Gene deletion of dopamine beta-hydroxylase and alpha1-adrenoceptors demonstrates involvement of catecholamines in vascular remodeling.

In vitro studies have shown that stimulation of alpha1-adrenoceptors (ARs) directly induces proliferation, hypertrophy, and migration of arterial smooth muscle cells and adventitial fibroblasts. In vivo studies confirmed these findings and showed that catecholamine trophic activity becomes excessive after experimental balloon injury and contributes to neointimal growth, adventitial thickening, and lumen loss. However, past studies have been limited by selectivity of pharmacological agents. The aim of this study, in which mice devoid of norepinephrine and epinephrine synthesis [dopamine beta-hydroxylase (DBH-/-)] or deficient in alpha1-AR subtypes expressed in murine carotid (alpha1B-AR-/- and alpha1D-AR-/-) were used, was to test the hypothesis that catecholamines contribute to wall hypertrophy after injury. At 3 wk after injury of wild-type mice, lumen area and carotid circumference increased significantly, and hypertrophy of media and adventitia was in excess of that needed to restore circumferential wall stress to normal. In DBH-/- and alpha1B-AR-/- mice, increases in lumen area, circumference, and hypertrophy of the media and adventitia were reduced by 50-91%, resulting in restoration of wall tension to nearly normal (DBH-/-) or normal (alpha1B-AR-/-). In contrast, in alpha1D-AR-/- mice, increases in lumen area, circumference, and wall hypertrophy were unaffected and wall thickening remained in excess of that required to return tension to normal. When examined 5 days after injury, proliferation and leukocyte infiltration were inhibited in DBH-/- mice. These studies suggest that the trophic effects of catecholamines are mediated primarily by alpha1B-ARs in mouse carotid and contribute to hypertrophic growth after vascular injury.

Thérapie cellulaire régénérative en cardiologie: le futur au présent [Cell-based regenerative therapy in cardiology: the future at present].

Cell-based regenerative therapy treatment of cardiovascular diseases considered as irreversible, as acute myocardial infarction, chronic ischemic heart failure, non-ischemic dilated cardiomyopathy and refractory angina pectoris. Large randomized clinical trials with hard clinical endpoints are still necessary before considering cell-based regenerative therapy as a valuable alternative therapeutic option in cardiology.

The Macrocirculation and Microcirculation of Hypertension.

Changes in vascular structure that accompany hypertension may contribute to hypertensive end-organ damage. Both the macrovascular and microvascular levels should be considered, as interactions between them are believed to be critically important. Regarding the macrocirculation, the article first reviews basic concepts of vascular biomechanics, such as arterial compliance, arterial distensibility, and stress-strain relationships of arterial wall material, and then reviews how hypertension affects the properties of conduit arteries, particularly examining evidence that it accelerates the progressive stiffening that normally occurs with advancing age. High arterial stiffness may increase central systolic and pulse pressure by two different mechanisms: 1) Abnormally high pulse wave velocity may cause pressure waves reflected in the periphery to reach the central aorta in systole, thus augmenting systolic pressure; 2) In the elderly, the interaction of the forward pressure wave with high arterial stiffness is mostly responsible for abnormally high pulse pressure. At the microvascular level, hypertensive disease is characterized by inward eutrophic or hypertrophic arteriolar remodeling and capillary rarefaction. These abnormalities may depend in part on the abnormal transmission of highly pulsatile blood pressure into microvascular networks, especially in highly perfused organs with low vascular resistance, such as the kidney, heart, and brain, where it contributes to hypertensive end-organ damage.

Cardiac raptor ablation impairs adaptive hypertrophy, alters metabolic gene expression, and causes heart failure in mice.

Background- Cardiac hypertrophy involves growth responses to a variety of stimuli triggered by increased workload. It is an independent risk factor for heart failure and sudden death. Mammalian target of rapamycin (mTOR) plays a key role in cellular growth responses by integrating growth factor and energy status signals. It is found in 2 structurally and functionally distinct multiprotein complexes called mTOR complex (mTORC) 1 and mTORC2. The role of each of these branches of mTOR signaling in the adult heart is currently unknown. Methods and Results- We generated mice with deficient myocardial mTORC1 activity by targeted ablation of raptor, which encodes an essential component of mTORC1, during adulthood. At 3 weeks after the deletion, atrial and brain natriuretic peptides and β-myosin heavy chain were strongly induced, multiple genes involved in the regulation of energy metabolism were altered, but cardiac function was normal. Function deteriorated rapidly afterward, resulting in dilated cardiomyopathy and high mortality within 6 weeks. Aortic banding-induced pathological overload resulted in severe dilated cardiomyopathy already at 1 week without a prior phase of adaptive hypertrophy. The mechanism involved a lack of adaptive cardiomyocyte growth via blunted protein synthesis capacity, as supported by reduced phosphorylation of ribosomal S6 kinase 1 and 4E-binding protein 1. In addition, reduced mitochondrial content, a shift in metabolic substrate use, and increased apoptosis and autophagy were observed. Conclusions- Our results demonstrate an essential function for mTORC1 in the heart under physiological and pathological conditions and are relevant for the understanding of disease states in which the insulin/insulin-like growth factor signaling axis is affected such as diabetes mellitus and heart failure or after cancer therapy.

Characterization of the role of Rho activating signalling complexes in G protein-coupled receptor induced cardiac fibrosis

Dans certaines conditions pathologiques, telles que l'hypertension artérielle ou l'infarctus du myocarde, le coeur répond à une augmentation de la post-charge par des processus de remodelage aboutissant à une hypertrophie du ventricule gauche. L'hypertrophie cardiaque est caractérisée par une croissance hypertrophique des cardiomyocytes, ainsi que par une différenciation des fibroblastes en un phenotype présentant une capacité accrue de synthèse protéiques, nommés myofibroblastes. Ceci résulte en une accumulation excessive des constituants de la matrice extracellulaire, ou autrement dit fibrose. En raison de son effet délétère sur la contractilité du coeur, menant sur le long terme à une insuffisance cardiaque, de nombreux efforts ont été déployés, afin de définir les mécanismes moléculaires impliqués dans la réponse profibrotique. A ce jour, de nombreuses études indiquent que la petite GTPase RhoA pourrait être un médiateur important de la réponse profibrotique du myocarde. Cependant, les facteurs d'échanges impliqués dans la transduction de signaux profibrotiques, via la régulation de son activité au niveau des fibroblastes cardiaques, n'ont pas encore été identifiés. De précédentes études menées dans le laboratoire, ont identifiées une nouvelle protein d'ancrage de la PKA, exprimée majoritairement dans le coeur, nommée AKAP-Lbc. Il a été montré que cette protéine, en plus de sa fonction de protein d'ancrage, possédait une activité de facteur d'échange de nucléotide guanine (GEF) pour la petite GTPase RhoA. Au niveau des cardiomyocytes, il a été montré que l'AKAP-Lbc participe à une voie de signalisation pro-hypertrophique, incluant la sous-unité alpha de la protéine G hétérotrimerique G12 et RhoA. Chose intéressante, des observations antérieures à cette étude, indiquent que dans le coeur, l'AKAP-Lbc est également exprimée dans les fibroblastes. Cependant aucunes études n'a encore reporté de fonction pour ce facteur d'échange dans les fibroblastes cardiaques. Dans ce travail, les résultats obtenus indiquent que dans les fibroblastes cardiaques, I'activation de RhoA par l'AKAP-Lbc est impliquée dans la transmission de signaux profibrotiques, en aval des récépteurs à l'angiotensine II. En particulier, nous avons observé que la suppression de l'expression de l'AKAP-Lbc dans les fibroblastes ventriculaires de rat adultes, réduisait fortement Γ activation de Rho induite par l'angiotensine II, la déposition de collagène, la capacité migratoire des fibroblastes ainsi que leur différenciation en myofibroblastes. A notre connaissance, l'AKAP-Lbc est le premier RhoGEF identifié comme médiateur de la réponse profibrotique dans les fibroblastes cardiaques. - In pathological conditions such as chronic hypertension or myocardial infarction, the myocardium is subjected to various biomechanical and biochemical stresses, and undergoes an adverse ventricular remodelling process associated with cardiomyocytes hypertrophy and excess deposition of extracellular matrix proteins resulting in fibrosis. During the fibrotic response, cardiac fibroblasts differentiate into a more mobile and contractile phenotype termed myofibroblasts. These cells, possess a greater synthetic ability to produce ECM proteins and have been implicated in diseases with increased ECM deposition including cardiac fibrosis. Because fibrosis impairs myocardial contractility and is associated with the progression to heart failure, a major cause of lethality worldwide, many efforts have been made to define the molecular players involved in this process. During these last years, increasing evidence suggests a role for the small GTPase RhoA in mediating the fibrotic response in CFbs. However the identity of the exchange factors that modulate its activity and transduce fibrotic signals in CFbs is still unknown. Earlier work in our laboratory identified a novel PKA anchoring protein expressed in the heart termed AKAP-Lbc that has been shown to function as anchoring protein as well as a guanine nucleotide exchange factor (GEF) for the small GTPase RhoA. In response to several hypertrophic stimuli we have shown that RhoGEF activity of AKAP-Lbc mediated by Gan promotes the activation of a signaling pathway including RhoA, leading to cardiomyocytes hypertrophy. Within the heart, previous observations made in the laboratory indicated that AKAP-Lbc was also expressed in fibroblasts. However its role in cardiac fibroblasts remained to be determined. In the present study, we show that AKAP-Lbc is critical for activating RhoA and transducing profibrotic signals downstream of angiotensin II receptors in cardiac fibroblasts. In particular, our results indicate that suppression of AKAP-Lbc expression by infecting adult rat ventricular fibroblasts with lentiviruses encoding AKAP-Lbc specific short hairpin RNAs strongly reduces angiotensin II-induced RhoA activation, collagen deposition as well as cell migration and differentiation. These findings identify AKAP-Lbc as the first Rho-guanine nucleotide exchange factor involved in a profibrotic signalling pathway at the level of cardiac fibroblasts.

Spirometric abnormalities in patients with Fabry disease and effect of enzyme replacement therapy

Aim: Fabry disease is an X-linked genetic disorder due to deficiency of the lysosomal enzyme a-galactosidase A, which leads to the accumulation of neutral glycosphingolipids within the lysosomes of almost all tissues. Clinical manifestations usually include acroparaesthesia, renal insufficiency and cardiomyopathy. Recently, pulmonary manifestations consisting of progressive obstructive airway disease have been reported. The aim of this study was to analyse the cross-sectional prevalence of airflow obstruction in a Swiss cohort of patients, and in selected cases, to evaluate the impact of enzyme replacement therapy (ERT) with agalsidase alfa (ReplagalTM; TKT - 5S). Methods: Forty-four patients (27 men, 17 women) were included in the study and received pulmonary function testing. Fifteen patients underwent spirometry after ERT. Results: Twelve patients (nine men) had chronic obstructive pulmonary disease according to the Global Obstructive Lung Disease (GOLD) initiative criteria: forced expiratory volume (FEV1)/forced vital capacity (FVC) 50.7), but only one was an active smoker and one a previous smoker. FEV1/ FVC as percentage predicted was weakly correlated with age (r=0.42, p=0.005, calculated by Pearson product-moment correlation), demonstrating that airway obstruction occurs in the late stages of the disease. Median FEV1 in patients with obstruction was 67% of predicted (range, 45-90%). Reversibility of FEV1 after b2-agonist inhalation never exceeded 8% of predicted. Diffusing capacity of the lung for carbon monoxide (DLCO) was measured in 13 individuals with a median of 88% of predicted (range, 39-125%). After 15+9 months of ERT, spirometry measurements were recorded in 15 patients. Decline in FEV1 was -2+5% of predicted. (p40.05, measured by the Wilcoxon signed-rank test). Median change in DLCO was -10% of predicted (-40 to +25%, p40.05). High resolution computed tomography scans demonstrated a moderate thickening of the bronchial wall in affected individuals, without evidence of emphysema. Conclusion: We conclude that Fabry disease can be complicated by significant airway obstruction, particularly in patients in the advanced stages of the disease, and that in the period studied, ERT had no demonstrable impact on pulmonary function.

Cardiac re-synchronization therapy in a patient with isolated ventricular non-compaction: a case report.

Isolated ventricular non-compaction (IVNC) is a rare, congenital, unclassified cardiomyopathy characterized by prominent trabecular meshwork and deep recesses. Major clinical manifestations of IVNC are heart failure, atrial and ventricular arrhythmias, and thrombo-embolic events. We describe a case of a 69-year-old woman in whom the diagnosis of IVNC was discovered late, whereas former echocardiographic examinations were considered normal. She was known for systolic left ventricular dysfunction for 3 years and then became symptomatic (NYHA III). In the past, she suffered from multiple episodes of deep vein thrombosis and pulmonary embolism. Electrocardiogram revealed a wide QRS complex, and transthoracic echocardiography showed typical apical thickening of the left and right ventricular myocardial wall with two distinct layers. The ratio of non-compacted to compacted myocardium was >2:1. Cardiac MRI confirmed the echocardiographic images. Cerebral MRI revealed multiple ischaemic sequellae. In view of the persistent refractory, heart failure in medical treatment of patients with classical criteria for cardiac re-synchronization therapy, as well as the ventricular arrhythmias, a biventricular automatic intracardiac defibrillator (biventricular ICD) was implanted. The 2-year follow-up period was characterized by improvement of NYHA functional class from III to I and increasing in left ventricular function. We hereby present a case of IVNC with favourable outcome after biventricular ICD implantation. Cardiac re-synchronization therapy could be considered in the management of this pathology.

Activation of PPAR delta Regulates Ywhae (Encoding 14-3-3 epsilon Protein), a Gene Required for Ventricular Morphogenesis

Cardiac ventricular morphogenesis is a key developmental stage during which the ventricles grow considerably in size, but the transcriptional pathways controlling this process remains poorly understood. 14-3-3_ is a member of a conserved protein family that regulates a wide range of processes such as transcription, apoptosis and proliferation by binding to the phospho-serine/threonine residues of its target proteins. We found that deletion of the Ywhae gene (encoding 14-3-3_) in mice leads to abnormal ventricular morphogenesis and an embryonic cardiomyopathy (Cieslik KA et al, Circ. Res. 2008, abstract). Interestingly, we recently showed in cultured cells that the Ywhae gene is regulated directly by peroxisome proliferator-activated receptor _ (PPAR_) (Brunelli L et al, Circ. Res. 2007), a ligand-inducible nuclear receptor that controls energy metabolism and development. Postnatal cardiac-specific deletion of the Ppard gene in mice causes a lethal dilated cardiomyopathy, but it is still unknown whether PPAR_ regulates genes involved in heart development. We hypothesized that the expression of the Ywhae gene is responsive to PPAR_ during heart development. We confirmed that PPAR_ is expressed in the heart during development, and found higher expression at E10.5 compared to later gestational ages. We showed by immunofluorescence that a PPAR_ agonist (50 _M L-165,041 for 24 hr) upregulates 14-3-3_ in primary cardiomyocytes. We showed that when P19CL6 cells are driven towards cardiomyocyte lineage by dimethyl sulfoxide (DMSO), 14-3-3_ levels increase 4-fold, while L-165,041 treatment increases levels by an additional 50%. Based on previous work in mice (Leibowitz MD et al, FEBS Lett. 2000; Letavernier E et al, J. Am. Soc. Nephrol. 2005), we tested the response of Ywhae to PPAR_ in vivo . We fed 30 mg/kg/day L-165,041 to 14-3-3__/_ adult pregnant mice for 3 days starting at E9.5 and assessed Ywhae mRNA levels in embryonic hearts at E12.5. Baseline mRNA levels in Ywhae_/_ hearts were double that of Ywhae_/ hearts, while L-165,041 upregulated Ywhae mRNA levels in both Ywhae_/_ and Ywhae_/ hearts by 65%. These results indicate that Ywhae responds to PPAR_ in vivo, and suggest that PPAR_ regulates Ywhae during ventricular morphogenesis.

Identification of heart rate-associated loci and their effects on cardiac conduction and rhythm disorders.

Elevated resting heart rate is associated with greater risk of cardiovascular disease and mortality. In a 2-stage meta-analysis of genome-wide association studies in up to 181,171 individuals, we identified 14 new loci associated with heart rate and confirmed associations with all 7 previously established loci. Experimental downregulation of gene expression in Drosophila melanogaster and Danio rerio identified 20 genes at 11 loci that are relevant for heart rate regulation and highlight a role for genes involved in signal transmission, embryonic cardiac development and the pathophysiology of dilated cardiomyopathy, congenital heart failure and/or sudden cardiac death. In addition, genetic susceptibility to increased heart rate is associated with altered cardiac conduction and reduced risk of sick sinus syndrome, and both heart rate-increasing and heart rate-decreasing variants associate with risk of atrial fibrillation. Our findings provide fresh insights into the mechanisms regulating heart rate and identify new therapeutic targets.

A-Kinase Anchoring Protein Lbc Coordinates a p38 Activating Signaling Complex Controlling Compensatory Cardiac Hypertrophy.

In response to stress, the heart undergoes a remodeling process associated with cardiac hypertrophy that eventually leads to heart failure. A-kinase anchoring proteins (AKAPs) have been shown to coordinate numerous prohypertrophic signaling pathways in cultured cardiomyocytes. However, it remains to be established whether AKAP-based signaling complexes control cardiac hypertrophy and remodeling in vivo. In the current study, we show that AKAP-Lbc assembles a signaling complex composed of the kinases PKN, MLTK, MKK3, and p38α that mediates the activation of p38 in cardiomyocytes in response to stress signals. To address the role of this complex in cardiac remodeling, we generated transgenic mice displaying cardiomyocyte-specific overexpression of a molecular inhibitor of the interaction between AKAP-Lbc and the p38-activating module. Our results indicate that disruption of the AKAP-Lbc/p38 signaling complex inhibits compensatory cardiomyocyte hypertrophy in response to aortic banding-induced pressure overload and promotes early cardiac dysfunction associated with increased myocardial apoptosis, stress gene activation, and ventricular dilation. Attenuation of hypertrophy results from a reduced protein synthesis capacity, as indicated by decreased phosphorylation of 4E-binding protein 1 and ribosomal protein S6. These results indicate that AKAP-Lbc enhances p38-mediated hypertrophic signaling in the heart in response to abrupt increases in the afterload.

Le point sur l'ergométrie en 2012 dans le diagnostic de la maladie coronarienne.

Background In patients presenting with acute cardiac symptoms, abnormal ECG and raised troponin, myocarditis may be suspected after normal angiography. Aims To analyse cardiac magnetic resonance (CMR) findings in patients with a provisional diagnosis of acute coronary syndrome (ACS) in whom acute myocarditis was subsequently considered more likely. Methods and results 79 patients referred for CMR following an admission with presumed ACS and raised serum troponin in whom no culprit lesion was detected were studied. 13% had unrecognised myocardial infarction and 6% takotsubo cardiomyopathy. The remainder (81%) were diagnosed with myocarditis. Mean age was 45615 years and 70% were male. Left ventricular ejection fraction (EF) was 58610%; myocardial oedema was detected in 58%. A myocarditic pattern of late gadolinium enhancement (LGE) was detected in 92%. Abnormalities were detected more frequently in scans performed within 2 weeks of symptom onset: oedema in 81% vs 11% (p<0.0005), and LGE in 100% vs 76% (p<0.005). In 20 patients with both an acute (<2 weeks) and convalescent scan (>3 weeks), oedema decreased from 84% to 39% (p<0.01) and LGE from 5.6 to 3.0 segments (p¼0.005). Three patients presented with sustained ventricular tachycardia, another died suddenly 4 days after admission and one resuscitated 7 weeks following presentation. All 5 patients had preserved EF. Conclusions Our study emphasises the importance of access to CMR for heart attack centres. If myocarditis is suspected, CMR scanning should be performed within 14 days. Myocarditis should not be regarded as benign, even when EF is preserved.

Amyloid arthropathy in patients undergoing periodical haemodialysis for chronic renal failure: a new complication.

Seven patients (five male and two female) with chronic renal failure (CRF) treated by periodical haemodialysis presented with swelling and effusion of more than three months' duration in knees (four bilateral), shoulders (two, one of them bilateral), elbow (one), and ankle (one). Four had a carpal tunnel syndrome both clinically and electromyographically (three bilateral). All patients had hyperparathyroidism secondary to their CRF, which was not due to amyloidosis in any of them. The dialysis duration period varied from five to 14 years, with an average of 8.6 years. Amyloid deposits (Congo red positive areas with green birefringence under polarising microscopy) were shown in six of the seven synovial biopsy specimens of the knee, in five of the sediments of the synovial fluids, and in specimens removed during carpal tunnel syndrome surgery. No amyloid was found in the biopsy specimen of abdominal fat of six of the patients. The finding of amyloid only in the synovial membrane and fluid, and carpal tunnel, its absence in abdominal fat, and the lack of other manifestations of generalised amyloidosis (cardiomyopathy, malabsorption syndrome, macroglossia, etc.) and of Bence Jones myeloma (protein immunoelectrophoresis normal) raises the possibility that this is a form of amyloidosis which is peculiar to CRF treated by periodical haemodialysis.

Defective tumor necrosis factor-alpha-dependent control of astrocyte glutamate release in a transgenic mouse model of Alzheimer disease.

The cytokine tumor necrosis factor-alpha (TNFalpha) induces Ca2+-dependent glutamate release from astrocytes via the downstream action of prostaglandin (PG) E2. By this process, astrocytes may participate in intercellular communication and neuromodulation. Acute inflammation in vitro, induced by adding reactive microglia to astrocyte cultures, enhances TNFalpha production and amplifies glutamate release, switching the pathway into a neurodamaging cascade (Bezzi, P., Domercq, M., Brambilla, L., Galli, R., Schols, D., De Clercq, E., Vescovi, A., Bagetta, G., Kollias, G., Meldolesi, J., and Volterra, A. (2001) Nat. Neurosci. 4, 702-710). Because glial inflammation is a component of Alzheimer disease (AD) and TNFalpha is overexpressed in AD brains, we investigated possible alterations of the cytokine-dependent pathway in PDAPP mice, a transgenic model of AD. Glutamate release was measured in acute hippocampal and cerebellar slices from mice at early (4-month-old) and late (12-month-old) disease stages in comparison with age-matched controls. Surprisingly, TNFalpha-evoked glutamate release, normal in 4-month-old PDAPP mice, was dramatically reduced in the hippocampus of 12-month-old animals. This defect correlated with the presence of numerous beta-amyloid deposits and hypertrophic astrocytes. In contrast, release was normal in cerebellum, a region devoid of beta-amyloid deposition and astrocytosis. The Ca2+-dependent process by which TNFalpha evokes glutamate release in acute slices is distinct from synaptic release and displays properties identical to those observed in cultured astrocytes, notably PG dependence. However, prostaglandin E2 induced normal glutamate release responses in 12-month-old PDAPP mice, suggesting that the pathology-associated defect involves the TNFalpha-dependent control of secretion rather than the secretory process itself. Reduced expression of DENN/MADD, a mediator of TNFalpha-PG coupling, might account for the defect. Alteration of this neuromodulatory astrocytic pathway is described here for the first time in relation to Alzheimer disease.

Lytic lesions of the femoral neck in rheumatoid arthritis simulating pigmented villonodular synovitis or malignancy

Large lytic lesions, relatively asymptomatic, involving the femoral neck and the base of the head are described in two patients suffering from a classical seropositive rheumatoid arthritis. Histological examination failed to reveal signs of malignancy, infection or pigmented villonodular synovitis. There were no rheumatoid nodules but a chronic hypertrophic villous synovitis was found. Rheumatoid synovium may invade the superior extremity of the femur; this fact is important in the differential diagnosis of destructive lesions of the femoral neck in RA.