Sandra Voss

Abnormalities in intracellular Ca2+ regulation contribute to the pathomechanism of Tako-Tsubo cardiomyopathy

AIMS The Tako-Tsubo cardiomyopathy (TTC) is characterized by a transient contractile dysfunction that has been assigned to excessive catecholamine levels after episodes of severe emotional or physical stress. Several studies have indicated that beta-adrenoceptor stimulation is associated with alteration in gene expression of Ca(2+)-regulatory proteins. Thus, the present study investigated the gene expression of crucial proteins [sarcoplasmic Ca(2+) ATPase (SERCA2a), sarcolipin (SLN), phospholamban (PLN), ryanodine receptor (RyR2), and sodium-calcium exchanger (NCX)] involved in the Ca(2+)-regulating system in TTC. METHODS AND RESULTS In 10 consecutive patients, TTC was diagnosed by coronary angiography, ventriculography, and echocardiography. Endomyocardial biopsies were taken during the phase of severely impaired left ventricular (LV) function and after functional recovery. Non-diseased LV tissue from three donor hearts not used for transplantation served as healthy controls. Expression levels of Ca(2+)-regulatory proteins were analysed by means of real-time PCR, western blot, and immunohistochemistry. SLN, predominantly expressed in the atrial component, showed a remarkable ventricular expression in TTC patients. Gene expression of SERCA2a was significantly down-regulated. Conversely, PLN/SERCA2a ratio was increased. For PLN, dephosphorylation was documented using western blot and immunostaining of PLN-Ser(16) and PLN-Thr(17). No changes could be documented for NCX and RyR2. CONCLUSION In TTC, ventricular expression of SLN and dephosphorylation of PLN potentially result in a reduced SERCA2a activity and its Ca(2+) affinity. Thus, the TTC is associated with specific alteration of Ca(2+)-handling proteins, which might be crucial for contractile dysfunction.

Immunohistological basis of the late gadolinium enhancement phenomenon in tako-tsubo cardiomyopathy

AIMS Tako-tsubo cardiomyopathy is characterized by transient contractile dysfunction after emotional or physical stress. Only few patients show late gadolinium enhancement (LGE) in cardiovascular magnetic resonance imaging (MRI). It was the purpose of this study to elucidate the histological basis of this phenomenon. METHODS AND RESULTS The study included 15 patients. Tako-tsubo cardiomyopathy was diagnosed by coronary angiography and ventriculography. Cardiac MRI was performed within 24 h of admission. Endomyocardial biopsies were taken during the acute phase and after recovery. The content of fibrosis was determined by immunohistochemical staining of collagen-1. In the acute phase, cardiac MRI revealed LGE in five patients. This was completely reversed at follow-up [14, inter-quartile range (IQR) 11-14.5 days]. All patients showed a significant increase of collagen-1 compared with control tissue. Moreover, the amount of collagen-1 was significantly higher in LGE positive patients (LGE positive: 18.84, IQR 13.82-19.75 AU/microm(2); LGE negative: 7.57, IQR 5.41-9.19 AU/microm(2), P = 0.001). The presence of LGE was not associated with poorer left ventricular function. CONCLUSION The presence of LGE cannot rule out tako-tsubo cardiomyopathy. Instead it defines a special subgroup of patients with a disproportionate increase of extracellular matrix.

Release Kinetics of Circulating Muscle-Enriched MicroRNAs in Patients Undergoing Transcoronary Ablation of Septal Hypertrophy

OBJECTIVES This study sought to evaluate exact release kinetics of microRNAs (miRNAs) in acute myocardial infarction (AMI). BACKGROUND miRNAs may be useful as novel biomarkers in patients with cardiovascular disease, although it is difficult to establish the detailed release kinetics of miRNAs in patients with AMI. METHODS We analyzed the release kinetics of circulating cardiac-specific (miR-21, miR-208a) and muscle-enriched (miR-1, miR-133a) miRNAs using the TaqMan polymerase chain reaction in patients with hypertrophic obstructive cardiomyopathy who were undergoing transcoronary ablation of septal hypertrophy (TASH), a procedure mimicking AMI. Consecutive patients (n = 21) undergoing TASH were included. Serum samples were collected prior to and at 15, 30, 45, 60, 75, 90, and 105 min and 2, 4, 8, and 24 h after TASH. RESULTS Circulating concentrations of miR-1 were significantly increased (>3-fold; p = 0.01) after 15 min, with a peak after 75 min (>60-fold; p < 0.001). The miR-21 concentrations were not increased at any time point. Concentrations of miR-133a were significantly increased at 15 min (2.9-fold; p < 0.001) and reached a plateau between 75 and 480 min (>50-fold change). The miR-208a concentrations were elevated at 105 min (>2-fold; p = 0.01), without a further increase. CONCLUSIONS miR-1, miR-133a, and miR-208a were continuously increased during the first 4 h after the induction of MI. In particular, miR-1 and miR-133a were significantly increased at early time points. These results demonstrate the release kinetics of miRNAs, which are helpful for developing their potential use as biomarkers in patients with acute coronary syndromes.

Activated cell survival cascade protects cardiomyocytes from cell death in Tako-Tsubo cardiomyopathy

Tako‐Tsubo cardiomyopathy (TTC) is characterized by rapid regeneration of contractile dysfunction. From recent studies it is known that excessive catecholamine levels due to emotional or physical stress might play a central role. After sympathetic activation, the PIK3/AKT pathway is a key regulator of many cellular responses, including cytoprotective effects. Thus, the purpose of this study was to investigate whether the PIK3/AKT pathway plays a pivotal role in TTC.

Osteoglycin Prevents Cardiac Dilatation and Dysfunction After Myocardial Infarction Through Infarct Collagen Strengthening

Rationale: To maintain cardiac mechanical and structural integrity after an ischemic insult, profound alterations occur within the extracellular matrix. Osteoglycin is a small leucine-rich proteoglycan previously described as a marker of cardiac hypertrophy. Objective: To establish whether osteoglycin may play a role in cardiac integrity and function after myocardial infarction (MI). Methods and Results: Osteoglycin expression is associated with collagen deposition and scar formation in mouse and human MI. Absence of osteoglycin in mice resulted in significantly increased rupture-related mortality with tissue disruption, intramyocardial bleeding, and increased cardiac dysfunction, despite equal infarct sizes. Surviving osteoglycin null mice had greater infarct expansion in comparison with wild-type mice because of impaired collagen fibrillogenesis and maturation in the infarcts as revealed by electron microscopy and collagen polarization. Absence of osteoglycin did not affect cardiomyocyte hypertrophy in the remodeling remote myocardium. In cultured fibroblasts, osteoglycin knockdown or supplementation did not alter transforming growth factor-&bgr; signaling. Adenoviral overexpression of osteoglycin in wild-type mice significantly improved collagen quality, thereby blunting cardiac dilatation and dysfunction after MI. In osteoglycin null mice, adenoviral overexpression of osteoglycin was unable to prevent rupture-related mortality because of insufficiently restoring osteoglycin protein levels in the heart. Finally, circulating osteoglycin levels in patients with heart failure were significantly increased in the patients with a previous history of MI compared with those with nonischemic heart failure and correlated with survival, left ventricular volumes, and other markers of fibrosis. Conclusions: Increased osteoglycin expression in the infarct scar promotes proper collagen maturation and protects against cardiac disruption and adverse remodeling after MI. In human heart failure, osteoglycin is a promising biomarker for ischemic heart failure.

Release Kinetics of Copeptin in Patients Undergoing Transcoronary Ablation of Septal Hypertrophy

BACKGROUND The release kinetics of copeptin in patients with acute myocardial infarction (AMI) have been difficult to establish. METHODS We analyzed the release kinetics of copeptin in patients with hypertrophic obstructive cardiomyopathy undergoing transcoronary ablation of septal hypertrophy (TASH) as a model of AMI. We included 21 consecutive patients who underwent TASH. Blood samples were collected before and at 15, 30, 45, 60, 75, 90, and 105 min, and at 2, 4, 8, and 24 h after TASH. Serum copeptin was quantified by a sandwich immunoluminometric assay. RESULTS All patients had copeptin concentrations below the 99th percentile at baseline. The median copeptin concentration was significantly increased at 30 min [16.0 pmol/L; interquartile range (IQR), 13.4-20.2 pmol/L], compared with the median baseline concentration (6.6 pmol/L; IQR, 5.3-8.3 pmol/L; P = 0.002). The copeptin concentration peaked 90 min after induction of myocardial infarction and returned to baseline concentrations (median, 8.2 pmol/L; IQR, 6.3-10.1) after 24 h, compared with the above baseline values (P = 0.06). Serum creatine kinase (CK) activities were significantly increased above baseline values by 1 day after TASH [median maximal postprocedural CK activity, 935.0 U/L (IQR, 545.5-1115.0 U/L); median baseline CK activity, 80.0 U/L (IQR, 63.5-109.0 U/L); P < 0.001]. CONCLUSIONS Our results provide additional evidence that early rule-out of suspected AMI is possible by using the copeptin concentration in combination with cardiac troponin T.

Calcium-dependent signalling is essential during collateral growth in the pig hind limb-ischemia model

We investigated the effect of pharmacological activation of the Ca(2+)-channel transient receptor potential cation channel, subfamily V, member 4 (TRPV4) on collateral growth in a pig hind limb-ischemia model thereby identifying subcellular mechanisms. Domestic pigs received femoral artery ligature and were randomly assigned to one of the following groups (each n=6): (1) 4alpha-phorbol 12,13-didecanoate (4alphaPDD) treatment; (2) treatment with an arterio-venous shunt (AV-shunt) distal to the occlusion; or (3) implantation of NaCl-filled minipump. Six sham-operated pigs acted as controls. Aortic and peripheral mean arterial pressure (MAP) measurements were performed to assess the collateral flow index (CFI). Tissue was isolated from M. quadriceps for immunohistochemistry and from isolated collateral arteries for quantitative real time PCR (qRT-PCR). Shortly after ligature the CFI dropped from 0.96+/-0.02 to 0.21+/-0.02 in all ligature-treated groups. In ligature-only-treated pigs CFI increased to 0.56+/-0.03 after 7days. Treatment with 4alphaPDD led to an enhancement of CFI compared with ligature alone (0.73+/-0.03). CD31-staining showed improved arteriolar density. Increased Ki67 staining in collaterals indicated proliferation. qRT-PCR and Western blot analysis showed upregulation or modulation of Ca(2+)-dependent transcription factors nuclear factor of activated T-cells, cytoplasmic, calcineurin-dependent 1 (NFATc1), Kv channel interacting protein 3, calsenilin (KCNIP3/CSEN/DREAM), and myocyte enhancer factor 2C (MEF2C) in 4alphaPDD- and AV-shunt-treated pigs compared with controls. Improved CFI after 4alphaPDD treatment identifies TRPV4 as an initial fluid shear-stress sensor and collateral remodelling and growth trigger. Subcellularly, modulation of Ca(2+)-dependent transcription factors indicates a pivotal role for Ca(2+)-signalling during arteriogenesis.

Release Kinetics of Inflammatory Biomarkers in a Clinical Model of Acute Myocardial Infarction

RATIONALE Inflammation in the setting of acute myocardial infarction (MI) has been linked to risk stratification; however, the release kinetics of inflammatory biomarkers in patients with acute MI has been difficult to establish. OBJECTIVE The aim of this study was to determine the kinetics of changes in the levels of several biomarkers specifically linked to inflammation after transcoronary ablation of septal hypertrophy, a procedure that mimics acute MI. METHODS AND RESULTS We analyzed release kinetics of C-reactive protein, high-sensitivity C-reactive protein, interleukin-6, soluble CD40 ligand, and peripheral blood leukocyte subsets in patients (n=21) undergoing transcoronary ablation of septal hypertrophy. Blood samples were collected before transcoronary ablation of septal hypertrophy and at various times after transcoronary ablation of septal hypertrophy. Serum levels of C-reactive protein were increased at 24 hours (1.0 mg/dL [interquartile range [IQR], 0.7-1.75] versus 0.2 mg/dL [IQR, 0.1-1.05] at baseline [BL]; P<0.001), whereas high-sensitivity C-reactive protein increased as early as 8 hours (2.68 mg/L [IQR, 1.23-11.80] versus 2.17 mg/L [IQR, 1.15-5.06] at BL; P=0.002). Interleukin-6 was significantly increased at 45 minutes (2.59 pg/mL [IQR, 1.69-5.0] versus 1.5 pg/mL [IQR, 1.5-2.21] at BL; P=0.002), and soluble CD40 ligand was significantly decreased at 60 minutes (801.6 pg/mL [IQR, 675.0-1653.5] versus 1750.0 pg/mL [IQR, 1151.0-2783.0] at BL; P=0.016). Elevated counts of polymorphonuclear neutrophils were detectable at 15 minutes, with a significant increase at 2 hours (6415 cells/μL [IQR, 5288-7827] versus 4697 cells/μL [IQR, 2892-5620] at BL; P=0.004). Significant monocytosis was observed at 24 hours (729 cells/μL [IQR, 584-1344] versus 523 cells/μL [IQR, 369-701] at BL; P=0.015). CONCLUSIONS Interleukin-6 and neutrophil granulocytes showed a continuous rise at all prespecified time points after induction of MI. Our results provide valuable additional evidence of the diagnostic value of inflammatory biomarkers in the setting of early acute MI.

New potential diagnostic biomarkers for pulmonary hypertension

This study aimed to determine whether the vascular endothelial growth factor (VEGF) family members soluble VEGF receptor 1 (also called soluble fms-like tyrosine kinase 1 (sFlt-1)) and placental growth factor (PlGF) could be used as biomarkers for pulmonary hypertension (PH). Consecutive patients undergoing right heart catheterisation were enrolled (those with mean pulmonary arterial pressure ≥25 mmHg were classed as having PH; those with mean pulmonary arterial pressure <25 mmHg acted as non-PH controls). Plasma from the time of PH diagnosis was analysed for PlGF and sFlt-1 using enzyme immunoassays. In total, 247 patients with PH were enrolled: 62 with idiopathic pulmonary arterial hypertension (IPAH), 14 with associated pulmonary arterial hypertension (APAH), 21 with collagen vascular disease (CVD), 26 with pulmonary venous hypertension, 67 with lung disease-associated PH and 57 with chronic thromboembolic PH. The non-PH control group consisted of 40 patients. sFlt-1 plasma levels were significantly higher in patients with IPAH, APAH, CVD and lung disease-associated PH versus controls; PlGF levels were significantly higher in all PH groups versus controls. The combination of sFlt-1 and PlGF resulted in a sensitivity of 83.7% with specificity of 100% for pulmonary arterial hypertension. There was no association between sFlt-1 or PlGF and haemodynamic parameters, 6-min walking distance or survival. In summary, PlGF and sFlt-1 are promising diagnostic biomarkers for PH. This study shows a high potential for VEGF family members as diagnostic biomarkers for pulmonary hypertension http://ow.ly/P5GCW

Molecular basis of disturbed extracellular matrix homeostasis in stress cardiomyopathy

Sebastian Szardien , Helge Mollmann , Matthias Willmer , Christoph Liebetrau , Sandra Voss , Christian Troidl , Jedrzej Hoffmann , Johannes Rixe , Albrecht Elsasser , Christian W. Hamm , Holger M. Nef a,b,c,⁎ a Kerckhoff Heart Center, Department of Cardiology, D-61231 Bad Nauheim, Germany b Department of Experimental Cardiology, Franz-Groedel-Institute of the Kerckhoff Heart Center, D-61231 Bad Nauheim, Germany c University of Giessen, Medical Clinic I, Department of Cardiology, D-39392 Giessen, Germany d Department of Cardiology, Klinikum Oldenburg, D-26121 Oldenburg, Germany