Adelino F. Leite-Moreira

Hypophosphorylation of the Stiff N2B Titin Isoform Raises Cardiomyocyte Resting Tension in Failing Human Myocardium

High diastolic stiffness of failing myocardium results from interstitial fibrosis and elevated resting tension (Fpassive) of cardiomyocytes. A shift in titin isoform expression from N2BA to N2B isoform, lower overall phosphorylation of titin, and a shift in titin phosphorylation from N2B to N2BA isoform can raise Fpassive of cardiomyocytes. In left ventricular biopsies of heart failure (HF) patients, aortic stenosis (AS) patients, and controls (CON), we therefore related Fpassive of isolated cardiomyocytes to expression of titin isoforms and to phosphorylation of titin and titin isoforms. Biopsies were procured by transvascular technique (44 HF, 3 CON), perioperatively (25 AS, 4 CON), or from explanted hearts (4 HF, 8 CON). None had coronary artery disease. Isolated, permeabilized cardiomyocytes were stretched to 2.2-&mgr;m sarcomere length to measure Fpassive. Expression and phosphorylation of titin isoforms were analyzed using gel electrophoresis with ProQ Diamond and SYPRO Ruby stains and reported as ratio of titin (N2BA/N2B) or of phosphorylated titin (P-N2BA/P-N2B) isoforms. Fpassive was higher in HF (6.1±0.4 kN/m2) than in CON (2.3±0.3 kN/m2; P<0.01) or in AS (2.2±0.2 kN/m2; P<0.001). Titin isoform expression differed between HF (N2BA/N2B=0.73±0.06) and CON (N2BA/N2B=0.39±0.05; P<0.001) and was comparable in HF and AS (N2BA/N2B=0.59±0.06). Overall titin phosphorylation was also comparable in HF and AS, but relative phosphorylation of the stiff N2B titin isoform was significantly lower in HF (P-N2BA/P-N2B=0.77±0.05) than in AS (P-N2BA/P-N2B=0.54±0.05; P<0.01). Relative hypophosphorylation of the stiff N2B titin isoform is a novel mechanism responsible for raised Fpassive of human HF cardiomyocytes.

Afterload induced changes in myocardial relaxation: A mechanism for diastolic dysfunction

BACKGROUND Diastolic left ventricular (LV) dysfunction manifests as an upward shift of the diastolic pressure-volume relation. One of the possible causes of diastolic LV dysfunction is incomplete myocardial relaxation. It is well known that high afterload slows myocardial relaxation. This contribution investigated to what extent afterload elevation could also affect LV filling pressures including end-diastolic LV pressure (LVP). METHODS Selective, beat-to-beat elevations of afterload were induced in anaesthetised open-chest rabbits (n = 9) by abrupt narrowing of the ascending aorta during the diastole of the preceding heartbeat. This was performed with physiological heart rate and blood pressure. RESULTS These interventions increased systolic LVP from 90 +/- 3 mm Hg at baseline to 103 +/- 4, 123 +/- 5, 139 +/- 5 and 154 +/- 6 mm Hg. The last intervention was a total aortic occlusion inducing a first beat isovolumetric contraction. Smaller afterload elevations decreased tau (accelerated LVP fall) and did not elevate diastolic pressure-internal diameter relation (P-ID). Larger afterload elevations increased tau (decelerated LVP fall), induced an upward shift of the diastolic P-ID and increased end-diastolic LVP. Effects of afterload on end-diastolic LVP were correlated with effects on tau (r = 0.89; P < 0.01). Incomplete relaxation or load-dependent residual active state appeared to be the mechanism for this diastolic dysfunction. Similar findings were made retrospectively in dogs instrumented with circumferential segment length gauges (n = 16). CONCLUSIONS Diastolic LV dysfunction was induced by elevated afterload in healthy hearts of rabbits and dogs. If this mechanism could be shown to be operative in the failing heart, reversal of diastolic dysfunction should contribute to the beneficial effects of vasodilating and inotropic therapy on pulmonary congestion.

Low Myocardial Protein Kinase G Activity in Heart Failure With Preserved Ejection Fraction

Background— Prominent features of myocardial remodeling in heart failure with preserved ejection fraction (HFPEF) are high cardiomyocyte resting tension (Fpassive) and cardiomyocyte hypertrophy. In experimental models, both reacted favorably to raised protein kinase G (PKG) activity. The present study assessed myocardial PKG activity, its downstream effects on cardiomyocyte Fpassive and cardiomyocyte diameter, and its upstream control by cyclic guanosine monophosphate (cGMP), nitrosative/oxidative stress, and brain natriuretic peptide (BNP). To discern altered control of myocardial remodeling by PKG, HFPEF was compared with aortic stenosis and HF with reduced EF (HFREF). Methods and Results— Patients with HFPEF (n=36), AS (n=67), and HFREF (n=43) were free of coronary artery disease. More HFPEF patients were obese (P<0.05) or had diabetes mellitus (P<0.05). Left ventricular myocardial biopsies were procured transvascularly in HFPEF and HFREF and perioperatively in aortic stenosis. Fpassive was measured in cardiomyocytes before and after PKG administration. Myocardial homogenates were used for assessment of PKG activity, cGMP concentration, proBNP-108 expression, and nitrotyrosine expression, a measure of nitrosative/oxidative stress. Additional quantitative immunohistochemical analysis was performed for PKG activity and nitrotyrosine expression. Lower PKG activity in HFPEF than in aortic stenosis (P<0.01) or HFREF (P<0.001) was associated with higher cardiomyocyte Fpassive (P<0.001) and related to lower cGMP concentration (P<0.001) and higher nitrosative/oxidative stress (P<0.05). Higher Fpassive in HFPEF was corrected by in vitro PKG administration. Conclusions— Low myocardial PKG activity in HFPEF was associated with raised cardiomyocyte Fpassive and was related to increased myocardial nitrosative/oxidative stress. The latter was probably induced by the high prevalence in HFPEF of metabolic comorbidities. Correction of myocardial PKG activity could be a target for specific HFPEF treatment.

Diabetic cardiomyopathy: understanding the molecular and cellular basis to progress in diagnosis and treatment.

Diabetes mellitus is an important and prevalent risk factor for congestive heart failure. Diabetic cardiomyopathy has been defined as ventricular dysfunction that occurs in diabetic patients independent of a recognized cause such as coronary artery disease or hypertension. The disease course consists of a hidden subclinical period, during which cellular structural insults and abnormalities lead initially to diastolic dysfunction, later to systolic dysfunction, and eventually to heart failure. Left ventricular hypertrophy, metabolic abnormalities, extracellular matrix changes, small vessel disease, cardiac autonomic neuropathy, insulin resistance, oxidative stress, and apoptosis are the most important contributors to diabetic cardiomyopathy onset and progression. Hyperglycemia is a major etiological factor in the development of diabetic cardiomyopathy. It increases the levels of free fatty acids and growth factors and causes abnormalities in substrate supply and utilization, calcium homeostasis, and lipid metabolism. Furthermore, it promotes excessive production and release of reactive oxygen species, which induces oxidative stress leading to abnormal gene expression, faulty signal transduction, and cardiomyocytes apoptosis. Stimulation of connective tissue growth factor, fibrosis, and the formation of advanced glycation end-products increase the stiffness of the diabetic hearts. Despite all the current information on diabetic cardiomyopathy, translational research is still scarce due to limited human myocardial tissue and most of our knowledge is extrapolated from animals. This paper aims to elucidate some of the molecular and cellular pathophysiologic mechanisms, structural changes, and therapeutic strategies that may help struggle against diabetic cardiomyopathy.

Ghrelin, des-acyl ghrelin and obestatin: Three pieces of the same puzzle

The major active product of ghrelin gene is a 28-amino acid peptide acylated at the serine 3 position with an octanoyl group, called simply ghrelin. Ghrelin has a multiplicity of physiological functions, affecting GH release, food intake, energy and glucose homeostasis, gastrointestinal, cardiovascular, pulmonary and immune function, cell proliferation and differentiation and bone physiology. Nevertheless, recent developments have shown that ghrelin gene can generate various bioactive molecules besides ghrelin, mainly des-acyl ghrelin and obestatin, obtained from alternative splicing or from extensive post-translational modification. Although their receptors have not yet been identified, they have already proven to be active, having intriguingly subtle but opposite physiological actions to ghrelin. This suggests the existence of a novel endocrine system with multiple effector elements which not only may have opposite actions but may regulate the action of each other. In this review, we summarize the steps which lead to the production of the different ghrelin gene products and examine the most significant differences between them in terms of structure and actions.

Recommendations on pre-hospital & early hospital management of acute heart failure: a consensus paper from the Heart Failure Association of the European Society of Cardiology, the European Society of Emergency Medicine and the Society of Academic Emergenc: Recommendations on pre-hospital & early hospital management of acute heart failure

Acute heart failure is a fatal syndrome. Emergency physicians, cardiologists, intensivists, nurses and other health care providers have to cooperate to provide optimal benefit. However, many treatment decisions are opinion‐based and few are evidenced‐based. This consensus paper provides guidance to practicing physicians and nurses to manage acute heart failure in the pre‐hospital and hospital setting. Criteria of hospitalization and of discharge are described. Gaps in knowledge and perspectives in the management of acute heart failure are also detailed. This consensus paper on acute heart failure might help enable contiguous practice.

Diabetes Mellitus Worsens Diastolic Left Ventricular Dysfunction in Aortic Stenosis Through Altered Myocardial Structure and Cardiomyocyte Stiffness

Background— Aortic stenosis (AS) and diabetes mellitus (DM) are frequent comorbidities in aging populations. In heart failure, DM worsens diastolic left ventricular (LV) dysfunction, thereby adversely affecting symptoms and prognosis. Effects of DM on diastolic LV function were therefore assessed in aortic stenosis, and underlying myocardial mechanisms were identified. Methods and Results— Patients referred for aortic valve replacement were subdivided into patients with AS and no DM (AS; n=46) and patients with AS and DM (AS-DM; n=16). Preoperative Doppler echocardiography and hemodynamics were implemented with perioperative LV biopsies. Histomorphometry and immunohistochemistry quantified myocardial collagen volume fraction and myocardial advanced glycation end product deposition. Isolated cardiomyocytes were stretched to 2.2-&mgr;m sarcomere length to measure resting tension (Fpassive). Expression and phosphorylation of titin isoforms were analyzed with gel electrophoresis with ProQ Diamond and SYPRO Ruby stains. Reduced LV end-diastolic distensibility in AS-DM was evident from higher LV end-diastolic pressure (21±1 mm Hg for AS versus 28±4 mm Hg for AS-DM; P=0.04) at comparable LV end-diastolic volume index and attributed to higher myocardial collagen volume fraction (AS, 12.9±1.1% versus AS-DM, 18.2±2.6%; P<0.001), more advanced glycation end product deposition in arterioles, venules, and capillaries (AS, 14.4±2.1 score per 1 mm2 versus AS-DM, 31.4±6.1 score per 1 mm2; P=0.03), and higher Fpassive (AS, 3.5±1.7 kN/m2 versus AS-DM, 5.1±0.7 kN/m2; P=0.04). Significant hypophosphorylation of the stiff N2B titin isoform in AS-DM explained the higher Fpassive and normalization of Fpassive after in vitro treatment with protein kinase A. Conclusions— Worse diastolic LV dysfunction in AS-DM predisposes to heart failure and results from more myocardial fibrosis, more intramyocardial vascular advanced glycation end product deposition, and higher cardiomyocyte Fpassive, which was related to hypophosphorylation of the N2B titin isoform.

Recommendations on pre-hospital and early hospital management of acute heart failure : a consensus paper from the Heart Failure Association of the European Society of Cardiology, the European Society of Emergency Medicine and the Society of Academic Emergency Medicine - short version

Despite several critical steps forward in the management of chronic heart failure (CHF), the area of acute heart failure (AHF) has remained relatively stagnant. As stated in the updated ESC HF guidelines, clinicians responsible for managing patients with AHF must frequently make treatment decisions without adequate evidence, usually on the basis of expert opinion consensus.2 Specifically, the treatment of acute HF remains largely opinion-based with little good evidence to guide therapy. Acute heart failure is a syndrome in which emergency physicians, cardiologists, intensivists, nurses, and other healthcare providers have to cooperate to provide ‘rapid’ benefit to the patients. We hereby would like to underscore the wider experience grown in different settings of the area of intensive care on acute heart failure, actually larger and more composite than that got in specialized Care Units. The distillate of such different experiences is discussed and integrated in the present document. Hence, the authors of this consensus paper believe a common working definition of AHF covering all dimensions and modes of presentations has to be made, with the understanding that most AHF presentations are either acute decompensations of chronic underlying HF or the abrupt onset of dyspnoea associated with significantly elevated blood pressure. Secondly, recent data show that, much like acute coronary syndrome, AHF might have a ‘time to therapy’ concept. Accordingly, ‘pre-hospital’ management is considered a critical component of care. Thirdly, most patients with AHF have normal or high blood pressure at presentation, and are admitted with symptoms and/or signs of congestion. This is in contradiction to the presentation where low cardiac output leads to symptomatic hypotension and signs/symptoms of hypoperfusion, a circumstance that is relatively rare, present in coronary care unit/intensive care unit (CCU/ICU) but associated with a particularly poor outcome. Hence, it is important to note that appropriate therapy requires appropriate identification of the specific AHF phenotype.3 The aim of the current paper is not to replace guidelines, but, to provide contemporary perspective for early hospital management within the context of the most recent data and to provide guidance, based on expert opinions, to practicing physicians and other healthcare professionals (Figure 1). We believe that the experience accrued in the different settings from the emergency department through to the ICU/CCU is collectivel valuable in determining how best to manage the patients with AHF. Herein, a shortened version mainly including group recommendations is provided. Full version of the consensus paper is provided as Supplementary material online.

Apelin decreases myocardial injury and improves right ventricular function in monocrotaline-induced pulmonary hypertension

We investigated the endogenous production of apelin and the cardiac and pulmonary effects of its chronic administration in monocrotaline (MCT)-induced pulmonary hypertension (PH). Male Wistar rats were injected with MCT (60 mg/kg sc) or vehicle (day 0). One week later, these animals were randomly treated during 17 days with pyroglutamylated apelin-13 (Pyr-AP13; 200 microg*kg(-1)*day(-1) ip) or a similar volume of saline, resulting in four groups: sham (n = 11), sham-AP (n = 11), MCT (n = 16), and MCT-AP (n = 13). On day 25, right ventricular (RV) and left ventricular (LV) hemodynamic and morphometric parameters were assessed. Tissue and plasma samples were collected for histological and molecular analysis. When compared with sham, the MCT group presented a significant increase of RV mass (166 +/- 38%), diameter of cardiomyocyte (40 +/- 10%), myocardial fibrosis (95 +/- 20%), peak systolic pressure (99 +/- 22%), peak rate of ventricular pressure rise (dP/dt(max); 74 +/- 24%), peak rate of ventricular pressure decline (dP/dt(min); 73 +/- 19%), and time constant tau (55 +/- 16%). In these animals, RV expression of apelin (-73 +/- 10%) and its receptor APJ (-61 +/- 20%) was downregulated, whereas mRNA expression of type B natriuretic peptide (9,606 +/- 713%), angiotensinogen (191 +/- 147%), endothelin-1 (RV, 497 +/- 156%; and LV, 799 +/- 309%), plasmatic levels of apelin (104 +/- 48%), and angiotensin 1-7 (161 +/- 151%) were increased. Chronic treatment with Pyr-AP13 significantly attenuated or normalized these changes, preventing apelin-APJ mRNA downregulation and PH-induced neurohumoral activation of several vasoconstrictors, which exacerbates apelin-APJ vasodilator effects. Therefore, apelin delayed the progression of RV hypertrophy and diastolic dysfunction. Together, these observations suggest that the apelin-APJ system may play an important role in the pathophysiology of PH, representing a potential therapeutic target since it significantly attenuates RV overload and PH-induced neurohumoral activation.

Myocardial Titin Hypophosphorylation Importantly Contributes to Heart Failure With Preserved Ejection Fraction in a Rat Metabolic Risk Model

Background—Obesity and diabetes mellitus are important metabolic risk factors and frequent comorbidities in heart failure with preserved ejection fraction. They contribute to myocardial diastolic dysfunction (DD) through collagen deposition or titin modification. The relative importance for myocardial DD of collagen deposition and titin modification was investigated in obese, diabetic ZSF1 rats after heart failure with preserved ejection fraction development at 20 weeks. Methods and Results—Four groups of rats (Wistar-Kyoto, n=11; lean ZSF1, n=11; obese ZSF1, n=11, and obese ZSF1 with high-fat diet, n=11) were followed up for 20 weeks with repeat metabolic, renal, and echocardiographic evaluations and hemodynamically assessed at euthanization. Myocardial collagen, collagen cross-linking, titin isoforms, and phosphorylation were also determined. Resting tension (Fpassive)–sarcomere length relations were obtained in small muscle strips before and after KCl–KI treatment, which unanchors titin and allows contributions of titin and extracellular matrix to Fpassive to be discerned. At 20 weeks, the lean ZSF1 group was hypertensive, whereas both obese ZSF1 groups were hypertensive and diabetic. Only the obese ZSF1 groups had developed heart failure with preserved ejection fraction, which was evident from increased lung weight, preserved left ventricular ejection fraction, and left ventricular DD. The underlying myocardial DD was obvious from high muscle strip stiffness, which was largely (±80%) attributable to titin hypophosphorylation. The latter occurred specifically at the S3991 site of the elastic N2Bus segment and at the S12884 site of the PEVK segment. Conclusions—Obese ZSF1 rats developed heart failure with preserved ejection fraction during a 20-week time span. Titin hypophosphorylation importantly contributed to the underlying myocardial DD.