Extrarenal expression of 25-hydroxyvitamin d(3)-1 alpha-hydroxylase

One-carbon metabolism nutrients impact the interplay between DNA methylation and gene expression in liver, enhancing protein synthesis in Atlantic salmon

Supplementation of one-carbon (1C) metabolism micronutrients, which include B-vitamins and methionine, is essential for the healthy growth and development of Atlantic salmon (Salmo salar). However, the recent shift towards non-fish meal diets in salmon aquaculture has led to the need for reassessments of recommended micronutrient levels. Despite the importance of 1C metabolism in growth performance and various cellular regulations, the molecular mechanisms affected by these dietary alterations are less understood. To investigate the molecular effect of 1C nutrients, we analysed gene expression and DNA methylation using two types of omics data: RNA sequencing (RNA-seq) and reduced-representation bisulphite sequencing (RRBS). We collected liver samples at the end of a feeding trial that lasted 220 days through the smoltification stage, where fish were fed three different levels of four key 1C nutrients: methionine, vitamin B6, B9, and B12. Our results indicate that the dosage of 1C nutrients significantly impacts genetic and epigenetic regulations in the liver of Atlantic salmon, particularly in biological pathways related to protein synthesis. The interplay between DNA methylation and gene expression in these pathways may play an important role in the mechanisms underlying growth performance affected by 1C metabolism.

Therapeutic potential of vitamin D3 in mitigating high glucose‑induced renal damage: Mechanistic insights into oxidative stress inhibition and TXNIP/NLRP3 signaling pathway blockade

In the development of diabetic nephropathy, pathological damage such as interstitial fibrosis and cell apoptosis often occur in renal tubules. In the present study, diabetic and control group mice were randomly treated with vitamin D3 or vehicle for 6 months. In addition, human renal tubular epithelial (HK-2) cells were cultured in high-glucose medium and treated with vitamin D3 or the oxidative inhibitor NAC. Immunohistochemistry, western blotting, quantitative PCR), and ELISA showed that vitamin D3 decreased the expression of α-smooth muscle actin and E-cadherin in renal tubular epithelial cells, improving interstitial fibrosis. It also downregulated the ratio of Bax/Bcl2 protein, alleviating apoptosis in renal tubular epithelial cells. Furthermore, vitamin D3 significantly inhibited oxidative stress response in renal tubular epithelial cells and blocked the (Thioredoxin Interacting Protein) TXNIP/NLRP3 inflammatory pathway. Therefore, vitamin D3 can protect renal tubular epithelial cells from fibrosis and apoptosis by inhibiting oxidative stress response and blocking the TXNIP/NLRP3 inflammatory pathway in diabetic nephropathy.

Associations Between Vitamin K and Suicide Attempts in Patients with Depression: A Case-Control Study

Background

Hypovitaminosis K has been linked to depression and suicide, but epidemiological research is scarce. This study aimed to explore the association among vitamin K with depression and suicidal attempts.

Methods

This was a retrospective cross-sectional study involving 146 cases with a history of suicidal attempts and 149 subjects without a lifetime history of suicidal attempts. The levels of thyroid hormones, lipid profile, inflammatory cytokines, and vitamins were measured.

Results

Subjects who had suicidal attempts presented with a significant decrease in FT4, TC, vitamin D, and vitamin K but increased CRP levels. In these variables, vitamin K has a better diagnostic value for suicidal attempts in depressed patients, with a sensitivity of 0.842 and a specificity of 0.715. Correlation analysis suggested that vitamin K was significantly and positively related to FT4, TC, LDL, and sdLDL. Multivariate analysis showed that serum vitamin K level predicts suicidal attempts in depressive patients (OR = 0.614, P = 0.004, 95% CI 0.153-0.904). Moreover, a negative correlation between vitamin K and suicidal attempts was also noted for partial FT4, CRP, and vitamin D strata analysis.

Conclusion

Our study suggests that low vitamin K levels were correlated with suicidal attempts in patients with depression, indicating that vitamin K deficiency might be a biological risk factor for depression.

C-reactive protein as a novel biomarker for vitamin D deficiency in alopecia areata

BACKGROUND

Alopecia areata (AA) is an autoimmune condition characterized by sudden and unpredictable hair loss, with a lifetime incidence of 2%. AA can be divided into three categories: patchy alopecia, alopecia totalis, and alopecia universalis. It can affect a person's psychological health and overall quality of life. Elevated C-reactive protein (CRP) levels in the liver may indicate an inflammatory response in autoimmune diseases. Vitamin D, essential for immune system control and skin health, may be related to AA. Hair follicles contain vitamin D receptors, which control immunological responses in the skin. However, no study has found a relationship between CRP and vitamin D in AA patients in our region.

SUBJECTS AND METHODS

An analytical cross-sectional study with a case-control design research investigation of 82 AA patients and 81 healthy controls was carried out. Both groups' medical histories were taken. Biochemical analysis was done for both groups as well as the serum vitamin D levels, and CRP. Genetic analysis for CDX2 rs11568820 variant detected by PCR (T-ARMS-PCR) method and vitamin D receptor (VDR) gene expression measured by real-time PCR analysis for both patients and healthy subjects.

RESULTS

CRP levels are higher in AA patients, AA patients with G/G genotypes exhibited higher concentrations of CRP when compared to those with A/A and A/G genotypes while patients with A/A genotypes have higher levels of Serum vitamin D as compared to the A/G and G/G genotypes. G allele was more abundant in AA patients. VDR gene expression was lower in AA compared to control and lower in ophiasis compared to localized and multiple patchy AA. An important inverse linear correlation was observed between vitamin D and CRP levels in ophiasis AA.

CONCLUSION

CRP concentrations were found to be elevated in AA patients. The considerable accuracy of CRP in the diagnosis of AA is substantiated by a statistically significant al. A noteworthy inverse linear association was observed between serum vitamin D and CRP concentrations in ophiasis AA.

Expression of vitamin D receptor, CYP24A1, and CYP27B1 in normal and inflamed canine pancreases

Vitamin D plays a role in anti-inflammatory processes, and the alteration of its metabolism is associated with the inflammatory processes of pancreatitis. This study was performed to evaluate the expression of the vitamin D receptor (VDR) and the two major enzymes that regulate vitamin D metabolism, 1α-hydroxylase (CYP27B1) and 24-hydroxylase (CYP24A1), in the canine pancreas and to compare their degrees of immunoreactivity between normal and inflamed pancreases. Five normal and inflamed pancreatic tissues each were obtained from six dogs. The expression of VDR, CYP24A1, and CYP27B1 were determined immunohistochemically, and the degree of immunostaining was assessed semiquantitatively. The VDR was expressed in the ducts, acini, and islets of Langerhans of normal pancreases and in the ducts and acini of inflamed ones. There was a significant difference in the immunoreactivity score for VDR in the islets of Langerhans between normal (median, 3 [interquartile range, 2-7.5] score) and inflamed pancreatic tissues (0 [0-0.5] score, p = 0.03). CYP24A1 was expressed in the ducts and islets of Langerhans in both normal and inflamed pancreases, whereas CYP27B1 was expressed in the ducts and acini in only some normal and inflamed pancreatic tissues. This study showed that VDR expression decreased in inflamed pancreases and demonstrated CYP24A1 and CYP27B1 expression in the canine pancreas for the first time. These findings indicate that the pancreas could regulate the metabolism and biological activity of vitamin D and suggest that a decrease in these might be related to the pathophysiology of pancreatitis.

Familial parathyroid tumours-comparison of clinical profiles between syndromes

INTRODUCTION

Primary hyperparathyroidism (PHPT) caused by parathyroid tumours is mostly sporadic, with a genetic cause identified in 5-10% of cases. Familial parathyroid tumours can be included in complex syndromes, such as multiple endocrine neoplasia (MEN) type 1, 2A and 4 or hyperparathyroidism-jaw tumour syndrome (HPT-JT).

OBJECTIVE

Characterisation of the familial parathyroid tumours followed-up at our centre and comparison of the different clinicopathological manifestations between the syndromes.

METHODS

Retrospective analysis of 48 patients with familial parathyroid tumours harbouring RET (n = 11), CDC73 (n = 20) and MEN1 (n = 17) germline mutations was performed.

RESULTS

Cases of PHPT in MEN2A syndrome presented with lower serum PTH (sPTH) and serum calcium (sCa) levels at diagnosis (sPTH = 108.0 (IQR 53.3) pg/mL, sCa = 10.6 ± 1.1 mg/dL) than MEN1 (sPTH = 196.9 (IQR 210.5) pg/mL, sCa = 11.7 ± 1.2 mg/dL) (p = 0.01, p = 0.03, respectively) or HPT-JT cases (sPTH = 383.5 (IQR 775.8) pg/mL, sCa = 12.9 ± 1.8 mg/dL) (p = 0.01; p < 0.001, respectively). There was a statistical difference in sCa levels between MEN1 and HPT-JT (p = 0.02), but not between sPTH (p = 0.07). The predominant first manifestation of the syndrome in MEN1 was gastroenteropancreatic neuroendocrine tumour (GEP-NET) in 47.1% of the cases, in MEN2A was medullary thyroid cancer (90.9%) and in HPT-JT was PHPT in 85% patients. In MEN1 syndrome, the number of affected parathyroid glands was significantly higher than in MEN2A (p < 0.001) and HPT-JT (p = 0.01).

CONCLUSION

The first manifestation of the syndrome in MEN1 cases was GEP-NET and not PHPT. Although presenting at similar ages, patients with MEN2A exhibit less severe biochemical and clinical PHPT at diagnosis than the other familial syndromes.

Vitamin D in Cancer Prevention: Gaps in Current Knowledge and Room for Hope

Intensive epigenome and transcriptome analyses have unveiled numerous biological mechanisms, including the regulation of cell differentiation, proliferation, and induced apoptosis in neoplastic cells, as well as the modulation of the antineoplastic action of the immune system, which plausibly explains the observed population-based relationship between low vitamin D status and increased cancer risk. However, large randomized clinical trials involving cholecalciferol supplementation have so far failed to show the potential of such interventions in cancer prevention. In this article, we attempt to reconcile the supposed contradiction of these findings by undertaking a thorough review of the literature, including an assessment of the limitations in the design, conduct, and analysis of the studies conducted thus far. We examine the long-standing dilemma of whether the beneficial effects of vitamin D levels increase significantly above a critical threshold or if the conjecture is valid that an increase in available cholecalciferol translates directly into an increase in calcitriol activity. In addition, we try to shed light on the high interindividual epigenetic and transcriptomic variability in response to cholecalciferol supplementation. Moreover, we critically review the standards of interpretation of the available study results and propose criteria that could allow us to reach sound conclusions in this field. Finally, we advocate for options tailored to individual vitamin D needs, combined with a comprehensive intervention that favors prevention through a healthy environment and responsible health behaviors.

Is Season of Diagnosis a Predictor of Cancer Survival? Results from the Zurich Cancer Registry

In Switzerland, there is a large seasonal variation in sunlight, and vitamin D deficiency is relatively common during winter. The season of diagnosis may be linked to cancer survival via vitamin D status. Using data from the Cancer Registry of Zurich, Zug, Schaffhausen, and Schwyz with more than 171,000 cancer cases registered since 1980, we examined the association of the season of diagnosis with survival for cancers including prostate (ICD10 code C61; International Categorization of Diseases, version 10), breast (C50), colorectal (C18-21), lung (C34), melanoma (C43), and all sites combined. Cox proportional hazards regression models were used to assess the differences in the all-cause mortality by the season of the diagnosis. Winter was used as the reference season. Hazard ratios (HR) and 95% confidence intervals (CI) were calculated for all the cancers combined (excluding nonmelanoma skin cancer) and for prostate (in men), breast (in women), colorectal, lung cancer, and melanomas, separately. A diagnosis in summer and/or autumn was associated with improved survival in all the sites combined for both sexes (men: HR 0.97 [95% CI 0.96-0.99]; women: HR 0.97 [95% CI 0.94-0.99]) and in colorectal (HR 0.91 [95% CI 0.84-0.99]), melanoma (HR 0.81 [95% CI 0.65-1.00]), and breast cancer (HR 0.91 [95% CI 0.94-0.99]) in women. Our study results suggest that a cancer diagnosis in summer and/or autumn is associated with a better prognosis. The improved seasonal survival coincides with the seasonal variation of sun-induced vitamin D, and vitamin D may play a protective and beneficial role in cancer survival.

Vitamin D Exerts Significant Antitumor Effects by Suppressing Vasculogenic Mimicry in Breast Cancer Cells

Background

Numerous clinical and experimental observations have alluded to the substantial anti-neoplastic role of vitamin D in breast cancer (BC), primarily by inducing apoptosis and affecting metastasis. Tumor progression and resistance to chemotherapy have been linked to vasculogenic mimicry (VM), which represents the endothelial-independent formation of microvascular channels by cancer cells. However, the effect of vitamin D on VM formation in BC has not been thoroughly investigated. This study examined the impact of 1α,25-dihydroxyvitamin D3 (calcitriol), the active form of vitamin D, on the expression of major factors involved in BC migration, invasion, and VM formation.

Experimental Methods

Publicly available transcriptomic datasets were used to profile the expression status of the key VM markers in vitamin D-treated BC cells. The in silico data were validated by examining the expression and activity of the key factors that are involved in tumor progression and MV formation in hormone-positive MCF-7 and aggressive triple‐negative MDA-MB-231 BC cells after treatment with calcitriol.

Results and Discussions

The bioinformatics analysis showed that tumor VM formation-enriched pathways were differentially downregulated in vitamin D-treated cells when compared with control counterparts. Treatment of BC cells with calcitriol resulted in increased expression of tissue inhibitors of metalloproteinases (TIMPs 1 and 2) and decreased content and gelatinolytic activity of matrix metalloproteinases (MMPs 2 and 9). Furthermore, calcitriol treatment reduced the expression of several pro-MV formation regulators including vascular endothelial growth factor (VEGF), tumor growth factor (TGF-β1), and amphiregulin. Eventually, this process resulted in a profound reduction in cell migration and invasion following the treatment of BC cells with calcitriol when compared to the controls. Finally, the formation of VM was diminished in the aggressive triple‐negative MDA-MB-231 cancer cell line after calcitriol treatment.

Conclusion

Our findings demonstrate that vitamin D mediates its antitumor effects in BC cells by inhibiting and curtailing their potential for VM formation.

Vitamin D, infections and immunity

Vitamin D, best known for its role in skeletal health, has emerged as a key regulator of innate immune responses to microbial threat. In immune cells such as macrophages, expression of CYP27B1, the 25-hydroxyvitamin D 1α-hydroxylase, is induced by immune-specific inputs, leading to local production of hormonal 1,25-dihydroxyvitamin D (1,25D) at sites of infection, which in turn directly induces the expression of genes encoding antimicrobial peptides. Vitamin D signaling is active upstream and downstream of pattern recognition receptors, which promote front-line innate immune responses. Moreover, 1,25D stimulates autophagy, which has emerged as a mechanism critical for control of intracellular pathogens such as M. tuberculosis. Strong laboratory and epidemiological evidence links vitamin D deficiency to increased rates of conditions such as dental caries, as well as inflammatory bowel diseases arising from dysregulation of innate immune handling intestinal flora. 1,25D is also active in signaling cascades that promote antiviral innate immunity; 1,25D-induced expression of the antimicrobial peptide CAMP/LL37, originally characterized for its antibacterial properties, is a key component of antiviral responses. Poor vitamin D status is associated with greater susceptibility to viral infections, including those of the respiratory tract. Although the severity of the COVID-19 pandemic has been alleviated in some areas by the arrival of vaccines, it remains important to identify therapeutic interventions that reduce disease severity and mortality, and accelerate recovery. This review outlines of our current knowledge of the mechanisms of action of vitamin D signaling in the innate immune system. It also provides an assessment of the therapeutic potential of vitamin D supplementation in infectious diseases, including an up-to-date analysis of the putative benefits of vitamin D supplementation in the ongoing COVID-19 crisis.

Maternal Vitamin D Status Correlates to Leukocyte Antigenic Responses in Breastfeeding Infants

It is unknown if vitamin D (vitD) sufficiency in breastfeeding mothers can lead to physiological outcomes for their children that are discernible from infant vitD sufficiency per se. In a 3-month, randomized vitD supplementation study of mothers and their exclusively breastfeeding infants, the effects of maternal vitD sufficiency were determined on infant plasma concentrations of 25-hydroxyvitamin D (i.e., vitD status) and 11 cytokines. An inverse correlation was seen between maternal vitD status and infant plasma TNF concentration (r = −0.27; p < 0.05). Infant whole blood was also subjected to in vitro antigenic stimulation. TNF, IFNγ, IL-4, IL-13, and TGFβ1 responses by infant leukocytes were significantly higher if mothers were vitD sufficient but were not as closely correlated to infants’ own vitD status. Conversely, IL-10 and IL-12 responses after antigenic challenge were more correlated to infant vitD status. These data are consistent with vitD-mediated changes in breast milk composition providing immunological signaling to breastfeeding infants and indicate differential physiological effects of direct-infant versus maternal vitD supplementation. Thus, consistent with many previous studies that focused on the importance of vitD sufficiency during pregnancy, maintenance of maternal sufficiency likely continues to affect the health of breastfed infants.

Emerging Roles of Vitamin D-Induced Antimicrobial Peptides in Antiviral Innate Immunity

Vitamin D deficiency, characterized by low circulating levels of calcifediol (25-hydroxyvitamin D, 25D) has been linked to increased risk of infections of bacterial and viral origin. Innate immune cells produce hormonal calcitriol (1,25-dihydroxyvitamin D, 1,25D) locally from circulating calcifediol in response to pathogen threat and an immune-specific cytokine network. Calcitriol regulates gene expression through its binding to the vitamin D receptor (VDR), a ligand-regulated transcription factor. The hormone-bound VDR induces the transcription of genes integral to innate immunity including pattern recognition receptors, cytokines, and most importantly antimicrobial peptides (AMPs). Transcription of the human AMP genes β-defensin 2/defensin-β4 (HBD2/DEFB4) and cathelicidin antimicrobial peptide (CAMP) is stimulated by the VDR bound to promoter-proximal vitamin D response elements. HDB2/DEFB4 and the active form of CAMP, the peptide LL-37, which form amphipathic secondary structures, were initially characterized for their antibacterial actively. Notably, calcitriol signaling induces secretion of antibacterial activity in vitro and in vivo, and low circulating levels of calcifediol are associated with diverse indications characterized by impaired antibacterial immunity such as dental caries and urinary tract infections. However, recent work has also provided evidence that the same AMPs are components of 1,25D-induced antiviral responses, including those against the etiological agent of the COVID-19 pandemic, the SARS-CoV2 coronavirus. This review surveys the evidence for 1,25D-induced antimicrobial activity in vitro and in vivo in humans and presents our current understanding of the potential mechanisms by which CAMP and HBD2/DEFB4 contribute to antiviral immunity.

A randomized pilot study using calcitriol in hospitalized COVID-19 patients

The systemic illness associated with SARS-CoV-2 infection results in hospitalization rate of 380.3 hospitalizations per 100,000 population, overwhelming health care systems. Vitamin D regulates expression of approximately 11,000 genes spanning many physiologic functions that include regulation of both innate and adaptive immune function. We investigate potential benefit of calcitriol therapy given to patients hospitalized with COVID-19. This was an open label, randomized clinical trial of calcitriol or no treatment given to hospitalized adult patients with COVID-19. Subjects were randomly assigned treatment with calcitriol 0.5 μg daily for 14 days or hospital discharge; or no treatment (1:1) at time of enrollment. We enrolled 50 consecutive patients, 25 per trial arm. The change in peripheral arterial oxygen saturation to the inspired fraction of oxygen (SaO2/FIO2 ratio) was calculated on admission and discharge between the groups. The control group had an average increase of +13.2 (±127.7) on discharge and the calcitriol group had an increase of +91.04 (±119.08) (p = .0305), suggesting an improvement in oxygenation among subjects who received calcitriol. Additionally, 12 patients in the control group required oxygen supplementation on admission and 21 of them were discharged on room air. 14 subjects needed oxygen supplementation in the calcitriol group on admission while all 25 were discharged on room air. Other clinical markers showed the average length of stay was 9.24 (±9.4) in the control group compared to 5.5 (±3.9) days in the calcitriol group (p = .14). The need for ICU transfer was 8 in the control group and 5 in the calcitriol group. There were 3 deaths and 4 readmissions in the control group and 0 deaths and 2 readmissions in the calcitriol group. This pilot study illustrates improvement in oxygenation among hospitalized patients with COVID-19 treated with calcitriol and suggests the need for a larger randomized trial.

High-dose Vitamin D Supplementation and Improvement in Cognitive Abilities, Insomnia, and Daytime Sleepiness in Adolescent Girls

Introduction:

Vitamin D may affect the modulation of signaling pathways in the central nervous system. We aimed to evaluate the effect of high-dose vitamin D supplementation on neuropsychological functions in female adolescents.

Methods:

We studied the effects of 9 weeks of vitamin D supplementation (50000 IU vitamin D3 [cholecalciferol]/week) on cognitive abilities and sleep disorders in 940 adolescent girls.

Results:

Oral vitamin D supplementation improved cognitive abilities, including memory, inhibitory control, selective attention, decision making, planning, sustained attention, and cognitive flexibility in healthy adolescent girls (P<0.001). The prevalence of subjects with insomnia after intervention fell from 15.0% to 11.3%. Similar results were also found for the prevalence of sleepiness (15.6% reduced to 14.7%), or cases with both insomnia and sleepiness (8.0% reduced to 6.1%; P<0.05).

Conclusion:

High dose of vitamin D can improve cognitive abilities and alleviate insomnia and daytime sleepiness in adolescent girls. Further investigations are required on different population groups (age and gender) to determine the sustainability of these effects. The value of vitamin D therapy in other neurological disorders would also be of research interest.

Synergistic stimulation of osteoblast differentiation of rat mesenchymal stem cells by leptin and 25(OH)D3 is mediated by inhibition of chaperone-mediated autophagy

Background

Vitamin D is important for the mineralization of bones by stimulating osteoblast differentiation of bone marrow mesenchymal stem cells (BMMSCs). BMMSCs are a target of vitamin D action, and the metabolism of 25(OH)D₃ to biologically active 1α,25(OH)₂D₃ in BMMSCs promotes osteoblastogenesis in an autocrine/paracrine manner. Our previous study with human BMMSCs showed that megalin is required for the 25(OH)D₃-DBP complex to enter cells and for 25(OH)D₃ to stimulate osteoblast differentiation in BMMSCs. Furthermore, we reported that leptin up-regulates megalin in those cells. Leptin is a known inhibitor of PI3K/AKT-dependent chaperone-mediated autophagy (CMA). In this study, we tested the hypothesis that leptin acts synergistically with 25(OH)D₃ to promote osteoblastogenesis in rat BMMSCs by a mechanism that entails inhibition of PI3K/AKT-dependent CMA.

Methods

BMMSCs were isolated from rat bone marrow (4-week-old male SD rats); qRT-PCR and western immunoblots or immunofluorescence were used to evaluate the expression of megalin, ALP, COL1A1, RUNX2, OSX, OSP, and CMA in rBMMSCs. The osteoblast differentiation was evaluated by ALP activity, ALP staining, and calcium deposition. The viability of rBMMSCs was assessed with the CCK-8 kit. Biosynthesis of 1α,25(OH)₂D₃ was measured by a Rat 1α,25(OH)₂D₃ ELISA Kit.

Results

The combination of leptin and 25(OH)D₃ treatment significantly enhanced osteoblast differentiation as shown by ALP activity, ALP staining, and calcium deposition, the expression of osteogenic genes ALP, COL1A1, RUNX2, OSX, and OSP by qRT-PCR and western immunoblots in rBMMSCs. Leptin enhanced the expression of megalin and synthesis of 1α,25(OH)₂D₃ in rBMMSCs. Our data showed that leptin inhibited CMA activity of rBMMSCs by activating PI3K/AKT signal pathway; the ability of leptin to enhance 25(OH)D₃ promoted osteoblast differentiation of rBMMSCs was weakened by the PI3K/AKT signal pathway inhibitor.

Conclusions

Our data reveal the mechanism by which leptin and 25(OH)D₃ promote osteoblast differentiation in rBMMSCs. Leptin promoted the expression of megalin by inhibiting CMA, increased the utilization of 25(OH)D₃ by rBMMSCs, and enhanced the ability of 25(OH)D₃ to induce osteoblast differentiation of rBMMSCs. PI3K/AKT is at least partially involved in the regulation of CMA. These data indicate the importance of megalin in BMMSCs for vitamin D’s role in skeletal health.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02623-z.

Could Vitamin D Be Effective in Prevention of Preeclampsia?

Prevention of preeclampsia (PE) remains one of the most significant problems in perinatal medicine. Due to the possible unpredictable course of hypertension in pregnancy, primarily PE and the high complication rate for the mother and fetus/newborn, it is urgent to offer pregnant women in high-risk groups effective methods of preventing the PE development or delaying its appearance. In addition, due to the association of PE with an increased risk of developing cardiovascular diseases (CVD) in later life, effective preeclampsia prevention could also be important in reducing their incidence. Ideal PE prophylaxis should target the pathogenetic changes leading to the development of PE and be safe for the mother and fetus, inexpensive and freely available. Currently, the only recognized method of PE prevention recommended by many institutions around the world is the use of a small dose of acetylsalicylic acid in pregnant women with risk factors. Unfortunately, some cases of PE are diagnosed in women without recognized risk factors and in those in whom prophylaxis with acetylsalicylic acid is not adequate. Hence, new drugs which would target pathogenetic elements in the development of preeclampsia are studied. Vitamin D (Vit D) seems to be a promising agent due to its beneficial effect on placental implantation, the immune system, and angiogenic factors. Studies published so far emphasize the relationship of its deficiency with the development of PE, but the data on the benefits of its supplementation to reduce the risk of PE are inconclusive. In the light of current research, the key issue is determining the protective concentration of Vit D in a pregnant woman. The study aims to present the possibility of using Vit D to prevent PE, emphasizing its impact on the pathogenetic elements of preeclampsia development.

Low serum 1,25(OH)2D3 in end-stage renal disease: is reduced 1α-hydroxylase the only problem?

Low serum 1,25-dihydroxyvitamin D (1,25(OH)2D) in end-stage renal disease (ESRD) is considered a consequence of elevated fibroblast growth factor 23 (FGF23) and concomitant reduced activity of renal 1α-hydroxylase (CYP27B1). Current ESRD treatment strategies to increase serum calcium and suppress secondary hyperparathyroidism involve supplementation with vitamin D analogues that circumvent 1α-hydroxylase. This overlooks the potential importance of 25-hydroxyvitamin D (25(OH)D) deficiency as a contributor to low serum 1,25(OH)2D. We investigated the effects of vitamin D (cholecalciferol) supplementation (40,000 IU for 12 weeks and maintenance dose of 20,000 IU fortnightly), on multiple serum vitamin D metabolites (25(OH)D, 1,25(OH)2D3 and 24,25(OH)2D3) in 55 haemodialysis patients. Baseline and 12 month data were compared using related-samples Wilcoxon signed rank test. All patients remained on active vitamin D analogues as part of routine ESRD care. 1,25(OH)2D3 levels were low at baseline (normal range: 60-120 pmol/L). Cholecalciferol supplementation normalised both serum 25(OH)D and 1,25(OH)2D3. Median serum 25(OH)D increased from 35.1 nmol/L (IQR: 23.0-47.5 nmol/L) to 119.9 nmol/L (IQR: 99.5-143.3 nmol/L) (P < 0.001). Median serum 1,25(OH)2D3 and 24,25(OH)2D3 increased from 48.3 pmol/L (IQR: 35.9-57.9 pmol/L) and 3.8 nmol/L (IQR: 2.3-6.0 nmol/L) to 96.2 pmol/L (IQR: 77.1-130.6 pmol/L) and 12.3 nmol/L (IQR: 9-16.4 nmol/L), respectively (P < 0.001). A non-significant reduction in daily active vitamin D analogue dose occurred, 0.94 µmcg at baseline to 0.77 µmcg at 12 months (P = 0.73). The ability to synthesise 1,25(OH)2D3 in ESRD is maintained but is substrate dependent, and serum 25(OH)D was a limiting factor at baseline. Therefore, 1,25(OH)2D3 deficiency in ESRD is partly a consequence of 25(OH)D deficiency, rather than solely due to reduced 1α-hydroxylase activity as suggested by current treatment strategies.

Extended-release calcifediol in stage 3-4 chronic kidney disease: a new therapy for the treatment of secondary hyperparathyroidism associated with hypovitaminosis D

A high percentage of patients with chronic kidney disease have hypovitaminosis D, which is a driver of secondary hyperparathyroidism and an important factor in chronic kidney disease-mineral and bone disorder. Vitamin D deficiency (serum total 25-OH vitamin D levels < 30 ng/mL) occurs early in the course of chronic kidney disease and treatment guidelines recommend early intervention to restore 25-OH vitamin D levels as a first step to prevent/delay the onset/progression of secondary hyperparathyroidism. The vitamin D forms administered to replace 25-OH vitamin D include cholecalciferol, ergocalciferol, and immediate- or extended-release formulations of calcifediol. Most patients with intermediate-stage chronic kidney disease will develop secondary hyperparathyroidism before dialysis is required. Control of parathyroid hormone levels becomes a major focus of therapy in these patients. This article focuses on the position of extended-release calcifediol in the treatment of patients with stage 3–4 chronic kidney disease and secondary hyperparathyroidism with hypovitaminosis D. Several characteristics of extended-release calcifediol support its use in the intermediate stages of chronic kidney disease. The pharmacokinetics of extended-release calcifediol make it effective for replenishing 25-OH vitamin D levels, with minimal impact on vitamin D catabolism from fibroblast-growth factor-23 and CYP24A1 upregulation. Extended-release calcifediol increases circulating 25-OH vitamin D levels in a dose-dependent manner and lowers parathyroid hormone levels by a clinically relevant extent, comparable to what can be achieved by administering active vitamin D analogues, though with a lower risk of hypercalcaemia and hyperphosphataemia. Active vitamin D analogues are reserved for patients undergoing dialysis or pre-dialysis patients with severe progressive secondary hyperparathyroidism.

Circulatory 25(OH)D and 1,25(OH)2D as differential biomarkers between multiple system atrophy and Parkinson's disease patients

Background and purpose

There is sufficient evidence to support vitamin D's noncalcemic effects and the role of vitamin D deficiency in the development of a wide range of neurological disorders. This study aimed to evaluate whether serum 25(OH)D and 1,25(OH) 2 D could be used as biomarkers to differentiate between healthy subjects (HS), multiple system atrophy (MSA) and Parkinson's disease (PD) patients of both genders.

Methods

A total of 107 subjects were included in this study, divided into three groups: 1- HS (n = 61), 2- MSA patients (n = 19), and 3- PD patients (n = 27). The patients were assessed using UMSARS II, UPDRS III, H&Y, MMSE and MoCA rating scales. The levels of 25(OH)D and 1,25(OH) 2 D in serum were determined using the radioimmunoassay technique.

Results

The levels of 25(OH)D and 1,25(OH) 2 D in HS were 26.85 +/- 7.62 ng/mL and 53.63 +/- 13.66 pg/mL respectively. 25(OH)D levels were lower in both MSA and PD by 61% and 50%, respectively (P = 0.0001 vs. HS). 1,25(OH) 2 D levels were lower in MSA by 29%(P = 0.001 vs HS). There was a correlation between 25(OH)D and 1,25(OH) 2 D in MSA and PD, but not in HS. 1,25(OH) 2 D regressed with MMSE (β = 0.476, P = 0.04, R 2 = 0.226) in MSA, and with UPDRS III (β = -0.432, P = 0.024, R 2 = 0.187) and MoCA (β = 0.582, P = 0.005,R 2 = 0.279) in PD. 25(OH)D displayed considerable differentiative strength between HS and MSA (Wald = 17.123, OR = 0.586, P = 0.0001; AUC = 0.982, sensitivity and Youden index = 0.882, P = 0.0001) and PD (Wald = 18.552, OR = 0.700, P = 0.0001; AUC = 0.943, sensitivity = 0.889, YI = 0.791, P = 0.0001). 1,25(OH) 2 D distinguished MSA from PD (Wald 16.178, OR = 1.117, P = 0.0001; AUC = 0.868, sensitivity = 0.926, Youden index =0.632, P = 0.0001). H&Y exhibited the highest sensitivity, AUC, and significant distinguishing power between MSA and PD.

Conclusions

Serum 25(OH)D and 1,25(OH) 2 D could be useful biomarkers for MSA and PD. 25(OH)D and H&Y provided the highest sensitivity and group classification characteristics.

Vitamin D and COVID-19: An Overview of Recent Evidence

The novel coronavirus severe acute respiratory syndrome (SARS-CoV-2) has progressed rapidly from an outbreak to a global pandemic, with new variants rapidly emerging. Coronavirus disease 2019 (COVID-19), the disease resulting from SARS-CoV-2 infection, can lead to multiorgan damage. Due to the extremely contagious and fatal nature of the virus, it has been a priority of medical research to find effective means of treatment. Amid this search, the role of vitamin D in modulating various aspects of the innate and adaptive immune system has been discussed. This review aims to consolidate the research surrounding the role of vitamin D in the treatment and prevention of COVID-19. While there are some conflicting results reported, the consensus is that vitamin D has a host of immunomodulatory effects which may be beneficial in the context of COVID-19 and that low levels of vitamin D can result in dysfunction of crucial antimicrobial effects, potentially contributing to poor prognosis. Studies also show that the effects of low vitamin D can be mitigated via supplementation, although the benefits of vitamin D supplementation in the treatment of COVID-19 remain controversial.

A Novel Method for the Determination of Vitamin D Metabolites Assessed at the Blood-Cerebrospinal Fluid Barrier

The brain’s supply with vitamin D is poorly understood. Therefore, the present study aimed to determine 25-hydroxy vitamin D3 (25(OH)D) and 24,25-dihydroxy vitamin D (24,25(OH)₂D₃) in serum and cerebrospinal fluid (CSF) from individuals with intact and disturbed brain-CSF-barrier (BCB) function. In 292 pairs of serum and CSF samples the vitamin D metabolites were measured with liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). CSF/serum ratios (Q_ALB, Q_25(OH)D, Q_24,25(OH)2D3) were calculated. Median (IQR) serum concentrations of 25(OH)D and 24,25(OH)₂D₃ were 63.8 (43.4–83.9) nmol/L and 4.2 (2.2–6.2) nmol/L. The CSF concentrations of both metabolites accounted for 3.7 and 3.3% of the respective serum concentrations. Serum 25(OH)D correlated inversely with Q_25(OH)D and Q_24,25(OH)2D3 implying a more efficient transport of both metabolites across the BCB when the serum concentration of 25(OH)D is low. In patients with BCB dysfunction, the CSF concentrations and the CSF/serum ratios of both vitamin D metabolites were higher than in individuals with intact BCB. The CSF concentrations of 25(OH)D and 24,25(OH)₂D₃ depend on BCB function and the respective serum concentrations of both metabolites. Higher vitamin D metabolite concentrations in CSF of patients with impaired BCB function may be due to passive diffusion across the BCB.

20S-Hydroxyvitamin D3, a Secosteroid Produced in Humans, Is Anti-Inflammatory and Inhibits Murine Autoimmune Arthritis

The ability to use large doses of vitamin D3 (D3) to chronically treat autoimmune diseases such as rheumatoid arthritis (RA) is prohibitive due to its calcemic effect which can damage vital organs. Cytochrome P450scc (CYP11A1) is able to convert D3 into the noncalcemic analog 20S-hydroxyvitamin D3 [20S(OH)D3]. We demonstrate that 20S(OH)D3 markedly suppresses clinical signs of arthritis and joint damage in a mouse model of RA. Furthermore, treatment with 20S(OH)D3 reduces lymphocyte subsets such as CD4+ T cells and CD19+ B cells leading to a significant reduction in inflammatory cytokines. The ratio of T reg cells (CD4+CD25+Foxp3+ T cells) to CD3+CD4+ T cells is increased while there is a decrease in critical complement-fixing anti-CII antibodies. Since pro-inflammatory cytokines and antibodies against type II collagen ordinarily lead to destruction of cartilage and bone, their decline explains why arthritis is attenuated by 20(OH) D3. These results provide a basis for further consideration of 20S(OH)D3 as a potential treatment for RA and other autoimmune disorders.

Expression Analysis of VDR-Related LncRNAs in Autism Spectrum Disorder

Vitamin D receptor (VDR) signaling has been reported to affect neurodevelopment, thus participating in the risk of autism spectrum disorder (ASD). We have measured expression amounts of VDR, CYP27B1, and two related long non-coding RNAs, namely SNHG6 and LINC00511, in the circulation of ASD patients compared with normal controls. Expression of CYP27B1 was remarkably higher in ASD cases compared with controls (posterior beta = 2.38, SE = 0.46, adjusted P value < 0.0001, 95% credible interval (CrI) for beta = [1.49, 3.27]). Level of SNHG6 was lower in ASD cases compared with controls (posterior beta = - 0.791, SE = 0.24, adjusted P value = 0.029, 95% CrI for beta = [- 1.27, - 0.33]). Expression levels of VDR and LINC00511 were similar between ASD cases and controls (P values = 0.97 and 0.46, respectively). Expressions of VDR, CYP27B1, SNHG6, and LINC00511 were not correlated with age of children. However, significant correlations were perceived between expressions of CYP27B1 and LINC00511 (r = 0.47, P < 0.0001), VDR and CYP27B1 (r = 0.42, P < 0.0001), and VDR and SNHG6 (r = 0.32, P < 0.0001). Therefore, these results imply dysregulation of a number of VDR-related genes in ASD patients.

Nutritional management of diabetes mellitus during the pandemic of COVID-19: a comprehensive narrative review

Objectives

According to the recent epidemiological studies, patients with diabetes mellitus (DM) may be at higher risk of hospitalization due to COVID-19. Regarding the important role of nutrition on the immunity, the present review article aimed to outline nutritional support of DM during the outbreak of COVID-19 with a mechanistic insight.

Methods

Searches were performed in PubMed/MEDLINE, ScienceDirect, Scopus, and Google Scholar databases from 2000 until December 2020 using the following keywords. All relevant clinical and experimental studies published in English were included.

Results

Evidences revealed that hyperglycemia is a significant predictor of some viral infections including COVID-19 which can exacerbate the complications of DM. According to the literature review, adequate intake of dietary protein, fiber, essential fatty acids and some micronutrients especially vitamins D, C, B12, folate, zinc and selenium has beneficial effects on the prevention and treatment of COVID-19 in diabetic patients through modulation of innate and adaptive immune responses or direct effects on virus enzymes or the rate of cell entrance.

Conclusions

It is well understood that malnutrition may increase susceptibility to viral infections and disease progression. Therefore, considering nutritional status of diabetic patients and reasonable supplementation of the above mentioned nutrients can ameliorate the symptoms of COVID-19 in DM. However, further well-designed clinical trials are needed to determine their therapeutic dose.

Vitamin D Toxicity

Fortification of food products with vitamin D was central to the eradication of rickets in the early parts of the 20th century in the United States. In the subsequent almost 100 years since, accumulating evidence has linked vitamin D deficiency to a variety of outcomes, and this has paralleled greater public interest and awareness of the health benefits of vitamin D. Supplements containing vitamin D are now widely available in both industrialized and developing countries, and many are in the form of unregulated formulations sold to the public with little guidance for safe administration. Together, this has contributed to a transition whereby a dramatic global increase in cases of vitamin D toxicity has been reported. Clinicians are now faced with the challenge of managing this condition that can present on a spectrum from asymptomatic to acute life-threatening complications. This article considers contemporary data on vitamin D toxicity, and diagnostic and management strategies relevant to clinical practice.

Nutritional Support for Bariatric Surgery Patients: The Skin beyond the Fat

Body contouring surgery after the massive weight loss due to bariatric surgery deals with different kinds of complications. The aim of this review is to analyze the role that some nutrients may play in tissue healing after surgery, thus helping plastic surgeons to improve the aesthetic and health outcomes in massive weight loss patients under a multidisciplinary approach. As a matter of fact, preoperative nutritional deficiencies have been shown for vitamins and minerals in a large percentage of post-bariatric patients. Preoperative deficiencies mainly concern iron, zinc, selenium, and vitamins (both fat-soluble and water-soluble), but also total protein. During the postoperative period, these problems may increase because of the patients' very low intake of vitamins and minerals after bariatric surgery (below 50% of the recommended dietary allowance) and the patients' low compliance with the suggested multivitamin supplementation (approximately 60%). In the postoperative period, more attention should be given to nutritional aspects in regard to the length of absorptive area and the percentage of weight loss.

Vitamin D protects glomerular mesangial cells from high glucose-induced injury by repressing JAK/STAT signaling

Aim

High glucose (HG) induces the production of transforming growth factor (TGF)-β and reactive oxygen species, which further activates JAK/STAT signaling and promotes the synthesis of matrix proteins, contributes to the pathophysiological processes of diabetic nephropathy. This study aims to investigate the protection role of vitamin D (VD) in the kidney in high glucose condition.

Methods

Rat glomerular mesangial cells were cultured in high glucose medium, with or without VD or VD receptor (VDR) siRNAs treatment. The levels of TGF-β and fibronectin were detected by qRT-PCR, immunoblotting and enzyme-linked immunosorbent assay (ELISA). The levels of phosphorylated JAK2, STAT1 and STAT3, and JAK/STAT signaling downstream genes were examined by immunoblotting and qRT-PCR.

Results

In rat glomerular mesangial cells, VD treatment can repress the tyrosine phosphorylation of JAK2, STAT1 and STAT3. VD inhibited TGF-β and fibronectin expression which was rescued by vitamin d receptor (VDR) siRNA and STATs inhibitor perficitinib. The JAK/STAT signaling downstream protein coding genes including SOCS1, SOCS3 and type IV collagen were repressed by VD. Meanwhile, the expression of non-coding RNAs such as miR-181a, miR-181b, was repressed by VD, and the expression of miR-34a and Let-7b was upregulated by VD.

Conclusion

Vitamin D (VD) treatment inhibits the function of HG on fibronectin production through regulating JAK/STAT pathway. These results provide direct evidences that VD protects glomerular mesangial cells from high glucose-induced injury through repressing JAK/STAT signaling, which has the potential for clinical DN treatment.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11255-020-02728-z.

Implications of Vitamin D Research in Chickens can Advance Human Nutrition and Perspectives for the Future

The risk of vitamin D insufficiency in humans is a global problem that requires improving ways to increase vitamin D intake. Supplements are a primary means for increasing vitamin D intake, but without a clear consensus on what constitutes vitamin D sufficiency, there is toxicity risk with taking supplements. Chickens have been used in many vitamin-D-related research studies, especially studies involving vitamin D supplementation. Our state-of-the-art review evaluates vitamin D metabolism and how the different hydroxylated forms are synthesized. We provide an overview of how vitamin D is absorbed, transported, excreted, and what tissues in the body store vitamin D metabolites. We also discuss a number of studies involving vitamin D supplementation with broilers and laying hens. Vitamin D deficiency and toxicity are also described and how they can be caused. The vitamin D receptor (VDR) is important for vitamin D metabolism; however, there is much more to understand about VDR in chickens. Potential research aims involving vitamin D and chickens should explore VDR mechanisms that could lead to newer insights into VDR. Utilizing chickens in future research to help elucidate vitamin D mechanisms has great potential to advance human nutrition. Finding ways to increase vitamin D intake will be necessary because the coronavirus disease 2019 (COVID-19) pandemic is leading to increased risk of vitamin D deficiency in many populations. Chickens can provide a dual purpose with addressing pandemic-caused vitamin D deficiency: 1) vitamin D supplementation gives chickens added-value with the possibility of leading to vitamin-D-enriched meat and egg products; and 2) using chickens in research provides data for translational research. We believe expanding vitamin-D-related research in chickens to include more nutritional aims in vitamin D status has great implications for developing better strategies to improve human health.

New Roles for Vitamin D Superagonists: From COVID to Cancer

Vitamin D is a potent steroid hormone that induces widespread changes in gene expression and controls key biological pathways. Here we review pathophysiology of vitamin D with particular reference to COVID-19 and pancreatic cancer. Utility as a therapeutic agent is limited by hypercalcemic effects and attempts to circumvent this problem have used vitamin D superagonists, with increased efficacy and reduced calcemic effect. A further caveat is that vitamin D mediates multiple diverse effects. Some of these (anti-fibrosis) are likely beneficial in patients with COVID-19 and pancreatic cancer, whereas others (reduced immunity), may be beneficial through attenuation of the cytokine storm in patients with advanced COVID-19, but detrimental in pancreatic cancer. Vitamin D superagonists represent an untapped resource for development of effective therapeutic agents. However, to be successful this approach will require agonists with high cell-tissue specificity.

Pathophysiological Implication of Vitamin D in Diabetic Kidney Disease

BACKGROUND

Vitamin D is a hormone regulating not only calcium and phosphate homeostasis but also, at the same time, exerting many other extraskeletal functions via genomic effects (gene transcription) and probably by non-genomic effects as well. Availability is ensured by dietary intake of its precursors and by de novo production via sunlight. Yet, vitamin D deficiency and insufficiency are very common across the globe and are connected to many pathophysiological states, for example, diabetes mellitus, allergies, autoimmune diseases, pregnancy complications, and recently have also been associated with worse COVID-19 clinical outcomes.

SUMMARY

In this review, we summarize current knowledge about vitamin D metabolism in general, its role in diabetes mellitus (mainly type 2) and diabetic complications (mainly diabetic kidney disease), and potential therapeutic perspectives including vitamin D signalling as a druggable target. Key Messages: Vitamin D is not only a vitamin but also a hormone involved in many physiological processes. Its insufficiency or deficiency can lead to many pathological states.

Vitamin D and Acute Kidney Injury: A Two-Way Causality Relation and a Predictive, Prognostic, and Therapeutic Role of Vitamin D

Background: Acute kidney injury (AKI) constitutes a multi-factorially caused condition, which significantly affects kidney function and can lead to elevated risk of morbidity and mortality. Given the rising scientific evidence regarding vitamin D's (VitD's) multisystemic role, the connection between AKI and VitD is currently being studied, and the complex relation between them has started to be unraveled.

Methods: A systematic review had been conducted to identify the pathogenetic relation of VitD and AKI and the potential role of VitD as a biomarker and therapeutic–renoprotective factor.

Results: From 792 articles, 74 articles were identified that fulfilled the inclusion criteria. Based on these articles, it has been found that not only can VitD disorders (VitD deficiency or toxicity) cause AKI but, also, AKI can lead to great disruption in the metabolism of VitD. Moreover, it has been found that VitD serves as a novel biomarker for prediction of the risk of developing AKI and for the prognosis of AKI's severity. Finally, animal models showed that VitD can both ameliorate AKI and prevent its onset, suggesting its renoprotective effect.

Conclusion: There is a complex two-way pathogenetic relation between VitD disorders and AKI, while, concomitantly, VitD serves as a potential novel predictive–prognostic biomarker and a treatment agent in AKI therapy.

Vitamin D receptor gene polymorphisms and haplotypes in the etiology of recurrent miscarriages

A few years ago it was shown that disturbed metabolism of the vitamin D/receptor (VD/VDR) complex may be important in the etiology of spontaneous abortion, as well as in the etiology of recurrent miscarriages (RM). The goal of this study was to investigate the association between four maternal VDR polymorphisms as well as haplotypes settings and RM occurrence in a Polish population of women in reproductive age. A total of 230 women were recruited to this study (110 with RM, 120 consecutively recruited age-matched healthy women with at least two full-term pregnancies and with no history of miscarriages). DNA samples were genotyped for VDR polymorphisms: FokI (rs2228570), BsmI (rs1544410), ApaI (rs7975232) and TaqI (rs731236). Significant differences in genotype distributions and allele frequencies between case and control groups were observed in VDR BsmI polymorphism (GG vs. GA and AA, OR = 0.56, p = 0.036 and OR = 1.49, p = 0.035, respectively). The best evidence of an association with RM prevention was observed for the TTGT haplotype, which was more frequent among controls than cases even after permutation test (0.09 vs. 0.017, p = 0.0024). Other haplotypes were also significantly more frequent in the control group: TGT (rs7975232, rs1544410, rs2228570), TG (rs7975232, rs1544410), TTG (rs731236, rs7975232, rs1544410), TT (rs731236, rs7975232). Our research indicated the possible role of VDR BsmI genetic polymorphism in RM etiology, suggesting at the same time the active role of maternal VD metabolism and its influence on pregnancy outcome. The significant influence of several maternal haplotypes was shown to prevent RM occurrence.

Cholecalciferol (vitamin D3) has a direct protective activity against interleukin 6-induced atrophy in C2C12 myotubes

We previously determined that different vitamin D metabolites can have opposite effects on C2C12 myotubes, depending on the sites of hydroxylation or doses. Specifically, 25(OH)D₃ (25VD) has an anti-atrophic activity, 1,25(OH)₂D₃ induces atrophy, and 24,25(OH)₂D₃ is anti-atrophic at low concentrations and atrophic at high concentrations. This study aimed to clarify whether cholecalciferol (VD3) too, the non-hydroxylated upstream metabolite, has a direct effect on muscle cells.

Assessing the effects of VD3 treatment on mouse C2C12 skeletal muscle myotubes undergoing atrophy induced by interleukin 6 (IL6), we demonstrated that VD3 has a protective action, preserving C2C12 myotubes size, likely through promoting the differentiation and fusion of residual myoblasts and by modulating the IL6-induced autophagic flux. The lack, in C2C12 myotubes, of the hydroxylase transforming VD3 in the anti-atrophic 25VD metabolite suggests that VD3 may have a direct biological activity on the skeletal muscle. Furthermore, we found that the protective action of VD3 depended on VDR, implying that VD3 too might bind to and activate VDR. However, despite the formation of VDR-RXR heterodimers, VD3 effects do not depend on RXR activity.

In conclusion, VD3, in addition to its best-known metabolites, may directly impact on skeletal muscle homeostasis.

Role of 25-Hydroxyvitamin D3 and 1,25-Dihydroxyvitamin D3 in Chicken Embryo Osteogenesis, Adipogenesis, Myogenesis, and Vitamin D3 Metabolism

A study was conducted to understand the effects of 25-hydroxyvitamin D₃ (25OHD) and 1,25-dihydroxyvitamin D₃ (1,25OHD) administration on the expression of key genes related to osteogenesis, adipogenesis, myogenesis, and vitamin D₃ metabolism in the chicken embryo. A total of 120 fertilized Cobb 500 eggs were used in the current study and were reared under standard incubation conditions. On embryonic day 3 (ED 3), PBS (C), PBS with 40ng 1,25OHD (1,25D-L), 200ng 1,25OHD (1,25D-H), 40ng 25OHD (25D-L), or 200ng 25OHD (25D-H) were injected into the dorsal vein of developing embryos. Whole embryos were harvested at 1, 3, and 6h post-injection for gene expression analyses (n=8). Gene expression for key osteogenesis markers (RUNX2: runt-related transcription factor 2; BMP2: bone morphogenetic protein 2; COL1A2: collagen type I alpha 2 chain; BGLAP: bone gamma-carboxyglutamate protein; SPP1: secreted phosphoprotein 1; and ALP: alkaline phosphatese), adipogenesis markers (PPAR-γ: peroxisome proliferator-activated receptor gamma; FASN: fatty acid synthase; and FABP4: fatty acid binding protein 4), myogenesis markers (MYOG: myogenin; MYOD1: myogenic differentiation 1; and MYF5: myogenic factor 5), and the enzyme responsible for vitamin D₃ inactivation (CYP24A1: cytochrome P450 family 24 subfamily A member 1) were measured using real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR). Data were normalized by the ΔΔCT method and analyzed using a one-way ANOVA. Results indicated that at 1h post-injection, no differences were found among treatments. At 3h, the early osteogenesis differentiation marker, ALP, was increased by 1,25D-H and 25D-H, and 25D-H also stimulated the expression of adipogenesis markers (FAPB4 and FASN). In contrast, the expression of myogenesis markers (MYOD1 and MYF5) was suppressed by 25OHD or 1,25OHD treatments, respectively. At 6h, a late osteogenic differentiation marker, SPP1, was increased by 25D-H. MYOD1 and MYF5 were continuously suppressed by 25OHD treatments or 1,25D-H. The evidence of vitamin D₃ metabolite retention was assessed by measuring CYP24A1 expression. At 1h, there were no differences in CYP24A1 expression. At 3h, all treatments upregulated CYP24A1 expression relative to control (PBS) embryos. However, at 6h, only the 25D-H group retained higher CYP24A1 expression compared to the other treatments. In conclusion, the results suggested both 1,25OHD and 25OHD induced chicken embryo osteogenesis and adipogenesis, but inhibited myogenesis during early chicken embryo development. The higher dosage of 25OHD showed a possibility of a longer retention time in the embryos.

Genomic Mechanisms Governing Mineral Homeostasis and the Regulation and Maintenance of Vitamin D Metabolism

Our recent genomic studies identified a complex kidney‐specific enhancer module located within the introns of adjacent Mettl1 (M1) and Mettl21b (M21) genes that mediate basal and PTH induction of Cyp27b1, as well as suppression by FGF23 and 1,25‐dihydroxyvitamin D₃ [1,25(OH)₂D₃]. The tissue specificity for this regulatory module appears to be localized exclusively to renal proximal tubules. Gross deletion of these segments in mice has severe consequences on skeletal health, and directly affects Cyp27b1 expression in the kidney. Deletion of both the M1 and M21 submodules together almost completely eliminates basal Cyp27b1 expression in the kidney, creating a renal specific pseudo‐null mouse, resulting in a systemic and skeletal phenotype similar to that of the Cyp27b1‐KO mouse caused by high levels of both 25‐hydroxyvitamin D₃ [25(OH)D₃] and PTH and depletion of 1,25(OH)₂D₃. Cyp24a1 levels in the double KO mouse also decrease because of compensatory downregulation of the gene by elevated PTH and reduced FGF23 that is mediated by an intergenic module located downstream of the Cyp24a1 gene. Outside of the kidney in nonrenal target cells (NRTCs), expression of Cyp27b1 in these mutant mice was unaffected. Dietary normalization of calcium, phosphate, PTH, and FGF23 rescues the aberrant phenotype of this mouse and normalizes the skeleton. In addition, both the high levels of 25(OH)D₃ were reduced and the low levels of 1,25(OH)₂D₃ were fully eliminated in these mutant mice as a result of the rescue‐induced normalization of renal Cyp24a1. Thus, these hormone‐regulated enhancers for both Cyp27b1 and Cyp24a1 in the kidney are responsible for the circulating levels of 1,25(OH)₂D₃ in the blood. The retention of Cyp27b1 and Cyp24a1 expression in NRTCs of these endocrine 1,25(OH)₂D₃‐deficient mice suggests that this Cyp27b1 pseudo‐null mouse will provide a model for the future exploration of the role of NRTC‐produced 1,25(OH)₂D₃ in the hormone's diverse noncalcemic actions in both health and disease. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Effect of vitamin D3 on the osteogenic differentiation of human periodontal ligament stromal cells under inflammatory conditions

Objectives

Vitamin D₃ is known to activate osteogenic differentiation of human periodontal ligament stromal cells (hPDLSCs). Recently, inflammatory stimuli were shown to inhibit the transcriptional activity of hPDLSCs, but their effect on vitamin D₃‐induced osteogenic differentiation is not known. The present study aimed to investigate whether the effects of 1,25‐dihydroxvitamin D₃ (1,25(OH)₂D₃) and 25‐hydroxvitamin D₃ (25(OH)D₃) on the osteogenic differentiation of hPDLSCs are also altered under inflammatory conditions. Furthermore, the expression of osteogenesis‐related factors by hPDLSCs under osteogenic conditions was assessed in the presence of inflammatory stimuli.

Materials and Methods

Primary hPDLSCs of six donors were cultured in osteogenic induction medium containing either 1,25(OH)₂D₃ (0‐10 nM) or 25(OH)D₃ (0‐100 nM) in the presence and absence of Porphyromonas gingivalis lipopolysaccharide (LPS) or Pam3CSK4 for 7, 14 and 21 days. Osteogenic differentiation of hPDLSCs was evaluated by analysis of mineralization as assessed by Alizarin Red S staining and gene expression levels of osteogenesis‐related factors osteocalcin, osteopontin and runt‐related transcription factor 2 (RUNX2) were analysed with qPCR.

Results

Treatment with 1,25(OH)₂D₃ significantly enhanced the osteogenic differentiation of hPDLSCs and their expression of osteocalcin and osteopontin. The 1,25(OH)₂D₃‐triggered expression of osteogenesis‐related factors was significantly lower in the presence of Pam3CSK4, but not P. gingivalis LPS. None of the inflammatory stimuli had significant effects on the 1,25(OH)₂D₃‐induced osteogenic differentiation. 25(OH)D₃ neither affected gene expression levels nor osteogenic differentiation of hPDLSCs cultured in osteogenic induction medium.

Conclusion

The results of this study indicate that inflammatory stimuli also diminish the 1,25(OH)₂D₃‐induced expression of osteogenesis‐related factors in hPDLSCs under osteogenic conditions, while having no effect on the osteogenic differentiation.

Vitamin D-regulated Gene Expression Profiles: Species-specificity and Cell-specific Effects on Metabolism and Immunity

Vitamin D has pleiotropic physiological actions including immune system regulation, in addition to its classical role in calcium homeostasis. Hormonal 1,25-dihydroxyvitamin D (1,25D) signals through the nuclear vitamin D receptor, and large-scale expression profiling has provided numerous insights into its diverse physiological roles. To obtain a comprehensive picture of vitamin D signaling, we analyzed raw data from 94 (80 human, 14 mouse) expression profiles of genes regulated by 1,25D or its analogs. This identified several thousand distinct genes directly or indirectly up- or downregulated in a highly cell-specific manner in human cells using a 1.5-fold cut-off. There was significant overlap of biological processes regulated in human and mouse but minimal intersection between genes regulated in each species. Disease ontology clustering confirmed roles for 1,25D in immune homeostasis in several human cell types, and analysis of canonical pathways revealed novel and cell-specific roles of vitamin D in innate immunity. This included cell-specific regulation of several components of Nucleotide-binding Oligomerization Domain-like (NOD-like) pattern recognition receptor signaling, and metabolic events controlling innate immune responses. Notably, 1,25D selectively enhanced catabolism of branched-chain amino acids (BCAAs) in monocytic cells. BCAA levels regulate the major metabolic kinase mammalian Target of Rapamycin (mTOR), and pretreatment with 1,25D suppressed BCAA-dependent activation of mTOR signaling. Furthermore, ablation of BCAT1 expression in monocytic cells blocked 1,25D-induced increases in autophagy marker LAMP1. In conclusion, the data generated represents a powerful tool to further understand the diverse physiological roles of vitamin D signaling and provides multiple insights into mechanisms of innate immune regulation by 1,25D.

Vitamin D and Immune Regulation: Antibacterial, Antiviral, Anti-Inflammatory

Regulation of immune function continues to be one of the most well-recognized extraskeletal actions of vitamin D. This stemmed initially from the discovery that antigen presenting cells such as macrophages could actively metabolize precursor 25-hydroxyvitamin D (25D) to active 1,25-dihydroxyvitamin D (1,25D). Parallel observation that activated cells from the immune system expressed the intracellular vitamin D receptor (VDR) for 1,25D suggested a potential role for vitamin D as a localized endogenous modulator of immune function. Subsequent studies have expanded our understanding of how vitamin D exerts effects on both the innate and adaptive arms of the immune system. At an innate level, intracrine synthesis of 1,25D by macrophages and dendritic cells stimulates expression of antimicrobial proteins such as cathelicidin, as well as lowering intracellular iron concentrations via suppression of hepcidin. By potently enhancing autophagy, 1,25D may also play an important role in combatting intracellular pathogens such as M. tuberculosis and viral infections. Local synthesis of 1,25D by macrophages and dendritic cells also appears to play a pivotal role in mediating T-cell responses to vitamin D, leading to suppression of inflammatory T helper (Th)1 and Th17 cells, and concomitant induction of immunotolerogenic T-regulatory responses. The aim of this review is to provide an update on our current understanding of these prominent immune actions of vitamin D, as well as highlighting new, less well-recognized immune effects of vitamin D. The review also aims to place this mechanistic basis for the link between vitamin D and immunity with studies in vivo that have explored a role for vitamin D supplementation as a strategy for improved immune health. This has gained prominence in recent months with the global coronavirus disease 2019 health crisis and highlights important new objectives for future studies of vitamin D and immune function. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Vitamin D metabolites and the gut microbiome in older men

The vitamin D receptor is highly expressed in the gastrointestinal tract where it transacts gene expression. With current limited understanding of the interactions between the gut microbiome and vitamin D, we conduct a cross-sectional analysis of 567 older men quantifying serum vitamin D metabolites using LC-MSMS and defining stool sub-Operational Taxonomic Units from16S ribosomal RNA gene sequencing data. Faith's Phylogenetic Diversity and non-redundant covariate analyses reveal that the serum 1,25(OH)2D level explains 5% of variance in α-diversity. In β-diversity analyses using unweighted UniFrac, 1,25(OH)2D is the strongest factor assessed, explaining 2% of variance. Random forest analyses identify 12 taxa, 11 in the phylum Firmicutes, eight of which are positively associated with either 1,25(OH)2D and/or the hormone-to-prohormone [1,25(OH)2D/25(OH)D] "activation ratio." Men with higher levels of 1,25(OH)2D and higher activation ratios, but not 25(OH)D itself, are more likely to possess butyrate producing bacteria that are associated with better gut microbial health.

Vitamin D: Brain and Behavior

It has been 20 years since we first proposed vitamin D as a "possible" neurosteroid.^{( 1 )} Our work over the last two decades, particularly results from our cellular and animal models, has confirmed the numerous ways in which vitamin D differentiates the developing brain. As a result, vitamin D can now confidently take its place among all other steroids known to regulate brain development.^{( 2 )} Others have concentrated on the possible neuroprotective functions of vitamin D in adult brains. Here these data are integrated, and possible mechanisms outlined for the various roles vitamin D appears to play in both developing and mature brains and how such actions shape behavior. There is now also good evidence linking gestational and/or neonatal vitamin D deficiency with an increased risk of neurodevelopmental disorders, such as schizophrenia and autism, and adult vitamin D deficiency with certain degenerative conditions. In this mini-review, the focus is on what we have learned over these past 20 years regarding the genomic and nongenomic actions of vitamin D in shaping brain development, neurophysiology, and behavior in animal models. © 2020 The Author. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Dysregulation of vitamin D synthesis pathway genes in colorectal cancer: A case-control study

Background

The cytochromes P450 are a superfamily of enzymes that control the synthesis of the biologically active form of vitamin D, 1,25‐dihydroxyvitamin D3. These enzymes contribute to the formation of 1,25‐dihydroxyvitamin D3, which starts with a 25‐hydroxylation by CYP2R1 and CYP27A1 and a subsequent 1α‐hydroxylation via CYP27B1.

Methods

By using quantitative real‐time polymerase chain reaction (qRT‐PCR), we analyzed the expression ratio of CYP2R1, CYP27A1 and CYP27B1 genes within the vitamin D metabolic pathway in a total of 75 colorectal cancer (CRC) tissues compared to the adjacent tissues. Furthermore, we evaluated the association of CYP27B1 rs4646536 and CYP2R1 rs12794714 and rs10766196 polymorphisms with CRC risk in a total of 490 subjects, including 245 CRC patients and 245 non‐cancer controls. The genotyping was performed using tetra‐primer amplification refractory mutation system polymerase chain reaction (TP‐ARMS–PCR) method.

Results

The results indicated 2.3 and 2.7 upregulation of CYP2R1 and CYP27B1 genes in colorectal cancer tissues compared to the adjacent tissues, respectively. Rs12794714 AG genotype increased the risk of CRC (P = .03). Furthermore, a significant association was observed under the dominant inheritance model (P = .039).

Conclusion

CYP2R1 and CYP27B1 genes were over‐expressed in CRC samples compared to the adjacent control tissues. Furthermore, CYP2R1 rs12794714 variant was associated with the risk of CRC in the studied samples. CYP2R1 rs10766196 and CYP27B1 rs4646536 are not responsible for CYP2R1 and CYP27B1 genes expression alteration, respectively, but CYP2R1 rs12794714 polymorphism may be the reason of CYP2R1 upregulation and increased the risk of CRC.

Understanding the Biological Activities of Vitamin D in Type 1 Neurofibromatosis: New Insights into Disease Pathogenesis and Therapeutic Design

Vitamin D is a fat-soluble steroid hormone playing a pivotal role in calcium and phosphate homeostasis as well as in bone health. Vitamin D levels are not exclusively dependent on food intake. Indeed, the endogenous production-occurring in the skin and dependent on sun exposure-contributes to the majority amount of vitamin D present in the body. Since vitamin D receptors (VDRs) are ubiquitous and drive the expression of hundreds of genes, the interest in vitamin D has tremendously grown and its role in different diseases has been extensively studied. Several investigations indicated that vitamin D action extends far beyond bone health and calcium metabolism, showing broad effects on a variety of critical illnesses, including cancer, infections, cardiovascular and autoimmune diseases. Epidemiological studies indicated that low circulating vitamin D levels inversely correlate with cutaneous manifestations and bone abnormalities, clinical hallmarks of neurofibromatosis type 1 (NF1). NF1 is an autosomal dominant tumour predisposition syndrome causing significant pain and morbidity, for which limited treatment options are available. In this context, vitamin D or its analogues have been used to treat both skin and bone lesions in NF1 patients, alone or combined with other therapeutic agents. Here we provide an overview of vitamin D, its characteristic nutritional properties relevant for health benefits and its role in NF1 disorder. We focus on preclinical and clinical studies that demonstrated the clinical correlation between vitamin D status and NF1 disease, thus providing important insights into disease pathogenesis and new opportunities for targeted therapy.

Ferrotoxicity and its amelioration by endogenous vitamin D in experimental acute kidney injury

This work provides in-depth insights on catalytic iron-induced cytotoxicity and the resultant triggering of endogenous vitamin D synthesis in experimental acute kidney injury. Our results reveal significantly elevated levels of catalytic iron culminating in oxidant-mediated renal injury and a concomitant increase in 1,25-dihdyroxyvitamin D3 levels. Also, changes in other iron-related proteins including transferrin, ferritin, and hepcidin were observed both in the serum as well as in their mRNA expression. We consider all these findings vital since no connection between catalytic iron and vitamin D has been established so far. Furthermore, we believe that this work provides new and interesting results, with catalytic iron emerging as an important target in ameliorating renal cellular injury, possibly by timely administration of vitamin D. It also needs to be seen if these observations made in rats could be translated to humans by means of robust clinical trials.

Can Brain Health Be Supported by Vitamin D-Based Supplements? A Critical Review

This review presents recent knowledge on the neuroprotective effects of vitamin D and their usefulness as oral supplementation when combined with other molecules, such as curcumin. A critical look at the effectiveness of vitamin D in this field is also provided. Vitamin D plays a crucial role in neuroprotection and in the cognitive decline associated with aging, where vitamin D’s levels are related to the levels of several neurotrophic factors. An important role of vitamin D has also been observed in the mechanism of neuroinflammation, which is the basis of several aging conditions, including cognitive decline and neurodegeration; furthermore, the neuroprotective effect of vitamin D in the cognitive decline of aging has recently been reported. For this reason, many food supplements created for humans contain vitamin D alone or combined with other molecules with antioxidant properties. However, recent studies also explored negative consequences of the use at a high dosage of vitamin D. Vitamin D in tissues or brain cells can also modulate calbindin-D28K, parvalbumin, and calretinin, and is involved in immune function, thanks also to the combination with curcumin. Curcumin acts as a free radical scavenger and antioxidant, inhibiting lipid peroxidation and oxidative DNA damage. In particular, curcumin is a potent immune-regulatory agent and its administration has been reported to attenuate cognitive impairments. These effects could be exploited in the future to control the mechanisms that lead to the brain decay typical of neurodegenerative diseases.

Vitamin D Metabolism and Profiling in Veterinary Species

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

Prediagnostic Circulating Concentrations of Vitamin D Binding Protein and Survival among Patients with Colorectal Cancer

BACKGROUND

Higher total 25-hydroxyvitamin D [25(OH)D] levels are associated with improved survival among patients with colorectal cancer, but the relationships between circulating vitamin D binding protein (VDBP), and bioavailable or free 25(OH)D, and colorectal cancer survival remain unknown.

METHODS

We examined the associations between prediagnostic plasma levels of vitamin D-related markers and survival among 603 White participants diagnosed with colorectal cancer from two prospective U.S. cohorts. Plasma VDBP and total 25(OH)D were directly measured, while bioavailable and free 25(OH)D was calculated using a validated formula on the basis of total 25(OH)D, VDBP, and albumin levels. Cox proportional hazards regression was used to estimate HRs for overall and colorectal cancer-specific mortality, with adjustment for other prognostic markers and potential confounders.

RESULTS

Higher VDBP levels were associated with improved overall (P _trend = 0.001) and colorectal cancer-specific survival (P _trend = 0.02). Compared with patients in the lowest quartile, those in the highest quartile of VDBP had a multivariate HR of 0.58 [95% confidence interval (CI), 0.41-0.80] for overall mortality and 0.58 (95% CI, 0.37-0.91) for colorectal cancer-specific mortality. The results remained similar after further adjustment for total 25(OH)D levels. In contrast, neither bioavailable nor free 25(OH)D levels were associated with overall or colorectal cancer-specific mortality (all P _trend > 0.15).

CONCLUSIONS

Prediagnostic circulating concentrations of VDBP were positively associated with survival among patients with colorectal cancer.

IMPACT

The clinical utility of VDBP as a prognostic marker warrants further exploration, as well as research into underlying mechanisms of action.

The Molecular Mechanisms by Which Vitamin D Prevents Insulin Resistance and Associated Disorders

Numerous studies have shown that vitamin D deficiency is very common in modern societies and is perceived as an important risk factor in the development of insulin resistance and related diseases such as obesity and type 2 diabetes (T2DM). While it is generally accepted that vitamin D is a regulator of bone homeostasis, its ability to counteract insulin resistance is subject to debate. The goal of this communication is to review the molecular mechanism by which vitamin D reduces insulin resistance and related complications. The university library, PUBMED, and Google Scholar were searched to find relevant studies to be summarized in this review article. Insulin resistance is accompanied by chronic hyperglycaemia and inflammation. Recent studies have shown that vitamin D exhibits indirect antioxidative properties and participates in the maintenance of normal resting ROS level. Appealingly, vitamin D reduces inflammation and regulates Ca²⁺ level in many cell types. Therefore, the beneficial actions of vitamin D include diminished insulin resistance which is observed as an improvement of glucose and lipid metabolism in insulin-sensitive tissues.

Is there an association between serum 25(OH)D3 and mental well-being in patients with type 2 diabetes? Results from a cohort study in primary care

PURPOSE

There are limited and inconsistent results on the correlation between vitamin D and mental health in patients with type 2 diabetes (T2D). Thus, our aim was to explore the association between vitamin D and mental well-being in a community-based sample of participants with T2D.

METHODS

We analyzed serum 25-hydroxyvitamin D₃ (25(OH)D₃) in 698 patients with T2D at the baseline examination. The cohort was reinvestigated after 4 years. Data from SF-36 questionnaires measuring vitality and mental health at baseline and after 4 years were used for analyses.

RESULTS

Serum 25(OH)D₃ was inversely associated with poor mental health at baseline (odds ratio (OR) for 10 nmol/l increase in 25(OH)D₃, 0.90 (95% confidence interval (CI) 0.83-0.96, p = 0.003)) but not at follow-up (p > 0.05). Serum 25(OH)D₃ was not associated with vitality at baseline (p > 0.05). At follow-up, there was an inverse association between 25(OH)D₃ and low vitality (OR for 10 nmol/l increase in 25(OH)D₃, 0.89 (95% CI 0.82-0.97, p = 0.009)) but not after adjustment.

CONCLUSION

We found an inverse association between 25(OH)D₃ and mental health in patients with T2D at baseline. We found no association between 25(OH)D₃ and vitality after adjustment. Future studies are needed to determine the association between vitamin D and mental well-being in patients with T2D.

Vitamin D Attenuates Hypoxia-Induced Injury in Rat Primary Neuron Cells through Downregulation of the Dual Oxidase 1 (DUOX1) Gene

BACKGROUND This study aimed to investigate the mechanisms underlying the neuroprotective effects of vitamin D. MATERIAL AND METHODS Rat primary neuron cells were incubated under a hypoxia condition [a hypoxic chamber mixed with anaerobic gas (90% N₂, 5% CO₂) and 5% O₂] to induce cell injury. Cell transfection was performed to overexpress or suppress the expression of dual oxidase 1 (DUOX1). The malondialdehyde (MDA) and superoxide dismutase (SOD) levels were detected using a MDA (A003-2) or SOD (A001-1) kit. DUOX1 mRNA levels were detected using RT-PCR. Hypoxia-inducible factor-1alpha (HIF-1alpha), DUOX1, vitamin D receptor (VDR), NF-kappaB protein expressions were determined by western blotting. Cell apoptosis and reactive oxygen species (ROS) were evaluated by flow cytometry. RESULTS ROS increased significantly after hypoxic treatment. The expressions of HIF-1alpha and DUOX1 were significantly increased after hypoxic treatment. Vitamin D could decrease ROS level, apoptotic neuron cells and DUOX1 expression, and increase VDR expression. Downregulation of DUOX1 significantly decreased MDA level and apoptotic percentages of neuron cells, increased SOD level, and counteracted the hypoxia-induced increase of NF-kappaB signal. Further study showed that overexpression of DUOX1 significantly increased MDA level, ROS level, apoptotic percentages of neuron cells, and NF-kappaB nuclear signaling, while decreased SOD level. Vitamin D significantly counteracted the effects of DUOX1 overexpression induced injury in rat primary neuron cells. CONCLUSIONS Our study indicated that vitamin D may protect neuron cells from hypoxia-induced injury by regulating DUOX1 via the NF-kappaB signaling pathway.

Impact of the Local Inflammatory Environment on Mucosal Vitamin D Metabolism and Signaling in Chronic Inflammatory Lung Diseases

Vitamin D plays an active role in the modulation of innate and adaptive immune responses as well as in the protection against respiratory pathogens. Evidence for this immunomodulatory and protective role is derived from observational studies showing an association between vitamin D deficiency, chronic airway diseases and respiratory infections, and is supported by a range of experimental studies using cell culture and animal models. Furthermore, recent intervention studies have now shown that vitamin D supplementation reduces exacerbation rates in vitamin D-deficient patients with chronic obstructive pulmonary disease (COPD) or asthma and decreases the incidence of acute respiratory tract infections. The active vitamin D metabolite, 1,25-dihydroxy-vitamin D (1,25(OH)₂D), is known to contribute to the integrity of the mucosal barrier, promote killing of pathogens (via the induction of antimicrobial peptides), and to modulate inflammation and immune responses. These mechanisms may partly explain its protective role against infections and exacerbations in COPD and asthma patients. The respiratory mucosa is an important site of local 1,25(OH)₂D synthesis, degradation and signaling, a process that can be affected by exposure to inflammatory mediators. As a consequence, mucosal inflammation and other disease-associated factors, as observed in e.g., COPD and asthma, may modulate the protective actions of 1,25(OH)₂D. Here, we discuss the potential consequences of various disease-associated processes such as inflammation and exposure to pathogens and inhaled toxicants on vitamin D metabolism and local responses to 1,25(OH)₂D in both immune- and epithelial cells. We furthermore discuss potential consequences of disturbed local levels of 25(OH)D and 1,25(OH)₂D for chronic lung diseases. Additional insight into the relationship between disease-associated mechanisms and local effects of 1,25(OH)₂D is expected to contribute to the design of future strategies aimed at improving local levels of 1,25(OH)₂D and signaling in chronic inflammatory lung diseases.