Janine Pöss

Physical Exercise Prevents Cellular Senescence in Circulating Leukocytes and in the Vessel Wall

Background— The underlying molecular mechanisms of the vasculoprotective effects of physical exercise are incompletely understood. Telomere erosion is a central component of aging, and telomere-associated proteins regulate cellular senescence and survival. This study examines the effects of exercising on vascular telomere biology and endothelial apoptosis in mice and the effects of long-term endurance training on telomere biology in humans. Methods and Results— C57/Bl6 mice were randomized to voluntary running or no running wheel conditions for 3 weeks. Exercise upregulated telomerase activity in the thoracic aorta and in circulating mononuclear cells compared with sedentary controls, increased vascular expression of telomere repeat-binding factor 2 and Ku70, and reduced the expression of vascular apoptosis regulators such as cell-cycle–checkpoint kinase 2, p16, and p53. Mice preconditioned by voluntary running exhibited a marked reduction in lipopolysaccharide-induced aortic endothelial apoptosis. Transgenic mouse studies showed that endothelial nitric oxide synthase and telomerase reverse transcriptase synergize to confer endothelial stress resistance after physical activity. To test the significance of these data in humans, telomere biology in circulating leukocytes of young and middle-aged track and field athletes was analyzed. Peripheral blood leukocytes isolated from endurance athletes showed increased telomerase activity, expression of telomere-stabilizing proteins, and downregulation of cell-cycle inhibitors compared with untrained individuals. Long-term endurance training was associated with reduced leukocyte telomere erosion compared with untrained controls. Conclusions— Physical activity regulates telomere-stabilizing proteins in mice and in humans and thereby protects from stress-induced vascular apoptosis.

Renal denervation suppresses ventricular arrhythmias during acute ventricular ischemia in pigs

BACKGROUND Increased sympathetic activation during acute ventricular ischemia is involved in the occurrence of life-threatening arrhythmias. OBJECTIVE To test the effect of sympathetic inhibition by renal denervation (RDN) on ventricular ischemia/reperfusion arrhythmias. METHODS Anesthetized pigs, randomized to RDN or SHAM treatment, were subjected to 20 minutes of left anterior descending coronary artery (LAD) occlusion followed by reperfusion. Infarct size, hemodynamics, premature ventricular contractions, and spontaneous ventricular tachyarrhythmias were analyzed. Monophasic action potentials were recorded with an epicardial probe at the ischemic area. RESULTS Ventricular ischemia resulted in an acute reduction of blood pressure (-29%) and peak left ventricular pressure rise (-40%), which were not significantly affected by RDN. However, elevation of left ventricular end-diastolic pressure (LVEDP) during LAD ligation was attenuated by RDN (ΔLVEDP: +1.8 ± 0.6 mm Hg vs +9.7 ± 1 mm Hg in the SHAM group; P = .046). Infarct size was not affected by RDN compared to SHAM. RDN significantly reduced spontaneous ventricular extrabeats (160 ± 15/10 min in the RDN group vs 422 ± 36/10 min in the SHAM group; P = .021) without affecting coupling intervals. In 5 of 6 SHAM-treated animals, ventricular fibrillation (VF) occurred during LAD occlusion. By contrast, only 1 of 7 RDN-treated animals experienced VF (P = .029). Beta-receptor blockade by atenolol showed comparable effects. Neither VF nor transient shortening of monophasic action potential duration during reperfusion was inhibited by RDN. CONCLUSIONS RDN reduced the occurrence of ventricular arrhythmias/fibrillation and attenuated the rise in LVEDP during left ventricular ischemia without affecting infarct size, changes in ventricular contractility, blood pressure, and reperfusion arrhythmias. Therefore, RDN may protect from ventricular arrhythmias during ischemic events.

Targeting the Proprotein Convertase Subtilisin/Kexin Type 9 for the Treatment of Dyslipidemia and Atherosclerosis

Hypercholesterolemia is a major risk factor for cardiovascular diseases, increasing the incidence of myocardial infarction and death. Statin-induced lowering of low-density lipoprotein cholesterol (LDL-C) reduces cardiovascular morbidity and mortality. However, many individuals treated with statins do not achieve their target levels of LDL-C, and thus, LDL-associated residual risk remains. Gain-of-function mutations of the proprotein convertase subtilisin/kexin type 9 (PCSK9) are associated with hypercholesterolemia and increased risk of cardiovascular events. Conversely, loss-of-function mutations are linked to low plasma LDL-C levels and a reduction of cardiovascular risk without known unwanted effects on individual health. Experimental studies have revealed that PCSK9 reduces the hepatic uptake of LDL-C by increasing the endosomal and lysosomal degradation of LDL receptors (LDLR). Low intracellular cholesterol levels in response to statin treatment activate the sterol regulatory element-binding protein-2 (SREBP-2), resulting in coexpression of LDLR and PCSK9. Although this self-regulatory mechanism contributes to maintain cholesterol homeostasis preventing excessive cholesterol uptake, it may limit the therapeutic effect of statins. A number of clinical studies have demonstrated that inhibition of PCSK9 alone and in addition to statins potently reduces serum LDL-C concentrations. Moreover, experimental studies indicate that PCSK9 might accelerate atherosclerosis by promoting inflammation, endothelial dysfunction, and hypertension by mechanisms independent of the LDLR. Further research is needed to characterize the potential therapeutic and to rule out unwanted off-target effects of PCSK9 inhibition. In this review we elucidate the role of PCSK9 in lipid homeostasis, highlight the impact of PCSK9 on atherosclerosis, and summarize current therapeutic strategies targeting PCSK9.

Effects of Physical Exercise on Myocardial Telomere- Regulating Proteins, Survival Pathways, and Apoptosis

OBJECTIVES The purpose of this study was to study the underlying molecular mechanisms of the protective cardiac effects of physical exercise. BACKGROUND Telomere-regulating proteins affect cellular senescence, survival, and regeneration. METHODS C57/Bl6 wild-type, endothelial nitric oxide synthase (eNOS)-deficient and telomerase reverse transcriptase (TERT)-deficient mice were randomized to voluntary running or no running wheel conditions (n = 8 to 12 per group). RESULTS Short-term running (21 days) up-regulated cardiac telomerase activity to >2-fold of sedentary controls, increased protein expression of TERT and telomere repeat binding factor (TRF) 2, and reduced expression of the proapoptotic mediators cell-cycle-checkpoint kinase 2 (Chk2), p53, and p16. Myocardial and leukocyte telomere length did not differ between 3-week- and 6-month-old sedentary or running mice, but telomerase activity, TRF2 and TERT expression were persistently increased after 6 months and the expression of Chk2, p53, and p16 remained down-regulated. The exercise-induced changes were absent in both TERT(-/-) and eNOS(-/-) mice. Running increased cardiac expression of insulin-like growth factor (IGF)-1. Treatment with IGF-1 up-regulated myocardial telomerase activity >14-fold and increased the expression of phosphorylated Akt protein kinase and phosphorylated eNOS. To test the physiologic relevance of these exercise-mediated prosurvival pathways, apoptotic cardiomyopathy was induced by treatment with doxorubicin. Up-regulation of telomere-stabilizing proteins by physical exercise in mice reduced doxorubicin-induced p53 expression and potently prevented cardiomyocyte apoptosis in wild-type, but not in TERT(-/-) mice. CONCLUSIONS Long- and short-term voluntary physical exercise up-regulates cardiac telomere-stabilizing proteins and thereby induces antisenescent and protective effects, for example, to prevent doxorubicin-induced cardiomyopathy. These beneficial cardiac effects are mediated by TERT, eNOS, and IGF-1.

Pioglitazone activates aortic telomerase and prevents stress-induced endothelial apoptosis

OBJECTIVE Telomeres and associated proteins are regulators of cellular survival, regeneration and aging. PPAR-γ agonists may mediate vascular effects in addition to insulin sensitizing. We therefore examined whether pioglitazone regulates vascular telomere biology. METHODS AND RESULTS C57/Bl6 mice were randomized to treatment with pioglitazone (20mg/kg i.p. daily) or vehicle for 4 weeks (n = 6-8 per group). Telomere repeat amplification protocols showed a 2-fold increase of aortic telomerase activity in the pioglitazone group. Telomere repeat-binding factor 2 protein and mRNA levels (236%+172% of vehicle) as well as phosphorylation of protein kinase Akt (479% of vehicle) were up-regulated. Western blots demonstrated reduced aortic expression of senescence markers p16, cell-cycle checkpoint kinase 2 and p53. These regulatory mechanisms were independent of acute changes of telomere length. Similar observations were made in mononuclear cells (MNC) from these mice and in cultivated bovine aortic endothelial cells, human MNC and endothelial progenitor cells (EPC). Telomerase activation by pioglitazone in cultivated cells was prevented by Akt inhibitors. To test the functional relevance of the findings, isolated mononuclear cells (MNC) were exposed to H(2)O(2). MNC from pioglitazone-treated mice exhibited reduced apoptosis (AnnexinV-FACS). In vivo, lipopolysaccharide-induced aortic endothelial apoptosis was potently prevented in pioglitazone-treated animals (hairpin oligonucleotide assay). Both, up-regulation of telomere-regulating proteins and prevention of oxidative stress-induced aortic apoptosis, were absent in telomerase reverse transcriptase (TERT)-deficient mice. CONCLUSIONS/INTERPRETATION Pioglitazone treatment up-regulates telomerase activity, telomere-stabilizing proteins and reduces senescence markers in vascular cells. These effects and the reduction of LPS-induced endothelial apoptosis by thiazolidinediones depend on TERT. The findings underscore the important role of telomere-regulating proteins for vascular cell function and survival.

Optimal antagonism of the Renin-Angiotensin-aldosterone system: do we need dual or triple therapy?

The cardiovascular and cardiorenal disease continuum comprises the transition from cardiovascular risk factors to endothelial dysfunction and atherosclerosis, to clinical complications such as myocardial infarction (MI) and stroke, to the development of persistent target-organ damage and, ultimately, to chronic congestive heart failure (CHF), end-stage renal disease or premature death. The renin-angiotensin-aldosterone system (RAAS) is involved in all steps along this pathway, and RAAS blockade with ACE inhibitors or angiotensin AT1-receptor antagonists (angiotensin receptor blockers; ARBs) has turned out to be beneficial for patient outcomes throughout the disease continuum. Both ACE inhibitors and ARBs can prevent or reverse endothelial dysfunction and atherosclerosis, thereby reducing the risk of cardiovascular events. These drugs have further been shown to reduce end-organ damage in the heart, kidneys and brain. Aldosterone antagonists such as spironolactone and eplerenone are increasingly recognized as a third class of RAAS inhibitor with potent risk-reducing properties, especially but not solely with respect to the inhibition of cardiac remodelling and the possible prevention of heart failure.In secondary prevention, head-to-head comparisons of ACE inhibitors and ARBs, such as the recent ONTARGET study, provided evidence that, in addition to better tolerability, ARBs are non-inferior to ACE inhibitors in the prevention of clinical endpoints such as MI and stroke in cardiovascular high-risk patients. However, the combination of both ramipril and telmisartan at the maximally tolerated dosage achieved no further benefits and was associated with more adverse events such as symptomatic hypotension and renal dysfunction. In acute MI complicated by heart failure, the VALIANT trial has shown similar effects of ACE inhibition with captopril and ARB treatment with valsartan, but dual RAAS blockade did not further reduce events. In CHF, meta-analyses of RESOLVD, ValHeFT and CHARM-ADDED have shown that combined RAAS inhibition with an ACE inhibitor and ARB significantly reduced the morbidity endpoint in certain patient subgroups compared with standard therapy. However, in clinical practice, dual RAAS blockade is rarely employed, as seen, for instance, in the CORONA trial. The RALES and EPHESUS trials, investigating the effects of aldosterone blockade on cardiovascular outcomes in CHF patients, revealed that the addition of an aldosterone antagonist to standard heart failure therapy conferred powerful relative risk reductions for both morbidity and mortality. Future studies will elucidate whether this also holds true for patients who are asymptomatic or who have heart failure with preserved ejection fraction.In selected patients with renal disease, several studies have suggested that combined RAAS blockade brings about additional renoprotective antiproteinuric effects independent of blood pressure reduction, and large trials with robust endpoints are underway.In summary, combined therapy with several RAAS inhibitors is not recommended for all patients along the cardiorenovascular continuum. Patients with CHF with incomplete neuroendocrine blockade, as indicated, for example, by repetitive cardiac decompensation or refractory symptoms, might benefit from dual therapy as long as safety issues are well controlled. Finally, novel pharmacological agents such as the direct renin inhibitor aliskiren may provide additional therapeutic tools, but their role has yet to be established.

Total-to-ionized calcium ratio predicts mortality in continuous renal replacement therapy with citrate anticoagulation in critically ill patients.

IntroductionRegional citrate anticoagulation is safe, feasible and increasingly used in critically ill patients on continuous renal replacement therapy (CRRT). However, in patients with hepatic or multi-organ dysfunction, citrate accumulation may lead to an imbalance of calcium homeostasis. The study aimed at evaluating the incidence and prognostic relevance of an increased total to ionized calcium ratio (T/I Ca2+ ratio) and its association to hepatic dysfunction.MethodsWe performed a prospective observational study on n = 208 critically ill patients with acute kidney injury (AKI) and necessity for CRRT with regional citrate anticoagulation (CRRT-citrate) between September 2009 and September 2011. Critical illness was estimated by Simplified Acute Physiology Score II; hepatic function was measured with indocyanine green plasma disappearance rate. After achieving a steady state of calcium homeostasis patients were classified into tertiles according to the T/I Ca2+ ratio (<2.0 versus 2.0 - 2.39 versus ≥2.4).ResultsThe T/I Ca2+ ratio was determined as an independent predictor for 28-day mortality in critically ill patients with AKI on CRRT-citrate confirmed by receiver operating characteristics and multivariate analysis (Area under the curve 0.94 ± 0.02; p<0.001). A T/I Ca2+ ratio ≥2.4 independently predicted a 33.5-fold (p<0.001) increase in 28-day mortality-rate. There was a significant correlation between the T/I Ca2+ ratio and the hepatic clearance (p<0.001) and the severity of critical illness (p<0.001). The efficacy and safety of citrate anticoagulation, determined by blood urea nitrogen, mean filter patency and bleeding episodes, were not significantly different between the tertiles.ConclusionsIn patients on CRRT-citrate T/I Ca2+ ratio is closely related to the clinical outcome and emerged as an independent predictor of 28-day mortality. Larger studies are required to define the cut-off and predictive value for the T/I Ca2+ ratio. This ratio is associated with hepatic and/or multi-organ dysfunction and therefore an important therapeutic target.

Hotlines and clinical trial updates presented at the German Cardiac Society Meeting 2010: FAIR-HF, CIPAMI, LIPSIA-NSTEMI, Handheld-BNP, PEPCAD III, remote ischaemic conditioning, CERTIFY, PreSCD-II, German Myocardial Infarction Registry, DiaRegis

This article summarizes the results of a number of clinical trials and registries in the field of cardiovascular medicine which were presented during the Hotline Sessions at the annual meeting of the German Cardiac Society, held in Mannheim, Germany, from 8th to 10th April 2010. The data were presented by leading experts in the field with relevant positions in the trials. It is important to note that unpublished reports should be considered as preliminary data, as the analysis may change in the final publications. The comprehensive summaries have been generated from the oral presentation and should provide the readers with the most comprehensive information on diagnostic and therapeutic development in cardiovascular medicine similar as previously reported (Maier et al. in Clin Res Cardiol 98:345–352, 2009; 98:413–419, 2009).

FGF-23 is associated with increased disease severity and early mortality in cardiogenic shock

Background: Despite the increased use of percutaneous interventions, infarction-related cardiogenic shock (CS) is still associated with high mortality. Biomarkers might be helpful to identify patients at risk, and point towards novel therapeutic strategies in CS. The phosphaturic hormone fibroblast growth factor 23 (FGF-23) has recently been introduced as a predictor for mortality in patients with chronic systolic heart failure. However, its predictive role in CS has not been investigated so far. Methods and results: FGF-23 was measured in 51 patients with CS. Eighteen patients with uncomplicated acute myocardial infarction (AMI) and 940 patients with stable coronary artery disease (CAD) undergoing elective coronary angiography included in a previous study served as control groups. Compared with patients with stable CAD, FGF-23 was profoundly elevated in patients with CS, but not in patients with uncomplicated AMI (CAD: 131.1±9.5; AMI: 175.3 ±57.2; CS: 1684.4±591.7 rU/ml, p<0.0001 CS vs. CAD). In patients with CS, FGF-23 correlated significantly with the SAPS II score (r=0.461, p=0.0003) and NT-pro BNP levels (r=0.489, p=0.001). Patients were stratified as “survivors” and “non-survivors” according to their 28-day mortality. The overall 28-day-mortality-rate was 37%. Non-survivors of CS showed significantly higher FGF-23 levels compared with survivors (3260.1±1514.7 vs. 847.9±182.4 rU/ml, p=0.028). In the ROC curve analysis, FGF-23 levels predicted 28-day mortality (area under the curve (AUC) 0.686, p=0.028), and FGF-23 level of 1180 rU/ml was identified as optimal cut-off value. In a multivariate Cox proportional hazard model adjusted for gender, blood pressure, ejection fraction and levels of creatine kinase, FGF-23 levels above 1180 rU/ml significantly predicted 28-day mortality (hazard ratio (HR) 2.74, 95% CI 1.01-7.04, p=0.037). Conclusion: In CS, a tremendous increase in FGF-23 occurs, and high levels of FGF-23 are associated with poor outcome.

Effects of Renal Sympathetic Denervation on Exercise Blood Pressure, Heart Rate, and Capacity in Patients With Resistant Hypertension

Renal denervation reduces office blood pressure in patients with resistant hypertension. This study investigated the effects of renal denervation on blood pressure, heart rate, and chronotropic index at rest, during exercise, and at recovery in 60 patients (renal denervation group=50, control group=10) with resistant hypertension using a standardized bicycle exercise test protocol performed 6 and 12 months after renal denervation. After renal denervation, exercise blood pressure at rest was reduced from 158±3/90±2 to 141±3/84±4 mm Hg (P<0.001 for systolic blood pressure/P=0.007 for diastolic blood pressure) after 6 months and 139±3/83±4 mm Hg (P<0.001/P=0.022) after 12 months. Exercise blood pressure tended to be lower at all stages of exercise at 6- and 12-month follow-up in patients undergoing renal denervation, although reaching statistical significance only at mild-to-moderate exercise levels (75–100 W). At recovery after 1 minute, blood pressure decreased from 201±4/95±2 to 177±4/88±2 (P<0.001/P=0.066) and 188±6/86±2 mm Hg (P=0.059/P=0.01) after 6 and 12 months, respectively. Heart rate was reduced after renal denervation from 71±3 bpm at rest, 128±5 bpm at maximum workload, and 96±5 bpm at recovery after 1 minute to 66±2 (P<0.001), 115±5 (P=0.107), and 89±3 bpm (P=0.008) after 6 months and to 69±3 (P=0.092), 122±7 (P=0.01), and 93±4 bpm (P=0.032) after 12 months. Mean exercise time increased from 6.59±0.33 to 8.4±0.32 (P<0.001) and 9.0±0.41 minutes (P=0.008), and mean workload increased from 93±2 to 100±2 (P<0.001) and 101±3 W (P=0.007) at 6- and 12-month follow-up, respectively. No changes were observed in the control group. In conclusion, renal denervation reduced blood pressure and heart rate during exercise, improved mean workload, and increased exercise time without impairing chronotropic competence.