Cardiological parameters predict mortality and cardiotoxicity in oncological patients

AIMS

Oncological patients suspected at risk for cardiotoxicity are recommended to undergo intensified cardiological surveillance. We investigated the value of cardiac biomarkers and patient-related risk factors [age, cardiovascular risk factors (CVRFs), and cardiac function] for the prediction of all-cause mortality (ACM) and the development of cardiotoxicity.

METHODS AND RESULTS

Between January 2016 and December 2020, patients with oncological diseases admitted to the Cardio-Oncology Unit at the Heidelberg University Hospital were included. They were evaluated by medical history, physical examination, 12-lead electrocardiogram, 2D echocardiography, and cardiac biomarkers [high-sensitivity cardiac troponin T (hs-cTnT) and N-terminal pro-brain natriuretic peptide (NT-proBNP)]. The primary endpoint was defined as ACM and the secondary endpoint was defined as cardiotoxicity, as defined by the European Society of Cardiology. Of the 1971 patients enrolled, the primary endpoint was reached by 490 patients (25.7%) with a median of 363.5 [interquartile range (IQR) 121.8, 522.5] days after presentation. Hs-cTnT of ≥ 7 ng/L [odds ratio (OR) 1.82, P < 0.001] and NT-proBNP (OR 1.98, P < 0.001) were independent predictors of ACM, while reduced left ventricular ejection fraction was not associated with increased ACM (P = 0.85). The secondary endpoint was reached by 182 patients (9.2%) with a median of 793.5 [IQR 411.2, 1165.0] days. Patients with multiple CVRFs (defined as high risk, n = 886) had an increased risk of cardiotoxicity (n = 100/886, 11.3%; hazard ratio 1.57, P = 0.004). They showed elevated baseline values of hs-cTnT (OR 1.60, P = 0.006) and NT-proBNP (OR 4.00, P < 0.001) and had an increased risk of ACM (OR 1.43, P = 0.031).

CONCLUSIONS

In cancer patients, CVRF accumulation predicts cardiotoxicity whereas elevated hs-cTnT or NT-proBNP levels are associated with ACM. Accordingly, less intensive surveillance protocols may be warranted in patients with low cardiac biomarker levels and absence of CVRFs.

Thymus alterations and susceptibility to immune checkpoint inhibitor myocarditis

Immune checkpoint inhibitors (ICI) have transformed the therapeutic landscape in oncology. However, ICI can induce uncommon life-threatening autoimmune T-cell-mediated myotoxicities, including myocarditis and myositis. The thymus plays a critical role in T cell maturation. Here we demonstrate that thymic alterations are associated with increased incidence and severity of ICI myotoxicities. First, using the international pharmacovigilance database VigiBase, the Assistance Publique Hôpitaux de Paris-Sorbonne University data warehouse (Paris, France) and a meta-analysis of clinical trials, we show that ICI treatment of thymic epithelial tumors (TET, and particularly thymoma) was more frequently associated with ICI myotoxicities than other ICI-treated cancers. Second, in an international ICI myocarditis registry, we established that myocarditis occurred earlier after ICI initiation in patients with TET (including active or prior history of TET) compared to other cancers and was more severe in terms of life-threatening arrythmias and concurrent myositis, leading to respiratory muscle failure and death. Lastly, we show that presence of anti-acetylcholine-receptor antibodies (a biological proxy of thymic-associated autoimmunity) was more prevalent in patients with ICI myocarditis than in ICI-treated control patients. Altogether, our results highlight that thymic alterations are associated with incidence and seriousness of ICI myotoxicities. Clinico-radio-biological workup evaluating the thymus may help in predicting ICI myotoxicities.

Cardiomuscular Biomarkers in the Diagnosis and Prognostication of Immune Checkpoint Inhibitor Myocarditis

BACKGROUND

Immune checkpoint inhibitors (ICIs) are approved for multiple cancers but can result in ICI-associated myocarditis, an infrequent but life-threatening condition. Elevations in cardiac biomarkers, specifically troponin-I (cTnI), troponin-T (cTnT), and creatine kinase (CK), are used for diagnosis. However, the association between temporal elevations of these biomarkers with disease trajectory and outcomes has not been established.

METHODS

We analyzed the diagnostic accuracy and prognostic performances of cTnI, cTnT, and CK in patients with ICI myocarditis (n=60) through 1-year follow-up in 2 cardio-oncology units (APHP Sorbonne, Paris, France and Heidelberg, Germany). A total of 1751 (1 cTnT assay type), 920 (4 cTnI assay types), and 1191 CK sampling time points were available. Major adverse cardiomyotoxic events (MACE) were defined as heart failure, ventricular arrhythmia, atrioventricular or sinus block requiring pacemaker, respiratory muscle failure requiring mechanical ventilation, and sudden cardiac death. Diagnostic performance of cTnI and cTnT was also assessed in an international ICI myocarditis registry.

RESULTS

Within 72 hours of admission, cTnT, cTnI, and CK were increased compared with upper reference limits (URLs) in 56 of 57 (98%), 37 of 42 ([88%] P=0.03 versus cTnT), and 43 of 57 ([75%] P<0.001 versus cTnT), respectively. This increased rate of positivity for cTnT (93%) versus cTnI ([64%] P<0.001) on admission was confirmed in 87 independent cases from an international registry. In the Franco-German cohort, 24 of 60 (40%) patients developed ≥1 MACE (total, 52; median time to first MACE, 5 [interquartile range, 2-16] days). The highest value of cTnT:URL within the first 72 hours of admission performed best in terms of association with MACE within 90 days (area under the curve, 0.84) than CK:URL (area under the curve, 0.70). A cTnT:URL ≥32 within 72 hours of admission was the best cut-off associated with MACE within 90 days (hazard ratio, 11.1 [95% CI, 3.2-38.0]; P<0.001), after adjustment for age and sex. cTnT was increased in all patients within 72 hours of the first MACE (23 of 23 [100%]), whereas cTnI and CK values were less than the URL in 2 of 19 (11%) and 6 of 22 (27%) of patients (P<0.001), respectively.

CONCLUSIONS

cTnT is associated with MACE and is sensitive for diagnosis and surveillance in patients with ICI myocarditis. A cTnT:URL ratio <32 within 72 hours of diagnosis is associated with a subgroup at low risk for MACE. Potential differences in diagnostic and prognostic performances between cTnT and cTnI as a function of the assays used deserve further evaluation in ICI myocarditis.

Patient-reported ability to walk 4 m and to wash: New clinical endpoints and predictors of survival in patients with pre-terminal cancer

BACKGROUND

Maintaining the ability to perform self-care is a critical goal in patients with cancer. We assessed whether the patient-reported ability to walk 4 m and wash oneself predict survival in patients with pre-terminal cancer.

METHODS

We performed a prospective observational study on 169 consecutive hospitalized patients with cancer (52% female, 64 ± 12 years) and an estimated 1-12 months prognosis at an academic, inpatient palliative care unit. Patients answered functional questions for 'today', 'last week', and 'last month', performed patient-reported outcomes (PROs), and physical function assessments.

RESULTS

Ninety-two (54%) patients reported the ability to independently walk 4 m and 100 (59%) to wash 'today'. The median number of days patients reported the ability to walk 4 m and wash were 6 (IQR 0-7) and 7 (0-7) days ('last week'); and 27 (5-30) and 26 (10-30) days ('last month'). In the last week, 32% of patients were unable to walk 4 m on every day and 10% could walk on 1-3 days; 30% were unable to wash on every day and 10% could wash on 1-3 days. In the last months, 14% of patients were unable to walk 4 m on every day and 10% could only walk on 1-10 days; 12% were unable to wash on every day and 11% could wash on 1-10 days. In patients who could walk 'today' average 4 m gait speed was 0.78 ± 0.28 m/s. Patients who reported impaired walking and washing experienced more symptoms (dyspnoea, exertion, and oedema) and decreased physical function (higher Eastern Cooperative Oncology Group Performance Status, and lower Karnofsky Performance Status and hand-grip strength [unable vs. able to walk 'today': 205 ± 87 vs. 252 ± 78 Newton, P = 0.001; unable vs. able to wash 'today': 204 ± 86 vs. 250 ± 80 Newton, P = 0.001]). During the 27 months of observation, 152 (90%) patients died (median survival 46 days). In multivariable Cox proportional hazards regression analyses, all tested parameters were independent predictors of survival: walking 4 m 'today' (HR 0.63, P = 0.015), 'last week' (per 1 day: HR 0.93, P = 0.011), 'last month' (per 1 day: HR 0.98, P = 0.012), 4 m gait speed (per 1 m/s: HR 0.45, P = 0.002), and washing 'today' (HR 0.67, P = 0.024), 'last week (per 1 day HR 0.94, p=0.019), and 'last month' (per 1 day HR 0.99, P = 0.040). Patients unable to walk and wash experienced the shortest survival and most reduced functional status.

CONCLUSIONS

In patients with pre-terminal cancer, the self-reported ability to walk 4 m and wash were independent predictors of survival and associated with decreased functional status.

Effect of SARS-CoV-2 mRNA-Vaccine on the Induction of Myocarditis in Different Murine Animal Models

In the course of the SARS-CoV-2 pandemic, vaccination safety and risk factors of SARS-CoV-2 mRNA-vaccines were under consideration after case reports of vaccine-related side effects, such as myocarditis, which were mostly described in young men. However, there is almost no data on the risk and safety of vaccination, especially in patients who are already diagnosed with acute/chronic (autoimmune) myocarditis from other causes, such as viral infections, or as a side effect of medication and treatment. Thus, the risk and safety of these vaccines, in combination with other therapies that could induce myocarditis (e.g., immune checkpoint inhibitor (ICI) therapy), are still poorly assessable. Therefore, vaccine safety, with respect to worsening myocardial inflammation and myocardial function, was studied in an animal model of experimentally induced autoimmune myocarditis. Furthermore, it is known that ICI treatment (e.g., antibodies (abs) against PD-1, PD-L1, and CTLA-4, or a combination of those) plays an important role in the treatment of oncological patients. However, it is also known that treatment with ICIs can induce severe, life-threatening myocarditis in some patients. Genetically different A/J (most susceptible strain) and C57BL/6 (resistant strain) mice, with diverse susceptibilities for induction of experimental autoimmune myocarditis (EAM) at various age and gender, were vaccinated twice with SARS-CoV-2 mRNA-vaccine. In an additional A/J group, an autoimmune myocarditis was induced. In regard to ICIs, we tested the safety of SARS-CoV-2 vaccination in PD-1^-/- mice alone, and in combination with CTLA-4 abs. Our results showed no adverse effects related to inflammation and heart function after mRNA-vaccination, independent of age, gender, and in different mouse strains susceptible for induction of experimental myocarditis. Moreover, there was no worsening effect on inflammation and cardiac function when EAM in susceptible mice was induced. However, in the experiments with vaccination and ICI treatment, we observed, in some mice, low elevation of cardiac troponins in sera, and low scores of myocardial inflammation. In sum, mRNA-vaccines are safe in a model of experimentally induced autoimmune myocarditis, but patients undergoing ICI therapy should be closely monitored when vaccinated.

Coronary artery disease, left ventricular function and cardiac biomarkers determine all-cause mortality in cancer patients-a large monocenter cohort study

Cancer patients are at risk of suffering from cardiovascular diseases (CVD). Nevertheless, the impact of cardiovascular comorbidity on all-cause mortality (ACM) in large clinical cohorts is not well investigated. In this retrospective cohort study, we collected data from 40,329 patients who were subjected to cardiac catherization from 01/2006 to 12/2017 at University Hospital Heidelberg. The study population included 3666 patients with a diagnosis of cancer prior to catherization and 3666 propensity-score matched non-cancer patients according to age, gender, diabetes and hypertension. 5-year ACM in cancer patients was higher with a reduced left ventricular function (LVEF < 50%; 68.0% vs 50.9%) or cardiac biomarker elevation (high-sensitivity cardiac troponin T (hs-cTnT; 64.6% vs 44.6%) and N-terminal brain natriuretic peptide (NT-proBNP; 62.9% vs 41.4%) compared to cancer patients without cardiac risk. Compared to non-cancer patients, NT-proBNP was found to be significantly higher (median NT-proBNP cancer: 881 ng/L, IQR [254; 3983 ng/L] vs non-cancer: 668 ng/L, IQR [179; 2704 ng/L]; p < 0.001, Wilcoxon-rank sum test) and turned out to predict ACM more accurately than hs-cTnT (NT-proBNP: AUC: 0.74; hs-cTnT: AUC: 0.63; p < 0.001, DeLong's test) in cancer patients. Risk factors for atherosclerosis, such as diabetes and age (> 65 years) were significant predictors for increased ACM in cancer patients in a multivariate analysis (OR diabetes: 1.96 (1.39-2.75); p < 0.001; OR age > 65 years: 2.95 (1.68-5.4); p < 0.001, logistic regression). Our data support the notion, that overall outcome in cancer patients who underwent cardiac catherization depends on cardiovascular comorbidities. Therefore, particularly cancer patients may benefit from standardized cardiac care.

Hormonal therapies up-regulate MANF and overcome female susceptibility to immune checkpoint inhibitor myocarditis

Immune checkpoint inhibitors (ICIs) have been increasingly used in combination for cancer treatment but are associated with myocarditis. Here, we report that tumor-bearing mice exhibited response to treatment with combinatorial anti-programmed cell death 1 and anti-cytotoxic T lymphocyte antigen-4 antibodies but also presented with cardiovascular toxicities observed clinically with ICI therapy, including myocarditis and arrhythmia. Female mice were preferentially affected with myocarditis compared to male mice, consistent with a previously described genetic model of ICI myocarditis and emerging clinical data. Mechanistically, myocardial tissue from ICI-treated mice, the genetic mouse model, and human heart tissue from affected patients with ICI myocarditis all exhibited down-regulation of MANF (mesencephalic astrocyte-derived neurotrophic factor) and HSPA5 (heat shock 70-kDa protein 5) in the heart; this down-regulation was particularly notable in female mice. ICI myocarditis was amplified by heart-specific genetic deletion of mouse Manf and was attenuated by administration of recombinant MANF protein, suggesting a causal role. Ironically, both MANF and HSPA5 were transcriptionally induced by liganded estrogen receptor β and inhibited by androgen receptor. However, ICI treatment reduced serum estradiol concentration to a greater extent in female compared to male mice. Treatment with an estrogen receptor β-specific agonist and androgen depletion therapy attenuated ICI-associated cardiac effects. Together, our data suggest that ICI treatment inhibits estradiol-dependent expression of MANF/HSPA5 in the heart, curtailing the cardiomyocyte response to immune injury. This endocrine-cardiac-immune pathway offers new insights into the mechanisms of sex differences in cardiac disease and may offer treatment strategies for ICI myocarditis.

Cancer-A Major Cardiac Comorbidity With Implications on Cardiovascular Metabolism

Cardiovascular diseases have multifactorial causes. Classical cardiovascular risk factors, such as arterial hypertension, smoking, hyperlipidemia, and diabetes associate with the development of vascular stenoses and coronary heart disease. Further comorbidities and its impact on cardiovascular metabolism have gotten more attention recently. Thus, also cancer biology may affect the heart, apart from cardiotoxic side effects of chemotherapies. Cancer is a systemic disease which primarily leads to metabolic alterations within the tumor. An emerging number of preclinical and clinical studies focuses on the interaction between cancer and a maladaptive crosstalk to the heart. Cachexia and sarcopenia can have dramatic consequences for many organ functions, including cardiac wasting and heart failure. These complications significantly increase mortality and morbidity of heart failure and cancer patients. There are concurrent metabolic changes in fatty acid oxidation (FAO) and glucose utilization in heart failure as well as in cancer, involving central molecular regulators, such as PGC-1α. Further, specific inflammatory cytokines (IL-1β, IL-6, TNF-α, INF-β), non-inflammatory cytokines (myostatin, SerpinA3, Ataxin-10) and circulating metabolites (D2-HG) may mediate a direct and maladaptive crosstalk of both diseases. Additionally, cancer therapies, such as anthracyclines and angiogenesis inhibitors target common metabolic mechanisms in cardiomyocytes and malignant cells. This review focuses on cardiovascular, cancerous, and cancer therapy-associated alterations on the systemic and cardiac metabolic state.

High-sensitivity cardiac troponin T determines all-cause mortality in cancer patients: a single-centre cohort study

Aims

Cardio‐oncology is a growing interdisciplinary field which aims to improve cardiological care for cancer patients in order to reduce morbidity and mortality. The impact of cardiac biomarkers, echocardiographic parameters, and cardiological assessment regarding risk stratification is still unclear. We aimed to identify potential parameters that allow an early risk stratification of cancer patients.

Methods and results

In this cohort study, we evaluated 930 patients that were admitted to the cardio‐oncology outpatient clinic of the University Hospital Heidelberg from January 2016 to January 2019. We performed echocardiography, including Global Longitudinal Strain (GLS) analysis and measured cardiac biomarkers including N‐terminal pro brain‐type natriuretic peptide (NT‐proBNP) and high‐sensitivity cardiac troponin T levels (hs‐cTnT). Most patients were suffering from breast cancer (n = 450, 48.4%), upper gastrointestinal carcinoma (n = 99, 10.6%) or multiple myeloma (n = 51, 5.5%). At the initial visit, we observed 86.7% of patients having a preserved left ventricular ejection fraction (LVEF >50%). At the second follow up, still 78.9% of patients showed a preserved LVEF. Echocardiographic parameters or elevation of NT‐proBNP did not significantly correlate with all‐cause mortality (ACM) (logistic regression LVEF <50%: P = 0.46, NT‐proBNP: P = 0.16) and failed to identify high‐risk patients. In contrast, hs‐cTnT above the median (≥7 ng/L) was an independent marker to determine ACM (multivariant logistic regression, OR: 2.21, P = 0.0038) among all included patients. In particular, hs‐cTnT levels before start of a chemotherapy were predictive for ACM.

Conclusions

Based on our non‐selected cohort of cardio‐oncological patients, hs‐cTnT was able to identify patients with high mortality by using a low cutoff of 7 ng/L. We conclude that measurement of hs‐cTnT is an important tool to stratify the risk for mortality of cancer patients before starting chemotherapy.

Clinical Strategy for the Diagnosis and Treatment of Immune Checkpoint Inhibitor-Associated Myocarditis: A Narrative Review

Importance

In the last decade, immune checkpoint inhibitors (ICIs) have been approved for the treatment of many cancer types. Immune checkpoint inhibitor-associated myocarditis has emerged as a significant and potentially fatal adverse effect. Recognizing, diagnosing, and treating ICI-associated myocarditis poses new challenges for the practicing clinician. Here, the current literature on ICI-associated myocarditis is reviewed.

Observations

Clinical presentation and cardiac pathological findings are highly variable in patients with ICI-associated myocarditis. Although endomyocardial biopsy is the criterion standard diagnostic test, a combination of clinical suspicion, cardiac biomarkers (specifically troponin), and cardiac imaging, in addition to biopsy, is often needed to support the diagnosis. Importantly, the combination of a cytotoxic T-lymphocyte-associated protein 4 inhibitor with a programmed cell death protein 1 or programmed death-ligand 1 inhibitor increases the risk of developing ICI-associated myocarditis.

Conclusion and Relevance

This review aims to provide a standardized diagnostic and therapeutic approach for patients with suspected ICI-associated myocarditis. A complete history of recent cancer treatments and physical examination in combination with cardiac biomarkers, cardiac imaging, and endomyocardial biopsy represent a pragmatic diagnostic approach for most cases of ICI-associated myocarditis. The addition of novel biomarkers or imaging modalities is an area of active research and should be evaluated in larger cohorts.

Epigenetic regulation of cardiac electrophysiology in atrial fibrillation: HDAC2 determines action potential duration and suppresses NRSF in cardiomyocytes

Atrial fibrillation (AF) is associated with electrical remodeling, leading to cellular electrophysiological dysfunction and arrhythmia perpetuation. Emerging evidence suggests a key role for epigenetic mechanisms in the regulation of ion channel expression. Histone deacetylases (HDACs) control gene expression through deacetylation of histone proteins. We hypothesized that class I HDACs in complex with neuron-restrictive silencer factor (NRSF) determine atrial K⁺ channel expression. AF was characterized by reduced atrial HDAC2 mRNA levels and upregulation of NRSF in humans and in a pig model, with regional differences between right and left atrium. In vitro studies revealed inverse regulation of Hdac2 and Nrsf in HL-1 atrial myocytes. A direct association of HDAC2 with active regulatory elements of cardiac K⁺ channels was revealed by chromatin immunoprecipitation. Specific knock-down of Hdac2 and Nrsf induced alterations of K⁺ channel expression. Hdac2 knock-down resulted in prolongation of action potential duration (APD) in neonatal rat cardiomyocytes, whereas inactivation of Nrsf induced APD shortening. Potential AF-related triggers were recapitulated by experimental tachypacing and mechanical stretch, respectively, and exerted differential effects on the expression of class I HDACs and K⁺ channels in cardiomyocytes. In conclusion, HDAC2 and NRSF contribute to AF-associated remodeling of APD and K⁺ channel expression in cardiomyocytes via direct interaction with regulatory chromatin regions. Specific modulation of these factors may provide a starting point for the development of more individualized treatment options for atrial fibrillation.

Early Detection of Checkpoint Inhibitor-Associated Myocarditis Using 68Ga-FAPI PET/CT

Objective: Checkpoint inhibitors (ICIs) have gained importance in recent years regarding the treatment of a variety of oncologic diseases. The possibilities of diagnosing cardiac adverse autoimmune effects of ICIs are still limited. We aimed to implement FAPI PET/CT imaging in detecting ICI-associated myocarditis.

Methods: In a retrospective study, FAPI PET/CT scans of 26 patients who received ICIs from 01/2017 to 10/2019 were analyzed. We compared tracer enrichment in the heart of patients without any signs of a cardiac disease (n = 23) to three patients with suspected ICI-associated myocarditis. To exclude any significant coronary heart disease, cardiac catherization was performed. All three patients' myocardial biopsies were examined for inflammatory cells.

Results: Three patients showed clinical manifestations of an ICI syndrome including myocarditis with elevated levels of hsTnT (175 pg/ml, 1,771 pg/ml, 157 pg/ml). Further cardiological assessments revealed ECG abnormalities, lymphocyte infiltration of the myocardium in the biopsies or wall motion abnormalities in echocardiography. These patients' FAPI PET/CTs showed cardiac enrichment of the marker which was less distinct or absent in patients receiving ICIs without any signs of immunological adverse effects or cardiac impairment (n = 23) [Median SUV myocarditis patients: 1.79 (IQR: 1.65, 1.85), median SUV non-myocarditis patients: 1.15 (IQR: 0.955, 1.52)].

Conclusions: Apart from the successful implementation of ICIs in oncological treatments, ICI-associated myocarditis is still a challenging adverse effect. FAPI PET/CT may be used in order to identify affected patients at an early stage. Moreover, when integrated into cancer stage diagnostics, it contributes to cardiac risk stratification besides biomarker, ECG and echocardiography.

Back to the vinyl age: a narrative report of a total computer blackout at a large university medical centre

We report here our experience during a total blackout of all computer systems at a large-scale medical university centre lasting for almost 2 days, affecting not only the hospital information system but also all picture archieving systems, access to laboratory data, office, and email software and even the personnel's ability to log into their accounts. While initially threatening, staff quickly adapted to the situation and the promise of 'digital health' to enable more time for the patient and improve communication, was essentially fulfilled when our computer system was totally down. Based on our experience, we recommend an involvement of health professionals and their medical societies in every step of the digital transformation to accomplish this mission in a responsible, safe, and human-centred way.

[Mechanisms of cardiotoxicity of oncological therapies]

BACKGROUND

Oncological therapies show a number of undesired adverse effects on the cardiovascular system. In particular, the side effects of recently established oncological therapies are incompletely understood and clinical data are lacking in the interpretation of novel cardiac complications.

OBJECTIVE

This article provides a short overview of the mechanisms of cardiac side effects of certain oncological therapies.

MATERIAL AND METHODS

The review is mainly based on data from preclinical studies.

RESULTS

Numerous toxic side effects have already been described and investigated in preclinical models. For certain groups of drugs (e.g. anthracyclines, tyrosine kinase inhibitors and immune checkpoint inhibitors) the underlying molecular mechanisms are still not fully understood.

CONCLUSION

An improved understanding of the molecular mechanism involved in cardiotoxicity might help improve the quality of clinical decisions. Additionally, it will provide new insights into the pathophysiology of cardiac diseases. The aim is to use the results of translational research and to clinically implement them in suitable cardio-oncology units.

Onco-Cardiology: Consensus Paper of the German Cardiac Society, the German Society for Pediatric Cardiology and Congenital Heart Defects and the German Society for Hematology and Medical Oncology

The acute and long-lasting side effects of modern multimodal tumour therapy significantly impair quality of life and survival of patients afflicted with malignancies. The key components of this therapy include radiotherapy, conventional chemotherapy, immunotherapy and targeted therapies. In addition to established tumour therapy strategies, up to 30 new therapies are approved each year with only incompletely characterised side effects. This consensus paper discusses the risk factors that contribute to the development of a potentially adverse reaction to tumour therapy and, in addition, defines specific side effect profiles for different treatment groups. The focus is on novel therapeutics and recommendations for the surveillance and treatment of specific patient groups.

Relationship Between Cardiac Fibroblast Activation Protein Activity by Positron Emission Tomography and Cardiovascular Disease

Supplemental Digital Content is available in the text.

Background:

FAP (fibroblast activation protein) plays an important role in cardiac wound healing and remodeling. Although initially developed as a theranostic ligand for metastasized cancer, FAPI (FAP inhibitor) tracers have recently been used to study cardiac remodeling following myocardial infarction in small-animal models. The aim of the study was to evaluate the activity of FAP via FAPI–positron emission tomography–computed tomography scans in human hearts.

Methods:

FAPI–positron emission tomography–computed tomography scans of 229 patients of 2 consecutive cohorts (modeling cohort: n=185; confirmatory cohort: n=44) suffering from metastasized cancer were analyzed applying the American Heart Association 17-segment model of the left ventricle. Logistic regression models were created using data from the modeling cohort. Multivariate regression models were established using Akaike information criterion in a step-down approach.

Results:

Fourteen percent of patients had preexisting coronary artery disease (n=31), 33% arterial hypertension (n=75), and 12% diabetes mellitus type II (n=28). Forty-three percent had been treated with platin derivatives (n=100), 14% with anthracyclines (n=32), and 10% had a history of prior radiation to the chest (n=23). High left ventricular FAPI signals correlated with the presence of cardiovascular risk factors (odds ratio [OR], 4.3, P=0.0029), a focal myocardial signal pattern (OR, 3.9, P=0.0068), diabetes mellitus type II (OR, 4.1, P=0.046), and beta-blocker use (OR, 3.8, P=0.049) in univariate regression models. In a multivariate analysis, increased signal intensity was significantly higher in patients with cardiovascular risk factors (overweight [OR, 2.6, P=0.023], diabetes mellitus type II [OR, 2.9, P=0.041], certain chemotherapies [platinum derivatives; OR, 3.0, P=0.034], and a history of radiation to the chest [OR, 3.5, P=0.024]). A focal enrichment pattern was more frequently observed in patients with known cardiovascular risk factors (P<0.0001).

Conclusions:

FAPI–positron emission tomography–computed tomography scans represent a new imaging modality to investigate cardiac FAP. High signal intensities correlate with cardiovascular risk factors and metabolic disease.

The lipid droplet-associated protein ABHD5 protects the heart through proteolysis of HDAC4

Catecholamines stimulate the first step of lipolysis by PKA-dependent release of the lipid droplet-associated protein ABHD5 from perilipin to co-activate the lipase ATGL. Here, we unmask a yet unrecognized proteolytic and cardioprotective function of ABHD5. ABHD5 acts in vivo and in vitro as a serine protease cleaving HDAC4. Through the production of an N-terminal polypeptide of HDAC4 (HDAC4-NT), ABHD5 inhibits MEF2-dependent gene expression and thereby controls glucose handling. ABHD5-deficiency leads to neutral lipid storage disease in mice. Cardiac-specific gene therapy of HDAC4-NT does not protect from intra-cardiomyocyte lipid accumulation but strikingly from heart failure, thereby challenging the concept of lipotoxicity-induced heart failure. ABHD5 levels are reduced in failing human hearts and murine transgenic ABHD5 expression protects from pressure-overload induced heart failure. These findings represent a conceptual advance by connecting lipid with glucose metabolism through HDAC4 proteolysis and enable new translational approaches to treat cardiometabolic disease.

[Cardiac arrhythmias in oncological diseases, during radiotherapy, chemotherapy]

Patients with oncological diseases frequently show cardiac arrhythmias. This is explained by an increased risk in this specific patient cohort and is frequently associated with specific oncological therapies. So far, it is unclear how to deal with the occurrence of arrhythmias diagnostically and therapeutically, since the current clinical data do not provide satisfying answers to these questions. Clinical care of high-risk patients in specialized teams with a focus on cardio-oncology is recommended. Based on the current clinical studies and the position papers of the European Society of Cardiology (ESC), we give a brief overview of arrhythmias in malignant diseases and their therapies.

Evidence for a cardiac metabolic switch in patients with Hodgkin's lymphoma

AIMS

Our aim was to investigate the glucose uptake in cancer patients suffering from different entities, using ¹⁸ F-FDG positron emission tomography-computed tomography scans. We further aimed at identifying potential variables altering cardiac and skeletal muscle glucose metabolism.

METHODS AND RESULTS

In a retrospective cohort study, we analysed cardiac and skeletal muscle ¹⁸ F-FDG uptake in onco-positron emission tomography-computed tomography scans in adult patients suffering from Hodgkin's lymphoma, non-Hodgkin's lymphoma, and non-lymphatic cancer including patients suffering from thyroid cancer, bronchial carcinoma, and malignant melanoma. Univariate logistic regression models were created for increased cardiac and skeletal muscle ¹⁸ F-FDG uptake using cancer entity, sex, age, previous radiation, previous chemotherapy, diabetes, obesity, serum glucose levels, renal function, and thyroid function as parameters. Multivariate models were created by selecting variables according to Akaike's information criterion in a step-down approach. Between 2014 and 2018, a total of 337 consecutive patients suffering from Hodgkin's lymphoma (n = 52), non-Hodgkin's lymphoma (n = 57), and non-lymphatic cancer (n = 228) were included in the analysis. Univariate logistic regression models showed high serum glucose levels to be associated with lower absorption rates in both cardiac and skeletal muscle (odds ratio [OR] 0.38 [0.23, 0.60, 95% confidence interval-CI], P < 0.0001, and 0.52 [0.33, 0.82, 95% CI], P < 0.005, respectively). Hodgkin's lymphoma was associated with an increase in cardiac uptake (OR 2.4 [1.3, 4.5, 95% CI], P < 0.005). Decreased skeletal muscle ¹⁸ F-FDG uptake was noted in elderly and obese patients. In our multivariate analysis, Hodgkin's lymphoma patients showed higher cardiac ¹⁸ F-FDG uptake, while non-Hodgkin's lymphoma patients did not differ significantly from non-lymphatic cancer patients (OR 1.6 [0.7, 3.3, 95% CI], P = 0.24). High serum glucose levels and prior chemotherapy were both associated with a significantly decreased cardiac ¹⁸ F-FDG uptake (OR 0.40 [0.24, 0.65, 95% CI], P < 0.0005, and 0.50 [0.27, 0.90, 95% CI], P < 0.05, respectively). Notably, prior chemotherapy did not influence FDG uptake in skeletal muscle to the same extent. Obesity and older age were both significantly associated with decreased gluteal ¹⁸ F-FDG uptake (OR 0.49 [0.27, 0.89, 95% CI], P < 0.05, and 0.47 [0.25, 0.87, 95% CI], P < 0.05).

CONCLUSIONS

Our data provide evidence for metabolic alterations in patients with Hodgkin's lymphoma related to cardiac glucose uptake in humans. This effect was independent from skeletal muscle metabolism.

O-GlcNAcylation of Histone Deacetylase 4 Protects the Diabetic Heart From Failure

BACKGROUND

Worldwide, diabetes mellitus and heart failure represent frequent comorbidities with high socioeconomic impact and steadily growing incidence, calling for a better understanding of how diabetic metabolism promotes cardiac dysfunction. Paradoxically, some glucose-lowering drugs have been shown to worsen heart failure, raising the question of how glucose mediates protective versus detrimental cardiac signaling. Here, we identified a histone deacetylase 4 (HDAC4) subdomain as a molecular checkpoint of adaptive and maladaptive signaling in the diabetic heart.

METHODS

A conditional HDAC4 allele was used to delete HDAC4 specifically in cardiomyocytes (HDAC4-knockout). Mice were subjected to diabetes mellitus either by streptozotocin injections (type 1 diabetes mellitus model) or by crossing into mice carrying a leptin receptor mutation (db/db; type 2 diabetes mellitus model) and monitored for remodeling and cardiac function. Effects of glucose and the posttranslational modification by β-linked N-acetylglucosamine (O-GlcNAc) on HDAC4 were investigated in vivo and in vitro by biochemical and cellular assays.

RESULTS

We show that the cardio-protective N-terminal proteolytic fragment of HDAC4 is enhanced in vivo in patients with diabetes mellitus and mouse models, as well as in vitro under high-glucose and high-O-GlcNAc conditions. HDAC4-knockout mice develop heart failure in models of type 1 and type 2 diabetes mellitus, whereas wild-type mice do not develop clear signs of heart failure, indicating that HDAC4 protects the diabetic heart. Reexpression of the N-terminal fragment of HDAC4 prevents HDAC4-dependent diabetic cardiomyopathy. Mechanistically, the posttranslational modification of HDAC4 at serine (Ser)-642 by O-GlcNAcylation is an essential step for production of the N-terminal fragment of HDAC4, which was attenuated by Ca²⁺/calmodulin-dependent protein kinase II-mediated phosphorylation at Ser-632. Preventing O-GlcNAcylation at Ser-642 not only entirely precluded production of the N-terminal fragment of HDAC4 but also promoted Ca²⁺/calmodulin-dependent protein kinase II-mediated phosphorylation at Ser-632, pointing to a mutual posttranslational modification cross talk of (cardio-detrimental) phosphorylation at Ser-632 and (cardio-protective) O-GlcNAcylation at Ser-642.

CONCLUSIONS

In this study, we found that O-GlcNAcylation of HDAC4 at Ser-642 is cardio-protective in diabetes mellitus and counteracts pathological Ca²⁺/calmodulin-dependent protein kinase II signaling. We introduce a molecular model explaining how diabetic metabolism possesses important cardio-protective features besides its known detrimental effects. A deeper understanding of the here-described posttranslational modification cross talk may lay the groundwork for the development of specific therapeutic concepts to treat heart failure in the context of diabetes mellitus.

CaMKII activation participates in doxorubicin cardiotoxicity and is attenuated by moderate GRP78 overexpression

The clinical use of the chemotherapeutic doxorubicin (Dox) is limited by cardiotoxic side-effects. One of the early Dox effects is induction of a sarcoplasmic reticulum (SR) Ca²⁺ leak. The chaperone Glucose regulated protein 78 (GRP78) is important for Ca²⁺ homeostasis in the endoplasmic reticulum (ER)—the organelle corresponding to the SR in non-cardiomyocytes—and has been shown to convey resistance to Dox in certain tumors. Our aim was to investigate the effect of cardiac GRP78 gene transfer on Ca²⁺ dependent signaling, cell death, cardiac function and survival in clinically relevant in vitro and in vivo models for Dox cardiotoxicity.By using neonatal cardiomyocytes we could demonstrate that Dox induced Ca²⁺ dependent Ca²⁺ /calmodulin-dependent protein kinase II (CaMKII) activation is one of the factors involved in Dox cardiotoxicity by promoting apoptosis. Furthermore, we found that adeno-associated virus (AAV) mediated GRP78 overexpression partly protects neonatal cardiomyocytes from Dox induced cell death by modulating Ca²⁺ dependent pathways like the activation of CaMKII, phospholamban (PLN) and p53 accumulation. Most importantly, cardiac GRP78 gene therapy in mice treated with Dox revealed improved diastolic function (dP/dtmin) and survival after Dox treatment. In conclusion, our results demonstrate for the first time that Ca²⁺ dependent CaMKII activation fosters Dox cardiomyopathy and provide additional insight into possible mechanisms by which GRP78 overexpression protects cardiomyocytes from Doxorubicin toxicity.

Experimental ischaemic stroke induces transient cardiac atrophy and dysfunction

BACKGROUND

Stroke can lead to cardiac dysfunction in patients, but the mechanisms underlying the interaction between the injured brain and the heart are poorly understood. The objective of the study is to investigate the effects of experimental murine stroke on cardiac function and molecular signalling in the heart.

METHODS AND RESULTS

Mice were subjected to filament-induced left middle cerebral artery occlusion for 30 or 60 min or sham surgery and underwent repetitive micro-echocardiography. Left ventricular contractility was reduced early (24-72 h) but not late (2 months) after brain ischaemia. Cardiac dysfunction was accompanied by a release of high-sensitive cardiac troponin (hsTNT (ng/ml): d1: 7.0 ± 1.0 vs. 25.0 ± 3.2*; d3: 7.3 ± 1.1 vs. 52.2 ± 16.7*; d14: 5.7 ± 0.8 vs. 5.2 ± 0.3; sham vs. 60 min. MCAO; mean ± SEM; *p < 0.05); reduced heart weight (heart weight/tibia length ratio: d1: 6.9 ± 0.2 vs. 6.4 ± 0.1*; d3: 6.7 ± 0.2 vs. 5.8 ± 0.1*; d14: 6.7 ± 0.2 vs. 6.4 ± 03; sham vs. 60 min. MCAO; mean ± SEM; *p < 0.05); resulting from cardiomyocyte atrophy (cardiomyocyte size: d1: 12.8% ± 0.002**; d3: 13.5% ± 0.002**; 14d: 6.3% ± 0.003*; 60 min. MCAO vs. sham; mean ± SEM; **p < 0.01; *p < 0.05), accompanied by increased atrogin-1 and the E3 ubiquitin ligase murf-1. Net norepinephrine but not synthesis was increased, suggesting a reduced norepinephrine release or an increase of norepinephrine re-uptake, resulting in a functional denervation. Transcriptome analysis in cardiac tissue identified the transcription factor peroxisome proliferator-activated receptor gamma as a potential mediator of stroke-induced transcriptional dysregulation involved in cardiac atrophy.

CONCLUSIONS

Stroke induces a complex molecular response in the heart muscle with immediate but transient cardiac atrophy and dysfunction.

Cardiovascular adverse events in multiple myeloma patients

Multiple myeloma is a malignant disease, caused by an uncontrolled clonal proliferation of a specific group of white blood cells, the plasma cells. Clinical manifestations include bone pain due to osteolysis, hypercalcemia, anemia, and renal insufficiency. Proteasome inhibitors have substantially improved survival of patients suffering from multiple myeloma, providing an efficient treatment option mainly for relapsed and refractory multiple myeloma. Although constituting one substance class, bortezomib, carfilzomib, and ixazomib differ greatly regarding their non-hematologic side effects. This article reviews the clinical and preclinical data on approved proteasome inhibitors in an attempt to decipher the underlying pathomechanisms related to cardiovascular adverse events seen in clinical trials.

Cardio-oncology: conflicting priorities of anticancer treatment and cardiovascular outcome

BACKGROUND

This article about the emerging field of cardio-oncology highlights typical side effects of oncological therapies in the cardiovascular system, cardiovascular complications of malignancies itself, and potential preventive or therapeutic modalities.

METHODS

We performed a selective literature search in PubMed until September 2016.

RESULTS

Cardiovascular events in cancer patients can be frequently attributed to oncological therapies or to the underlying malignancy itself. Furthermore, many patients with cancer have pre-existing cardiovascular diseases that can be aggravated by the malignancy or its therapy. Cardiovascular abnormalities in oncological patients comprise a broad spectrum from alterations in electrophysiological, laboratory or imaging tests to the occurrence of thromboembolic, ischemic or rhythmological events and the impairment of left ventricular function or manifest heart failure.

DISCUSSION

A close interdisciplinary collaboration between oncologists and cardiologists/angiologists as well as an increased awareness of potential cardiovascular complications could improve clinical care of cancer patients and provides a basis for an improved understanding of underlying mechanisms of cardiovascular morbidity.

Inhibition of Endothelial Notch Signaling Impairs Fatty Acid Transport and Leads to Metabolic and Vascular Remodeling of the Adult Heart

BACKGROUND

Nutrients are transported through endothelial cells before being metabolized in muscle cells. However, little is known about the regulation of endothelial transport processes. Notch signaling is a critical regulator of metabolism and angiogenesis during development. Here, we studied how genetic and pharmacological manipulation of endothelial Notch signaling in adult mice affects endothelial fatty acid transport, cardiac angiogenesis, and heart function.

METHODS

Endothelial-specific Notch inhibition was achieved by conditional genetic inactivation of Rbp-jκ in adult mice to analyze fatty acid metabolism and heart function. Wild-type mice were treated with neutralizing antibodies against the Notch ligand Delta-like 4. Fatty acid transport was studied in cultured endothelial cells and transgenic mice.

RESULTS

Treatment of wild-type mice with Delta-like 4 neutralizing antibodies for 8 weeks impaired fractional shortening and ejection fraction in the majority of mice. Inhibition of Notch signaling specifically in the endothelium of adult mice by genetic ablation of Rbp-jκ caused heart hypertrophy and failure. Impaired heart function was preceded by alterations in fatty acid metabolism and an increase in cardiac blood vessel density. Endothelial Notch signaling controlled the expression of endothelial lipase, Angptl4, CD36, and Fabp4, which are all needed for fatty acid transport across the vessel wall. In endothelial-specific Rbp-jκ-mutant mice, lipase activity and transendothelial transport of long-chain fatty acids to muscle cells were impaired. In turn, lipids accumulated in the plasma and liver. The attenuated supply of cardiomyocytes with long-chain fatty acids was accompanied by higher glucose uptake, increased concentration of glycolysis intermediates, and mTOR-S6K signaling. Treatment with the mTOR inhibitor rapamycin or displacing glucose as cardiac substrate by feeding a ketogenic diet prolonged the survival of endothelial-specific Rbp-jκ-deficient mice.

CONCLUSIONS

This study identifies Notch signaling as a novel regulator of fatty acid transport across the endothelium and as an essential repressor of angiogenesis in the adult heart. The data imply that the endothelium controls cardiomyocyte metabolism and function.

Nucleoside Diphosphate Kinase-C Suppresses cAMP Formation in Human Heart Failure

BACKGROUND

Chronic heart failure (HF) is associated with altered signal transduction via β-adrenoceptors and G proteins and with reduced cAMP formation. Nucleoside diphosphate kinases (NDPKs) are enriched at the plasma membrane of patients with end-stage HF, but the functional consequences of this are largely unknown, particularly for NDPK-C. Here, we investigated the potential role of NDPK-C in cardiac cAMP formation and contractility.

METHODS

Real-time polymerase chain reaction, (far) Western blot, immunoprecipitation, and immunocytochemistry were used to study the expression, interaction with G proteins, and localization of NDPKs. cAMP levels were determined with immunoassays or fluorescent resonance energy transfer, and contractility was determined in cardiomyocytes (cell shortening) and in vivo (fractional shortening).

RESULTS

NDPK-C was essential for the formation of an NDPK-B/G protein complex. Protein and mRNA levels of NDPK-C were upregulated in end-stage human HF, in rats after long-term isoprenaline stimulation through osmotic minipumps, and after incubation of rat neonatal cardiomyocytes with isoprenaline. Isoprenaline also promoted translocation of NDPK-C to the plasma membrane. Overexpression of NDPK-C in cardiomyocytes increased cAMP levels and sensitized cardiomyocytes to isoprenaline-induced augmentation of contractility, whereas NDPK-C knockdown decreased cAMP levels. In vivo, depletion of NDPK-C in zebrafish embryos caused cardiac edema and ventricular dysfunction. NDPK-B knockout mice had unaltered NDPK-C expression but showed contractile dysfunction and exacerbated cardiac remodeling during long-term isoprenaline stimulation. In human end-stage HF, the complex formation between NDPK-C and Gα_i2 was increased whereas the NDPK-C/Gα_s interaction was decreased, producing a switch that may contribute to an NDPK-C-dependent cAMP reduction in HF.

CONCLUSIONS

Our findings identify NDPK-C as an essential requirement for both the interaction between NDPK isoforms and between NDPK isoforms and G proteins. NDPK-C is a novel critical regulator of β-adrenoceptor/cAMP signaling and cardiac contractility. By switching from Gα_s to Gα_i2 activation, NDPK-C may contribute to lower cAMP levels and the related contractile dysfunction in HF.

Inducible cardiomyocyte-specific deletion of CaM kinase II protects from pressure overload-induced heart failure

CaM kinase II (CaMKII) has been suggested to drive pathological cardiac remodeling and heart failure. However, the evidence provided so far is based on inhibitory strategies using chemical compounds and peptides that also exert off-target effects and followed exclusively preventive strategies. Therefore, the aim of this study was to investigate whether specific CaMKII inhibition after the onset of cardiac stress delays or reverses maladaptive cardiac remodeling and dysfunction. Combined genetic deletion of the two redundant CaMKII genes δ and γ was induced after the onset of overt heart failure as the result of pathological pressure overload induced by transverse aortic constriction (TAC). We used two different strategies to engineer an inducible cardiomyocyte-specific CaMKIIδ/CaMKIIγ double knockout mouse model (DKO): one model bases on tamoxifen-inducible mER/Cre/mER expression under control of the cardiac-specific αMHC promoter; the other strategy bases on overexpression of Cre recombinase via cardiac-specific gene transfer through adeno-associated virus (AAV9) under control of the cardiac-specific myosin light chain promoter. Both models led to a substantial deletion of CaMKII in failing hearts. To approximate the clinical situation, CaMKII deletion was induced 3 weeks after TAC surgery. In both models of DKO, the progression of cardiac dysfunction and interstitial fibrosis could be slowed down as compared to control animals. Taken together, we show for the first time that "therapeutic" CaMKII deletion after cardiac damage is sufficient to attenuate maladaptive cardiac remodeling and to reverse signs of heart failure. These data suggest that CaMKII inhibition is a promising therapeutic approach to combat heart failure.

Abstract 433: Disrupting the Interaction Between CaM Kinase II and Histone Deacetylase 4 - an Epigenetic Therapy for Heart Failure?

CaM Kinase II (CaMKII) critically drives adverse cardiac remodeling. During the process of remodeling, CaMKII binds and phosphorylates Histone Deacetylase 4 (HDAC4), resulting in activation of the transcription factor MEF2. However, it remained unclear whether binding between CaMKII and HDAC4 causes heart failure and whether this interaction represents a novel therapeutic target. We used mouse genetics, HDAC4-based peptides and chemical biology to address these questions. First, we generated CaMKII-resistant HDAC4 mutant mice (CrH) by replacing Arg-598 (corresponds to Arg-601 in humans) of HDAC4 with Phe, because we found Arg-598 to be essential for the CaMKII-HDAC4 interaction. CrH were protected from cardiac dysfunction, hypertrophy and fibrosis in response to both pathological pressure overload or ischemia/reperfusion injury. CrH showed reduced CaMKII binding and less MEF2 activation. These data provided a proof-of-principle that the disruption of the CaMKII-HDAC4 interaction may have therapeutic potential. Thus, in a second step we engineered an HDAC4-derived peptide with homology to the CaMKII binding domain of HDAC4. This peptide competed with HDAC4 for binding with CaMKII, resulting in decreased MEF2 activation and attenuated agonist-induced cardiomyocyte hypertrophy. These data encouraged us to carry the translational pipeline one step further and we screened for small molecules that disrupt the CaMKII-HDAC4 interaction in an in vitro ALPHAScreen Assay (medium-throughput format using 78000 compounds). After a stringent validation process, 38 compounds showed > 40% inhibition. Out of these, 13 compounds effectively inhibited MEF2 activity in a cell-based assay without obvious signs for cellular toxicity, providing now potential cell permeable drug-like candidates. Chemical optimization and in vivo validation strategies are currently ongoing. In summary, we show that the CaMKII-HDAC4 interaction contributes to the development of heart failure and we identified drug-like molecules that specifically disrupt this protein-protein interaction. These findings lay the ground for a novel epigenetic therapeutic approach to combat heart failure.

CaM Kinase II mediates maladaptive post-infarct remodeling and pro-inflammatory chemoattractant signaling but not acute myocardial ischemia/reperfusion injury

CaMKII was suggested to mediate ischemic myocardial injury and adverse cardiac remodeling. Here, we investigated the roles of different CaMKII isoforms and splice variants in ischemia/reperfusion (I/R) injury by the use of new genetic CaMKII mouse models. Although CaMKIIδC was upregulated 1 day after I/R injury, cardiac damage 1 day after I/R was neither affected in CaMKIIδ-deficient mice, CaMKIIδ-deficient mice in which the splice variants CaMKIIδB and C were re-expressed, nor in cardiomyocyte-specific CaMKIIδ/γ double knockout mice (DKO). In contrast, 5 weeks after I/R, DKO mice were protected against extensive scar formation and cardiac dysfunction, which was associated with reduced leukocyte infiltration and attenuated expression of members of the chemokine (C-C motif) ligand family, in particular CCL3 (macrophage inflammatory protein-1α, MIP-1α). Intriguingly, CaMKII was sufficient and required to induce CCL3 expression in isolated cardiomyocytes, indicating a cardiomyocyte autonomous effect. We propose that CaMKII-dependent chemoattractant signaling explains the effects on post-I/R remodeling. Taken together, we demonstrate that CaMKII is not critically involved in acute I/R-induced damage but in the process of post-infarct remodeling and inflammatory processes.

Advanced echocardiography in adult zebrafish reveals delayed recovery of heart function after myocardial cryoinjury

Translucent zebrafish larvae represent an established model to analyze genetics of cardiac development and human cardiac disease. More recently adult zebrafish are utilized to evaluate mechanisms of cardiac regeneration and by benefiting from recent genome editing technologies, including TALEN and CRISPR, adult zebrafish are emerging as a valuable in vivo model to evaluate novel disease genes and specifically validate disease causing mutations and their underlying pathomechanisms. However, methods to sensitively and non-invasively assess cardiac morphology and performance in adult zebrafish are still limited. We here present a standardized examination protocol to broadly assess cardiac performance in adult zebrafish by advancing conventional echocardiography with modern speckle-tracking analyses. This allows accurate detection of changes in cardiac performance and further enables highly sensitive assessment of regional myocardial motion and deformation in high spatio-temporal resolution. Combining conventional echocardiography measurements with radial and longitudinal velocity, displacement, strain, strain rate and myocardial wall delay rates after myocardial cryoinjury permitted to non-invasively determine injury dimensions and to longitudinally follow functional recovery during cardiac regeneration. We show that functional recovery of cryoinjured hearts occurs in three distinct phases. Importantly, the regeneration process after cryoinjury extends far beyond the proposed 45 days described for ventricular resection with reconstitution of myocardial performance up to 180 days post-injury (dpi). The imaging modalities evaluated here allow sensitive cardiac phenotyping and contribute to further establish adult zebrafish as valuable cardiac disease model beyond the larval developmental stage.

Aldosterone augments Na+-induced reduction of cardiac norepinephrine reuptake

Impairment of the cardiac norepinephrine (NE) reuptake by the neuronal NE transporter contributes to enhanced cardiac NE net release in congestive heart failure. Elevated plasma levels of aldosterone (AL) promote sympathetic overstimulation in failing hearts by unclear mechanisms. Our aim was to evaluate if elevated AL and/or alterations in Na(+) intake regulate cardiac NE reuptake. To test the effects of AL and Na(+) on cardiac NE reuptake, Wistar rats were fed a normal-salt (NS) diet (0.2% NaCl), a low-salt (LS) diet (0.015% NaCl), or a high-salt (HS) diet (8% NaCl). Another group of animals received AL infusion alone (0.75 μg/h) or AL infusion plus HS diet. Specific cardiac [(3)H]NE uptake via the NE transporter in a Langendorff preparation and AL plasma levels were measured at different time points between 5 and 42 days of treatment. To compare these findings from healthy animals with a disease model, Dahl salt-sensitive rats were investigated as a model of congestive heart failure with endogenously elevated AL. In summary, neither exogenous nor endogenous elevations of AL alone were sufficient to reduce cardiac NE reuptake. Only the HS diet induced a reduction of NE reuptake by 26%; additional infusion of AL augmented this effect to a further reduction of NE reuptake by 36%. In concordance, Dahl salt-sensitive rats treated with a HS diet displayed elevated AL and a marked reduction of NE reuptake. We conclude that exogenous or endogenous AL elevations alone do not reduce cardiac NE reuptake, but AL serves as an additional factor that negatively regulates cardiac NE reuptake in concert with HS intake.

Cardiac CaM Kinase II genes δ and γ contribute to adverse remodeling but redundantly inhibit calcineurin-induced myocardial hypertrophy

BACKGROUND

Ca(2+)-dependent signaling through CaM Kinase II (CaMKII) and calcineurin was suggested to contribute to adverse cardiac remodeling. However, the relative importance of CaMKII versus calcineurin for adverse cardiac remodeling remained unclear.

METHODS AND RESULTS

We generated double-knockout mice (DKO) lacking the 2 cardiac CaMKII genes δ and γ specifically in cardiomyocytes. We show that both CaMKII isoforms contribute redundantly to phosphorylation not only of phospholamban, ryanodine receptor 2, and histone deacetylase 4, but also calcineurin. Under baseline conditions, DKO mice are viable and display neither abnormal Ca(2+) handling nor functional and structural changes. On pathological pressure overload and β-adrenergic stimulation, DKO mice are protected against cardiac dysfunction and interstitial fibrosis. But surprisingly and paradoxically, DKO mice develop cardiac hypertrophy driven by excessive activation of endogenous calcineurin, which is associated with a lack of phosphorylation at the auto-inhibitory calcineurin A site Ser411. Likewise, calcineurin inhibition prevents cardiac hypertrophy in DKO. On exercise performance, DKO mice show an exaggeration of cardiac hypertrophy with increased expression of the calcineurin target gene RCAN1-4 but no signs of adverse cardiac remodeling.

CONCLUSIONS

We established a mouse model in which CaMKII's activity is specifically and completely abolished. By the use of this model we show that CaMKII induces maladaptive cardiac remodeling while it inhibits calcineurin-dependent hypertrophy. These data suggest inhibition of CaMKII but not calcineurin as a promising approach to attenuate the progression of heart failure.

The role of endothelin-1 in the sympathetic nervous system in the heart

Endothelin-1 (ET1) is a peptide that was initially identified as a strong inductor of vascular contraction. In the last 25 years, there have been several biological processes identified in which ET1 seems to play a critical role. In particular, genetic studies have unveiled that ET1 is important for neuronal development, growth and function. Experimental studies identified ET1 as a regulator of the interaction between sympathetic neurons and cardiac myocytes. This might be of clinical importance since patients suffering from heart failure are characterized by disrupted norepinephrine homeostasis in the heart. This review summarizes the important findings on the role of ET1 for sympathetic neurons and norepinephrine homeostasis in the heart.

Histone deacetylase signaling in cardioprotection

Cardiovascular disease (CVD) represents a major challenge for health care systems, both in terms of the high mortality associated with it and the huge economic burden of its treatment. Although CVD represents a diverse range of disorders, they share common compensatory changes in the heart at the structural, cellular, and molecular level that, in the long term, can become maladaptive and lead to heart failure. Treatment of adverse cardiac remodeling is therefore an important step in preventing this fatal progression. Although previous efforts have been primarily focused on inhibition of deleterious signaling cascades, the stimulation of endogenous cardioprotective mechanisms offers a potent therapeutic tool. In this review, we discuss class I and class II histone deacetylases, a subset of chromatin-modifying enzymes known to have critical roles in the regulation of cardiac remodeling. In particular, we discuss their molecular modes of action and go on to consider how their inhibition or the stimulation of their intrinsic cardioprotective properties may provide a potential therapeutic route for the clinical treatment of CVD.

HDAC4 controls histone methylation in response to elevated cardiac load

In patients with heart failure, reactivation of a fetal gene program, including atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP), is a hallmark for maladaptive remodeling of the LV. The mechanisms that regulate this reactivation are incompletely understood. Histone acetylation and methylation affect the conformation of chromatin, which in turn governs the accessibility of DNA for transcription factors. Using human LV myocardium, we found that, despite nuclear export of histone deacetylase 4 (HDAC4), upregulation of ANP and BNP in failing hearts did not require increased histone acetylation in the promoter regions of these genes. In contrast, di- and trimethylation of lysine 9 of histone 3 (H3K9) and binding of heterochromatin protein 1 (HP1) in the promoter regions of these genes were substantially reduced. In isolated working murine hearts, an acute increase of cardiac preload induced HDAC4 nuclear export, H3K9 demethylation, HP1 dissociation from the promoter region, and activation of the ANP gene. These processes were reversed in hearts with myocyte-specific deletion of Hdac4. We conclude that HDAC4 plays a central role for rapid modifications of histone methylation in response to variations in cardiac load and may represent a target for pharmacological interventions to prevent maladaptive remodeling in patients with heart failure.

Selective repression of MEF2 activity by PKA-dependent proteolysis of HDAC4

Histone deacetylase 4 (HDAC4) regulates numerous gene expression programs through its signal-dependent repression of myocyte enhancer factor 2 (MEF2) and serum response factor (SRF) transcription factors. In cardiomyocytes, calcium/calmodulin-dependent protein kinase II (CaMKII) signaling promotes hypertrophy and pathological remodeling, at least in part by phosphorylating HDAC4, with consequent stimulation of MEF2 activity. In this paper, we describe a novel mechanism whereby protein kinase A (PKA) overcomes CaMKII-mediated activation of MEF2 by regulated proteolysis of HDAC4. PKA induces the generation of an N-terminal HDAC4 cleavage product (HDAC4-NT). HDAC4-NT selectively inhibits activity of MEF2 but not SRF, thereby antagonizing the prohypertrophic actions of CaMKII signaling without affecting cardiomyocyte survival. Thus, HDAC4 functions as a molecular nexus for the antagonistic actions of the CaMKII and PKA pathways. These findings have implications for understanding the molecular basis of cardioprotection and other cellular processes in which CaMKII and PKA exert opposing effects.

Abstract P183: Cardiac Deletion of CaMKII Delta and Gamma Protects Against Heart Failure Despite Activation of Calcineurin Signaling

CaMKII delta and gamma are the major CaMKII genes expressed in the heart, and both are up-regulated in response to pressure overload. Recently, we have demonstrated that CaMKII delta single knockout mice are protected against cardiac hypertrophy and remodeling. However, the role of CaMKII gamma and potential redundant functions of CaMKII delta and gamma are still elusive. The aim of the present study was to evaluate the function of CaMKII delta and gamma by a cardiomyocyte-specific double knockout mouse model(delta/gamma-CKO). Strikingly, whereas delta and gamma single knockout mice displayed only slightly reduced levels of cardiac phospholamban (PLN) phosphorylation at the CaMKII phosphorylation site threonin 17, in delta/gamma-CKO mice there was almost no residual PLN-threonin-17 phosphorylation detectable. Surprisingly and in contrast to delta and gamma single knockout mice, delta/gamma-CKO mice did develop cardiac hypertrophy after transverse aortic constriction (TAC). Despite cardiac hypertrophy we observed markedly reduced cardiac fibrosis and apoptosis. Microarray analysis revealed a distinct different gene expression profile pointing to an activation of calcineurin in delta/gamma-CKO mice after TAC. Phosphorylation of calcineurin at serine 197, which leads to an inactivation of its enzymatic activity, was almost abolished in delta/gamma-CKO mice. To test the therapeutical implications of a complete myocardial CaMKII knockout, an tamoxifen-inducible knockout system was established. Knockout of CaMKII delta and gamma was induced by administration of tamoxifen three weeks after TAC surgery. Whereas control mice did develop overt heart failure and cardiac remodeling 16 weeks after TAC, delta/gamma-iCKO mice recovered from cardiac dysfunction. Taken together, our mouse genetic studies demonstrate that CaMKII delta and gamma are promising drug targets to restore cardiac function after pathological stress. These data also unmask a cross talk of CaMKII to endogenous calcineurin signaling, which results in adaptive cardiac hypertrophy and not pathological remodeling.

Abstract P302: CaMKII Is Not Critical for Ischemia/Reperfusion Injury

Objectives: The role of the Calcium/calmodulin-dependent protein kinase II (CaMKII) in Ischemia/Reperfusion of the heart (I/R) has not completely been clarified yet - partly due to lacking evidence from animal studies with specific gene knockout (KO) strategies. Moreover, the contribution of the nuclear and cytosolic CaMKIIδ splice variants δB and δC to I/R-induced myocardial damage have been controversially discussed. To investigate the role of CaMKII in myocardial I/R we used several KO mice with genetic deletion of the two major isoforms expressed in the heart, CaMKIIδ and CaMKIIγ, respectively. Both single and double KO models were examined. In addition, we developed a reliable approach to express CaMKII δB and δC splice variants in CaMKIIδ-null mice using adeno-associated-virus serotype 9 (AAV9) to investigate their specific roles in I/R.

Methods and Results: A surgical in vivo I/R model was used following two protocols: 30 minutes ischemia with 48 hours of subsequent reperfusion (30/48) and 60 minutes ischemia followed by a 24 hour reperfusion period (60/24). Planimetric measurements of infarct size after staining with Evans Blue and Triphenyl tetrazolium chloride showed no significant difference between CaMKII KO and control groups (infarct-zone/area-at-risk ratio for 30/48-protocol: CaMKIIγ −/− vs. C57/Bl6: 0.49 ± 0.04 vs. 0.43 ± 0.05, p=0.43, n≥6; CaMKIIδ −/− vs. C57/Bl6: 0.42 ± 0.04 vs. 0.44 ± 0.04, p=0.69, n≥19; infarct-zone/area-atrisk ratio for 60/24-protocol: CaMKIIδ −/− vs. C57/Bl6: 0.52 ± 0.02 vs. 0.56 ± 0.03, p=0.33, n≥8; CaMKIIγ loxP/loxP δ loxP/loxP ; alphaMHC-Cre vs. CaMKIIγ loxP/loxP δ loxP/loxP : 0.52 ± 0.03 vs. 0.52 ± 0.04, p=0.86, n≥9). Consistently, no differences in high-sensitive serum troponin T levels 24 hours after onset of ischemia could be detected. Neither histologic TUNEL-staining nor Caspase3/7-acivity assays revealed any significant differences in apoptotic cell death processes. Importantly, specific expression of CaMKII δB or δC splice variants via AAV9 gene transfer - at approximate endogenous protein levels - in CaMKIIδ −/− mice had no effect on infarct size and necrotic or apoptotic markers.

Conclusion: Our findings indicate that CaMKII is not critical for myocardial infarct size and apoptosis in response to I/R.

Acylation of proteins by myristic acid in isolated mitochondria

Isolated and highly purified mitochondria from rat liver were incubated with [1-14C]myristate, solubilized in boiling sodium dodecyl sulfate, and analyzed by polyacrylamide gel electrophoresis and autoradiography. Six to eight protein bands were found to be radioactively labeled. If the mitochondria were heated for 5 min at 95 degrees C prior to incubation with this fatty acid, no labeling was observed. By preexposing the mitochondria to unlabeled fatty acids of varying chain lengths, the extent of labeling by [1-14C]myristate was reduced in a chain length-dependent manner, exhibiting maximal inhibition at lauric acid. Reversibility of the labeling was demonstrated by chasing the incorporated radioactivity with unlabeled fatty acids of varying chain length, resulting in a maximal displacement of the tracer again by lauric acid. Fractionation of the labeled mitochondria into mitochondrial matrix and inner mitochondrial membrane components before or after labeling showed that the modified proteins are located inside the inner mitochondrial membrane. In both cases, the pattern of labeling was different from the one observed with intact mitochondria. The labeled bands in the gel were sensitive to alkaline methanol or hydroxylamine treatment. The radioactivity recovered after this treatment co-migrated with myristic acid on thin layer chromatography plates. The chain length specificity and the rapid reversibility of the observed acylation argue for a new type of reaction, different from the acylation observed in whole cells. The possible involvement of the acylated proteins in the regulation of oxidative phosphorylation is discussed.

Transient kinetics of thermodynamic buffering

The transient response of mitochondrial ATP production towards perturbations was studied by analyzing the trajectories leading from arbitrary initial conditions of the adenine nucleotide pool to the final steady state. These trajectories were calculated from differential equations based on linear relations between flows and thermodynamic forces of the adenylate kinase system including oxidative phosphorylation. The motion of the system along the trajectories consists of two phases: (1) a rapid phase leading from initial states to a common relaxation curve; and (2) a slow phase leading along the relaxation curve to the final steady state. The first phase corresponds to a motion close to the loci of constant adenylic energy charge. In line with this observation is the finding that the energy charge is a constant of motion of the adenylate kinase reaction. The second phase corresponds to a motion along a relaxation curve characterized by minimal Lyapunov exponents in the concentration space of the adenine nucleotides. Thus, both phases of the transient kinetics can be approximated in terms of thermodynamic functions to a high degree of precision. Incubations with isolated rat liver mitochondria were in excellent agreement with the theoretical predictions. In summary, these studies show that the adenylate kinase system not only optimizes the efficiency of oxidative phosphorylation through thermodynamic buffering but, in addition, also deeply influences the transient response of the whole system.