1,25-Dihydroxyvitamin-D3 treatment reduces cardiac hypertrophy and left ventricular diameter in spontaneously hypertensive heart failure-prone (cp/+) rats independent of changes in serum leptin

An overview of nutritional factors in the aetiopathogenesis of myocardial fibrosis in great apes

The main cause of mortality in great apes in zoological settings is cardiovascular disease (CVD), affecting all four taxa: chimpanzee (Pan troglodytes), bonobo (Pan paniscus), gorilla (Gorilla spp.) and orangutan (Pongo spp.). Myocardial fibrosis, the most typical histological characterisation of CVD in great apes, is non-specific, making it challenging to understand the aetiopathogenesis. A multifactorial origin of disease is assumed whereby many potential causative factors are directly or indirectly related to the diet, which in wild-living great apes mainly consists of high-fibre, low-carbohydrate and very low-sodium components. Diets of great apes housed in zoological settings are often different compared with the situation in the wild. Moreover, low circulating vitamin D levels have recently been recognised in great apes housed in more northern regions. Evaluation of current supplementation guidelines shows that, despite implementation of different dietary strategies, animals stay vitamin D insufficient. Therefore, recent hypotheses designate vitamin D deficiency as a potential underlying factor in the pathogenesis of myocardial fibrosis. The aim of this literature review is to: (i) examine important differences in nutritional factors between zoological and wild great ape populations; (ii) explain the potential detrimental effects of the highlighted dietary discrepancies on cardiovascular function in great apes; and (iii) elucidate specific nutrition-related pathophysiological mechanisms that may underlie the development of myocardial fibrosis. This information may contribute to understanding the aetiopathogenesis of myocardial fibrosis in great apes and pave the way for future clinical studies and a more preventive approach to great ape CVD management.

The association between vitamin D deficiency and the clinical outcomes of hospitalized COVID-19 patients

Background

Vitamin D deficiency is an emerging public health problem that affects more than one billion people worldwide. Vitamin D has been shown to be effective in preventing and reducing the severity of viral respiratory diseases, including influenza. However, the role of vitamin D in COVID-19 infection remains controversial. This study aimed to analyze the association of vitamin D deficiency on the clinical outcome of hospitalized COVID-19 patients.

Methods

A prospective cohort study was conducted among hospitalized COVID-19 patients at two COVID-19 referral hospitals in Indonesia from October 2021 until February 2022.

Results

The median serum 25(OH)D level in 191 hospitalized COVID-19 patients was 13.6 [IQR=10.98] ng/mL. The serum 25(OH)D levels were significantly lower among COVID-19 patients with vitamin D deficiency who had cardiovascular disease (p-value=0.04), the use of a ventilator (p-value=0.004), more severe COVID-19 cases (p-value=0.047), and mortality (p-value=0.002). Furthermore, serum 25(OH)D levels were significantly different between patients with mild and severe COVID-19 cases (p-value=0.019). Serum 25(OH)D levels in moderate and severe COVID-19 cases were significantly different (p-value=0.031). Lower serum 25(OH)D levels were significantly associated with an increased number of comorbidities (p-value=0.03), the severity of COVID-19 (p-value=0.002), and the use of mechanical ventilation (p-value=0.032). Mortality was found in 7.3% of patients with deficient vitamin D levels. However, patients with either sufficient or insufficient vitamin D levels did not develop mortality.

Conclusions

COVID-19 patients with vitamin D deficiency were significantly associated with having cardiovascular disease, mortality, more severe COVID-19 cases, and the used of mechanical ventilation. Lower serum 25(OH)D levels were associated with an increased number of comorbidities, COVID-19 severity, and the use of mechanical-ventilation. Thus, we suggest hospitalized COVID-19 patients to reach a sufficient vitamin D status to improve the clinical outcome of the disease.

The Role of Vitamin D and Its Molecular Bases in Insulin Resistance, Diabetes, Metabolic Syndrome, and Cardiovascular Disease: State of the Art

In the last decade, an increasing awareness was directed to the role of Vitamin D in non-skeletal and preventive roles for chronic diseases. Vitamin D is an essential hormone in regulating calcium/phosphorous balance and in the pathogenesis of inflammation, insulin resistance, and obesity. The main forms of vitamin D, Cholecalciferol (Vitamin D3) and Ergocalciferol (Vitamin D2) are converted into the active form (1,25-dihydroxyvitamin D) thanks to two hydroxylations in the liver, kidney, pancreas, and immune cells. Some anti-inflammatory cytokines are produced at higher levels by vitamin D, while some pro-inflammatory cytokines are released at lower levels. Toll-Like Receptor (TLR) expression is increased, and a pro-inflammatory state is also linked to low levels of vitamin D. Regardless of how it affects inflammation, various pathways suggest that vitamin D directly improves insulin sensitivity and secretion. The level of vitamin D in the body may change the ratio of pro- to anti-inflammatory cytokines, which would impact insulin action, lipid metabolism, and the development and function of adipose tissue. Many studies have demonstrated an inverse relationship between vitamin D concentrations and pro-inflammatory markers, insulin resistance, glucose intolerance, metabolic syndrome, obesity, and cardiovascular disease. It is interesting to note that several long-term studies also revealed an inverse correlation between vitamin D levels and the occurrence of diabetes mellitus. Vitamin D supplementation in people has controversial effects. While some studies demonstrated improvements in insulin sensitivity, glucose, and lipid metabolism, others revealed no significant effect on glycemic homeostasis and inflammation. This review aims to provide insight into the molecular basis of the relationship between vitamin D, insulin resistance, metabolic syndrome, type 1 and 2 diabetes, gestational diabetes, and cardiovascular diseases.

How Do Minerals, Vitamins, and Intestinal Microbiota Affect the Development and Progression of Heart Disease in Adult and Pediatric Patients?

Cardiovascular diseases (CVDs) are the leading cause of death worldwide, far ahead of cancer. Epidemiological data emphasize the participation of many risk factors that increase the incidence of CVDs, including genetic factors, age, and sex, but also lifestyle, mainly nutritional irregularities and, connected with them, overweight and obesity, as well as metabolic diseases. Despite the importance of cardiovascular problems in the whole society, the principles of prevention of CVDs are not widely disseminated, especially among the youngest. As a result, nutritional neglect, growing from childhood and adolescence, translates into the occurrence of numerous disease entities, including CVDs, in adult life. This review aimed to draw attention to the role of selected minerals and vitamins in health and the development and progression of CVDs in adults and children. Particular attention was paid to the effects of deficiency and toxicity of the analyzed compounds in the context of the cardiovascular system and to the role of intestinal microorganisms, which by interacting with nutrients, may contribute to the development of cardiovascular disorders. We hope this article will draw the attention of society and the medical community to emphasize promoting healthy eating and proper eating habits in children and adults, translating into increased awareness and a reduced risk of CVD.

Association between serum 25(OH)D and risk of all-cause mortality in adults with prior cardiovascular disease: a cohort study from NHANES 2007-2018

BACKGROUND

Serum vitamin D deficiency is common in the patients with cardiovascular disease (CVD), but the association between serum vitamin D levels and risk of all-cause mortality in patients with CVD is controversial.

OBJECTIVE

This study aimed to understand better the association between serum 25(OH)D status and risk of all-cause mortality in patients with prior CVD.

METHOD

We conducted a cohort study using data from the National Health and Nutrition Examination Survey from 2007 to 2018 to investigate the association between serum 25(OH)D and the risk of all-cause mortality using multivariate Cox regression models, with further subgroup analyses and interactions smooth curve fitting to address possible nonlinearities.

RESULT

A total of 3220 participants with prior CVD were included in this study, with a total of 930 deaths over a median follow-up of 5.52 years, with multivariable-adjusted serum vitamin D levels after natural log transformation (4.31-4.5 ) as a reference in COX regression, and corrected HRs and 95% CIs of 1.81 (1.31, 2.50), 1.34 (1.07, 1.66), 1.28 (1.05, 1.56),1.00 (reference), 1.10 (0.89, 1.37) for all-cause mortality, respectively. Results remained robust in the stratified analysis of interactions, but a L-shaped relationship was detected. We identified an inflection point of 4.5 after multivariate adjustment through a two-stage linear regression model and recursive algorithm.

CONCLUSION

Our findings demonstrate that increasing serum 25(OH)D levels may have a L-shaped relationship with risk of all-cause mortality and that increases in serum 25(OH)D levels do not continue to reduce the risk of all-cause mortality.

Circulating microRNAs as potential biomarkers of early vascular damage in vitamin D deficiency, obese, and diabetic patients

Vitamin D3 deficiency, obesity, and diabetes mellitus (DM) have been shown to increase the risk of cardiovascular diseases (CVDs). However, the early detection of vascular damage in those patients is still difficult to ascertain. MicroRNAs (miRNAs) are recognized to play a critical role in initiation and pathogenesis of vascular dysfunction. Herein, we aimed to identify circulating miRNA biomarkers of vascular dysfunction as early predictors of CVDs. We have recruited 23 middle-aged Emiratis patients with the following criteria: A healthy control group with vitamin D ≥ 20ng, and BMI < 30 (C1 group = 11 individuals); A vitamin D deficiency (Vit D level ≤ 20 ng) and obese (BMI ≥ 30) group (A1 group = 9 patients); A vitamin D deficiency, obese, plus DM (A2 group = 3 patients). Arterial stiffness via pulse wave velocity (PWV) was measured and the whole transcriptome analysis with qPCR validation for miRNA in plasma samples were tested. PWV relative to age was significantly higher in A1 group 19.4 ± 4.7 m/s and A2 group 18.3 ± 1.3 m/s compared to controls 14.7 ± 2.1 m/s (p < 0.05). Similar patterns were also observed in the Augmentation pressure (AP) and Alx%. Whole RNA-Sequencing revealed miR-182-5p; miR-199a-5p; miR-193a-5p; and miR-155-5p were differentially over-expressed (logFC > 1.5) in high-risk patients for CVDs vs healthy controls. Collectively, our result indicates that four specific circulating miRNA signature, may be utilized as non-invasive, diagnostic and prognostic biomarkers for early vascular damage in patients suffering from vitamin D deficiency, obesity and DM.

Vitamin D deficiency attenuates endothelial function by reducing antioxidant activity and vascular eNOS expression in the rat microcirculation

This study examined the effects of vitamin D deficiency on vascular function and tissue oxidative status in the microcirculation; and whether or not these effects can be ameliorated with calcitriol, the active vitamin D metabolite. Three groups (n = 10 each) of male Sprague Dawley rats were fed for 10 weeks with control diet (CR), vitamin D-deficient diet without (DR), or with oral calcitriol supplementation (0.15 μg/kg) for the last four weeks (DSR). After 10 weeks, rats were sacrificed; mesenteric arterial rings were studied using wire myograph. Oxidative stress biomarkers malondialdehyde (MDA) levels and superoxide dismutase (SOD) activity were measured in the mesenteric arterial tissue. Vascular protein expression of endothelial nitric oxide synthase (eNOS) was determined by Western blotting. Acetylcholine-induced endothelium-dependent relaxation of DR was lower than CR. eNOS expression and SOD activity were lower in mesenteric arterial tissue of DR compared to CR. Calcitriol supplementation to DSR did not ameliorate the above parameters; in fact, augmented endothelium-dependent contraction was observed. Serum calcium was higher in DSR compared to CR and DR. In conclusion, vitamin D deficiency impaired microvascular vasodilation, associated with eNOS downregulation and reduced antioxidant activity. Calcitriol supplementation to vitamin D-deficient rats at the dosage used augmented endothelium-dependent contraction, possibly due to hypercalcaemia.

Association of Serum 25-Hydroxyvitamin D Concentrations With All-Cause and Cause-Specific Mortality Among Adult Patients With Existing Cardiovascular Disease

Background: Vitamin D insufficiency and deficiency are common in patients with cardiovascular disease (CVD). We aimed to prospectively examine the associations of serum 25-hydroxyvitamin D [25(OH)D] concentrations with all-cause and cause-specific mortality among adult patients with existing CVD.

Methods: We included 37,079 patients with CVD from the UK Biobank study, a prospective cohort of half a million participants aged 40–69 years. We defined patients with CVD as those who suffered coronary heart disease, atrial fibrillation, heart failure, or stroke. The associations of serum 25(OH)D concentration with all-cause and cause-specific mortality were examined by using multivariable Cox regression models and competing risk analyses.

Results: Among 37,079 patients with CVD at baseline, 57.5% were subjected to vitamin D deficiency (i.e., 25[OH]D <50 nmol/L). During a median follow-up of 11.7 years, 6,319 total deaths occurred, including 2,161 deaths from CVD, 2,230 deaths from cancer, 623 deaths from respiratory disease, and 1,305 other-cause deaths. We observed non-linear inverse associations for all-cause, cancer, respiratory disease, and other-cause mortality (P-non-linearity <0.01) and approximately linear inverse associations for CVD mortality (P-non-linearity = 0.074). Among CVD patients with vitamin D deficiency, per 10 nmol/L increment in serum 25(OH)D concentrations was associated with an 12% reduced risk for all-cause mortality and 9% reduced risk for CVD mortality.

Conclusion: Among patients with existing CVD, increasing levels in serum 25(OH)D were independently associated with a decreased risk of all-cause and cause-specific mortality. These findings suggest that elevated serum 25(OH)D concentration benefits CVD patients with vitamin D deficiency.

Vitamin D deficiency in elderly: Risk factors and drugs impact on vitamin D status

Introduction:

Vitamin D (VD) deficiency is a major public health problem worldwide. In spite of its high prevalence, particularly among elderly people, VD deficiency is still underestimated by many physicians. Increasingly, VD deficiency is associated with several known geriatric syndromes.

Methods:

The study sample consisted of 125 patients, aged 75 years and older, admitted to the acute geriatric unit. The plausible association between the serum 25-hydroxyvitamin D [25(OH)D] level and patient age, sex, body mass index, renal function, cholecystectomy history, and the prescribed drugs had been investigated. The Fisher's exact test was used to conduct the statistical analysis of data.

Results:

Surprisingly, furosemide treatment was correlated with normal 25(OH)D levels and an increased incidence of secondary hyperparathyroidism. Unlike the other four parameters mentioned above, our data showed that only the patient sex exhibited a significant association with 25(OH)D level as elderly males suffered from a serious VD deficiency as compared to elderly females.

Conclusion:

Old age is an independent risk factor for VD deficiency. The supplementary dose of VD should be precisely defined to achieve the optimal serum 25(OH)D level in elderly people. The definition of the normal serum 25(OH)D threshold in elderly furosemide-treated patients is worth of further studies.

Cardiac Involvement in Autosomal Dominant Polycystic Kidney Disease

Cardiovascular disorders are the main complication in autosomal dominant polycystic kidney disease (ADPKD). contributing to both morbidity and mortality. This review considers clinical studies unveiling cardiovascular features in patients with ADPKD. Additionally, it focuses on basic science studies addressing the dysfunction of the polycystin proteins located in the cardiovascular system as a contributing factor to cardiovascular abnormalities. In particular, the effects of polycystin proteins’ deficiency on the cardiomyocyte function have been considered.

Vitamin D and cardiovascular health

The principal source of vitamin D in humans is its biosynthesis in the skin through a chemical reaction dependent on sun exposure. In lesser amounts, the vitamin can be obtained from the diet, mostly from fatty fish, fish liver oil and mushrooms. Individuals with vitamin D deficiency, defined as a serum level of 25 hydroxyvitamin D < 20 ng/dl, should be supplemented. Vitamin D deficiency is a prevalent global problem caused mainly by low exposure to sunlight. The main role of 1,25 dihydroxyvitamin D is the maintenance of calcium and phosphorus homeostasis. However, vitamin D receptors are found in most human cells and tissues, indicating many extra-skeletal effects of the vitamin, particularly in the immune and cardiovascular (CV) systems. Vitamin D regulates blood pressure by acting on endothelial cells and smooth muscle cells. Its deficiency has been associated with various CV risk factors and appears to be linked to a higher mortality and incidence of CV disease (CVD). Several mechanisms have been proposed relating vitamin D deficiency to CV risk factors such as renin-angiotensin-aldosterone system activation, abnormal nitric oxide regulation, oxidative stress or altered inflammatory pathways. However, in the latest randomized controlled trials no benefits of vitamin D supplementation for CVD have been confirmed. Although more work is needed to establish the protective role of vitamin D in this setting, according to current evidences vitamin D supplements should not be recommended for CVD prevention.

Calcitriol ameliorated autonomic dysfunction and hypertension by down-regulating inflammation and oxidative stress in the paraventricular nucleus of SHR

The hypothalamic paraventricular nucleus (PVN) plays crucial roles in central cardiovascular regulation. Increasing evidence in humans and rodents shows that vitamin D intake is important for achieving optimal cardiovascular function. The purpose of this study was to investigate whether calcitriol, an active form of vitamin D, improves autonomic and cardiovascular function in hypertensive rats and whether PVN oxidative stress and inflammation are involved in these beneficial effects. Male spontaneously hypertensive rats (SHR) and normotensive control Wistar Kyoto (WKY) rats were treated with either calcitriol (40 ng/day) or vehicle (0.11 μL/h) through chronic PVN infusion for 4 weeks. Blood pressure and heart rate were recorded continuously by radiotelemetry. PVN tissue, heart and plasma were collected for molecular and histological analysis. Compared to WKY rats, SHR exhibited increased systolic blood pressure, sympathetic drive, and cardiac hypertrophy and remodeling. These were associated with higher mRNA and protein expression levels of high mobility box 1 (HMGB1), receptor for advanced glycation end products (RAGE), toll-like receptor 4 (TLR4), nuclear factor-kappa B (NF-κB), proinflammatory cytokines, NADPH oxidase subunit in the PVN. In addition, increased norepinephrine in plasma, elevated reactive oxygen species levels and activation of microglia in the PVN were also observed in SHR. Chronic calcitriol treatment ameliorated these changes but not in WKY rats. Our results demonstrate that chronic infusion of calcitriol in the PVN ameliorates hypertensive responses, sympathoexcitation and retains cardiovascular function in SHR. Reduced inflammation and oxidative stress within the PVN are involved in these calcitriol-induced effects.

Working Toward an Improved Understanding of Chronic Cardiorenal Syndrome Type 4

Chronic diseases of the heart and of the kidneys commonly coexist in individuals. Certainly combined and persistent heart and kidney failure can arise from a common pathologic insult, for example, as a consequence of poorly controlled hypertension or of severe diffuse arterial disease. However, strong evidence is emerging to suggest that cross talk exists between the heart and the kidney. Independent processes are set in motion when kidney function is chronically diminished, and these processes can have distinct adverse effects on the heart. The complex chronic heart condition that results from chronic kidney disease (CKD) has been termed cardiorenal syndrome type 4. This review will include an updated description of the cardiac morphology in patients who have CKD, an overview of the most likely CKD-sourced culprits for these cardiac changes, and the potential therapeutic strategies to limit cardiac complications in patients who have CKD.

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.

Calcitriol Prevents Cardiovascular Repercussions in Puromycin Aminonucleoside-Induced Nephrotic Syndrome

Puromycin aminonucleoside-induced nephrotic syndrome (PAN-NS) is characterized by cardiac remodeling and increased local inflammatory activity. Patients with NS and animal models of NS have vitamin D3 deficiency. The aim of the present study was to evaluate the influence of calcitriol on cardiac remodeling and local inflammatory state in PAN-NS rat model. Male Sprague-Dawley rats were injected with PAN or vehicle on day 0. PAN and control rats were divided into two subgroups for the administration of calcitriol (PAN-D and Ct-D groups) or the vehicle (PAN-V and Ct-V groups) during 21 days. On day 21, the renal function, metabolic balance, calcitriol and FGF-23 plasma levels, prohypertrophy and proinflammatory markers (ET-1, TGF-β1, TNF-α, and IL-1β), and calcium signaling molecules (PLB and SERCA-2a) were evaluated. Twenty-one days after injection, PAN-V group presented cardiac hypertrophy and a modulation of proinflammatory markers local expression. Calcitriol treatment of PAN rats prevented cardiac hypertrophy and was associated with marked reduction in the cardiac expression levels of proinflammatory markers. Our results suggest that vitamin D3 deficiency in PAN-NS may contribute to cardiac remodeling and to the increase in local inflammatory activity. Calcitriol treatment prevents both cardiac repercussions and local inflammatory processes in PAN-NS.

Vitamin D, reactive oxygen species and calcium signalling in ageing and disease

Vitamin D is a hormone that maintains healthy cells. It functions by regulating the low resting levels of cell signalling components such as Ca(2+) and reactive oxygen species (ROS). Its role in maintaining phenotypic stability of these signalling pathways depends on the ability of vitamin D to control the expression of those components that act to reduce the levels of both Ca(2+) and ROS. This regulatory role of vitamin D is supported by both Klotho and Nrf2. A decline in the vitamin D/Klotho/Nrf2 regulatory network may enhance the ageing process, and this is well illustrated by the age-related decline in cognition in rats that can be reversed by administering vitamin D. A deficiency in vitamin D has also been linked to two of the major diseases in man: heart disease and Alzheimer's disease (AD). In cardiac cells, this deficiency alters the Ca(2+) transients to activate the gene transcriptional events leading to cardiac hypertrophy and the failing heart. In the case of AD, it is argued that vitamin D deficiency results in the Ca(2+) landscape that initiates amyloid formation, which then elevates the resting level of Ca(2+) to drive the memory loss that progresses to neuronal cell death and dementia.This article is part of the themed issue 'Evolution brings Ca(2+) and ATP together to control life and death'.

Vitamin D and Cardiovascular Disease: Controversy Unresolved

Vitamin D deficiency is typically caused by inadequate cutaneous synthesis secondary to decreased exposure to sunlight. Serum levels of 25-hydroxyvitamin D l <20 ng/ml are diagnostic of vitamin D deficiency. Vitamin D has various cardiovascular pleiotropic effects by activating its nuclear receptor in cardiomyocytes and vascular endothelial cells and by regulating the renin-angiotensin-aldosterone system, adiposity, energy expenditure, and pancreatic cell activity. In humans, vitamin D deficiency is associated with the following: vascular dysfunction; arterial stiffening; left ventricular hypertrophy; and worsened metrics of diabetes, hypertension, and hyperlipidemia. It is also linked with worse cardiovascular morbidity and mortality. However, meta-analyses of vitamin D supplementation trials have failed to show clear improvements in blood pressure, insulin sensitivity, or lipid parameters, thus suggesting that the link between vitamin D deficiency and cardiovascular disease may be an epiphenomenon. Ongoing larger randomized trials will clarify whether monitoring and supplementation of vitamin D play roles in cardiovascular protection.

Effect of vitamin D on isoprenaline-induced myocardial infarction in rats: possible role of peroxisome proliferator-activated receptor-γ

Infarct-like lesion induced by isoprenaline is a well-known model to study myocardial infarction (MI). Vitamin D has been shown to have anti-inflammatory and antioxidant effects. Recent studies highlighted cross talk between vitamin D and peroxisome proliferator-activated receptor gamma (PPAR-γ). The present study was designed to investigate the effect of pretreatment with vitamin D on the isoprenaline-induced infarct-like lesion in rats and the role of PPAR-γ as a novel mechanism in vitamin-D-mediated cardioprotective effect. Markers chosen to assess cardiac damage included serum level of creatine kinase (CK), lactate dehydrogenase (LDH), tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6). Cardiac contents of malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GSH) were also assessed. Furthermore, ECG monitoring and measurement of injury extension were carried out. Isoprenaline increased the level of cardiac enzymes, as well as inflammatory and oxidative stress biomarkers. In addition, it produced ST-segment elevation. Pretreatment with vitamin D significantly improved previous parameters. The prior treatment with bisphenol A diglycidyl ether (BADGE), a PPAR-γ antagonist, significantly attenuated the protective effect of vitamin D. In conclusion, vitamin D can be demonstrated as a promising cardioprotective agent in MI and PPAR-γ significantly contributes toward vitamin-D-mediated protection.

Paricalcitol Attenuates Cardiac Fibrosis and Expression of Endothelial Cell Transition Markers in Isoproterenol-Induced Cardiomyopathic Rats

OBJECTIVES

Acute cardiomyopathy is a health problem worldwide. Few studies have shown an association between acute cardiomyopathy and low vitamin D status. Paricalcitol, a vitamin D receptor activator, clinically benefits patients with advanced kidney disease. The effect of paricalcitol supplement on cardiac remodeling in cardiomyopathic rats is unknown. This experimental study investigated the effect of paricalcitol in rats with cardiomyopathy induced by isoproterenol.

DESIGN

Prospective, randomized, controlled experimental study.

SETTING

Hospital-affiliated animal research institution.

SUBJECTS

Eight-week-old male Wistar-Kyoto rats.

INTERVENTIONS

Male Wistar-Kyoto rats were first injected intraperitoneally with isoproterenol to create a rat model of acute cardiomyopathy. Then paricalcitol was administered intraperitoneally to isoproterenol-injected rats at a dosage of 200 ng three times a week for 3 weeks. Relevant cardiomyopathy-related variables were measured regularly in three groups of rats, controls, isoproterenol, and isoproterenol plus paricalcitol. Rat hearts were obtained for evaluation of cardiac fibrosis using Masson trichrome staining and commercially available software, and evaluation of cell transition using immunofluorescence staining analysis.

MEASUREMENTS AND MAIN RESULTS

Isoproterenol infusions generated significant cardiac fibrosis (p < 0.001). Subsequent paricalcitol treatment attenuated the isoproterenol-induced cardiac fibrosis (p = 0.006). Fluorescence showed colocalization of endothelial and fibroblast cell markers (cluster differentiation 31 and α-smooth muscle actin, respectively) in the isoproterenol-treated hearts. Paricalcitol injections attenuated the isoproterenol-induced fluorescence intensity of two cell markers (p < 0.01).

CONCLUSIONS

Paricalcitol injections may ameliorate isoproterenol-induced cardiac fibrosis possibly through regulating cell transition.

Both high and low plasma levels of 25-hydroxy vitamin D increase blood pressure in a normal rat model

The lower threshold plasma 25-hydroxy vitamin D (25(OH)D) level for optimal cardiovascular health is unclear, whereas the toxicity threshold is less clear. The aim of this study was to examine the cardiovascular-vitamin D dose-response curve in a normal rat model. Doses of cholecalciferol ranged from deficiency to toxic levels (equivalent to human doses of 0, 0·015, 0·25 and 3·75mg/d) for 4 weeks, and then cardiovascular health was examined using blood pressure telemetry and high-resolution ultrasound in normal male rats (n 16/group, 64 rats total). After 1 month, only the 0·25mg/d group had plasma 25(OH)D that was within current recommended range (100-125 nmol/l), and all groups failed to change plasma Ca or phosphate. Systolic blood pressure increased significantly (10-15 mmHg) in the rat groups with plasma 25(OH)D levels at both 30 and 561 nmol/l (groups fed 0 and 3·75mg/d) compared with the group fed the equivalent to 0·015mg/d (43 nmol/l 25(OH)D). Although not significant, the group fed the equivalent to 0·25mg/d (108 nmol/l 25(OH)D) also showed a 10 mmHg increase in systolic blood pressure. Carotid artery diameter was significantly smaller and wall thickness was larger, leading to higher peak carotid systolic blood velocity in these two groups. Despite these vascular changes, cardiac function did not differ among treatment groups. The key finding in this study is that arterial stiffness and systolic blood pressure both showed a U-shaped dose-response for vitamin D, with lowest values (best cardiovascular health) observed when plasma 25(OH)D levels were 43 nmol/l in normal male rats.

Is Vitamin D Deficiency Associated With Heart Failure? A Review of Current Evidence

An estimated 1 billion people worldwide have deficient or insufficient levels of vitamin D. Even more alarming is the association of vitamin D deficiency with many types of diseases, particularly heart failure (HF). Hypovitaminosis D has been observed to be highly prevalent in the HF community with rates varying from approximately 80% to 95%. Higher rates of deficiency have been linked to winter months, in patients with protracted decompensated HF, darker skin pigmentation, and higher New York Heart Association (NYHA) classes. In fact, some data suggest vitamin D deficiency may even be an independent predictor of mortality in patients with HF. Traditionally obtained through UV exposure and activated in the liver and then the kidneys, vitamin D is classified as a vitamin but functions as a steroid hormone. The hormone acts through the vitamin D receptor (VDR), which is expressed in vascular smooth muscle cells, renal juxtaglomerular cells, and most interestingly, cardiac myocytes. Studies have shown that the association between vitamin D deficiency and HF often manifests in the structural components of cardiac myocytes and/or through alterations of the neurohormonal cascade. In addition, vitamin D may also act rapidly through intracellular nongenomic receptors that alter cardiac contractility. Unfortunately, prospective vitamin D supplementation trials show mixed results. In rat models, successful correction of deficiency was associated with reductions in ventricular hypertrophy. In humans, however, echocardiographic dimensions did not change significantly. These results bring into questions whether vitamin D is a risk factor for HF, a marker of HF disease severity, or has a true pathologic role. This article provides a thorough review of vitamin D deficiency etiology, prevalence, and possible pathophysiologic role in HF. Furthermore, we carefully review prospective trials on vitamin D therapy in HF. We believe more trials on vitamin D therapy in HF need to be conducted before any conclusions can be drawn.

1,25-Dihydroxyvitamin D and Klotho: A Tale of Two Renal Hormones Coming of Age

1,25-Dihydroxyvitamin D3 (1,25D) is the renal metabolite of vitamin D that signals through binding to the nuclear vitamin D receptor (VDR). The ligand-receptor complex transcriptionally regulates genes encoding factors stimulating calcium and phosphate absorption plus bone remodeling, maintaining a skeleton with reduced risk of age-related osteoporotic fractures. 1,25D/VDR signaling exerts feedback control of Ca/PO4 via regulation of FGF23, klotho, and CYP24A1 to prevent age-related, ectopic calcification, fibrosis, and associated pathologies. Vitamin D also elicits xenobiotic detoxification, oxidative stress reduction, neuroprotective functions, antimicrobial defense, immunoregulation, anti-inflammatory/anticancer actions, and cardiovascular benefits. Many of the healthspan advantages conferred by 1,25D are promulgated by its induction of klotho, a renal hormone that is an anti-aging enzyme/coreceptor that protects against skin atrophy, osteopenia, hyperphosphatemia, endothelial dysfunction, cognitive defects, neurodegenerative disorders, and impaired hearing. In addition to the high-affinity 1,25D hormone, low-affinity nutritional VDR ligands including curcumin, polyunsaturated fatty acids, and anthocyanidins initiate VDR signaling, whereas the longevity principles resveratrol and SIRT1 potentiate VDR signaling. 1,25D exerts actions against neural excitotoxicity and induces serotonin mood elevation to support cognitive function and prosocial behavior. Together, 1,25D and klotho maintain the molecular signaling systems that promote growth (p21), development (Wnt), antioxidation (Nrf2/FOXO), and homeostasis (FGF23) in tissues crucial for normal physiology, while simultaneously guarding against malignancy and degeneration. Therefore, liganded-VDR modulates the expression of a "fountain of youth" array of genes, with the klotho target emerging as a major player in the facilitation of health span by delaying the chronic diseases of aging.

Vitamin D: Metabolism, Molecular Mechanism of Action, and Pleiotropic Effects

1,25-Dihydroxvitamin D3 [1,25(OH)2D3] is the hormonally active form of vitamin D. The genomic mechanism of 1,25(OH)2D3 action involves the direct binding of the 1,25(OH)2D3 activated vitamin D receptor/retinoic X receptor (VDR/RXR) heterodimeric complex to specific DNA sequences. Numerous VDR co-regulatory proteins have been identified, and genome-wide studies have shown that the actions of 1,25(OH)2D3 involve regulation of gene activity at a range of locations many kilobases from the transcription start site. The structure of the liganded VDR/RXR complex was recently characterized using cryoelectron microscopy, X-ray scattering, and hydrogen deuterium exchange. These recent technological advances will result in a more complete understanding of VDR coactivator interactions, thus facilitating cell and gene specific clinical applications. Although the identification of mechanisms mediating VDR-regulated transcription has been one focus of recent research in the field, other topics of fundamental importance include the identification and functional significance of proteins involved in the metabolism of vitamin D. CYP2R1 has been identified as the most important 25-hydroxylase, and a critical role for CYP24A1 in humans was noted in studies showing that inactivating mutations in CYP24A1 are a probable cause of idiopathic infantile hypercalcemia. In addition, studies using knockout and transgenic mice have provided new insight on the physiological role of vitamin D in classical target tissues as well as evidence of extraskeletal effects of 1,25(OH)2D3 including inhibition of cancer progression, effects on the cardiovascular system, and immunomodulatory effects in certain autoimmune diseases. Some of the mechanistic findings in mouse models have also been observed in humans. The identification of similar pathways in humans could lead to the development of new therapies to prevent and treat disease.

Paricalcitol modulates ACE2 shedding and renal ADAM17 in NOD mice beyond proteinuria

Circulating and renal activity of angiotensin-converting enzyme 2 (ACE2) is increased in non-obese diabetic (NOD) mice. Because paricalcitol has been reported to protect against diabetic nephropathy, we investigated the role of paricalcitol in modulating ACE2 in these mice. In addition, renal ADAM17, a metalloprotease implied in ACE2 shedding, was assessed. NOD female and non-diabetic control mice were studied for 21 days after diabetes onset and divided into various treatment groups. Diabetic animals received either vehicle; 0.4 or 0.8 μg/kg paricalcitol, aliskiren, or a combination of paricalcitol and aliskiren. We then studied the effect of paricalcitol on ACE2 expression in proximal tubular epithelial cells. Paricalcitol alone or in combination with aliskiren resulted in significantly reduced circulating ACE2 activity in NOD mice but there were no changes in urinary albumin excretion. Serum renin activity was significantly decreased in mice that received aliskiren but no effect was found when paricalcitol was used alone. Renal content of ADAM17 was significantly decreased in animals that received a high dose of paricalcitol. Renal and circulating oxidative stress (quantified by plasma H2O2 levels and immunolocalization of nitrotyrosine) were reduced in high-dose paricalcitol-treated mice compared with non-treated diabetic mice. In culture, paricalcitol incubation resulted in a significant increase in ACE2 expression compared with nontreated cells. In NOD mice with type 1 diabetes, paricalcitol modulates ACE2 activity, ADAM17, and oxidative stress renal content independently from the glycemic profile and urinary albumin excretion. In tubular cells, paricalcitol may modulate ACE2 by blocking its shedding. In the early stage of diabetic nephropathy, paricalcitol treatment counterbalances the effect of diabetes on circulating ACE2 activity. Our results suggest that additional use of paricalcitol may be beneficial in treating patients with diabetes under standard therapeutic strategies.

Vitamin D cell signalling in health and disease

Vitamin D deficiency has been linked to many human diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), hypertension and cardiovascular disease. A Vitamin D phenotypic stability hypothesis, which is developed in this review, attempts to describe how this vital hormone acts to maintain healthy cellular functions. This role of Vitamin D as a guardian of phenotypic stability seems to depend on its ability to maintain the redox and Ca(2+) signalling systems. It is argued that its primary action is to maintain the expression of those signalling components responsible for stabilizing the low resting state of these two signalling pathways. This phenotypic stability role is facilitated through the ability of vitamin D to increase the expression of both Nrf2 and the anti-ageing protein Klotho, which are also major regulators of Ca(2+) and redox signalling. A decline in Vitamin D levels will lead to a decline in the stability of this regulatory signalling network and may account for why so many of the major diseases in man, which have been linked to vitamin D deficiency, are associated with a dysregulation in both ROS and Ca(2+) signalling.

Vitamin D plasma levels and in-hospital and 1-year outcomes in acute coronary syndromes: a prospective study

Deficiency in 25-hydroxyvitamin D (25[OH]D), the main circulating form of vitamin D in blood, could be involved in the pathogenesis of acute coronary syndromes (ACS). To date, however, the possible prognostic relevance of 25 (OH)D deficiency in ACS patients remains poorly defined. The purpose of this prospective study was to assess the association between 25 (OH)D levels, at hospital admission, with in-hospital and 1-year morbidity and mortality in an unselected cohort of ACS patients.We measured 25 (OH)D in 814 ACS patients at hospital presentation. Vitamin D serum levels >30 ng/mL were considered as normal; levels between 29 and 21 ng/mL were classified as insufficiency, and levels < 20 ng/mL as deficiency. In-hospital and 1-year outcomes were evaluated according to 25 (OH)D level quartiles, using the lowest quartile as a reference.Ninety-three (11%) patients had normal 25 (OH)D levels, whereas 155 (19%) and 566 (70%) had vitamin D insufficiency and deficiency, respectively. The median 25 (OH)D level was similar in ST-elevation myocardial infarction (STEMI) and non-ST-elevation myocardial infarction (NSTEMI) patients (14.1 [IQR 9.0-21.9] ng/mL and 14.05 [IQR 9.1-22.05] ng/mL, respectively; P = .88). The lowest quartile of 25 (OH)D was associated with a higher risk for several in-hospital complications, including mortality. At a median follow-up of 366 (IQR 364-379) days, the lowest quartile of 25 (OH)D, after adjustment for the main confounding factors, remained significantly associated to 1-year mortality (P < .01). Similar results were obtained when STEMI and NSTEMI patients were considered separately.In ACS patients, severe vitamin D deficiency is independently associated with poor in-hospital and 1-year outcomes. Whether low vitamin D levels represent a risk marker or a risk factor in ACS remains to be elucidated.

Beneficial effects of calcitriol on hypertension, glucose intolerance, impairment of endothelium-dependent vascular relaxation, and visceral adiposity in fructose-fed hypertensive rats

Besides regulating calcium homeostasis, the effects of vitamin D on vascular tone and metabolic disturbances remain scarce in the literature despite an increase intake with high-fructose corn syrup worldwide. We investigated the effects of calcitriol, an active form of vitamin D, on vascular relaxation, glucose tolerance, and visceral fat pads in fructose-fed rats. Male Wistar-Kyoto rats were divided into 4 groups (n = 6 per group). Group Con: standard chow diet for 8 weeks; Group Fru: high-fructose diet (60% fructose) for 8 weeks; Group Fru-HVD: high-fructose diet as Group Fru, high-dose calcitriol treatment (20 ng / 100 g body weight per day) 4 weeks after the beginning of fructose feeding; and Group Fru-LVD: high-fructose diet as Group Fru, low-dose calcitriol treatment (10 ng / 100 g body weight per day) 4 weeks after the beginning of fructose feeding. Systolic blood pressure was measured twice a week by the tail-cuff method. Blood was examined for serum ionized calcium, phosphate, creatinine, glucose, triglycerides, and total cholesterol. Intra-peritoneal glucose intolerance test, aortic vascular reactivity, the weight of visceral fat pads, adipose size, and adipose angiotensin II levels were analyzed at the end of the study. The results showed that the fructose-fed rats significantly developed hypertension, impaired glucose tolerance, heavier weight and larger adipose size of visceral fat pads, and raised adipose angiotensin II expressions compared with the control rats. High- and low-dose calcitriol reduced modestly systolic blood pressure, increased endothelium-dependent aortic relaxation, ameliorated glucose intolerance, reduced the weight and adipose size of visceral fat pads, and lowered adipose angiotensin II expressions in the fructose-fed rats. However, high-dose calcitriol treatment mildly increased serum ionized calcium levels (1.44 ± 0.05 mmol/L). These results suggest a protective role of calcitriol treatment on endothelial function, glucose tolerance, and visceral adiposity in fructose-fed rats.

Vitamin D deficiency plays an important role in cardiac disease and affects patient outcome: Still a myth or a fact that needs exploration?

There is increasing evidence that a low vitamin D status may be an important and hitherto neglected factor of cardiovascular disease. This review is an overview of the current body of literature, and presents evidence of the mechanisms through which vitamin D deficiency affects the cardiovascular system in general and the heart in particular. Available data indicate that the majority of congestive heart failure patients have 25-hydroxyvitamin D deficiency. Furthermore, the low serum 25-hydroxyvitamin D level has a higher impact on hypertension, coronary artery disease an on the occurrence of relevant cardiac events. A serum 25-hydroxyvitamin D level below 75 nmol/l (30 ng/l) is generally regarded as vitamin D insufficiency in both adults and children, while a level below 50 nmol/l (20 ng/l) is considered deficiency. Levels below 50 nmol/l (20 ng/l) are linked independently to cardiovascular morbidity and mortality.

Vitamin D deficiency and atrial fibrillation

Vitamin D deficiency has been linked with hypertension, coronary artery disease, and stroke, but there is no consensus regarding the possible association between vitamin D deficiency and atrial fibrillation (AF). Vitamin D negatively regulates the renin-angiotensin-aldosterone-system (RAAS), mediates calcium homeostasis, binds to vitamin D receptors on cardiac myocytes, and has antioxidant properties that may reduce levels of reactive oxygen species (ROS) in the atria, which contribute to inflammation and proarrhythmic substrate formation. As vitamin D status is a readily modifiable risk factor this association has potential clinical implications. An extensive search of the literature identified six studies that specifically investigated vitamin D status and AF. Results were equivocal with three studies identifying a positive association between vitamin D deficiency and AF, whilst two studies suggested there may be no association. Additionally, one study indicated that elevated vitamin D levels are associated with AF. Whilst the weight of the evidence suggests that there may be an association between vitamin D deficiency and AF, incomparable study designs and methodological limitations hinder interpretation of the current body of evidence. Further work taking into account considerations raised within this paper is required to better understand the relationship between vitamin D status and AF.

Klotho and phosphate are modulators of pathologic uremic cardiac remodeling

Cardiac dysfunction in CKD is characterized by aberrant cardiac remodeling with hypertrophy and fibrosis. CKD is a state of severe systemic Klotho deficiency, and restoration of Klotho attenuates vascular calcification associated with CKD. We examined the role of Klotho in cardiac remodeling in models of Klotho deficiency-genetic Klotho hypomorphism, high dietary phosphate intake, aging, and CKD. Klotho-deficient mice exhibited cardiac dysfunction and hypertrophy before 12 weeks of age followed by fibrosis. In wild-type mice, the induction of CKD led to severe cardiovascular changes not observed in control mice. Notably, non-CKD mice fed a high-phosphate diet had lower Klotho levels and greatly accelerated cardiac remodeling associated with normal aging compared with those on a normal diet. Chronic elevation of circulating Klotho because of global overexpression alleviated the cardiac remodeling induced by either high-phosphate diet or CKD. Regardless of the cause of Klotho deficiency, the extent of cardiac hypertrophy and fibrosis correlated tightly with plasma phosphate concentration and inversely with plasma Klotho concentration, even when adjusted for all other covariables. High-fibroblast growth factor-23 concentration positively correlated with cardiac remodeling in a Klotho-deficient state but not a Klotho-replete state. In vitro, Klotho inhibited TGF-β1-, angiotensin II-, or high phosphate-induced fibrosis and abolished TGF-β1- or angiotensin II-induced hypertrophy of cardiomyocytes. In conclusion, Klotho deficiency is a novel intermediate mediator of pathologic cardiac remodeling, and fibroblast growth factor-23 may contribute to cardiac remodeling in concert with Klotho deficiency in CKD, phosphotoxicity, and aging.

Cardiac metabolism, inflammation, and peroxisome proliferator-activated receptors modulated by 1,25-dihydroxyvitamin D3 in diabetic rats

BACKGROUND

High free fatty acid with reduced glucose utilization in diabetes mellitus (DM) impairs cardiac function. Peroxisome proliferator-activated receptors (PPARs) modulate myocardial lipid and glucose homeostasis. The active 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) regulates oxidative stress and inflammation, which may play a key role in the modulation of PPARs. The aim of this study was to investigate whether 1,25(OH)2D3 can modulate the cardiac PPARs and fatty acid metabolism.

METHODS

Electrocardiogram, echocardiogram, and Western blot analysis were used to evaluate cardiac fatty acid metabolism, inflammation, and PPAR isoform expression in Wistar-Kyoto (WKY) rats, DM rats, and DM rats treated with 1,25(OH)2D3.

RESULTS

Compared to healthy rats, DM and 1,25(OH)2D3-treated DM rats had lower body weight. DM rats had larger left ventricular end-diastolic diameter, and longer QT interval than healthy or 1,25(OH)2D3-treated DM rats. Moreover, compared to healthy or 1,25(OH)2D3-treated DM rats, DM rats had fewer cardiac PPAR-α and PPAR-δ protein expressions, but had increased cardiac PPAR-γ protein levels, tumor necrosis factor-α, interleukin-6, 5' adenosine monophosphate-activated protein kinaseα2, phosphorylated acetyl CoA carboxylase, carnitine palmitoyltransferase 1, PPAR-γ coactivator 1-α, cluster of differentiation 36, and diacylglycerol acyltransferase 2 protein expressions.

CONCLUSIONS

1,25(OH)2D3 significantly changed the cardiac function and fatty acid regulations in DM hearts, which may be caused by its regulations on cardiac PPARs and proinflammatory cytokines.

Vitamin D in heart failure

Evidence linking vitamin D to cardiovascular (CV) health has accumulated in recent years: numerous epidemiologic studies report deficiency as a significant CV risk factor, and rodent models suggest that active vitamin D can modulate critical remodeling processes, including cardiac hypertrophy and extracellular matrix remodeling. The presence of vitamin D signaling machinery within the human heart implies a direct role for this hormone in cardiac physiology and may explain associations between vitamin D status and CV outcomes. Heart failure (HF) represents a growing social and economic burden worldwide. Myocardial remodeling is central to HF development, and in the context of emerging evidence supporting mechanistic involvement of vitamin D, this review provides critical appraisal of scientific literature related to the role of vitamin D in CV disease, including data from epidemiologic and supplementation studies, as well as novel findings from animal models and in vitro work. Although associative data linking vitamin D and CV outcomes and evidence supporting a role for vitamin D in relevant pathogenic processes are both substantial, there are limited mechanistic data to indicate vitamin D supplementation as a viable therapeutic adjunct for the prevention of HF development following myocardial injury.

Vitamin D and the heart

Vitamin D receptors (VDR) are found in cells throughout the cardiovascular system. A variety of experimental studies indicate that the liganded VDR may play an important role in controlling cardiac hypertrophy and fibrosis, regulating blood pressure, and suppressing the development of atherosclerosis. Some, but not all, observational studies in humans provide support for these experimental findings, raising the possibility that vitamin D or its analogs might prove useful therapeutically in the prevention or treatment of cardiovascular disease.

Liganded vitamin D receptor displays anti-hypertrophic activity in the murine heart

Vitamin D and its analogs have been suggested to have palliative effects in the cardiovascular system. We have examined the effects of co-administration of the vitamin D receptor agonist, paricalcitol, on the hypertension, cardiac hypertrophy and interstitial fibrosis produced by chronic angiotensin II (AII) infusion. Administration of AII (800ng/kg/min) over a 14-day period resulted in increased blood pressure, myocyte hypertrophy, activation of the hypertrophic fetal gene program (atrial natriuretic peptide, B-type natriuretic peptide and alpha skeletal actin gene expression), increased expression of the pro-hypertrophic modulatory calcineurin inhibitor protein 1 (MCIP 1), and increased fibrosis with augmented procollagen 1 and 3 gene expression. In each case co-administration of paricalcitol (300ng/kg intraperitoneally every 48h) at least partially reversed the AII-dependent effect. These studies demonstrate that the liganded vitamin D receptor possesses potent anti-hypertrophic activity in this non-renin-dependent model of cardiac hypertrophy. The anti-hypertrophic activity appears to be at least partially intrinsic to the cardiac myocyte and may involve suppression of the MCIP 1 protein. This article is part of a Special Issue entitled 'Vitamin D Workshop'.

John Sutton M, Wolf M, Feldman H, Reese P, Anderson C, Townsend R, Deo R, Lo J, Gadegbeku C, Carlow D, Sulik MJ, Leonard MB. FGF23 modifies the relationship between vitamin D and cardiac remodeling

BACKGROUND

There is growing evidence to support an important role for vitamin D and related hormones, parathyroid hormone and fibroblast growth factor 23 (FGF23), on cardiac remodeling in chronic kidney disease. Our objective was to determine the relationships between vitamin D and cardiac remodeling in chronic kidney disease and the effects of parathyroid hormone and FGF23 on these associations.

METHODS AND RESULTS

In 1431 participants from the Chronic Renal Insufficiency Cohort study, we measured 25-hydroxyvitamin D (25(OH)D), 1,25-dihydroxyvitamin D (1,25(OH)2D), FGF23, and parathyroid hormone and performed quantitative echocardiography. Using linear regression methods, we determined significant negative interactions between 25(OH)D and FGF23 on left ventricular (LV) mass (P=0.016), end-diastolic volume (P=0.029), and end-systolic volumes (P=0.021). In participants with an FGF23 level greater than the median of 123.5 RU/mL, each doubling of 25(OH)D was associated with a 2.5% (95% confidence interval, -4.8, -0.2) lower LV mass. This association was less pronounced with FGF23 levels less than the median (0.4%; 95% confidence interval, -1.9, 2.7). Conversely, in participants with deficient 25(OH)D levels <20 ng/mL, each doubling of FGF23 was associated with a 3.4% (95% confidence interval, 1.2, 5.6) greater LV mass compared with only a 1.6% (95% confidence interval, -0.2, 3.5) difference in participants with sufficient 25(OH)D. Similar findings were observed with 25(OH)D and volumes (P<0.05), and 1,25(OH)2D and LV mass and volumes (P<0.005). There was no effect modification by parathyroid hormone.

CONCLUSIONS

We identified significant interactions among 25(OH)D, 1,25(OH)2D, and FGF23 on cardiac remodeling. Increased LV mass and cavity dilatation were observed with low 25(OH)D and high FGF23. Our findings suggest that consideration of both hormones is crucial to understanding the role of either in cardiac remodeling, and may have important therapeutic implications.

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.

Mineral metabolism abnormalities and vitamin D receptor activation in cardiorenal syndromes

Over the last decade, it has become increasingly clear that the cardiovascular and renal systems are interdependent. Primary disorders of either system have been shown to disturb the other system. As a result, a class of cardiorenal syndromes (CRS) has been identified wherein a vicious cycle is established as an acute/chronic dysfunction of either the kidney or the heart exacerbates the loss of function in the other organ. Progressive loss of kidney function observed in patients with CRS (mostly types 2 and 4) leads to reduced production of calcitriol (active vitamin D) and an imbalance in calcium and phosphorus levels, which are correlated with increased rates of cardiovascular events and mortality. In addition, hypocalcemia can lead to prolonged and excessive secretion of parathyroid hormone (PTH), eventually leading to development of secondary hyperparathyroidism. Therefore, based on this important mechanism of organ damage, one of the major goals of therapy for patients with CRS is to restore regulatory control of PTH. Although administration of calcitriol increases serum calcium levels and reduces PTH levels, it is also associated with elevated serum levels of calcium-phosphorus product. Therefore, compounds that selectively activate vitamin D receptors, potentially reducing calcium × phosphate toxicity, are likely to enhance cardiorenal protection and provide significant clinical benefit.

Vitamin D deficiency is associated with increased left ventricular mass and diastolic dysfunction in children with chronic kidney disease

Cardiovascular disease currently is the leading cause of morbidity and mortality among patients with chronic kidney disease (CKD). Abnormalities in arterial compliance, increased left ventricular mass, and diastolic dysfunction are some of the recognized cardiovascular complications observed in these patients. This study explored the relationship between various parameters of calcium-phosphorus metabolism including 25-hydroxy vitamin D and cardiovascular structure and function in pediatric patients with CKD. This cross-sectional study was conducted using a cohort of 34 children with CKD who had no history of underlying congenital or structural cardiac disease. Two-dimensional echocardiography was used to measure the left ventricular mass index (LVMI), E/A ratio, E', E/E' ratio, and myocardial performance index (MPI). The augmentation index (AI), derived via radial artery tonometry, was used as an indirect measure of central aortic stiffness. Serum biochemical markers of calcium-phosphorus metabolism were simultaneously measured. Univariate analysis showed that LVMI correlated with 25-hydroxy vitamin D (r = -0.54; p < 0.05), systolic blood pressure (SBP) (r = 0.36; p < 0.05), and AI (r = 0.26; p < 0.05). Serum-intact parathyroid hormone (PTH) levels correlated with the E/E' ratio (r = 0.63; p < 0.05) and E' (r = -0.61; p < 0.05). Multiple regression analysis showed that 25-hydroxy vitamin D and SBP were independent predictors of increased LVMI and that PTH was an independent predictor of diastolic dysfunction. This is the first study investigating pediatric patients with CKD that suggests an etiology of nutritional vitamin D deficiency associated with increased left ventricular mass and diastolic dysfunction. The cardiovascular changes observed are not easily reversible. Hence, early preventive therapy with vitamin D supplementation is advocated.

Relationship between vitamin D status and left ventricular geometry in a healthy population: results from the Baltimore Longitudinal Study of Aging

OBJECTIVES

The effects of vitamin D on the heart have been studied in patients with cardiac disease, but not in healthy persons. We investigated the relation between vitamin D status and left ventricular (LV) structure and function in community-dwelling subjects without heart disease.

DESIGN

The relationship between concentrations of 25-hydroxyvitamin D [25(OH)D], a marker of vitamin D reserve, and LV transthoracic echocardiography measures was analysed in 711 participants in the Baltimore Longitudinal Study of Aging who were without cardiac disease.

RESULTS

Mean 25(OH)D in the study population was 32.3 ± 11.4 ng mL(-1) ; only 15.5% of subjects had moderate or severe vitamin D deficiency [25(OH)D < 20 ng mL(-1) ]. Adjusting for age, body mass index, cardiovascular disease risk factors, physical activity, calcium and parathyroid hormone, 25(OH)D was positively correlated with LV thickness (β 0.095, SE 0.039, P < 0.05) and LV mass index (β 7.5, SE 2.6, P < 0.01). A significant nonlinear relation between 25(OH)D and LV concentric remodelling was observed. LV remodelling was more likely in participants with 25(OH)D levels <30 ng mL(-1) [odds ratio (OR) 1.24; 95% confidence interval (CI) 0.83-1.85] or ≥38 ng mL(-1) (OR 1.73; 95% CI 1.13-2.65), compared with those with 30-37 ng mL(-1) 25(OH)D. Consistently, LV relative wall thickness was significantly lower (P for trend=0.05), and LV diastolic internal diameter index (P for trend<0.05) and end-diastolic volume index (P for trend<0.05) were significantly higher in subjects with 30-37 ng mL(-1) 25(OH)D compared to the rest of the study population. There was a significant interaction between 25(OH)D and hypertension on the risk of LV hypertrophy (P < 0.05).

CONCLUSIONS

In a population-based sample of predominantly vitamin D-sufficient subjects without heart disease, LV geometry was most favourable at intermediate 25(OH)D concentrations.

Impact of vitamin D3 on cardiovascular responses to glucocorticoid excess

Although the cardiovascular system is not a classical target for 1,25-dihydroxyvitamin D3, both cardiac myocytes and vascular smooth muscle cells respond to this hormone. The present study aimed to elucidate the effect of active vitamin D3 on cardiovascular functions in rats exposed to glucocorticoid excess. Adult male Wistar rats were allocated into three groups: control group, dexamethasone (Dex)-treated group receiving Dex (200 μg/kg) subcutaneously for 12 days, and vitamin D3-Dex-treated group receiving 1,25-(OH)2D3 (100 ng/kg) and Dex (200 μg/kg) subcutaneously for 12 days. Rats were subjected to measurement of systolic (SBP), diastolic (DBP), and mean arterial (MAP) blood pressures and heart rate. Rate pressure product (RPP) was calculated. Rats' isolated hearts were perfused in Langendorff preparation and studied for basal activities (heart rate, peaked developed tension, time to peak tension, half relaxation time, and myocardial flow rate) and their responses to isoproterenol infusion. Blood samples were collected for determination of plasma level of nitrite, nitric oxide surrogate. Dex-treated group showed significant increase in SBP, DBP, MAP, and RPP, as well as cardiac hypertrophy and enhancement of basal cardiac performance evidenced by increased heart rate, rapid and increased contractility, and accelerated lusitropy, together with impaired contractile and myocardial flow rate responsiveness to beta-adrenergic activation and depressed inotropic and coronary vascular reserves. Such alterations were accompanied by low plasma nitrite. These changes were markedly improved by vitamin D3 treatment. In conclusion, vitamin D3 is an efficacious modulator of the deleterious cardiovascular responses induced by glucocorticoid excess, probably via accentuation of nitric oxide.

[Hungarian consensus regarding the role of vitamin D in the prevention and treatment of diseases]

The metabolism of vitamin D is unique in the human body and its diverse effects are present in almost every organ. Vitamin D deficiency is one of the most prominent health issues in the civilized world. For the solution of this concern an extensive collaboration is imperative. Recognizing this necessity the most prominent Hungarian medical associations fighting with the effects of vitamin D deficiency worked out a collective consensus on the importance, diagnosis, prevention and suggested therapy of vitamin D deficiency. Along with the clinical guidelines of the different associations, the result of this consensus could serve as guidance for the practicing doctors in the prevention and therapy of vitamin D deficiency. In addition the consensus aims to direct the attention of decision-makers and the general public on the significance of this issue.

Vitamin D levels do not predict cardiovascular events in statin-treated patients with stable coronary disease

BACKGROUND

This post hoc nested case-control analysis of the TNT study was designed to investigate whether baseline vitamin D level is a significant predictor of cardiovascular risk among statin-treated patients and whether changes in vitamin D after treatment with atorvastatin are associated with improved cardiovascular outcomes.

METHODS

A total of 10,001 patients with stable coronary heart disease were randomized to atorvastatin 80 or 10 mg for a median of 4.9 years. This analysis included 1,509 patients (497 with a subsequent cardiovascular event and 1,012 without an event) with vitamin D levels determined at baseline and 1 year. Event rates were analyzed by Cox proportional hazard model by baseline vitamin D levels, with vitamin D as a continuous variable, and with change in vitamin D level as the predictor.

RESULTS

Vitamin D deficiency (<15 ng/mL) or insufficiency (15- <30 ng/mL) was present in 108 (7.2%) of 1,509 and 625 (41.4%) of 1,509 of patients, whereas 46 (3.0%) of 1,509 had elevated vitamin D. There was no relationship between baseline vitamin D levels or change in vitamin D levels and cardiovascular events or mortality. Modeling of events with vitamin D as a continuous variable similarly showed no relationship of vitamin D to events. These findings held true after adjustment for seasonal variations in vitamin D and other confounders.

CONCLUSION

In statin-treated patients with stable coronary heart disease, vitamin D levels did not predict cardiovascular risk. Changes in plasma concentrations of vitamin D after 1 year of treatment made no contribution to the efficacy of atorvastatin therapy.

Effect of alfacalcidol on cardiac function in patients with chronic kidney disease stage 4 and secondary hyperparathyroidism: a pilot study

OBJECTIVE

Left ventricular hypertrophy (LVH) is highly prevalent in chronic kidney disease (CKD) and a risk marker for cardiovascular mortality. It was hypothesized that vitamin D deficiency could play an important role in the pathogenesis of left ventricular hypertrophy and dysfunction in CKD. An open-labelled randomized study was performed comparing the effect of alfacalcidol versus no treatment in patients with CKD 4, secondary hyperparathyroidism and LVH. The primary endpoint was regression of LVH. Secondary endpoints were changes in left ventricular function.

MATERIAL AND METHODS

Twenty-four patients were screened. Of these, 14 had LVH according to the criteria used. Six were randomized to alfacalcidol and seven to no treatment. The patient follow-up was 6 months. Left ventricular mass and function were measured by echocardiography.

RESULTS

Parathyroid hormone decreased by 72% and -3% in the alfacalcidol-treated and non-treated groups, respectively (p < 0.05), while serum Ca(2+) increased by 9% and -1.6%, respectively (p < 0.05), and serum phosphate was unchanged. The left ventricular mass index was unchanged, whereas fractional shortening (20% vs 2%, p < 0.005) and Tei index (36% vs 12%, p < 0.05) increased significantly. Systolic and diastolic blood pressure was unchanged.

CONCLUSION

Short-term treatment with alfacalcidol did not induce regression of LVH; however, left ventricular function became hyperdynamic but less effective in patients with CKD. This could be problematic in the long term.

CARD-024, a vitamin D analog, attenuates the pro-fibrotic response to substrate stiffness in colonic myofibroblasts

Intestinal fibrosis is one of the major complications of Crohn's disease (CD) for which there are no effective pharmacological therapies. Vitamin D deficiency is common in CD, though it is not known whether this is a contributing factor to fibrosis, or simply a consequence of the disease itself. In CD, fibrosis is mediated mainly by activated intestinal myofibroblasts during remodeling of extracellular matrix in response to wound healing. We investigated the effects of CARD-024 (1-alpha-hydroxyvitamin D5), a vitamin D analog with minimal hypercalcemic effects, on the pro-fibrotic response of intestinal myofibroblasts to two fibrogenic stimuli: TGFβ stimulation and culture on a physiologically stiff matrix. TGFβ stimulated a fibrogenic phenotype in Ccd-18co colonic myofibroblasts, characterized by an increase in actin stress fibers and mature focal adhesions, and increased αSMA protein expression, while CARD-024 repressed αSMA protein expression in a dose-dependent manner. Culture of colonic myofibroblasts on physiological high stiffness substrates induced morphological changes with increased actin stress fibers and focal adhesion staining, induction of αSMA protein expression, FAK phosphorylation, induction of fibrogenic genes, and repression of COX-2 and IL-1β. CARD-024 treatment repressed the stiffness-induced morphological features including stellate cell morphology and the maturation of focal adhesions. CARD-024 repressed the stiffness-mediated induction of αSMA protein expression, FAK phosphorylation, and MLCK and ET-1 gene expression. In addition, CARD-024 partially stimulated members of the COX-2/IL-1β inflammatory pathway. In summary, CARD-024 attenuated the pro-fibrotic response of colonic myofibroblasts to high matrix stiffness, suggesting that vitamin D analogs such as CARD-024 may ameliorate intestinal fibrosis.

Vitamin D in relation to myocardial structure and function after eight years of follow-up: the Hoorn study

BACKGROUND AND AIMS

To investigate associations between baseline serum 25-hydroxyvitamin D [25(OH)D] levels and myocardial structure and function after 8 years of follow-up in older Dutch subjects.

METHODS

We included 256 subjects of the Hoorn Study, a population-based cohort. They underwent a standardized 2-dimensional echocardiogram at baseline between 2000 and 2001, and again between 2007 and 2009. We studied the association of 25(OH)D quartiles with echocardiographic measures of the left ventricular mass index (LVMI), left ventricular systolic function and markers of diastolic function using linear regression analyses.

RESULTS

At baseline, subjects had a mean age of 67.4 ± 5.2 years and 41.4% had prior cardiovascular disease (CVD). Low serum 25(OH)D levels were only associated with higher LVMI at 8-year follow-up in subjects without prior CVD and in subjects with low kidney function (median estimated glomerular filtration rate ≤77.5 ml/min/1.73m(2)). The associations attenuated after adjustments for parathyroid hormone (PTH), which was associated with higher LVMI (g/m(2.7)) in subjects with low kidney function (regression coefficient highest quartile 6.3, 95% CI: 0.2, 12.5).

CONCLUSION

This study showed no strong associations of 25(OH)D with myocardial structure and function. However, PTH - a possible modifiable mediator in the relation between 25(OH)D and myocardial structure - was positively associated with LVMI in subjects with low kidney function.