Nongenomic Activities of Vitamin D

Interplay of calcium, vitamin D, and parathormone in the milieu of infections and immunity: Reassessed in the context of COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is recognized for inducing severe respiratory symptoms like cough, and shortness of breathing. Although symptom severity varies, some individuals remain asymptomatic. This virus has sparked a global pandemic, imposing a substantial rate of mortality or morbidity, with extended periods of illness reported. People with underlying medical issues and the elderly are more likely to experience adverse results. The virus's frequent mutations pose challenges for medical professionals, necessitating adaptable therapeutic and preventive strategies. Vitamin D, a versatile regulatory molecule, not only influences physiological processes such as serum calcium regulation but also exhibits immunomodulatory functions. Calcium ions play a crucial role as secondary signal transduction molecules, impacting diverse cellular functions and maintaining homeostasis through ion channel regulation. Parathormone, another key regulator of serum calcium, often acts antagonistically to vitamin D. This review delves into the interplay of vitamin D, calcium, and parathormone, exploring their possible influence on the progression of COVID-19. The intricate signaling involving these elements contributes to adverse prognosis, emphasizing the need for comprehensive understanding. Monitoring and controlling these physiological factors and associated pathways have shown the potential to alter disease outcomes, underscoring the importance of a holistic approach.

Biological Effects of CYP11A1-Derived Vitamin D and Lumisterol Metabolites in the Skin

Novel pathways of vitamin D3, lumisterol 3 (L3), and tachysterol 3 (T3) activation have been discovered, initiated by CYP11A1 and/or CYP27A1 in the case of L3 and T3. The resulting hydroxymetabolites enhance protection of skin against DNA damage and oxidative stress; stimulate keratinocyte differentiation; exert anti-inflammatory, antifibrogenic, and anticancer activities; and inhibit cell proliferation in a structure-dependent manner. They act on nuclear receptors, including vitamin D receptor, aryl hydrocarbon receptor, LXRα/β, RAR-related orphan receptor α/γ, and peroxisome proliferator-activated receptor-γ, with selectivity defined by their core structure and distribution of hydroxyl groups. They can activate NRF2 and p53 and inhibit NF-κB, IL-17, Shh, and Wnt/β-catenin signaling. Thus, they protect skin integrity and physiology.

Association of adiposity, serum vitamin D, and dietary quality with cardiometabolic risk factors in children aged 6-12 years: findings from SEANUTS II Malaysia

Increased cardiometabolic risk among children is increasingly becoming a concern, with evidence indicating that obesity, diet, and serum 25-hydroxyvitamin D (25(OH)D) are associated with cardiometabolic risk. However, such studies among Malaysian children are scarce. Thus, this study explores the associations between adiposity, dietary quality, and 25(OH)D, with cardiometabolic risk factors among Malaysian children aged 4-12 years. Data of 479 children (mean age: 8.2 ± 2.3 years old, 52% females) from the South East Asian Nutrition Surveys (SEANUTS II) Malaysia, were included in this analysis. Adiposity (percentage of body fat) was assessed with bioelectrical impedance technique. Dietary quality was assessed using 24 h dietary recall and calculated as mean adequacy ratio. Vitamin D was assessed based on serum 25-hydroxyvitamin D (25(OH)D). Measurements of cardiometabolic risk factors included waist circumference (WC), mean arterial pressure (MAP), fasting blood glucose (FBG), high-density lipoprotein (HDL), triglyceride, and high-sensitivity C-reactive protein, and cardiometabolic risk cluster score (siMS) was calculated. Overall, higher adiposity was positively associated with all cardiometabolic risk factors (WC, ß = 0.907; 95% CI = 0.865, 0.948; MAP, ß = 0.225; 95% CI = 0.158, 0.292; HDL, ß = -0.011; 95% CI = -0.014, -0.009; Triglyceride, ß = 0.012; 95% CI = 0.009, 0.016; FBG, ß = 0.006; 95% CI = 0.002, 0.011) and siMS score (ß = 0.033; 95% CI = 0.029, 0.037). Serum 25(OH)D was inversely associated with siMS score (ß = -0.002; 95% CI = -0.004, -0.000008) and positively associated with HDL (ß = 0.002; 95% CI = 0.0001, 0.003). Our findings suggest that adiposity is a key determinant of adverse cardiometabolic risk factors in children, while serum 25(OH)D may be associated with overall cardiometabolic health. Interventions to reduce obesity are needed to mitigate the deleterious consequences of cardiometabolic dysregulation in children.

Multifaceted Roles of Vitamin D for Diabetes: From Immunomodulatory Functions to Metabolic Regulations

Numerous studies have established associations between vitamin D and diabetes. The vitamin D receptor is widely distributed throughout the human body, including in pancreatic beta cells (β-cells), hepatocytes, and immune cells. Therefore, vitamin D's effect on the risk, progression, or complications of diabetes may be mediated through various mechanisms. These include the regulation of insulin secretion or sensitivity and modulation of β-cell function and its immunomodulatory and anti-inflammatory effects. This review extensively explores the relationship between vitamin D status and diabetes, as well as the preventive or therapeutic effects of vitamin D supplementation on diabetes from human studies. Additionally, it examines in detail the impact of vitamin D on immune and inflammatory responses in the diabetic milieux and β-cell function to better understand the underlying mechanisms through which vitamin D influences diabetes.

The PDIA3-STAT3 protein complex regulates IBS formation and development via CTSS/MHC-II pathway-mediated intestinal inflammation

Irritable bowel syndrome (IBS) is a persistent functional gastrointestinal disorder characterised by abdominal pain and altered patterns of defecation. This study aims to clarify an increase in the expression and interaction of protein disulfide-isomerase A3 (PDIA3) and Signal Transducer and Activator of Transcription 3 (STAT3) within the membrane of dendritic cells (DCs) from individuals with IBS. Mechanistically, the heightened interaction between PDIA3 and STAT3 at the DC membrane results in reduced translocation of phosphorylated STAT3 (p-STAT3) into the nucleus. The reduction of p-STAT3 to nuclear transport subsequently increased the levels of cathepsin S (CTSS) and major histocompatibility complex class II (MHC-II). Consequently, activated DCs promote CD4+ T cell proliferation and cytokine secretion, including interleukin-4 (IL-4), interleukin-6 (IL-6), interleukin-9 (IL-9), and tumour necrosis factor-alpha (TNF-α), thereby contributing to the development of IBS. Importantly, the downregulation of PDIA3 and the administration of punicalagin (Pun), a crucial active compound found in pomegranate peel, alleviate IBS symptoms in rats, such as increased visceral hypersensitivity and abnormal stool characteristics. Collectively, these findings highlight the involvement of the PDIA3-STAT3 protein complex in IBS, providing a novel perspective on the modulation of immune and inflammatory responses. Additionally, this research advances our understanding of the role and mechanisms of PDIA3 inhibitors, presenting new therapeutic possibilities for managing IBS.

Recent Advances in the Use of Vitamin D Organic Nanocarriers for Drug Delivery

Nanotechnology, now established as a transformative technology, has revolutionized medicine by enabling highly targeted drug delivery. The use of organic nanocarriers in drug delivery systems significantly enhances the bioavailability of vitamins and their analogs, thereby improving cellular delivery and therapeutic effects. Vitamin D, known for its crucial role in bone health, also influences various metabolic functions, such as cellular proliferation, differentiation, and immunomodulation, and is increasingly explored for its anticancer potential. Given its versatile properties and biocompatibility, vitamin D is an attractive candidate for encapsulation within drug delivery systems. This review provides a comprehensive overview of vitamin D synthesis, metabolism, and signaling, as well as its applications in customized drug delivery. Moreover, it examines the design and engineering of organic nanocarriers that incorporate vitamin D and discusses advances in this field, including the synergistic effects achieved through the combination of vitamin D with other therapeutic agents. By highlighting these innovations, this review provides valuable insights into the development of advanced drug delivery systems and their potential to enhance therapeutic outcomes.

Suppressing ERp57 diminishes osteoclast activity and ameliorates ovariectomy-induced bone loss via the intervention in calcium oscillation and the calmodulin/calcineurin/Nfatc1 pathway

Background

Increased osteoclast activity constitutes the primary etiology of excessive bone erosion in postmenopausal osteoporosis. ERp57, otherwise referred to as protein disulfide isomerase A3 (PDIA3), plays a crucial role in the regulation of intracellular calcium signaling. This is documented to exert a profound impact on osteoclast differentiation and functionality.

Methods

To ascertain the potential role of ERp57 in disease progression, prevention, and treatment, network pharmacology and bioinformatics analyses were conducted in relation to postmenopausal osteoporosis and ERp57 inhibitor (Loc14). Then, subsequent experimental verifications were employed in vitro on osteoclast and osteoblast, and in vivo on ovariectomy (OVX) mice models.

Results

Multiple enrichment analyses suggested that the "calcium signaling pathway" may constitute a potential avenue for therapeutic intervention by Loc14 in the treatment of postmenopausal osteoporosis. In vitro experiments demonstrated inhibition of ERp57 could block osteoclast differentiation and function by interfering with the expression of osteoclast marker genes (Traf6, Nfatc1, and Ctsk). Further mechanisms studies based on calcium imaging, qPCR, and WB established that ERp57 inhibitor (Loc14) could obstruct calcium oscillation in osteoclast precursor cells (OPCs) by limiting the entry sources of cytosolic Ca2+ and interfering with calmodulin/calcineurin/Nfatc1 pathway. Evidence from Micro-CT scanning and double calcein labeling confirmed that the application of Loc14 in vivo could alleviate bone loss and partially reversed the osteogenic impairment caused by OVX in mice.

Conclusions

Our findings proved the suppressive effects of Loc14 on osteoclastogenesis via attenuating calcium oscillation and associated singling pathways, providing ERp57 as a potential therapeutic target for postmenopausal osteoporosis.

Cholecalciferol Supplementation Impacts Behavior and Hippocampal Neuroglial Reorganization in Vitamin D-Deficient Rats

Vitamin D deficiency (VDD) is widespread around the world and has been extensively documented to affect various health conditions, including the cognitive functioning of the brain. Serum 25-hydroxylated forms of vitamin D are traditionally used to determine vitamin D status. However, there is now evidence that cholecalciferol activation can occur and be controlled by locally expressed enzymes in the brain. This study aimed to investigate the effects of cholecalciferol supplementation on cognitive function in rats who underwent transient VDD in adulthood. Thirty-six adult Wistar rats were administered paricalcitol (seven doses of 32 ng injected every other day) along with a "vitamin D-free" diet to induce VDD, which was confirmed using a LC-MS/MS serum analysis of the cholecalciferol and 25-hydroxyvitamin D3 levels. Treatment was performed by including 1000 IU/kg and 10,000 IU/kg cholecalciferol in the diet. Cognitive performance was evaluated using the novel object recognition (NOR), Morris water maze (MWM), and radial arm maze (RAM) tests. An immunohistochemical analysis of the brain regions involved in learning and memory was performed by quantifying the neurons, astrocytes, and microglia labelled with anti-neuronal nuclei (NeuN), glial fibrillary acidic protein (GFAP), and ionized calcium-binding adaptor molecule 1 (Iba-1) antibodies, respectively. The vitamin D deficient group showed the lowest performance in both the MWM and RAM tests. In contrast, the cholecalciferol-treated groups exhibited a faster learning curve. However, no difference was detected between the groups in the NOR test. On the other hand, differences in the cellular organization of the hippocampus and amygdala were observed between the groups. Cholecalciferol supplementation decreased the density of the Iba-1- and GFAP-labeled cells in the hilus and cornu Ammonis 3 (CA3) regions of the hippocampus and in the amygdala. These results support vitamin D's substantial role in learning and memory. They also highlight that subtle changes of cognitive function induced by transient VDD could be reversed by cholecalciferol supplementation. Further studies are needed to better understand VDD and cholecalciferol's effects on the brain structure and function.

Genomic and non-genomic action of vitamin D on ion channels - Targeting mitochondria

Recent studies revealed that mitochondria are not only a place of vitamin D3 metabolism but also direct or indirect targets of its activities. This review summarizes current knowledge on the regulation of ion channels from plasma and mitochondrial membranes by the active form of vitamin D3 (1,25(OH)2D3). 1,25(OH)2D3, is a naturally occurring hormone with pleiotropic activities; implicated in the modulation of cell differentiation, and proliferation and in the prevention of various diseases, including cancer. Many experimental data indicate that 1,25(OH)2D3 deficiency induces ionic remodeling and 1,25(OH)2D3 regulates the activity of multiple ion channels. There are two main theories on how 1,25(OH)2D3 can modify the function of ion channels. First, describes the involvement of genomic pathways of response to 1,25(OH)2D3 in the regulation of the expression of the genes encoding channels, their auxiliary subunits, or additional regulators. Interestingly, intracellular ion channels, like mitochondrial, are encoded by the same genes as plasma membrane channels. Therefore, the comprehensive genomic regulation of the channels from these two different cellular compartments we analyzed using a bioinformatic approach. The second theory explores non-genomic pathways of vitamin D3 activities. It was shown, that 1,25(OH)2D3 indirectly regulates enzymes that impact ion channels, change membrane physical properties, or directly bind to channel proteins. In this article, the involvement of genomic and non-genomic pathways regulated by 1,25(OH)2D3 in the modulation of the levels and activity of plasma membrane and mitochondrial ion channels was investigated by an extensive review of the literature and analysis of the transcriptomic data using bioinformatics.

From 7-dehydrocholesterol to vitamin D3: Optimization of UV conversion procedures toward the valorization of fish waste matrices

Vitamin D, a fat-soluble steroid, has increasingly taken a central role due to its crucial role in human health. It is estimated that about 40% of worldwide population are vitamin D deficient. The fish industry produces significant quantities of waste daily, with consequent high environmental impact. The aim of this work is to place a first brick for the fish waste reuse as a source of vitamin D3 extracts to be used for nutraceutical purposes. For this purpose, an UV conversion method for transforming the 7-dehydrocholesterol, highly present in fish, in vitamin D3 has been optimized. The UV wavelength, exposure time, temperature, stirring, and UV intensity were optimized using a surface response design tool. The optimized treatment was applied to five fish species with different fat percentages and the results were very promising reaching vitamin D3 levels >10 times higher than the pre-treatment ones.

Effects of vitamin D signaling in cardiovascular disease: centrality of macrophage polarization

Among the leading causes of natural death are cardiovascular diseases, cancer, and respiratory diseases. Factors causing illness include genetic predisposition, aging, stress, chronic inflammation, environmental factors, declining autophagy, and endocrine abnormalities including insufficient vitamin D levels. Inconclusive clinical outcomes of vitamin D supplements in cardiovascular diseases demonstrate the need to identify cause-effect relationships without bias. We employed a spectral clustering methodology capable of analyzing large diverse datasets for examining the role of vitamin D's genomic and non-genomic signaling in disease in this study. The results of this investigation showed the following: (1) vitamin D regulates multiple reciprocal feedback loops including p53, macrophage autophagy, nitric oxide, and redox-signaling; (2) these regulatory schemes are involved in over 2,000 diseases. Furthermore, the balance between genomic and non-genomic signaling by vitamin D affects autophagy regulation of macrophage polarization in tissue homeostasis. These findings provide a deeper understanding of how interactions between genomic and non-genomic signaling affect vitamin D pharmacology and offer opportunities for increasing the efficacy of vitamin D-centered treatment of cardiovascular disease and healthy lifespans.

Malignant Melanoma: An Overview, New Perspectives, and Vitamin D Signaling

Melanoma, originating through malignant transformation of melanin-producing melanocytes, is a formidable malignancy, characterized by local invasiveness, recurrence, early metastasis, resistance to therapy, and a high mortality rate. This review discusses etiologic and risk factors for melanoma, diagnostic and prognostic tools, including recent advances in molecular biology, omics, and bioinformatics, and provides an overview of its therapy. Since the incidence of melanoma is rising and mortality remains unacceptably high, we discuss its inherent properties, including melanogenesis, that make this disease resilient to treatment and propose to use AI to solve the above complex and multidimensional problems. We provide an overview on vitamin D and its anticancerogenic properties, and report recent advances in this field that can provide solutions for the prevention and/or therapy of melanoma. Experimental papers and clinicopathological studies on the role of vitamin D status and signaling pathways initiated by its active metabolites in melanoma prognosis and therapy are reviewed. We conclude that vitamin D signaling, defined by specific nuclear receptors and selective activation by specific vitamin D hydroxyderivatives, can provide a benefit for new or existing therapeutic approaches. We propose to target vitamin D signaling with the use of computational biology and AI tools to provide a solution to the melanoma problem.

The Importance of Nutrigenetics and Microbiota in Personalized Medicine: From Phenotype to Genotype

Background After the completion of the Human Genome Project in 2003, the impact of genetic variations among people on human health was better understood. Precision medicine, also called 4P (Predictive, Preventive, Personalized, Participatory) medicine, is used to determine personal health risks, prevent, diagnose, and treat chronic diseases, and aims to identify the phenotypic, genotypic, and environmental factors that affect individual health risks instead of applying the same approach to everyone. Methods The study was conducted with 24 patients aged between 7 and 57. The patient group was selected from individuals who had undergone genetic and microbiota testing at Epigenetic Coaching Company. The patients' age, gender, and health status were documented. Genomic analysis of buccal samples was subsequently conducted using a custom Infinium HTS iSelect microarray on an Illumina iScan instrument, and microbiota metagenome analysis was performed using an Illumina NextSeq 500 platform. This study was performed in line with the principles of the Declaration of Helsinki. Approval was granted by the Ethics Committee of Biruni University Molecular Biology and Genetics Ethics Committee, with the decision number 2023/78-03. Results The genotypes of 19 cases carrying genetic variants involved in the metabolism of Vitamin D, Folate, B12, and Choline were analyzed. Eight of the cases were included in our study as autism patients, eight as allergy patients, and three as autoimmune thyroiditis patients. The Vitamin D receptor (VDR) genetic variants and microbiota diversity (using the Firmicutes/Bacteroides ratio, an indicator of dysbiosis) of 11 cases (9 allergy and two autism patients) participating in the study were evaluated together. Conclusions Translating nutrigenetic and nutrigenomic research into multidisciplinary clinical practice is the most challenging aspect. It is now evident that integrating data regarding phenotype and genotype, and using nutrition, lifestyle, and supplements tailored to an individual's genetics can increase clinical success. Importantly, if we wish to adopt an epigenomic approach, we must incorporate analyses of nutrigenetics, microbiota, and personalized risk based on test results.

Vitamin D deficiency or resistance and hypophosphatemia

Vitamin D is mainly produced in the skin (cholecalciferol) by sun exposure while a fraction of it is obtained from dietary sources (ergocalciferol). Vitamin D is further processed to 25-hydroxyvitamin D and 1,25-dihydroxy vitamin D (calcitriol) in the liver and kidneys, respectively. Calcitriol is the active form which mediates the actions of vitamin D via vitamin D receptor (VDR) which is present ubiquitously. Defect at any level in this pathway leads to vitamin D deficient or resistant rickets. Nutritional vitamin D deficiency is the leading cause of rickets and osteomalacia worldwide and responds well to vitamin D supplementation. Inherited disorders of vitamin D metabolism (vitamin D-dependent rickets, VDDR) account for a small proportion of calcipenic rickets/osteomalacia. Defective 1α hydroxylation of vitamin D, 25 hydroxylation of vitamin D, and vitamin D receptor result in VDDR1A, VDDR1B and VDDR2A, respectively whereas defective binding of vitamin D to vitamin D response element due to overexpression of heterogeneous nuclear ribonucleoprotein and accelerated vitamin D metabolism cause VDDR2B and VDDR3, respectively. Impaired dietary calcium absorption and consequent calcium deficiency increases parathyroid hormone in these disorders resulting in phosphaturia and hypophosphatemia. Hypophosphatemia is a common feature of all these disorders, though not a sine-qua-non and leads to hypomineralisation of the bone and myopathy. Improvement in hypophosphatemia is one of the earliest markers of response to vitamin D supplementation in nutritional rickets/osteomalacia and the lack of such a response should prompt evaluation for inherited forms of rickets/osteomalacia.

Dissection of an impact of VDR and RXRA on the genomic activity of 1,25(OH)2D3 in A431 squamous cell carcinoma

BACKGROUND

Human skin is the natural source, place of metabolism, and target for vitamin D3. The classical active form of vitamin D3, 1,25(OH)2D3, expresses pluripotent properties and is intensively studied in cancer prevention and therapy. To define the specific role of vitamin D3 receptor (VDR) and its co-receptor retinoid X receptor alpha (RXRA) in genomic regulation, VDR or RXRA genes were silenced in the squamous cell carcinoma cell line A431 and treated with 1,25(OH)2D3 at long incubation time points 24 h/72 h. Extending the incubation time of A431 WT (wild-type) cells with 1,25(OH)2D3 resulted in a two-fold increase in DEGs (differentially expressed genes) and a change in the amount of downregulated from 37% to 53%. VDR knockout led to a complete loss of 1,25(OH)2D3-induced genome-wide gene regulation at 24 h time point, but after 72 h, 20 DEGs were found, of which 75% were downregulated, and most of them belonged to the gene ontology group "immune response". This may indicate the existence of an alternative, secondary response to 1,25(OH)2D3. In contrast, treatment of A431 ΔRXRA cells with 1,25(OH)2D3 for 24 h only partially affected DEGs, suggesting RXRA-independent regulation. Interestingly, overexpression of classic 1,25(OH)2D3 targets, like CYP24A1 (family 24 of subfamily A of cytochrome P450 member 1) or CAMP (cathelicidin antimicrobial peptide) was found to be RXRA-independent. Also, immunofluorescence staining of A431 WT cells revealed partial VDR/RXRA colocalization after 24 h and 72 h 1,25(OH)2D3 treatment. Comparison of transcriptome changes induced by 1,25(OH)2D3 in normal keratinocytes vs. cancer cells showed high cell type specific expression pattern with only a few genes commonly regulated by 1,25(OH)2D3. Activation of the genomic pathway at least partially reversed the expression of cancer-related genes, forming a basis for anti-cancer activates of 1,25(OH)2D3. In summary, VDR or RXRA independent genomic activities of 1,25(OH)2D3 suggest the involvement of alternative factors, opening new challenges in this field.

Vitamin D nutritional status in early pregnancy and its relationship with periconceptional multiple micronutrients supplementation

BACKGROUND AND OBJECTIVES

To assess the vitamin D nutritional status (VDN) of pregnant women in early pregnancy and investigate the effects of periconceptional supplementation with multiple micronutrients (MMs) on this status.

METHODS AND STUDY DESIGN

Data were taken from the Pregnancy Health Care System and Hospital Information System in 2018 in Beijing. Vitamin D nutritional status in early pregnancy was evaluated among 4,978 pregnant women, and 4,540 women who took folic acid only (FA) or multiple mi-cronutrients supplements (MM) during the periconceptional period, were include to estimate the associations between periconceptional supplementation with MM and prevalence of vitamin D deficiency or insufficiency with logistic regression model.

RESULTS

The mean early-pregnancy vitamin D concentration was 18.6 (±7.5) ng/mL, and the rates of deficiency and insufficiency were 31.6% and 60.5%, respectively. Compared to the FA group, the adjusted odds ratio (aOR, 95%confidence interval, CI) for insufficiency or deficiency of the MM group were 0.25(0.18-0.34), and the aOR (95%CI) for deficiency of the MM group were 0.17 (0.12-0.23). Women who took MMs for a longer period of time, at higher frequencies, and with higher compliance scores had lower rates of deficiency and insufficiency. In winter, spring, and autumn, taking MMs could reduce deficiency by about 70%; in summer, there was little effect.

CONCLUSIONS

Among women in Beijing, serum concentrations of vitamin D in early pregnancy are relatively low, and the rates of deficiency and insufficiency are high. Taking MMs during the periconceptional period could improve this situation.

Retrospective Analysis of Vitamin D Deficiency in an Adult Population of Arad County, Western Romania (2019-2022)

Vitamin D, a steroid hormone synthesized primarily in the skin upon exposure to ultraviolet light, is widely deficient across global populations. This study aimed to fill the data gap in Western Romania by measuring 25-hydroxy-vitamin D levels in a cohort of 7141 from Arad County. It was observed that women, younger adults (18-29 years), and older adults (70-79 years) had notably lower vitamin D levels compared to the average population. Additionally, there was a rise in vitamin D levels over the four-year span of 2018-2022, coinciding with the COVID-19 pandemic. Our research provides fresh data on those most susceptible to vitamin D deficiency and lays the groundwork for educational campaigns on vitamin D supplementation benefits.

1,25-dihydroxyvitamin D3 affects thapsigargin-induced endoplasmic reticulum stress in 3T3-L1 adipocytes

BACKGROUND/OBJECTIVES

Endoplasmic reticulum (ER) stress in adipose tissue causes an inflammatory response and leads to metabolic diseases. However, the association between vitamin D and adipose ER stress remains poorly understood. In this study, we investigated whether 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) alleviates ER stress in adipocytes.

MATERIALS/METHODS

3T3-L1 cells were treated with different concentrations (i.e., 10-100 nM) of 1,25(OH)2D3 after or during differentiation (i.e., on day 0-7, 3-7, or 7). They were then incubated with thapsigargin (TG, 500 nM) for an additional 24 h to induce ER stress. Next, we measured the mRNA and protein levels of genes involved in unfold protein response (UPR) and adipogenesis using real-time polymerase chain reaction and western blotting and quantified the secreted protein levels of pro-inflammatory cytokines. Finally, the mRNA levels of UPR pathway genes were measured in adipocytes transfected with siRNA-targeting Vdr.

RESULTS

Treatment with 1,25(OH)2D3 during various stages of adipocyte differentiation significantly inhibited ER stress induced by TG. In fully differentiated 3T3-L1 adipocytes, 1,25(OH)2D3 treatment suppressed mRNA levels of Ddit3, sXbp1, and Atf4 and decreased the secretion of monocyte chemoattractant protein-1, interleukin-6, and tumor necrosis factor-α. However, downregulation of the mRNA levels of Ddit3, sXbp1, and Atf4 following 1,25(OH)2D3 administration was not observed in Vdr-knockdown adipocytes. In addition, exposure of 3T3-L1 preadipocytes to 1,25(OH)2D3 inhibited transcription of Ddit3, sXbp1, Atf4, Bip, and Atf6 and reduced the p-alpha subunit of translation initiation factor 2 (eIF2α)/eIF2α and p-protein kinase RNA-like ER kinase (PERK)/PERK protein ratios. Furthermore, 1,25(OH)2D3 treatment before adipocyte differentiation reduced adipogenesis and the mRNA levels of adipogenic genes.

CONCLUSIONS

Our data suggest that 1,25(OH)2D3 prevents TG-induced ER stress and inflammatory responses in mature adipocytes by downregulating UPR signaling via binding with Vdr. In addition, the inhibition of adipogenesis by vitamin D may contribute to the reduction of ER stress in adipocytes.

Ukrainian Consensus on Diagnosis and Management of Vitamin D Deficiency in Adults

Vitamin D deficiency (VDD) is a global problem, however, there were no Ukrainian guidelines devoted to its screening, prevention, and treatment, which became the reason for the Consensus creation. This article aimed to present the Consensus of Ukrainian experts devoted to VDD management. Following the creation of the multidisciplinary Consensus group, consent on the formation process, drafting and fine-tuning of key recommendations, and two rounds of voting, 14 final recommendations were successfully voted upon. Despite a recent decrease in VDD prevalence in Ukraine, we recommend raising awareness regarding VDD's importance and improving the strategies for its decline. We recommend screening the serum 25-hydroxyvitamin D (25(OH)D) level in risk groups while maintaining a target concentration of 75-125 nmol/L (30-50 ng/mL). We recommend prophylactic cholecalciferol supplementation (800-2000 IU/d for youthful healthy subjects, and 3000-5000 IU/d for subjects from the risk groups). For a VDD treatment, we recommend a short-term administration of increased doses of cholecalciferol (4000-10,000 IU/d) with 25(OH)D levels monitored after 4-12 weeks of treatment, followed by the use of maintenance doses. Additionally, we recommend assessing serum 25(OH)D levels before antiosteoporotic treatment and providing vitamin D and calcium supplementation throughout the full course of the antiosteoporotic therapy.

Different impact of vitamin D on mitochondrial activity and morphology in normal and malignant keratinocytes, the role of genomic pathway

Deregulation of mitochondria activity is one of the hallmarks of cancerogenesis and an important target for cancer therapy. Therefore, we compared the impact of an active form of vitamin D3 (1,25(OH)2D3) on mitochondrial morphology and bioenergetics in human squamous cell carcinoma (A431) and immortalized HaCaT keratinocytes. It was shown that mitochondria of cancerous A431 cells differ from that observed in HaCaT keratinocytes in terms of network, morphology, bioenergetics, glycolysis, and mitochondrial DNA copy number, while treatment of A431 with 1,25(OH)2D3 partially eliminates these differences. Furthermore, mitochondrial membrane potential, basal respiration, and mitochondrial reactive oxygen species production were decreased in A431 cells treated with 1,25(OH)2D3. Additionally, the expression and protein level of mitophagy marker PINK1 was significantly increased in A431 1,25(OH)2D3 treated cells, but not observed in treated HaCaT cells. Knockout of VDR (vitamin D receptor) or RXRA (binding partner retinoid X receptor) partially altered mitochondrial morphology and function as well as mitochondrial response to 1,25(OH)2D3. Transcriptomic analysis on A431 cells treated with 1,25(OH)2D3 revealed modulation of expression of several mitochondrial-related genes involved in mitochondrial depolarization, mitochondrial protein translation (i.e. LYRM9, MARS2), and fusion-fission (OPA1, FIS1, MFN1 and 2), however, none of the genes coded by mitochondrial DNA was affected. Interestingly, in silico analyses of nuclear-encoded mitochondrial genes revealed that they are rather activated by the secondary genomic response to 1,25(OH)2D3. Taken together, 1,25(OH)2D3 remodels mitochondrial architecture and bioenergetics through VDR-dependent and only partially RXRA-dependent activation of the genomic pathway, thus outlining a new perspective for anticancer properties of vitamin D3 in relation to mitochondria in squamous cell carcinoma.

Vitamin D as a Modulator of Neuroinflammation: Implications for Brain Health

Neuroinflammation represents a critical immune response within the brain, playing a pivotal role in defense against injury and infection. However, when this response becomes chronic, it can contribute to the development of various neurodegenerative and psychiatric disorders. This bibliographic review delves into the role of vitamin D in modulating neuroinflammation and its implications for brain health, particularly in the context of neurological and psychiatric disorders. While vitamin D is traditionally associated with calcium homeostasis and bone health, it also exerts immunomodulatory and neuroprotective effects within the central nervous system. Through comprehensive analysis of preclinical and clinical studies, we uncover how vitamin D, acting through its receptors in glial cells, may influence the production of proinflammatory cytokines and antioxidants, potentially mitigating the cascade of events leading to neuronal damage. Clinical research has identified vitamin D deficiency as a common thread in the increased risks of multiple sclerosis, Parkinson's disease, Alzheimer's, and depression, among others. Furthermore, preclinical models suggest vitamin D's regulatory capacity over inflammatory mediators, its protective role against neuronal apoptosis, and its contribution to neurogenesis and synaptic plasticity. These insights underscore the potential of vitamin D supplementation not only in slowing the progression of neurodegenerative diseases but also in improving the quality of life for patients suffering from psychiatric conditions. Future clinical studies are essential to validate these findings and further our understanding of vitamin D's capacity to prevent or alleviate symptoms, opening new avenues for therapeutic strategies against neuroinflammation-related pathologies. Neuroinflammation is a crucial immune response in the brain against injuries or infections, but its persistence can lead to diseases such as Alzheimer's, Parkinson's, multiple sclerosis, and depression. Cholecalciferol (Vitamin D3) emerges as a regulator of neuroinflammation, present in brain cells such as astrocytes and microglia, modulating immune function. Vitamin D's mechanisms of action include cytokine modulation and regulation of nuclear and mitochondrial genes. It adjusts inflammatory mediators and antioxidants, resulting in neuroprotective effects. Additionally, vitamin D impacts neurotransmitter synthesis and brain plasticity. This positions vitamin D as a potential adjunct in treating diseases like Alzheimer's and Parkinson's. Lastly, its role in intestinal microbiota and serotonin synthesis contributes to psychiatric disorders like schizophrenia and depression. Thus, vitamin D presents a novel therapeutic approach for neuroinflammatory, neurodegenerative, and neuropsychiatric diseases.

VDR and PDIA3 Are Essential for Activation of Calcium Signaling and Membrane Response to 1,25(OH)2D3 in Squamous Cell Carcinoma Cells

The genomic activity of 1,25(OH)2D3 is mediated by vitamin D receptor (VDR), whilst non-genomic is associated with protein disulfide isomerase family A member 3 (PDIA3). Interestingly, our recent studies documented that PDIA3 is also involved, directly or indirectly, in the modulation of genomic response to 1,25(OH)2D3. Moreover, PDIA3 was also shown to regulate cellular bioenergetics, possibly through the modulation of STAT signaling. Here, the role of VDR and PDIA3 proteins in membrane response to 1,25(OH)2D3 and calcium signaling was investigated in squamous cell carcinoma A431 cell line with or without the deletion of VDR and PDIA3 genes. Calcium influx was assayed by Fura-2AM or Fluo-4AM, while calcium-regulated element (NFAT) activation was measured using a dual luciferase assay. Further, the levels of proteins involved in membrane response to 1,25(OH)2D3 in A431 cell lines were analyzed via Western blot analysis. The deletion of either PDIA3 or VDR resulted in the decreased baseline levels of Ca2+ and its responsiveness to 1,25(OH)2D3; however, the effect was more pronounced in A431∆PDIA3. Furthermore, the knockout of either of these genes disrupted 1,25(OH)2D3-elicited membrane signaling. The data presented here indicated that the VDR is essential for the activation of calcium/calmodulin-dependent protein kinase II alpha (CAMK2A), while PDIA3 is required for 1,25(OH)2D3-induced calcium mobilization in A431 cells. Taken together, those results suggest that both VDR and PDIA3 are essential for non-genomic response to this powerful secosteroid.

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.

PDIA3 modulates genomic response to 1,25-dihydroxyvitamin D3 in squamous cell carcinoma of the skin

An active form of vitamin D3 (1,25-dihydroxyvitamin D3) acts through vitamin D receptor (VDR) initiating genomic response, but several studies described also non-genomic actions of 1,25-dihydroxyvitamin D3, implying the role of PDIA3 in the process. PDIA3 is a membrane-associated disulfide isomerase involved in disulfide bond formation, protein folding, and remodeling. Here, we used a transcriptome-based approach to identify changes in expression profiles in PDIA3-deficient squamous cell carcinoma line A431 after 1,25-dihydroxyvitamin D3 treatment. PDIA3 knockout led to changes in the expression of more than 2000 genes and modulated proliferation, cell cycle, and mobility of cells; suggesting an important regulatory role of PDIA3. PDIA3-deficient cells showed increased sensitivity to 1,25-dihydroxyvitamin D3, which led to decrease migration. 1,25-dihydroxyvitamin D3 treatment altered also genes expression profile of A431ΔPDIA3 in comparison to A431WT cells, indicating the existence of PDIA3-dependent genes. Interestingly, classic targets of VDR, including CAMP (Cathelicidin Antimicrobial Peptide), TRPV6 (Transient Receptor Potential Cation Channel Subfamily V Member 6), were regulated differently by 1,25-dihydroxyvitamin D3, in A431ΔPDIA3. Deletion of PDIA3 impaired 1,25-dihydroxyvitamin D3-response of genes, such as PTGS2, MMP12, and FOCAD, which were identified as PDIA3-dependent. Additionally, response to 1,25-dihydroxyvitamin D3 in cancerous A431 cells differed from immortalized HaCaT keratinocytes, used as non-cancerous control. Finally, silencing of PDIA3 and 1,25-dihydroxyvitamin D3, at least partially reverse the expression of cancer-related genes in A431 cells, thus targeting PDIA3 and use of 1,25-dihydroxyvitamin D3 could be considered in a prevention and therapy of the skin cancer. Taken together, PDIA3 has a strong impact on gene expression and physiology, including genomic response to 1,25-dihydroxyvitamin D3.

Protein Disulfide Isomerase Family A Member 3 Knockout Abrogate Effects of Vitamin D on Cellular Respiration and Glycolysis in Squamous Cell Carcinoma

PDIA3 is an endoplasmic reticulum disulfide isomerase, which is involved in the folding and trafficking of newly synthesized proteins. PDIA3 was also described as an alternative receptor for the active form of vitamin D (1,25(OH)2D3). Here, we investigated an impact of PDIA3 in mitochondrial morphology and bioenergetics in squamous cell carcinoma line A431 treated with 1,25(OH)2D3. It was observed that PDIA3 deletion resulted in changes in the morphology of mitochondria including a decrease in the percentage of mitochondrial section area, maximal diameter, and perimeter. The 1,25(OH)2D3 treatment of A431∆PDIA3 cells partially reversed the effect of PDIA3 deletion increasing aforementioned parameters; meanwhile, in A431WT cells, only an increase in mitochondrial section area was observed. Moreover, PDIA3 knockout affected mitochondrial bioenergetics and modulated STAT3 signaling. Oxygen consumption rate (OCR) was significantly increased, with no visible effect of 1,25(OH)2D3 treatment in A431∆PDIA3 cells. In the case of Extracellular Acidification Rate (ECAR), an increase was observed for glycolysis and glycolytic capacity parameters in the case of non-treated A431WT cells versus A431∆PDIA3 cells. The 1,25(OH)2D3 treatment had no significant effect on glycolytic parameters. Taken together, the presented results suggest that PDIA3 is strongly involved in the regulation of mitochondrial bioenergetics in cancerous cells and modulation of its response to 1,25(OH)2D3, possibly through STAT3.

Calcifediol: Mechanisms of Action

Due to its essential role in calcium and phosphate homeostasis, the secosteroid hormone calcitriol has received growing attention over the last few years. Calcitriol, like other steroid hormones, may function through both genomic and non-genomic mechanisms. In the traditional function, the interaction between the biologically active form of vitamin D and the vitamin D receptor (VDR) affects the transcription of thousands of genes by binding to repeated sequences present in their promoter region, named vitamin D-responsive elements (VDREs). Non-transcriptional effects, on the other hand, occur quickly and are unaffected by inhibitors of transcription and protein synthesis. Recently, calcifediol, the immediate precursor metabolite of calcitriol, has also been shown to bind to the VDR with weaker affinity than calcitriol, thus exerting gene-regulatory properties. Moreover, calcifediol may also trigger rapid non-genomic responses through its interaction with specific membrane vitamin D receptors. Membrane-associated VDR (mVDR) and protein disulfide isomerase family A member 3 (Pdia3) are the best-studied candidates for mediating these rapid responses to vitamin D metabolites. This paper provides an overview of the calcifediol-related mechanisms of action, which may help to better understand the vitamin D endocrine system and to identify new therapeutic targets that could be important for treating diseases closely associated with vitamin D deficiency.

Modulatory role of vitamins A, B3, C, D, and E on skin health, immunity, microbiome, and diseases

Disruption of the skin barrier and immunity has been associated with several skin diseases, namely atopic dermatitis (AD), psoriasis, and acne. Resident and non-resident immune cells and the barrier system of the skin are integral to innate immunity. Recent advances in understanding skin microbiota have opened the scope of further understanding the various communications between these microbiota and skin immune cells. Vitamins, being one of the important micronutrients, have been reported to exert antioxidant, anti-inflammatory, and anti-microbial effects. The immunomodulatory action of vitamins can halt the progression of skin diseases, and thus, understanding the immuno-pharmacology of these vitamins, especially for skin diseases can pave the way for their therapeutic potential. At the same time, molecular and cellular markers modulated with these vitamins and their derivatives need to be explored. The present review is focused on significant vitamins (vitamins A, B3, C, D, and E) consumed as nutritional supplements to discuss the outcomes and scope of studies related to skin immunity, health, and diseases.

Vitamin D and Periodontal Health: A Systematic Review

The role of vitamin D in maintaining gum well-being is crucial. However, scientific research reported that the connotations of cholecalciferol and periodontal health have been divested in the present literature. However, there is enormous heterogeneity in the data available. The current review aims to systematically review and appraise the available literature investigating the role of vitamin D in maintaining periodontal health. Studies included randomized controlled trials and clinical trials following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and cohort studies reporting associations between vitamin D and oral health in systemically healthy patients. Databases such as PubMed, Google Scholar, Scopus, Embase, and other sources, including hand search, were searched until May 2023 using together-equipped search sequences. Altogether, scientific articles that conform to the inclusion principles underwent a thorough eminence evaluation. All papers meeting inclusion criteria were subject to quality assessment, and the method used to assess the risk of bias was the Cochrane risk of bias tool. The search identified 1883 papers, among which 1435 were excluded after title evaluation. After abstract and title screening, 455 were excluded, and six full texts were assessed. After full-text evaluation, two articles were excluded, and only four were included. The data shows vitamin D's association with oral health maintenance. Along with its action on bone metabolism, it has extended function, which provides for its action as an anti-inflammatory agent and production of anti-microbial peptides, which help maintain oral health. Although the literature available is immense, there is enormous heterogenicity in the papers conducted to appraise the association between vitamin D and oral health. This systematic review has filtered all the data to review a few essential aspects of the role of vitamin D in maintaining oral physiology. Vitamin D has a linear relationship with periodontal health; however, the evidence is insufficient, and further studies must be done.

Impact of Vitamin D on Immunopathology of Hashimoto's Thyroiditis: From Theory to Practice

Hashimoto's thyroiditis (HT) is a common autoimmune disease affecting the thyroid gland, characterized by lymphocytic infiltration, damage to thyroid cells, and hypothyroidism, and often requires lifetime treatment with levothyroxine. The disease has a complex etiology, with genetic and environmental factors contributing to its development. Vitamin D deficiency has been linked to a higher prevalence of thyroid autoimmunity in certain populations, including children, adolescents, and obese individuals. Moreover, vitamin D supplementation has shown promise in reducing antithyroid antibody levels, improving thyroid function, and improving other markers of autoimmunity, such as cytokines, e.g., IP10, TNF-α, and IL-10, and the ratio of T-cell subsets, such as Th17 and Tr1. Studies suggest that by impacting various immunological mechanisms, vitamin D may help control autoimmunity and improve thyroid function and, potentially, clinical outcomes of HT patients. The article discusses the potential impact of vitamin D on various immune pathways in HT. Overall, current evidence supports the potential role of vitamin D in the prevention and management of HT, although further studies are needed to fully understand its mechanisms of action and potential therapeutic benefits.

Role of Vitamin D in Head and Neck Cancer-Immune Function, Anti-Tumour Effect, and Its Impact on Patient Prognosis

Head and neck squamous cell carcinoma (HNSCC) describes a heterogeneous group of human neoplasms of the head and neck with high rates of morbidity and mortality, constituting about 3% of all cancers and ~1.5% of all cancer deaths. HNSCC constituted the seventh most prevalent human malignancy and the most common human cancer in the world in 2020, according to multi-population observations conducted by the GLOBOCAN group. Since approximately 60-70% of patients present with stage III/IV neoplastic disease, HNSCC is still one of the leading causes of death in cancer patients worldwide, with an overall survival rate that is too low, not exceeding 40-60% of these patients. Despite the application of newer surgical techniques and the implementation of modern combined oncological treatment, the disease often follows a fatal course due to frequent nodal metastases and local neoplastic recurrences. The role of micronutrients in the initiation, development, and progression of HNSCC has been the subject of considerable research. Of particular interest has been vitamin D, the pleiotropic biologically active fat-soluble family of secosteroids (vitamin-D-like steroids), which constitutes a key regulator of bone, calcium, and phosphate homeostasis, as well as carcinogenesis and the further development of various neoplasms. Considerable evidence suggests that vitamin D plays a key role in cellular proliferation, angiogenesis, immunity, and cellular metabolism. A number of basic science, clinical, and epidemiological studies indicate that vitamin D has multidirectional biological effects and influences anti-cancer intracellular mechanisms and cancer risk, and that vitamin D dietary supplements have various prophylactic benefits. In the 20th century, it was reported that vitamin D may play various roles in the protection and regulation of normal cellular phenotypes and in cancer prevention and adjunctive therapy in various human neoplasms, including HNSCC, by regulating a number of intracellular mechanisms, including control of tumour cell expansion and differentiation, apoptosis, intercellular interactions, angio- and lymphogenesis, immune function, and tumour invasion. These regulatory properties mainly occur indirectly via epigenetic and transcriptional changes regulating the function of transcription factors, chromatin modifiers, non-coding RNA (ncRNAs), and microRNAs (miRs) through protein-protein interactions and signalling pathways. In this way, calcitriol enhances intercellular communication in cancer biology, restores the connection with the extracellular matrix, and promotes the epithelial phenotype; it thus counteracts the tumour-associated detachment from the extracellular matrix and inhibits the formation of metastases. Furthermore, the confirmation that the vitamin D receptor (VDR) is present in many human tissues confirmed the physiopathological significance of vitamin D in various human tumours. Recent studies indicate quantitative associations between exposure to vitamin D and the incidence of HNC, i.e., cancer risk assessment included circulating calcidiol plasma/serum concentrations, vitamin D intake, the presence of the VDR gene polymorphism, and genes involved in the vitamin D metabolism pathway. Moreover, the chemopreventive efficacy of vitamin D in precancerous lesions of the head and neck and their role as predictors of mortality, survival, and recurrence of head and neck cancer are also widely discussed. As such, it may be considered a promising potential anti-cancer agent for developing innovative methods of targeted therapy. The proposed review discusses in detail the mechanisms regulating the relationship between vitamin D and HNSCC. It also provides an overview of the current literature, including key opinion-forming systematic reviews as well as epidemiological, prospective, longitudinal, cross-sectional, and interventional studies based on in vitro and animal models of HNSCC, all of which are accessible via the PubMed/Medline/EMBASE/Cochrane Library databases. This article presents the data in line with increasing clinical credibility.

Physiological Basis for Using Vitamin D to Improve Health

Vitamin D is essential for life-its sufficiency improves metabolism, hormonal release, immune functions, and maintaining health. Vitamin D deficiency increases the vulnerability and severity of type 2 diabetes, metabolic syndrome, cancer, obesity, and infections. The active enzyme that generates vitamin D [calcitriol: 1,25(OH)₂D], CYP27B1 (1α-hydoxylase), and its receptors (VDRs) are distributed ubiquitously in cells. Once calcitriol binds with VDRs, the complexes are translocated to the nucleus and interact with responsive elements, up- or down-regulating the expression of over 1200 genes and modulating metabolic and physiological functions. Administration of vitamin D₃ or correct metabolites at proper doses and frequency for longer periods would achieve the intended benefits. While various tissues have different thresholds for 25(OH)D concentrations, levels above 50 ng/mL are necessary to mitigate conditions such as infections/sepsis, cancer, and reduce premature deaths. Cholecalciferol (D₃) (not its metabolites) should be used to correct vitamin D deficiency and raise serum 25(OH)D to the target concentration. In contrast, calcifediol [25(OH)D] raises serum 25(OH)D concentrations rapidly and is the agent of choice in emergencies such as infections, for those who are in ICUs, and for insufficient hepatic 25-hydroxylase (CYP2R1) activity. In contrast, calcitriol is necessary to maintain serum-ionized calcium concentration in persons with advanced renal failure and hypoparathyroidism. Calcitriol is, however, ineffective in most other conditions, including infections, and as vitamin D replacement therapy. Considering the high costs and higher incidence of adverse effects due to narrow therapeutic margins (ED50), 1α-vitamin D analogs, such as 1α-(OH)D and 1,25(OH)₂D, should not be used for other conditions. Calcifediol analogs cost 20 times more than D₃-thus, they are not indicated as a routine vitamin D supplement for hypovitaminosis D, osteoporosis, or renal failure. Healthcare workers should resist accepting inappropriate promotions, such as calcifediol for chronic renal failure and calcitriol for osteoporosis or infections-there is no physiological rationale for doing so. Maintaining the population's vitamin D sufficiency (above 40 ng/mL) with vitamin D₃ supplements and/or daily sun exposure is the most cost-effective way to reduce chronic diseases and sepsis, overcome viral epidemics and pandemics, and reduce healthcare costs. Furthermore, vitamin D sufficiency improves overall health (hence reducing absenteeism), reduces the severity of chronic diseases such as metabolic and cardiovascular diseases and cancer, decreases all-cause mortality, and minimizes infection-related complications such as sepsis and COVID-19-related hospitalizations and deaths. Properly using vitamin D is the most cost-effective way to reduce chronic illnesses and healthcare costs: thus, it should be a part of routine clinical care.

Can Vitamin D Levels Alter the Effectiveness of Short-Term Facelift Interventions?

Facelifting is increasingly popular among the population. It exceeded the limits of post-traumatic facia-reconstruction. Both the demand and the methods available are getting increasingly diverse. The minimally invasive technique revolutionized the facelift, although it took some time to completely comprehend the mechanics. The roles of vitamin D in numerous physiological processes in which it is involved have mostly been elucidated in the last decade. Our hypothesis is based on one of these roles, that is, vitamin D intervenes in changing the type of collagen by changing its location; therefore, collagen will have a supporting role for the subcutaneous tissue. A group of 156 patients with different facelifting methods was followed: 93 minimally invasive (NC), 49 classical surgery (C) and 14 with the combined technique (NC + C). The change in the subcutaneous tissue was monitored by an elastograph. The level of vitamin D was monitored in order to assess the immediate and long-term effects of vitamin D on the progression of subcutaneous fibrosis. It was proven that an optimal level of vitamin D has a beneficial effect in maintaining the volume of subcutaneous tissue in patients from the NC and NC + C groups, the best results being in the NC + C group. An increase in the subcutaneous volume was recorded, which leads to a decrease in elasticity (statistical significance p < 0.05) and the lowering of the subcutaneous tissue, and an increased amount of lowering corresponds to a lowering of vitamin D levels.

Significance of 1,25-Dihydroxyvitamin D3 on Overall Mortality in Peritoneal Dialysis Patients with COVID-19

In previous publications, we pointed out the importance of mannosylation of fibrinogen for the development of cardiovascular complications and fucosylation as a predictor of peritoneal membrane dysfunction in patients on peritoneal dialysis (PD). After a follow-up period of 30 months from the onset of the COVID-19 pandemic, we evaluated the significance of 1,25-dihydroxyvitamin D₃ (calcitriol) therapy, primary disease, biochemical and hematologic analyzes, and previously performed glycan analysis by lectin-based microarray as predictors of mortality in this patient group. After univariate Cox regression analysis, diabetes mellitus (DM) and calcitriol therapy were found to be potential predictors of mortality. Additional multivariate Cox regression analysis confirmed that only DM was a predictor of mortality. Nevertheless, the use of calcitriol in therapy significantly reduced mortality in this patient group, as shown by the Kaplan-Meier survival curve. The presence of DM as a concomitant disease proved to be a strong predictor of fatal outcome in PD patients infected with SARS-CoV-2. This is the first study to indicate the importance and beneficial effect of calcitriol therapy on survival in PD patients with COVID-19 infection. In addition, this study points to the possibility that adverse thrombogenic events observed in PD patients during the pandemic may be caused by aberrant fibrinogen glycosylation.

Reply to Pluta, R. Comment on "Minich et al. Is Melatonin the "Next Vitamin D"?: A Review of Emerging Science, Clinical Uses, Safety, and Dietary Supplements. Nutrients 2022, 14, 3934"

We would like to thank Dr. Pluta for his thoughtful comments [...].

Vitamin D3 Metabolism and Its Role in Temporomandibular Joint Osteoarthritis and Autoimmune Thyroid Diseases

The aim of this review was to present the metabolism of vitamin D3, as well as to discuss the role of vitamin D3 in bone metabolism, temporomandibular joint osteoarthritis (TMJ OA), and autoimmune thyroid diseases (AITD) on the basis of the literature. Vitamin D3 plays a significant role in human health, as it affects the calcium-phosphate balance and regulates the bone metabolism. Calcitriol impresses the pleiotropic effect on human biology and metabolism. Its modulative function upon the immune system is based on the reduction of Th1 cell activity and increased immunotolerance. Vitamin D3 deficiency may lead to an imbalance in the relationship between Th1/Th17 and Th2, Th17/Th reg, and is considered by some authors as one of the possible backgrounds of autoimmune thyroid diseases (AITD), e.g., Hashimoto's thyroiditis or Graves' disease. Moreover, vitamin D3, through its direct and indirect influence on bones and joints, may also play an important role in the development and progression of degenerative joint diseases, including temporomandibular joint osteoarthritis. Further randomized, double blind studies are needed to unequivocally confirm the relationship between vitamin D3 and abovementioned diseases and to answer the question concerning whether vitamin D3 supplementation may be used in the prevention and/or treatment of either AITD or OA diseases.

A Pleiotropic Nuclear Hormone Labelled Hundred Years Ago Vitamin D

This year we are celebrating 100 years of the naming of vitamin D, but the molecule is, in fact, more than one billion years old [...].