translocation of microbiota from the intestinal epithelium into the circulation and pathological mucosal immune responses towards commensal microbial antigens.
The purpose of this Research Topic is to collect articles on immunomodulatory effects of vitamin D and its potential immune preventative and immunotherapeutic roles in the context of infection, allergy, autoimmunity and cancer, and other inflammation-related diseases. It will also be focused on the immunotherapeutic approaches suggested when vitamin D supplementation is not recommended in the presence of intrinsic factors that may affect its transformation into bioactive form, and therefore alter its immunomodulatory effects.
In this Research Topic, we welcome high-quality Original Research, Clinical Trial, Case Report, Review, Systematic Review, and Opinion articles exploring vitamin D immunomodulatory nutritional intervention.
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