Associations Between Prenatal Vitamin D and Placental Gene Expression

BACKGROUND

Vitamin D is a hormone that regulates gene transcription. Prenatal vitamin D has been linked to immune and vascular function in the placenta, a key organ of pregnancy. Transcriptome-wide RNA sequencing can provide a more complete representation of the placental effects of vitamin D.

OBJECTIVES

We investigated the association between prenatal vitamin D concentrations and placental gene expression in a large, prospective pregnancy cohort.

METHODS

Participants were recruited from Shelby County, TN, United States, in the Conditions Affecting Neurocognitive Development and Learning in Early childhood (CANDLE) study. Vitamin D (plasma total 25-hydroxyvitatmin D, [25(OH)D]) was measured at midpregnancy (16-28 wk) and delivery. RNA was sequenced from placental samples collected at birth. We identified differentially expressed genes (DEGs) using adjusted linear regression models. We also conducted weighted gene coexpression network analysis.

RESULTS

The median 25(OH)D of participants was 21.8 ng/mL at midpregnancy (N = 774; IQR: 15.4-26.5 ng/mL) and 23.6 ng/mL at delivery (n = 753; IQR: 16.8-29.1 ng/mL). Placental expression of 17 DEGs was associated with 25(OH)D at midpregnancy, but only 1 DEG was associated with 25(OH)D at delivery. DEGs were related to energy metabolism, cytoskeletal function, and transcriptional regulation. We identified 2 weighted gene coexpression network analysis gene modules whose expression was associated with 25(OH)D at midpregnancy and 1 module associated with 25(OH)D at delivery. These modules were enriched for genes related to mitochondrial and cytoskeletal function and were regulated by transcription factors including ARNT2 and FOSL2. We also identified 12 modules associated with 25(OH)D in females and 1 module in males.

CONCLUSIONS

25(OH)D during midpregnancy, but not at delivery, is associated with placental gene expression at birth. Future research is needed to investigate a potential role of vitamin D in modulating placental mitochondrial metabolism, intracellular transport, and transcriptional regulation during pregnancy.

Association of serum vitamin D with diagnosis and growth of abdominal aortic aneurysm

Objective

We examined the associations between 25-hydroxy vitamin D (25(OH)D3) concentration and the diagnosis and growth of abdominal aortic aneurysm (AAA).

Methods

AAA cases and healthy controls were recruited from vascular centers or the community. A subset of participants with AAA were monitored by repeat ultrasound examination to assess AAA growth. Serum 25(OH)D3 concentration was measured using a validated mass spectrometry method and categorized into guideline-recommended cut-points after deseasonalization. The associations between deseasonalized 25(OH)D3 concentration and AAA diagnosis and growth were examined using logistic regression and linear mixed effects modeling.

Results

A total of 4673 participants consisting of 873 (455 controls and 418 cases) from Queensland and 3800 (3588 controls and 212 cases) from Western Australia were recruited. For every 1 standard deviation increase in 25(OH)D3 concentration, odds of AAA diagnosis was significantly reduced in both Queensland (adjusted odds ratio: 0.81; 95% confidence interval [CI]: 0.69-0.95; P = .009) and Western Australia (adjusted odds ratio: 0.80; 95% CI: 0.68-0.94; P = .005) cohorts. A subset of 310 eligible participants with small AAA from both regions were followed for a median of 4.2 (interquartile range: 2.0-5.8) years. Compared with vitamin D sufficient participants (50 to ˂75 nmol/L), annual mean AAA growth was significantly greater in those with higher vitamin D (≥75 nmol/L) (adjusted mean difference: 0.1 mm/y, 95% CI: 0.1-0.2; P < .001).

Conclusions

High 25(OH)D3 concentration was paradoxically associated with a lower likelihood of AAA diagnosis and faster AAA growth. Further research is needed to resolve these conflicting findings.

Hyperparathyroidism and Peripheral Arterial Disease

Primary hyperparathyroidism (PHPT) is presented in various forms, including classic PHPT, characterised by increased parathyroid hormone (PTH) secretion, normohormonal PHPT, and normocalcaemic PHPT. Secondary hyperparathyroidism is characterised by increased PTH secretion triggered by factors such as vitamin D deficiency and kidney failure. This review aims to discuss the involvement of hyperparathyroidism (HPT) in atherosclerosis, including peripheral arterial disease (PAD). The increased level of PTH is involved in developing subclinical and overt vascular diseases, encompassing endothelial dysfunction, vascular stiffness, hypertension, and coronary and peripheral arterial diseases. It has been consistently associated with an augmented risk of cardiovascular morbidity and mortality, independent of classical risk factors for atherosclerosis. Chronic hypercalcemia associated with increased levels of PTH contributes to the development of calcification of vessel walls and atherosclerotic plaques. Vascular calcification can occur in the intima or media of the arterial wall and is associated with stiffness of peripheral arteries, which the formation of atherosclerotic plaques and narrowing of the vessel lumen can follow. For treating hyperparathyroidism, particularly SHPT, calcimimetics, novel phosphorus binders and novel vitamin D receptor activators are used. However, they are ineffective in severe PHPT. Therefore, parathyroidectomy remains the primary therapeutic option of PHPT.

Impaired intracellular calcium homeostasis enhances protein O-GlcNAcylation and promotes vascular calcification and stiffness in diabetes

Vascular calcification is accelerated in patients with diabetes mellitus and increases risk of cardiovascular events and mortality. Vascular smooth muscle cells (VSMC) play a key role in regulating vascular tone and contribute significantly to the development of diabetic vasculopathy. In this study, the function of stromal interaction molecule 1 (STIM1), an important regulator for intracellular calcium homeostasis, in diabetic vascular calcification was investigated, and the underlying molecular mechanisms were uncovered. A SMC-specific STIM1 deletion mouse model (STIM1Δ/Δ) was generated by breeding the STIM1 floxed mice (STIM1f/f) with SM22α-Cre transgenic mice. Using aortic arteries from the STIM1Δ/Δ mice and their STIM1f/f littermates, we found that SMC-specific STIM1 deletion induced calcification of aortic arteries cultured in osteogenic media ex vivo. Furthermore, STIM1 deficiency promoted osteogenic differentiation and calcification of VSMC from the STIM1Δ/Δ mice. In the low-dose streptozotocin (STZ)-induced mouse model of diabetes, SMC-specific STIM1 deletion markedly enhanced STZ-induced vascular calcification and stiffness in the STIM1Δ/Δ mice. The diabetic mice with SMC-specific STIM1 ablation also exhibited increased aortic expression of the key osteogenic transcription factor, Runx2, and protein O-GlcNAcylation, an important post-translational modulation that we have reported to promote vascular calcification and stiffness in diabetes. Consistently, elevation of O-GlcNAcylation was demonstrated in aortic arteries and VSMC from the STIM1Δ/Δ mice. Inhibition of O-GlcNAcylation with a pharmacological inhibitor abolished STIM1 deficiency-induced VSMC calcification, supporting a critical role of O-GlcNAcylation in mediating STIM1 deficiency-induced VSMC calcification. Mechanistically, we identified that STIM1 deficiency resulted in impaired calcium homeostasis, which activated calcium signaling and increased endoplasmic reticulum (ER) stress in VSMC, while inhibition of ER stress attenuated STIM1-induced elevation of protein O-GlcNAcylation. In conclusion, the study has demonstrated a causative role of SMC-expressed STIM1 in regulating vascular calcification and stiffness in diabetes. We have further identified a novel mechanisms underlying STIM1 deficiency-induced impairment of calcium homeostasis and ER stress in upregulation of protein O-GlcNAcylation in VSMC, which promotes VSMC osteogenic differentiation and calcification in diabetes.

Neuronutraceuticals Combating Neuroinflammaging: Molecular Insights and Translational Challenges—A Systematic Review

Neuropathologies, such as neuroinflammaging, have arisen as a serious concern for preserving the quality of life due to the global increase in neurodegenerative illnesses. Nowadays, neuronutraceuticals have gained remarkable attention. It is necessary to investigate the bioavailability, off-target effects, and mechanism of action of neuronutraceuticals. To comprehend the comprehensive impact on brain health, well-designed randomized controlled trials testing combinations of neuronutraceuticals are also necessary. Although there is a translational gap between basic and clinical research, the present knowledge of the molecular perspectives of neuroinflammaging and neuronutraceuticals may be able to slow down brain aging and to enhance cognitive performance. The present review also highlights the key emergent issues, such as regulatory and scientific concerns of neuronutraceuticals, including bioavailability, formulation, blood–brain permeability, safety, and efficacy.

NT-proBNP Levels Influence the Prognostic Value of Mineral Metabolism Biomarkers in Coronary Artery Disease

Background. Mineral metabolism (MM) system and N-terminal pro-brain natriuretic peptide (NT-ProBNP) have been shown to add prognostic value in patients with stable coronary artery disease (SCAD). However, the influence of NT-ProBNP on the prognostic role of MM in patients with SCAD has not been shown yet. The objective of this study is to assess the influence of NT-ProBNP on the prognostic role of MM markers in patients with SCAD. Methods: We analyzed the prognostic value of MM markers (parathormone (PTH), klotho, phosphate, calcidiol (25-hydroxyvitamin D3), and fibroblast growth factor-23) in 964 patients with SCAD and NT-ProBNP > 125 pg/mL vs. patient with NT-ProBNP ≤ 125 pg/mL included in five hospitals in Spain. The main outcome was the combination of death, heart failure, and ischemic events (any acute coronary syndrome, ischemic stroke, or transient ischemic attack). Results: A total of 622 patients had NT-proBNP > 125 pg/mL and 342 patients had NT-ProBNP ≤ 125 pg/mL. The median follow-up was 5.1 years. In the group of NT-proBNP > 125 pg/mL, the patients were older, and there were more females and smokers than in the group of patients with normal NT-proBNP. Additionally, the proportion of patients with hypertension, atrial fibrillation, ejection fraction < 40%, cerebrovascular attack, or prior coronary artery bypass graft was higher in the high NT-proBNP group. In the high NT-proBNP patients, the predictors of poor prognosis were PTH (HR = 1.06 (1.01−1.10), p < 0.001) and NT-proBNP (HR = 1.02 (1.01−1.03), p = 0.011), along with age (HR = 1.039 (1.02−1.06), p < 0.001), prior coronary artery bypass graft (HR = 1.624 (1.02−2.59), p = 0.041), treatment with statins (HR = 0.32 (0.19−0.53), p < 0.001), insulin (HR = 2.49 (1.59−4.09), p < 0.001), angiotensin receptor blockers (HR = 1.73 (1.16−2.56), p = 0.007), nitrates (HR = 1.65 (1.10−2.45), p = 0.014), and proton pump inhibitors (HR = 2.75 (1.74−4.36), p < 0.001). In the NT-proBNP ≤ 125 pg/mL subgroup, poor prognosis predictors were plasma levels of non-high-density lipoprotein (non-HDL) cholesterol (HR = 1.01 (1.00−1.02), p = 0.014) and calcidiol (HR = 0.96 (0.92−0.99), p = 0.045), as well as treatment with verapamil (HR = 11.28 (2.54−50.00), p = 0.001), and dihydropyridines (HR = 3.16 (1.63−6.13), p = 0.001). Conclusion: In patients with SCAD and NT-ProBNP > 125 pg/mL, PTH and NT-ProBNP, which are markers related to ventricular damage, are predictors of poor outcome. In the subgroup of patients with NT-ProBNP ≤ 125 pgm/L, calcidiol and non-HDL cholesterol, which are more related to vascular damage, are the independent predictors of poor outcome. Then, in patients with SCAD, baseline NT-ProBNP may influence the type of biomarker that is effective in risk prediction.

Relationship between Serum 25-Hydroxyvitamin D Level and Risk of Recurrent Stroke

Evidence for the association between vitamin D and risk of recurrent stroke remains sparse and limited. We aimed to assess the relationship between serum circulating 25-hydroxyvitamin D (25(OH)D) level and risk of recurrent stroke in patients with a stroke history, and to identify the optimal 25(OH)D level in relation to lowest recurrent stroke risk. Data from the nationwide prospective United Kingdom Biobank were used for analyses. Primary outcome was time to first stroke recurrence requiring a hospital visit during follow-up. We used Cox proportional hazards regression model with restricted cubic splines to explore 25(OH)D level in relation to recurrent stroke. The dose-response relationship between 25(OH)D and recurrent stroke risk was also estimated, taking the level of 10 nmol/L as reference. A total of 6824 participants (mean age: 60.6 years, 40.8% females) with a baseline stroke were included for analyses. There were 388 (5.7%) recurrent stroke events documented during a mean follow-up of 7.6 years. Using Cox proportional hazards regression model with restricted cubic splines, a quasi J-shaped relationship between 25(OH)D and risk of recurrent stroke was found, where the lowest recurrent stroke risk lay at the 25(OH)D level of approximate 60 nmol/L. When compared with 10 nmol/L, a 25(OH)D level of 60 nmol/L was related with a 48% reduction in the recurrent stroke risk (hazard ratio = 0.52, 95% confidence interval: 0.33-0.83). Based on data from a large-scale prospective cohort, we found a quasi J-shaped relationship between 25(OH)D and risk of recurrent stroke in patients with a stroke history. Given a lack of exploring the cause-effect relationship in this observational study, more high-quality evidence is needed to further clarify the vitamin D status in relation to recurrent stroke risk.

Joint Associations between Plasma 25-Hydroxyvitamin D, Glycemic Status, and First Stroke in General Hypertensive Adults: Results from the China Stroke Primary Prevention Trial (CSPPT)

BACKGROUND

Associations between vitamin D and stroke remain inconsistent. One major risk factor for stroke is high blood glucose, but the role it plays in this association is not well studied.

OBJECTIVES

We aimed to evaluate the individual association between plasma 25-hydroxyvitamin D [25(OH)D] and risk of first stroke stratified by fasting blood glucose (FBG), and the joint associations between plasma 25(OH)D, glycemic status, and first stroke in hypertensive adults.

METHODS

This study was a nested, case-control design utilizing data from the China Stroke Primary Prevention Trial (CSPPT). This analysis included 591 first stroke cases (of which 475 were ischemic stroke, 114 were hemorrhagic stroke, and 2 were uncertain type) and 591 matched controls. The age range of the study population was 45-75 y. The normal FBG (NFG) group had FBG <5.6 mmol/L,  and the impaired FBG (IFG) group had FBG ≥5.6 mmol/L and <7.0 mmol/L. Diabetes was defined as participants with FBG ≥7 mmol/L or who were receiving treatment with hypoglycemic agents. ORs (95% CIs) were calculated using unconditional logistic regression models.

RESULTS

Multivariable adjusted models revealed an inverse association between quartiles of 25(OH)D and risk of first stroke among participants with NFG, but the opposite trend was observed for those with IFG or diabetes. The largest ORs (>2) were observed among patients with diabetes, compared with the reference group of NFG and high 25(OH)D. Those with NFG and low 25(OH)D (OR = 1.73, 95% CI: 1.22 to 2.44) or those with IFG and high 25(OH)D (OR = 1.74, 95% CI: 1.14 to 2.67) both had a higher risk of total stroke. There was a significant interaction between 25(OH)D and a combined group of IFG and diabetes (P = 0.001). Similar results were observed for ischemic stroke.

CONCLUSIONS

In a hypertensive population, the relation between plasma 25(OH)D and risk of first stroke was significantly modified by FBG. This trial was registered at https://www.clinicaltrials.gov as NCT00794885.

Monckeberg's Medial Sclerosis as a Cause for Headache and Facial Pain

PURPOSE OF REVIEW

Mönckeberg's medial sclerosis (MMS) is a chronic, non-inflammatory degenerative condition affecting primarily the tunica media of muscular arteries resulting in their calcification. The purpose of this comprehensive review is to describe MMS as it appears in the literature, in the context of headache and facial pain. Understanding the etiopathology, the associated conditions, and the differential diagnoses is important in managing MMS.

RECENT FINDINGS

Management of MMS primarily depends upon identification of its associated conditions and their treatment. Due to the rare incidence and inadequate literature on MMS presenting with headaches, the diagnosis of the pain and the entity itself is challenging. MMS is characterized by associated systemic conditions and absence of inflammatory markers. It can mimic giant cell arteritis (GCA) and other pain entities. An interdisciplinary approach involving appropriate specialties is recommended.

Tendencies and attitudes towards dietary supplements use among undergraduate female students in Bangladesh

BACKGROUND

Dietary supplements (DS) are products that improve the overall health and well-being of individuals and reduce the risk of disease. Evidence indicates a rising prevalence of the use of these products worldwide especially among the age group 18-23 years.

AIM

The study investigates the tendencies and attitudes of Bangladeshi undergraduate female students towards dietary supplements (DS).

METHODS

A three-month (March 2018-May 2018) cross-sectional face-to-face survey was conducted in undergraduate female students in Chittagong, Bangladesh using a pre-validated dietary supplement questionnaire. The study was carried among the four private and three public university students of different disciplines in Chittagong to record their prevalent opinions and attitudes toward using DS. The results were documented and analyzed by SPSS version 22.0.

RESULTS

Ninety two percent (N = 925, 92.0%) of the respondents answered the survey questions. The prevalence of DS use was high in undergraduate female students. The respondents cited general health and well-being (n = 102, 11.0%) and physician recommendation (n = 101, 10.9%) as a reason for DS use. Majority of the students (n = 817, 88.3%) used DS cost monthly between USD 0.12 and USD 5.90. Most of the students (n = 749, 81.0%) agreed on the beneficial effect of DS and a significant portion (n = 493, 53.3%) recommended for a regular use of DS. Highly prevalent use of dietary supplements appeared in Chittagonian undergraduate female students. They were tremendously positive in using DS. The results demonstrate an increasing trend of using DS by the undergraduate females for both nutritional improvement and amelioration from diseases.

CONCLUSION

Dietary supplements prevalence was so much higher in students of private universities as compared to students of public universities. Likewise, maximal prevalence is indicated in pharmacy department compared to other departments. Students preferred brand products, had positive opinions and attitudes towards dietary supplements.

Prevalence, reasons, and determinants of dietary supplements use among undergraduate female students of health and non-health colleges in a Saudi public university

Purpose

The aim of this study was to gather data from female students studying in both health and non-health colleges at Imam Abdulrahman Bin Faisal University and report the prevalence, reasons, and determinants of dietary supplements use.

Methods

A month-long cross-sectional study was conducted in health and non-health colleges affiliated to Imam Abdulrahman Bin Faisal University in Dammam, Saudi Arabia. Convenient sampling was employed, and the data was gathered through an online survey using the English and Arabic versions of the Dietary Supplement Questionnaire (DSQ). The data was analyzed using SPSS version 23 and Medcalc. The study was approved by an ethics committee.

Results

Data from 545 participants was collected. The overall prevalence of dietary supplement use was 32.7% (95% CI: 29.06%– 36.51%). The prevalence was 29.77% (95% CI: 25.29%– 34.56%) among students at all health colleges combined and, it was 37.50% (95% CI: 31.36%– 43.96%) among students at all non-health colleges. Most students used a brand product, spent a monthly cost of SAR 286 (USD 76.3) on supplements and agreed that supplements were good for health (N = 392, 71.9%). Students from non-health- colleges agreed that dietary supplements are good for health in greater numbers as compared to non-health college students (p < 0.001). Students aged ≥ 20 years, studying in a non-health college and up to 3^rd year of study, were more 2 times more likely to agree that dietary supplements are good for health.

Conclusion

Supplements were commonly used among female students at this university however, it was quite low as compared to students from other local and regional universities. Prevalence was higher in non-health colleges as compared to health colleges and the most commonly used supplements were brand products and, multivitamins, used for general health and well-being. This highlights the inclination of students towards supplement use.

Epidemiological Research Advances in Vascular Calcification in Diabetes

Vascular calcification is the transformation of arterial wall mesenchymal cells, particularly smooth muscle cells (SMCs), into osteoblast phenotypes by various pathological factors. Additionally, vascular transformation mediates the abnormal deposition of calcium salts in the vascular wall, such as intimal and media calcification. Various pathological types have been described, such as calcification and valve calcification. The incidence of vascular calcification in patients with diabetes is much higher than that in nondiabetic patients, representing a critical cause of cardiovascular events in patients with diabetes. Because basic research on the clinical transformation of vascular calcification has yet to be conducted, this study systematically expounds on the risk factors for vascular calcification, vascular bed differences, sex differences, ethnic differences, diagnosis, severity assessments, and treatments to facilitate the identification of a new entry point for basic research and subsequent clinical transformation regarding vascular calcification and corresponding clinical evaluation strategies.

Sirtuin-1 and Its Relevance in Vascular Calcification

Vascular calcification (VC) is highly associated with cardiovascular disease and all-cause mortality in patients with chronic kidney disease. Dysregulation of endothelial cells and vascular smooth muscle cells (VSMCs) is related to VC. Sirtuin-1 (Sirt1) deacetylase encompasses a broad range of transcription factors that are linked to an extended lifespan. Sirt1 enhances endothelial NO synthase and upregulates FoxOs to activate its antioxidant properties and delay cell senescence. Sirt1 reverses osteogenic phenotypic transdifferentiation by influencing RUNX2 expression in VSMCs. Low Sirt1 hardly prevents acetylation by p300 and phosphorylation of β-catenin that, following the facilitation of β-catenin translocation, drives osteogenic phenotypic transdifferentiation. Hyperphosphatemia induces VC by osteogenic conversion, apoptosis, and senescence of VSMCs through the Pit-1 cotransporter, which can be retarded by the sirt1 activator resveratrol. Proinflammatory adipocytokines released from dysfunctional perivascular adipose tissue (PVAT) mediate medial calcification and arterial stiffness. Sirt1 ameliorates release of PVAT adipokines and increases adiponectin secretion, which interact with FoxO 1 against oxidative stress and inflammatory arterial insult. Conclusively, Sirt1 decelerates VC by means of influencing endothelial NO bioavailability, senescence of ECs and VSMCs, osteogenic phenotypic transdifferentiation, apoptosis of VSMCs, ECM deposition, and the inflammatory response of PVAT. Factors that aggravate VC include vitamin D deficiency-related macrophage recruitment and further inflammation responses. Supplementation with vitamin D to adequate levels is beneficial in improving PVAT macrophage infiltration and local inflammation, which further prevents VC.

25-Hydroxyvitamin D level, vitamin D intake, and risk of stroke: A dose-response meta-analysis

BACKGROUND & AIMS

A growing number of studies have shown that vitamin D are related to the risk of stroke, however, the dose-response association between vitamin D and the risk of stroke is still unclear. Accordingly, we conducted a dose-response meta-analysis to evaluate the relationships between 25-hydroxyvitamin D [25(OH)D] level, vitamin D intake, and the risk of stroke by summarizing cohort studies.

METHODS

PubMed, Embase, Cochrane and the Web of Science database were searched for related studies. Cohort studies examining the influence of 25(OH)D level and vitamin D intake on stroke risk were summarized. Dose-response relationships were determined using a random-effect model.

RESULTS

Twenty cohort studies involving 217,235 participants were included. The pooled relative risk for the high-versus-low categories was 0.74 (95% CI: 0.66-0.83) for 25(OH)D level, and 0.75 (95% CI: 0.57-0.98) for vitamin D intake. In addition, there were non-linear relationships between 25(OH)D level, vitamin D intake, and stroke risk. The incidence of stroke was reduced to its lowest point, with a reduction of about 20%, when 25(OH)D level was about 50 nmol/L or vitamin D intake was about 12 μg/day.

CONCLUSION

25(OH)D level and vitamin D intake were both inversely related to stroke risk, with a non-linear dose-response relationship.

The Association between Cardiovascular Disease Risk Factors and 25-Hydroxivitamin D and Related Analytes among Hispanic/Latino Adults: A Pilot Study

Although the association of vitamin D levels with cardiovascular risk profiles among Hispanics/Latinos has been studied, little is known about this association among Hispanics/Latinos with chronic conditions. This pilot study determined serum vitamin D and parathyroid hormone (PTH) levels in a sample of participants from the University of Illinois at the Chicago Cohort of Patients, Family and Friends (UIC Cohort) and examined their association with traditional cardiovascular disease risk factors. From July 2012 to June 2016, the UIC Cohort study enrolled and conducted clinical examinations on men and women ages 18 years and older, who had one or more diagnosed chronic diseases/conditions (excluding cancer). This pilot study sample included 40 participants from the six main Hispanic/Latino background groups in the United States, namely Dominican, Cuban, Puerto Rican, Mexican, Central American, and South American, and were grouped by Caribbean or mainland origin. No substantial differences were noted in the vitamin D-related measures by Hispanic/Latino background, but the PTH levels were somewhat higher in the Caribbean vs. mainland group (43.0 ± 4.6 vs. 38.6 ± 2.7 pg/mL). The associations between selected CVD risk factors (systolic and diastolic blood pressure (SBP, DBP), total cholesterol, glucose) and PTH and vitamin D-related analytes were investigated using interval-censored multivariate regression models adjusted for age, sex, percent body fat, serum albumin/calcium, and Hispanic/Latino background. A negative association between total 25[OH]D and blood pressure was corroborated (SBP: β = -1.2, 95%CI = -2.0, -0.3; DBP: β = -0.7, 95% CI = -1.2, -0.1), whereas a positive association with total cholesterol was observed (β = 1.9, 95% CI = 0.02, 3.7). Levels of 1, 25[OH]2D were not associated with CVD risk factors, whereas 24, 25[OH]2D3 was associated with blood pressure (SBP: β = -13.0, 95% CI = -20.7, -5.2; DBP: β = -6.3, 95% CI = -11.6, -1.0). Estimated free 25[OH]D was inversely associated with both SBP (β = -3.5, 95% CI = -6.1, -0.9) and DBP (β = -2.1, 95% CI = -3.8, -0.3). Similarly, calculated bioavailable 25[OH]D was inversely associated with both SBP (β = -9.2, 95% CI = -15.9, -2.4) and DBP(β = -5.3, 95% CI = -9.8, -0.8). In conclusion, a negative association between 25[OH]D with BP was observed and a positive association with lipids is suggested. Due to the small sample size, most associations did not reach statistical significance.

Questioning the Safety of Calcidiol in Hemodialysis Patients

Background. Epidemiological studies have suggested a survival benefit for hemodialysis patients on paricalcitol or calcitriol, but nutritional vitamin D supplementation of patients already on vitamin D receptor (VDR) activators is controversial. Methods. This observational retrospective cohort study was conducted with prospectively collected data from all consecutive patients with chronic kidney disease (CKD) who underwent hemodialysis under routine clinical practice conditions for two years. Results. Of the 129 patients, 89 were treated with calcidiol, paricalcitol, and/or calcitriol. The patients with any vitamin D formulation had higher serum concentrations of 25-hydroxy vitamin D and fibroblast growth factor-23 and tended to have higher mortality rates (42% vs. 25%, p = 0.07). On subgroup analysis, any calcidiol treatment or calcidiol combined with paricalcitol associated with significantly higher mortality rates than no treatment (47% and 62.5%, p = 0.043 and 0.008, respectively). The association between calcidiol/paricalcitol treatment and elevated mortality remained significant after adjusting for age, sex, diabetes, C-reactive protein, and hemodialysis vintage. Any calcidiol and calcidiol/paricalcitol treatment exhibited a dose-response relationship with mortality (p for trend: 0.002 and 0.005, respectively). Conclusions. These data draw attention to the hitherto unexplored safety of calcidiol supplementation in patients on hemodialysis, especially in those already on vitamin D. Until clinical trials demonstrate the safety and efficacy of this approach, caution should be exercised when prescribing these patients ≥0.5 calcidiol mg/month.

Dietary supplement use among undergraduate male students in health and non-health cluster colleges of a public-sector university in Dammam, Saudi Arabia

BACKGROUND

Dietary supplements (DS) are nutraceuticals that improve overall health and well-being of an individual as well as reduce the risk of diseases. Evidence indicates a rising prevalence of these products worldwide especially among college students. Studies have reported an increasing use of supplements among Saudi students. However, the scope of those researches was limited to prevalence data. Hence, the aim of our study was to document the prevalence, opinions, attitudes, reasons for use and monthly cost attributed to dietary supplement use.

METHODS

A 3-month cross-sectional study was conducted to evaluate use of dietary supplement among health and non-health college students at a public-sector university in Dammam city, Saudi Arabia. It was conducted using Arabic version of the Dietary supplement questionnaire (DSQ-A). A total of 469 male students responded to the survey giving a response rate of 93.8%. The students were from ten colleges of the university. The data was analyzed by SPSS version 22. The study was approved by Institutional Review Board of Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia (IRB-UGS-2018-05-074).

RESULTS

The overall prevalence of dietary supplement use in the university was 29.42%. In health cluster colleges, it was reported at 35.91% while in non-health cluster college it was 23.69%. Maintaining general health and well-being was the most common reason for use. Prevalence of multivitamins and whey proteins was approximately 23%. Average monthly cost of supplement was SAR 278.92 (USD 74.39). Cost was positively correlated (ρ = 0.305) with satisfaction score. Students preferred brand products (16.4%). 41.4% students opined that DS may prevent chronic illness if used regularly and agreed that they are good for health. Majority of students (65%) recommended DS use only upon physician's recommendation. College clusters and study-year was associated (p-value< 0.01) with students' opinion. Students in health cluster colleges were more likely to recommend supplements (OR 3.715, p-value< 0.0001).

CONCLUSION

Prevalence of dietary supplement use was lower than other local and international university students. Health cluster colleges had higher prevalence as compared to non-health cluster colleges. Multivitamins and whey protein were the most commonly used types of DS. Students preferred brand products, had positive opinions and attitudes towards dietary supplement. However, they recommended supplements use to others only upon a physician's recommendation.

Vitamin D in Vascular Calcification: A Double-Edged Sword?

Vascular calcification (VC) as a manifestation of perturbed mineral balance, is associated with aging, diabetes and kidney dysfunction, as well as poorer patient outcomes. Due to the current limited understanding of the pathophysiology of vascular calcification, the development of effective preventative and therapeutic strategies remains a significant clinical challenge. Recent evidence suggests that traditional risk factors for cardiovascular disease, such as left ventricular hypertrophy and dyslipidaemia, fail to account for clinical observations of vascular calcification. Therefore, more complex underlying processes involving physiochemical changes to mineral balance, vascular remodelling and perturbed hormonal responses such as parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF-23) are likely to contribute to VC. In particular, VC resulting from modifications to calcium, phosphate and vitamin D homeostasis has been recently elucidated. Notably, deregulation of vitamin D metabolism, dietary calcium intake and renal mineral handling are associated with imbalances in systemic calcium and phosphate levels and endothelial cell dysfunction, which can modulate both bone and soft tissue calcification. This review addresses the current understanding of VC pathophysiology, with a focus on the pathogenic role of vitamin D that has provided new insights into the mechanisms of VC.

Evaluation of serum 25-hydroxyvitamin D levels in calcific rheumatic mitral stenosis- A cross sectional study

Background and aim of the study

Rheumatic mitral stenosis (RMS) is an autoimmune, progressive destructive valve disease occurring as a sequele of streptococcal infection. Epidemiological studies support an association of vitamin D deficiency with initial susceptibility and severity of autoimmune diseases. The aim of the present study was to assess serum level of 25 hydroxyvitamin D in subjects of RMS and assess if any correlation exists with serum levels of vitamin D and severity of disease along with calcification assessed semi-quantitatively by echocardiography by applying Wilkins score.

Method

Fifty five patients of RMS without any calcification of the valves (Group A) assessed by echocardiography along with fifty five patients of RMS with mild to moderately calcified valves (Group B, Wilkins calcium score 1 or 2) and 55 patients with severely calcified valves (Group C, Wilkins calcium score 3 or 4) were enrolled for the study. All subjects underwent clinical, echocardiographic, and biochemical evaluation. The total Wilkins score, Wilkins calcium score along with serum level of 25 hydroxyvitamin D was evaluated in all the patients.

Results

The median serum level of 25 hydroxyvitamin D was significantly lower in Group B (20.4 ng/ml, p < 0.001) and group C (11.4 ng/ml, p < 0.001) compared to Group A patients (27.9 ng/ml). Similarly serum level of 25 hydroxyvitamin D in Group C patients were significantly less than Group B patients (p < 0.001). A significant inverse correlation was identified between serum level of 25 hydroxyvitamin D and total Wilkins score (r = −0.65, p < 0.001) as well as Wilkins calcium score (r = −0.69, p < 0.001). But no correlation was identified between 25 hydroxyvitamin D levels and other echocardiographic parameters of RMS.

Conclusion

Our study showed a significantly lower level of 25 hydroxyvitamin D in subjects of RMS with severely damaged and calcified valves as compared to those with less severely damaged non-calcified valves and it correlated with both Wilkins score and Wilkins calcification score. Thus a link may exist between vitamin D deficiency (an immunomodulator) and severity of autoimmune injury on the valves.

Dietary Supplements: Regulatory Challenges and Research Resources

Many of the scientific and regulatory challenges that exist in research on the safety, quality and efficacy of dietary supplements are common to all countries as the marketplace for them becomes increasingly global. This article summarizes some of the challenges in supplement science and provides a case study of research at the Office of Dietary Supplements at the National Institutes of Health, USA, along with some resources it has developed that are available to all scientists. It includes examples of some of the regulatory challenges faced and some resources for those who wish to learn more about them.

Vitamin D, a modulator of musculoskeletal health in chronic kidney disease

The spectrum of activity of vitamin D goes beyond calcium and bone homeostasis, and growing evidence suggests that vitamin D contributes to maintain musculoskeletal health in healthy subjects as well as in patients with chronic kidney disease (CKD), who display the combination of bone metabolism disorder, muscle wasting, and weakness. Here, we review how vitamin D represents a pathway in which bone and muscle may interact. In vitro studies have confirmed that the vitamin D receptor is present on muscle, describing the mechanisms whereby vitamin D directly affects skeletal muscle. These include genomic and non-genomic (rapid) effects, regulating cellular differentiation and proliferation. Observational studies have shown that circulating 25-hydroxyvitamin D levels correlate with the clinical symptoms and muscle morphological changes observed in CKD patients. Vitamin D deficiency has been linked to low bone formation rate and bone mineral density, with an increased risk of skeletal fractures. The impact of low vitamin D status on skeletal muscle may also affect muscle metabolic pathways, including its sensitivity to insulin. Although some interventional studies have shown that vitamin D may improve physical performance and protect against the development of histological and radiological signs of hyperparathyroidism, evidence is still insufficient to draw definitive conclusions.

High phosphate induces a pro-inflammatory response by vascular smooth muscle cells and modulation by vitamin D derivatives

In chronic kidney disease patients, high phosphate (HP) levels are associated with cardiovascular disease, the major cause of morbidity and mortality. Since serum phosphate has been independently correlated with inflammation, the present study aimed to investigate an independent direct effect of HP as a pro-inflammatory factor in VSMCs. A possible modulatory effect of vitamin D (VitD) was also investigated. The study was performed in an in vitro model of human aortic smooth muscle cells (HASMCs). Incubation of cells in an HP (3.3 mM) medium caused an increased expression of the pro-inflammatory mediators intercellular adhesion molecule 1 (ICAM-1), interleukins (ILs) IL-1β, IL-6, IL-8 and tumour necrosis factor α (TNF-α) (not corroborated at the protein levels for ICAM-1), as well as an increase in reactive oxygen/nitrogen species (ROS/RNS) production. This was accompanied by the activation of nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) signalling as demonstrated by the increase in the nuclear translocation of nuclear factor κ-light-chain-enhancer of activated B cells protein 65 (p65-NF-κΒ) assessed by Western blotting and confocal microscopy. Since all these events were attenuated by an antioxidant pre-incubation with the radical scavenger Mn(III)tetrakis (4-benzoic acid) porphyrin (MnTBAP), it is suggested that the inflammatory response is upstream mediated by the ROS/RNS-induced activation of NF-κΒ. Addition of paricalcitol (PC) 3·10−8 M to cells in HP prevented the phosphate induced ROS/RNS increase, the activation of NF-κΒ and the cytokine up-regulation. A bimodal effect was observed, however, for different calcitriol (CTR) concentrations, 10−10 and 10−12 M attenuated but 10−8 M stimulated this phosphate induced pro-oxidative and pro-inflammatory response. Therefore, these findings provide novel mechanisms whereby HP may directly favour vascular dysfunctions and new insights into the protective effects exerted by VitD derivatives.

Vitamin-D concentrations, cardiovascular risk and events - a review of epidemiological evidence

Vitamin D has long been established as an elemental factor of bone physiology. Beyond mineral metabolism, the expression of the vitamin D receptor has been identified throughout the cardiovascular (CV) system. Experimental studies showed beneficial effects of vitamin D on heart and vessels, but vitamin D intoxication in animals also led to hypercalcemia and vascular calcification. Our knowledge has been extended by epidemiological studies that showed that 25-hydroxyvitamin D (25(OH)D) levels are inversely associated with an increased CV risk itself, but also with established CV risk factors, such as arterial hypertension, endothelial dysfunction and atherosclerosis. Conversely, randomized controlled trials could not document significant and consistent effects of vitamin D supplementation on CV risk or events. Potential explanations may lie in differences in reference ranges or the possibility that low vitamin D in CV disease is only an epiphenomenon. In the latter case, the key question is why low 25(OH)D levels are such a strong predictor of health. While we wait for new data, the current conclusion is that vitamin D is a strong risk marker for CV risk factors and for CV diseases itself.

Effects of low calcium dialysate on the progression of coronary artery calcification in hemodialysis patients: An open-label 12-month randomized clinical trial

BACKGROUND

The association between the dialysate calcium level and coronary artery calcification (CAC) has not yet been evaluated in hemodialysis patients. The objective of this study was to determine whether lowering the dialysate calcium levels would decrease the progression of coronary artery calcification (CAC) compared to using standard calcium dialysate.

METHODS

We conducted an open-label randomized trial with parallel groups. The patients were randomly assigned to either 12-month treatment with low calcium dialysate (LCD; 1.25mmol/L, n=36) or standard calcium dialysate (SCD; 1.5mmol/L, n=40). The primary outcome was the change in the CAC scores assessed by 64-slice multidetector computed tomography after 12months.

RESULTS

During the treatment period, CAC scores increased in both groups, especially significant in LCD group (402.5±776.8, 580.5±1011.9, P=0.004). When we defined progressors as patients at second and third tertiles of CAC changes, progressor group had a higher proportion of LCD-treated patients than SCD-treated patients (P=0.0229). In multivariate analysis, LCD treatment is a significant risk factor for increase in CAC scores (odds ratio=5.720, 95% CI: 1.219-26.843, P=0.027).

CONCLUSIONS

Use of LCD may accelerate the progression of CAC in patients with chronic hemodialysis over a 12-month period.

TRIAL REGISTRATION

Clinical Research Information Service [Internet]; Osong (Chungcheongbuk-do): Korea Centers for Disease Control and Prevention, Ministry of Health and Welfare (Republic of Korea), 2010: KCT0000942. Available from: https://cris.nih.go.kr/cris/search/search_result_st01_kren.jsp?seq=3572&sLeft=2&type=my.

Nedd4 Deficiency in Vascular Smooth Muscle Promotes Vascular Calcification by Stabilizing pSmad1

The nonosseous calcification process such as atherosclerosis is one of the major complications in several types of metabolic diseases. In a previous study, we uncovered that aberrant activity of transforming growth factor β (TGF-β) signaling pathway could contribute to the vascular smooth muscle cells' (VSMCs) calcification process. Also, we identified NEDD4 E3 ligase as a key suppressor of bone morphogenetic protein (BMP)/Smad pathway via a polyubiquitination-dependent selective degradation of C-terminal phosphorylated Smad1 (pSmad1) activated by TGF-β. Here, we further validated and confirmed the role of Nedd4 in in vivo vascular calcification progression. First, Nedd4 deletion in SM22α-positive mouse tissues (Nedd4^fl/fl ;SM22α-Cre) showed deformed aortic structures with disarranged elastin fibers at 24 weeks after birth. Second, vitamin D-induced aorta vascular calcification rate in Nedd4^fl/fl ;SM22α-Cre mice was significantly higher than their wild-type littermates. Nedd4^fl/fl ;SM22α-Cre mice showed a development of vascular calcification even at very low-level injection of vitamin D, but this was not exhibited in wild-type littermates. Third, we confirmed that TGF-β1-induced pSmad1 levels were elevated in Nedd4-deficient primary VSMCs isolated from Nedd4^fl/fl ;SM22α-Cre mice. Fourth, we further found that Nedd4^fl/fl ;SM22α-Cre mVSMCs gained mesenchymal cell properties toward osteoblast-like differentiation by a stable isotope labeling in cell culture (SILAC)-based proteomics analysis. Finally, epigenetic analysis revealed that methylation levels of human NEDD4 gene promoter were significantly increased in atherosclerosis patients. Collectively, abnormal expression or dysfunction of Nedd4 E3 ligase could be involved in vascular calcification of VSMCs by activating bone-forming signals during atherosclerosis progression. © 2016 American Society for Bone and Mineral Research.

Comparison of the effects of novel vitamin D receptor analog VS-105 and paricalcitol on chronic kidney disease-mineral bone disorder in an experimental model of chronic kidney disease

When using vitamin D, the most important clinical problems are hypercalcemia, hyperphosphatemia, and vascular calcification. VS-105 is a novel vitamin D receptor (VDR) analog. In the present study, we compared the effects of VS-105 and paricalcitol on chronic kidney disease-mineral bone disorder (CKD-MBD) in a CKD rat model. We used male Sprague-Dawley (SD) rats and performed 5/6 nephrectomy at 8-9 weeks. At 10 weeks, the rats were classified into five groups and administered vehicle, low-dose paricalcitol (LP, 0.1μg/kg), high-dose paricalcitol (HP, 0.3μg/kg), low-dose VS-105 (LV, 0.2μg/kg), and high-dose VS-105 (HV, 0.6 μg/kg) three times a week for 10 weeks. There were no significant differences in blood pressure or renal function among the five groups. Alhough serum calcium levels were comparable between the LP and LV groups, they were higher in the HP group than in the HV group. Serum phosphate levels were higher in the paricalcitol-treated groups than in the VS-105-treated groups and paticularly higher in the HP group than in the other groups. The urinary excretion of phosphate was greater in the VS-105-treated groups than in the paricalcitol-treated groups. Serum parathyroid hormone (PTH) levels decreased and serum fibroblast growth factor-23 (FGF23) levels were elevated after administering paricalcitol and VS-105; however, serum FGF23 levels were remarkably elevated in the paricalcitol-treated groups. Further biochemical analyses revealed that the calcium content of the aorta was higher in the paricalcitol-treated groups than in the VS-105-treated group. VDR and Klotho expression in the kidney was significantly higher in the VS-105-treated groups than in the paricalcitol-treated groups although both agents increased these expressions. Our data suggest that VS-105 had a lesser effect on CKD-MBD than paricalcitol except in the case of serum PTH levels. The mechanism appears to be associated with the difference in VDR and Klotho expression.

Mineral metabolism and cardiovascular disease in CKD

The mineral bone disorder of CKD, called Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD), has a major role in the etiology and progression of cardiovascular disease in CKD patients. Since the main emphasis in CKD-MBD is on three categories (bone abnormalities, laboratory abnormalities, and vascular calcifications), we have routinely accepted ectopic cardiovascular calcifications as a central risk factor in the pathophysiology of CKD-MBD for cardiac events. However, recent compelling evidence suggests that some CKD-MBD-specific factors other than vascular calcification might contribute to the onset of cardiovascular disease. Most notable is fibroblast growth factor-23 (FGF23), which is thought to be independently associated with cardiac remodeling. Slow progression of cardiac disorders, such as vascular calcification and cardiac remodeling, characterizes cardiac disease due to CKD-MBD. In contrast, fatal arrhythmia may be induced when QT prolongation occurs with CKD-MBD treatment, such as with lower Ca dialysate or the use of calcimimetics. Sudden onset of fatal cardiac events, such as heart failure and sudden cardiac death, due to fatal arrhythmia would be another distinctive phenomenon of CKD-MBD. This may be defined as CKD-MBD-specific cardiac complex syndrome.

Vascular Calcification Induced by Chronic Kidney Disease Is Mediated by an Increase of 1α-Hydroxylase Expression in Vascular Smooth Muscle Cells

Vascular calcification (VC) is a complication of chronic kidney disease that predicts morbidity and mortality. Uremic serum promotes VC, but the mechanism involved is unknown. A role for 1,25(OH)₂ D₃ in VC has been proposed, but the mechanism is unclear because both low and high levels have been shown to increase it. In this work we investigate the role of 1,25(OH)₂ D₃ produced in vascular smooth muscle cells (VSMCs) in VC. Rats with subtotal nephrectomy and kidney recipient patients showed increased arterial expression of 1α-hydroxylase in vivo. VSMCs exposed in vitro to serum obtained from uremic rats also showed increased 1α-hydroxylase expression. Those increases were parallel to an increase in VC. After 6 days with high phosphate media, VSMCs overexpressing 1α-hydroxylase show significantly higher calcium content and RUNX2 expression than control cells. 1α-hydroxylase null mice (KO) with subtotal nephrectomy and treated with calcitriol (400 ng/kg) for 2 weeks showed significantly lower levels of vascular calcium content, Alizarin red staining, and RUNX2 expression than wild-type (WT) littermates. Serum calcium, phosphorus, blood urea nitrogen (BUN), PTH, and 1,25(OH)₂ D₃ levels were similar in both calcitriol-treated groups. In vitro, WT VSMCs treated with uremic serum also showed a significant increase in 1α-hydroxylase expression and higher calcification that was not observed in KO cells. We conclude that local activation of 1α-hydroxylase in the artery mediates VC observed in uremia. © 2016 American Society for Bone and Mineral Research.

U-shaped relationship between vitamin D levels and long-term outcome in large cohort of survivors of acute myocardial infarction

BACKGROUND

Previous studies in the setting of patients with acute myocardial infarction (AMI) have demonstrated that hypovitaminosis D is associated with increased mortality risk during a follow-up whose median did not exceed two years.

OBJECTIVE

To evaluate the impact of vitamin D levels on long-term mortality in patients with AMI.

RESULTS

In our study 477 patients with AMI were included. During a median follow-up period of 57 (IQR 53-64) months, 93 patients (20%) died. A non-linear U-shaped relationship between 25(OH)D levels and long-term mortality was observed; patients with vitamin D<10ng/mL and >30ng/mL had higher mortality rate than those with intermediate values. After adjustment for differences in baseline features and treatment, it was confirmed that extreme values of vitamin D (<10 or >30ng/mL) are independent predictors of mortality with HR of 3.02 (95% CI 1.78-5.11). Other independent predictors of outcome were age, NYHA class at discharge, treatment with ACE inhibitors and statins. The estimated time-dependent ROC curve of the multivariable model including vitamin D showed an AUC significantly higher than the model without vitamin D: AUC 0.82 (95% CI 0.76-0.87) vs. 0.77 (95% CI 0.71-0.83), p=0.005. Addition of vitamin D to the model that included all significant factors for mortality improved the prognostic accuracy as showed by the metrics of reclassification (NRI 0.34 (95% CI 0.14-0.48), p=0.003 and IDI 0.06 (95% CI 0.01-0.12, p=0.005 p=0.03).

CONCLUSIONS

We report a U-shaped relationship between vitamin D levels and long-term outcome of patients surviving AMI.

Vitamin-D receptor agonist calcitriol reduces calcification in vitro through selective upregulation of SLC20A2 but not SLC20A1 or XPR1

Vitamin D deficiency (hypovitaminosis D) causes osteomalacia and poor long bone mineralization. In apparent contrast, hypovitaminosis D has been reported in patients with primary brain calcifications (“Fahr’s disease”). We evaluated the expression of two phosphate transporters which we have found to be associated with primary brain calcification (SLC20A2, whose promoter has a predicted vitamin D receptor binding site, and XPR1), and one unassociated (SLC20A1), in an in vitro model of calcification. Expression of all three genes was significantly decreased in calcifying human bone osteosarcoma (SaOs-2) cells. Further, we confirmed that vitamin D (calcitriol) reduced calcification as measured by Alizarin Red staining. Cells incubated with calcitriol under calcifying conditions specifically maintained expression of the phosphate transporter SLC20A2 at higher levels relative to controls, by RT-qPCR. Neither SLC20A1 nor XPR1 were affected by calcitriol treatment and remained suppressed. Critically, knockdown of SLC20A2 gene and protein with CRISPR technology in SaOs2 cells significantly ablated vitamin D mediated inhibition of calcification. This study elucidates the mechanistic importance of SLC20A2 in suppressing the calcification process. It also suggests that vitamin D might be used to regulate SLC20A2 gene expression, as well as reduce brain calcification which occurs in Fahr’s disease and normal aging.

Vitamin D and cardiovascular disease prevention

Vitamin D is a precursor of the steroid hormone calcitriol that is crucial for bone and mineral metabolism. Both the high prevalence of vitamin D deficiency in the general population and the identification of the vitamin D receptor in the heart and blood vessels raised interest in the potential cardiovascular effects of vitamin D. Experimental studies have demonstrated various cardiovascular protective actions of vitamin D, but vitamin D intoxication in animals is known to induce vascular calcification. In meta-analyses of epidemiological studies, vitamin D deficiency is associated with an increased cardiovascular risk. Findings from Mendelian randomization studies and randomized, controlled trials (RCTs) do not indicate significant effects of a general vitamin D supplementation on cardiovascular outcomes. Previous RCTs, however, were not adequately designed to address extraskeletal events, and did not focus on vitamin D-deficient individuals. Therefore, currently available evidence does not support cardiovascular benefits or harms of vitamin D supplementation with the commonly used doses, and whether vitamin D has cardiovascular effects in individuals with overt vitamin D deficiency remains to be evaluated. Here, we provide an update on clinical studies on vitamin D and cardiovascular risk, discuss ongoing vitamin D research, and consider the management of vitamin D deficiency from a cardiovascular health perspective.

Arteriosclerosis and vascular calcification: causes, clinical assessment and therapy

BACKGROUND

Arteriosclerosis is a pathological, structural (media vascular calcification) and physiological (modified vascular smooth vessel cells; increased arterial stiffness) alteration of the vessel wall. Through improved assessment methods (functional and imaging), it has become a well-known phenomenon in recent decades. However, its clinical importance was underestimated until recently.

MATERIALS AND METHODS

Currently available English-speaking data about conditions/diseases associated with arteriosclerosis, its clinical sequels, available diagnostic procedures and therapeutic modalities were reviewed and summarized.

RESULTS

In recent decades, emerging data have brought about a better understanding of causes and consequences of arteriosclerosis and highlight its growing clinical impact.

CONCLUSION

Although arteriosclerosis showed an independent clinical impact on cardiovascular morbidity and mortality, especially in patients with chronic kidney disease/end-stage renal disease (CKD/ESRD) and diabetes mellitus, convincing clinical therapy concepts are not available until now. The establishment of novel therapeutic strategies derived from basic research is strongly needed.

Calcitriol prevents in vitro vascular smooth muscle cell mineralization by regulating calcium-sensing receptor expression

Vascular calcification (VC) is a degenerative disease that contributes to cardiovascular morbidity and mortality. A negative relationship has been demonstrated between VC and calcium sensing receptor (CaSR) expression in the vasculature. Of interest, vitamin D response elements, which allow responsiveness to 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], are present in the promoters of the CaSR gene. We hypothesized that 1,25(OH)2D3, by modulating CaSR expression in vascular smooth muscle cells (VSMCs), might protect against VC. Human VSMCs were exposed to increasing concentrations of 1,25(OH)2D3 (0.01-10 nmol/L) in noncalcifying (1.8 mmol/L) or procalcifying Ca(2+)0 condition (5.0 mmol/L). Using quantitative RT-PCR and Western blotting we observed a significant increase in both CaSR mRNA and protein levels after exposure to 1.0 nmol/L 1,25(OH)2D3. This effect was associated with a maximal increase in CaSR expression at the cell surface after 48 hours of 1,25(OH)2D3 treatment, as assessed by flow cytometry. Down-regulation of the vitamin D receptor by small interfering RNA abolished these effects. In the procalcifying condition, 1.0 nmol/L 1,25(OH)2D3 blocked the Ca(2+)0-induced decrease in total and surface CaSR expression and protected against mineralization. Down-regulation of CaSR expression by CaSR small interfering RNA abolished this protective effect. 1,25(OH)2D3 concentrations of 0.5 and 5.0 nmol/L were also effective, but other (0.01, 0.1, and 10 nmol/L) concentrations did not modify CaSR expression and human VSMC mineralization. In conclusion, these findings suggest that nanomolar concentrations of 1,25(OH)2D3 induce a CaSR-dependent protection against VC. Both lower and higher concentrations are either ineffective or may even promote VC. Whether this also holds true in the clinical setting requires further study.

Medial vascular calcification revisited: review and perspectives

Vascular calcifications (VCs) are actively regulated biological processes associated with crystallization of hydroxyapatite in the extracellular matrix and in cells of the media (VCm) or intima (VCi) of the arterial wall. Both patterns of VC often coincide and occur in patients with type II diabetes, chronic kidney disease, and other less frequent disorders; VCs are also typical in senile degeneration. In this article, we review the current state of knowledge about the pathology, molecular biology, and nosology of VCm, expand on potential mechanisms responsible for poor prognosis, and expose some of the directions for future research in this area.

Profile of incident chronic kidney disease related-mineral bone disorders in chronic kidney disease Stage 4 and 5: A hospital based cross-sectional survey

Chronic kidney disease related-mineral bone disorder (CKD-MBD) has been poorly studied in pre-dialysis Indian CKD patients. We aimed to study the clinical, biochemical and extra skeletal manifestations of untreated CKD-MBD in pre-dialysis Stage 4 and 5 CKD patients attending nephrology out-patient clinic at a tertiary care hospital in South India. A hospital based cross-sectional survey including, demographic profile, history of CKD-MBD symptoms, measurement of serum calcium, phosphate, parathyroid hormone, 25 hydroxy vitamin D (25(OH) D) and alkaline phosphatase; lateral abdominal X-rays for abdominal aortic calcification (AAC) and echocardiography for valvular calcification (VC) was carried out. Of the 710 patients surveyed, 45% had no CKD-MBD related symptom. Prevalence of hypocalcemia, hyperphosphatemia, hyperparathyroidism (>150 pg/mL) and 25(OH) D levels <30 ng/mL was 66.3%, 59%, 89.3% and 74.7% respectively. Echocardiography was carried out in 471 patients; 96% of whom had VC (calcification score ≥1). Patients with VC were older and had lower 25(OH) D levels than those without. Lateral abdominal X-rays were obtained in 558 patients, 6.8% of whom were found to have AAC, which was associated with older age. Indian patients with incident CKD-MBD have a high prevalence of hypocalcemia, 25(OH) D deficiency and VC even prior to initiating dialysis while AAC does not appear to be common. The association between 25(OH) D deficiency and VC needs further exploration.

Fibroblast growth factor-23 and cardiac structure and function

BACKGROUND

Fibroblast growth factor-23 (FGF-23) is a phosphaturic factor previously associated with left ventricular hypertrophy and systolic dysfunction among individuals with chronic kidney disease. Whether FGF-23 acts directly to induce left ventricular hypertrophy, potentially independent of its klotho coreceptor, remains uncertain. We investigated associations of FGF-23 with cardiac structural abnormalities among individuals with a broad range of kidney function and explored potential biological mechanisms using cardiac magnetic resonance imaging and histology in klotho-null mice, an established model of constitutively elevated FGF-23.

METHODS AND RESULTS

Among 887 participants with coronary artery disease in the Heart and Soul Study, FGF-23 was modestly associated with worse left ventricular ejection fraction (-1.0% per standard deviation increase in lnFGF-23; standard error, 0.4%), but was not associated with the overall prevalence of concentric hypertrophy (odds ratio, 1.5; CI, 0.9 to 2.4) or eccentric hypertrophy (odds ratio, 1.1; CI, 0.9 to 1.3). FGF-23 was only associated with concentric hypertrophy among individuals with diminished kidney function (eGFR <60 mL/min per 1.73 m(2); odds ratio, 2.3; CI, 1.0 to 5.3; P-interaction=0.28). Comparing klotho-null with wild-type mice, null mice did not have greater left ventricular mass (P=0.37) or a lower ejection fraction (P=0.94).

CONCLUSIONS

Together, our results suggest that FGF-23 is unlikely to have major effects on cardiovascular structure and function among patients free of substantial chronic kidney disease, and these effects may not be independent of the klotho coreceptor.

Cardiovascular Risk Factors and Chronic Kidney Disease-FGF23: A Key Molecule in the Cardiovascular Disease

Patients with chronic kidney disease (CKD) are at increased risk of mortality, mainly from cardiovascular disease. Moreover, abnormal mineral and bone metabolism, the so-called CKD-mineral and bone disorder (MBD), occurs from early stages of CKD. This CKD-MBD presents a strong cardiovascular risk for CKD patients. Discovery of fibroblast growth factor 23 (FGF23) has altered our understanding of CKD-MBD and has revealed more complex cross-talk and endocrine feedback loops between the kidney, parathyroid gland, intestines, and bone. During the past decade, reports of clinical studies have described the association between FGF23 and cardiovascular risks, left ventricular hypertrophy, and vascular calcification. Recent translational reports have described the existence of FGF23-Klotho axis in the vasculature and the causative effect of FGF23 on cardiovascular disease. These findings suggest FGF23 as a promising target for novel therapeutic approaches to improve clinical outcomes of CKD patients.

Fibroblast growth factor 23 accelerates phosphate-induced vascular calcification in the absence of Klotho deficiency

Fibroblast growth factor 23 (FGF23) is a phosphate-regulating hormone that acts primarily on the kidney and parathyroid. With declining kidney function there is an increase in circulating FGF23 levels, which is associated with vascular calcification and mortality in chronic kidney disease. Whether FGF23 exerts direct effects on vasculature is unclear. We evaluated the expression of Klotho and FGF receptors in rat aortic rings and rat aorta vascular smooth muscle cells maintained in culture by reverse transcription-PCR, western blotting, and immunostaining. Signaling pathways underlying FGF23 effects were assessed by western blotting, and effects of FGF23 on osteogenic markers and phosphate transporters were assessed by real-time reverse transcription-PCR. We detected Klotho and FGFR1 in total aorta but not in vascular smooth muscle cells. FGF23 augmented phosphate-induced vascular calcification in the aortic rings from uremic rats and dose dependently increased ERK1/2 phosphorylation in Klotho-overexpressing but not naive vascular smooth muscle cells. FGF23-induced ERK1/2 phosphorylation was inhibited by SU5402 (FGFR1 inhibitor) and U0126 (MEK inhibitor). FGF23 enhanced phosphate-induced calcification in Klotho-overexpressing vascular smooth muscle cells and increased osteoblastic marker expression, which was inhibited by U0126. In contrast, phosphate transporter expression was not affected by phosphate or FGF23. Thus, FGF23 enhances phosphate-induced vascular calcification by promoting osteoblastic differentiation involving the ERK1/2 pathway.

Optimal vitamin D status: a critical analysis on the basis of evidence-based medicine

CONTEXT

Public health authorities around the world recommend widely variable supplementation strategies for adults, whereas several professional organizations, including The Endocrine Society, recommend higher supplementation.

METHODS

We analyzed published randomized controlled clinical trials to define the optimal intake or vitamin D status for bone and extraskeletal health.

CONCLUSIONS

The extraskeletal effects of vitamin D are plausible as based on preclinical data and observational studies. However, apart from the beneficial effects of 800 IU/d of vitamin D3 for reduction of falls in the elderly, causality remains yet unproven in randomized controlled trials (RCTs). The greatest risk for cancer, infections, cardiovascular and metabolic diseases is associated with 25-hydroxyvitamin D (25OHD) levels below 20 ng/mL. There is ample evidence from RCTs that calcium and bone homeostasis, estimated from serum 1,25-dihydroxyvitamin D and PTH, calcium absorption, or bone mass, can be normalized by 25OHD levels above 20 ng/mL. Moreover, vitamin D supplementation (800 IU/d) in combination with calcium can reduce fracture incidence by about 20%. Such a dose will bring serum levels of 25OHD above 20 ng/mL in nearly all postmenopausal women. Based on calculations of the metabolic clearance of 25OHD, a daily intake of 500-700 IU of vitamin D3 is sufficient to maintain serum 25OHD levels of 20 ng/mL. Therefore, the recommendations for a daily intake of 1500-2000 IU/d or serum 25OHD levels of 30 ng or higher for all adults or elderly subjects, as suggested by The Endocrine Society Task Force, are premature. Fortunately, ongoing RCTs will help to guide us to solve this important public health question.

Vitamin D receptor activation and cardiovascular disease

Vitamin D has been recently associated with several renal, cardiovascular and inflammatory diseases, beyond mineral metabolism and bone health. This is due in part to widespread expression of vitamin D receptor (VDR) on tissues and cells such as heart, kidney, immune cells, brain and muscle. In chronic kidney disease (CKD) and other chronic disorders, vitamin D deficiency [serum 25(OH)D <20 ng/mL] is very common and is associated with adverse outcomes. Paricalcitol, a selective activator of VDR, has demonstrated in several experimental and clinical studies of diabetic and non-diabetic CKD a favourable profile compared to other VDR activators, alone or as add-on to standard therapy. These beneficial effects are mediated by different actions such as reduction of oxidative stress, inflammation, downregulation of cardiac and renal renin expression, downregulation of calcifying genes and direct vascular protective effects. Furthermore, paricalcitol beneficial effects may be independent of baseline serum parathyroid hormone (PTH), calcium and phosphate levels. These benefits should be confirmed in large and well-designed ongoing clinical trials.

Restoration of bone mineralization by cinacalcet is associated with a significant reduction in calcitriol-induced vascular calcification in uremic rats

The present study investigated to what extent normalization of bone turnover goes along with a reduction of high-dose calcitriol-induced vascular calcifications in uremic rats. Five groups of male Sprague-Dawley rats were studied: sham-operated controls (n = 7), subtotally nephrectomized (SNX) uremic (CRF) animals (n = 12), CRF + calcitriol (vitD) (0.25 μg/kg/day) (n = 12), CRF + vitD + cinacalcet (CIN) (10 mg/kg/day) (n = 12), and CRF + vitD + parathyroidectomy (PTX) (n = 12). Treatment started 2 weeks after SNX and continued for the next 14 weeks. High-dose calcitriol treatment in hyperparathyroid rats went along with the development of distinct vascular calcification, which was significantly reduced by >50 %, in both CIN-treated and PTX animals. Compared to control animals and those of the CRF group, calcitriol treatment either in combination with CIN or PTX or not was associated with a significant increase in bone area comprising ±50 % of the total tissue area. However, whereas excessive woven bone accompanied by a dramatically increased osteoid width/area was seen in the CRF + vitD group, CIN treatment and PTX resulted in significantly reduced serum PTH level, which was accompanied by a distinct reduction of both the bone formation rate and the amount of osteoid. These data indicate that less efficient calcium and phosphorus incorporation in bone inherent to the severe hyperparathyroidism in vitamin D-treated uremic rats goes along with excessive vascular calcification, a process which is partially reversed by CIN treatment in combination with a more efficacious bone mineralization, thus restricting the availability of calcium and phosphate for being deposited in the vessel wall.

A preliminary study of the potential role of FGF-23 in coronary calcification in patients with suspected coronary artery disease

OBJECTIVE

The association of fibroblast growth factor 23 (FGF-23) with vascular disease in patients with preserved renal function is not well understood. The purpose of this study was to investigate the relationship of serum FGF-23 with coronary calcification in patients without chronic kidney disease and diabetes mellitus (DM).

METHODS

A cross-sectional study was performed in 148 consecutive patients with suspected coronary artery disease who underwent 64-slice computed tomography coronary angiography for diagnosis of coronary artery disease. Patients with eGFR <60 mL/min/1.73 m(2), proteinuria, or DM were excluded. Associations of coronary calcification (evaluated by Agatston score) were examined with classical risk factors and with inflammatory markers, adipocytokines and FGF-23.

RESULTS

The median creatinine, eGFR and FGF-23 levels were 0.7 mg/dL, 74.6 mL/min/1.73 m(2), and 26 pg/mL respectively. The strongest association was found between age and Agatston score (r = 0.367, p < 0.001) in univariate logistic regression analysis. No atherogenic risk factors, including inflammatory markers and adipocytokine levels, were associated with Agatston score. Among calcium/phosphate metabolism markers, FGF-23 showed a weak but significant correlation with Agatston score (r = 0.169, p = 0.039). In multivariate linear regression analysis, age and FGF-23 (r = 0.188, p = 0.016) were independently associated with the Agatston score.

CONCLUSION

Serum FGF-23 levels were associated with coronary calcification independently of classical risk factors and of adipocytokines and inflammatory markers in patients with preserved renal function. FGF-23 may also have a direct effect on progression of coronary calcification and further studies are required to examine this issue.