1,25(OH)2D3 suppresses expression and secretion of atrial natriuretic peptide from cardiac myocytes

Untangling the Cooperative Role of Nuclear Receptors in Cardiovascular Physiology and Disease

The heart is the first organ to acquire its physiological function during development, enabling it to supply the organism with oxygen and nutrients. Given this early commitment, cardiomyocytes were traditionally considered transcriptionally stable cells fully committed to contractile function. However, growing evidence suggests that the maintenance of cardiac function in health and disease depends on transcriptional and epigenetic regulation. Several studies have revealed that the complex transcriptional alterations underlying cardiovascular disease (CVD) manifestations such as myocardial infarction and hypertrophy is mediated by cardiac retinoid X receptors (RXR) and their partners. RXRs are members of the nuclear receptor (NR) superfamily of ligand-activated transcription factors and drive essential biological processes such as ion handling, mitochondrial biogenesis, and glucose and lipid metabolism. RXRs are thus attractive molecular targets for the development of effective pharmacological strategies for CVD treatment and prevention. In this review, we summarize current knowledge of RXR partnership biology in cardiac homeostasis and disease, providing an up-to-date view of the molecular mechanisms and cellular pathways that sustain cardiomyocyte physiology.

Baseline Vitamin D Deficiency Decreases the Effectiveness of Statins in HIV-Infected Adults on Antiretroviral Therapy

OBJECTIVE

Vitamin D deficiency is common in HIV. Statins may increase vitamin D, and it is unknown whether vitamin D modifies the effect of statins on cardiovascular disease.

DESIGN

SATURN-HIV was a 96-week, randomized, placebo-controlled trial designed to evaluate the effect of rosuvastatin on immune activation and subclinical vascular disease in HIV-infected adults on antiretroviral therapy. This analysis focuses on the prespecified secondary endpoint 25-hydroxyvitamin D [25(OH)D] concentrations.

METHODS

Mixed effects linear modeling and analysis of variance were used to assess the rosuvastatin effect on plasma 25(OH)D concentrations over time and to determine whether baseline vitamin D modifies the rosuvastatin effect on changes in outcomes over the trial.

RESULTS

Hundred forty-seven adults were randomized (72 to rosuvastatin and 75 to placebo); 78% were men, 68% African American, with a mean age of 45 years. Baseline 25(OH)D concentrations were similar (overall mean 18 ng/mL) with 65% of participants below 20 ng/mL. Changes in 25(OH)D at 96 weeks were small and not significant within- or between-rosuvastatin and placebo groups. There were significant group by vitamin D status interactions for changes in low-density lipoprotein-cholesterol, proportion of patrolling monocytes expressing tissue factor (CD14dimCD16+TF+), lipoprotein-associated phospholipase A2, and common carotid artery intima media thickness at most time points. For each of these outcomes, the beneficial effects of rosuvastatin were either not apparent or attenuated in participants with 25(OH)D <20 ng/mL.

CONCLUSIONS

Although 25(OH)D did not change with rosuvastatin, baseline vitamin D deficiency decreased the effectiveness of rosuvastatin. Vitamin D supplementation may be warranted for deficient patients initiating statin therapy.

Nutritional Deficiency in Patients with Heart Failure

Heart failure (HF) is the main cause of mortality and morbidity in Western countries. Although evidence-based treatments have substantially improved outcomes, prognosis remains poor with high costs for health care systems. In patients with HF, poor dietary behaviors are associated with unsatisfactory quality of life and adverse outcome. The HF guidelines have not recommended a specific nutritional strategy. Despite the role of micronutrient deficiency, it has been extensively studied, and data about the efficacy of supplementation therapy in HF are not supported by large randomized trials and there is limited evidence regarding the outcomes. The aim of the present review is to analyze the state-of-the-art of nutritional deficiencies in HF, focusing on the physiological role and the prognostic impact of micronutrient supplementation.

Which Biomarker is the Best for Predicting Mortality in Incident Peritoneal Dialysis Patients: NT-ProBNP, Cardiac TnT, or hsCRP?: A Prospective Observational Study

Although numerous previous studies have explored various biomarkers for their ability to predict mortality in end-stage renal disease (ESRD) patients, these studies have been limited by retrospective analyses, mostly prevalent dialysis patients, and the measurement of only 1 or 2 biomarkers. This prospective study was aimed to evaluate the association between 3 biomarkers and mortality in incident 335 ESRD patients starting continuous ambulatory peritoneal dialysis (CAPD) in Korea. According to the baseline NT-proBNP, cTnT, and hsCRP levels, the patients were stratified into tertiles, and cardiovascular (CV) and all-cause mortalities were compared. Additionally, time-dependent ROC curves were constructed, and the net reclassification index (NRI) and integrated discrimination improvement (IDI) of the models with various biomarkers were calculated. We found the upper tertile of NT-proBNP was significantly associated with increased risk of both CV and all-cause mortalities. However, the upper tertile of hsCRP was significantly related only to the high risk of all-cause mortality even after adjustment for age, sex, and white blood cell counts. Moreover, NT-proBNP had the highest predictive power for CV mortality, whereas hsCRP was the best prognostic marker for all-cause mortality among these biomarkers. In conclusions, NT-proBNP is a more significant prognostic factor for CV mortality than cTnT and hsCRP, whereas hsCRP is a more significant predictor than NT-proBNP and cTnT for all-cause mortality in incident peritoneal dialysis patients.

Myocardial function in Saudi adolescents with vitamin D deficiency: Tissue Doppler imaging study

Vitamin D deficiency is a common health problem in Saudi Arabia especially in children and adolescents. Many studies have reported the relation between low 25-Hydroxyvitamin D (25(OH)D) levels with cardiovascular diseases risk factors as well as cardiovascular events, including stroke, myocardial infarction, and congestive heart failure. This study was conducted to evaluate the effect of 25(OH)D deficiency on the myocardial function and other echocardiographic variables in adolescent, using tissue Doppler imaging (TDI) and to correlate these parameters with 25(OH)D level. The study included 84 healthy adolescents, consecutively selected from adolescents attending the outpatient clinic of Saad Specialist Hospital, KSA between September 2013 and October 2014. The study population was classified into two groups; vitamin D deficient group with 25(OH)D level less than 20 ng/mL and normal vitamin D (control group) with 25(OH)D equal or more than 30 ng/mL. Both groups were subjected to measuring hemoglobin level, serum albumin, creatinine, total calcium, Phosphorous, intact parathyroid hormone (iPTH), B-type natriuretic peptide (BNP), and 25(OH)D levels. Both conventional and pulsed wave TDI were done for all participants. TDI measurements showed significant higher LV Tei Index and RV Tei index when compared to the control group (0.61 ± 0.11 Vs 0.32 ± 0.05 p < 0.0001), (0.54 ± 0.14 Vs 0.40 ± 0.06 p < 0.0001) respectively. Mitral and tricuspid annular systolic velocities were significantly lower in vitamin D deficient group (6.99 ± 1.92 Vs 10.69 ± 0.31 cm/sec p < 0.0001 and 12.30 ± 2.14 Vs 13.89 ± 0.29 p < 0.0001 respectively). The mitral and tricuspid E/Em ratio was significantly higher in vitamin D deficient group than control group (p < 0.0001, p 0.005) respectively. Left ventricular internal diameter at end-diastole (LVIDd) was significantly higher in vitamin D deficient group (44.72 ± 6.33 Vs 40.36 ± 6.21 p 0.003). Serum 25(OH)D level showed significant negative correlation with LV Tei index (r = −0.668, p < 0.0001), RV Tei index (r = −0.421, p < 0.0001). Vitamin D deficiency is associated with subtle systolic and diastolic myocardial dysfunction in Saudi adolescents. TDI is a useful tool for detecting early changes in the myocardium in this particular group.

The effect of oral vitamin D on serum level of N-terminal pro-B-type natriuretic peptide

BACKGROUND

The risk of cardiovascular disease in dialysis patients is higher than the general population. Vitamin D receptors exist in myocardium inhibit cardiac hypertrophy. N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) is a neurohormone secreted by the heart in response to ventricular mass increase. This study aimed to evaluate the effect of oral vitamin D on serum level of pro-B-type natriuretic peptide (pro-BNP) in peritoneal dialysis patients.

MATERIALS AND METHODS

In a randomized clinical trial, 84 peritoneal dialysis patients (49 males and 35 females) were randomly divided into two groups. The intervention group received 50000 units oral vitamin D per week, for 12 weeks if 25-hydroxy-vitamin D level was <10 ng/ml and for 8 weeks if it was between 10 ng/ml and 30 ng/ml. The control group received placebo. Parathyroid hormone, calcium, phosphor, 25-hydroxy-vitamin D, albumin and NT-pro-BNP were evaluated before and after the study.

RESULTS

The mean serum level of pro-BNP in patients receiving vitamin D and placebo group before the study was 875 pg/ml and 793 pg/ml, respectively. There was 895.9 pg/ml in the intervention group and 736.7 pg/ml in the control group (P = 0.7). Mean serum level of 25(OH) D in patients receiving oral vitamin D and placebo group before the study was 16.9 ng/ml and 31.9 ng/ml, respectively. There was 28.9 ng/ml in the intervention group and 12.9 ng/ml in the control group (P = 0.001). There were no significant differences regarding other indices (Alb, P, Ca, intact parathyroid hormone) between two groups.

CONCLUSION

Vitamin D did not significantly change the serum level of pro-BNP in peritoneal dialysis patients.

Study of vitamin D deficiency prevalence in acute myocardial infarction

BACKGROUND

Deficiency of 25-hydroxy vitamin D [25(OH)D] is a treatable condition that has been associated with coronary artery disease and many of its risk factors. A practical time to assess for 25(OH)D deficiency, and to initiate treatment, is at the time of an acute myocardial infarction(AMI). The prevalence of 25(OH)D deficiency and the characteristics associated with it in patients with acute myocardial infarction are unknown.

METHODS

In this study 25(OH)D was assessed in 314 subjects enrolled in a Sri Jayadeva Institute of Cardiovascular Science and Research(SJICS&R). Patients enrolled from December 1, 2011 to February 28, 2012 had serum samples sent to a centralized laboratory for analysis using the ELECYS assay. Normal 25(OH)D levels are ≥ 30 ng/ml, and patients with levels < 30 and > 20 ng/ml were classified as insufficient and those with levels ≤ 20 ng/ml as deficient. Vitamin D and other baseline characteristics were analyzed with T-test and chi-squared test.

RESULTS

Of the 314 enrolled patents, 212 (67.5%) were 25(OH)D deficient and 50(16%) were insufficient, for a total of 83.5% of patients with abnormally low 25(OH)D levels. No significant heterogeneity was observed among age or gender sub groups but 25(OH)D deficiency was more commonly seen in those with lower socioeconomic status, lower activity levels, diabetes, hypercholesterolemia(LDL), hypertriglyceridemia and in smokers.

CONCLUSION

Vitamin D deficiency is present in most of the patients with acute myocardial infarction and it is associated with many of its risk factors in our study.

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.

The pleiotropic effect of vitamin d

The novel roles of vitamin D were discovered and valued in this century. In addition to the maintenance of calcium and phosphorus balance, vitamin D regulates the function of the kidneys, heart, and immune system. Moreover, its anti-inflammatory, antiapoptotic, and antifibrotic roles have gained considerable attention. Vitamin D is also important for the maintenance of homeostasis by regulation of hormone secretion, cell proliferation, and differentiation. This paper will review these pleiotropic functions of vitamin D.

Association of 25-hydroxyvitamin D deficiency with NT-pro BNP levels in patients with acute myocardial infarction: a cross-sectional analysis

Background

Nutritional vitamin D deficiency is an emerging risk factor for acute myocardial infarction (AMI) and heart failure. The association of 25-hydroxyvitamin D levels with N-terminal pro B-type natriuretic peptide (NT-proBNP), a robust prognostic marker for post-AMI mortality and heart failure, is unknown and could illuminate a potential pathway for adverse outcomes among post-AMI patients with 25-hydroxyvitamin D deficiency.

Methods

In a cross-sectional analysis, we studied 238 AMI patients from 21 U.S. centers to test the association of nutritional vitamin D (25-hydroxyvitamin D [25(OH)D]) deficiency with NT-proBNP levels. Levels of 25(OH)D levels were categorized as normal (≥30 ng/mL), insufficient (>20 - <30 ng/mL), deficient (>10 - ≤20 ng/mL), or severely deficient (≤10 ng/mL).

Results

Low 25(OH)D levels were found in 95.7% of AMI patients. No significant trends for higher mean baseline log NT-proBNP levels in severely deficient (6.9 ± 1.3 pg/mL), deficient (6.9 ± 1.2 pg/mL), and insufficient (6.9 ± 0.9 pg/ml) groups were observed as compared with patients having normal (6.1 ± 1.7 pg/mL) levels, P = 0.17. Findings were similar in the subset of patients who had follow-up NT-proBNP levels drawn at one month. In multivariate regression modeling, after adjusting for multiple covariates, 25(OH)D was not associated with NT-proBNP.

Conclusions

Potential associations between nutritional vitamin D deficiency and prognosis in the setting of AMI are unlikely to be mediated through NT-proBNP pathways. Future studies should examine other mechanisms, such as inflammation and vascular calcification, by which 25(OH)D deficiency could mediate adverse outcomes post-AMI.

Potential for vitamin D receptor agonists in the treatment of cardiovascular disease

Vitamin D(3) is made in the skin and modified in the liver and kidney to form the active metabolite, 1,25-dihydroxyvitamin D(3) (calcitriol). Calcitriol binds to a nuclear receptor, the vitamin D receptor (VDR), and activates VDR to recruit cofactors to form a transcriptional complex that binds to vitamin D response elements in the promoter region of target genes. During the past three decades the field has focused mainly on the role of VDR in the regulation of parathyroid hormone, intestinal calcium/phosphate absorption and bone metabolism; several VDR agonists (VDRAs) have been developed for the treatment of osteoporosis, psoriasis and hyperparathyroidism secondary to chronic kidney disease (CKD). Emerging evidence suggests that VDR plays important roles in modulating cardiovascular, immunological, metabolic and other functions. For example, data from epidemiological, preclinical and clinical studies have shown that vitamin D and/or 25(OH)D deficiency is associated with increased risk for cardiovascular disease (CVD). However, VDRA therapy seems more effective than native vitamin D supplementation in modulating CVD risk factors. In CKD, where decreasing VDR activation persists over the course of the disease and a majority of the patients die of CVD, VDRA therapy was found to provide a survival benefit in both pre-dialysis and dialysis CKD patients. Although VDR plays an important role in regulating cardiovascular function and VDRAs may be potentially useful for treating CVD, at present no VDRA is approved for CVD, and also no serum markers, beside parathyroid hormone in CKD, exist to indicate the efficacy of VDRA in CVD.

Expression of the vitamin d receptor is increased in the hypertrophic heart

The liganded vitamin D receptor (VDR) is thought to play an important role in controlling cardiac function. Specifically, this system has been implicated as playing an antihypertrophic role in the heart. Despite this, studies of VDR in the heart have been limited in number and scope. In the present study, we used a combination of real-time polymerase chain reaction, Western blot analysis, immunofluorescence, and transient transfection analysis to document the presence of functional VDR in both the myocytes and fibroblasts of the heart, as well as in the intact ventricular myocardium. We also demonstrated the presence of 1-alpha-hydroxylase and 24-hydroxylase in the heart, 2 enzymes involved in the synthesis and metabolism of 1,25 dihydroxyvitamin D. VDR is shown to interact directly with the human B-type natriuretic peptide gene promoter, a surrogate marker of the transcriptional response to hypertrophy. Of note, induction of myocyte hypertrophy either in vitro or in vivo leads to an increase in VDR mRNA and protein levels. Collectively, these findings suggest that the key components required for a functional 1,25 dihydroxyvitamin D-dependent signaling system are present in the heart and that this putatively antihypertrophic system is amplified in the setting of cardiac hypertrophy.

Vitamin D

The vitamin D endocrine system plays an essential role in calcium homeostasis and bone metabolism, but research during the past two decades has revealed a diverse range of biological actions that include induction of cell differentiation, inhibition of cell growth, immunomodulation, and control of other hormonal systems. Vitamin D itself is a prohormone that is metabolically converted to the active metabolite, 1,25-dihydroxyvitamin D [1,25(OH)(2)D]. This vitamin D hormone activates its cellular receptor (vitamin D receptor or VDR), which alters the transcription rates of target genes responsible for the biological responses. This review focuses on several recent developments that extend our understanding of the complexities of vitamin D metabolism and actions: the final step in the activation of vitamin D, conversion of 25-hydroxyvitamin D to 1,25(OH)(2)D in renal proximal tubules, is now known to involve facilitated uptake and intracellular delivery of the precursor to 1alpha-hydroxylase. Emerging evidence using mice lacking the VDR and/or 1alpha-hydroxylase indicates both 1,25(OH)(2)D(3)-dependent and -independent actions of the VDR as well as VDR-dependent and -independent actions of 1,25(OH)(2)D(3). Thus the vitamin D system may involve more than a single receptor and ligand. The presence of 1alpha-hydroxylase in many target cells indicates autocrine/paracrine functions for 1,25(OH)(2)D(3) in the control of cell proliferation and differentiation. This local production of 1,25(OH)(2)D(3) is dependent on circulating precursor levels, providing a potential explanation for the association of vitamin D deficiency with various cancers and autoimmune diseases.

Cardiac hypertrophy in vitamin D receptor knockout mice: role of the systemic and cardiac renin-angiotensin systems

Our recent studies suggest that 1,25-dihydroxyvitamin D3 functions as an endocrine suppressor of renin biosynthesis. Genetic disruption of the vitamin D receptor (VDR) results in overstimulation of the renin-angiotensin system (RAS), leading to high blood pressure and cardiac hypertrophy. Consistent with the higher heart-to-body weight ratio, the size of left ventricular cardiomyocytes in VDR knockout (KO) mice was markedly increased compared with wild-type (WT) mice. As expected, levels of atrial natriuretic peptide (ANP) mRNA and circulating ANP were also increased in VDRKO mice. Treatment of VDRKO mice with captopril reduced cardiac hypertrophy and normalized ANP expression. To investigate the role of the cardiac RAS in the development of cardiac hypertrophy, the expression of renin, angiotensinogen, and AT-1a receptor in the heart was examined by real-time RT-PCR and immunostaining. In VDRKO mice, the cardiac renin mRNA level was significantly increased, and this increase was further amplified by captopril treatment. Consistently, intense immunostaining was detected in the left ventricle of captopril-treated WT and VDRKO mice by use of an anti-renin antibody. Levels of cardiac angiotensinogen and AT-1a receptor mRNAs were unchanged in the mutant mice. These data suggest that the cardiac hypertrophy seen in VDRKO mice is a consequence of activation of both the systemic and cardiac RAS and support the notion that 1,25-dihydroxyvitamin D(3) regulates cardiac functions, at least in part, through the RAS.

Human atrial natriuretic peptide infusion for a neonate with congestive heart failure after total correction of total anomalous pulmonary venous connection

A successful case of human atrial natriuretic peptide (HANP) infusion therapy for a neonate who developed congestive heart failure (CHF) after total repair of total anomalous pulmonary venous connection was performed on the first day of life. Following 14h of HANP infusion at incremental doses of 0.125-0.25 microg x kg(-1) x min(-1) urine output and hemodynamics dramatically improved. Urine output increased from 1.1 to 10.6 ml/h (p<0.0001) and good urinary output (13.0 ml/h) was maintained even after discontinuation of the infusion. During the infusion, the heart rate decreased from 166 to 152 beats/min (p<0.0001), and the systemic systolic blood pressure increased from 82 to 103 mmHg (p<0.0001). Central venous pressure was not significantly affected by HANP infusion. This is the first successful case of HANP infusion therapy as the first treatment of post-operative pulmonary hypertension in this age group. This therapy can be used safely and may be useful in neonates with CHF resulting from other causes, but more investigation is needed.

1,25(OH)2 vitamin D3, and retinoic acid antagonize endothelin-stimulated hypertrophy of neonatal rat cardiac myocytes

1,25(OH)2 Vitamin D3 (VD3) and retinoic acid (RA) function as ligands for nuclear receptors which regulate transcription. Though the cardiovascular system is not thought to represent a classical target for these ligands, it is clear that both cardiac myocytes and vascular smooth muscle cells respond to these agents with changes in growth characteristics and gene expression. In this study we demonstrate that each of these ligands suppresses many of the phenotypic correlates of endothelin-induced hypertrophy in a cultured neonatal rat cardiac ventriculocyte model. Each of these agents reduced endothelin-stimulated ANP secretion in a dose-dependent fashion and the two in combination proved to be more effective than either agent used alone (VD3: 49%; RA:52%; VD3 + RA:80% inhibition). RA, at concentrations known to activate the retinoid X receptor, and, to a lesser extent, VD3 effected a reduction in atrial natriuretic peptide, brain natriuretic peptide, and alpha-skeletal actin mRNA levels. Similar inhibition (VD3:30%; RA:33%; VD3 + RA:59% inhibition) was demonstrated when cells transfected with reporter constructs harboring the relevant promoter sequences were treated with VD3 and/or RA for 48 h. These effects were not accompanied by alterations in endothelin-induced c-fos, c-jun, or c-myc gene expression, suggesting either that the inhibitory locus responsible for the reduction in the mRNA levels lies distal to the activation of the immediate early gene response or that the two are not mechanistically coupled. Both VD3 and RA also reduced [3H]leucine incorporation (VD3:30%; RA:33%; VD3 + RA:45% inhibition) in endothelin-stimulated ventriculocytes and, once again, the combination of the two was more effective than either agent used in isolation. Finally, 1,25(OH)2 vitamin D3 abrogated the increase in cell size seen after endothelin treatment. These findings suggest that the liganded vitamin D and retinoid receptors are capable of modulating the hypertrophic process in vitro and that agents acting through these or similar signaling pathways may be of value in probing the molecular mechanisms underlying hypertrophy.