Endothelial stress induces the release of vitamin D-binding protein, a novel growth factor

Vitamin D and vitamin D binding protein levels in COVID-19 intensive care unit patients: A prospective multicenter study

Background

Vitamin D binding protein plays a crucial role in regulating vitamin D levels by carrying vitamin D and its metabolites and immunological response by binding to endotoxins and fatty acids. We aimed to compare vitamin D, DBP, and specific inflammatory markers among intensive care unit (ICU) patients with and without the COVID19 virus.

Methods

This multicenter study in two training and research hospitals included 37 (13 female) COVID-19positive and 51 (34 female) COVID-19-negative ICU patients. 25(OH) vitamin D, DBP, C-reactive protein (CRP), procalcitonin (PCT), D-dimer, troponin T (TnT), interleukin 6 (IL-6) and ferritin levels, survival, mortality rates, duration of stay (ICU) were examined.

Results

We observed higher ferritin and CRP levels, along with lower DBP, TnT, and D-dimer levels, in patients with COVID-19. ICU patients with COVID-19 exhibited elevated mortality rates (Odds Ratio: 3.012, 95% Confidence Interval (1.252-7.248), p=0.013). However, no statistically significant correlation was observed between mortality rates and Vitamin D or DBP levels across the ICU patient cohort.

Conclusions

Vitamin D values were found to be low in all intensive care patients, regardless of their COVID-19 status. Contrary to the literature, COVID-19 patients had lower D-dimer and TNT levels than negative controls. However, COVID-19-positive ICU patients have decreased DBP. Further, DBP gene polymorphism studies are needed to explain this situation.

Vitamin D: A Bridge between Kidney and Heart

Chronic kidney disease (CKD) and cardiovascular disease (CVD) are highly prevalent conditions, each significantly contributing to the global burden of morbidity and mortality. CVD and CKD share a great number of common risk factors, such as hypertension, diabetes, obesity, and smoking, among others. Their relationship extends beyond these factors, encompassing intricate interplay between the two systems. Within this complex network of pathophysiological processes, vitamin D has emerged as a potential linchpin, exerting influence over diverse physiological pathways implicated in both CKD and CVD. In recent years, scientific exploration has unveiled a close connection between these two prevalent conditions and vitamin D, a crucial hormone traditionally recognized for its role in bone health. This article aims to provide an extensive review of vitamin D's multifaceted and expanding actions concerning its involvement in CKD and CVD.

Role of Vitamin D in Management of Diabetes and Unresolved Cardiovascular Diseases

BACKGROUND

Vitamin D deficiency is becoming a widely recognized global health issue. Serum values of 25-(OH) vitamin D (<20 ng/ml) are used to identify vitamin D deficiency. By prompting vascular endothelial cells to activate their nuclear receptor in cardio-myocytes, Vitamin D regulates obesity, Renin-angiotensin system (RAS), energy consumption, and pancreatic cell function. Vitamin D deficiency has been associated with diabetes, asthma, hyperlipidaemia, and pulmonary hypertension in humans.

METHODS

PubMed and Google Scholar databases were utilised to search the literature on vitamin D and related diseases.

RESULT

It is also linked to an elevated risk of death and heart disease. On the other hand, metaanalyses of vitamin D intervention and trials have found no substantial changes in insulin sensitivity, lipid markers, or blood pressure, which result in the association between deficiency of vitamin D and cardiovascular disease.

CONCLUSION

In this review, we present the most recent research on the effects of Vitamin D therapy on various cardiovascular diseases and diabetes, and explain the underlying mechanisms.

Proteomic Approaches and Potential Applications in Autosomal Dominant Polycystic Kidney Disease and Fabry Disease

Although rare, hereditary diseases, such as autosomal dominant polycystic kidney disease (ADPKD) and Fabry disease (FD) may significantly progress towards severe nephropathy. It is crucial to characterize it accurately, predict the course of the illness and estimate treatment effectiveness. A huge effort has been undertaken to find reliable biomarkers that might be useful for an early prevention of the disease progression and/or any invasive diagnostic procedures. The study of proteomics, or the small peptide composition of a sample, is a field of study under continuous development. Over the past years, several strategies have been created to study and define the proteome of samples from widely varying origins. However, urinary proteomics has become essential for discovering novel biomarkers in kidney disease. Here, the extracellular vesicles in human urine that contain cell-specific marker proteins from every segment of the nephron, offer a source of potentially valuable urinary biomarkers, and may play an essential role in kidney development and kidney disease. This review summarizes the relevant literature investigating the proteomic approaches and potential applications in the regular studies of ADPKD and FD.

The Influence of Dietary Interventions on Arterial Stiffness in Overweight and Obese Subjects

Arterial stiffness is often increased in overweight/obese subjects before the development of hypertension. It is also one of the earliest indicators of increased cardiovascular disease risk and can be considered a good predictor of the development of subclinical cardiovascular dysfunction. Arterial stiffness is a significant prognostic factor influencing cardiovascular risk, which dietary habits can modify. Obese patients should use the caloric-restricted diet because it augments aortic distensibility, diminishes pulse wave velocity (PWV), and increases the activity of endothelial nitric oxide synthases. High intake of saturated fatty acids (SFA), trans fats, and cholesterol, typical for the Western diet, impairs endothelial function and raises brachial-ankle PMV. The replacement of SFA with monounsaturated (MUFA) or polyunsaturated fatty acids (PUFA) derived from seafood and plants diminishes the risk of arterial stiffness. The dairy product intake (excluding butter) decreases PWV in the general population. The high-sucrose diet causes toxic hyperglycemia and increases arterial stiffness. Complex carbohydrates with a low glycemic index (including isomaltose) should be recommended to keep vascular health. The high sodium intake (>10 g/day), particularly associated with low potassium consumption, has a deleterious effect on arterial stiffness (↑ baPWV). Since vegetables and fruits are good sources of vitamins and phytochemicals, they should be recommended in patients with high PMV. Thus, the dietary recommendation to prevent arterial stiffness should be similar to the Mediterranean diet, which is rich in dairy products, plant oils, and fish, with a minimal red meat intake and five servings of fruits and vegetables daily.

Evaluating the Arterial Stiffness as a Useful Tool in the Management of Obese Children

Childhood obesity speeds up the development of arterial stiffness and progressively increases the values of arterial pressure. The purpose of this study is to investigate the value of using pulse wave analysis (PWA) to measure arterial stiffness as a sign of vascular wall impairment in obese children. The research was focused on 60 subjects: 33 obese and 27 normal-weight. Ages ranged from 6 to 18 years old. PWA includes parameters such as pulse wave velocity (PWV), augmentation index (AIx), peripheral and central blood pressure (SBP, DBP, cSBP, cDBP), heart rate, and central pulse pressure (cPP). The device used was a Mobil-O-Graph. Blood parameters were taken from the subject's medical history, not older than 6 months. A high BMI and a large waist circumference are linked to a high PWV. The levels of LDL-c, triglycerides (TG), non-HDL-c, TG/HDL-c ratio, and total cholesterol-HDL-c ratio significantly correlate to PWV, SBP, and cSBP. Alanine aminotransferase is a reliable predictor of PWV, AIx, SBP, DBP, and cDBP, while aspartate aminotransferase is a significant predictor of AIx, mean arterial pressure (MAP), cSBP, and cPP. 25-OH-Vitamin D negatively correlates with PWV, SBP, and MAP and significantly predicts the MAP. Cortisol and TSH levels are not significant to arterial stiffness in obese children without specific comorbidities and neither is fasting glucose in obese children without impaired glucose tolerance. We conclude that PWA contributes valuable data regarding patients' vascular health and should be considered a reliable tool in the management of obese children.

The Comparative Effects of Different Types of Oral Vitamin Supplements on Arterial Stiffness: A Network Meta-Analysis

Arterial stiffness, a significant prognostic factor of cardiovascular disease, may be affected by dietary factors. Research on the effects of oral vitamin supplements on arterial stiffness and/or endothelial function has produced controversial results. Therefore, the aim of this network meta-analysis was to comparatively assess the effect of different types of oral vitamin supplements on arterial stiffness in the adult population. We searched the PubMed, Embase, Cochrane Library, and Web of Science databases for randomized controlled trials from their inception to 30 September 2021. A network meta-analysis using a frequentist perspective was conducted to assess the effects of different types of oral vitamin supplements on arterial stiffness, as determined by pulse wave velocity. In total, 22 studies were included, with a total of 1318 participants in the intervention group and 1115 participants in the placebo group. The included studies were listed in an ad hoc table describing direct and indirect comparisons of the different types of vitamins. Our findings showed that, in both pairwise comparison and frequentist network meta-analysis, the different types of oral vitamin supplements did not show statistically significant effects on arterial stiffness. However, when oral vitamin supplementation was longer than 12 weeks, vitamin D3 showed a significant reduction in arterial stiffness, compared with the placebo (ES: -0.15; 95% CI: -0.30, -0.00; -60.0% m/s) and vitamin D2 (ES: -0.25; 95% CI: -0.48, -0.02, -52.0% m/s). In summary, our study confirms that oral vitamin D3 supplementation for more than 12 weeks could be an effective approach to reduce arterial stiffness and could be considered a useful approach to improve vascular health in patients at high risk of cardiovascular disease.

Potential impact of the steroid hormone, vitamin D, on the vasculature

The role of vitamin D in the cardiovascular system is complex because it regulates expression of genes involved in diverse metabolic processes. Although referred to as a vitamin, it is more accurately considered a steroid hormone, because it is produced endogenously in the presence of ultraviolet light. It occurs as a series of sequentially activated forms, here referred to as vitamin D-hormones. A little-known phenomenon, based on pre-clinical data, is that its biodistribution and potential effects on vascular disease likely depend on whether it is derived from diet or sunlight. Diet-derived vitamin D-hormones are carried in the blood, at least in part, in chylomicrons and lipoprotein particles, including low-density lipoprotein. Since low-density lipoprotein is known to accumulate in the artery wall and atherosclerotic plaque, diet-derived vitamin D-hormones may also collect there, and possibly promote the osteochondrogenic mineralization associated with plaque. Also, little known is the fact that the body stores vitamin D-hormones in adipose tissue with a half-life on the order of months, raising doubts about whether the use of the term "daily requirement" is appropriate. Cardiovascular effects of vitamin D-hormones are controversial, and risk appears to increase with both low and high blood levels. Since low serum vitamin D-hormone concentration is reportedly associated with increased cardiovascular and orthopedic risk, oral supplementation is widely used, often together with calcium supplements. However, meta-analyses show that oral vitamin D-hormone supplementation does not protect against cardiovascular events, findings that are also supported by a randomized controlled trial. These considerations suggest that prevalent recommendations for vitamin D-hormone supplementation for the purpose of cardiovascular protection should be carefully reconsidered.

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

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

Vitamin D and Atherosclerotic Cardiovascular Disease

CONTEXT

A large body of experimental and observational data has implicated vitamin D deficiency in the development of cardiovascular disease. However, evidence to support routine vitamin D supplementation to prevent or treat cardiovascular disease is lacking.

DESIGN AND RESULTS

A comprehensive literature review was performed using PubMed and other literature search engines. Mounting epidemiological evidence and data from Mendelian randomization studies support a link between vitamin D deficiency and adverse cardiovascular health outcomes, but randomized trial evidence to support vitamin D supplementation is sparse. Current public health guidelines restrict vitamin D intake recommendations to the maintenance of bone health and prevention of fractures. Two recently published large trials (VITAL and ViDA) that assessed the role of moderate- to high-dose vitamin D supplementation as primary prevention for cardiovascular outcomes in the general population had null results, and previous randomized trials have also been generally negative. These findings from general population cohorts that are largely replete in vitamin D may not be applicable to chronic kidney disease (CKD) populations, in which the use of active (1α-hydroxylated) vitamin D compounds is prevalent, or to other high-risk populations. Additionally, recent trials in the CKD population, as well as trials using vitamin D analogs, have been limited.

CONCLUSIONS

Current randomized trials of vitamin D supplementation do not support benefits for cardiovascular health, but the evidence remains inconclusive. Additional randomized trials assessing larger numbers of participants with low baseline vitamin D levels, having longer follow-up periods, and testing higher vitamin D dosages are needed to guide clinical practice.

Vitamin D in Cardiovascular Disease

Cardiovascular disease is the prevalent cause of morbidity and mortality in the world, affecting many millions of individuals every year. Atherosclerosis, a chronic inflammatory condition that involves different cell types, several cytokines and adhesion molecules, is the underlying cause of cardiovascular disease. Vitamin D is known to control skeletal patho/physiology, regulating calcium and phosphorus and bone remodeling along with other calcium-regulating hormones. However, several active metabolites of vitamin D can exert both direct action, mainly via vitamin D₃ receptor trans-activation and indirect actions on several other tissues by an endocrine, autocrine and paracrine manners. With regard to cardiovascular disease, vitamin D deficiency has been associated with activation of the pro-inflammatory mechanism, promoting atherogenesis. There are several large-scale clinical studies, as well as meta-analyses that support this finding. However, it is still unclear whether the plasma 25-hydroxyvitamin D level can be used as a biomarker for future cardiovascular disease. Herein we review the studies reporting a causative role for vitamin D in cardiovascular disease.

Vitamin D and the Athlete: Current Perspectives and New Challenges

The last decade has seen a dramatic increase in general interest in and research into vitamin D, with many athletes now taking vitamin D supplements as part of their everyday dietary regimen. The most recognized role of vitamin D is its regulation of calcium homeostasis; there is a strong relationship between vitamin D and bone health in non-athletic individuals. In contrast, data have consistently failed to demonstrate any relationship between serum 25[OH]D and bone health, which may in part be due to the osteogenic stimulus of exercise. Vitamin D may interact with extra-skeletal tissues such as muscle and the immune system to modulate recovery from damaging exercise and infection risk. Given that many athletes now engage in supplementation, often consuming extreme doses of vitamin D, it is important to assess whether excessive vitamin D can be detrimental to health. It has been argued that toxic effects only occur when serum 25[OH]D concentrations are greater than 180 nmol·l^-1, but data from our laboratory have suggested high-dose supplementation could be problematic. Finally, there is a paradoxical relationship between serum 25[OH]D concentration, ethnicity, and markers of bone health: Black athletes often present with low serum 25[OH]D without physiological consequences. One explanation for this could be genetic differences in vitamin D binding protein due to ethnicity, resulting in greater concentrations of bioavailable (or free) vitamin D in some ethnic groups. In the absence of any pathology, screening may be unnecessary and could result in incorrect supplementation. Data must now be re-examined, taking into consideration bioavailable or "free" vitamin D in ethnically diverse groups to enable new thresholds and target concentrations to be established; perhaps, for now, it is time to "set vitamin D free".

Vitamin D in Neurological Diseases: A Rationale for a Pathogenic Impact

It is widely known that vitamin D receptors have been found in neurons and glial cells, and their highest expression is in the hippocampus, hypothalamus, thalamus and subcortical grey nuclei, and substantia nigra. Vitamin D helps the regulation of neurotrophin, neural differentiation, and maturation, through the control operation of growing factors synthesis (i.e., neural growth factor [NGF] and glial cell line-derived growth factor (GDNF), the trafficking of the septohippocampal pathway, and the control of the synthesis process of different neuromodulators (such as acetylcholine [Ach], dopamine [DA], and gamma-aminobutyric [GABA]). Based on these assumptions, we have written this review to summarize the potential role of vitamin D in neurological pathologies. This work could be titanic and the results might have been very fuzzy and even incoherent had we not conjectured to taper our first intentions and devoted our interests towards three mainstreams, demyelinating pathologies, vascular syndromes, and neurodegeneration. As a result of the lack of useful therapeutic options, apart from the disease-modifying strategies, the role of different risk factors should be investigated in neurology, as their correction may lead to the improvement of the cerebral conditions. We have explored the relationships between the gene-environmental influence and long-term vitamin D deficiency, as a risk factor for the development of different types of neurological disorders, along with the role and the rationale of therapeutic trials with vitamin D implementation.

Association of vitamin D deficiency and VDBP gene polymorphism with the risk of AMI in a Pakistani population

Objective

To investigate the relationship of vitamin D deficiency and risk of AMI in a Pakistani population, and to find out any association between vitamin D binding protein (VDBP) genotypes and risk of AMI in this population.

Methods

In a comparative cross-sectional study, 246 patients (age: 20-70 years; 171 males and 75 females) with first AMI were enrolled with informed consent. Similarly, 345 healthy adults (230 males and 115 females) were enrolled as controls. Their fasting serum samples were analyzed for 25 (OH) vitamin D, lipids and other biomarkers using kit methods, while DNA was analyzed for VDBP genotypes using PCR-RFLP based methods. Chi-squared test and logistic regression were used for association of vitamin D deficiency and VDBP genotypes with AMI.

Results

Mean serum concentration of 25(OH) vitamin D was significantly lower in AMI patients compared to healthy subjects (p=0.015) and percent vitamin D deficiency was higher in AMI patients compared to healthy subjects (p=0.003). VDBP IF-IF genotype was positively associated with the risk of AMI in subject above 45 years after adjusting for potential confounders [OR = 9.86; 95% CI=1.16 to 83.43].

Conclusion

Vitamin D deficiency and VDBP IF-IF genotype are associated with AMI in Pakistani adults.

Vitamin D and regulation of vascular cell function

Vitamin D deficiency is linked to pathogenesis of many diseases including cardiovascular, cancer, and various eye diseases. In recent years, important roles for vitamin D in regulation of immune function, inflammation, angiogenesis, and aging have been demonstrated. Thus, vitamin D and its analogs have been evaluated for the treatment of various types of cancer and chronic diseases. We have previously shown that the active form of vitamin D [1,25(OH)₂D₃] is a potent inhibitor of angiogenesis. This activity is consistent with the important role proposed for vitamin D and its analogs in the mitigation of tumor growth through inhibition of angiogenesis. Here, we review the important nutritional value of vitamin D and the abnormalities linked to its deficiency. We will explore its potential role as a regulator of angiogenesis and vascular cell function and the role vitamin D receptor (VDR) expression plays in these activities during vascular development and neovascularization. Our studies have established an important role for 1,25(OH)₂D₃ and VDR in the regulation of perivascular supporting cell function. In addition, the interaction of 1,25(OH)₂D₃ and VDR is essential for these activities and inhibition of neovascularization. Delineating the signaling pathways involved and identification of genes that are the target of 1,25(OH)₂D₃ regulation in vascular cells will allow us to identify novel pathways that are targets for regulation of vascular function and angiogenesis.

RNA Sequencing Exposes Adaptive and Immune Responses to Intrauterine Growth Restriction in Fetal Sheep Islets

The risk of type 2 diabetes is increased in children and adults who exhibited fetal growth restriction. Placental insufficiency and intrauterine growth restriction (IUGR) are common obstetrical complications associated with fetal hypoglycemia and hypoxia that reduce the β-cell mass and insulin secretion. In the present study, we have defined the underlying mechanisms of reduced growth and proliferation, impaired metabolism, and defective insulin secretion previously established as complications in islets from IUGR fetuses. In an IUGR sheep model that recapitulates human IUGR, high-throughput RNA sequencing showed the transcriptome of islets isolated from IUGR and control sheep fetuses and identified the transcripts that underlie β-cell dysfunction. Functional analysis expanded mechanisms involved in reduced proliferation and dysregulated metabolism that include specific cell cycle regulators and growth factors and mitochondrial, antioxidant, and exocytotic genes. These data also identified immune responses, wnt signaling, adaptive stress responses, and the proteasome as mechanisms of β-cell dysfunction. The reduction of immune-related gene expression did not reflect a change in macrophage density within IUGR islets. The present study reports the islet transcriptome in fetal sheep and established processes that limit insulin secretion and β-cell growth in fetuses with IUGR, which could explain the susceptibility to premature islet failure in adulthood. Islet dysfunction formed by intrauterine growth restriction increases the risk for diabetes.

Association of Serum 25-hydroxy-vitamin D Concentration and Arterial Stiffness among Korean Adults in Single Center

Background

There are growing concerns about the role of vitamin D deficiency in cardiovascular diseases. Therefore, we investigated the correlation between serum 25-hydroxy-vitamin D (25[OH]D) and arterial stiffness among Korean adults.

Methods

We retrospectively reviewed the medical charts of 302 people (115 women and 187 men) who visited a tertiary hospital from January 2015 to December 2016. Serum 25(OH)D was measured using the radioimmunoassay technique, and brachial-ankle pulse wave velocity (baPWV) was measured using an automatic wave analyzer. We obtained the doctor's report on the medical history of the participants, their alcohol consumption and smoking habits, and their exercise status. Metabolic syndrome was diagnosed based on guidelines from the National Cholesterol Education Program (NCEP)-Adult Treatment Panel (ATP III) and the International Diabetes Federation (IDF). Results of basic blood tests and physical assessment were also collected.

Results

In the Pearson correlation analysis, serum 25(OH)D and baPWV showed a statistically significant inverse relationship (r=-0.279, P<0.001). Using multiple regression analysis, and after adjusting for possible confounders, serum 25(OH)D concentration was found to be significantly associated with baPWV (β=-0.121, P=0.011).

Conclusions

We observed an association between serum 25(OH)D concentration and arterial stiffness. Further studies involving larger sample sizes will be needed to confirm this associations.

Vitamin D and its effects on cardiovascular diseases: a comprehensive review

Vitamin D is a molecule that is actively involved in multiple metabolic pathways. It is mostly known for its implications related to calcium metabolism. It has also been determined that it actively participates in the cardiovascular system, influencing blood pressure, coronary artery disease and other vascular diseases, such as heart failure and atrial fibrillation. Furthermore, it has been established that this vitamin is extensively involved in the regulation of both the renin angiotensin aldosterone system and the immune system. In this review, we present the different vitamin D metabolic pathways associated with the cardiovascular pathophysiology, and we include studies in animal and human models, as well as some of the controversies found in the literature. This review also incorporates an overview of the implications in the molecular biology and public health fields.

Effect of vitamin D supplementation on measures of arterial stiffness: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Low vitamin D has been associated with poor arterial compliance in observational studies. Arterial stiffness has prognostic value for cardiovascular disease risk. The aim of this systematic review was to clarify the literature surrounding the use of vitamin D to ameliorate arterial stiffness.

METHODS

We conducted a systematic review of the MEDLINE, Scopus and EMBASE databases for randomized controlled clinical trials investigating the effect of vitamin D supplementation on pulse wave velocity (PWV) and/or augmentation index (AI) as indicators of arterial stiffness. We meta-analysed data and calculated standardized mean difference (SMD) and 95% confidence intervals (CI) using inverse-variance models on RevMan v5.3 software. Study quality was assessed using a modified Jadad scale.

RESULTS

A total of 607 unique records were identified, of which 18 satisfied our inclusion and exclusion criteria. Study quality was high, ranging from 9 to 12 (of 13). Study design in terms of vitamin D dosing protocol (range: 1000-5700 IU/day), follow-up times (range: 1-12 months), sample size (range: n = 29-183) and recruitment strategies varied markedly. Thirteen studies had data for meta-analysis. Vitamin D was associated with nonsignificant reductions in PWV [SMD = -0·10; 95% CI: -0·24, 0·04; P = 0·17; n = 806 from ten studies] and AI [-0·15; -0·32, 0·02; 0·08; n = 551 from eight studies].

DISCUSSION

There is inconsistent evidence to suggest that vitamin D supplementation improves indicators of arterial stiffness. This may be attributable to the heterogeneity in study design. Therefore, large and well-designed randomized studies are required to determine the casual relationships between vitamin D and arterial stiffness and cardiovascular risk.

Investigation of Vitamin D-Binding Protein Polymorphism Impact on Coronary Artery Disease and Relationship with Longevity: Own Data and a Review

The aim of the study was to assess the effect of vitamin D-binding protein (DBP) polymorphism on coronary artery disease (CAD). DBP phenotypes were identified in the groups: control (n = 306), men suffering from CAD (n = 154), and long-lived individuals (n = 108). Isoelectric focusing of DBP phenotypes in serum was performed on polyacrylamide gel. Distribution of DBP phenotypes in the study groups was found to be in Hardy-Weinberg equilibrium. Gc1s-1s phenotype and Gc1s allele frequency in CAD groups were significantly higher than in control, and Gc1s allele frequency was found significantly more often in CAD compared with long-lived group (p < 0.05). The Gc2 allele frequency in control was higher as compared with Gc2 frequency in CAD group (p < 0.05). The Gc2-2 phenotype was more frequent in long-lived survivors than in the CAD group (p < 0.05). It was found that the Gc1s allele significantly increased the risk of CAD with the odds ratio (OR) equal to 1.45 (p < 0.02) and showed Gc2 to be related with a decreased risk of CAD (OR = 0.69; p < 0.03). Authors review the role of DBP in resistance to atherosclerosis and cancer as the main longevity determinants.

An efficacy of intensive vitamin D delivery to neointimal hyperplasia in recurrent vascular access stenosis

PURPOSE

Neointimal hyperplasia (NH) causes vascular access (VA) stenosis, which results in serious under-dialytic morbidity in hemodialysis patients. We sought to assess whether a vitamin D intervention to NH lesions leads to better VA patency and examined clinical and in vitro studies.

METHODS

A pilot clinical study of six hemodialysis patients was conducted to elucidate whether 0.5 μg calcitriol injection to stenotic lesion after balloon angioplasty (PTA) maintains better vessel patency until the next follow-up angiography. Localized vitamin D exposure was utilized by delivering and fixing calcitriol intensively at the stenotic lesion through a side-hole catheter with balloon clamping. We also performed vascular smooth muscle cell (VSMC) culture to detect both apoptosis (cell death detection assay) and cell viability (5-Bromo-2'-deoxy-uridine incorporation), and explored the efficacy of vitamin D to inhibit VSMC proliferation. Additionally, immunohistochemistry (IHC) was conducted to examine vitamin D receptor (VDR) expression at NH lesion, obtained from VA surgery.

RESULTS

Percent patency, the proportion between stenotic and non-stenotic vessel diameters, increased significantly (p = 0.03) after directly catheter-delivered 0.5 μg calcitriol administration. In vitro VSMC studies, 0.1 nM calcitriol significantly (p<0.05) enhanced apoptosis and cell-cycle inhibition for two different calcitriol exposure times (15 minutes and 24 hours). IHC staining revealed that VDR-positive hyperplastic cells were observed at NH lesion.

CONCLUSIONS

Intensive vitamin D exposure at NH lesion has an ability to inhibit further VSMC proliferation, and presumably leads to greater patency rate for recurrent VA stenosis. Further studies are needed to clarify whether its unique property is exhibited through VDR-mediated mechanism.

Modelling atherosclerosis by proteomics: Molecular changes in the ascending aortas of cholesterol-fed rabbits

The cholesterol-fed rabbit is commonly used as a model to study the vascular effects of hypercholesterolemia and resulting atherosclerotic lesions. Here we undertook a proteomic case-control investigation of ascending aortas from male New Zealand White rabbits after 10 weeks on a high-cholesterol (2% w/w) diet (HCD, n = 5) or control diet (n = 5), in order to determine the changes in response to the HCD. Histology confirmed intimal thickening in the HCD group consistent with atherosclerosis, and LC-MS/MS analysis of individually-obtained ascending aortic extracts labelled with isobaric (iTRAQ) tags enabled the identification and quantitation of 453 unique proteins above the 1% false discovery rate threshold. Of 67 proteins showing significant differences in relative abundance (p < 0.05), 62 were elevated and five decreased in ascending aortas from HCD-fed rabbits compared to controls. Six proteins were selected for validation using Multiple Reaction Monitoring, which confirmed the iTRAQ results. Many of the observed protein changes are consistent with known molecular perturbations in the ascending aorta that occur in response to hypercholesterolemia, e.g. elevation of tissue levels of apolipoproteins, extracellular matrix adhesion proteins, glycolytic enzymes, heat shock proteins and proteins involved in immune defense. We also made a number of novel observations, including a 15-fold elevation of glycoprotein (trans-membrane) nmb-like (Gpnmb) in response to HCD. Gpnmb has previously been linked to angiogenesis but not to atherosclerosis. This and additional novel observations merit further investigation as these perturbations may play important and as yet undiscovered roles in the pathogenesis of atherosclerosis in rabbits as well as humans.

Proteomic analysis of porcine endometrial tissue during peri-implantation period reveals altered protein abundance

In mammals, successful pregnancy depends upon the readiness of uterus for implantation, followed by correct communication between the endometrium and the developing conceptus. The objective of this study was to elucidate changes in protein abundance associated with progression of estrous cycle and pregnancy from Day 9 to Day 12. We analyzed porcine endometrial tissue lysates by 2D-DIGE. Abundance of several proteins was altered depending upon the pregnancy status of animals. MALDI-TOF/TOF was used to identify a number of these proteins. Endometrial proteins that increased from Day 9 to Day 12 of cycle included annexin A4, beta-actin, apolipoprotein, ceruloplasmin and afamin. Changes in protein abundances associated with conceptus secreted factors, including haptoglobin, prolyl-4-hydroxylase, aldose-reductase and transthyretin, were also observed. Functional analysis revealed that endometrial proteins with altered abundance on Day 12 irrespective of the reproductive status were related to growth and remodeling, acute phase response and free radical scavenging, whereas transport and small molecule biochemistry were the functions activated in the pregnant endometrium as compared to the cyclic endometrium. These data provide information on dynamic physiological processes associated with uterine endometrial function of the cyclic and pregnant endometrium during period of maternal recognition of pregnancy in pigs and may potentially demonstrate a protein profile associated with successful pregnancy.

BIOLOGICAL SIGNIFICANCE

In pigs, the fertility rates are generally very high but the early embryonic loss that occurs during the second and third weeks of gestation critically affects the potential litter size. Temporal changes that take place in the uterine environment during the period of early pregnancy in pigs and a cross-talk between the uterus and the embryo play an important role in embryonic survival and successful pregnancy. A better understanding of the molecular changes associated with these processes will pave way for understanding of endometrial functions and help towards increasing embryo survival. In this study, we present a 2D-DIGE based analysis of changes in porcine endometrial proteome that are associated with progression of cycle and progression of pregnancy. The network analysis of the results clearly revealed the pathways that are involved in rendering the endometrium receptive to the presence of embryo and also the changes that are result of molecular communication between the endometrium and the conceptuses. This comprehensive identification of proteomic changes in the porcine endometrium could be a foundation for targeted studies of proteins and pathways potentially involved in abnormal endometrial receptivity, placentation and embryo loss.

25-hydroxyvitamin D and parathyroid hormone levels do not predict changes in carotid arterial stiffness: the Multi-Ethnic Study of Atherosclerosis

OBJECTIVE

To evaluate the impact of vitamin D and parathyroid hormone (PTH) on longitudinal changes in arterial stiffness.

APPROACH AND RESULTS

Distensibility coefficient and Young's elastic modulus of the right common carotid artery were evaluated at baseline and after a mean (SD) of 9.4 (0.5) years in 2580 Multi-Ethnic Study of Atherosclerosis (MESA) participants. Cross-sectional and longitudinal associations were evaluated using multivariable linear regression and analysis of covariance. At baseline, participants were 60.1 (9.4) years old (54% female; 26% black, 20% Hispanic, 14% Chinese). Mean annualized 25(OH)D was <20 ng/dL in 816 participants, and PTH was >65 pg/dL in 285 participants. In cross-sectional analyses, low 25(OH)D (<20 ng/mL) was not associated with stiffer arteries after adjustment for cardiovascular disease risk factors (P>0.4). PTH >65 pg/mL was associated with stiffer arteries after adjustment for cardiovascular disease risk factors, other than systolic blood pressure (distensibility coefficient: β=-2.4×10(-4) mm Hg(-1), P=0.003; Young's elastic modulus: β=166 mm Hg, P=0.01); however, after adjustment for systolic blood pressure, these associations no longer were statistically significant. Longitudinal arterial stiffening was associated with older age (P<0.0001), higher systolic blood pressure (P<0.008), and use of antihypertensive medications (P<0.006), but not with 25(OH)D or PTH (both P>0.1).

CONCLUSIONS

Carotid arterial stiffness is not associated with low 25(OH)D concentrations. Cross-sectional associations between arterial stiffness and high PTH were attenuated by systolic blood pressure. After nearly a decade of follow-up, neither baseline PTH nor 25(OH)D concentrations were associated with progression of carotid arterial stiffness.

Vitamin D and cardiovascular disease

Vitamin D plays a classical hormonal role in skeletal health by regulating calcium and phosphorus metabolism. Vitamin D metabolites also have physiological functions in nonskeletal tissues, where local synthesis influences regulatory pathways via paracrine and autocrine mechanisms. The active metabolite of vitamin D, 1α,25-dihydroxyvitamin D, binds to the vitamin D receptor that regulates numerous genes involved in fundamental processes of potential relevance to cardiovascular disease, including cell proliferation and differentiation, apoptosis, oxidative stress, membrane transport, matrix homeostasis, and cell adhesion. Vitamin D receptors have been found in all the major cardiovascular cell types including cardiomyocytes, arterial wall cells, and immune cells. Experimental studies have established a role for vitamin D metabolites in pathways that are integral to cardiovascular function and disease, including inflammation, thrombosis, and the renin-angiotensin system. Clinical studies have generally demonstrated an independent association between vitamin D deficiency and various manifestations of degenerative cardiovascular disease including vascular calcification. However, the role of vitamin D supplementation in the management of cardiovascular disease remains to be established. This review summarizes the clinical studies showing associations between vitamin D status and cardiovascular disease and the experimental studies that explore the mechanistic basis for these associations.

Vitamin D binding protein: a multifunctional protein of clinical importance

Since the discovery of group-specific component and its polymorphism by Hirschfeld in 1959, research has put spotlight on this multifunctional transport protein (vitamin D binding protein, DBP). Besides the transport of vitamin D metabolites, DBP is a plasma glycoprotein with many important functions, including sequestration of actin, modulation of immune and inflammatory responses, binding of fatty acids, and control of bone development. A considerable DBP polymorphism has been described with a specific allele distribution in different geographic area. Multiple studies have shed light on the interesting relationship between polymorphisms of the DBP gene and the susceptibility to diseases. In this review, we give an overview of the multifunctional character of DBP and describe the clinical importance of DBP and its polymorphisms. Finally, we discuss the possibilities to use DBP as a novel therapeutic agent.

Vitamin D and cardiovascular disease: is the evidence solid?

Vitamin D deficiency, prevalent in 30-50% of adults in developed countries, is largely due to inadequate cutaneous production that results from decreased exposure to sunlight, and to a lesser degree from low dietary intake of vitamin D. Serum levels of 25-hydroxyvitamin D (25-OH D) <20 ng/mL indicate vitamin D deficiency and levels >30 ng/mL are considered optimal. While the endocrine functions of vitamin D related to bone metabolism and mineral ion homoeostasis have been extensively studied, robust epidemiological evidence also suggests a close association between vitamin D deficiency and cardiovascular morbidity and mortality. Experimental studies have demonstrated novel actions of vitamin D metabolites on cardiomyocytes, and endothelial and vascular smooth muscle cells. Low 25-OH D levels are associated with left ventricular hypertrophy, vascular dysfunction, and renin-angiotensin system activation. Despite a large body of experimental, cross-sectional, and prospective evidence implicating vitamin D deficiency in the pathogenesis of cardiovascular disease, a causal relationship remains to be established. Moreover, the cardiovascular benefits of normalizing 25-OH D levels in those without renal disease or hyperparathyroidism have not been established, and questions of an epiphenomenon where vitamin D status merely reflects a classic risk burden have been raised. Randomized trials of vitamin D replacement employing cardiovascular endpoints will provide much needed evidence for determining its role in cardiovascular protection.

The effect of vitamin D status on risk factors for cardiovascular disease

Vitamin-D-related pathways are implicated in various endocrine, inflammatory and endothelial functions. An estimated 1 billion people in the world have vitamin D deficiency or insufficiency, and undiagnosed vitamin D deficiency is common. Vitamin D deficiency is associated with substantial increases in the incidence of hypertension, hyperlipidaemia, myocardial infarction and stroke, as well as in diseases such as chronic kidney disease and type 2 diabetes. Low vitamin D levels also upregulate the renin-angiotensin-aldosterone system, increase inflammation and cause endothelial dysfunction. However, the role of vitamin D deficiency in cardiovascular morbidity and mortality is an emerging and hotly debated topic. Epidemiological studies suggest an association between low vitamin D levels and risk factors for cardiovascular disease, but a causal relationship has not been established, and clinical trials and meta-analyses have not demonstrated convincing evidence that vitamin D therapy improves cardiovascular outcomes. Some evidence suggests that vitamin D status is a biomarker of lifestyle, since unhealthy and sedentary lifestyles are associated with vitamin D insufficiency or deficiency and are also risk factors for cardiovascular complications.

Vitamin D-binding protein interacts with Aβ and suppresses Aβ-mediated pathology

The level of vitamin D-binding protein (DBP) is increased in the cerebrospinal fluid of patients with Alzheimer's disease (AD), suggesting a relationship with its pathogenesis. In this study, we investigated whether and how DBP is related to AD using several different approaches. A pull-down assay and a surface plasmon resonance binding assay indicated direct interactions between purified DBP and amyloid beta (Aβ), which was confirmed in the brain of AD patients and transgenic AD model mice by immunoprecipitation assay and immunohistochemical double-staining method. Moreover, atomic force microscopic examination revealed that DBP reduced Aβ aggregation in vitro. DBP also prevented Aβ-mediated death in cultured mouse hippocampal HT22 cell line. Finally, DBP decreased Aβ-induced synaptic loss in the hippocampus and rescued memory deficits in mice after injection of Aβ into the lateral ventricle. These results provide converging evidence that DBP attenuates the harmful effects of Aβ by a direct interaction, and suggest that DBP is a promising therapeutic agent for the treatment of AD.

Arterial stiffness and vitamin D levels: the Baltimore longitudinal study of aging

CONTEXT

The importance of vitamin D for bone health has long been acknowledged. Recent evidence suggests that vitamin D can also play a role in reducing the risk of several other diseases, including cardiovascular disease.

OBJECTIVE

The aim of this study is to test the hypothesis that 25-hydroxyvitamin D (25-OH D) is an independent cross-sectional correlate of central arterial stiffness in a normative aging study population.

DESIGN AND SETTINGS

We conducted a cross-sectional analysis.

SUBJECTS

We studied 1228 healthy volunteers (50% males; age, 70±12 yr) of the Baltimore Longitudinal Study of Aging.

MAIN OUTCOME MEASURES

We measured carotid-femoral pulse wave velocity (PWV) and 25-OH D levels.

RESULTS

We found a significant inverse association between PWV and 25-OH D levels (adjusted r2=0.27; β=-0.43; P=0.001). After adjusting for age, gender, ethnicity, season of blood draw, estimated glomerular filtration rate, physical activity level, cardiovascular risk factors score (smoking, visceral obesity, hypercholesterolemia, hypertension, and diabetes), calcium/vitamin D supplementation, serum calcium, and PTH levels, the association between PWV and 25-OH D levels was only slightly reduced and remained statistically significant (adjusted r2=0.34; β=-0.34; P=0.04).

CONCLUSIONS

Vitamin D levels are inversely associated with increased arterial stiffness in a normative aging population, irrespective of traditional risk factor burden. Further research is needed to understand the mechanism of this association and to test the hypothesis that vitamin D supplementation can reduce arterial stiffness.

Vitamin D deficiency and arterial wall stiffness in children with chronic kidney disease

Arterial wall stiffness is a recognized complication in children with chronic kidney disease (CKD). Vascular abnormalities in these patients are shown to predate cardiac abnormalities such as left ventricular hypertrophy and diastolic dysfunction. The etiology of vascular abnormalities in these patients currently is not clear. This study explored the relationship between various parameters of calcium-phosphorus metabolism including 25-hydroxy vitamin D and arterial wall stiffness in pediatric patients with CKD. This study investigated a cohort of 43 children with CKD who had no history of underlying congenital or structural cardiac disease. The Augmentation Index (AI), a measure of peripheral arterial reflective properties using radial artery tonometry, was used as an indirect measure of central aortic stiffness. Serum biochemical markers of calcium-phosphorus metabolism were simultaneously measured. Univariate testing showed that AI correlated with worsening kidney function. Serum 25-hydroxy vitamin D levels were low and correlated negatively with AI (r = -0.39; p < 0.05). Multiple regression analysis showed that 25-hydroxy vitamin D was the only significant independent predictor of increased central arterial stiffness in the subgroup of children receiving hemodialysis. No association was observed between AI and any other measured biochemical parameter of calcium-phosphorus metabolism. This is the first study to investigate pediatric patients with CKD that suggests an association between nutritional vitamin D deficiency and increased arterial stiffness in children with CKD. The pathophysiologic mechanisms of vitamin D that regulate increased arterial stiffness need to be integrated further in pediatric CKD patients.

Biomarker discovery in serum from patients with carotid atherosclerosis

BACKGROUND

Blood-based biomarkers of atherosclerosis have been used to identify patients at high risk for developing stroke. We hypothesized that patients with carotid artery disease would have a distinctive proteomic signature in blood as compared to a healthy control population without carotid artery disease. In order to discover protein biomarkers associated with increased atherosclerotic risk, we used two different strategies to identify biomarkers from patients with clinically defined atherosclerosis who were undergoing endarterectomy for atherosclerotic carotid artery disease. These patients were compared with healthy matched controls.

METHODS

Serum was obtained from patients undergoing endarterectomy (EA; n = 38) and compared to a group of age-matched healthy controls (n = 40). Serum was fractionated using anion exchange chromatography and three different surface-enhanced laser desorption/ionization (SELDI) chip surfaces and then evaluated with mass spectrometry (MS) and two-dimensional difference gel electrophoresis (2D-DIGE).

RESULTS

A random forest (RF) analysis of the SELDI-MS protein peak data distinguished these two groups with 69.2% sensitivity and 73.2% specificity. Four unique SELDI peaks (4.2, 4.4, 16.7 and 28 kDa, all p< 0.01) showed the greatest influence in the RF model. The EA patients with a history of prior clinical atherosclerotic plaque rupture manifested as either stroke or transient ischemic attack (symptomatic; n = 16) were compared to patients with carotid atherosclerosis but no clinical evidence of plaque rupture (asymptomatic; n = 22). Analysis of the SELDI spectra did not separate these two patient subgroups. A subgroup analysis using 2D-DIGE images obtained from albumin-depleted serum comparing symptomatic (n = 10) to asymptomatic EA patients (n = 10) found 4 proteins that were differentially expressed (p < 0.01) in the symptomatic patients. These proteins were identified as α(1)-antitrypsin, haptoglobin and vitamin D binding protein that were downregulated and α(2)-glycoprotein precursor that was upregulated in the symptomatic EA group.

CONCLUSIONS

SELDI-MS data analysis of fractionated serum suggests that a distinct protein signature exists in patients with carotid atherosclerosis compared to age-matched healthy controls. Identification of 4 proteins in a subset of patients with symptomatic and asymptomatic carotid atherosclerosis suggests that these and other protein biomarkers may assist in identifying high-risk patients with carotid atherosclerosis.

Vitamin D status is associated with arterial stiffness and vascular dysfunction in healthy humans

OBJECTIVES

The primary objective of this study was to elucidate mechanisms underlying the link between vitamin D status and cardiovascular disease by exploring the relationship between 25-hydroxyvitamin D (25-OH D), an established marker of vitamin D status, and vascular function in healthy adults.

BACKGROUND

Mechanisms underlying vitamin D deficiency-mediated increased risk of cardiovascular disease remain unknown. Vitamin D influences endothelial and smooth muscle cell function, mediates inflammation, and modulates the renin-angiotensin-aldosterone axis. We investigated the relationship between vitamin D status and vascular function in humans, with the hypothesis that vitamin D insufficiency will be associated with increased arterial stiffness and abnormal vascular function.

METHODS

We measured serum 25-OH D in 554 subjects. Endothelial function was assessed as brachial artery flow-mediated dilation, and microvascular function was assessed as digital reactive hyperemia index. Carotid-femoral pulse wave velocity and radial tonometry-derived central augmentation index and subendocardial viability ratio were measured to assess arterial stiffness.

RESULTS

Mean 25-OH D was 31.8 ± 14 ng/ml. After adjustment for age, sex, race, body mass index, total cholesterol, low-density lipoprotein, triglycerides, C-reactive protein, and medication use, 25-OH D remained independently associated with flow-mediated vasodilation (β = 0.1, p = 0.03), reactive hyperemia index (β = 0.23, p < 0.001), pulse wave velocity (β = -0.09, p = 0.04), augmentation index (β = -0.11, p = 0.03), and subendocardial viability ratio (β = 0.18, p = 0.001). In 42 subjects with vitamin D insufficiency, normalization of 25-OH D at 6 months was associated with increases in reactive hyperemia index (0.38 ± 0.14, p = 0.009) and subendocardial viability ratio (7.7 ± 3.1, p = 0.04), and a decrease in mean arterial pressure (4.6 ± 2.3 mm Hg, p = 0.02).

CONCLUSIONS

Vitamin D insufficiency is associated with increased arterial stiffness and endothelial dysfunction in the conductance and resistance blood vessels in humans, irrespective of traditional risk burden. Our findings provide impetus for larger trials to assess the effects of vitamin D therapy in cardiovascular disease.

Vitamin D deficiency and toxicity in chronic kidney disease: in search of the therapeutic window

Both vitamin D deficiency and vitamin D toxicity are associated with cardiovascular complications in chronic kidney disease (CKD). Clinical and experiment data indicate that the association of vitamin D levels with cardiovascular disease is best illustrated as a biphasic, or U-shaped, curve. Children and adolescents with CKD need vitamin D due to the demands of a growing skeleton, to prevent renal rickets. However, this therapy carries the risk of severe side effects and chronic toxicity. Observational studies show that vitamin D deficiency and toxicity are frequently present in patients with CKD. In view of the importance of cardiovascular complications for the long-term survival of young patients, these findings demand a judicious use of vitamin D preparations. In clinical practice, the therapeutic window is rather small, presenting a therapeutic challenge to avoid both vitamin D deficiency and toxicity.

Proteomics of specific treatment-related alterations in Fabry disease: a strategy to identify biological abnormalities

Fabry disease is inherited as an X-linked disorder secondary to deficiency of alpha-galactosidase A, resulting in abnormal metabolism of substances containing alpha-d-galactosyl moieties. As a consequence, a multisystem disorder develops, culminating in strokes, progressive renal, and cardiac dysfunction. Signs and symptoms of Fabry disease become manifest in childhood, but diagnosis is often delayed. Thirteen children with Fabry disease (age range, 6.5-17 years) were studied as part of a 6-month open-label study of enzyme replacement therapy (ERT) with agalsidase alfa. Paired serum samples were drawn at the start of the study and after 6 months of ERT. Global protein changes in paired samples were compared by using differential stable isotope labeling of peptide lysine residues with O-methylisourea and subsequent nanoHPLC-tandem MS. Statistically significant decreases were observed for five proteins following ERT: alpha(2)-HS glycoprotein, vitamin D-binding protein, transferrin, Ig-alpha-2 C chain, and alpha-2-antiplasmin. The presence of low levels of alpha-2-antiplasmin and plasminogen was confirmed by alternate means in 34 consecutive patients, including four of five ERT-naïve subjects. Decreased alpha-2-antiplasmin was associated with a parallel increase in circulating VEGF. Soluble VEGF receptor-2 was significantly elevated in plasma of patients compared with pediatric controls and decreased with ERT. These results suggest previously unknown abnormalities of fibrinolysis and angiogenesis factors in Fabry disease. We demonstrated the feasibility of identifying treatment-specific alterations in a small number of subjects that point to previously unsuspected disease-related biological abnormalities.

Vitamin D and vascular calcification

PURPOSE OF REVIEW

Vascular calcification is frequently found in patients with osteoporosis, atherosclerosis and chronic kidney disease, leading to high morbidity and mortality rates. The effects of vitamin D excess and deficiency on vascular calcification are reviewed in this article.

RECENT FINDINGS

There is evidence from experimental studies that mediacalcinosis induced by vitamin D excess is an active and reversible process. Vitamin D excess, however, is rarely seen in the general human population. Experimental data also demonstrate that physiologic vitamin D actions include the inhibition of processes that are important for intimal and medial artery calcification such as pro-inflammatory cytokine release, adhesion molecule release, and proliferation and migration of vascular smooth muscle cells. In uremic rats, low levels of the vitamin D hormone calcitriol are associated with massive vascular and soft tissue calcifications. Whereas retrospective studies already indicate a beneficial effect of active vitamin D on mortality rates in chronic kidney disease, little is yet known about the effect of vitamin D deficiency on cardiovascular morbidity and mortality in the general population.

SUMMARY

Available data indicate that vitamin D exerts a biphasic 'dose response' curve on vascular calcification with deleterious consequences not only of vitamin D excess but also of vitamin D deficiency.

Nitrogen-rich coatings for promoting healing around stent-grafts after endovascular aneurysm repair

Complications following endovascular aneurysm repair (EVAR) are related to deficient healing around the stent-graft (SG). New generations of SG with surface properties that foster vascular repair could overcome this limitation. Our goal was to evaluate the potential of a new nitrogen-rich plasma-polymerised biomaterial, designated PPE:N, as an external coating for polyethylene terephtalate (PET)- or polytetrafluoro-ethylene (PTFE)-based SGs, to promote healing around the implant. Thin PPE:N coatings were deposited on PET and PTFE films. Then, adhesion, growth, migration and resistance to apoptosis of vascular smooth muscle cells (VSMCs) and fibroblasts, as well as myofibroblast differentiation, were assessed in vitro. In another experimental group, chondroitin sulphate (CS), a newly described mediator of vascular repair, was added to normal culture medium, to search for possible additional benefit. PPE:N-coatings, especially on PET, increased and accelerated cell adhesion and growth, compared with control PET and with standard polystyrene culture plates (PCP). PPE:N was also found to increase the resistance to apoptosis in VSMC, an important finding as aneurysms are characterised by VMSC depletion caused by a pro-apoptotic phenotype. Addition of CS in solution further increased migration and resistance to apoptosis. In conclusion, PPE:N-coating and/or CS could promote vascular repair around SGs following EVAR.

Effects of caveolin-1 on the 17beta-estradiol-mediated inhibition of VSMC proliferation induced by vascular injury

Estrogen has a protective effect on the cardiovascular system. Yet the mechanism of how estrogen inhibits vascular smooth muscle cell (VSMC) proliferation after vascular injury and the role of caveolin-1 in this process are not clear. To understand the protection effect of estrogen and caveolin-1, we employed a vascular balloon-injury model. Sixteen New Zealand White rabbits with or without estrogen were tested. 17beta-estradiol is able to inhibit VSMC proliferation in a range from 10(-10)-10(-5) mol/L, with an optimal concentration of 10(-8) mol/L. Estrogen exerted its effect through suppressing the activity of p42/44 MAPK, which can be blocked by tamoxifen. Moreover, in estrogen pretreated cells as well as in common carotid arteries of the balloon injury model, expression of caveolin-1 is enhanced compared to the estrogen-deficient group, as assessed by both western blotting and RT-PCR and morphological studies. Our results showed that the inhibition effect of estrogen in VSMCs is mediated by p42/44 MAPK. Caveolin-1 plays an important role in this protective process.

A proteomic approach for the characterization of C677T mutation of the human gene methylenetetrahydrofolate reductase

Methylenetetrahydrofolate reductase (MTHFR) catalyzes the conversion of methylenetetrahydrofolate (CH2H4folate) to methyltetrahydrofolate (CH3H4folate). The C677T mutation is a common polymorphism of the human enzyme that leads to the replacement of Ala222Val, thermolability of MTHFR, and mild elevation of plasma homocysteine levels. A mild hyperhomocysteinemia is known to be risk factor for cardiovascular and thrombotic diseases, ischemic stroke, neural tube defects, late on-set dementia, and pregnancy complications. Human plasma of subjects carrying the C677T mutation in the MTHFR gene has been investigated for their protein pattern in order to identify novel molecular hallmarks. 2-D analysis of the plasma protein allowed the identification of a specific pattern associated with the TT mutant genotype. Noteworthy, we found one spot shifted to a more basic pI in mutant individuals, and MS identification corresponded to vitamin D-binding protein (DBP or group component (Gc) globulin). MS/MS peptide sequencing allowed to discriminate different allelic variants in the investigated clinical groups. These data confirmed by molecular genetic analysis highlight the novel association between the C677T MTHFR genotype with the Gc2 polymorphism of the DBP. Moreover, we found a quantitative reduction of Apolipoprotein A-I in mutant individuals, which was associated, in previous studies by others to an increased cardiovascular risk.

Perlecan proteolysis induces an alpha2beta1 integrin- and Src family kinase-dependent anti-apoptotic pathway in fibroblasts in the absence of focal adhesion kinase activation

Dysregulation of apoptosis in endothelial cells (EC) and fibroblasts contributes to fibrosis. We have shown previously that apoptosis of EC triggers the proteolysis of extracellular matrix components and the release of a C-terminal fragment of perlecan, which in turn inhibits apoptosis of fibroblasts. Here we have defined the receptors and pathways implicated in this anti-apoptotic response in fibroblasts. Neutralizing alpha2beta1 integrin activity in fibroblasts exposed to either medium conditioned by apoptotic EC (SSC) or a recombinant perlecan C-terminal fragment (LG3) prevented resistance to apoptosis and is associated with decreased levels of Akt phosphorylation. Co-incubation of fibroblasts for 24 h with SSC or LG3 in the presence of PP2 (AG1879), a biochemical inhibitor of Src family kinases (SFKs) and focal adhesion kinase, showed a significantly decreased anti-apoptotic response. However, focal adhesion kinase gene silencing with RNA interference did not inhibit the anti-apoptotic response in fibroblasts. Src phosphorylation was increased in fibroblasts exposed to SSC, and transfection of fibroblasts with constitutively active Src mutants induced an anti-apoptotic response that was not further increased by SSC. Also, Src(-/-)Fyn(-/-) fibroblasts failed to mount an anti-apoptotic response in presence of SSC for 24 h but developed a complete anti-apoptotic response when exposed to SSC for 7 days. These results suggest that extracellular matrix fragments produced by apoptotic EC initiate a state of resistance to apoptosis in fibroblasts via an alpha2beta1 integrin/SFK (Src and Fyn)/phosphatidylinositol 3-kinase (PI3K)-dependent pathway. In the long term, additional SFK members are recruited for sustaining the anti-apoptotic response, which could play crucial roles in abnormal fibrogenic healing.

Biological and clinical aspects of the vitamin D binding protein (Gc-globulin) and its polymorphism

The vitamin D binding protein (DBP) is the major plasma carrier protein of vitamin D and its metabolites. Unlike other hydrophobic hormone-binding systems, it circulates in a considerably higher titer compared to its ligands. Apart from its specific sterol binding capacity, DBP exerts several other important biological functions such as actin scavenging, fatty acid transport, macrophage activation and chemotaxis. The DBP-gene is a member of a multigene cluster that includes albumin, alpha-fetoprotein, and alpha-albumin/afamin. All four genes are expressed predominantly in the liver with overlapping developmental profiles. DBP is a highly polymorphic serum protein with three common alleles (Gc1F, Gc1S and Gc2) and more than 120 rare variants. The presence of unique alleles is a useful tool for anthropological studies to discriminate and to reveal ancestral links between populations. Many studies have discussed the link between DBP-phenotypes and susceptibility or resistance to osteoporosis, Graves' disease, Hashimoto's thyroiditis, diabetes, COPD, AIDS, multiple sclerosis, sarcoidosis and rheumatic fever. This article reviews the general characteristics, functions and clinical aspects of DBP.