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Vitamin D deficiency is one of the most common nutritional deficiencies worldwide. Maternal vitamin D deficiency is associated with increased susceptibility to hypertension in offspring, but the reasons for this remain unknown. The aim of this study was to determine if parental vitamin D deficiency leads to altered DNA methylation in offspring that may relate to hypertension. Male and female Sprague-Dawley rats were fed a standard or vitamin D-depleted diet. After 10 wk, nonsibling rats were mated. The conceived pups received standard chow. We observed an increased systolic and diastolic blood pressure in the offspring from depleted parents (F1-depl). Genome-wide methylation analyses in offspring identified hypermethylation of the promoter region of the Pannexin-1 ( Panx1) gene in F1-depl rats. Panx1 encodes a hemichannel known to be involved in endothelial-dependent relaxation, and we demonstrated that in F1-depl rats the increase in blood pressure was associated with impaired endothelial relaxation of the large vessels, suggesting an underlying biological mechanism of increased blood pressure in children from parents with vitamin deficiency. Parental vitamin D deficiency is associated with epigenetic changes and increased blood pressure levels in offspring.

Contains fulltext : 154705.pdf (Publisher’s version ) (Open Access) Pathological cardiac hypertrophy is characterized by a shift in metabolic substrate utilization from fatty acids to glucose, but the molecular events underlying the metabolic remodeling remain poorly understood. Here, we investigated the role of liver X receptors (LXRs), which are key regulators of glucose and lipid metabolism, in cardiac hypertrophic pathogenesis. Using a transgenic approach in mice, we show that overexpression of LXRalpha acts to protect the heart against hypertrophy, fibrosis, and dysfunction. Gene expression profiling studies revealed that genes regulating metabolic pathways were differentially expressed in hearts with elevated LXRalpha. Functionally, LXRalpha overexpression in isolated cardiomyocytes and murine hearts markedly enhanced the capacity for myocardial glucose uptake following hypertrophic stress. Conversely, this adaptive response was diminished in LXRalpha-deficient mice. Transcriptional changes induced by LXRalpha overexpression promoted energy-independent utilization of glucose via the hexosamine biosynthesis pathway, resulting in O-GlcNAc modification of GATA4 and Mef2c and the induction of cytoprotective natriuretic peptide expression. Our results identify LXRalpha as a key cardiac transcriptional regulator that helps orchestrate an adaptive metabolic response to chronic cardiac stress, and suggest that modulating LXRalpha may provide a unique opportunity for intervening in myocyte metabolism.

Contains fulltext : 182343.pdf (Publisher’s version ) (Closed access) In response to heart failure (HF), the heart reacts by repressing adult genes and expressing fetal genes, thereby returning to a more fetal-like gene profile. To identify genes involved in this process, we carried out transcriptional analysis on murine hearts at different stages of development and on hearts from adult mice with HF. Our screen identified Oplah, encoding for 5-oxoprolinase, a member of the gamma-glutamyl cycle that functions by scavenging 5-oxoproline. OPLAH depletion occurred as a result of cardiac injury, leading to elevated 5-oxoproline and oxidative stress, whereas OPLAH overexpression improved cardiac function after ischemic injury. In HF patients, we observed elevated plasma 5-oxoproline, which was associated with a worse clinical outcome. Understanding and modulating fetal-like genes in the failing heart may lead to potential diagnostic, prognostic, and therapeutic options in HF.

BackgroundInterleukin-6 (IL-6) levels are upregulated in myocardial infarction. Recent data suggest a causal role of the IL-6 receptor (IL-6R) in coronary heart disease. We evaluated if IL-6R blockade by a monoclonal antibody (MR16-1) prevents the heart from adverse left ventricular remodeling in a mouse model of ischemia-reperfusion (I/R).MethodsCJ57/BL6 mice underwent I/R injury (left coronary artery ligation for 45 minutes) or sham surgery, and thereafter received MR16-1 (2mg/mouse) 5 minutes before reperfusion and 0.5mg/mouse weekly during four weeks, or control IgG treatment. Cardiac Magnetic Resonance Imaging (CMR) and hemodynamic measurements were performed to determine cardiac function after four weeks.ResultsI/R caused left ventricular dilatation and a decrease in left ventricular ejection fraction (LVEF). However, LVEF was significantly lower in the MR16-1 treatment group compared to the IgG group (28 +/- 4% vs. 35 +/- 6%, p = 0.02; sham 45 +/- 6% vs. 43 +/- 4%, respectively; p = NS). Cardiac relaxation (assessed by dP/dT) was not significantly different between the MR16-1 and IgG groups. Also, no differences were observed in histological myocardial fibrosis, infarct size and myocyte hypertrophy between the groups.ConclusionBlockade of the IL-6R receptor by the monoclonal MR16-1 antibody for four weeks started directly after I/R injury did not prevent the process of cardiac remodeling in mice, but rather associated with a deterioration in the process of adverse cardiac remodeling.

Suicidal death of erythrocytes (eryptosis) is characterized by cell shrinkage and exposure of phosphatidylserine (PS) residues at the cell surface. Excessive eryptosis may lead to anaemia. We aimed to study the role of eryptosis in heart failure (HF)-associated anaemia.We measured eryptosis in rodent models of HF. Typical measures of eryptosis including PS-exposure, increased intracellular Ca-2 levels, and decreased cell volume were determined by flow cytometry. Transgenic REN2 rats displayed mild anaemia which was associated with a two-fold increase in erythrocyte PS-exposure when compared with Sprague Dawley (SD) control rats (P 0.01). Upon stimulation with eryptotic triggers such as oxidative stress, hyperosmotic shock and energy depletion, eryptosis was more prominent in REN2 as shown by increased PS-exposure, cytosolic Ca-2 influx, and cell shrinkage (P 0.05 vs. SD). Increasing cytosolic Ca-2 levels resulted in a stronger increase in PS-exposure in REN2 erythrocytes (P 0.01 vs. SD). Accordingly, inhibition of Ca-2 entry blunted the increased PS-exposure upon oxidative stress. The REN2 rats had significantly higher reticulocytes (REN2: 10.6 2.3; SD: 5.4 0.1; P 0.05) and erythrocyte turnover was increased, indicated by increased clearance of eryptotic erythrocytes. Eryptosis was also increased in a rat model of hypertensive cardiac remodelling (uninephrectomized rats implanted with deoxycorticosterone acetate pellets), in mice after transverse aortic constriction, as well as in a small proof-of-concept study in human HF patients.Eryptosis is increased during HF development and could contribute to HF-associated anaemia. Eryptosis may therefore become a novel target for therapy in HF-associated anaemia.

Liver X receptor (LXR) is a nuclear receptor regulating cholesterol metabolism. Liver X receptor has also been shown to exert anti-proliferative and anti-inflammatory properties. In this study, we evaluated the effect of LXR activation on cardiac hypertrophy in vitro and in vivo.Treatment with the synthetic LXR agonist T0901317 (T09) attenuated the hypertrophic response of cultured cardiomyocytes to endothelin-1 almost to control levels. siRNA interference showed that this effect was indeed LXR specific. To corroborate these findings in vivo, abdominal aortic constriction (AC) was used as a pressure overload model to induce cardiac hypertrophy in wild-type and LXR-alpha-deficient (LXR-alpha(-/-)) mice. In wild-type mice, T09 treatment resulted in a decrease of cardiac wall thickening 4 and 7 weeks after AC. Also, after 7 weeks of AC, mean arterial blood pressure and left ventricular weight/body weight (LVW/BW) ratios were decreased in T09 treated mice. These effects were not observed in LXR-alpha(-/-) mice, indicating that the beneficial effect of LXR activation on cardiac hypertrophy is attributable to the LXR-alpha isoform. T09 induced robust cardiac expression of metabolic genes which are downstream of LXR-alpha, such as SREBP-1c, ABCA1, and ABCG1.Together these results indicate that LXR exerts salutary effects in cardiac hypertrophy, possibly via metabolic remodelling.

Contains fulltext : 127542.pdf (Publisher’s version ) (Open Access) The (pro)renin-renin receptor, (P)RR has been claimed to be a novel element of the renin-angiotensin system (RAS). The function of (P)RR has been widely studied in renal and vascular pathology but the cardio-specific function of (P)RR has not been studied in detail. We therefore generated a transgenic mouse (Tg) with cardio-restricted (P)RR overexpression driven by the alpha-MHC promotor. The mRNA expression of (P)RR was approximately 170-fold higher (P

Background: Atrial fibrillation (AF) is often preceded by underlying cardiac diseases causing ventricular pressure overload.Objective: It was our aim to investigate the progression of atrial remodeling in a small animal model of ventricular pressure overload and its association with induction of AF.Methods: Male mice were subjected to transverse aortic constriction (TAC) or sham operation. After four or eight weeks, echocardiographic measurements and hemodynamic measurements were made and AF induction was tested. The hearts were either fixed in formalin or ventricles and atria were separated, weighed and snap-frozen for RNA analysis.Results: Four weeks of pressure overload induced ventricular hypertrophy and minor changes in the atria. After eight weeks a significant reduction in left ventricular function occurred, associated with significant atrial remodeling including increased atrial weight, a trend towards an increased left atrial cell diameter, atrial dilatation and increased expression of markers of hypertrophy and inflammation. Histologically, no fibrosis was found in the left atrium. But atrial gene expression related to fibrosis was increased. Minor changes related to electrical remodeling were observed. AF inducibility was not different between the groups. Left ventricular end diastolic pressures were increased and correlated with the severity of atrial remodeling but not with AF induction.Conclusion: Permanent ventricular pressure overload by TAC induced atrial remodeling, including hypertrophy, dilatation and inflammation. The extent of atrial remodeling was directly related to LVEDP and not duration of TAC per se.