Thomas G. von Lueder

Mechanisms of novel cardioprotective functions of CCN2/CTGF in myocardial ischemia-reperfusion injury

CCN2/connective tissue growth factor (CTGF), a CCN family matricellular protein repressed in healthy hearts after birth, is induced in heart failure of various etiologies. Multiple cellular and biological functions have been assigned to CCN2/CTGF depending on cellular context. However, the functions and mechanisms of action of CCN2/CTGF in the heart as well as its roles in cardiac physiology and pathophysiology remain unknown. Transgenic mice with cardiac-restricted overexpression of CTGF (Tg-CTGF) were generated and compared with nontransgenic littermate control (NLC) mice. Tg-CTGF mice displayed slightly lower cardiac mass and inconspicuous increase of myocardial collagen compared with NLC mice but no evidence of contractile dysfunction. Analysis of the myocardial transcriptome by DNA microarray revealed activation of several distinct gene programs in Tg-CTGF hearts involved in cardioprotection and growth inhibition. Indeed, Tg-CTGF mice subjected to ischemia-reperfusion injury by in situ transient occlusion of the left anterior descending coronary artery in vivo displayed reduced vulnerability with markedly diminished infarct size. These findings were recapitulated in isolated hearts perfused with recombinant human (h)CTGF before the ischemia-reperfusion procedure. Consistently, Tg-CTGF hearts, as well as isolated adult cardiac myocytes exposed to recombinant hCTGF, displayed enhanced phosphorylation and activity of the Akt/p70S6 kinase/GSK-3β salvage kinase pathway and induction of several genes with reported cardioprotective functions. Inhibition of Akt activities also prevented the cardioprotective phenotype of hearts from Tg-CTGF mice. This report provides novel evidence that CTGF confers cardioprotection by salvage phosphokinase signaling leading to inhibition of GSK-3β activities, activation of phospho-SMAD2, and reprogramming of gene expression.

Serum uric acid is associated with mortality and heart failure hospitalizations in patients with complicated myocardial infarction: findings from the High-Risk Myocardial Infarction Database Initiative

Serum uric acid (SUA) levels are associated with poorer outcomes in healthy cohorts and patients with stable and unstable coronary heart disease. We investigated the relationship between SUA and clinical outcomes in subjects with acute myocardial infarction (MI) complicated by reduced left ventricular (LV) function, heart failure (HF), or both.

CCN2/CTGF attenuates myocardial hypertrophy and cardiac dysfunction upon chronic pressure-overload

BACKGROUNDnMyocardial CCN2/CTGF (connective tissue growth factor) is strongly induced in heart failure (HF) and acts as a cardioprotective factor in ischemia/reperfusion injury. However, its functional role in myocardial hypertrophy remains unresolved.nnnMETHODS AND RESULTSnTransgenic mice with cardiac-restricted overexpression of CTGF (Tg-CTGF) and non-transgenic littermate control (NLC) mice were subjected to chronic pressure-overload by abdominal aortic banding. After 4weeks of persistent pressure-overload, a time point at which compensatory hypertrophy of the left ventricle (LV) prevails, Tg-CTGF mice displayed diminished increase of LV mass compared with NLC. At study end-point after 12 weeks of sustained aortic constriction, the mice displayed LV dilatation and reduced cardiac function. Repeated transthoracic echocardiography during the 12 weeks of chronic pressure-overload, revealed attenuation of LV dilatation and virtually sustained systolic function in Tg-CTGF mice compared with NLC mice. Also, increase of LV mass was blunted in Tg-CTGF versus NLC mice at study end-point. Consistently, increases of myocardial ANP, BNP and skeletal α-actin mRNA levels were blunted in Tg-CTGF mice subjected to chronic pressure-overload. Furthermore, cardiac myocytes from Tg-CTGF mice displayed increased phospho-NFATc2 levels and attenuated hypertrophic response upon stimulation with α1-adrenoceptor agonist, indicating that CTGF attenuates hypertrophic signaling in cardiac myocytes. Increase of myocardial collagen contents in mice subjected to aortic banding was similar in Tg-CTGF and NLC mice, indicating that CTGF have minimal impact on myocardial collagen deposition.nnnCONCLUSIONnThis study provides novel evidence that CTGF attenuates cardiac hypertrophy upon chronic pressure-overload due to inhibition of signaling mechanisms that promote pathologic myocardial hypertrophy.

Cardiomyocyte-restricted inhibition of G protein-coupled receptor kinase-3 attenuates cardiac dysfunction after chronic pressure overload

Transgenic mice with cardiac-specific expression of a peptide inhibitor of G protein-coupled receptor kinase (GRK)3 [transgenic COOH-terminal GRK3 (GRK3ct) mice] display myocardial hypercontractility without hypertrophy and enhanced α(1)-adrenergic receptor signaling. A role for GRK3 in the pathogenesis of heart failure (HF) has not been investigated, but inhibition of its isozyme, GRK2, has been beneficial in several HF models. Here, we tested whether inhibition of GRK3 modulated evolving cardiac hypertrophy and dysfunction after pressure overload. Weight-matched male GRK3ct transgenic and nontransgenic littermate control (NLC) mice subjected to chronic pressure overload by abdominal aortic banding (AB) were compared with sham-operated (SH) mice. At 6 wk after AB, a significant increase of cardiac mass consistent with induction of hypertrophy was found, but no differences between GRK3ct-AB and NLC-AB mice were discerned. Simultaneous left ventricular (LV) pressure-volume analysis of electrically paced, ex vivo perfused working hearts revealed substantially reduced systolic and diastolic function in NLC-AB mice (n = 7), which was completely preserved in GRK3ct-AB mice (n = 7). An additional cohort was subjected to in vivo cardiac catheterization and LV pressure-volume analysis at 12 wk after AB. NLC-AB mice (n = 11) displayed elevated end-diastolic pressure (8.5 ± 3.1 vs. 2.9 ± 1.2 mmHg, P < 0.05), reduced cardiac output (3,448 ± 323 vs. 4,488 ± 342 μl/min, P < 0.05), and reduced dP/dt(max) and dP/dt(min) (both P < 0.05) compared with GRK3ct-AB mice (n = 16), corroborating the preserved cardiac structure and function observed in GRK3ct-AB hearts assessed ex vivo. Increased cardiac mass and myocardial mRNA expression of β-myosin heavy chain confirmed the similar induction of cardiac hypertrophy in both AB groups, but only NLC-AB hearts displayed significantly elevated mRNA levels of brain natriuretic peptide and myocardial collagen contents as well as reduced β(1)-adrenergic receptor responsiveness to isoproterenol, indicating increased LV wall stress and the transition to HF. Inhibition of cardiac GRK3 in mice does not alter the hypertrophic response but attenuates cardiac dysfunction and HF after chronic pressure overload.

Separate mechanisms cause anemia in ischemic vs. nonischemic murine heart failure

In ischemic congestive heart failure (CHF), anemia is associated with poor prognosis. Whether anemia develops in nonischemic CHF is uncertain. The hematopoietic inhibitors TNF-alpha and nitric oxide (NO) are activated in ischemic CHF. We examined whether mice with ischemic or nonischemic CHF develop anemia and whether TNF-alpha and NO are involved. We studied mice (n = 7-9 per group) with CHF either due to myocardial infarction (MI) or to overexpression of the Ca(2+)-binding protein calsequestrin (CSQ) or to induced cardiac disruption of the sarcoplasmic reticulum Ca(2+)-ATPase 2 gene (SERCA2 KO). Hematopoiesis was analyzed by colony formation of CD34(+) bone marrow cells. Hemoglobin concentration was 14.0 +/- 0.4 g/dl (mean +/- SD) in controls, while it was decreased to 10.1 +/- 0.4, 9.7 +/- 0.4, and 9.6 +/- 0.3 g/dl in MI, CSQ, and SERCA2 KO, respectively (P < 0.05). Colony numbers per 100,000 CD34(+) cells in the three CHF groups were reduced to 33 +/- 3 (MI), 34 +/- 3 (CSQ), and 39 +/- 3 (SERCA2 KO) compared with 68 +/- 4 in controls (P < 0.05). Plasma TNF-alpha nearly doubled in MI, and addition of anti-TNF-alpha antibody normalized colony formation. Inhibition of colony formation was completely abolished with blockade of endothelial NO synthase in CSQ and SERCA2 KO, but not in MI. In conclusion, the mechanism of anemia in CHF depends on the etiology of cardiac disease; whereas TNF-alpha impairs hematopoiesis in CHF following MI, NO inhibits blood cell formation in nonischemic murine CHF.

Comorbidities and Polypharmacy

Heart failure (HF) is predominantly a disease that affects the elderly population, a cohort in which comorbidities are common. The majority of comorbidities and the degree of their severity have prognostic implications in HF. Polypharmacy in HF is common, has increased throughout the past 2 decades, and may pose a risk for adverse drug interactions, accidental overdosing, or medication nonadherence. Polypharmacy, in particular in the elderly, is rarely assessed in traditional clinical trials, highlighting a need for entirely novel HF research strategies.

Adrenomedullin is increased in alveolar macrophages and released from the lungs into the circulation in severe heart failure

Adrenomedullin (AM) is a potent vasorelaxing peptide with natriuretic, diuretic, and growth inhibitory properties. Plasma concentrations and myocardial AM expression are increased in heart failure (HF). Since AM and AM binding sites are abundantly expressed in the lungs, we investigated to what extent pulmonary AM and AM receptor subtypes [CRLR/RAMP2 (AM1) and CRLR/RAMP3 (AM2)] are changed in HF and whether the lungs contribute to the increased plasma concentrations of AM reported in HF. Pulmonary AM mRNA and protein expression were increased by 2.8- and 2.6-fold, respectively, whereas mRNA expression of RAMP2 and CRLR was decreased in rats with HF 7xa0days after induction of MI compared to sham-operated rats (Pxa0<xa00.05). Pulmonary AM receptor density was substantially decreased in HF rats compared to sham (3.7xa0±xa00.6 vs. 29.9xa0±xa01.1 fmol/mg membrane protein; Pxa0<xa00.05). Immunoreactivities against AM and the AM receptor components CRLR, RAMP2, and RAMP3 in the pulmonary tissue were seen in vascular smooth muscle cells, vascular endothelial cells, and in alveolar macrophages. AM mRNA expression in alveolar macrophages obtained from HF rats by bronchoalveolar lavage was 2.9-fold higher than in sham-operated rats (Pxa0<xa00.05). An even more substantial increase of AM mRNA expression was found in alveolar macrophages from patients with HF (10-fold, Pxa0<xa00.05), and this increase displayed a negative correlation to left ventricular systolic function (Pxa0<xa00.05). Furthermore, a net release of AM from the lungs into the circulation was only found in HF patients with the most severe left ventricular systolic dysfunction. Thus, our data demonstrate increased expression and decreased receptor binding of AM in the lungs in severe HF. Furthermore, our data indicate that alveolar macrophages are an important source of pulmonary AM in both experimental and clinical HF. Finally, a net release of AM from the lungs into the circulation was only found in patients with severe systolic dysfunction.

Rheumatic mitral valve stenosis mimicking advanced lung cancer

This report describes a patient with a perihilar mass and mediastinal lymphadenopathy mimicking advanced lung cancer. The patient, a 45-year old regular smoker, was admitted to hospital for dyspnea and tachyarrhythmia, and during hospitalization he was diagnosed with severe rheumatic mitral valve stenosis (MVS) and aortic regurgitation as well as pulmonary venous hypertension. Surgical valve replacement and removal of an atrial thrombus was delayed considerably by diagnostic work-up for suspected malignancy. After cardiac surgery had been performed, recovery was uneventful. On follow-up 1 year later, echocardiography showed well-functioning prosthetic mitral and aortic valves, and normal findings on chest X-ray. Perihilar masses and mediastinal lymphadenopathy presented in this case constitute infrequent yet established findings in MVS, resulting from pulmonary venous congestion and hypertension, and focal lymphedema.

Heart rate prediction of outcome in heart failure following myocardial infarction depend on heart rhythm status an analysis from the high-risk myocardial infarction database initiative

BACKGROUNDnHeart rate has been reported to be associated with adverse outcome in heart failure (HF) and myocardial infarction (MI), but conflicting evidence exists regarding its impact in patients with associated atrial fibrillation (AF).nnnOBJECTIVESnWe investigated the differential impact of heart rate on clinical outcomes according to the presence or absence of AF in patients with reduced systolic function and/or HF after MI.nnnMETHODSnWe studied the association of heart rate with outcome using Cox-models in a merged dataset (n=28,771) of four randomized trials (CAPRICORN, EPHESUS, OPTIMAAL, and VALIANT).nnnRESULTSnAt baseline, 3736 (13%) patients had AF. We identified a significant interaction between AF and heart rate, and a decreasing effect of heart rate with time, heart rate being less associated with outcome after 1year of follow-up (both p for interaction <0.001). We report associations with outcome separately in patients with and without AF. In addition, as neutral associations with outcome after 1year were estimated after adjustment on confounding factors, only association for the first year follow-up were provided. 10-bpm increase in heart rate conferred increased risk for all-cause mortality (1.27 [1.21 to 1.33], p<0.0001), CV-mortality (1.28 [1.22 to 1.34], p<0.0001), and HF-hospitalisation (1.25 [1.19 to 1.31], p<0.0001) in patients without AF. In contrast, in patients with AF, the incremental risk for 10-bpm increase in heart rate was attenuated for all-cause (1.14 [1.06 to 1.23], p=0.0007), CV-mortality (1.12 [1.03 to 1.22], p=0.006), and HF-hospitalisation (1.16 [1.07 to 1.26], p=0.0006, p for interaction with AF <0.001 for all outcomes).nnnCONCLUSIONSnIn patients with reduced systolic function and/or HF post-MI, higher heart rate predicts increased major cardiovascular events during the first year following MI in patients without AF. This association is markedly attenuated in subjects with AF.