Vitamin D: calcium and bone homeostasis during evolution

Unveiling the Metabolic Trajectory of Pig Feces Across Different Ages and Senescence

Porcine models are increasingly recognized for their similarities to humans and have been utilized in disease modeling and organ grafting research. While extensive metabolomics studies have been conducted in swine, primarily focusing on conventional cohorts or specific animal models, the composition and functions of fecal metabolites in pigs across different age groups-particularly in the elderly-remain inadequately understood. In this study, an untargeted metabolomics approach was employed to analyze the fecal metabolomes of pigs at three distinct age stages: young (one year), middle-aged (four years), and elderly (eight years). The objective was to elucidate age-associated changes in metabolite composition and functionality under standardized rearing conditions. The untargeted metabolomic analysis revealed a diverse array of age-related metabolites. Notably, L-methionine sulfoxide levels were found to increase with age, whereas cytidine-5-monophosphate levels exhibited a gradual decline throughout the aging process. These metabolites demonstrated alterations across various biological pathways, including energy metabolism, pyrimidine metabolism, lipid metabolism, and amino acid metabolism. Collectively, the identified key metabolites, such as L-methionine sulfoxide and Cholecalciferol, may serve as potential biomarkers of senescence, providing valuable insights into the mechanistic understanding of aging in pigs.

Vitamin D and Aging: Central Role of Immunocompetence

The pro-hormone vitamin D3 is an important modulator of both innate and adaptive immunity since its biologically active metabolite 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3) regulates via the transcription factor VDR (vitamin D receptor) the epigenome and transcriptome of human immune cells and controls in this way the expression of hundreds of vitamin D target genes. Since the myeloid linage of hematopoiesis is epigenetically programmed by VDR in concert with the pioneer factors PU.1 (purine-rich box 1) and CEBPα (CCAAT/enhancer binding protein α), monocytes, macrophages, and dendritic cells are the most vitamin D-sensitive immune cell types. The central role of the immune system in various aging-related diseases suggests that immunocompetence describes not only the ability of an individual to resist pathogens and parasites but also to contest non-communicative diseases and the process of aging itself. In this review, we argue that the individual-specific responsiveness to vitamin D relates to a person's immunocompetence via the epigenetic programming function of VDR and its ligand 1,25(OH)2D3 during hematopoiesis as well as in the periphery. This may provide a mechanism explaining how vitamin D protects against major common diseases and, in parallel, promotes healthy aging.

Easy to gain but hard to lose: the evolution of the knee sesamoid bones in Primates-a systematic review and phylogenetic meta-analysis

Sesamoids are variably present skeletal elements found in tendons and ligaments near joints. Variability in sesamoid size, location and presence/absence is hypothesized to enable skeletal innovation, yet sesamoids are often ignored. Three knee sesamoids-the cyamella, medial fabella and lateral fabella-are present in primates, but we know little about how they evolved, if they are skeletal innovations, or why they are largely missing from Hominoidea. Our phylogenetic comparative analyses suggest that sesamoid presence/absence is highly phylogenetically structured and contains phylogenetic signal. Models suggest that it is easy to gain but difficult/impossible to lose knee sesamoids and that the fabellae may have similar developmental/evolutionary pathways that are distinct from the cyamella. Sesamoid presence/absence is uncorrelated to the mode of locomotion, suggesting that sesamoid biomechanical function may require information beyond sesamoid presence, such as size and location. Ancestral state reconstructions were largely uninformative but highlighted how reconstructions using parsimony can differ from those that are phylogenetically informed. Interestingly, there may be two ways to evolve fabellae, with humans evolving fabellae differently from most other primates. We hypothesize that the 're-emergence' of the lateral fabella in humans may be correlated with the evolution of a unique developmental pathway, potentially correlated with the evolution of straight-legged, bipedal locomotion.

Genomic signaling of vitamin D

It took several hundred million years of evolution, in order to develop the endocrine vitamin D signaling system, which is formed by a nuclear receptor, the transcription factor VDR (vitamin D receptor), its ligand, the vitamin D3 metabolite 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3) and several metabolizing enzymes and transport proteins. Even within the nuclear receptor superfamily the affinity of VDR for 1,25(OH)2D3 is outstandingly high (KD = 0.1 nM). The activation of VDR by 1,25(OH)2D3 is the core mechanism of genomic signaling of vitamin D3, which results in the modulation of the epigenome at thousands of promoter and enhancer regions as well as finally in the activation or repression of hundreds of target gene transcription. In addition, rapid non-genomic actions of vitamin D are described, which are mechanistically far less understood. The main function of vitamin D is to keep the human body in homeostasis. This implies the control of calcium levels, which is essential for bone mineralization, as well as for pushing of innate immunity to react sufficiently strong to microbe infection and preventing overreactions of adaptive immunity, i.e., not to cause autoimmune diseases. This review will discuss whether genomic signaling is sufficient for explaining all physiological functions of vitamin D3.

Health Effects of Vitamin D Supplementation: Lessons Learned From Randomized Controlled Trials and Mendelian Randomization Studies

Vitamin D plays an important role in calcium homeostasis and many cellular processes. Although vitamin D supplements are widely recommended for community-dwelling adults, definitive data on whether these supplements benefit clinically important skeletal and extraskeletal outcomes have been conflicting. Although observational studies on effects of vitamin D on musculoskeletal and extraskeletal outcomes may be confounded by reverse causation, randomized controlled studies (RCTs) and Mendelian randomization (MR) studies can help to elucidate causation. In this review, we summarize the recent findings from large RCTs and/or MR studies of vitamin D on bone health and risk of fractures, falls, cancer, and cardiovascular disease, disorders of the immune system, multiple sclerosis, and mortality in community-dwelling adults. The primary analyses indicate that vitamin D supplementation does not decrease bone loss, fractures, falls, cancer incidence, hypertension, or cardiovascular risk in generally healthy populations. Large RCTs and meta-analyses suggest an effect of supplemental vitamin D on cancer mortality. The existence of extraskeletal benefits of vitamin D supplementations are best documented for the immune system especially in people with poor vitamin D status, autoimmune diseases, and multiple sclerosis. Accumulating evidence indicates that vitamin D may reduce all-cause mortality. These findings, in mostly vitamin D-replete populations, do not apply to older adults in residential communities or adults with vitamin D deficiency or osteoporosis. The focus of vitamin D supplementation should shift from widespread use in generally healthy populations to targeted vitamin D supplementation in select individuals, good nutritional approaches, and elimination of vitamin D deficiency globally. © 2023 American Society for Bone and Mineral Research (ASBMR).

Molecular cloning, expression analysis and functional characterization of chicken cytochrome P450 27A1: A novel mitochondrial vitamin D3 25-hydroxylase

Vitamin D₃ is hydroxylated by cytochrome P450 (CYP) before exerting biological effects. The chicken CYP involved in vitamin D₃ 25-hydroxylation has yet to be cloned, and little is known about its functional characteristics, tissue distribution, and cellular expression. We identified a novel, full-length CYP27A1 gene cloned from chicken hepatocyte cDNA that encodes a putative protein of 518 amino acids. Swiss modeling revealed that chicken CYP27A1 has a classic open-fold form. Multisequence homology alignment determined that CYP27A1 contains conserved motifs for substrate recognition and binding. Quantitative real-time PCR analysis in 2-mo-old Partridge Shank broilers demonstrated that CYP27A1 mRNA levels were highest in the liver, followed by the thigh muscles, the breast muscles, and kidneys. The transcripts of CYP27A1 in breast muscles were significantly higher in males than in females. A subcellular localization analysis demonstrated that CYP27A1 was mainly expressed in the mitochondria. In vitro enzyme assays suggested that recombinant CYP27A1 hydroxylates vitamin D₃ at the C-25 position to form 25-hydroxyvitamin D₃ (25(OH)D₃). The K_m and V_max values for CYP27A1-dependent vitamin D₃ 25-hydroxylation were estimated to be 4.929 μM and 0.389 mol min^-1 mg^-1 protein, respectively. In summary, these results suggest that CYP27A1 encodes a mitochondrial CYP that plays an important physiologic role in the 25-hydroxylation of vitamin D₃ in chickens, providing novel insights into vitamin D₃ metabolism in this species.

Vitamin D: A master example of nutrigenomics

Nutrigenomics attempts to characterize and integrate the relation between dietary molecules and gene expression on a genome-wide level. One of the biologically active nutritional compounds is vitamin D₃, which activates via its metabolite 1α,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) the nuclear receptor VDR (vitamin D receptor). Vitamin D₃ can be synthesized endogenously in our skin, but since we spend long times indoors and often live at higher latitudes where for many winter months UV-B radiation is too low, it became a true vitamin. The ligand-inducible transcription factor VDR is expressed in the majority of human tissues and cell types, where it modulates the epigenome at thousands of genomic sites. In a tissue-specific fashion this results in the up- and downregulation of primary vitamin D target genes, some of which are involved in attenuating oxidative stress. Vitamin D affects a wide range of physiological functions including the control of metabolism, bone formation and immunity. In this review, we will discuss how the epigenome- and transcriptome-wide effects of 1,25(OH)₂D₃ and its receptor VDR serve as a master example in nutrigenomics. In this context, we will outline the basis of a mechanistic understanding for personalized nutrition with vitamin D₃.

CLCN7, a gene shared by autosomal recessive and autosomal dominant osteopetrosis

After the discovery of abundant v-ATPase complexes in the osteoclast ruffled membrane it was obvious that in parallel a negative counter-ion needs to be transported across this membrane to allow for efficient transport of protons into the resorption lacuna. While different candidate proteins were discussed the osteopetrosis phenotype of Clcn7 knockout mice suggested that the chloride/proton-exchanger ClC-7 might be responsible for transporting the negative charge. In the following, individuals with autosomal recessive osteopetrosis (ARO) were found to carry biallelic CLCN7 pathogenic variants. Shortly thereafter, heterozygous pathogenic variants were identified as the exclusive cause of autosomal dominant osteopetrosis type 2 (ADO2). Since in most cell types other than osteoclasts ClC-7 resides in late endosomes and lysosomes, it took some time until the electrophysiological properties of ClC-7 were elucidated. Whereas most missense variants lead to reduced chloride currents, several variants with accelerated kinetics have been identified. Evidence for folding problems is also known for several missense variants. Paradoxically, a heterozygous activating variant in ClC-7 was described to cause lysosomal alteration, pigmentation defects, and intellectual disability without osteopetrosis. The counter-intuitive 2 Cl^-/H⁺ exchange function of ClC-7 was shown to be physiologically important for intravesicular ion homeostasis. The lysosomal function of ClC-7 is also the reason why individuals with CLCN7-ARO can develop a storage disorder and neurodegeneration, a feature that is variable and difficult to predict. Furthermore, the low penetrance of heterozygous pathogenic CLCN7 variants and the clinical variability of ADO2 are incompletely understood. We aim to give an overview not only of the current knowledge about ClC-7 and its related pathologies, but also of the scientists and clinicians that paved the way for these discoveries.

The role of dietary calcium in the etiology of childhood rickets in the past and the present

For more than two centuries, lack of sunlight has been understood to cause vitamin D deficiency and documented as a primary cause of rickets. As such, evidence of rickets in the archeological record has been used as a proxy for vitamin D status in past individuals and populations. In the last decade, a clinical global consensus has emerged wherein it is recognized that dietary calcium deficiency also plays a role in the manifestation of rickets and classic skeletal deformities may not form if dietary calcium is normal even if vitamin D is deficient. This disease is now clinically called "nutritional rickets" to reflect the fact that rickets can take calcium deficiency-predominant or vitamin D deficiency-predominant forms. However, there are currently no paleopathological studies wherein dietary calcium deficiency is critically considered a primary etiology of the disease. We review here the interplay of calcium, vitamin D, and phosphorous in bone homeostasis, examine the role of dietary calcium in human health, and critically explore the clinical literature on calcium deficiency-predominant rickets. Finally, we report a case of rickets from the late Formative Period (~2500-1500 years ago) of the Atacama Desert and argue the disease in this infant is likely an example of calcium deficiency-predominant rickets. We conclude that most archeological cases of rickets are the result of multiple micronutrient deficiencies that compound to manifest in macroscopic skeletal lesions. For clinicians, these factors are important for implementing best treatment practice, and for paleopathologists they are necessary for appropriate interpretation of health in past communities.

Using SXRF and LA-ICP-TOFMS to Explore Evidence of Treatment and Physiological Responses to Leprosy in Medieval Denmark

Leprosy can lead to blood depletion in Zn, Ca, Mg, and Fe and blood enrichment in Cu. In late medieval Europe, minerals were used to treat leprosy. Here, physiological responses to leprosy and possible evidence of treatment are investigated in enamel, dentine, and cementum of leprosy sufferers from medieval Denmark (n = 12) and early 20th century Romania (n = 2). Using SXRF and LA-ICP-TOFMS, 12 elements were mapped in 15 tooth thin sections, and the statistical covariation of paired elements was computed to assess their biological relevance. The results show marked covariations in the Zn, Ca, and Mg distributions, which are compatible with clinical studies but cannot be directly attributed to leprosy. Minerals used historically as a treatment for leprosy show no detectable intake (As, Hg) or a diffuse distribution (Pb) related to daily ingestion. Intense Pb enrichments indicate acute incorporations of Pb, potentially through the administration of Pb-enriched medication or the mobilization of Pb from bone stores to the bloodstream during intense physiological stress related to leprosy. However, comparisons with a healthy control group are needed to ascertain these interpretations. The positive correlations and the patterns observed between Pb and essential elements may indicate underlying pathophysiological conditions, demonstrating the potential of SXRF and LA-ICP-TOFMS for paleopathological investigations.

Interaction of Vitamin D with Peptide Hormones with Emphasis on Parathyroid Hormone, FGF23, and the Renin-Angiotensin-Aldosterone System

The seminal discoveries that parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23) are major endocrine regulators of vitamin D metabolism led to a significant improvement in our understanding of the pivotal roles of peptide hormones and small proteohormones in the crosstalk between different organs, regulating vitamin D metabolism. The interaction of vitamin D, FGF23 and PTH in the kidney is essential for maintaining mineral homeostasis. The proteohormone FGF23 is mainly secreted from osteoblasts and osteoclasts in the bone. FGF23 acts on proximal renal tubules to decrease production of the active form of vitamin D (1,25(OH)₂D) by downregulating transcription of 1α-hydroxylase (CYP27B1), and by activating transcription of the key enzyme responsible for vitamin D degradation, 24-hydroxylase (CYP24A1). Conversely, the peptide hormone PTH stimulates 1,25(OH)₂D renal production by upregulating the expression of 1α-hydroxylase and downregulating that of 24-hydroxylase. The circulating concentration of 1,25(OH)₂D is a positive regulator of FGF23 secretion in the bone, and a negative regulator of PTH secretion from the parathyroid gland, forming feedback loops between kidney and bone, and between kidney and parathyroid gland, respectively. In recent years, it has become clear that vitamin D signaling has important functions beyond mineral metabolism. Observation of seasonal variations in blood pressure and the subsequent identification of vitamin D receptor (VDR) and 1α-hydroxylase in non-renal tissues such as cardiomyocytes, endothelial and smooth muscle cells, suggested that vitamin D may play a role in maintaining cardiovascular health. Indeed, observational studies in humans have found an association between vitamin D deficiency and hypertension, left ventricular hypertrophy and heart failure, and experimental studies provided strong evidence for a role of vitamin D signaling in the regulation of cardiovascular function. One of the proposed mechanisms of action of vitamin D is that it functions as a negative regulator of the renin-angiotensin-aldosterone system (RAAS). This finding established a novel link between vitamin D and RAAS that was unexplored until then. During recent years, major progress has been made towards a more complete understanding of the mechanisms by which FGF23, PTH, and RAAS regulate vitamin D metabolism, especially at the genomic level. However, there are still major gaps in our knowledge that need to be filled by future research. The purpose of this review is to highlight our current understanding of the molecular mechanisms underlying the interaction between vitamin D, FGF23, PTH, and RAAS, and to discuss the role of these mechanisms in physiology and pathophysiology.

Effect of Serum Level of Vitamin D on External Apical Root Resorption in Maxillary Anterior Teeth in Patients under Fixed Orthodontic Treatment

Introduction

This study aimed to assess the effect of serum level of vitamin D on external apical root resorption (EARR) in maxillary anterior teeth in patients under fixed orthodontic treatment.

Materials and Methods

This retrospective cohort was conducted on patients under fixed orthodontic treatment who were between 12 to 30 years of age. All patients underwent the same treatment technique by the same orthodontist using a 0.022 MBT system. EARR in maxillary anterior teeth was evaluated on pre- and postoperative panoramic radiographs. Blood samples were also collected from patients, and their serum level of vitamin D was measured after the completion of treatment. Data were analyzed by independent t-test and Chi-square test (alpha = 0.05).

Results

A reduction in root length was noted in all patients, which was significant (P < 0.0001); 75% of patients showed EARR in at least one maxillary incisor. EARR had no significant correlation with the serum level of vitamin D (P=0.423).

Conclusions

Serum level of vitamin D had no significant correlation with the occurrence of EARR. However, the high prevalence of EARR calls for measures to minimize it.

Osteoderms as calcium reservoirs: Insights from the lizard Ouroborus cataphractus

The functional significance of osteoderms-bony elements embedded in the dermis-remains a topic of much debate. Although many hypotheses have been put forward in the past, the idea that osteoderms can serve as calcium reservoirs has received little experimental attention thus far. In this study, we use micro-computed tomography to investigate inter- and intrasexual variation in osteoderm density in the viviparous lizard Ouroborus cataphractus and conduct histochemical analyses to unravel the potential mechanism involved in mineral resorption from the osteoderms. Our results show that females have denser, more compact osteoderms than males of similar body sizes, regardless of the season during which they were collected and their reproductive state. Furthermore, a histochemical study demonstrates the presence of mononucleated TRAP-positive cells in the vascular canals of the osteoderms. Based on the findings of this study, we suggest that the mineral storage hypothesis merits further attention as a candidate explanation for osteoderm evolution.

An Update on the Effects of Vitamin D on the Immune System and Autoimmune Diseases

Vitamin D intervenes in calcium and phosphate metabolism and bone homeostasis. Experimental studies have shown that 1,25-dihydroxyvitamin D (calcitriol) generates immunologic activities on the innate and adaptive immune system and endothelial membrane stability. Low levels of serum 25-hydroxyvitamin D (25(OH)D) are associated with an increased risk of developing immune-related diseases such as psoriasis, type 1 diabetes, multiple sclerosis, and autoimmune diseases. Various clinical trials describe the efficacy of supplementation of vitamin D and its metabolites for treating these diseases that result in variable outcomes. Different disease outcomes are observed in treatment with vitamin D as high inter-individual difference is present with complex gene expression in human peripheral blood mononuclear cells. However, it is still not fully known what level of serum 25(OH)D is needed. The current recommendation is to increase vitamin D intake and have enough sunlight exposure to have serum 25(OH)D at a level of 30 ng/mL (75 nmol/L) and better at 40–60 ng/mL (100–150 nmol/L) to obtain the optimal health benefits of vitamin D.

Vitamin D in the Context of Evolution

For at least 1.2 billion years, eukaryotes have been able to synthesize sterols and, therefore, can produce vitamin D when exposed to UV-B. Vitamin D endocrinology was established some 550 million years ago in animals, when the high-affinity nuclear receptor VDR (vitamin D receptor), transport proteins and enzymes for vitamin D metabolism evolved. This enabled vitamin D to regulate, via its target genes, physiological process, the first of which were detoxification and energy metabolism. In this way, vitamin D was enabled to modulate the energy-consuming processes of the innate immune system in its fight against microbes. In the evolving adaptive immune system, vitamin D started to act as a negative regulator of growth, which prevents overboarding reactions of T cells in the context of autoimmune diseases. When, some 400 million years ago, species left the ocean and were exposed to gravitation, vitamin D endocrinology took over the additional role as a major regulator of calcium homeostasis, being important for a stable skeleton. Homo sapiens evolved approximately 300,000 years ago in East Africa and had adapted vitamin D endocrinology to the intensive exposure of the equatorial sun. However, when some 75,000 years ago, when anatomically modern humans started to populate all continents, they also reached regions with seasonally low or no UV-B, i.e., and under these conditions vitamin D became a vitamin.

Vitamin D, the Vitamin D Receptor, Calcitriol Analogues and Their Link with Ocular Diseases

The global prevalence of eye diseases continues to grow, bringing with it a reduction in the activity levels and quality of life of patients, and partial or complete blindness if left untreated. As such, there is considerable interest in identifying more effective therapeutic options and preventive agents. One such agent is vitamin D, known to have a range of anti-cancer, anti-angiogenic, anti-inflammatory and anti-oxidative properties, and whose deficiency is linked to the pathogenesis of a range of cardiovascular, cancer, and inflammatory diseases. This review presents the current stage of knowledge concerning the link between vitamin D and its receptor and the occurrence of eye disease, as well as the influence of analogues of calcitriol, an active metabolite of vitamin D. Generally, patients affected by various ocular disorders have vitamin D deficiency. In addition, previous findings suggest that vitamin D modulates the course of eye diseases and may serve as a marker, and that its supplementation could mitigate some disorders. However, as these studies have some limitations, we recommend further randomized trials to clarify the link between vitamin D and its activity with eye disease.

Novel Insights into the Cardioprotective Effects of Calcitriol in Myocardial Infarction

BACKGROUND

Increasing evidence indicates that vitamin D deficiency negatively affects the cardiovascular system. Here we studied the therapeutic effects of calcitriol in myocardial infarction (MI) and investigated its underlying mechanisms.

METHODS

A MI model of Kun-ming mice induced by left anterior descending coronary artery ligation was utilized to study the potential therapeutic effects of calcitriol on MI. AC16 human cardiomyocyte-like cells treated with TNF-α were used for exploring the mechanisms that underlie the cardioprotective effects of calcitriol.

RESULTS

We observed that calcitriol reversed adverse cardiovascular function and cardiac remodeling in post-MI mice. Mechanistically, calcitriol suppressed MI-induced cardiac inflammation, ameliorated cardiomyocyte death, and promoted cardiomyocyte proliferation. Specifically, calcitriol exerted these cellular effects by upregulating Vitamin D receptor (VDR). Increased VDR directly interacted with p65 and retained p65 in cytoplasm, thereby dampening NF-κB signaling and suppressing inflammation. Moreover, up-regulated VDR was translocated into nuclei where it directly bound to IL-10 gene promoters to activate IL-10 gene transcription, further inhibiting inflammation.

CONCLUSION

We provide new insights into the cellular and molecular mechanisms underlying the cardioprotective effects of calcitriol, and we present comprehensive evidence to support the preventive and therapeutic effects of calcitriol on MI.

Advances in Vitamin D Receptor Function and Evolution Based on the 3D Structure of the Lamprey Ligand-Binding Domain

1α,25-dihydroxyvitamin D3 (1,25D₃) regulates many physiological processes in vertebrates by binding to the vitamin D receptor (VDR). Phylogenetic analysis indicates that jawless fishes are the most basal vertebrates exhibiting a VDR gene. To elucidate the mechanism driving VDR activation during evolution, we determined the crystal structure of the VDR ligand-binding domain (LBD) complex from the basal vertebratePetromyzon marinus, sea lamprey (lVDR). Comparison of three-dimensional crystal structures of the lVDR-1,25D₃ complex with higher vertebrate VDR-1,25D₃ structures suggests that 1,25D₃ binds to lVDR similarly to human VDR, but with unique features for lVDR around linker regions between H11 and H12 and between H9 and H10. These structural differences may contribute to the marked species differences in transcriptional responses. Furthermore, residue co-evolution analysis of VDR across vertebrates identifies amino acid positions in H9 and the large insertion domain VDR LBD specific as correlated.

FGF23 and Vitamin D Metabolism

Apart from its phosphaturic action, the bone-derived hormone fibroblast growth factor-23 (FGF23) is also an essential regulator of vitamin D metabolism. The main target organ of FGF23 is the kidney, where FGF23 suppresses transcription of the key enzyme in vitamin D hormone (1,25(OH)₂D) activation, 1α-hydroxylase, and activates transcription of the key enzyme responsible for vitamin D degradation, 24-hydroxylase, in proximal renal tubules. The circulating concentration of 1,25(OH)₂D is a positive regulator of FGF23 secretion in bone, forming a feedback loop between kidney and bone. The importance of FGF23 as regulator of vitamin D metabolism is underscored by the fact that in the absence of FGF23 signaling, the tight control of renal 1α-hydroxylase fails, resulting in overproduction of 1,25(OH)₂D in mice and men. During recent years, big strides have been made toward a more complete understanding of the mechanisms underlying the FGF23-mediated regulation of vitamin D metabolism, especially at the genomic level. However, there are still major gaps in our knowledge that need to be filled by future research. Importantly, the intracellular signaling cascades downstream of FGF receptors regulating transcription of 1α-hydroxylase and 24-hydroxylase in proximal renal tubules still remain unresolved. The purpose of this review is to highlight our current understanding of the molecular mechanisms underlying the regulation of vitamin D metabolism by FGF23, and to discuss the role of these mechanisms in physiology and pathophysiology. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.

Enhancement of tibia bone and eggshell hardness through the supplementation of bio-calcium derived from fish bone mixed with chelated trace minerals and vitamin D3 in laying duck diet

Cracked eggs cause great economic losses in duck egg production. The use of eggshell-related vitamins and minerals is one of the most suitable approaches for solving this problem. Therefore, this study aimed to evaluate the effects of dietary bio-calcium derived from fish bone mixed with chelated trace minerals and vitamin D3 (BCD) on egg performance, egg quality and the hardness of the tibia bone and the eggshell in laying ducks. A total of eighty 30-week-old Khaki Campbell laying ducks were assigned to 4 groups. Experimental birds were provided a basal diet supplemented with 0.0 (T1), 0.5 (T2), 1.0 (T3), or 2.0 (T4) g/kg BCD. Our results indicated that a negative impact on egg performance was not observed (P > 0.05) in any dietary BCD groups. The different BCD levels had no significant effects on yolk color, yolk ratio, albumen ratio, eggshell ratio or eggshell thickness. Similarly, the calcium and phosphorus contents of the eggshell and tibia bone were not influenced (P > 0.05) by the dietary BCD. Tibia bone weight and length did not differ (P > 0.05) among the 4 treatments. However, tibia bone (P = 0.006) and eggshell hardness (P = 0.025) significantly increased and correlated with increasing BCD levels. The strongest tibia bone and eggshell were found in the 2.0 g/kg BCD group when compared to the control group (P < 0.01). Thus, the study concluded that the inclusion of 2.0 g/kg BCD mixture in laying duck diets can be a potential approach to improve tibia bone and eggshell hardness, without detrimental effect on egg performance.

Vitamin D deficiency promotes accumulation of bioactive lipids and increased endocannabinoid tone in zebrafish

Vitamin D is well known for its traditional role in bone mineral homeostasis; however, recent evidence suggests that vitamin D also plays a significant role in metabolic control. This study served to investigate putative linkages between vitamin D deficiency (VDD) and metabolic disruption of bioactive lipids by MS imaging. Our approach employed infrared-matrix-assisted laser desorption electrospray ionization MS imaging for lipid metabolite profiling in 6-month-old zebrafish fed either a VDD or a vitamin D-sufficient (VDS) diet. Using a lipidomics pipeline, we found that VDD zebrafish had a greater abundance of bioactive lipids (N-acyls, endocannabinoids [ECs], diacylglycerols/triacylglycerols, bile acids/bile alcohols, and vitamin D derivatives) suggestive of increased EC tone compared with VDS zebrafish. Tandem MS was performed on several differentially expressed metabolites with sufficient ion abundances to aid in structural elucidation and provide additional support for MS annotations. To confirm activation of the EC pathways, we subsequently examined expression of genes involved in EC biosynthesis, metabolism, and receptor signaling in adipose tissue and liver from VDD and VDS zebrafish. Gene expression changes were congruent with increased EC tone, with VDD zebrafish demonstrating increased synthesis and metabolism of anandamide compared with VDS zebrafish. Taken together, our data suggest that VDD may promote accumulation of bioactive lipids and increased EC tone in zebrafish.

Vitamin D and the risk for cancer: A molecular analysis

Uncontrolled overgrowth of cells, such as in cancer, is an unavoidable risk in life that affects nearly every second individual in industrialized countries. However, in part this risk can be controlled through lifestyle adjustments, such as the avoidance of smoking, unhealthy diet, obesity, physical inactivity and other cancer risk factors. A low vitaminD status is a risk in particular for cancers of colon, prostate, breast and leukocytes. VitaminD₃ is produced non-enzymatically, when the cholesterol precursor 7-dehydrocholesterol is exposed to UV-B from sunlight, i.e., all cholesterol synthesizing species, including humans, can make vitaminD₃. VitaminD endocrinology started some 550million years ago, when the metabolite 1α,25-dihydroxyvitaminD₃ and the transcription factor vitaminD receptor teamed up for regulating the expression of hundreds of target genes in a multitude of different tissues and cell types. Initially, these genes were focused on the control of energy homeostasis, which later also involved energy-demanding innate and adaptive immunity. Rapidly growing cells of the immune system as well as those of malignant tumors rely on comparable genes and pathways, some of which are modulated by vitaminD. Accordingly, vitaminD has anti-cancer effects both directly via controling the differentiation, proliferation and apoptosis of neoplastic cells as well as indirectly through regulating immune cells that belong to the microenvironment of malignant tumors. This review discusses effects of vitaminD on the epigenome and transcriptome of stromal and tumor cells, inter-individual variations in vitaminD responsiveness and their relation to the prevention and possible therapy of cancer.

Vitamin D Receptor Gene Single Nucleotide Polymorphisms and Association With Vitamin D Levels and Endoscopic Disease Activity in Inflammatory Bowel Disease Patients: A Pilot Study

BACKGROUND

Inflammatory bowel diseases (IBDs) comprise a heterogenous group of chronic gastrointestinal disorders that are multifactorial in etiology. Experimental in vitro and in vivo studies suggest that intestinal vitamin D receptor (VDR) signaling plays a role in modulating the immune response in IBD as a cause and/or a consequence of chronic inflammation.

AIM

The aim of this study is to study the associations between vitamin D receptor gene single nucleotide polymorphisms(SNPs), vitamin D levels, and endoscopic disease activity in IBD.

METHODS

This is a cross-sectional analysis of IBD patients who underwent endoscopic evaluation at a tertiary care hospital. Demographic variables, IBD disease type and location, medical therapies, vitamin D levels, and endoscopic disease activity were collected. Colonic biopsies obtained were investigated for the presence of VDR SNPs: ApaI, TaqI, BsmI, FokI, and Tru9I.

RESULTS

Patients in endoscopic remission had higher vitamin D levels compared with those with inflammation found on endoscopy (P = <0.001). Patients with lower vitamin D levels were homozygous for Fok ancestral alleles (P = 0.0045). With regard to endoscopic disease activity, we found no differences in mutations of any of the VDR SNPs in our sample.

CONCLUSIONS

The association between the presence of the ancestral FokI and lower vitamin D levels suggests a multifactorial etiology for vitamin D deficiency in IBD. Higher vitamin D levels in those in endoscopic remission compared with lower levels in those with active inflammation suggests that the impact of VDR gene SNP on disease activity may be overcome with replacement therapy.

Osteoclasts in Tumor Biology: Metastasis and Epithelial-Mesenchymal-Myeloid Transition

Osteoclast is a specialized cell that originates from monocytic lineage, communicates closely with osteoblasts under physiological conditions, participates in bone modeling and re-modeling, contributes to calcium homeostasis and osteoimmunity. In pathological conditions, it is involved in many tumors such as giant cell bone tumor (osteoclastoma), aneurysmal bone cyst, osteosarcoma, and metastatic cancers, and it usually causes local spread and progression of the tumor, working against the host. Since osteoclasts play an active role in primary bone tumors and bone metastases, the use of anti-osteoclastic agents significantly reduces the mortality and morbidity rates of patients by preventing the progression and local spread of tumors. Osteoclasts also accompany undifferentiated carcinomas of many organs, especially pancreas, thyroid, bladder and ovary. Undifferentiated carcinomas rich in osteoclasts have osteoclastoma-like histology. In these organs, osteoclastoma-like histology may accompany epithelial carcinomas, and de novo, benign and borderline tumors. Mature and immature myeloid cells, including osteoclasts, play an active role in the tumor progression in primary and metastatic tumor microenvironment, in epithelial-mesenchymal transition (EMT), mesenchymal-epithelial-transition (MET), and cancer stem cell formation. Additionally, they are the most suitable candidates for cancer cells in cell fusion due to their evolutionary fusion capabilities. Myeloid features and markers (CD163, CD33, CD68 etc.) can be seen in metastatic cancer cells. Consequently, they provide metastatic cancer cells with motility, margination, transmigration, chemotaxis, phagocytosis, angiogenesis, matrix degradation, and resistance to chemotherapy. For these reasons, we think that the concept of Epithelial-Mesencyhmal-Myeloid-Transition (EMMT) will be more accurate than EMT for cancer cells with myeloid properties.

Modern India and Dietary Calcium Deficiency-Half a Century Nutrition Data-Retrospect-Introspect and the Road Ahead

Calcium and vitamin D are inseparable nutrients required for bone health. In the past half a century, the dietary calcium intake of rural, tribal, and urban India has declined. Though India is the largest producer of milk and cereals, the major source of calcium in India is through non-dairy products. The highest intake of cereals and lowest intake of milk & milk products was observed in rural and tribal subjects whereas, the intake of cereals, milk & milk products were similar in both urban and metropolitan subjects. One of the reasons for lower calcium intake was the proportion of calcium derived from dairy sources. Over the past half a century, the average 30-day consumption of cereals in the rural and urban population has declined by 30%. The Per Capita Cereal Consumption (PCCC)has declined despite sustained raise in Monthly Per capita Consumption Expenditure (MPCE) in both rural and urban households. The cereal consumption was the highest in the lowest income group, despite spending smaller portion of their income, as cereals were supplied through public distribution system (PDS). About 85% of the Indian population are vitamin D deficient despite abundant sunlight. Dietary calcium deficiency can cause secondary vitamin D deficiency. Though India as a nation is the largest producer of milk, there is profound shortage of calcium intake in the diet with all negative consequences on bone health. There is a decline in dietary calcium in the background of upward revision of RDI/RDA. There is a gap in the production-consumption-supply chain with respect to dietary calcium. To achieve a strong bone health across India, it is imperative to have population based strategies addressing different segments including supplementing dietary/supplemental calcium in ICDS, mid-day-meals scheme, public distribution system, educational strategies. Other measures like mass food fortification, biofortification, bioaddition, leveraging digital technologies, investments from corporate sector are some measures which can address this problem. India is a vast country with diverse social, cultural and dietary habits. No single measure can address this problem and requires a multi-pronged strategic approach to tackle the dietary calcium deficiency to achieve strong bone health while solving the problem of nutritional deficiency.

Recommendations on the measurement and the clinical use of vitamin D metabolites and vitamin D binding protein - A position paper from the IFCC Committee on bone metabolism

Vitamin D, an important hormone with a central role in calcium and phosphate homeostasis, is required for bone and muscle development as well as preservation of musculoskeletal function. The most abundant vitamin D metabolite is 25-hydroxyvitamin D [25(OH)D], which is currently considered the best marker to evaluate overall vitamin D status. 25(OH)D is therefore the most commonly measured metabolite in clinical practice. However, several other metabolites, although not broadly measured, are useful in certain clinical situations. Vitamin D and all its metabolites are circulating in blood bound to vitamin D binding protein, (VDBP). This highly polymorphic protein is not only the major transport protein which, along with albumin, binds over 99% of the circulating vitamin D metabolites, but also participates in the transport of the 25(OH)D into the cell via a megalin/cubilin complex. The accurate measurement of 25(OH)D has proved a difficult task. Although a reference method and standardization program are available for 25(OH)D, the other vitamin D metabolites still lack this. Interpretation of results, creation of clinical supplementation, and generation of therapeutic guidelines require not only accurate measurements of vitamin D metabolites, but also the accurate measurements of several other "molecules" related with bone metabolism. IFCC understood this priority and a committee has been established with the task to support and continue the standardization processes of vitamin D metabolites along with other bone-related biomarkers. In this review, we present the position of this IFCC Committee on Bone Metabolism on the latest developments concerning the measurement and standardization of vitamin D metabolites and its binding protein, as well as clinical indications for their measurement and interpretation of the results.

Bone metabolism and evolutionary origin of osteocytes: Novel application of FIB-SEM tomography

Lacunae and canaliculi spaces of osteocytes are remarkably well preserved in fossilized bone and serve as an established proxy for bone cells. The earliest bone in the fossil record is acellular (anosteocytic), followed by cellular (osteocytic) bone in the jawless relatives of jawed vertebrates, the osteostracans, about 400 million years ago. Virtually nothing is known about the physiological pressures that would have initially favored osteocytic over anosteocytic bone. We apply focused ion beam-scanning electron microscopy tomography combined with machine learning for cell detection and segmentation to image fossil cell spaces. Novel three-dimensional high-resolution images reveal areas of low density around osteocyte lacunae and their canaliculi in osteostracan bone. This provides evidence for demineralization that would have occurred in vivo as part of osteocytic osteolysis, a mechanism of mineral homeostasis, supporting the hypothesis that a physiological demand for phosphorus was the principal driver in the initial evolution of osteocytic bone.

Collation of Strontium Concentration Ratios from Water to Aquatic Biota Species in Freshwater and Marine Environments and Factors Affecting the Ratios

The fate of strontium-90 (⁹⁰Sr) from water to aquatic biota is of concern since the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident because of continuous small ⁹⁰Sr releases to the seawater from the FDNPP site. The Japanese diet includes many edible marine and freshwater species, and the environmental parameter, that is, the concentration ratio (CR) from water to biota, is useful to estimate the potential ⁹⁰Sr intake, especially from frequently consumed seafoods. However, widely used CR data for radiation dose assessment only have provided values for biota types such as fish, crustaceans, macroalgae, and so forth, and thus, it is difficult to identify specific data for each species. In this study, therefore, we collated CR data of Sr for aquatic biota by surveying available open data sources from the 1950s to 2019, not only for edible parts but also for whole and inedible parts. In total, we obtained 3800 CR data: 3013 data for marine biota, 28 data for brackish water biota, and 759 data for freshwater biota. The results showed that species-specific CRs may decrease the uncertainties compared to those published in IAEA documents; however, different diets and living areas by species may lead to different uncertainties for different species.

Short-term homeostatic regulation of blood/interstitial fluid Ca2+ concentration by the scales of anadromous sea trout Salmo trutta L. during smoltification and migration

The elasmoid scales of anadromous sea trout Salmo trutta L. represent a significant internal reservoir of Ca²⁺ . Although more is known about long-term remodelling of scales in response to calciotropic challenges encountered during smoltification and migration, very little is known about the contribution made by scales to the short-term, minute-to-minute regulation of Ca²⁺ homeostasis in the extracellular fluid (ECF) during these phases of the life cycle. This gap in the knowledge is partly due to the technical challenges involved in measuring small Ca²⁺ fluxes around the scales of live fish in real time. Here, this study describes exfoliating, mounting and culturing scales and their resident cells from parr, smolt and adult sea trout from a freshwater environment, as well as from adult sea trout caught in sea or brackish water. All the scales were then examined using an extracellular, non-invasive, surface-scanning Ca²⁺ -sensitive microelectrode. The authors quantified the Ca²⁺ fluxes, in the absence of any systemic or local regulators, into and out of scales on both the episquamal and hyposquamal sides under different extracellular calcemic challenges set to mimic a variety of ECF-Ca²⁺ concentrations. Scales from the life-cycle stages as well as from adult fish taken from sea, brackish or fresh water all showed a consistent efflux or influx of Ca²⁺ under hypo- or hypercalcemic conditions, respectively. What were considered to be isocalcemic conditions resulted in minimal flux of Ca²⁺ in either direction, or in the case of adult scales, a consistent but small influx. Indeed, adult scales appeared to display the largest flux densities in either direction. These new data extend the current understanding of the role played by fish scales in the short-term, minute-to-minute homeostatic regulation of ECF-Ca²⁺ concentration, and are similar to those recently reported from zebrafish Danio rerio scales. This suggests that this short-term regulatory response might be a common feature of teleost scales.

The Relationship between Vitamin D Level and Lower Urinary Tract Symptoms in Women

Objectives:

In the literature, the effects of vitamin D on lower urinary tract symptoms (LUTS) have been investigated. Conflicting results have been reported in these studies conducted. LUTS is more common in women. In this study, we aimed to evaluate the relationship between vitamin D and LUTS in female patients using the uroflowmetric method.

Methods:

This retrospective cohort study included 186 female patients who were admitted with LUTS. Demographic characteristics, medical history, calcium (Ca) and vitamin D, including laboratory studies and uroflowmetry results, as maximum urine flow rate (Qmax), average urine flow rate (Qav) and voided volume (V) were recorded. Patients were divided into two groups according to age (18-50 and ≥51) and vitamin D levels (<20 and ≥20). Laboratory parameters and uroflowmetry results were compared between groups.

Results:

Mean age was 56.85±12.95 years. Mean vitamin D level was 21.19±13.93 ng/mL (2.5-83.5). Mean Qmax value was 35.41±12.63, whereas the mean Qav was 19.13±9.89, and the mean V was 446.60±165.08 mL. Vitamin D levels differed according to age groups (p=0.044). No significant difference was observed between groups according to Qmax, Qav and V values (p>0.05). No significant correlation was detected between vitamin D level and Qmax, Qav and V values. However, a negative correlation was detected between serum Ca level and V values (p=0.042) in the low vitamin D group.

Conclusion:

There was no direct relationship between vitamin D levels and LUTS in respect to uroflowmetry. However, we determined that Ca levels affect the uroflowmetry parameter in patients with low vitamin D levels. There is a need for further studies emphasizing serum Ca levels in addition to vitamin D levels in patients with LUTS.

Non-classical effects of vitamin D: Non-bone effects of vitamin D

Our understanding of vitamin D has improved considerably in recent years. The role of vitamin D in preventing osteoporotic fractures is now well-established. However, an important controversy has emerged in the last decade concerning the effects of the active form of vitamin D (1,25-dihydroxy-vitamin D) on tissues other than bone (non-classical effects). The demonstration that the vitamin D receptor (VDR) is ubiquitously, expressed combined with increasing observational data supporting a relationship between the level of 25-hydroxy-vitamin D in the serum and chronic metabolic disorders, cardiovascular disease and neoplasms, have led to its redefinition as a steroid hormone and the proposal of its use in preventing and/or treating those diseases. This article is an update on the different non-bone or non-classical effects of "vitamin-hormone D", and its potential preventive or therapeutic role in certain diseases, however, this review is not exhaustive. The different modalities of substitution or supplementation proposed in France by the Groupe de Recherche et d'Information sur les Ostéoporoses (GRIO) are also summarised.

Synergy of melanin and vitamin-D may play a fundamental role in preventing SARS-CoV-2 infections and halt COVID-19 by inactivating furin protease

Since the birth of Christ, in these 2019 years, the man on earth has never experienced a survival challenge from any acellular protist compared to SARS-CoV-2. No specific drugs yet been approved. The host immunity is the only alternative to prevent and or reduce the infection and mortality rate as well. Here, a novel mechanism of melanin mediated host immunity is proposed having potent biotechnological prospects in health care management of COVID-19. Vitamin D is known to enhance the rate of melanin synthesis; and this may concurrently regulate the expression of furin expression. In silico analyses have revealed that the intermediates of melanin are capable of binding strongly with the active site of furin protease. On the other hand, furin expression is negatively regulated via 1-α-hydroxylase (CYP27B1), that belongs to vitamin-D pathway and controls cellular calcium levels. Here, we have envisaged the availability of biological melanin and elucidated the bio-medical potential. Thus, we propose a possible synergistic application of melanin and the enzyme CYP27B1 (regulates vitamin D biosynthesis) as a novel strategy to prevent viral entry through the inactivation of furin protease and aid in boosting our immunity at the cellular and humoral levels.

Bone Mineral Density in Severely Obese Women: Health Risk and Health Protective Risk Factors in Three Different Bone Sites

Factors associated with bone mineral density (BMD) are poorly known in severely obese individuals i.e., a body mass index (BMI) > 35 kg/m2. The objectives of this study were to describe the bone health profile of severely obese Brazilian women, to identify the health risk and health protective factors for BMD in this group and to assess whether these factors vary according to three different bone sites. BMD was assessed using dual-energy X-ray absorptiometry (DXA). This study analyzed baseline data from 104 women who had an average BMI of 43.7 ± 4.5 kg/m2 and presented the following BMD status: 1.283 ± 0.094 g/cm2 for total body, 1.062 ± 0.159 g/cm2 for vertebral column and 1.195 ± 0.134 g/cm2 for hip. They took part in the "Effect of nutritional intervention and olive oil in severe obesity" randomized clinical trial (DieTBra Trial). The risk factors negatively associated with lower BMD were age ≥50 years for the three bone sites i.e., total body, vertebral column and hip. Smoking for total body BMD (p = 0.045); BMI ≥ 50kg/m2 for vertebral column and hip; menopause for hip; high C-reactive protein (CRP) levels (p = 0.049), insufficient zinc (p = 0.010) and previous fracture for vertebral column (p = 0.007). The protective factors positively associated with BMD were physical activity (≥150 min/week (p = 0.001)) for hip; type 2 diabetes mellitus (DM2) (p < 0.0001) total body and adequate vitamin D levels from food consumption (p = 0.039) for vertebral column. A BMI ≥ 50 kg/m2 was a risk factor for lower BMD. The findings showed that protective and risk factors varied by bone site. The original study is registered with ClinicalTrials.gov. (protocol number: NCT02463435).

Vitamin D Metabolism and Profiling in Veterinary Species

The demand for vitamin D analysis in veterinary species is increasing with the growing knowledge of the extra-skeletal role vitamin D plays in health and disease. The circulating 25-hydroxyvitamin-D (25(OH)D) metabolite is used to assess vitamin D status, and the benefits of analysing other metabolites in the complex vitamin D pathway are being discovered in humans. Profiling of the vitamin D pathway by liquid chromatography tandem mass spectrometry (LC-MS/MS) facilitates simultaneous analysis of multiple metabolites in a single sample and over wide dynamic ranges, and this method is now considered the gold-standard for quantifying vitamin D metabolites. However, very few studies report using LC-MS/MS for the analysis of vitamin D metabolites in veterinary species. Given the complexity of the vitamin D pathway and the similarities in the roles of vitamin D in health and disease between humans and companion animals, there is a clear need to establish a comprehensive, reliable method for veterinary analysis that is comparable to that used in human clinical practice. In this review, we highlight the differences in vitamin D metabolism between veterinary species and the benefits of measuring vitamin D metabolites beyond 25(OH)D. Finally, we discuss the analytical challenges in profiling vitamin D in veterinary species with a focus on LC-MS/MS methods.

Vitamin D and Cardiovascular Disease, with Emphasis on Hypertension, Atherosclerosis, and Heart Failure

Vitamin D deficiency is the most common nutritional deficiency, affecting almost one billion people worldwide. Vitamin D is mostly known for its role in intestinal calcium absorption and bone mineralization. However, the observation of seasonal changes in blood pressure and the subsequent identification of vitamin D receptor (VDR) and 1α-hydroxylase in cardiomyocytes, as well as endothelial and vascular smooth muscle cells, implicated a role of vitamin D in the cardiovascular system. Animal studies provided compelling evidence that vitamin D signaling is essential for cardiovascular integrity, especially for the regulation of vascular tone and as an antifibrotic and antihypertrophic signaling pathway in the heart. In addition, observational studies reported an association between vitamin D deficiency and risk of hypertension, atherosclerosis, and heart failure. However, recent clinical intervention studies failed to prove the causal relationship between vitamin D supplementation and beneficial effects on cardiovascular health. In this review, we aim to highlight our current understanding of the role of vitamin D in the cardiovascular system and to find potential explanations for the large discrepancies between the outcome of experimental studies and clinical intervention trials.

Skin colour and vitamin D: An update

Homo sapiens evolved in East Africa and had dark skin, hair, and eyes, in order to protect against deleterious consequences of intensive UV radiation at equatorial latitudes. Intensive skin pigmentation was thought to bear the risk of inefficient vitamin D3 synthesis in the skin. This initiated the hypothesis that within the past 75 000 years, in which humans migrated to higher latitudes in Asia and Europe, the need for vitamin D3 synthesis served as an evolutionary driver for skin lightening. In this review, we summarize the recent archeogenomic reconstruction of population admixture in Europe and demonstrate that skin lightening happened as late as 5000 years ago through immigration of lighter pigmented populations from western Anatolia and the Russian steppe but not primarily via evolutionary pressure for vitamin D3 synthesis. We show that variations in genes encoding for proteins being responsible for the transport, metabolism and signalling of vitamin D provide alternative mechanisms of adaptation to a life in northern latitudes without suffering from consequences of vitamin D deficiency. This includes hypotheses explaining differences in the vitamin D status and response index of European populations.

Low vitamin D status is associated with obesity but no other cardiovascular risk factors in Chinese children and adolescents

BACKGROUND AND AIMS

Evidence on relationship between vitamin D status and cardiovascular health in childhood remains inconsistent. This study aimed to investigate vitamin D status and its relationship with cardiovascular risk factors in Chinese children and adolescents.

METHODS AND RESULTS

Cross-sectional data were obtained from 2680 children and adolescents aged 7-18 y in Guangzhou, South China. Anthropometric and socioeconomic characters, concentration of serum 25-hydroxyvitamin D [25(OH)D], fasting blood glucose and lipids, as well as information about diet and physical activity were measured and collected. Logistic regression model was adopted to analyze the associations between 25(OH)D levels and cardiovascular risk factors including obesity, high blood pressure, dyslipidemia, hyperglycemia, and metabolic syndrome. Overall, median level of 25(OH)D was 19.74 ng/mL. The prevalence rates of vitamin D deficiency and inadequacy were 7.5% and 44.4%, both of which were highest among adolescents aged 14-18 y (14.5% and 51.6%, respectively). As vitamin D level increased, an upward trend in fasting glucose concentrations was observed in subjects with normal fasting glucose level, but not in subjects with hyperglycemia. Among the assessed cardiovascular risk factors, vitamin D status was only inversely associated with general obesity, and the adjusted odds ratio was 1.95 (95% CI: 1.08-3.49), comparing the lowest 25(OH)D quartile with the highest one.

CONCLUSIONS

Vitamin D deficiency and inadequacy remain a concern among school-aged children and adolescents in Guangzhou, South China, particularly in adolescents aged 14-18 y. However, low vitamin D status was found only associated with general obesity but no other cardiovascular risk factors.

Clinical and Molecular Genetics of Primary Hyperparathyroidism

Calcium homeostasis is maintained by the actions of the parathyroid glands, which release parathyroid hormone into the systemic circulation as necessary to maintain the serum calcium concentration within a tight physiologic range. Excessive secretion of parathyroid hormone from one or more neoplastic parathyroid glands, however, causes the metabolic disease primary hyperparathyroidism (HPT) typically associated with hypercalcemia. Although the majority of cases of HPT are sporadic, it can present in the context of a familial syndrome. Mutations in the tumor suppressor genes discovered by the study of such families are now recognized to be pathogenic for many sporadic parathyroid tumors. Inherited and somatic mutations of proto-oncogenes causing parathyroid neoplasia are also known. Future investigation of somatic changes in parathyroid tumor DNA and the study of kindreds with HPT yet lacking germline mutation in the set of genes known to predispose to HPT represent two avenues likely to unmask additional novel genes relevant to parathyroid neoplasia.

Vitamin D receptor(s): In the nucleus but also at membranes?

The genomic actions of the vitamin D are mediated via its biologically most potent metabolite 1α,25-dihydroxyvitamin D₃ (1,25(OH)₂ D₃ ) and the transcription factor vitamin D receptor (VDR). Activation of VDR by 1,25(OH)₂ D₃ leads to change in the expression of more 1000 genes in various human tissues. Based on (epi)genome, transcriptome and crystal structure data the molecular details of this nuclear vitamin D signalling pathway are well understood. Vitamin D is known for its role on calcium homeostasis and bone formation, but it also modulates energy metabolism, innate and adaptive immunity as well as cellular growth, differentiation and apoptosis. The observation of rapid, non-genomic effects of 1,25(OH)₂ D₃ at cellular membranes and in the cytosol initiated the question, whether there are alternative vitamin D-binding proteins in these cellular compartments. So far, the best candidate is the enzyme PDIA3 (protein disulphide isomerase family A member 3), which is found at various subcellular locations. Furthermore, also VDR seems to play a role in membrane-based responses to vitamin D. In this viewpoint, we will dispute whether these rapid, non-genomic pathways are a meaningful addition to the genome-wide effects of vitamin D.

Vitamin D and stress urinary incontinence in pregnancy: a cross-sectional study

OBJECTIVE

To assess the association between levels of vitamin D and urinary incontinence (UI) in pregnancy.

DESIGN

A cross-sectional study. Secondary analysis of a randomised controlled trial.

SETTING

Two university hospitals in Norway.

POPULATION

A total of 851 healthy, pregnant women >18 years in gestational weeks 18-22 with a singleton live fetus.

METHODS

Data on UI were collected from a questionnaire at inclusion and serum analysis of 25-hydroxy vitamin D (25(OH)D) was performed. Univariable and multivariable logistic regression analyses were applied to study associations between exposure and outcomes.

MAIN OUTCOME MEASURES

Prevalence of self-reported UI, stress (SUI) and urge (UUI) or mixed UI.

RESULTS

In total, 230/851 (27%) of the participants were vitamin D insufficient (25(OH)D <50 nmol/l) and 42% reported to have any UI. Women with 25(OH)D <50 nmol/l were more likely to report any UI (P = 0.03) and SUI (P < 0.01) compared with women with 25(OH)D ≥50 nmol/l. In a univariable logistic regression analysis, serum levels of 25(OH)D <50 nmol/l was associated with increased risk of any UI (odds ratio [OR] 1.5 with 95% CI 1.0-2.1), SUI only (OR 1.7, 95% CI 1.2-2.4), but not mixed UI or UUI only (OR 0.8, 95% CI 0.5-1.5). In a multivariable logistic regression model, serum levels of 25(OH)D <50 nmol/l were associated with a higher risk of experiencing SUI only (OR 1.5, 95% CI 1.1-2.2).

CONCLUSIONS

Serum 25(OH)D <50 nmol/l was associated with increased risk of any UI, and SUI in particular.

TWEETABLE ABSTRACT

Low levels of vitamin D are associated with increased risk of urinary incontinence in pregnancy.

Impact of Epigenetics on Complications of Fanconi Anemia: The Role of Vitamin D-Modulated Immunity

Fanconi anemia (FA) is a rare disorder with the clinical characteristics of (i) specific malformations at birth, (ii) progressive bone marrow failure already during early childhood and (iii) dramatically increased risk of developing cancer in early age, such as acute myeloid leukemia and squamous cell carcinoma. Patients with FA show DNA fragility due to a defect in the DNA repair machinery based on predominately recessive mutations in 23 genes. Interestingly, patients originating from the same family and sharing an identical mutation, frequently show significant differences in their clinical presentation. This implies that epigenetics plays an important role in the manifestation of the disease. The biologically active form of vitamin D, 1α,25-dihydroxyvitamin D₃ controls cellular growth, differentiation and apoptosis via the modulation of the immune system. The nuclear hormone activates the transcription factor vitamin D receptor that affects, via fine-tuning of the epigenome, the transcription of >1000 human genes. In this review, we discuss that changes in the epigenome, in particular in immune cells, may be central for the clinical manifestation of FA. These epigenetic changes can be modulated by vitamin D suggesting that the individual FA patient’s vitamin D status and responsiveness are of critical importance for disease progression.

Key Vitamin D Target Genes with Functions in the Immune System

The biologically active form of vitamin D3, 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3), modulates innate and adaptive immunity via genes regulated by the transcription factor vitamin D receptor (VDR). In order to identify the key vitamin D target genes involved in these processes, transcriptome-wide datasets were compared, which were obtained from a human monocytic cell line (THP-1) and peripheral blood mononuclear cells (PBMCs) treated in vitro by 1,25(OH)2D3, filtered using different approaches, as well as from PBMCs of individuals supplemented with a vitamin D3 bolus. The led to the genes ACVRL1, CAMP, CD14, CD93, CEBPB, FN1, MAPK13, NINJ1, LILRB4, LRRC25, SEMA6B, SRGN, THBD, THEMIS2 and TREM1. Public epigenome- and transcriptome-wide data from THP-1 cells were used to characterize these genes based on the level of their VDR-driven enhancers as well as the level of the dynamics of their mRNA production. Both types of datasets allowed the categorization of the vitamin D target genes into three groups according to their role in (i) acute response to infection, (ii) infection in general and (iii) autoimmunity. In conclusion, 15 genes were identified as major mediators of the action of vitamin D in innate and adaptive immunity and their individual functions are explained based on different gene regulatory scenarios.

Serum calcium, magnesium, phosphorus, and vitamin D in benign essential blepharospasm

PURPOSE

This study aims to compare serum calcium, magnesium, phosphorus, and 25-hydroxy (OH)-vitamin D levels in patients with benign essential blepharospasm (BEB) and healthy subjects and to determine their association with disease severity and frequency.

METHODS

This is a prospective study conducted in a tertiary care hospital. Fifty patients (female, 39; male, 11) with BEB and 22 healthy subjects (female, 15; male, 7) included in the study. Serum calcium, magnesium, phosphorus, and vitamin D levels of BEB and healthy groups were measured. Blepharospasm severity and frequency were assessed using scales ranging from 0 to 4 by following the Jankovic Rating Scale (JRS).

RESULTS

Though there was no significant difference regarding magnesium, phosphorus, and 25(OH)-vitamin D levels between the two groups, serum calcium levels of the BEB group were significantly lower than the control group (9.5 ± 0.4 and 9.9 ± 0.4 mg/dl, respectively; P = 0.002), although in the normal range (9-10.5 mg/dl). In the BEB group, the mean Jankovic severity and frequency scores were 3.29 ± 0.54 and 3.59 ± 0.61, respectively. There was a moderate negative correlation between serum 25(OH)-vitamin D levels and Jankovic severity score (r = - 0.332; P = 0.022).

CONCLUSION

Serum calcium levels of the BEB group were significantly lower than the healthy group. Serum vitamin D levels showed a moderate negative correlation with disease severity. The role of calcium and vitamin D in the evolution of the BEB need further investigation at the cellular and anatomical levels.

Vitamin D status in children with leukemia, its predictors, and association with outcome

BACKGROUND

Children and adolescents with leukemia are potentially at high risk of vitamin D inadequacy, which may have clinical relevance for skeletal morbidity, infections, and cancer outcome. This study aimed to evaluate vitamin D status at the time of diagnosis to investigate its predictors and association with overall survival in children with leukemia.

PROCEDURE

We included all 295 children and adolescents diagnosed with leukemia at our institution between 1990 and 2016 who had available serum sample from the time of diagnosis. We analyzed serum 25-hydroxyvitamin D and parathyroid hormone levels and correlated them with clinical data.

RESULTS

The 25-hydroxyvitamin D level was deficient (< 25 nmol/L), insufficient (25-50 nmol/L), sufficient (50-75 nmol/L), and optimal (> 75 nmol/L) in 6.4%, 26.8%, 39.7%, and 27.1% of the children, respectively. Older age and a more recent time of sampling (calendar year) predicted lower 25-hydroxyvitamin D level. In preschool children (age ≤6 years), lower 25-hydroxyvitamin D level was also associated with acute myeloid leukemia, and a 25-hydroxyvitamin D level < 50 nmol/L was associated with inferior overall survival. In school-aged children (age > 6 years), the 25-hydroxyvitamin D level showed significant seasonal variation.

CONCLUSION

It remains unclear whether vitamin D supplementation in pediatric leukemia patients will improve outcome.

The Influence of Vitamin D on Neurodegeneration and Neurological Disorders: A Rationale for its Physio-pathological Actions

Vitamin D is a steroid hormone implicated in the regulation of neuronal integrity and many brain functions. Its influence, as a nutrient and a hormone, on the physiopathology of the most common neurodegenerative diseases is continuously emphasized by new studies. This review addresses what is currently known about the action of vitamin D on the nervous system and neurodegenerative diseases such as Multiple Sclerosis, Alzheimer's disease, Parkinson's disease and Amyotrophic Lateral Sclerosis. Further vitamin D research is necessary to understand how the action of this "neuroactive" steroid can help to optimize the prevention and treatment of several neurological diseases.

Vitamin D: A Micronutrient Regulating Genes

BACKGROUND

At sufficient sun exposure, humans can synthesize vitamin D3 endogenously in their skin, but today's lifestyle makes the secosteroid a true vitamin that needs to be taken up by diet or supplementation with pills. The vitamin D3 metabolite 1α,25-dihydroxyvitamin D3 acts as a nuclear hormone activating the transcription factor vitamin D receptor (VDR).

METHODS

This review discusses the biological effects of micronutrient vitamin D ranging from calcium homeostasis and bone formation to the modulation of innate and adaptive immunity.

RESULTS

Since normal human diet is sufficient in vitamin D, the need for efficient vitamin D3 synthesis in the skin acts as an evolutionary driver for its lightening during the migration out of Africa towards North. Via activating the VDR, vitamin D has direct effects on the epigenome and the expression of more than 1000 genes in most human tissues and cell types.

CONCLUSIONS

The pleiotropic action of vitamin D in health and disease prevention is explained through complex gene regulatory events of the transcription factor VDR.

Unique Solid Phase Microextraction Sampler Reveals Distinctive Biogeochemical Profiles among Various Deep-Sea Hydrothermal Vents

Current methods for biochemical and biogeochemical analysis of the deep-sea hydrothermal vent ecosystems rely on water sample recovery, or in situ analysis using underwater instruments with limited range of analyte detection and limited sensitivity. Even in cases where large quantities of sample are recovered, labile dissolved organic compounds may not be detected due to time delays between sampling and preservation. Here, we present a novel approach for in situ extraction of organic compounds from hydrothermal vent fluids through a unique solid phase microextraction (SPME) sampler. These samplers were deployed to sample effluent of vents on sulphide chimneys, located on Axial Seamount in the North-East Pacific, in the Urashima field on the southern Mariana back-arc, and at the Hafa Adai site in the central Mariana back-arc. Among the compounds that were extracted, a wide range of unique organic compounds, including labile dissolved organic sulfur compounds, were detected through high-resolution LC-MS/MS, among which were biomarkers of anammox bacteria, fungi, and lower animals. This report is the first to show that SPME can contribute to a broader understanding of deep sea ecology and biogeochemical cycles in hydrothermal vent ecosystems.

The Eurasian lactase persistence variant LCT-13910 C/T is associated with vitamin D levels in individuals living at high latitude, more so than exposure to sunlight

Rapid selection of a genetic variant that confers continuous life-long lactase production in Europeans (LCT-13910 C/T) has been attributed to the advantages of acquiring nutrients from consuming milk without the disadvantages of lactose malabsorption. Individuals with this genetic lactase persistence (LP) variant generally consume more milk and have been shown to have higher levels of serum vitamin D. Vitamin D is the principal regulator of Ca absorption and its synthesis in skin is dependent on UVB exposure. The primary aim of the present study was to compare serum vitamin D concentrations with LP variant and to control for UVB exposure. Data from over 100 000 individuals living in Norway, a country with low UVB exposure, was retrospectively retrieved for comparison of genetic LP variant, serum 25-hydroxyvitamin D (25(OH)D) concentration and the time of year when serum samples were taken. For comparison, a similar analysis was performed with a natural dairy micronutrient, namely vitamin B₁₂. It was found that individuals with the genetic LP variant had considerably higher levels of serum 25(OH)D (P < 2 × 10^-16, Cohen's d = 0·73) but lower levels of vitamin B₁₂ (P < 2 × 10^-16, Cohen's d = 0·11), compared with genetic lactase non-persistent individuals, even when controlled for seasonality, age and sex. The difference in serum 25(OH)D levels did not diminish in summer months, showing the role of vitamin D in LP variant selection in areas of low UVB irradiation. LP variant selection advantage through acquiring another dairy micronutrient, vitamin B₁₂, was not observed.

The Role of Skeletal Muscle in Maintaining Vitamin D Status in Winter

The status of vitamin D is determined mainly by its formation in skin by the photochemical action of solar UVB light (wavelength 290-320 nm) on the precursor 7-dehydrocholesterol. Because of seasonal variation in intensity of solar UV light, vitamin D status falls in winter and rises in summer. It has been presumed that there is no functional store of vitamin D. Thus, to avoid deficiency, a nutritional supply would be required in winter. However, there is now evidence that the main circulating metabolite of vitamin D, 25-hydroxyvitamin D, accumulates in skeletal muscle cells, which provide a functional store during the winter months. The mechanism is mediated by muscle cell uptake of circulating vitamin D-binding protein (DBP) through a megalin-cubilin membrane transport process. DBP then binds to cytoplasmic actin to provide an array of high-affinity binding sites for 25-hydroxyvitamin D [25(OH)D]. The repeated passage of 25(OH)D into and out of muscle cells would account for its long residence time in blood.