Vitamin D binding protein is required to utilize skin-generated vitamin D

The Effect of Phototherapy on Systemic Inflammation Measured with Serum Vitamin D-Binding Protein and hsCRP in Patients with Inflammatory Skin Disease

Vitamin D plays a role in inflammatory skin disease, but the exact mechanisms and the clinical significance remain unclear. According to the free hormone hypothesis, it is the free concentration of 25-hydroxy vitamin D (25(OH)D) that is biologically active. Vitamin D-binding protein (DBP) acts as the major transporter of vitamin D in the circulation, and DBP concentration defines the free 25(OH)D levels. DBP levels are elevated in various inflammatory conditions, including psoriasis. Narrowband-ultraviolet B (NB-UVB) is the most widely used phototherapy and is an established first-line treatment for psoriasis and atopic dermatitis (AD), often used before proceeding to systemic treatment. The aim of this study was to investigate the influence of NB-UVB phototherapy on DBP and high-sensitivity C-reactive protein (hsCRP) levels, as markers of systemic inflammation, in inflammatory skin disease. Thirty adults (psoriasis (n = 20) and AD (n = 10)) were treated with NB-UVB. Serum DBP, hsCRP, total and free 25(OH)D, and 1,25-dihydroxy vitamin D (1,25(OH)2D) were measured before and after NB-UVB. Disease severity was assessed with Psoriasis Area and Severity Index (PASI), SCORing Atopic Dermatitis (SCORAD), and Visual Analogue Scale (VAS). DBP decreased in psoriasis patients and varied with no clear trend in AD patients. HsCRP decreased in both groups, but this did not reach statistical significance. PASI, SCORAD, and VAS improved, and vitamin D levels increased after NB-UVB. Sub-analysis indicated a better response to NB-UVB for patients with vitamin D deficiency and insufficiency compared to vitamin D-sufficient patients. The decrease in DBP after NB-UVB in psoriasis patients suggests a potential systemic anti-inflammatory effect of phototherapy. Measurement of vitamin D levels may potentially serve as a tool to identify patients who would derive the greatest benefit from NB-UVB phototherapy.

Vitamin D regulates microbiome-dependent cancer immunity

A role for vitamin D in immune modulation and in cancer has been suggested. In this work, we report that mice with increased availability of vitamin D display greater immune-dependent resistance to transplantable cancers and augmented responses to checkpoint blockade immunotherapies. Similarly, in humans, vitamin D-induced genes correlate with improved responses to immune checkpoint inhibitor treatment as well as with immunity to cancer and increased overall survival. In mice, resistance is attributable to the activity of vitamin D on intestinal epithelial cells, which alters microbiome composition in favor of Bacteroides fragilis, which positively regulates cancer immunity. Our findings indicate a previously unappreciated connection between vitamin D, microbial commensal communities, and immune responses to cancer. Collectively, they highlight vitamin D levels as a potential determinant of cancer immunity and immunotherapy success.

Effect of UV-B irradiated vitamin D enriched yeast supplementation on milk performance and blood chemical profiles in dairy cows

OBJECTIVE

The objective was to evaluate the effects of UV-B irradiated vitamin D-enriched yeast supplementation on milk yield, milk composition, vitamin D in milk, milk fatty acids, blood chemistry, and 25(OH)D status in dairy cows.

METHODS

Six Thai Friesian cows (milk production, 11.2±2.0 kg/d; body weight, 415.0±20.0 kg; and days in milk, 90.0±6.0) were allocated to each treatment in a 3×3 Latin square design, with three treatments and three periods. Each period of the Latin square lasted 49 days consisting of 14 days for diet adaptation and 35 days for sample collection. Dairy cows were randomly assigned to one of three treatments: i) feeding a basal diet without yeast (CON); ii) basal diet + 5 g of live yeast (75 IU/head/d of vitamin D2; LY); and iii) basal diet + 5 g of UV-B irradiated vitamin D enriched yeast (150,000 IU/head/d of vitamin D2; VDY). Feed intake and milk production were recorded daily, milk sample collection occurred on days 14 and 35 of each collection period, and blood plasma was collected on days 0, 7, 14, 21, 28, and 35 of each collection period.

RESULTS

The results show that after a trial period of 14 and 35 days, the VDY group had significantly higher vitamin D content in milk than the LY and CON groups (376.41 vs 305.15, 302.14 ng/L and 413.46 vs 306.76, 301.12 ng/L, respectively). At days 7, 14, 21, 28, and 35 of the experiment, cows fed the VDY group had significantly higher 25(OH)D2 status in blood than the CON and LY groups (51.07 vs 47.16, 48.05 ng/mL; 54.96 vs 45.43, 46.91 ng/mL; 56.16 vs 46.87, 47.16 ng/mL; 60.67 vs 44.39, 46.17 ng/mL and 63.91 vs 45.88, 46.88 ng/mL), respectively.

CONCLUSION

In conclusion, UV-B irradiated vitamin D-enriched yeast supplementation could improve vitamin D content in the milk and 25(OH)D status in dairy cows during the lactation period.

Spotlight on contributory role of host immunogenetic profiling in SARS-CoV-2 infection: Susceptibility, severity, mortality, and vaccine effectiveness

BACKGROUND

The SARS-CoV-2 virus has spread continuously worldwide, characterized by various clinical symptoms. The immune system responds to SARS-CoV-2 infection by producing Abs and secreting cytokines. Recently, numerous studies have highlighted that immunogenetic factors perform a putative role in COVID-19 pathogenesis and implicate vaccination effectiveness.

AIM

This review summarizes the relevant articles and evaluates the significance of mutation and polymorphism in immune-related genes regarding susceptibility, severity, mortality, and vaccination effectiveness of COVID-19. Furthermore, the correlation between host immunogenetic and SARS-CoV-2 reinfection is discussed.

METHOD

A comprehensive search was conducted to identify relevant articles using five databases until January 2023, which resulted in 105 total articles.

KEY FINDINGS

Taken to gather this review summarized that: (a) there is a plausible correlation between immune-related genes and COVID-19 outcomes, (b) the HLAs, cytokines, chemokines, and other immune-related genes expression profiles can be a prognostic factor in COVID-19-infected patients, and (c) polymorphisms in immune-related genes have been associated with the effectiveness of vaccination.

SIGNIFICANCE

Regarding the importance of mutation and polymorphisms in immune-related genes in COVID-19 outcomes, modulating candidate genes is expected to help clinical decisions, patient outcomes management, and innovative therapeutic approach development. In addition, the manipulation of host immunogenetics is hypothesized to induce more robust cellular and humoral immune responses, effectively increase the efficacy of vaccines, and subsequently reduce the incidence rates of reinfection-associated COVID-19.

Phenome-wide Mendelian randomization study evaluating the association of circulating vitamin D with complex diseases

Background

Circulating vitamin D has been associated with multiple clinical diseases in observational studies, but the association was inconsistent due to the presence of confounders. We conducted a bidirectional Mendelian randomization (MR) study to explore the healthy atlas of vitamin D in many clinical traits and evaluate their causal association.

Methods

Based on a large-scale genome-wide association study (GWAS), the single nucleotide polymorphism (SNPs) instruments of circulating 25-hydroxyvitamin D (25OHD) from 443,734 Europeans and the corresponding effects of 10 clinical diseases and 42 clinical traits in the European population were recruited to conduct a bidirectional two-sample Mendelian randomization study. Under the network of Mendelian randomization analysis, inverse-variance weighting (IVW), weighted median, weighted mode, and Mendelian randomization (MR)–Egger regression were performed to explore the causal effects and pleiotropy. Mendelian randomization pleiotropy RESidual Sum and Outlier (MR-PRESSO) was conducted to uncover and exclude pleiotropic SNPs.

Results

The results revealed that genetically decreased vitamin D was inversely related to the estimated BMD (β = −0.029 g/cm2, p = 0.027), TC (β = −0.269 mmol/L, p = 0.006), TG (β = −0.208 mmol/L, p = 0.002), and pulse pressure (β = −0.241 mmHg, p = 0.043), while positively associated with lymphocyte count (β = 0.037%, p = 0.015). The results did not reveal any causal association of vitamin D with clinical diseases. On the contrary, genetically protected CKD was significantly associated with increased vitamin D (β = 0.056, p = 2.361 × 10−26).

Conclusion

The putative causal effects of circulating vitamin D on estimated bone mass, plasma triglyceride, and total cholesterol were uncovered, but not on clinical diseases. Vitamin D may be linked to clinical disease by affecting health-related metabolic markers.

Vitamin D attenuates biofilm-associated infections via immunomodulation and cathelicidin expression: a narrative review

INTRODUCTION

Infections are becoming more difficult to treat, at least partly on account of microbes that produce biofilms. Reports suggest that decreased levels of antimicrobial peptides like cathelicidin, elevated levels of inflammatory cytokines, and biofilm formation are all associated with vitamin D deficiency, making vitamin D - deficient individuals more susceptible to infection. Infections attributable to biofilm-producing microbes can be managed by adjuvant therapy with vitamin D because of its immunomodulatory role, particularly because of the ability of vitamin D-pathway to induce the antimicrobial peptides like cathelicidin and decrease proinflammatory cytokines.

AREAS COVERED

This narrative review covers biofilm formation, infections associated with biofilm due to vitamin D deficiency, putative role of vitamin D in host protection and the effect of vitamin D supplementation in biofilm-associated infections. A comprehensive literature search in PubMed and Google Scholar utilizing suitable keywords at multiple time points extracted relevant articles.

EXPERT OPINION

Although vitamin D deficiency has been associated with infections by biofilm producing microbes, comprehensive clinical trials in various ethnicities are required to understand the likely relationships between vitamin D receptor gene expression, cathelicidin levels, and infection outcome. Current evidence hypothesizes that maintaining normal vitamin D level can help prevent and treat these infections.

Vitamin D esters are the major form of vitamin D produced by UV irradiation in mice

The primary source of vitamin D3 for humans is that produced in skin by ultraviolet irradiation. Ultraviolet (UV) B (UVB, 280-310 nm) light causes the isomerization of 7-dehydrocholesterol (7-DHC) to pre-vitamin D3 that is thermally isomerized to vitamin D3. In addition to free vitamin D3, it has been previously reported that esterified vitamin D3 is also found in the skin of rats irradiated with UVB. We found that a large fraction of the vitamin D3 precursor, 7-dehydrocholesterol is in the esterified form. Following UVB irradiation, vitamin D3 esters represent the majority of tissue vitamin D3, comprising approximately 80% in mice. Examination of vitamin D3 ester transport from skin in DBP^-/- mice demonstrated that skin vitamin D3 ester content decreased only in the presence of DBP. No significant binding of vitamin D3 esters by serum was observed and no vitamin D3 esters were detectable in mouse serum after UVB treatment, indicating that the esters are hydrolyzed prior to transport into the circulation. The significance of vitamin D3 esters and their hydrolysis is the subject of current investigation.

Vitamin D in dairy cows: metabolism, status and functions in the immune system

The function of vitamin D in calcium homoeostasis in dairy cows, such as in other vertebrates, is known for many years. In recent years, new and interesting, non-classical functions of vitamin D have been elucidated, including effects on the immune system. The major aim of this review is to provide an overview of effects of vitamin D or its metabolites on the immune system in dairy cows. The first part of the review provides an overview of vitamin D metabolism, with particular reference to the role of various proteins (25- and 1-hydroxylases, vitamin D binding protein, vitamin D receptor) in vitamin D signalling. The second part deals with the role of the concentration of 25-hydroxyvitamin D [25(OH)D] in plasma as an indicator of the vitamin D status in dairy cows, and its dependence on sunlight exposure and dietary vitamin D supplementation. In this part also the "free hormone hypothesis" is discussed, indicating that the concentration of free 25(OH)D might be a more valid indicator of the vitamin D status than the concentration of total 25(OH)D. The third part deals with classical and the non-classical functions of vitamin D. Among the non-classical functions which are based on an autocrine vitamin D signalling, particular reference is given to the effects of vitamin D and vitamin D metabolites on the immune system in bovine immune cells and in dairy cows. Recent findings provide some indication that vitamin D or its metabolite 25(OH)D could enhance the immune function in dairy cows and be useful for the prevention and therapy of mastitis. However, the number of studies reported so far in this respect is very limited. Thus, much more research is required to yield clear concepts for an optimised usage of vitamin D to improve the immune system and prevent infectious diseases in dairy cows.

Physiological significance of vitamin D produced in skin compared with oral vitamin D

Since the discovery of vitamin D, it has been accepted that its physiological supply is either from food or by endogenous synthesis in skin exposed to solar UV light. Yet vitamin D is a component of very few foods and its supply as a natural nutrient is unable to maintain good vitamin D status for human populations. One aspect of vitamin D physiology that has been ignored is that the mechanisms for its transport and processing from these two sources are quite different. Excess intake of vitamin D causes hypercalcaemic toxicity. However, experiments with different animal species have shown that long-term supply of oral vitamin D in apparently non-toxic amounts causes atherosclerosis in large arteries. A mechanism for this toxicity is proposed. Alternative strategies for addressing widespread vitamin D deficiency by food fortification should be considered in light of the angiotoxicity caused by oral vitamin D in animal experiments.

Ovariectomy Interferes with Proteomes of Brown Adipose Tissue in Rats

Postmenopausal women exhibit a higher prevalence of obesity due to decreased energy expenditure and increased food intake compared to their premenopausal counterparts. Brown adipose tissue (BAT) plays a key role in energy homeostasis, thus providing us with appealing therapeutic targets in obesity. However, how BAT proteomes are altered in response to low levels of estrogen remains unclear. To better understand the underlying mechanisms between the postmenopausal state and BAT proteomic changes, our study aimed to investigate the effect of ovariectomy on the BAT proteome. In this study, eight-week-old female Sprague Dawley rats were randomly allocated into bilateral ovariectomy (Ovx) and sham operation (Sham) groups. Mass spectrometry was used for proteomics assay and Ingenuity Pathway Analysis was applied to examine the differentially regulated proteins. Of the 1,412 identified proteins, 18 proteins were significantly upregulated, whereas 36 proteins were significantly downregulated in the Ovx group as compared to the Sham group. Our findings demonstrate that the proteins involved in BAT morphology, the browning of white adipose tissue, and metabolic substrates for thermogenesis were regulated by ovariectomy. The dysregulation of proteins by ovariectomy might be related to the disruption of BAT function in the postmenopausal status. Understanding how BAT proteomes are altered in response to ovariectomy may illuminate novel therapeutic strategies for the management of postmenopausal weight gain in the future.

Vitamin D binding protein greatly improves bioactivity but is not essential for orally administered vitamin D

Vitamin D3 is a prohormone that is essential for calcium homeostasis. It is naturally produced in the skin by ultraviolet-B (UVB) irradiation of 7-dehydrocholesterol. In the absence of skin production, vitamin D3 can also be obtained from oral sources. However, the actual biological equivalence of naturally produced (i.e., UVB-irradiation of skin) and oral vitamin D3  has not been determined. We previously identified a unique and specific transport mechanism for skin-generated vitamin D3 which requires vitamin D binding protein (DBP); a mechanism that differs from absorption and transport of oral vitamin D3 . In the following report, we examined the impact of this difference on the biological activity of vitamin D3 . We report that UVB-generated vitamin D3 is more potent at raising serum calcium compared to oral vitamin D3 , with the total biological activity being twofold higher. By examining the excretion of radiolabeled vitamin D3 injected unbound or pre-bound by DBP, we attributed the increased activity of skin-generated vitamin D3 to a significant reduction in biliary excretion of DBP-bound vitamin D relative to unbound vitamin D. Thus, removal of vitamin D3 from the skin by the natural DBP system markedly improves biological activity compared to that given orally.

Vitamin D toxicity related to its physiological and unphysiological supply

Vitamin D is defined as a nutrient despite its rare occurrence in food. Vitamin D status is determined mainly by solar UV light action in skin. However, the strategy to combat vitamin D deficiency has been to increase oral intake of vitamin D in greater amounts than could be obtained from food. Persistent large intakes of vitamin D can cause hypercalcaemic toxicity. Although the amounts recommended to prevent deficiency are far less than those causing such toxicity, the possibility of other toxic actions from increased intake of vitamin D has been ignored. Animal experiments have demonstrated that moderate amounts of oral vitamin D over time result in atherosclerosis. Differences in the fate of vitamin D could explain this angiotoxicity.

Immunomodulation of T Helper Cells by Tumor Microenvironment in Oral Cancer Is Associated With CCR8 Expression and Rapid Membrane Vitamin D Signaling Pathway

The immune system plays a key role in the protective response against oral cancer; however, the tumor microenvironment (TME) impairs this anti-cancer response by modulating T helper (Th) responses and promoting an anti-inflammatory environment. Regulatory T cells (Tregs) and Th2 effector cells (Teff) are associated with poor prognosis in oral squamous cell carcinoma (OSCC). However, the main immunomodulatory mechanisms associated with the enrichment of these subsets in OSCC remain unknown. We characterized Th-like lineages in Tregs and Teff and evaluated immunomodulatory changes induced by the TME in OSCC. Our phenotypic data revealed a higher distribution of tumour-infiltrating CCR8⁺ and Th2-like Treg in OSCC compared with non-malignant samples, whereas the percentages of Th1 cells were reduced in cancer. We then analyzed the direct effect of the TME by exposing T cell subsets to cancer secretomes and observed the OSCC secretome induced CCR8 expression and reduced cytokine production from both subsets. Transcriptomic analysis showed that the co-culture with OSCC secretome induced several gene changes associated with the vitamin D (VitD) signaling pathway in T cells. In addition, proteomic analysis identified the presence of several proteins associated with prostaglandin E2 (PGE2) production by rapid membrane VitD signaling and a reduced presence of the VitD binding protein. Thus, we analyzed the effect of VitD and PGE2 and observed that VitD promotes a regulatory Th2-like response with CCR8 expression whilst PGE2 also modulated CCR8 but inhibited cytokine production in combination with VitD. Finally, we evaluated the presence of CCR8 ligand in OSCC and observed increased chemokine CCL18, which was also able to upregulate CCR8 in activated Th cells. Overall, our data showed the immunomodulatory changes induced by the TME involving CCR8 expression and regulatory Th2 phenotypes, which are associated with PGE2 mediated VitD signaling pathway and CCL18 expression in OSCC.

MicroRNA‑378d inhibits Glut4 by targeting Rsbn1 in vitamin D deficient ovarian granulosa cells

Vitamin D (VD) is not only associated with bone growth and development, but is also closely associated with numerous other pathological conditions. The present study aimed to investigate the effect of microRNA (miRNA/miR)-378d on ovarian granulosa cells by regulating the round spermatid basic protein 1 (Rsbn1) in the absence of VD. The abnormal expression of miRNAs in ovarian tissues of the VD-deficient mouse was analyzed using transcriptome sequencing. miR-378d, glucose transporter 4 (Glut4) and aromatase (Cyp19a) expression levels were examined via reverse transcription-quantitative (RT-q)PCR and western blotting. The expression levels of Rsbn1, Glut4 and Cyp19a were detected in transfected mouse ovarian granulosa cells. The targeting regulation between miR-378d and Rsbn1 was verified using double reporter gene assay and functional rescue experiments. Among the 672 miRNAs that were differentially expressed, cluster analysis revealed that 17 were significantly upregulated and 16 were significantly downregulated. Moreover, miR-378d showed significant upregulation, which was further verified via RT-qPCR. It was identified that the protein expression level of Rsbn1 was significantly downregulated. Furthermore, Glut4 mRNA expression was significantly decreased in the mimic group but markedly increased in the inhibitor group. By contrast, the mRNA expression levels of Rsbn1 and Cyp19a did not demonstrate any significant difference. The western blotting results indicated that the protein expression levels of Rsbn1 and Glut4 were decreased and increased, respectively, while Cyp19a did not show any significant change. In addition, the double reporter gene experiments confirmed that Rsbn1 was the target gene of miR-378d. Collectively, the present results demonstrated that miR-378d was abnormally overexpressed in the ovarian tissues of the VD-deficient mice, and that miR-378d could inhibit Glut4 production by targeting Rsbn1, which may lead to insulin resistance.

Maternal vitamin D deficiency influences long-chain polyunsaturated fatty acids and pregnancy outcome in association with alterations in one-carbon metabolism

Preeclampsia is a pregnancy-specific disorder, leading to maternal and infant morbidity and mortality. Abnormal placentation has been reported in preeclampsia. Nutrients like vitamin D and long-chain polyunsaturated fatty acids (LCPUFA) are known to play a role in placental development. In an animal model, we have previously demonstrated that maternal vitamin D deficiency increases the thromboxane/prostacyclin ratio and contributes to inflammation and vasoconstriction. We hypothesize that maternal vitamin D status influences placental LCPUFA metabolism through alterations in one carbon metabolism in women with preeclampsia. To test this hypothesis, we recruited 69 normotensive control (NC) women and 50 women with preeclampsia. Women with preeclampsia had lower placental protein and mRNA levels of cystathionine-β-synthase (CBS), higher plasma malondialdehyde (MDA) levels and higher levels of arachidonic acid (AA) and total omega-6 fatty acids in the placenta. Women with preeclampsia also demonstrated higher placental mRNA levels of cyclooxygenase-2 (COX-2) as compared to NC women. Maternal 25(OH)D levels were negatively associated with maternal plasma MDA levels. Placental vitamin D receptor (VDR) levels were positively associated with CBS while maternal MDA levels were positively associated with serum levels of thromboxane-B2 (TXB2) levels. Our findings indicate that vitamin D deficiency increases oxidative stress through alterations in one carbon metabolism to influence pro-inflammatory omega-6 metabolic pathway in the placenta. This study demonstrates a possible mechanism through which vitamin D deficiency can result in an imbalance in the LCPUFA metabolites and contribute to placental inflammation and endothelial dysfunction in preeclampsia.

Ionizing Radiation as a Source of Oxidative Stress-The Protective Role of Melatonin and Vitamin D

Ionizing radiation (IR) has found widespread application in modern medicine, including medical imaging and radiotherapy. As a result, both patients and healthcare professionals are exposed to various IR doses. To minimize the negative side effects of radiation associated with oxidative imbalance, antioxidant therapy has been considered. In this review, studies on the effects of melatonin and vitamin D on radiation-induced oxidative stress are discussed. According to the research data, both substances meet the conditions for use as agents that protect humans against IR-induced tissue damage. Numerous studies have confirmed that melatonin, a hydro- and lipophilic hormone with strong antioxidant properties, can potentially be used as a radioprotectant in humans. Less is known about the radioprotective effects of vitamin D, but the results to date have been promising. Deficiencies in melatonin and vitamin D are common in modern societies and may contribute to the severity of adverse side effects of medical IR exposure. Hence, supporting supplementation with both substances seems to be of first importance. Interestingly, both melatonin and vitamin D have been found to selectively radiosensitise cancer cells, which makes them promising adjuvants in radiotherapy. More research is needed in this area, especially in humans.

Exploration of Oxygen-Induced Retinopathy Model to Discover New Therapeutic Drug Targets in Retinopathies

Oxygen-induced retinopathy (OIR) is a pure hypoxia-driven angiogenesis model and the most widely used model for ischemic retinopathies, such as retinopathy of prematurity (ROP), proliferative diabetic retinopathy (PDR), and retinal vein occlusion (RVO). OIR model has been used to test new potential anti-angiogenic factors for human diseases. We have recently performed the most comprehensive characterization of OIR by a relatively novel mass spectrometry (MS) technique, sequential window acquisition of all theoretical fragment ion mass spectra (SWATH-MS) proteomics and used genetically modified mice strains to identify novel molecular drug targets in angiogenic retinal diseases. We have confirmed the relevance of the identified molecular targets to human diseases by determining their expression pattern in neovascular membranes obtained from PDR and RVO patients. Based on our results, crystallins were the most prominent proteins induced by early hypoxic environment during the OIR, while actomyosin complex and Filamin A-R-Ras axis, that regulates vascular permeability of the angiogenic blood vessels, stood out at the peak of angiogenesis. Our results have revealed potential new therapeutic targets to address hypoxia-induced pathological angiogenesis and the associated vascular permeability in number of retinal diseases.