Back to the future: a new look at ‘old’ vitamin D

Abstract

Our perception of the vitamin D system continues to evolve. Recent studies have re-evaluated the parameters for adequate vitamin D status in humans, revealing a high prevalence of insufficiency in many populations throughout the world. Other reports have highlighted the potential consequences of vitamin D insufficiency beyond established effects on bone homeostasis. Most notably, there is now strong evidence of a role for vitamin D in modulating innate and adaptive immunities, with insufficiency being linked to infectious disease and other immune disorders. To date, signaling pathways for these new responses to vitamin D have been based on established endocrine models for active 1,25-dihydroxyvitamin D, despite present evidence for more localized, intracrine modes of action. In the following review, we provide a fresh perspective on vitamin D signaling in nonclassical target cells such as macrophages by highlighting novel factors associated with the transport and action of this pluripotent secosteroid.

Investigation of the potential association of vitamin D binding protein with lipoproteins

“…First of all, this member of the albumin superfamily of binding proteins is a passive carrier and an active facilitator of the cellular uptake of vitamin D and its metabolites. 1 The large molar excess of DBP in relation to its major ligand 25(OH)-vitamin D 3 opens the possibility to act as a circulating vitamin D reservoir. Besides the well-described variety of DBP phenotypes (three common alleles, together with numerous other variants) and genotypes, little attention has been paid to the association of this plasma protein with the various lipoprotein fractions.…”

Is There Any Impact of VDR Gene Polymorphism in Bataks Ethnic to Have Tuberculosis?

“…As a ligand of vitamin D, VDR could be activated if Vitamin D Receptor form heterodimer with Retinoid X Receptor (RXR) hence binding to Vitamin D Response Elements (VDRE) which are controlled by Vitamin D Response Elements-Binding Protein (VDRE-BP) on the gene target promoter of cathelicidin [5]. Cathelicidin promotes the elimination of Mtb in phagolysosome.…”

“…It is known that before vitamin D enters the macrophage, inactive vitamin D in the blood serum could be bound to vitamin D binding protein (DBP) or stay in a free state. After inactive vitamin D bind to Toll-Like Receptor on macrophage, the CYP27b1 enzyme on mitochondria forms the active state of vitamin D. Consequently, along with heat shock protein 70 (hsc70) and bcl-2 associated athanogene (BAG-1), active vitamin D and its receptor enter the nucleus and forms heterodimer with Retinoid X Receptor (RXR) [5,42]. Therefore, all that occur in transcription of cathelicidin can influence the results of the study.…”

“…Recently, researches are focusing on the Vitamin D Receptor (VDR), which caught the interest as it was shown that the growth of M. tuberculosis is restrained after vitamin D administration [4,5]. This effect is achieved through the binding of vitamin D to VDR located in macrophages, which activates the antimicrobial peptide cathelicidin synthesis [4], and consequently eliminates Mycobacterium tuberculosis in the phagolysosome [5]. This process and therefore the effect of vitamin D might be influenced by polymorphisms in the VDR gene.…”

Vitamin D Insufficiency: What’s New?

“…Пересмотрена точка зрения об оптимальном содер-жании витамина D в сыворотке крови [18]. В течение многих лет полагали, что дефицит витамина D в орга-низме человека имеет место тогда, когда его концен-трация в крови составляет менее 8 нг/мл.…”