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.

Increased expression of human endogenous retrovirus K in endomyocardial biopsies from patients with cardiomyopathy - a transcriptomics meta-analysis.

Most studied, investigating transcriptional changes in myocardial biopsies focus on human genes. However, the presence and potential consequence of persistent expression of viral genes within the myocardium is unclear. The aim of the study was to analyze viral gene expression in RNAseq data from endomyocardial biopsies. The NCBI Bioproject library was screened for published projects that included bulk RNA sequencing data from endomyocardial biopsies from both healthy and diseased patients with a sample size greater than 20. Diseased patients with hypertrophic, dilated, and ischemic cardiomyopathies were included. A total of 507 patients with 507 samples from 6 bioprojects were included and mapped to the human genome (hg38). Unmappable sequences were extracted and mapped to an artificial 'super-virus' genome comprising 12,182 curated viral reference genomes. Subsequently, the sequences were reiteratively permutated and mapped again to account for randomness. In total, sequences from 68 distinct viruses were found, all of which were potentially human pathogenic. No increase in cardiotropic viruses was found in patients with dilated cardiomyopathy. However, the expression levels of the particle forming human endogenous retrovirus K were significantly increased (q < 0.0003, ANOVA). Higher expression levels were associated with increased expression in mitochondrial pathways such as oxidative phosphorylation (p < 0.0001). In Conclusion, expression of human endogenous retrovirus K is significantly increased in patients with dilated cardiomyopathy, which in turn was associated with transcriptional alterations in major cellular pathways.

Troponin Elevation in Asymptomatic Cancer Patients: Unveiling Connections and Clinical Implications.

PURPOSE OF THE REVIEW: Elevated troponin levels are well established e.g., for the diagnosis of suspected acute coronary syndrome in symptomatic patients. In contrast, troponin elevations in asymptomatic cancer patients emerge as a complex phenomenon, challenging traditional perceptions of its association solely with cardiac events. RECENT FINDINGS: Recent data support the predictive value of cardiac biomarker for all-cause mortality and cardiotoxicity in cancer patients. This review gives an overview about the current literature about cardiac troponins in prediction and identification of high-risk cancer patients. The overview is focusing on diagnostic challenges, biomarker significance, and gaps of knowledge. Latest publications highlight the relevance of cardiac troponin in risk analysis before cancer treatment as well as a potential diagnostic gatekeeper for further cardiological diagnostics and therapy.

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.

Cardio-oncology imaging tools at the translational interface.

Cardiovascular imaging is an evolving component in the care of cancer patients. With improved survival following prompt cancer treatment, patients are facing increased risks of cardiovascular complications. While currently established imaging modalities are providing useful structural mechanical information, they continue to develop towards increased specificity. New modalities, emerging from basic science and oncology, are being translated, targeting earlier stages of cardiovascular disease. Besides these technical advances, matching an imaging modality with the patients' individual risk level for a specific pathological change is part of a successful imaging strategy. The choice of suitable imaging modalities and time points for specific patients will impact the cardio-oncological risk stratification during surveillance and follow-up monitoring. In addition, future imaging tools are poised to give us important insights into the underlying cardiovascular molecular pathology associated with cancer and oncological therapies. This review aims at giving an overview of the novel imaging technologies that have the potential to change cardio-oncological science and clinical practice in the near future.

Histone deacetylase 4 deletion broadly affects cardiac epigenetic repression and regulates transcriptional susceptibility via H3K9 methylation.

Histone deacetylase 4 (HDAC4) is a member of class IIa histone deacetylases (class IIa HDACs) and is believed to possess a low intrinsic deacetylase activity. However, HDAC4 sufficiently represses distinct transcription factors (TFs) such as the myocyte enhancer factor 2 (MEF2). Transcriptional repression by HDAC4 has been suggested to be mediated by the recruitment of other chromatin-modifying enzymes, such as methyltransferases or class I histone deacetylases. However, this concept has not been investigated by an unbiased approach. Therefore, we studied the histone modifications H3K4me3, H3K9ac, H3K27ac, H3K9me2 and H3K27me3 in a genome-wide approach using HDAC4-deficient cardiomyocytes. We identified a general epigenetic shift from a 'repressive' to an 'active' status, characterized by an increase of H3K4me3, H3K9ac and H3K27ac and a decrease of H3K9me2 and H3K27me3. In HDAC4-deficient cardiomyocytes, MEF2 binding sites were considerably overrepresented in upregulated promoter regions of H3K9ac and H3K4me3. For example, we identified the promoter of Adprhl1 as a new genomic target of HDAC4 and MEF2. Overexpression of HDAC4 in cardiomyocytes was able to repress the transcription of the Adprhl1 promoter in the presence of the methyltransferase SUV39H1. On a genome-wide level, the decrease of H3K9 methylation did not change baseline expression but was associated with exercise-induced gene expression. We conclude that HDAC4, on the one hand, associates with activating histone modifications, such as H3K4me3 and H3K9ac. A functional consequence, on the other hand, requires an indirect regulation of H3K9me2. H3K9 hypomethylation in HDAC4 target genes ('first hit') plus a 'second hit' (e.g., exercise) determines the transcriptional response.

CaM kinase II regulates cardiac hemoglobin expression through histone phosphorylation upon sympathetic activation.

Sympathetic activation of ß-adrenoreceptors (ß-AR) represents a hallmark in the development of heart failure (HF). However, little is known about the underlying mechanisms of gene regulation. In human ventricular myocardium from patients with end-stage HF, we found high levels of phosphorylated histone 3 at serine-28 (H3S28p). H3S28p was increased by inhibition of the catecholamine-sensitive protein phosphatase 1 and decreased by ß-blocker pretreatment. By a series of in vitro and in vivo experiments, we show that the ß-AR downstream protein kinase CaM kinase II (CaMKII) directly binds and phosphorylates H3S28. Whereas, in CaMKII-deficient myocytes, acute catecholaminergic stimulation resulted in some degree of H3S28p, sustained catecholaminergic stimulation almost entirely failed to induce H3S28p. Genome-wide analysis of CaMKII-mediated H3S28p in response to chronic ß-AR stress by chromatin immunoprecipitation followed by massive genomic sequencing led to the identification of CaMKII-dependent H3S28p target genes. Forty percent of differentially H3S28p-enriched genomic regions were associated with differential, mostly increased expression of the nearest genes, pointing to CaMKII-dependent H3S28p as an activating histone mark. Remarkably, the adult hemoglobin genes showed an H3S28p enrichment close to their transcriptional start or end sites, which was associated with increased messenger RNA and protein expression. In summary, we demonstrate that chronic ß-AR activation leads to CaMKII-mediated H3S28p in cardiomyocytes. Thus, H3S28p-dependent changes may play an unexpected role for cardiac hemoglobin regulation in the context of sympathetic activation. These data also imply that CaMKII may be a yet unrecognized stress-responsive regulator of hematopoesis.

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.

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 ß-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.

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 ß-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 Gαi2 was increased whereas the NDPK-C/Gαs 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 ß-adrenoceptor/cAMP signaling and cardiac contractility. By switching from Gαs to Gαi2 activation, NDPK-C may contribute to lower cAMP levels and the related contractile dysfunction in HF.

Essential role of sympathetic endothelin A receptors for adverse cardiac remodeling.

In preclinical studies, endothelin receptor A (ETA) antagonists (ETAi) attenuated the progression of heart failure (HF). However, clinical HF trials failed to demonstrate beneficial effects of ETAi. These conflicting data may be explained by the possibility that established HF drugs such as adrenergic receptor blockers interfered with the mechanism of ETAi action in clinical trials. Here we report that mice lacking ETA only in sympathetic neurons (SN-KO) showed less adverse structural remodeling and cardiac dysfunction in response to pathological pressure overload induced by transverse aortic constriction (TAC). In contrast, mice lacking ETA only in cardiomyocytes (CM-KO) were not protected. TAC led to a disturbed sympathetic nerve function as measured by cardiac norepinephrine (NE) tissue levels and [(124)I]-metaiodobenzylguanidine-PET, which was prevented in SN-KO. In a rat model of HF, ETAi improved cardiac and sympathetic nerve function. In cocultures of cardiomyocytes (CMs) and sympathetic neurons (SNs), endothelin-1 (ET1) led to a massive NE release and exaggerated CM hypertrophy compared with CM monocultures. ETA-deficient CMs gained a hypertrophic response through wild-type SNs, but ETA-deficient SNs failed to mediate exaggerated CM hypertrophy. Furthermore, ET1 mediated its effects indirectly via NE in CM-SN cocultures through adrenergic receptors and histone deacetylases, resulting in activation of the prohypertrophic transcription factor myocyte enhancer factor 2. In conclusion, sympathetic ETA amplifies ET1 effects on CMs through adrenergic signaling pathways. Thus, antiadrenergic therapies may blunt potentially beneficial effects of ETAi. Taken together, this may indicate that patients with ß blocker intolerance or disturbed sympathetic nerve function could be evaluated for a potential benefit from ETAi.

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.

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 ß-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.

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.

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.

EASIX (endothelial activation and stress index) predicts mortality in patients with coronary artery disease.

BACKGROUND: Coronary interventions reduce morbidity and mortality in patients with acute coronary syndrome. However, the risk of mortality for patients with coronary artery disease (CAD) additionally depends on their systemic endothelial health status. The 'Endothelial Activation and Stress Index' (EASIX) predicts endothelial complications and survival in diverse clinical settings. OBJECTIVE: We hypothesized that EASIX may predict mortality in patients with CAD. METHODS: In 1283 patients undergoing coronary catheterization (CC) and having a diagnosis of CAD, EASIX was measured within 52 days (range - 1 year to - 14 days) before CC and correlated with overall survival. In an independent validation cohort of 1934 patients, EASIXval was measured within 174 days (+ 28 days to + 11 years) after CC. RESULTS: EASIX predicted the risk of mortality after CC (per log2: hazard ratio (HR) 1.29, 95% confidence interval: [1.18-1.41], p < 0.001) in multivariable Cox regression analyses adjusting for age, sex, a high-grade coronary stenosis ≥ 90%, left ventricular ejection fraction, arterial hypertension and diabetes. In the independent cohort, EASIX correlated with EASIXval with rho = 0.7. The long-term predictive value of EASIXval was confirmed (per log2: HR 1.53, [1.42-1.64], p < 0.001) and could be validated by integrated Brier score and concordance index. Pre-established cut-offs (0.88-2.32) associated with increased mortality (cut-off 0.88: HR training: 1.63; HR validation: 1.67, p < 0.0001 and cut-off 2.32: HR training: 3.57; HR validation: 4.65, p < 0.0001). CONCLUSIONS: We validated EASIX as a potential biomarker to predict death of CAD patients, irrespective of the timing either before or after catheterization.

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.

Cardiovascular Events After Chimeric Antigen Receptor T-Cell Therapy for Advanced Hematologic Malignant Neoplasms: A Meta-Analysis.

Importance: The frequency and clinical phenotypes of cardiotoxic events in chimeric antigen receptor (CAR) T-cell recipients remain poorly understood given that landmark approval trials typically exclude patients with high-risk cardiovascular profiles and data from nontrial settings are scarce. Objective: To summarize the prevalence of adverse cardiovascular events among adults receiving CAR T-cell therapies for advanced hematologic malignant neoplasms. Data Sources: MEDLINE, Embase, Cochrane Library, and Google Scholar were systematically searched from database inception until February 26, 2024. Study Selection: Observational studies were included if they comprised adult CAR T-cell recipients with advanced hematologic malignant neoplasms and if they systematically evaluated cardiovascular complications. Data Extraction and Synthesis: Extraction of prespecified parameters related to the patient population, study design, and clinical events was performed at the study level by 2 independent reviewers in accordance with the Meta-Analysis of Observational Studies in Epidemiology (MOOSE) reporting guideline. Meta-analysis of single proportions was conducted using random-effect models with Freeman-Tukey double arcsine transformations to calculate pooled prevalence estimates. Sensitivity analysis was performed using generalized linear mixed models with logit transformations. Main Outcomes and Measures: Ventricular and supraventricular arrhythmias, heart failure events, reduction in left ventricular ejection fraction, myocardial infarction, and cardiovascular and all-cause mortality. Results: Thirteen studies comprising 1528 CAR T-cell recipients (median [IQR] age, 61 [58.7-63.0] years; 1016 males [66%]; 80% patients with lymphoma) were included. The median (IQR) duration of follow-up was 487 (294-530) days. On random-effects meta-analysis, we observed a pooled prevalence of 0.66% (95% CI, 0.00%-2.28%) for ventricular arrhythmia, 7.79% (95% CI, 4.87%-11.27%) for supraventricular arrhythmia, 8.68% (95% CI, 2.26%-17.97%) for left ventricular dysfunction, 3.87% (95% CI, 1.77%-6.62%) for heart failure events, 0.62% (95% CI, 0.02%-1.74%) for myocardial infarction, and 0.63% (95% CI, 0.13%-1.38%) for cardiovascular death. The pooled prevalence of all-cause mortality was 30.01% (95% CI, 19.49%-41.68%). Sensitivity analyses generated similar findings. Conclusions and Relevance: This meta-analysis found a low prevalence of ventricular arrhythmia, myocardial infarction, and cardiovascular death among CAR T-cell recipients over a short-term to midterm follow-up. Left ventricular dysfunction and supraventricular arrhythmia were the most commonly reported cardiovascular complications, suggesting that cardiovascular surveillance strategies should focus on decreases in ejection fraction and supraventricular arrhythmia.