Molecular changes in the early phase of renin-dependent cardiac hypertrophy in hypertensive cyp1a1ren-2 transgenic rats.

An early response to high arterial pressure is the development of cardiac hypertrophy. Functional and transcriptional regulation of ion channels and Ca(2+) handling proteins are involved in this process but the relative contribution of each is unclear. In this study, we investigated the expression of genes involved in action potential generation and Ca(2+) homeostasis of cardiomyocytes in hypertensive cyp1a1ren-2 transgenic rats. In this model, the transgene prorenin was induced by indole-3-carbinol for 2 weeks allowing the induction of hypertension. Electrophysiological recordings from cardiomyocytes of hypertensive rats revealed a slight increase in membrane capacitance consistent with cellular hypertrophy. L-type calcium current density was reduced by 30%. Left ventricles of hypertensive rats showed a significant increase in transcript and protein levels of the cation channel TRPC6 and FK506-binding protein, whereas levels of SERCA2 and voltage-dependent potassium channels K(v)4.2 and K(v)4.3 were found to be decreased. Further, a marked nuclear localization of the transcription factors GATA4 and NFATC4 was observed in cardiac tissue of hypertensive rats. The cyp1a1ren-2 transgenic rat thus appears to be a valid model to investigate early changes in cardiac hypertrophy. This study points to roles for TRPC6, FK506BP, SERCA2, K(v)4.2, and K(v)4.3 in the development of cardiac hypertrophy.

Conditional transgenic expression of fibroblast growth factor 9 in the adult mouse heart reduces heart failure mortality after myocardial infarction.

BACKGROUND: Fibroblast growth factor 9 (FGF9) is secreted from bone marrow cells, which have been shown to improve systolic function after myocardial infarction (MI) in a clinical trial. FGF9 promotes cardiac vascularization during embryonic development but is only weakly expressed in the adult heart. METHODS AND RESULTS: We used a tetracycline-responsive binary transgene system based on the α-myosin heavy chain promoter to test whether conditional expression of FGF9 in the adult myocardium supports adaptation after MI. In sham-operated mice, transgenic FGF9 stimulated left ventricular hypertrophy with microvessel expansion and preserved systolic and diastolic function. After coronary artery ligation, transgenic FGF9 enhanced hypertrophy of the noninfarcted left ventricular myocardium with increased microvessel density, reduced interstitial fibrosis, attenuated fetal gene expression, and improved systolic function. Heart failure mortality after MI was markedly reduced by transgenic FGF9, whereas rupture rates were not affected. Adenoviral FGF9 gene transfer after MI similarly promoted left ventricular hypertrophy with improved systolic function and reduced heart failure mortality. Mechanistically, FGF9 stimulated proliferation and network formation of endothelial cells but induced no direct hypertrophic effects in neonatal or adult rat cardiomyocytes in vitro. FGF9-stimulated endothelial cell supernatants, however, induced cardiomyocyte hypertrophy via paracrine release of bone morphogenetic protein 6. In accord with this observation, expression of bone morphogenetic protein 6 and phosphorylation of its downstream targets SMAD1/5 were increased in the myocardium of FGF9 transgenic mice. CONCLUSIONS: Conditional expression of FGF9 promotes myocardial vascularization and hypertrophy with enhanced systolic function and reduced heart failure mortality after MI. These observations suggest a previously unrecognized therapeutic potential for FGF9 after MI.

Serial measurement of growth-differentiation factor-15 in heart failure: relation to disease severity and prognosis in the Valsartan Heart Failure Trial.

BACKGROUND: Growth-differentiation factor-15 (GDF-15) is emerging as a prognostic biomarker in patients with coronary artery disease. Little is known about GDF-15 as a biomarker in patients with heart failure. METHODS AND RESULTS: The circulating concentration of GDF-15 was measured at baseline (n=1734) and at 12 months (n=1517) in patients randomized in the Valsartan Heart Failure Trial (Val-HeFT). GDF-15 levels at baseline ranged from 259 to 25 637 ng/L and were abnormally high (>1200 ng/L) in 85% of patients. Higher levels were associated with features of worse heart failure and biomarkers of neurohormonal activation, inflammation, myocyte injury, and renal dysfunction. Baseline GDF-15 levels (per 100 ng/L) were associated with the risks of mortality (hazard ratio, 1.017; 95% confidence interval, 1.014 to 1.019; P<0.001) and first morbid event (hazard ratio, 1.020; 95% confidence interval, 1.017 to 1.023; P<0.001). In a comprehensive multiple-variable Cox regression model that included clinical prognostic variables, B-type natriuretic peptide, high-sensitivity C-reactive protein, and high-sensitivity troponin T, GDF-15 remained independently associated with mortality (hazard ratio, 1.007; 95% confidence interval, 1.001 to 1.014; P=0.02) but not first morbid event. At 12 months, the GDF-15 levels had increased by a similar amount in the placebo and valsartan groups (P=0.94). Increases in GDF-15 over 12 months were independently associated with the risks of future mortality and first morbid event also after adjustment for clinical prognostic variables, B-type natriuretic peptide, high-sensitivity C-reactive protein, and high-sensitivity troponin T and their changes. CONCLUSIONS: GDF-15 reflects information from several pathological pathways and provides independent prognostic information in heart failure. GDF-15 levels increase over time, suggesting that GDF-15 reflects a pathophysiological axis that is not completely addressed by the therapies prescribed in Val-HeFT.

Growth-differentiation factor-15 for long-term risk prediction in patients stabilized after an episode of non-ST-segment-elevation acute coronary syndrome.

BACKGROUND: Growth-differentiation factor-15 (GDF-15) has emerged as a prognostic biomarker in patients with non-ST-segment-elevation acute coronary syndrome. This study assessed the time course and the long-term prognostic relevance of GDF-15 levels measured repetitively in patients with non-ST-segment-elevation acute coronary syndrome during 6 months after the acute event. METHODS AND RESULTS: GDF-15 and other biomarkers were measured at randomization, after 6 weeks, and after 3 and 6 months in 950 patients with non-ST-segment-elevation acute coronary syndrome included in the FRagmin and Fast Revascularization during InStability in Coronary artery disease II study. Study end points were death, recurrent myocardial infarction, and their composite during 5-year follow-up. Median GDF-15 levels decreased slightly from 1357 ng/L at randomization to 1302 ng/L at 6 months (P<0.001). GDF-15 was consistently related to cardiovascular risk factors and biochemical markers of hemodynamic stress, renal dysfunction, and inflammation. Moreover, GDF-15 was independently related to the 5-year risk of the composite end point when measured at both 3 months (adjusted hazard ratio, 1.8 [1.0 to 3.0]) and 6 months (adjusted hazard ratio, 2.3 [1.3 to 4.1]). Serial measurements of GDF-15 at randomization and 6 months helped to identify patient cohorts at different levels of risk, with patients with persistently elevated GDF-15 levels >1800 ng/L having the highest rate of the composite end point. CONCLUSIONS: GDF-15 is independently related to adverse events in non-ST-segment-elevation acute coronary syndrome both in the acute setting and for at least 6 months after clinical stabilization. Therefore, continued research on GDF-15 should be focused on the usefulness of GDF-15 for support of clinical management in acute and chronic ischemic heart disease.

Cerivastatin reduces cytokine-induced surface expression of ICAM-1 via increased shedding in human endothelial cells.

Activation of endothelial cells is an incipient process in atherogenesis and leads to induction of the cellular adhesion molecules ICAM-1 and VCAM-1. Their expression can be induced by cytokines as well as other inflammatory mediators. The effects of HMG-CoA reductase inhibitors (statins) include mediation of anti-inflammatory properties. The aim of this study was the comparison of cerivastatin and simvastatin-mediated effects on inflammation-induced ICAM-1 and VCAM-1 expression in human umbilical venous endothelial cells (HUVEC). In HUVEC, TNF-alpha induced ICAM-1 and VCAM-1 mRNA and surface expression. Co-incubation with cerivastatin, but not simvastatin reduced TNF-alpha-induced up-regulation of ICAM-1 surface expression whereas both statins reduced VCAM-1 surface expression; all reductions in surface expression correlated with an increase in the soluble forms of ICAM-1 and VCAM-1 in cell culture supernatants. Mevalonate and nonsteroidal isoprenoids significantly reversed protein expression and shedding. Both statins caused an aggravation of TNF-alpha-induced ICAM-1 and VCAM-1 mRNA expression which was dependent on RNA synthesis. The statin-mediated increase in ICAM-1 and VCAM-1 mRNA expression correlated with the degradation of IkappaBa. Nuclear translocation of p65 was not significantly affected by statin-treatment of cytokine-treated cells. We conclude that cerivastatin and simvastatin reduce TNF-alpha-induced up-regulation of ICAM-1 and VCAM-1 surface expression via increased protein shedding mediated by HMG-CoA reductase inhibition and subsequent isoprenoid depletion.

Blockade of geranylgeranylation by rosuvastatin upregulates eNOS expression in human venous endothelial cells.

Endothelial dysfunction is associated with a reduction in nitric oxide (NO) bioavailability. Positive effects of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) on the improvement of endothelial dysfunction have been shown. We investigated the effects of rosuvastatin and isoprenoid metabolites on endothelial NO synthase (eNOS) mRNA and protein expression in human umbilical venous endothelial cells after exposure to 10(-8)-10(-5) mol/l rosuvastatin for 8 and 12 h. Cell viability was not significantly altered after exposure to the statin for 12h. In a concentration-dependent manner, rosuvastatin upregulated eNOS mRNA and protein expression. The effects on eNOS expression mediated through rosuvastatin could be reversed by treatment with mevalonate indicating inhibition of HMG-CoA reductase as the underlying mechanism. Treatment with geranylgeranylpyrophosphate, but not farnesylpyrophosphate, reversed the increase of eNOS expression induced by rosuvastatin. Rosuvastatin may have beneficial effects on endothelial dysfunction associated with cardiovascular diseases beyond its effects on lowering cholesterol.