Sacubitril/Valsartan Alleviates Cardiac Remodeling and Dysfunction in L-NAME-Induced Hypertension and Hypertensive Heart Disease.

There is ample evidence on the benefit of angiotensin receptor-neprilysin inhibitors (ARNIs) in heart failure, yet data regarding the potential protective action of ARNIs in hypertensive heart disease are sparse. The aim of this study was to show whether an ARNI exerts a protective effect in a model of Nω-nitro-L-arginine methyl ester (L-NAME)-induced hypertension with a hypertensive heart and to compare this potential benefit with an angiotensin-converting enzyme inhibitor, captopril. Five groups of adult male Wistar rats were studied (14 per group) for four weeks: untreated controls; ARNI (68 mg/kg/day); L-NAME (40 mg/kg/day); L-NAME treated with ARNI; and L-NAME treated with captopril (100 mg/kg/day). L-NAME administration induced hypertension, accompanied by increased left ventricular (LV) weight and fibrotic rebuilding of the LV in terms of increased concentration and content of hydroxyproline in insoluble collagen and in total collagen and with a histological finding of fibrosis. These alterations were associated with a compromised systolic and diastolic LV function. Treatment with either an ARNI or captopril reduced systolic blood pressure (SBP), alleviated LV hypertrophy and fibrosis, and prevented the development of both systolic and diastolic LV dysfunction. Moreover, the serum levels of prolactin and prolactin receptor were reduced significantly by ARNI and slightly by captopril. In conclusion, in L-NAME-induced hypertension, the dual inhibition of neprilysin and AT1 receptors by ARNI reduced SBP and prevented the development of LV hypertrophy, fibrosis, and systolic and diastolic dysfunction. These data suggest that ARNI could provide protection against LV structural remodeling and functional disorders in hypertensive heart disease.

Effect of sacubitril/valsartan on the hypertensive heart in continuous light-induced and lactacystin-induced pre-hypertension: Interactions with the renin-angiotensin-aldosterone system.

This study investigated whether sacubitril/valsartan or valsartan are able to prevent left ventricular (LV) fibrotic remodelling and dysfunction in two experimental models of pre-hypertension induced by continuous light (24 hours/day) exposure or by chronic lactacystin treatment, and how this potential protection interferes with the renin-angiotensin-aldosterone system (RAAS). Nine groups of three-month-old male Wistar rats were treated for six weeks as follows: untreated controls (C), sacubitril/valsartan (ARNI), valsartan (Val), continuous light (24), continuous light plus sacubitril/valsartan (24+ARNI) or valsartan (24+Val), lactacystin (Lact), lactacystin plus sacubitil/valsartan (Lact+ARNI) or plus valsartan (Lact+Val). Both the 24 and Lact groups developed a mild but significant systolic blood pressure (SBP) increase, LV hypertrophy and fibrosis, as well as LV systolic and diastolic dysfunction. Yet, no changes in serum renin-angiotensin were observed either in the 24 or Lact groups, though aldosterone was increased in the Lact group compared to the controls. In both models, sacubitril/valsartan and valsartan reduced elevated SBP, LV hypertrophy and fibrosis and attenuated LV systolic and diastolic dysfunction. Sacubitril/valsartan and valsartan increased the serum levels of angiotensin (Ang) II, Ang III, Ang IV, Ang 1-5, Ang 1-7 in the 24 and Lact groups and reduced aldosterone in the Lact group. We conclude that both continuous light exposure and lactacystin treatment induced normal-to-low serum renin-angiotensin models of pre-hypertension, whereas aldosterone was increased in lactacystin-induced pre-hypertension. The protection by ARNI or valsartan in the hypertensive heart in either model was related to the Ang II blockade and the protective Ang 1-7, while in lactacystin-induced pre-hypertension this protection seems to be additionally related to the reduced aldosterone level.

Cardiac miRNA expression during the development of chronic anthracycline-induced cardiomyopathy using an experimental rabbit model.

Background: Anthracycline cardiotoxicity is a well-known complication of cancer treatment, and miRNAs have emerged as a key driver in the pathogenesis of cardiovascular diseases. This study aimed to investigate the expression of miRNAs in the myocardium in early and late stages of chronic anthracycline induced cardiotoxicity to determine whether this expression is associated with the severity of cardiac damage. Method: Cardiotoxicity was induced in rabbits via daunorubicin administration (daunorubicin, 3 mg/kg/week; for five and 10 weeks), while the control group received saline solution. Myocardial miRNA expression was first screened using TaqMan Advanced miRNA microfluidic card assays, after which 32 miRNAs were selected for targeted analysis using qRT-PCR. Results: The first subclinical signs of cardiotoxicity (significant increase in plasma cardiac troponin T) were observed after 5 weeks of daunorubicin treatment. At this time point, 10 miRNAs (including members of the miRNA-34 and 21 families) showed significant upregulation relative to the control group, with the most intense change observed for miRNA-1298-5p (29-fold change, p < 0.01). After 10 weeks of daunorubicin treatment, when a further rise in cTnT was accompanied by significant left ventricle systolic dysfunction, only miR-504-5p was significantly (p < 0.01) downregulated, whereas 10 miRNAs were significantly upregulated relative to the control group; at this time-point, the most intense change was observed for miR-34a-5p (76-fold change). Strong correlations were found between the expression of multiple miRNAs (including miR-34 and mir-21 family and miR-1298-5p) and quantitative indices of toxic damage in both the early and late phases of cardiotoxicity development. Furthermore, plasma levels of miR-34a-5p were strongly correlated with the myocardial expression of this miRNA. Conclusion: To the best of our knowledge, this is the first study that describes alterations in miRNA expression in the myocardium during the transition from subclinical, ANT-induced cardiotoxicity to an overt cardiotoxic phenotype; we also revealed how these changes in miRNA expression are strongly correlated with quantitative markers of cardiotoxicity.

MicroRNAs in doxorubicin-induced cardiotoxicity: The DNA damage response.

Doxorubicin (DOX) is a chemotherapeutic drug widely used for cancer treatment, but its use is limited by cardiotoxicity. Although free radicals from redox cycling and free cellular iron have been predominant as the suggested primary pathogenic mechanism, novel evidence has pointed to topoisomerase II inhibition and resultant genotoxic stress as the more fundamental mechanism. Recently, a growing list of microRNAs (miRNAs) has been implicated in DOX-induced cardiotoxicity (DIC). This review summarizes miRNAs reported in the recent literature in the context of DIC. A particular focus is given to miRNAs that regulate cellular responses downstream to DOX-induced DNA damage, especially p53 activation, pro-survival signaling pathway inhibition (e.g., AMPK, AKT, GATA-4, and sirtuin pathways), mitochondrial dysfunction, and ferroptosis. Since these pathways are potential targets for cardioprotection against DOX, an understanding of how miRNAs participate is necessary for developing future therapies.

Lactacystin-induced kidney fibrosis: Protection by melatonin and captopril.

Lactacystin is a specific proteasome inhibitor that blocks the hydrolysis of intracellular proteins by ubiquitin/proteasome system inhibition. The administration of lactacystin to rats induced hypertension and remodeling of the left ventricle and aorta. This study tested whether lactacystin induces structural and fibrotic rebuilding of the kidneys and whether melatonin and captopril can prevent these potential changes. Six weeks of lactacystin administration to rats increased their average systolic blood pressure (SBP). In the kidneys, lactacystin reduced glomerular density, increased the glomerular tuft area, and enhanced hydroxyproline concentrations. It also elevated the intraglomerular proportion including the amounts of collagen (Col) I and Col III. Lactacystin also raised the tubulointerstitial amounts of Col I and the sum of Col I and Col III with no effect on vascular/perivascular collagen. Six weeks of captopril treatment reduced SBP, while melatonin had no effect. Both melatonin and captopril increased glomerular density, reduced the glomerular tuft area, and lowered the hydroxyproline concentration in the kidneys. Both drugs reduced the proportion and total amounts of intraglomerular and tubulointerstitial Col I and Col III. We conclude that chronic lactacystin treatment stimulated structural and fibrotic remodeling of the kidneys, and melatonin and captopril partly prevented these alterations. Considering the effect of lactacystin on both the heart and kidneys, chronic treatment with this drug may be a prospective model of cardiorenal damage suitable for testing pharmacological drugs as protective agents.

Sacubitril/Valsartan and Ivabradine Attenuate Left Ventricular Remodelling and Dysfunction in Spontaneously Hypertensive Rats: Different Interactions with the Renin-Angiotensin-Aldosterone System.

This study investigated whether sacubitril/valsartan and ivabradine are able to prevent left ventricular (LV) fibrotic remodelling and dysfunction in a rat experimental model of spontaneous hypertension (spontaneously hypertensive rats, SHRs) and whether this potential protection is associated with RAAS alterations. Five groups of three-month-old male Wistar rats and SHRs were treated for six weeks as follows: untreated Wistar controls, Wistar plus sacubitril/valsartan, SHR, SHR plus sacubitril/valsartan, and SHR plus ivabradine. The SHRs developed a systolic blood pressure (SBP) increase, LV hypertrophy and fibrosis, and LV systolic and diastolic dysfunction. However, no changes in serum RAAS were observed in SHRs compared with the controls. Elevated SBP in SHRs was decreased by sacubitril/valsartan but not by ivabradine, and only sacubitril/valsartan attenuated LV hypertrophy. Both sacubitril/valsartan and ivabradine reduced LV collagen content and attenuated LV systolic and diastolic dysfunction. Sacubitril/valsartan increased the serum levels of angiotensin (Ang) II, Ang III, Ang IV, Ang 1-5, Ang 1-7, and aldosterone, while ivabradine did not affect the RAAS. We conclude that the SHR is a normal-to-low serum RAAS model of experimental hypertension. While the protection of the hypertensive heart in SHRs by sacubitril/valsartan may be related to an Ang II blockade and the protective Ang 1-7, the benefits of ivabradine were not associated with RAAS modulation.

Characteristics and outcomes of patients admitted for acute heart failure in a single-centre study.

AIMS: Acute heart failure represents a medical condition with very high mortality. Accurate risk stratification can help physicians to improve the health care about these patients. The aim of our study was to characterize real-life patients admitted for acute heart failure in a specific region with one tertiary medical centre and to describe risk factors of short-term and long-term mortality. METHODS AND RESULTS: We performed a retrospective analysis of patients admitted from January 2017 to December 2017 to Department of cardiology of the tertiary medical centre University Hospital in Hradec Kralove. We identified 385 patients admitted for acute heart failure to the standard care and intensive care unit. The median of age was 74 years (IQR 67.5-80) and 34% of patients were female. Hospital admission was due to de novo heart failure in 222 (57.7%) patients. The most common comorbidities were arterial hypertension (77.7%), dyslipidaemia (67.3%) and coronary artery disease (63.1%). Coronary artery disease (52.7% of cases) and valve disease (28.1% of cases) were the most common aetiologies of heart failure. The all-cause in-hospital mortality was 12.7%, 30-day mortality was 14.6% and 1 year mortality was 34%. Among risk factors of in-hospital mortality, the most significant factors were haemodialysis during the hospitalization [odds ratio (OR) 15.82, 95% confidence interval (CI) 2.96-84.57, P = 0.0008], chronic heart failure (OR 4.27, 95% CI 1.66-11.03, P = 0.001) and STEMI as a precipitating factor of heart failure (OR 4.19, 95% CI 1.23-14.25, P = 0.023). Haemodialysis during the hospitalization (OR 4.28, 95% CI 1.17-15.61, P = 0.025) and the comorbidity depression and anxiety (OR 3.49, 95% CI 1.45-8.39, P = 0.005) were the most significant risk factors of long-term mortality. CONCLUSIONS: Our study confirms very high mortality rates among patients with acute heart failure underlying poor prognosis of these patients. Comorbidities (peripheral artery disease, atrial fibrillation, chronic heart failure and depression and anxiety), precipitating factors of heart failure (myocardial infarction with ST segment elevation), complications occurring during the hospitalization (acute kidney injury, pulmonary ventilation for respiratory failure and haemodialysis) and the age of patients should be included in the risk stratification of in-hospital, 30 day and 1 year mortality.

Primary prevention of chronic anthracycline cardiotoxicity with ACE inhibitor is temporarily effective in rabbits, but benefits wane in post-treatment follow-up.

Angiotensin-converting enzyme inhibitors (ACEis) have been used to treat anthracycline (ANT)-induced cardiac dysfunction, and they appear beneficial for secondary prevention in high-risk patients. However, it remains unclear whether they truly prevent ANT-induced cardiac damage and provide long-lasting cardioprotection. The present study aimed to examine the cardioprotective effects of perindopril on chronic ANT cardiotoxicity in a rabbit model previously validated with the cardioprotective agent dexrazoxane (DEX) with focus on post-treatment follow-up (FU). Chronic cardiotoxicity was induced by daunorubicin (DAU; 3 mg/kg/week for 10 weeks). Perindopril (0.05 mg/kg/day) was administered before and throughout chronic DAU treatment. After the completion of treatment, significant benefits were observed in perindopril co-treated animals, particularly full prevention of DAU-induced mortality and prevention or significant reductions in cardiac dysfunction, plasma cardiac troponin T (cTnT) levels, morphological damage, and most of the myocardial molecular alterations. However, these benefits significantly waned during 3 weeks of drug-free FU, which was not salvageable by administering a higher perindopril dose. In the longer (10-week) FU period, further worsening of left ventricular function and morphological damage occurred together with heart failure (HF)-related mortality. Continued perindopril treatment in the FU period did not reverse this trend but prevented HF-related mortality and reduced the severity of the progression of cardiac damage. These findings contrasted with the robust long-lasting protection observed previously for DEX in the same model. Hence, in the present study, perindopril provided only temporary control of ANT cardiotoxicity development, which may be associated with the lack of effects on ANT-induced and topoisomerase II ß (TOP2B)-dependent DNA damage responses in the heart.

Clinically Translatable Prevention of Anthracycline Cardiotoxicity by Dexrazoxane Is Mediated by Topoisomerase II Beta and Not Metal Chelation.

BACKGROUND: Anthracycline-induced heart failure has been traditionally attributed to direct iron-catalyzed oxidative damage. Dexrazoxane (DEX)-the only drug approved for its prevention-has been believed to protect the heart via its iron-chelating metabolite ADR-925. However, direct evidence is lacking, and recently proposed TOP2B (topoisomerase II beta) hypothesis challenged the original concept. METHODS: Pharmacokinetically guided study of the cardioprotective effects of clinically used DEX and its chelating metabolite ADR-925 (administered exogenously) was performed together with mechanistic experiments. The cardiotoxicity was induced by daunorubicin in neonatal ventricular cardiomyocytes in vitro and in a chronic rabbit model in vivo (n=50). RESULTS: Intracellular concentrations of ADR-925 in neonatal ventricular cardiomyocytes and rabbit hearts after treatment with exogenous ADR-925 were similar or exceeded those observed after treatment with the parent DEX. However, ADR-925 did not protect neonatal ventricular cardiomyocytes against anthracycline toxicity, whereas DEX exhibited significant protective effects (10-100 µmol/L; P<0.001). Unlike DEX, ADR-925 also had no significant impact on daunorubicin-induced mortality, blood congestion, and biochemical and functional markers of cardiac dysfunction in vivo (eg, end point left ventricular fractional shortening was 32.3±14.7%, 33.5±4.8%, 42.7±1.0%, and 41.5±1.1% for the daunorubicin, ADR-925 [120 mg/kg]+daunorubicin, DEX [60 mg/kg]+daunorubicin, and control groups, respectively; P<0.05). DEX, but not ADR-925, inhibited and depleted TOP2B and prevented daunorubicin-induced genotoxic damage. TOP2B dependency of the cardioprotective effects was probed and supported by experiments with diastereomers of a new DEX derivative. CONCLUSIONS: This study strongly supports a new mechanistic paradigm that attributes clinically effective cardioprotection against anthracycline cardiotoxicity to interactions with TOP2B but not metal chelation and protection against direct oxidative damage.

Prodrug of ICRF-193 provides promising protective effects against chronic anthracycline cardiotoxicity in a rabbit model in vivo.

The anthracycline (ANT) anticancer drugs such as doxorubicin or daunorubicin (DAU) can cause serious myocardial injury and chronic cardiac dysfunction in cancer survivors. A bisdioxopiperazine agent dexrazoxane (DEX) has been developed as a cardioprotective drug to prevent these adverse events, but it is uncertain whether it is the best representative of the class. The present study used a rabbit model of chronic ANT cardiotoxicity to examine another bisdioxopiperazine compound called GK-667 (meso-(butane-2,3-diylbis(2,6-dioxopiperazine-4,1-diyl))bis(methylene)-bis(2-aminoacetate) hydrochloride), a water-soluble prodrug of ICRF-193 (meso-4,4'-(butan-2,3-diyl)bis(piperazine-2,6-dione)), as a potential cardioprotectant. The cardiotoxicity was induced by DAU (3 mg/kg, intravenously, weekly, 10 weeks), and GK-667 (1 or 5 mg/kg, intravenously) was administered before each DAU dose. The treatment with GK-667 was well tolerated and provided full protection against DAU-induced mortality and left ventricular (LV) dysfunction (determined by echocardiography and LV catheterization). Markers of cardiac damage/dysfunction revealed minor cardiac damage in the group co-treated with GK-667 in the lower dose, whereas almost full protection was achieved with the higher dose. This was associated with similar prevention of DAU-induced dysregulation of redox and calcium homeostasis proteins. GK-667 dose-dependently prevented tumor suppressor p53 (p53)-mediated DNA damage response in the LV myocardium not only in the chronic experiment but also after single DAU administration. These effects appear essential for cardioprotection, presumably because of the topoisomerase IIß (TOP2B) inhibition provided by its active metabolite ICRF-193. In addition, GK-667 administration did not alter the plasma pharmacokinetics of DAU and its main metabolite daunorubicinol (DAUol) in rabbits in vivo. Hence, GK-667 merits further investigation as a promising drug candidate for cardioprotection against chronic ANT cardiotoxicity.

The Impact of microRNAs in Renin-Angiotensin-System-Induced Cardiac Remodelling.

Current knowledge on the renin-angiotensin system (RAS) indicates its central role in the pathogenesis of cardiovascular remodelling via both hemodynamic alterations and direct growth and the proliferation effects of angiotensin II or aldosterone resulting in the hypertrophy of cardiomyocytes, the proliferation of fibroblasts, and inflammatory immune cell activation. The noncoding regulatory microRNAs has recently emerged as a completely novel approach to the study of the RAS. A growing number of microRNAs serve as mediators and/or regulators of RAS-induced cardiac remodelling by directly targeting RAS enzymes, receptors, signalling molecules, or inhibitors of signalling pathways. Specifically, microRNAs that directly modulate pro-hypertrophic, pro-fibrotic and pro-inflammatory signalling initiated by angiotensin II receptor type 1 (AT1R) stimulation are of particular relevance in mediating the cardiovascular effects of the RAS. The aim of this review is to summarize the current knowledge in the field that is still in the early stage of preclinical investigation with occasionally conflicting reports. Understanding the big picture of microRNAs not only aids in the improved understanding of cardiac response to injury but also leads to better therapeutic strategies utilizing microRNAs as biomarkers, therapeutic agents and pharmacological targets.

Renin-Angiotensin-Aldosterone System: Friend or Foe-The Matter of Balance. Insight on History, Therapeutic Implications and COVID-19 Interactions.

The renin-angiotensin-aldosterone system (RAAS) ranks among the most challenging puzzles in cardiovascular medicine [...].

Ivabradine improves survival and attenuates cardiac remodeling in isoproterenol-induced myocardial injury.

This study investigated whether ivabradine, a selective If current inhibitor reducing heart rate (HR), is able to improve survival and prevent left ventricular (LV) remodeling in isoproterenol-induced heart damage. Wistar rats were treated for 6 weeks: controls (n = 10), ivabradine (10 mg/kg/day orally; n = 10), isoproterenol (5 mg/kg/day intraperitoneally; n = 40), and isoproterenol plus ivabradine (n = 40). Isoproterenol increased mortality, induced hypertrophy of both ventricles and LV fibrotic rebuilding, and reduced systolic blood pressure (SBP). Ivabradine significantly increased survival rate (by 120%) and prolonged average survival time (by 20%). Furthermore, ivabradine reduced LV weight and hydroxyproline content in soluble and insoluble collagen fraction, reduced HR and attenuated SBP decline. We conclude that ivabradine improved survival in isoproterenol-damaged hearts.

Ivabradine Ameliorates Kidney Fibrosis in L-NAME-Induced Hypertension.

Hypertension-induced renal injury is characterized by structural kidney alterations and function deterioration. Therapeutics for kidney protection are limited, thus novel renoprotectives in hypertension are being continuously sought out. Ivabradine, an inhibitor of the If current in the sinoatrial node reducing heart rate (HR), was shown to be of benefit in various cardiovascular pathologies. Yet, data regarding potential renoprotection by ivabradine in hypertension are sparse. Thirty-six adult male Wistar rats were divided into non-diseased controls and rats with NG-nitro-L-arginine methyl ester (L-NAME)-induced hypertension to assess ivabradine's site-specific effect on kidney fibrosis. After 4 weeks of treatment, L-NAME increased the average systolic blood pressure (SBP) (by 27%), decreased glomerular density (by 28%) and increased glomerular tuft area (by 44%). Moreover, L-NAME induced glomerular, tubulointerstitial, and vascular/perivascular fibrosis by enhancing type I collagen volume (16-, 19- and 25-fold, respectively). L-NAME also increased the glomerular type IV collagen volume and the tubular injury score (3- and 8-fold, respectively). Ivabradine decreased average SBP and HR (by 8 and 12%, respectively), increased glomerular density (by 57%) and reduced glomerular tuft area (by 30%). Importantly, ivabradine decreased type I collagen volume at all three of the investigated sites (by 33, 38, and 72%, respectively) and enhanced vascular/perivascular type III collagen volume (by 67%). Furthermore, ivabradine decreased the glomerular type IV collagen volume and the tubular injury score (by 63 and 34%, respectively). We conclude that ivabradine attenuated the alterations of glomerular density and tuft area and modified renal fibrosis in a site-specific manner in L-NAME-hypertension. It is suggested that ivabradine may be renoprotective in hypertensive kidney disease.

Antiarrhythmic Effects of Melatonin and Omega-3 Are Linked with Protection of Myocardial Cx43 Topology and Suppression of Fibrosis in Catecholamine Stressed Normotensive and Hypertensive Rats.

Cardiac ß-adrenergic overstimulation results in oxidative stress, hypertrophy, ischemia, lesion, and fibrosis rendering the heart vulnerable to malignant arrhythmias. We aimed to explore the anti-arrhythmic efficacy of the anti-oxidative and anti-inflammatory compounds, melatonin, and omega-3, and their mechanisms of actions in normotensive and hypertensive rats exposed to isoproterenol (ISO) induced ß-adrenergic overdrive. Eight-month-old, male SHR, and Wistar rats were injected during 7 days with ISO (cumulative dose, 118 mg/kg). ISO rats were either untreated or concomitantly treated with melatonin (10 mg/kg/day) or omega-3 (Omacor, 1.68 g/kg/day) until 60 days of ISO withdrawal and compared to non-ISO controls. Findings showed that both melatonin and omega-3 increased threshold current to induce ventricular fibrillation (VF) in ISO rats regardless of the strain. Prolonged treatment with these compounds resulted in significant suppression of ISO-induced extracellular matrix alterations, as indicated by reduced areas of diffuse fibrosis and decline of hydroxyproline, collagen-1, SMAD2/3, and TGF-ß1 protein levels. Importantly, the highly pro-arrhythmic ISO-induced disordered cardiomyocyte distribution of electrical coupling protein, connexin-43 (Cx43), and its remodeling (lateralization) were significantly attenuated by melatonin and omega-3 in Wistar as well as SHR hearts. In parallel, both compounds prevented the post-ISO-related increase in Cx43 variant phosphorylated at serine 368 along with PKCε, which are known to modulate Cx43 remodeling. Melatonin and omega-3 increased SOD1 or SOD2 protein levels in ISO-exposed rats of both strains. Altogether, the results indicate that anti-arrhythmic effects of melatonin and omega-3 might be attributed to the protection of myocardial Cx43 topology and suppression of fibrosis in the setting of oxidative stress induced by catecholamine overdrive in normotensive and hypertensive rats.

Investigation of Structure-Activity Relationships of Dexrazoxane Analogs Reveals Topoisomerase IIß Interaction as a Prerequisite for Effective Protection against Anthracycline Cardiotoxicity.

Bisdioxopiperazine agent dexrazoxane (ICRF-187) has been the only effective and approved drug for prevention of chronic anthracycline cardiotoxicity. However, the structure-activity relationships (SARs) of its cardioprotective effects remain obscure owing to limited investigation of its derivatives/analogs and uncertainties about its mechanism of action. To fill these knowledge gaps, we tested the hypothesis that dexrazoxane derivatives exert cardioprotection via metal chelation and/or modulation of topoisomerase IIß (Top2B) activity in chronic anthracycline cardiotoxicity. Dexrazoxane was alkylated in positions that should not interfere with the metal-chelating mechanism of cardioprotective action; that is, on dioxopiperazine imides or directly on the dioxopiperazine ring. The protective effects of these agents were assessed in vitro in neonatal cardiomyocytes. All studied modifications of dexrazoxane molecule, including simple methylation, were found to abolish the cardioprotective effects. Because this challenged the prevailing mechanistic concept and previously reported data, the two closest derivatives [(±)-4,4'-(propane-1,2-diyl)bis(1-methylpiperazine-2,6-dione) and 4-(2-(3,5-dioxopiperazin-1-yl)ethyl)-3-methylpiperazine-2,6-dione] were thoroughly scrutinized in vivo using a rabbit model of chronic anthracycline cardiotoxicity. In contrast to dexrazoxane, both compounds failed to protect the heart, as demonstrated by mortality, cardiac dysfunction, and myocardial damage parameters, although the pharmacokinetics and metal-chelating properties of their metabolites were comparable to those of dexrazoxane. The loss of cardiac protection was shown to correlate with their abated potential to inhibit and deplete Top2B both in vitro and in vivo. These findings suggest a very tight SAR between bisdioxopiperazine derivatives and their cardioprotective effects and support Top2B as a pivotal upstream druggable target for effective cardioprotection against anthracycline cardiotoxicity. SIGNIFICANCE STATEMENT: This study has revealed the previously unexpected tight structure-activity relationships of cardioprotective effects in derivatives of dexrazoxane, which is the only drug approved for the prevention of cardiomyopathy and heart failure induced by anthracycline anticancer drugs. The data presented in this study also strongly argue against the importance of metal-chelating mechanisms for the induction of this effect and support the viability of topoisomerase IIß as an upstream druggable target for effective and clinically translatable cardioprotection.

In vitro and in vivo investigation of cardiotoxicity associated with anticancer proteasome inhibitors and their combination with anthracycline.

Although proteasome inhibitors (PIs) are modern targeted anticancer drugs, they have been associated with a certain risk of cardiotoxicity and heart failure (HF). Recently, PIs have been combined with anthracyclines (ANTs) to further boost their anticancer efficacy. However, this raised concerns regarding cardiac safety, which were further supported by several in vitro studies on immature cardiomyocytes. In the present study, we investigated the toxicity of clinically used PIs alone (bortezomib (BTZ), carfilzomib (CFZ)) as well as their combinations with an ANT (daunorubicin (DAU)) in both neonatal and adult ventricular cardiomyocytes (NVCMs and AVCMs) and in a chronic rabbit model of DAU-induced HF. Using NVCMs, we found significant cytotoxicity of both PIs around their maximum plasma concentration (cmax) as well as significant augmentation of DAU cytotoxicity. In AVCMs, BTZ did not induce significant cytotoxicity in therapeutic concentrations, whereas the toxicity of CFZ was significant and more profound. Importantly, neither PI significantly augmented the cardiotoxicity of DAU despite even more profound proteasome-inhibitory activity in AVCMs compared with NVCMs. Furthermore, in young adult rabbits, no significant augmentation of chronic ANT cardiotoxicity was noted with respect to any functional, morphological, biochemical or molecular parameter under study, despite significant inhibition of myocardial proteasome activity. Our experimental data show that combination of PIs with ANTs is not accompanied by an exaggerated risk of cardiotoxicity and HF in young adult animal cardiomyocytes and hearts.

Cardiac Troponins are Among Targets of Doxorubicin-Induced Cardiotoxicity in hiPCS-CMs.

Modern diagnostic strategies for early recognition of cancer therapeutics-related cardiac dysfunction involve cardiac troponins measurement. Still, the role of other markers of cardiotoxicity is still unclear. The present study was designed to investigate dynamics of response of human cardiomyocytes derived from induced pluripotent stem cells (hiPCS-CMs) to doxorubicin with the special emphasis on their morphological changes in relation to expression and organization of troponins. The hiPCS-CMs were treated with doxorubicin concentrations (1 and 0.3 µM) for 48 h and followed for next up to 6 days. Exposure of hiPCS-CMs to 1 µM doxorubicininduced suppression of both cardiac troponin T (cTnT) and cardiac troponin I (cTnI) gene expression. Conversely, lower 0.3 µM doxorubicin concentration produced no significant changes in the expression of aforementioned genes. However, the intracellular topography, arrangement, and abundance of cardiac troponin proteins markedly changed after both doxorubicin concentrations. In particular, at 48 h of treatment, both cTnT and cTnI bundles started to reorganize, with some of them forming compacted shapes extending outwards and protruding outside the cells. At later intervals (72 h and onwards), the whole troponin network collapsed and became highly disorganized following, to some degree, overall changes in the cellular shape. Moreover, membrane permeability of cardiomyocytes was increased, and intracellular mitochondrial network rearranged and hypofunctional. Together, our results demonstrate complex effects of clinically relevant doxorubicin concentrations on hiPCS-CM cells including changes in cTnT and cTnI, but also in other cellular compartments contributing to the overall cytotoxicity of this class of cytostatics.

Lisinopril reverses behavioural alterations in spontaneously hypertensive rats.

This study investigated the effect of lisinopril (angiotensin-converting enzyme inhibitor) on potential behavioural alterations in spontaneously hypertensive rats (SHR). Three groups of 15-17-week-old rats were investigated for 2 weeks: Wistar control group, SHR group and SHR+lisinopril group. Systolic blood pressure (SBP) was normal in Wistar rats, SHR expressed hypertension and lisinopril normalized the SBP. We observed increased time spent in and increased frequency of entries to the central area of the open field in SHR, while lisinopril induced a trend to reduce the time spent in the central area of the open field and reduced the frequency of entries there. There was a positive correlation between SBP and reduced anxiety-like behaviour in normotensive rats; no correlations in the SHR or SHR+lisinopril groups were observed. We conclude that lisinopril normalized the increase in SBP and partly reversed the alterations of anxiety-like behaviour in SHR.

Effect of Ivabradine on a Hypertensive Heart and the Renin-Angiotensin-Aldosterone System in L-NAME-Induced Hypertension.

Ivabradine, the selective inhibitor of the If current in the sinoatrial node, exerts cardiovascular protection by its bradycardic effect and potentially pleiotropic actions. However, there is a shortage of data regarding ivabradine's interaction with the renin-angiotensin-aldosterone system (RAAS). This study investigated whether ivabradine is able to protect a hypertensive heart in the model of L-NAME-induced hypertension and to interfere with the RAAS. Four groups (n = 10/group) of adult male Wistar rats were treated as follows for four weeks: control, ivabradine (10 mg/kg/day), L-NAME (40 mg/kg/day), and L-NAME plus ivabradine. L-NAME administration increased systolic blood pressure (SBP) and left ventricular (LV) weight, enhanced hydroxyproline concentration in the LV, and deteriorated the systolic and diastolic LV function. Ivabradine reduced heart rate (HR) and SBP, and improved the LV function. The serum concentrations of angiotensin Ang 1⁻8 (Ang II), Ang 1⁻5, Ang 1⁻7, Ang 1⁻10, Ang 2⁻8, and Ang 3⁻8 were decreased in the L-NAME group and ivabradine did not modify them. The serum concentration of aldosterone and the aldosterone/Ang II ratio were enhanced by L-NAME and ivabradine reduced these changes. We conclude that ivabradine improved the LV function of the hypertensive heart in L-NAME-induced hypertension. The protective effect of ivabradine might have been associated with the reduction of the aldosterone level.