The nuclear vitamin D receptor controls the expression of genes encoding factors which feed the "Fountain of Youth" to mediate healthful aging

Multiomics profiling reveals VDR as a central regulator of mesenchymal stem cell senescence with a known association with osteoporosis after high-fat diet exposure

The consumption of a high-fat diet (HFD) has been linked to osteoporosis and an increased risk of fragility fractures. However, the specific mechanisms of HFD-induced osteoporosis are not fully understood. Our study shows that exposure to an HFD induces premature senescence in bone marrow mesenchymal stem cells (BMSCs), diminishing their proliferation and osteogenic capability, and thereby contributes to osteoporosis. Transcriptomic and chromatin accessibility analyses revealed the decreased chromatin accessibility of vitamin D receptor (VDR)-binding sequences and decreased VDR signaling in BMSCs from HFD-fed mice, suggesting that VDR is a key regulator of BMSC senescence. Notably, the administration of a VDR activator to HFD-fed mice rescued BMSC senescence and significantly improved osteogenesis, bone mass, and other bone parameters. Mechanistically, VDR activation reduced BMSC senescence by decreasing intracellular reactive oxygen species (ROS) levels and preserving mitochondrial function. Our findings not only elucidate the mechanisms by which an HFD induces BMSC senescence and associated osteoporosis but also offer new insights into treating HFD-induced osteoporosis by targeting the VDR-superoxide dismutase 2 (SOD2)-ROS axis.

The Vitamin D Metabolite Diagnostic Ratio Associates With Phenotypic Traits of Idiopathic Hypercalciuria

Introduction

Underlying mechanisms for hypercalciuria remain unknown in most cases; thus, the designation "idiopathic." We hypothesized that the vitamin D-inactivating enzyme, CYP24A1 contributes to the pathogenesis of hypercalciuria in kidney stone formers.

Methods

We conducted association analyses between CYP24A1 activity, estimated by the vitamin D metabolite diagnostic ratio (25(OH) vitamin D3/total 24,25 (OH)2 vitamin D ratio; VMDR), and the phenotype of participants in 2 observational cohorts of kidney stone formers, the Swiss Kidney Stone Cohort (SKSC) and the Bern Kidney Stone Registry (BKSR). Circulating 25(OH)- and 24,25 (OH)2 vitamin D were quantified using a validated liquid chromatography tandem mass spectrometry assay.

Results

A total of 974 participants were included in the analysis. We found a positive association of VMDR (and hence negative association of CYP24A1 activity) with total (β 0.009 mmol/l; 95% confidence interval [CI]: 0.002, 0.016; P = 0.02) and ionized plasma calcium (β 0.005 mmol/l; 95% CI: 0.002, 0.008; P < 0.01), absolute and fractional excretion of urinary calcium (β 0.054 mmol/24h; 95% CI: 0.010, 0.097; P = 0.02 and β 0.046%; 95% CI: 0.018, 0.074; P < 0.01, respectively). Further, VMDR was associated with an increased likelihood of forming calcium oxalate dihydrate stones (Odds ratio [OR] 1.64; 95% CI: 1.22, 2.35; P < 0.01) and reduced bone mineral density (BMD) at the femoral neck (β -0.005 g/cm2; 95% CI: -0.010, -0.001; P = 0.04). The described associations became stronger when the analysis was confined to idiopathic calcium stone formers.

Conclusion

Our study reveals that CYP24A1 activity, estimated by VMDR, is associated with clinical traits previously linked to idiopathic hypercalciuria.

Interaction between Fokl polymorphism and vitamin D deficiency in the symptoms of mental disorders in adults: a population-based study

Mental disorders are intricate and multifaceted and encompass social, economic, environmental, and biological factors. This study aimed to explore the potential association between vitamin D deficiency and anxiety and depression symptoms in adults, considering the role of the vitamin D receptor gene polymorphism FokI (rs2228570). This was a population-based cross-sectional study with stratified and cluster sampling, evaluating anxiety symptoms (AS) and depression symptoms (DS) in 1637 adults. Vitamin D levels were measured using electrochemiluminescence and were considered deficient when < 20 ng/mL in a healthy population or < 30 ng/mL in at-risk groups. Genotyping was performed using real-time polymerase chain reaction with TaqMan probes. The prevalence rates of AS, DS, and vitamin D deficiency were 23.5%, 15.8%, and 30.9%, respectively. No direct association was observed between vitamin D deficiency and AS or DS. However, interaction analysis revealed a combined effect of vitamin D deficiency and FokI for DS but not for AS. Individuals with vitamin deficiency and one or two copies of the altered allele of the FokI exhibited a higher prevalence of DS than individuals homozygous for the wild-type allele and vitamin D sufficiency. The interaction between vitamin D deficiency and the FokI polymorphism was associated with DS.

Tremendous Fidelity of Vitamin D3 in Age-related Neurological Disorders

Vitamin D3 (VD) is a secosteroid hormone and shows a pleiotropic effect in brain-related disorders where it regulates redox imbalance, inflammation, apoptosis, energy production, and growth factor synthesis. Vitamin D3's active metabolic form, 1,25-dihydroxy Vitamin D3 (1,25(OH)2D3 or calcitriol), is a known regulator of several genes involved in neuroplasticity, neuroprotection, neurotropism, and neuroinflammation. Multiple studies suggest that VD deficiency can be proposed as a risk factor for the development of several age-related neurological disorders. The evidence for low serum levels of 25-hydroxy Vitamin D3 (25(OH)D3 or calcidiol), the major circulating form of VD, is associated with an increased risk of Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), dementia, and cognitive impairment. Despite decades of evidence on low VD association with neurological disorders, the precise molecular mechanism behind its beneficial effect remains controversial. Here, we will be delving into the neurobiological importance of VD and discuss its benefits in different neuropsychiatric disorders. The focus will be on AD, PD, and HD as they share some common clinical, pathological, and epidemiological features. The central focus will be on the different attributes of VD in the aspect of its anti-oxidative, anti-inflammatory, anti-apoptotic, anti-cholinesterase activity, and psychotropic effect in different neurodegenerative diseases.

Identification of common factors among fibrosarcoma, rhabdomyosarcoma, and osteosarcoma by network analysis

Sarcoma cancers are uncommon malignant tumors, and there are many subgroups, including fibrosarcoma (FS), which mainly affects middle-aged and older adults in deep soft tissues. Rhabdomyosarcoma (RMS), on the other hand, is the most common soft-tissue sarcoma in children and is located in the head and neck area. Osteosarcomas (OS) is the predominant form of primary bone cancer among young adults, primarily resulting from sporadically random mutations. This frequently results in the dissemination of cancer cells to the lungs, commonly known as metastasis. Mesodermal cells are the origin of sarcoma cancers. In this study, a rather radical approach has been applied. Instead of comparing homogenous cancer types, we focus on three main subtypes of sarcoma: fibrosarcoma, rhabdomyosarcoma, and osteosarcoma, and compare their gene expression with normal cell groups to identify the differentially expressed genes (DEGs). Next, by applying protein-protein interaction (PPI) network analysis, we determine the hub genes and crucial factors, such as transcription factors (TFs), affected by these types of cancer. Our findings indicate a modification in a range of pathways associated with cell cycle, extracellular matrix, and DNA repair in these three malignancies. Results showed that fibrosarcoma (FS), rhabdomyosarcoma (RMS), and osteosarcoma (OS) had 653, 1270, and 2823 differentially expressed genes (DEGs), respectively. Interestingly, there were 24 DEGs common to all three types. Network analysis showed that the fibrosarcoma network had two sub-networks identified in FS that contributed to the catabolic process of collagen via the G-protein coupled receptor signaling pathway. The rhabdomyosarcoma network included nine sub-networks associated with cell division, extracellular matrix organization, mRNA splicing via spliceosome, and others. The osteosarcoma network has 13 sub-networks, including mRNA splicing, sister chromatid cohesion, DNA repair, etc. In conclusion, the common DEGs identified in this study have been shown to play significant and multiple roles in various other cancers based on the literature review, indicating their significance.

Vitamin D receptor rs3782905 and vitamin D binding protein rs7041 polymorphisms are associated with hepatocellular carcinoma susceptibility in cirrhotic HCV patients

BACKGROUND

The severity of chronic hepatitis C and susceptibility to hepatocellular carcinoma (HCC) are associated with genetic variations within vitamin D receptor (VDR) in several populations. This study aims to determine the significance of the VDRs (rs2228570, rs3782905, rs11568820) and DBP (rs7041) for the susceptibility to HCC in Egyptian patients with chronic HCV infection and their effect on the progression of liver cirrhosis to carcinogenesis.

METHODS

Single nucleotide polymorphisms (SNPs) VDR (rs2228570, rs3782905), and DBP rs7041 were genotyped using restriction fragment length-PCR (RFLP-PCR) technique and VDR rs11568820 was genotyped using single strand polymorphism PCR (SSP PCR). These SNPs genotypes, haplotypes and linkage disequilibrium analyses were examined in 299 Egyptian individuals (100 HCV-cirrhotic patients, 99 HCC- HCV patients, and 100 healthy controls).

RESULT

The VDR rs2228570 CC genotype, VDR rs3782905 GC and CC genotypes, and DBP rs7041 GG genotype are significantly higher in HCC. It is noteworthy that, VDR rs3782905 CC and DBP rs7041 TG genotypes are higher in HCV induced liver cirrhosis than with HCC progression in HCV infected patients. Furthermore, among patients, the relationship between these SNPs and smoking status, gender, and HCC susceptibility was reported.

CONCLUSION

Among the four investigated SNPs, there are associations between VDR rs3782905 and DBP rs7041 and the HCC progression in Egyptian patients chronically infected with HCV. These SNPs are considered as risk factors in HCV induced liver cirrhosis and HCC. The combinations of these SNPs with smoking status and gender are statistically linked to a high risk of HCC. Future research with a larger sample size of subjects with HCV infection is advised, because chronic liver disease induced by HCV infection is the primary cause of HCC in Egypt. We recommend screening of these SNPs for prediction of LC and HCC development in HCV infected patients, which may improve the used therapeutic protocol. These results suggest that VDR polymorphisms may be potential determinants for HCC susceptibility in Egyptian HCV patients.

Modulation of the vitamin D/vitamin D receptor system in osteoporosis pathogenesis: insights and therapeutic approaches

Osteoporosis is a prevalent bone disorder characterized by low bone mineral density (BMD) and deteriorated bone microarchitecture, leading to an increased risk of fractures. Vitamin D (VD), an essential nutrient for skeletal health, plays a vital role in maintaining bone homeostasis. The biological effects of VD are primarily mediated through the vitamin D receptor (VDR), a nuclear receptor that regulates the transcription of target genes involved in calcium and phosphate metabolism, bone mineralization, and bone remodeling. In this review article, we conduct a thorough literature search of the PubMed and EMBASE databases, spanning from January 2000 to September 2023. Utilizing the keywords "vitamin D," "vitamin D receptor," "osteoporosis," and "therapy," we aim to provide an exhaustive overview of the role of the VD/VDR system in osteoporosis pathogenesis, highlighting the most recent findings in this field. We explore the molecular mechanisms underlying VDR's effects on bone cells, including osteoblasts and osteoclasts, and discuss the impact of VDR polymorphisms on BMD and fracture risk. Additionally, we examine the interplay between VDR and other factors, such as hormonal regulation, genetic variants, and epigenetic modifications, that contribute to osteoporosis susceptibility. The therapeutic implications of targeting the VDR pathway for osteoporosis management are also discussed. By bringing together these diverse aspects, this review enhances our understanding of the VD/VDR system's critical role in the pathogenesis of osteoporosis and highlights its significance as a potential therapeutic target.

Osteoporosis and dermatoporosis: a review on the role of vitamin D

Osteoporosis (OP) and Dermatoporosis (DP) are expressions of the aging process at the skin and bone levels, respectively. Both conditions are associated with increased morbidity for elderly people, and this requires necessary interventions. They share many common risk factors; among these, vitamin D (VD) deficiency appears to have a role. VD is involved in either disease with many mechanisms, among which immunomodulation. VD deficiency has been linked to OP because it inhibits the body's capacity to absorb calcium and maintain optimal bone health. Available evidence suggests that proper vitaminosis D also appears to be vital in preventing skin age-related issues. DP is often seen in elderly individuals, particularly those with long-term sun exposure and a history of chronic sun damage. VD deficiency can be linked to DP, since its involvement in collagen production, epidermal barrier function, inflammation regulation, wound healing, and sun protection. Aim of this review is to summarize the most updated existing evidence on the role of VD in the development of fragility syndromes such as DP and OP and the possible benefits of VD supplementation as a simple and harmful weapon against aging.

Vitamin D Alleviates Cadmium-Induced Inhibition of Chicken Bone Marrow Stromal Cells' Osteogenic Differentiation In Vitro

Vitamin D is a lipid soluble vitamin that is mostly used to treat bone metabolism-related diseases. In this study, the effect of Cd toxicity in vitro on osteogenic differentiation derived from BMSCs and the alleviating effect of lα, 25-(OH)2D3 were investigated. Cell index in real time was monitored using a Real-time cell analyzer (RTCA) system. The activity of alkaline phosphatase (ALP), and the calcified nodules and the distribution of Runx2 protein were detected using ALP staining, alizarin red staining, and immunofluorescence, respectively. Furthermore, the mitochondrial membrane potential and the apoptotic rate of BMSCs, the mRNA levels of RUNX2 and type Ⅰ collagen alpha2 (COL1A2) genes, and the protein expression of Col1 and Runx2 were detected using flow cytometry, qRT-PCR and western blot, respectively. The proliferation of BMSCs and osteogenic differentiation were enhanced after treatment with different concentrations of lα, 25-(OH)2D3 compared with the control group. However, 5 μmol/L Cd inhibited the proliferation of BMSCs. In addition, 10 nmol/L lα,25-(OH)2D3 attenuated the toxicity and the apoptosis of BMSCs treated by Cd, and also promoted the osteogenic differentiation including the activity of ALP, and the protein expression of Col1 and Runx2. lα, 25-(OH)2D3 can alleviate cadmium-induced osteogenic toxicity in White Leghorn chickens in vitro.

Tubular injury in diabetic kidney disease: molecular mechanisms and potential therapeutic perspectives

Diabetic kidney disease (DKD) is a chronic complication of diabetes and the leading cause of end-stage renal disease (ESRD) worldwide. Currently, there are limited therapeutic drugs available for DKD. While previous research has primarily focused on glomerular injury, recent studies have increasingly emphasized the role of renal tubular injury in the pathogenesis of DKD. Various factors, including hyperglycemia, lipid accumulation, oxidative stress, hypoxia, RAAS, ER stress, inflammation, EMT and programmed cell death, have been shown to induce renal tubular injury and contribute to the progression of DKD. Additionally, traditional hypoglycemic drugs, anti-inflammation therapies, anti-senescence therapies, mineralocorticoid receptor antagonists, and stem cell therapies have demonstrated their potential to alleviate renal tubular injury in DKD. This review will provide insights into the latest research on the mechanisms and treatments of renal tubular injury in DKD.

A review of the critical role of vitamin D axis on the immune system

In recent years, the physiological and molecular functions of vitamin D (Vit-D) have been deeply investigated. At first, Vit-D was considered a regulator of mineral and skeletal homeostasis. However, due to the extensive-expression pattern of Vit-D receptor (VDR) in almost every non-skeletal cell, Vit-D is considered mainly a multifunctional agent with broad effects on various tissues, notably the immune system. The expression of VDR in immune cells such as dendritic cells, monocyte/macrophage, neutrophils, B cells and T cells has been well demonstrated. Besides, such immune cells are capable of metabolizing the active form of Vit-D which means that it can module the immune system in both paracrine and autocrine manners. Vit-D binding protein (DBP), that regulates the levels and homeostasis of Vit-D, is another key molecule capable of modulating the immune system. Recent studies indicate that dysregulation of Vit-D axis, variations in the DBP and VDR genes, and Vit-D levels might be risk factors for the development of autoimmune disease. Here, the current evidence regarding the role of Vit-D axis on the immune system, as well as its role in the development of autoimmune disease will be clarified. Further insight will be given to those studies that investigated the association between single nucleotide polymorphisms of DBP and VDR genes with autoimmune disease susceptibility.

Vitamin D receptor gene polymorphisms influence on clinical profile and bone mineral density at different skeletal sites in postmenopausal osteoporotic women

Bone remodeling is marked by bone synthesis and absorption balance, and any altered dynamic in this process leads to osteoporosis (OP). The interaction of hormonal, environmental and genetic factors regulate bone metabolism. Since vitamin D displays a classic role in bone metabolism regulation, acting through vitamin D receptor (VDR), the genetic variants within VDR were the first ones associated with bone density and remodelling. Therefore, we investigated whether three single nucleotide polymorphisms (SNPs) within VDR were associated with OP differential susceptibility and clinical profile from postmenopausal versus healthy women from Northeast Brazil. Genetic association study enrolling 146 postmenopausal osteoporotic women as the patient group and 95 healthy age-matched women as the control group. We assessed three SNPs within VDR (rs11168268, rs1540339 and rs3890733), considering the clinical profile of all patients. Our results showed an association of rs11168268 G/G genotype with higher bone mineral density (BMD) mean for the total hip (A/A = 0.828 ± 0.09; A/G = 0.081 ± 0.13; G/G = 0.876 ± 0.12, p = .039), and the rs3890733 T/T genotype was associated with increased OP risk in patients below 60 years old (odds ratio [OR] = 5.12, 95% confidence interval [CI ]= 1.13-23.27, p = .012). The rs1540339 T/T genotype was associated with protection for individuals with low melanin deposition when compared to the high melanin deposition group (OR = 0.24, 95%CI = 0.06-0.94, p = .029). Additionally, 61% of patients presented deficient vitamin D serum levels. The SNP rs11168268 G/G was associated with a significantly increased mean total hip BMD in patients OP, highlighting this SNP and its relationship with BMD.

Latest Knowledge on the Role of Vitamin D in Hypertension

Hypertension is the third leading cause of the global disease burden, and while populations live longer, adopt more sedentary lifestyles, and become less economically concerned, the prevalence of hypertension is expected to increase. Pathologically elevated blood pressure (BP) is the strongest risk factor for cardiovascular disease (CVD) and related disability, thus making it imperative to treat this disease. Effective standard pharmacological treatments, i.e., diuretics, angiotensin converting enzyme (ACE) inhibitors, angiotensin receptor blocker (ARBs), beta-adrenergic receptor blockers (BARBs), and calcium channel blockers (CCBs), are available. Vitamin D (vitD) is known best for its role in bone and mineral homeostasis. Studies with vitamin D receptor (VDR) knockout mice show an increased renin-angiotensin-aldosterone system (RAAS) activity and increased hypertension, suggesting a key role for vitD as a potential antihypertensive agent. Similar studies in humans displayed ambiguous and mixed results. No direct antihypertensive effect was shown, nor a significant impact on the human RAAS. Interestingly, human studies supplementing vitD with other antihypertensive agents reported more promising results. VitD is considered a safe supplement, proposing its great potential as antihypertensive supplement. The aim of this review is to examine the current knowledge about vitD and its role in the treatment of hypertension.

Effect of calcitriol and calcium on basal ganglia calcification in hypoparathyroidism: experimental models

Basal ganglia calcification (BGC) is a common complication in hypoparathyroid patients, linked to hyperphosphatemia and altered vitamin-D and calcium homeostasis following conventional therapy. The pathogenesis of BGC in hypoparathyroidism is not clear. Recently, we developed an ex vivo model of BGC using rat-striatal cell culture in 10.0 mmol/L of β-glycerophosphate (31.8 mg/dL phosphate). However, the effect of 1,25(OH)2 D, calcium, and milder phosphate excess on BGC in hypoparathyroidism is not known. This study describes two modified ex vivo models investigating pathogenesis of BGC in 'drug-naïve' and 'conventionally treated' hypoparathyroid state. The first modification involved striatal cells cultured in low concentration 1,25(OH)2D (16.0 pg/mL), ionized calcium(0.99 mmol/L), hPTH(1-34) (6.0 pg/mL), and 2.68 mmol/L (8.3 mg/dL) of phosphate akin to 'drug-naïve' state for 24 days. In second modification, striatal cells were exposed to 46.0 pg/mL of 1,25(OH)2D, normal ionized calcium of 1.17 mmol/L, and 2.20 mmol/L (6.8 mg/dL) of phosphate akin to 'conventionally treated' state. Striatal cell culture under 'drug-naïve' state showed that even 16.0 pg/mL of 1,25(OH)2D enhanced the calcification. In 'conventionally treated' model, striatal cell calcification was enhanced in 54% cases over 'drug-naïve' state. Calcification in 'conventionally treated' state further increased on increasing phosphate to 8.3 mg/dL, suggesting importance of phosphatemic control in hypoparathyroid patients. Striatal cells in 'drug-naïve' state showed increased mRNA expression of pro-osteogenic Wnt3a, Cd133,Vglut-1-neuronal phosphate-transporters, calcium-ion channel-Trvp2,Alp, and Collagen-1α and decreased expression of Ca-II. These models suggest that in 'drug-naïve' state, 1,25(OH)2D along with moderately elevated phosphate increases the expression of pro-osteogenic molecules to induce BGC. Although normalization of calcium in 'conventionally treated' state increased the expression of Opg, Osterix, Alp, and Cav2, calcification increased only in a subset, akin to variation in progression of BGC in hypoparathyroid patients on conventional therapy.

Vitamin D and Bone: A Story of Endocrine and Auto/Paracrine Action in Osteoblasts

Despite its rigid structure, the bone is a dynamic organ, and is highly regulated by endocrine factors. One of the major bone regulatory hormones is vitamin D. Its renal metabolite 1α,25-OH2D3 has both direct and indirect effects on the maintenance of bone structure in health and disease. In this review, we describe the underlying processes that are directed by bone-forming cells, the osteoblasts. During the bone formation process, osteoblasts undergo different stages which play a central role in the signaling pathways that are activated via the vitamin D receptor. Vitamin D is involved in directing the osteoblasts towards proliferation or apoptosis, regulates their differentiation to bone matrix producing cells, and controls the subsequent mineralization of the bone matrix. The stage of differentiation/mineralization in osteoblasts is important for the vitamin D effect on gene transcription and the cellular response, and many genes are uniquely regulated either before or during mineralization. Moreover, osteoblasts contain the complete machinery to metabolize active 1α,25-OH2D3 to ensure a direct local effect. The enzyme 1α-hydroxylase (CYP27B1) that synthesizes the active 1α,25-OH2D3 metabolite is functional in osteoblasts, as well as the enzyme 24-hydroxylase (CYP24A1) that degrades 1α,25-OH2D3. This shows that in the past 100 years of vitamin D research, 1α,25-OH2D3 has evolved from an endocrine regulator into an autocrine/paracrine regulator of osteoblasts and bone formation.

Calcipotriol attenuates liver fibrosis through the inhibition of vitamin D receptor-mediated NF-κB signaling pathway

Liver fibrosis is an inevitable stage in the development of chronic liver disease to cirrhosis. Nonetheless, the interventional treatment and achieving control over the disease at this stage can substantially reduce the incidence of liver cirrhosis. To demonstrate these aspects, liver pathological sections of 18 patients with chronic liver disease are collected for research according to the degree of fibrosis. Further, the expressions of related proteins in each group are studied by the Western blot method. The cell proliferation and apoptosis are detected by CKK-8 and flow cytometry analyses. Further, a rat model with carbon tetrachloride (CCl₄)-induced liver fibrosis is employed to verify the effect and mechanism of VDR on the process of liver fibrosis in vivo. The expression of VDR in liver tissues of patients with liver fibrosis is negatively correlated with α-smooth muscle actin (α-SMA), Col-1, and liver fibrosis stages. Moreover, the tumor necrosis factor (TNF)-α stimulation could increase the proliferation of LX-2, up-regulate the expression of α-SMA, Col-1, NF-κB, p-IκBα, p-IKKβ, p-p65m, and some fibrosis factors, as well as down-regulate the expressions of VDR and matrix metalloproteinase-1 (MMP-1). Considering the protective actions of VDR, calcipotriol, a VDR agonist, effectively reduced the degree of liver fibrosis in a rat model of liver fibrosis by inhibiting the deposition of extracellular (ECM) and activation of hepatic stellate cells (HSCs), which is negatively correlated with the degree of liver fibrosis. Together, these shreds of evidence demonstrated that the calcipotriol showed great potential in effectively attenuating liver fibrosis.

Protective actions of vitamin D, anandamide and melatonin during vascular inflammation: Epigenetic mechanisms involved

Vascular inflammation is one of the main activating stimuli of cardiovascular disease and its uncontrolled development may worsen the progression and prognosis of these pathologies. Therefore, the search for new therapeutic options to treat this condition is undoubtedly needed. In this regard, it may be better to repurpose endogenous anti-inflammatory compounds already known, in addition to synthesizing new compounds for therapeutic purposes. It is well known that vitamin D, anandamide, and melatonin are promising endogenous substances with powerful and wide-spread anti-inflammatory properties. Currently, the epigenetic mechanisms underlying these effects are often unknown. This review summarizes the potential epigenetic mechanisms by which vitamin D, anandamide, and melatonin attenuate vascular inflammation. This information could contribute to the improvement in the therapeutic management of multiple pathologies associated with blood vessel inflammation, through the pharmacological manipulation of new target sites that until now have not been addressed.

Effects of Extracellular Osteoanabolic Agents on the Endogenous Response of Osteoblastic Cells

The complex multidimensional skeletal organization can adapt its structure in accordance with external contexts, demonstrating excellent self-renewal capacity. Thus, optimal extracellular environmental properties are critical for bone regeneration and inextricably linked to the mechanical and biological states of bone. It is interesting to note that the microstructure of bone depends not only on genetic determinants (which control the bone remodeling loop through autocrine and paracrine signals) but also, more importantly, on the continuous response of cells to external mechanical cues. In particular, bone cells sense mechanical signals such as shear, tensile, loading and vibration, and once activated, they react by regulating bone anabolism. Although several specific surrounding conditions needed for osteoblast cells to specifically augment bone formation have been empirically discovered, most of the underlying biomechanical cellular processes underneath remain largely unknown. Nevertheless, exogenous stimuli of endogenous osteogenesis can be applied to promote the mineral apposition rate, bone formation, bone mass and bone strength, as well as expediting fracture repair and bone regeneration. The following review summarizes the latest studies related to the proliferation and differentiation of osteoblastic cells, enhanced by mechanical forces or supplemental signaling factors (such as trace metals, nutraceuticals, vitamins and exosomes), providing a thorough overview of the exogenous osteogenic agents which can be exploited to modulate and influence the mechanically induced anabolism of bone. Furthermore, this review aims to discuss the emerging role of extracellular stimuli in skeletal metabolism as well as their potential roles and provide new perspectives for the treatment of bone disorders.

The Impact of Vitamin D on Skin Aging

The active metabolites of vitamin D₃ (D₃) and lumisterol (L₃) exert a variety of antiaging and photoprotective effects on the skin. These are achieved through immunomodulation and include anti-inflammatory actions, regulation of keratinocytes proliferation, and differentiation programs to build the epidermal barrier necessary for maintaining skin homeostasis. In addition, they induce antioxidative responses, inhibit DNA damage and induce DNA repair mechanisms to attenuate premature skin aging and cancerogenesis. The mechanism of action would involve interaction with multiple nuclear receptors including VDR, AhR, LXR, reverse agonism on RORα and -γ, and nongenomic actions through 1,25D₃-MARRS receptor and interaction with the nongenomic binding site of the VDR. Therefore, active forms of vitamin D₃ including its canonical (1,25(OH)₂D₃) and noncanonical (CYP11A1-intitated) D₃ derivatives as well as L₃ derivatives are promising agents for the prevention, attenuation, or treatment of premature skin aging. They could be administrated orally and/or topically. Other forms of parenteral application of vitamin D₃ precursor should be considered to avoid its predominant metabolism to 25(OH)D₃ that is not recognized by CYP11A1 enzyme. The efficacy of topically applied vitamin D₃ and L₃ derivatives needs further clinical evaluation in future trials.

Vitamin D Receptor Mediates a Myriad of Biological Actions Dependent on Its 1,25-Dihydroxyvitamin D Ligand: Distinct Regulatory Themes Revealed by Induction of Klotho and Fibroblast Growth Factor-23

The hormonal vitamin D metabolite, 1,25‐dihydroxyvitamin D [1,25(OH)₂D], produced in kidney, acts in numerous end organs via the nuclear vitamin D receptor (VDR) to trigger molecular events that orchestrate bone mineral homeostasis. VDR is a ligand‐controlled transcription factor that obligatorily heterodimerizes with retinoid X receptor (RXR) to target vitamin D responsive elements (VDREs) in the vicinity of vitamin D‐regulated genes. Circulating 1,25(OH)₂D concentrations are governed by PTH, an inducer of renal D‐hormone biosynthesis catalyzed by CYP27B1 that functions as the key player in a calcemic endocrine circuit, and by fibroblast growth factor‐23 (FGF23), a repressor of the CYP27B1 renal enzyme, creating a hypophosphatemic endocrine loop. 1,25(OH)₂D/VDR–RXR acts in kidney to induce Klotho (a phosphaturic coreceptor for FGF23) to correct hyperphosphatemia, NPT2a/c to correct hypophosphatemia, and TRPV5 and CaBP28k to enhance calcium reabsorption. 1,25(OH)₂D‐liganded VDR–RXR functions in osteoblasts/osteocytes by augmenting RANK‐ligand expression to paracrine signal osteoclastic bone resorption, while simultaneously inducing FGF23, SPP1, BGLP, LRP5, ANK1, ENPP1, and TNAP, and conversely repressing RUNX2 and PHEX expression, effecting localized control of mineralization to sculpt the skeleton. Herein, we document the history of 1,25(OH)₂D/VDR and summarize recent advances in characterizing their physiology, biochemistry, and mechanism of action by highlighting two examples of 1,25(OH)₂D/VDR molecular function. The first is VDR‐mediated primary induction of Klotho mRNA by 1,25(OH)₂D in kidney via a mechanism initiated by the docking of liganded VDR–RXR on a VDRE at −35 kb in the mouse Klotho gene. In contrast, the secondary induction of FGF23 by 1,25(OH)₂D in bone is proposed to involve rapid nongenomic action of 1,25(OH)₂D/VDR to acutely activate PI3K, in turn signaling the induction of MZF1, a transcription factor that, in cooperation with c‐ets1‐P, binds to an enhancer element centered at −263 bp in the promoter‐proximal region of the mouse fgf23 gene. Chronically, 1,25(OH)₂D‐induced osteopontin apparently potentiates MZF1. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Vitamin D improves pulmonary function in a rat model for congenital diaphragmatic hernia

A congenital diaphragmatic hernia (CDH) is an anomaly caused by defects in the diaphragm; the resulting limited thorax cavity in turn restricts lung growth (pulmonary hypoplasia). This condition is related to pulmonary hypertension. Despite advances in neonatal CDH therapy, the mortality for severe pulmonary hypoplasia remains high. Therefore, it is essential to establish prenatal therapeutic interventions. Vitamin D was reported to have beneficial effects on adult pulmonary hypertension. This study aims to evaluate the efficacy of prenatal vitamin D administration for CDH. First, serum 25-hydroxyvitamin D [25(OH)D] levels in umbilical cord blood were evaluated among CDH newborns. Second, Sprague Dawley rat CDH models were exposed to nitrofen on embryo day 9 (E9). Randomly selected rats in the nitrofen-treated group were infused with calcitriol from E9 to E21. Samples from CDH pups diagnosed after birth were used for lung weight measurements, blood gas analysis, and immunohistochemical analysis. Third, microarray analysis was performed to examine the effect of vitamin D on gene expression profiles in CDH pulmonary arterial tissues. Serum 25(OH)D levels in the umbilical cord blood of newborns who did not survive were significantly lower than those who were successfully discharged. Prenatal vitamin D showed no significant effect on CDH incidence or lung weight but attenuated alveolarization and pulmonary artery remodeling accompanied the improved blood gas parameters. Vitamin D inhibited several gene expression pathways in the pulmonary arteries of CDH rats. Our results suggest that prenatal vitamin D administration attenuates pulmonary vascular remodeling by influencing several gene pathways in CDH.

Pomegranate derivative urolithin A enhances vitamin D receptor signaling to amplify serotonin-related gene induction by 1,25-dihydroxyvitamin D

Mediated by the nuclear vitamin D receptor (VDR), the hormonally active vitamin D metabolite, 1,25-dihydroxyvitamin D₃ (1,25D), is known to regulate expression of genes impacting calcium and phosphorus metabolism, the immune system, and behavior. Urolithin A, a nutrient metabolite derived from pomegranate, possibly acting through AMP kinase (AMPK) signaling, supports respiratory muscle health in rodents and longevity in C. elegans by inducing oxidative damage-reversing genes and mitophagy. We show herein that urolithin A enhances transcriptional actions of 1,25D driven by co-transfected vitamin D responsive elements (VDREs), and dissection of this genomic effect in cell culture reveals: 1) urolithin A concentration-dependency, 2) occurrence with isolated natural VDREs, 3) nuclear receptor selectivity for VDR over ER, LXR and RXR, and 4) significant 3- to 13-fold urolithin A-augmentation of 1,25D-dependent mRNA encoding the widely expressed 1,25D-detoxification enzyme, CYP24A1, a benchmark vitamin D target gene. Relevant to potential behavioral effects of vitamin D, urolithin A elicits enhancement of 1,25D-dependent mRNA encoding tryptophan hydroxylase-2 (TPH2), the serotonergic neuron-expressed initial enzyme in tryptophan metabolism to serotonin. Employing quantitative real time-PCR, we demonstrate that TPH2 mRNA is induced 1.9-fold by 10 nM 1,25D treatment in culture of differentiated rat serotonergic raphe (RN46A-B14) cells, an effect magnified 2.5-fold via supplementation with 10 μM urolithin A. This potentiation of 1,25D-induced TPH2 mRNA by urolithin A is followed by a 3.1- to 3.7-fold increase in serotonin concentration in culture medium from the pertinent neuronal cell line, RN46A-B14. These results are consistent with the concept that two natural nutrient metabolites, urolithin A from pomegranate and 1,25D from sunlight/vitamin D, likely acting via AMPK and VDR, respectively, cooperate mechanistically to effect VDRE-mediated regulation of gene expression in neuroendocrine cells. Finally, gedunin, a neuroprotective natural product from Indian neem tree that impacts the brain derived neurotropic factor pathway, similarly potentiates 1,25D/VDR-action.

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Hormonal 1,25-dihydroxyvitamin D acts in brain to induce tryptophan hydroxylase-2.

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Urolithin A derived from ellagitannins in pomegranates curbs neuroinflammation.

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Urolithin A enhances the transcriptional actions of 1,25-dihydroxyvitamin D.

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Urolithin A raises 1,25-dihydroxyvitamin D-induced tryptophan hydroxylase-2 mRNA.

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Serotonin rises in raphe cells exposed to urolithin A and 1,25-dihydroxyvitamin D.

Vitamin D Binding Protein (VDBP) and Its Gene Polymorphisms-The Risk of Malignant Tumors and Other Diseases

Vitamin D is an important component of the endocrine system that controls calcium homeostasis and bone mineralization. Because of the very short half-life of free serum vitamin D it is stabilized and transported to target tissues by being bound to the vitamin D binding protein (VDBP). The most common polymorphisms: rs4588 and rs7041 in the vitamin D binding protein gene may correlate with differences in vitamin D status in the serum. This review presents data that relate to the presence of genetic variants in the VDBP gene in correlation with certain diseases, mostly concerning cancers (breast, prostate, pancreatic, lung, colorectal, basal cell carcinoma cancer and cutaneous melanoma) or other related diseases (thyroid autoimmunity disorders, obesity, diabetes mellitus, bone metabolism, rheumatoid arthritis, ankylosing spondylitis, asthma, chronic obstructive pulmonary disease, tuberculosis and coronary artery diseases).

Vitamin D Receptor Polymorphisms in Sex-Frailty Paradox

The “male-female health-survival paradox” evidences that the survival advantage observed in women is linked to higher rates of disability and poor health status compared to men, a phenomenon also called the “sex-frailty paradox”. The depletion of vitamin D seems to play a role in the fragilization of old persons, and genetic polymorphisms of the vitamin D receptor (VDR) gene seem to be involved in regulating the vitamin D pathway. This study correlated the VDR gene polymorphisms (FokI, ApaI, BsmiI, and TaqI) with frailty, computed by frailty index (FI), in 202 persons (127 women and 75 men, aged from 60 to 116 years), aiming to capture the involvement of vitamin D in the sex-frailty paradox. The results showed slightly higher FI (p = 0.05), lower levels of 25(OH)D (p = 0.04), and higher levels of parathyroid hormone PTH (p = 0.002) and phosphorus (p < 0.001) in women than in men. Interestingly, the ApaI minor allele (Aa + aa) showed a significant positive association with FI (p = 0.03) and a negative association with inorganic phosphorus values (p = 0.04) compared to AA genotype only in women, regardless of age. The exact mechanism and the causal role that, in old women, links ApaI polymorphism with frailty are still unclear. However, we could speculate that a specific genetic profiling, other than 25(OH)D levels, play a role in the sex-frailty paradox.

Vitamin D deficiency as a potential risk factor for accelerated aging, impaired hippocampal neurogenesis and cognitive decline: a role for Wnt/β-catenin signaling

Vitamin D is an essential fat-soluble vitamin that participates in several homeostatic functions in mammalian organisms. Lower levels of vitamin D are produced in the older population, vitamin D deficiency being an accelerating factor for the progression of the aging process. In this review, we focus on the effect that vitamin D exerts in the aged brain paying special attention to the neurogenic process. Neurogenesis occurs in the adult brain in neurogenic regions, such as the dentate gyrus of the hippocampus (DG). This region generates new neurons that participate in cognitive tasks. The neurogenic rate in the DG is reduced in the aged brain because of a reduction in the number of neural stem cells (NSC). Homeostatic mechanisms controlled by the Wnt signaling pathway protect this pool of NSC from being depleted. We discuss in here the crosstalk between Wnt signaling and vitamin D, and hypothesize that hypovitaminosis might cause failure in the control of the neurogenic homeostatic mechanisms in the old brain leading to cognitive impairment. Understanding the relationship between vitamin D, neurogenesis and cognitive performance in the aged brain may facilitate prevention of cognitive decline and it can open a door into new therapeutic fields by perspectives in the elderly.

Vitamin D Deficiency and Oral Health: A Comprehensive Review

Vitamin D (VD) levels have been gaining growing attention in Oral Health. During growth and adulthood, VD deficiency (VDD) is associated with a wide variety of oral health disorders, and impaired VD synthesis may expedite some of these conditions. In children, severe VDD can induce defective tooth mineralization, resulting in dentin and enamel defects. As a consequence, these defects may increase the risk of the onset and progression of dental caries. Further, VDD has been associated with higher prevalence of periodontitis and gingival inflammation, and several recent preclinical and clinical studies have unveiled potential pathways through which Vitamin D may interact with the periodontium. VDD correction through supplementation may contribute to a successful treatment of periodontitis; however, alveolar bone regeneration procedures performed in baseline VDD patients seem more prone to failure. Vitamin D may also be linked with some oral pathology entities such as certain oral cancers and events of osteonecrosis of the jaw. This review aims to provide comprehensive evidence of how VD levels should be considered to promote good oral health, and to summarize how VDD may hamper oral development and its role in certain oral conditions.

Dietary Habits and Nutrition in Rheumatoid Arthritis: Can Diet Influence Disease Development and Clinical Manifestations?

Rheumatoid arthritis (RA) is a systemic, autoimmune disease characterized by joint involvement, with progressive cartilage and bone destruction. Genetic and environmental factors determine RA susceptibility. In recent years, an increasing number of studies suggested that diet has a central role in disease risk and progression. Several nutrients, such as polyunsaturated fatty acids, present anti-inflammatory and antioxidant properties, featuring a protective role for RA development, while others such as red meat and salt have a harmful effect. Gut microbiota alteration and body composition modifications are indirect mechanisms of how diet influences RA onset and progression. Possible protective effects of some dietary patterns and supplements, such as the Mediterranean Diet (MD), vitamin D and probiotics, could be a possible future adjunctive therapy to standard RA treatment. Therefore, a healthy lifestyle and nutrition have to be encouraged in patients with RA.

Probiotic Lactobacillus strains from Mongolia improve calcium transport and uptake by intestinal cells in vitro

The aim of this study was to investigate the probiotic properties of 174 Lactobacillus strains isolated from Mongolian dairy products, and particularly their impact on intestinal calcium uptake and absorption. All isolates underwent a first screening based on cell surface hydrophobicity, acid tolerance, tolerance to gastro-intestinal digestion, autoaggregation, adhesion and cytotoxicity against intestinal cells. Six Lactobacillus strains from different species (L. casei, L. kefiranofaciens, L. plantarum, L. fermentum, L. helveticus and L. delbrueckii) were selected, and their impact on intestinal calcium uptake and transport was investigated using Caco-2. Five strains were able to improve total calcium transport after 24 h contact with a differentiated Caco-2 cell monolayer. Concomitantly the L. plantarum strain was able to increase cellular calcium uptake in Caco-2 cells by 10% in comparison to control conditions. To determine which pathway(s) of calcium absorption was modulated by the strains, a qPCR-based study on 4 genes related to calcium/vitamin D metabolism or tight junction integrity was conducted on mucus-secreting intestinal HT-29 MTX cells. The L. plantarum strain modulates the transcellular pathway by regulating the expression of vitamin D receptor (1.79 fold of control) and calcium transporter (4.77 fold of control) while the L. delbrueckii strain acts on the paracellular pathway by modulating claudin-2 expression (2.83 fold of control). This work highlights the impact of Lactobacillus probiotic strains on intestinal calcium absorption and for the first time give some evidence about the cellular pathways involved.

Vitamin D and Male Erectile Function: An Updated Review

Literature support that vitamin-D is important for different systems of the human body including, but not limited to endocrine and immune systems, vasculature and endothelial function of the body. Male erectile function depends on many factors and can be perceived as a health indicator of the body. Epidemiological data have shown that vitamin-D deficiency is also associated with erectile dysfunction. In this review, our aim is to interpret the mechanisms by which vitamin-D might regulate anatomy and physiology of penis. Evidence showed that vitamin-D is needed for an adequate erectile function. Briefly, vitamin-D is crucial for a better healthy body and sexual activity.

Vitamin D Inhibition of TRPV5 Expression During Osteoclast Differentiation

BACKGROUND

Vitamin D is an important steroid that can regulate bone metabolism including osteoclast (OC) differentiation. Transient receptor potential cation channel subfamily V member 5 (TRPV5), is a calcium channel protein involved in OC differentiation. However, the impact of vitamin D on TRPV5 expression during OC differentiation is not clear.

OBJECTIVES

To determine if 1,25-dihydroxyvitamin D3 (1,25(OH)₂D₃) regulates the expression of TRPV5 during OC differentiation.

METHODS

Bone marrow mononuclear macrophage (BMMs) were induced to differentiate into OC with or without treatment with 10 nM 1,25(OH)₂D₃. The expression levels of vitamin D receptor (VDR) and TRPV5 were examined. The expression of several OC markers, including tartrate resistant acid phosphatase (TRAP), carbonic anhydrase II (Ca II), cathepsin K (CTSK), and vacuolar-type H⁺-ATPase (V-ATPase) were also detected.

RESULTS

We found that the VDR was expressed in murine bone marrow-derived macrophages at the early stage of OC differentiation. TRPV5 expression was increased during OC differentiation, which was down-regulated by 1,25(OH)₂D₃ after a prolonged exposure. The 1,25(OH)₂D₃ and TRPV5 inhibitors inhibited OC differentiation.

CONCLUSIONS

1,25(OH)₂D₃ can inhibit TRPV5 expression as well as TRPV5 inhibitors during OC differentiation. This suggests that 1,25(OH)₂D₃ may suppress OC differentiation by inhibiting TRPV5 expression.

1,25-Dihydroxyvitamin D exerts an antiaging role by activation of Nrf2-antioxidant signaling and inactivation of p16/p53-senescence signaling

We tested the hypothesis that 1,25‐dihydroxyvitamin D₃[1α,25(OH)₂D₃] has antiaging effects via upregulating nuclear factor (erythroid‐derived 2)‐like 2 (Nrf2), reducing reactive oxygen species (ROS), decreasing DNA damage, reducing p16/Rb and p53/p21 signaling, increasing cell proliferation, and reducing cellular senescence and the senescence‐associated secretory phenotype (SASP). We demonstrated that 1,25(OH)₂D₃‐deficient [1α(OH)ase^−/−] mice survived on average for only 3 months. Increased tissue oxidative stress and DNA damage, downregulated Bmi1 and upregulated p16, p53 and p21 expression levels, reduced cell proliferation, and induced cell senescence and the senescence‐associated secretory phenotype (SASP) were observed. Supplementation of 1α(OH)ase^−/− mice with dietary calcium and phosphate, which normalized serum calcium and phosphorus, prolonged their average lifespan to more than 8 months with reduced oxidative stress and cellular senescence and SASP. However, supplementation with exogenous 1,25(OH)₂D₃ or with combined calcium/phosphate and the antioxidant N‐acetyl‐l‐cysteine prolonged their average lifespan to more than 16 months and nearly 14 months, respectively, largely rescuing the aging phenotypes. We demonstrated that 1,25(OH)₂D₃exerted an antioxidant role by transcriptional regulation of Nrf2 via the vitamin D receptor (VDR). Homozygous ablation of p16 or heterozygous ablation of p53 prolonged the average lifespan of 1α(OH)ase^−/− mice on the normal diet from 3 to 6 months by enhancing cell proliferative ability and reducing cell senescence or apoptosis. This study suggests that 1,25(OH)₂D₃ plays a role in delaying aging by upregulating Nrf2, inhibiting oxidative stress and DNA damage，inactivating p53‐p21 and p16‐Rb signaling pathways, and inhibiting cell senescence and SASP.

Vitamin D Deficiency in the Gulf Cooperation Council: Exploring the Triad of Genetic Predisposition, the Gut Microbiome and the Immune System

Vitamin D is a fat soluble secosteroid that is primarily synthesized in the skin upon exposure to Ultraviolet B (UVB) sun rays. Vitamin D is essential for the growth and development of bones and helps in reducing inflammation by strengthening muscles and the immune system. Despite the endless supply of sunlight in the Gulf Cooperation Council (GCC) countries which includes United Arab Emirates, Qatar, Kuwait, Bahrain, Saudi Arabia, and Oman, Vitamin D deficiency in the (GCC) general population at various age groups remains alarmingly high. In parallel runs the increasing prevalence of acute and chronic illnesses including, autoimmune diseases, cancer, type 1 diabetes mellitus, cardiovascular disease and Inflammatory bowel disease in the adult as well as the pediatric population of these countries. The exact association between Vitamin D deficiency and chronic disease conditions remains unclear; however, studies have focused on the mechanism of Vitamin D regulation by assessing the role of the Vitamin D associated genes/proteins such as VDR (Vitamin D receptor), VDBP (Vitamin D Binding protein), CYP27B1 as these are integral parts of the Vitamin D signaling pathway. VDR is known to regulate the expression of more than 200 genes across a wide array of tissues in the human body and may play a role in controlling the Vitamin D levels. Moreover, reduced Vitamin D level and downregulation of VDR have been linked to gut dysbiosis, highlighting an intriguing role for the gut microbiome in the Vitamin D metabolism. However, this role is not fully described yet. In this review, we aim to expand our understanding of the causes of Vitamin D deficiency in the GCC countries and explore the potential relationship between the genetic predisposition, Vitamin D levels, immune system and the gut microbiome composition. Trying to unravel this complex interaction may aid in understanding the mechanism by which Vitamin D contributes to various disease conditions and will pave the way toward new therapeutics treatments for Vitamin D deficiency and its associated outcomes.

Vitamin D and its receptor polymorphisms: New possible prognostic biomarkers in leukemias

Several factors such as chromosomal translocations, gene mutations, and polymorphisms are involved in the pathogenesis of leukemia/lymphoma. Recently, the role of vitamin D (VD) and vitamin D receptor (VDR) polymorphisms in hematologic malignancies has been considered. In this review, we examine the possible role of VD levels, as well as VDR polymorphisms as prognostic biomarkers in leukemia/lymphoma. Relevant English language literature were searched and retrieved from Google Scholar search engine (1985-2017). The following keywords were used: vitamin D, vitamin D receptor, leukemia, lymphoma, and polymorphism. Increased serum levels of VD in patients with leukemia are associated with a better prognosis. However, low VD levels are associated with a poor prognosis, and VDR polymorphisms in various leukemias can have prognostic value. VD biomarker can be regarded as a potential prognostic factor for a number of leukemias, including acute myeloblastic leukemia (AML), chronic lymphoblastic leukemia (CLL), and diffuse large B-cell lymphoma (DLBCL). There is a significant relationship between different polymorphisms of VDR (including Taq I and Fok I) with several leukemia types such as ALL and AML, which may have prognostic value.

Association of SNP-SNP Interactions Between RANKL, OPG, CHI3L1, and VDR Genes With Breast Cancer Risk in Egyptian Women

BACKGROUND

Genetic susceptibility for breast cancer (BC) is still poorly understood. A combination of multiple low-penetrant alleles of cancer-related genes and gene-gene interactions (epistasis) contributes to BC risk. Genetic variants in receptor activator of nuclear factor κB ligand (RANKL), osteoprotegerin (OPG), chitinase-3-like protein 1 (CHI3L1), and vitamin D receptor (VDR) genes are implicated in breast carcinogenesis; however, the influence of their epistatic effects on BC susceptibility has not yet been studied. We investigated the association of single nucleotide polymorphism (SNP)-SNP interactions and haplotypes of 6 SNPs in these 4 genes with the genetic predisposition of BC in Egyptian women.

PATIENTS AND METHODS

Data of 115 BC patients and 120 cancer-free controls were studied. Association tests were conducted using logistic regression models.

RESULTS

Individual SNPs showed weak statistical significance with BC susceptibility. The interactions between RANKL-rs9533156 and OPG-rs2073618; OPG-rs2073618 with CHI3L1-rs4950928, VDR-rs2228570 and VDR-rs1544410; OPG-rs2073617 and VDR-rs1544410; VDR-rs2228570 and VDR-rs1544410 were strongly associated with increased BC risk after adjustment for multiple comparisons. No SNPs were in strong linkage disequilibrium. The TCTCTG-rs9533156-rs2073618-rs2073617-rs4950928-rs2228570-rs1544410 haplotype was significantly associated with increased BC risk (adjusted odds ratio = 8.33; 95% confidence interval, 1.32-52.46; P = .025) compared with controls. TCCCTG haplotype stratified BC patients according to estrogen receptor/progesterone receptor status. TCTCTA was positively associated, and TCTCTG and TGTCTG haplotypes inversely correlated with bone metastasis. Bioinformatic analysis revealed 13 proteins commonly interacting with our 4 genes; the most significant was signal transducer and activator of transcription 5B.

CONCLUSION

Our results suggested that a stronger combined effect of SNPs in RANKL, OPG, CHI3L1, and VDR genes via gene-gene interaction may help predict BC risk and prognosis.

Induction of anti-aging gene klotho with a small chemical compound that demethylates CpG islands

Klotho (KL) is described as an anti-aging gene because mutation of Kl gene leads to multiple pre-mature aging phenotypes and shortens lifespan in mice. Growing evidence suggests that an increase in KL expression may be beneficial for age-related diseases such as arteriosclerosis and diabetes. It remains largely unknown, however, how Kl expression could be induced. Here we discovered novel molecular mechanism for induction of Kl expression with a small molecule ‘Compound H’, N-(2-chlorophenyl)-1H-indole-3-caboxamide. Compound H was originally identified through a high-throughput screening of small molecules for identifying Kl inducers. However, how Compound H induces Kl expression has never been investigated. We found that Compound H increased Kl expression via demethylation in CpG islands of the Kl gene. The demethylation was accomplished by activating demethylases rather than inhibiting methylases. Due to demethylation, Compound H enhanced binding of transcription factors, Pax4 and Kid3, to the promoter of the Kl gene. Pax4 and Kid3 regulated Kl promoter activity positively and negatively, respectively. Thus, our results show that demethylation is an important molecular mechanism that mediates Compound H-induced Kl expression. Further investigation is warranted to determine whether Compound H demethylates the Kl gene in vivo and whether it can serve as a therapeutic agent for repressing or delaying the onset of age-related diseases.

Advanced maternal age impairs spatial learning capacity in young adult mouse offspring

Effects of maternal aging on the offspring cognitive function remain controversial in population-based investigations, and information available in animal studies is very limited. We investigated the impact of a delayed first natural pregnancy on pregnancy outcomes in the mouse model. Spatial learning capacity in young adult mouse offspring was observed by step-down passive avoidance task and Morris water maze (MWM). Maternal serum α-klotho was measured by ELISA. Morphological characteristics of fetoplacental unit and offspring brain were identified by H&E and immunohistochemistry. Klotho, VDR and other related genes expression were quantified by real-time-RT-PCR and western blot. We found delayed pregnancy reduced fertility in female mice by three-fold (Young vs. Old: 5.0% vs. 20.7%), and increased adverse pregnant outcomes by eight-fold (Young vs. Old: 3.0% vs. 27.5%). Mice born to old mothers exhibited shorter retention trial latency in passive avoidance task and longer latency to find the platform in MWM, suggesting worse performance on the tests that measure learning and memory. Serum α-klotho level was lower in old female mice before pregnancy, whereas became comparable after pregnancy. Vitamin D receptor (VDR) expression, both in mRNA and protein, markedly decreased during the early stage of fetoplacental unit in old mice, especially in trophoblast giant cells when compared with that of young mice. Importantly, consistent with fetoplacental unit, VDR expression also declined in hippocampus from offspring born to old mice. These results suggest that young adult offspring from aged mothers exhibited worse cognitive function and the reduced VDR expression during fetoplacental development might play an important role.

Both ligand and VDR expression levels critically determine the effect of 1α,25-dihydroxyvitamin-D3 on osteoblast differentiation

Previous studies have shown that 1α,25-dihydroxyvitamin D₃ (1,25D) through vitamin D receptor (VDR) signalling has both catabolic and anabolic effects on osteoblast differentiation. However, the mechanism of these differential effects by 1,25D is not fully understood. In this study, mice with three different genetic backgrounds, representing a normal VDR level (wild-type, WT), VDR over-expression specifically in mature osteoblasts (ObVDR-B6) and global VDR knockout (VDRKO), were utilised to generate primary osteoblast-like cultures to further elucidate the effects of 1,25D on osteoblast differentiation. Our data confirm the importance of VDR in the late stage of osteogenic differentiation and also for the expression of factors critical for osteoblastic support of osteoclast formation. This study also demonstrates the differential effects of a pharmacological level of 1,25D (1nM) on the expression of osteogenic differentiation markers, including Ocn and Sost, depending on the relative level of VDR. Our findings suggest that 1,25D plays an inhibitory role in matrix mineralisation, possibly through the modulation of the tissue non-specific alkaline phosphatase to ectonucleotide pyrophosphatase/phosphodiesterase 1 axis, in a VDR level-dependent manner. We conclude that the relative VDR level and the 1,25D availability to cells, are important co-determinants for whether 1,25D plays a promoting or suppressive role in osteoblast-mediated osteogenic activity.

The effect of high-dose vitamin D3 supplementation on bone mineral density in subjects with prediabetes

The rationale of this study was to determine the effect of high-dose vitamin D₃ supplementation on bone mineral density (BMD). Prediabetic males given vitamin D had significantly less reduction in BMD at the femoral neck compared to the controls. The clinical implications of our findings require further investigation.

INTRODUCTION

Type 2 diabetes mellitus is associated with increased fracture risk, and recent studies show crosstalk between bone and glucose metabolism. Few studies have investigated the effect of vitamin D supplementation on the bone without additional calcium. In the present study, we aimed to determine whether a high dose of vitamin D₃ could improve bone mass density (BMD) in prediabetic subjects.

METHODS

The current study was conducted as a secondary research on a previously performed trial, in which 511 subjects with prediabetes were randomized to vitamin D₃ (20,000 IU per week) versus placebo for 5 years. BMD was measured using dual-energy X-ray absorptiometry (DEXA).

RESULTS

Two hundred and fifty-six subjects were randomized to vitamin D and 255 to placebo. Mean baseline serum 25-hydroxyvitamin D (25(OH)D) level was 60 nmol/L. Two hundred and two and 214 in the vitamin D and placebo groups, respectively, completed BMD measurements, whereas one in each group was excluded due to use of bisphosphonates. Males given vitamin D had significantly less reduction in BMD at the femoral neck measurement site compared to the controls (0.000 versus - 0.010 g/cm², p = 0.008). No significant differences between intervention groups were seen at the total hip measurement site, regarding both males and females.

CONCLUSIONS

Vitamin D₃ supplementation alone may be beneficial in males with prediabetes, but confirmatory studies are needed.

Vitamin D receptor signaling improves Hutchinson-Gilford progeria syndrome cellular phenotypes

Hutchinson-Gilford Progeria Syndrome (HGPS) is a devastating incurable premature aging disease caused by accumulation of progerin, a toxic lamin A mutant protein. HGPS patient-derived cells exhibit nuclear morphological abnormalities, altered signaling pathways, genomic instability, and premature senescence. Here we uncover new molecular mechanisms contributing to cellular decline in progeria. We demonstrate that HGPS cells reduce expression of vitamin D receptor (VDR) and DNA repair factors BRCA1 and 53BP1 with progerin accumulation, and that reconstituting VDR signaling via 1α,25-dihydroxyvitamin D₃ (1,25D) treatment improves HGPS phenotypes, including nuclear morphological abnormalities, DNA repair defects, and premature senescence. Importantly, we discovered that the 1,25D/VDR axis regulates LMNA gene expression, as well as expression of DNA repair factors. 1,25D dramatically reduces progerin production in HGPS cells, while stabilizing BRCA1 and 53BP1, two key factors for genome integrity. Vitamin D/VDR axis emerges as a new target for treatment of HGPS and potentially other lamin-related diseases exhibiting VDR deficiency and genomic instability. Because progerin expression increases with age, maintaining vitamin D/VDR signaling could keep the levels of progerin in check during physiological aging.

Vitamin D Effect on Bone Mineral Density and Fractures

One hundred years ago, vitamin D was identified as the cause and cure of osteomalacia. This role remains firmly established. Vitamin D influences skeletal mineralization principally through the regulation of intestinal calcium absorption. It has been proposed that vitamin D has direct beneficial effects on bone (besides the prevention of osteomalacia), but these have been difficult to establish in clinical trials. Meta-analyses of vitamin D trials show no effects on bone density or fracture risk when the baseline 25-hydroxyvitamin D is >40 nmol/L. A daily dose of 400 to 800 IU vitamin D₃ is usually adequate to correct such deficiency.

Vitamin D deficiency accelerates ageing and age-related diseases: a novel hypothesis

Ageing can occur at different rates, but what controls this variable rate is unknown. Here I have developed a hypothesis that vitamin D may act to control the rate of ageing. The basis of this hypothesis emerged from studyng the various cellular processes that control ageing. These processes such as autophagy, mitochondrial dysfunction, inflammation, oxidative stress, epigenetic changes, DNA disorders and alterations in Ca²⁺ and reactive oxygen species (ROS) signalling are all known to be regulated by vitamin D. The activity of these processes will be enhanced in individuals that are deficient in vitamin D. Not only will this increase the rate of ageing, but it will also increase the probability of developing age-related diseases such as Alzheimer's disease, Parkinson's disease, multiple sclerosis and cardiovascular disease. In individual with normal vitamin D levels, these ageing-related processes will occur at lower rates resulting in a reduced rate of ageing and enhanced protection against these age-related diseases.

Vitamin D endocrinology of bone mineralization

Bone is a dynamic tissue that is strongly influenced by endocrine factors to restore the balance between bone resorption and bone formation. Bone formation involves the mineralization of the extracellular matrix formed by osteoblasts. In this process the role of vitamin D (1α,25(OH)₂D₃) is both direct and indirect. The direct effects are enabled via the Vitamin D Receptor (VDR); the outcome is dependent on the presence of other factors as well as origin of the osteoblasts, treatment procedures and species differences. Vitamin D stimulates mineralization of human osteoblasts but is often found inhibitory for mineralization of murine osteoblasts. In this review we will overview the current knowledge of the role of the vitamin D endocrine system in controlling the mineralization process in bone.

Vitamin D: Musculoskeletal health

Perhaps the role of Vitamin D supplementation has been most exhaustively studied in calcium absorption, skeletal wellbeing, muscular potency, balance and risk of falling. Nonetheless, new data has emerged and the recent research on sarcopenia makes the topic increasingly interesting. Given the socioeconomic burden of the musculoskeletal consequences of hypovitaminosis D it is vital to keep abreast with the latest literature in the field. The recommended Vitamin D supplementation dose should suffice to increase the serum 25 hydroxyvitamin D level to 30 ng/mL (75 nmol/L) and this level should be optimally maintained with a maintenance dose, particularly for those diagnosed with osteoporosis.

SIRT1 enzymatically potentiates 1,25-dihydroxyvitamin D3 signaling via vitamin D receptor deacetylation

The hormonal metabolite of vitamin D, 1,25-dihydroxyvitamin D₃ (1,25D), binds to the vitamin D receptor (VDR) and promotes heterodimerization of VDR with a retinoid-X-receptor (RXR) to genomically regulate diverse cellular processes. Herein, it is revealed for the first time that VDR is post-translationally acetylated, and that VDR immunoprecipitated from human embryonic kidney (HEK293) cells displays a dramatic decrease in acetylated receptor in the presence of 1,25D-ligand, sirtuin-1 (SIRT1) deacetylase, or the resveratrol activator of SIRT1. To elucidate the functional significance of VDR deacetylation, vitamin-d-responsive-element (VDRE)-based transcriptional assays were performed to determine if deacetylase overexpression affects VDR/VDRE-driven transcription. In HEK293 kidney and TE85 bone cells, co-transfection of low amounts (1-5ng) of a SIRT1-expression vector elicits a reproducible and statistically significant enhancement (1.3- to 2.6-fold) in transcription mediated by VDREs from the CYP3A4 and cyp24a1 genes, where the magnitude of response to 1,25D-ligand is 6- to 30-fold. Inhibition of SIRT1 via EX-527, or utilization of a SIRT1 loss-of-function mutant (H363Y), resulted in abrogation of SIRT1-mediated VDR potentiation. Studies with a novel, non-acetylatable VDR mutant (K413R) showed that the mutant VDR possesses enhanced responsiveness to 1,25D, in conjunction with reduced, but still significant, sensitivity to exogenous SIRT1, indicating that acetylation of lysine 413 is relevant, but that other acetylated residues in VDR contribute to modulation of its activity. We conclude that the acetylation of VDR comprises a negative feedback loop that attenuates 1,25D-VDR signaling. This regulatory loop is reversed by SIRT1-catalyzed deacetylation of VDR to amplify VDR signaling and 1,25D actions.

Endothelin-1, α-Klotho, 25(OH) Vit D levels and severity of disease in scleroderma patients

Considering the role of endothelin-1 (ET-1) in tissue remodeling and fibrosis during the development of scleroderma as well as the effect of α-Klotho in pathogenesis of calcinosis and/or endothelial cell injury and its correlation with severity of disease, this study aimed to evaluate serum ET-1, α-Klotho and 25(OH) vitamin D levels in patients with limited and diffuse scleroderma compared to healthy subjects. In this cross-sectional study, 60 scleroderma patients according to the ACR/EULAR 2013 criteria and 60 age- and sex-matched healthy controls were included. In patients, clinical examination was performed and Medsger severity scale was assessed. Serum ET-1, soluble α-Klotho and 25(OH)D₃ levels were measured using ELISA kits. The mean ± SD age of patients and controls was 46.2 ± 9.6 and 47.2 ± 7.0 years, respectively. Compared to healthy controls, serum ET-1 was significantly higher in SSc patients (p = 0.001); whilst serum α-Klotho and 25(OH)D₃ were significantly lower in patients (p = 0.001). The most common organs involved in patients were skin, lung, peripheral vascular and gastrointestinal system and the severity of involvement was mainly mild and/or moderate. There were no significant differences in serum ET-1 and α-Klotho levels according to the severity of different organ involvement (p > 0.05). There was no significant correlation between presence or absence of calcinosis and negative or positivity of auto-antibodies with ET-1, α-Klotho and 25(OH)D₃ levels. Although our study revealed higher serum ET-1 and lower serum α-Klotho levels in SSc patients compared to healthy controls, there were not any significant correlations between their serum levels with severity of organ involvement.

Role of Vitamin D in Amyloid clearance via LRP-1 upregulation in Alzheimer's disease: A potential therapeutic target?

Amyloid beta (Aβ) deposition is considered to be one of the primary reason to trigger Alzheimer's disease (AD). Literature clearly suggests decline in Aβ clearance to be accountable for progression of late onset AD as compared to augmented Aβ production. There may be several pathways for Aβ clearance out of which one of the major pathway is the vascular-mediated removal of Aβ from the brain across the blood-brain barrier (BBB) via efflux pumps or receptors. Among Aβ scavenger receptors, low density lipoprotein receptor related protein (LRP-1) has been most extensively studied. LRP-1, is highly expressed in neurons and located on abluminal side of the brain capillaries whose expression decreases in AD patients which give rise to increased cerebral Aβ deposition. Recent evidences reveal that post 1,25-(OH)₂D₃ treatment, LRP1 expression increases significantly for both in-vivo and in-vitro studies, since Vitamin D receptors (VDR) are broadly expressed in brain. Biological actions of Vitamin D are mediated via its nuclear hormone receptor vitamin D receptor (VDR) and is found to regulate many genes. Several lines of evidence suggest that VDR deficiency/inhibition can be a potential risk factor for AD and sufficient Vitamin D supplementation is beneficial to prevent AD onset/pathology or slow down the progression of disease. The present review establishes a strong correlation between Vitamin D and LRP-1 and their possible involvement in Aβ clearance and thereby emerging as new therapeutic target.

The role of vitamin D supplementation on erectile function

In the last few years growing evidence highlighted vitamin D (VD) deficiency is one of the several dynamics that associates with increased atherosclerotic cardiovascular (ASCV) diseases. ASCV diseases and erectile dysfunction (ED) share common risk factors such as diabetes mellitus, hypertension, smoking, hyperlipidemia, and a sedentary lifestyle. The aim of this review was to summarize current progress in VD research by focusing effect of low VD level on different body systems and erectile function. Here we examine research linking VD deficiency and ED and discuss how VD influences ED and its classic risk factors that also associate to increased ED risk. We also summarize research indicating that VD associates with reduced risk of several nonvascular contributing factors for ED. Available literature demonstrates relatively high rates of low VD serum levels in ED patients. Based on the preclinical and clinical data available in the literature, to date, we infer that VD play a critical role in maintaining erectile function in humans. Nevertheless, this should also be tested through randomized controlled studies on the effect of VD supplementation with larger population.