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BioMed Research International
Volume 2016, Article ID 1375858, 5 pages
http://dx.doi.org/10.1155/2016/1375858
Review Article

Crosstalk between Vitamin D Metabolism, VDR Signalling, and Innate Immunity

Department of Digestive Diseases, General Hospital, Tianjin Medical University, Tianjin 300052, China

Received 16 May 2016; Accepted 30 May 2016

Academic Editor: Guan Yang

Copyright © 2016 Rui Lin. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The primary function of vitamin D is to regulate calcium homeostasis, which is essential for bone formation and resorption. Although diet is a source of vitamin D, most foods are naturally lacking vitamin D. Vitamin D is also manufactured in the skin through a photolysis process, leading to a process called the “sunshine vitamin.” The active form of vitamin D, 1,25-dihydroxyvitamin D (calcitriol), is biosynthesised in the kidney through the hydroxylation of 25-hydroxycholecalciferol by the CYP27B1 enzyme. It has been found that several immune cells express the vitamin D receptor (VDR) and CYP27B1; of the latter, synthesis is determined by several immune-specific signals. The realisation that vitamin D employs several molecular mechanisms to regulate innate immune responses is more recent. Furthermore, evidence collected from intervention studies indicates that vitamin D supplements may boost clinical responses to infections. This review considers the current knowledge of how immune signals regulate vitamin D metabolism and how innate immune system function is modulated by ligand-bound VDR.