Physiological Hypertrophy Research Articles

Neddylation is required for perinatal cardiac development through stimulation of metabolic maturation

Cardiac maturation is crucial for postnatal cardiac development and is increasingly known to be regulated by a series of transcription factors. However, post-translational mechanisms regulating this process remain unclear. Here we report the indispensable role of neddylation in cardiac maturation. Mosaic deletion of NAE1, an essential enzyme for neddylation, in neonatal hearts results in the rapid development of cardiomyopathy and heart failure. NAE1 deficiency disrupts transverse tubule formation, inhibits physiological hypertrophy, and represses fetal-to-adult isoform switching, thus culminating in cardiomyocyte immaturation. Mechanistically, we find that neddylation is needed for the perinatal metabolic transition from glycolytic to oxidative metabolism in cardiomyocytes. Further, we show that HIF1α is a putative neddylation target and that inhibition of neddylation accumulates HIF1α and impairs fatty acid utilization and bioenergetics in cardiomyocytes. Together, our data show neddylation is required for cardiomyocyte maturation through promoting oxidative metabolism in the developing heart.

Cardiovascular Property of Resistance Training With an Emphasis on PI3K/AKT1 Genes Expression in Type 2 Diabetic Rats

Background: The potential role of exercise in physiological cardiac hypertrophy is rooted in both hormonal and genetic components. Objectives: The aim of this study was to determine the impact of resistance exercise on the expression of PI3K and AKT1 in cardiac tissue of type 2 diabetes (T2D) rats and their physiological cardiac hypertrophy. Methods: First, 21 male Wistar rats (220±20 g) were obese with 6-week high-fat diet (HFD) and were randomly assigned into non-diabetes, control T2D, and exercise diabetes groups. After inducing obesity, T2D was induced by intraperitoneal injection of streptozotocin (25 mg/kg) for diabetes groups. Rats in the exercise group completed a 6-week resistance exercise program, 5 sessions per week. PI3K/AKT1 expression and the weight ratio of left ventricular to heart, heart to body, and left ventricular to body were compared by analysis of variance (ANOVA) between groups. Results: In response to the induction of diabetes, the expression of PI3K/AKT1 in heart tissue decreased significantly compared to that of non-diabetic rats (P=0.001 and P=0.001, respectively). Further, resistance training led to a significant increase in PI3K expression (P=0.028) and AKT1 (P=0.032) and the weight ratio of left ventricular to heart (P=0.001), heart to the body (P=0.001), and left ventricular to the body (P=0.001) compared to control diabetic rats. Conclusion: Resistance training is associated with physiological cardiac hypertrophy in diabetic rats, and this improvement may be attributed to the PI3K/AKT1 signaling pathway.

Detailed characterization of balanced intense exercise training induced right ventricular alterations reveals physiological myocardial hypertrophy with improved contractility in a rodent model

Detailed characterization of balanced intense exercise training induced right ventricular alterations reveals physiological myocardial hypertrophy with improved contractility in a rodent model

Cardiomyocyte BRAF is a key signalling intermediate in cardiac hypertrophy in mice.

Cardiac hypertrophy is necessary for the heart to accommodate an increase in workload. Physiological, compensated hypertrophy (e.g. with exercise) is reversible and largely due to cardiomyocyte hypertrophy. Pathological hypertrophy (e.g. with hypertension) is associated with additional features including increased fibrosis and can lead to heart failure. RAF kinases (ARAF/BRAF/RAF1) integrate signals into the extracellular signal-regulated kinase 1/2 cascade, a pathway implicated in cardiac hypertrophy, and activation of BRAF in cardiomyocytes promotes compensated hypertrophy. Here, we used mice with tamoxifen-inducible cardiomyocyte-specific BRAF knockout (CM-BRAFKO) to assess the role of BRAF in hypertension-associated cardiac hypertrophy induced by angiotensin II (AngII; 0.8 mg/kg/d, 7 d) and physiological hypertrophy induced by phenylephrine (40 mg/kg/d, 7 d). Cardiac dimensions/functions were measured by echocardiography with histological assessment of cellular changes. AngII promoted cardiomyocyte hypertrophy and increased fibrosis within the myocardium (interstitial) and around the arterioles (perivascular) in male mice; cardiomyocyte hypertrophy and interstitial (but not perivascular) fibrosis were inhibited in mice with CM-BRAFKO. Phenylephrine had a limited effect on fibrosis but promoted cardiomyocyte hypertrophy and increased contractility in male mice; cardiomyocyte hypertrophy was unaffected in mice with CM-BRAFKO, but the increase in contractility was suppressed and fibrosis increased. Phenylephrine induced a modest hypertrophic response in female mice and, in contrast with the males, tamoxifen-induced loss of cardiomyocyte BRAF reduced cardiomyocyte size, had no effect on fibrosis and increased contractility. The data identify BRAF as a key signalling intermediate in both physiological and pathological hypertrophy in male mice, and highlight the need for independent assessment of gene function in females.

METTL14 is required for exercise-induced cardiac hypertrophy and protects against myocardial ischemia-reperfusion injury

RNA m6A modification is the most widely distributed RNA methylation and is closely related to various pathophysiological processes. Although the benefit of regular exercise on the heart has been well recognized, the role of RNA m6A in exercise training and exercise-induced physiological cardiac hypertrophy remains largely unknown. Here, we show that endurance exercise training leads to reduced cardiac mRNA m6A levels. METTL14 is downregulated by exercise, both at the level of RNA m6A and at the protein level. In vivo, wild-type METTL14 overexpression, but not MTase inactive mutant METTL14, blocks exercise-induced physiological cardiac hypertrophy. Cardiac-specific METTL14 knockdown attenuates acute ischemia-reperfusion injury as well as cardiac dysfunction in ischemia-reperfusion remodeling. Mechanistically, silencing METTL14 suppresses Phlpp2 mRNA m6A modifications and activates Akt-S473, in turn regulating cardiomyocyte growth and apoptosis. Our data indicates that METTL14 plays an important role in maintaining cardiac homeostasis. METTL14 downregulation represents a promising therapeutic strategy to attenuate cardiac remodeling.

Abstract 13809: Multiparametric CMR Tissue Characterization Distinguishes Pathological From Physiological Cardiac Hypertrophy and Correlates With CPET Findings

Introduction: Physiological and pathological cardiac hypertrophy differ in terms of mechanisms, phenotypes, and outcomes. We aimed to characterize the cardiac tissue phenotype of athletes and HF patients. Methods: Prospectively enrolled participants underwent CMR and CPET. HF patients (NYHA class II-III) were classified as HFpEF (LVEF>=45%) or HFrEF (LVEF<45%). Results: One-hundred and eighty participants were categorized in four groups: athletes (n=44, 32±12 years), HFpEF (n=47, 61±11 years, H2FPEF score 5±2), HFrEF (n=47, 54±10 years), and healthy controls (n=42, 41±13 years). LVEF was markedly reduced in HFrEF (athletes 65±6%, HFpEF 59±11, HFrEF 29±9, controls 66±4, p<.001). LV mass index (athletes 65±6%, HFpEF 59±11, HFrEF 29±9, controls 66±4, p<.001) and cardiomyocyte mass index (athletes 64±15g/m 2 , HFpEF 66±24, HFrEF 82±36, controls 42±8, p<.001) were greater in athletes and in HF patients (Fig 1A). Athletes and HFpEF patients had concentric LV remodeling, while HFrEF patients showed eccentric remodeling (Fig 1B). Intracellular lifetime of water was longer in athletes and shorter in HFrEF (athletes .17±.07s, HFpEF .15±.05, HFrEF .13±.05, controls .14±.05, p<.001) (Fig 2A). ECV was similarly increased in both HF groups (athletes .28±.04%, HFpEF .31±.05, HFrEF .31±.05, controls .28±.04, p<.001) (Fig 2B). Native T1 (athletes 1175±55ms, HFpEF 1261±61, HFrEF 1274±61, controls 1229±75, p=.01) correlated with CPET maximal oxygen consumption (VO 2 max) in HF patients (r=-.023, p=.048) (athletes 52±10, HFpEF 18±6, HFrEF 17±4, controls 29±9, p<.001). Conclusion: Physiological hypertrophy was characterized by increased cardiomyocyte diameter, normal ECV, and shorter native T1 due to its greater cardiomyocyte volume. Contrastingly, pathological hypertrophy’s longer native T1 was a result of its higher ECV and correlated with VO 2 max in HF. Cardiomyocyte diameter was smaller in HFrEF than in HFpEF.

Abstract 11489: Pregnancy Increases Cardiac Vulnerability to Post-Partum Pathological Stimuli

Introduction: The hemodynamic demands on the heart during normal pregnancy induce physiological cardiac hypertrophy. Together with exercise induced cardiac hypertrophy and cardiac enlargement during post-natal growth, these physiological cardiac adaptations are distinct from pathological hypertrophy caused by heart diseases including volume/pressure overload. Exercise-induced cardiac hypertrophy can induce a protective phenotype that leads to resistance from ischemic injury or pressure overload induced pathological remodeling. Whether pregnancy induced cardiac hypertrophy can also protect the heart from post-partum (PP) pathological stimuli remains unknown and is the focus of this study. Methods: We challenged both post-partum and age matched non-pregnant female C57BL/6 mice with 7-day osmotic minipump infusion of Angiotensin II/phenylephrine (AngII/PE) and determined the cardiac alterations. Results: PP mice had more severe cardiac pathological remodeling after AngII/PE infusion compared with non-pregnant counterparts, with greater increases in heart weight, cardiomyocyte hypertrophy and fibrosis. Echocardiography showed both left and right ventricular hypertrophy without overt systolic dysfunction. PP mice had greater elevations in expression levels of fetal genes and fibrotic genes compared with non-pregnant mice after AngII/PE infusion. RNA-sequencing analysis suggested a more robust change in gene expression level in PP mice after AngII/PE treatment compared to non-pregnant counterparts, with a substantial role for extracellular matrix organization genes. We also found a significant alteration of gene expression levels for enriched extracellular structural organization at 1-day PP, which underlies ongoing structural re-organization in the myocardium shortly after deliver. These PP changes may predispose the heart to adverse remodeling when simultaneously challenged with pathological stimuli. Conclusions: Pregnancy induced cardiac remodeling does not protect the heart against PP pathological stimuli. In fact, the rapid remodeling in the PP heart may predispose it to exacerbation of pathological remodeling.

Angiotensin II-Induced Signal Transduction Mechanisms for Cardiac Hypertrophy.

Although acute exposure of the heart to angiotensin (Ang II) produces physiological cardiac hypertrophy and chronic exposure results in pathological hypertrophy, the signal transduction mechanisms for these effects are of complex nature. It is now evident that the hypertrophic response is mediated by the activation of Ang type 1 receptors (AT1R), whereas the activation of Ang type 2 receptors (AT2R) by Ang II and Mas receptors by Ang-(1-7) exerts antihypertrophic effects. Furthermore, AT1R-induced activation of phospholipase C for stimulating protein kinase C, influx of Ca2+ through sarcolemmal Ca2+- channels, release of Ca2+ from the sarcoplasmic reticulum, and activation of sarcolemmal NADPH oxidase 2 for altering cardiomyocytes redox status may be involved in physiological hypertrophy. On the other hand, reduction in the expression of AT2R and Mas receptors, the release of growth factors from fibroblasts for the occurrence of fibrosis, and the development of oxidative stress due to activation of mitochondria NADPH oxidase 4 as well as the depression of nuclear factor erythroid-2 activity for the occurrence of Ca2+-overload and activation of calcineurin may be involved in inducing pathological cardiac hypertrophy. These observations support the view that inhibition of AT1R or activation of AT2R and Mas receptors as well as depression of oxidative stress may prevent or reverse the Ang II-induced cardiac hypertrophy.

Perilipin Isoforms and PGC-1α Are Regulated Differentially in Rat Heart during Pregnancy-Induced Physiological Cardiac Hypertrophy.

Background and Objectives: Perilipins 1–5 (PLIN) are lipid droplet-associated proteins that participate in regulating lipid storage and metabolism, and the PLIN5 isoform is known to form a nuclear complex with peroxisome proliferator-activated receptor-gamma coactivator 1-alpha (PGC-1α) to regulate lipid metabolism gene expression. However, the changes in PLIN isoforms’ expression in response to pregnancy-induced cardiac hypertrophy are not thoroughly studied. The aim of this study was to quantify the mRNA expression of PLIN isoforms and PGC-1α along with total triacylglycerol (TAG) and cholesterol levels during late pregnancy and the postpartum period in the rat left ventricle. Materials and Methods: Female Sprague-Dawley rats were divided into three groups: non-pregnant, late pregnancy, and postpartum. The mRNA and protein levels were evaluated using quantitative RT-PCR and Western blotting, respectively. TAG and total cholesterol content were evaluated using commercial colorimetric methods. Results: The expression of mRNAs for PLIN1, 2, and 5 increased during pregnancy and the postpartum period. PGC-1α mRNA and protein expression increased during pregnancy and the postpartum period. Moreover, TAG and total cholesterol increased during pregnancy and returned to basal levels after pregnancy. Conclusions: Our results demonstrate that pregnancy upregulates differentially the expression of PLIN isoforms along with PGC-1α, suggesting that together they might be involved in the regulation of the lipid metabolic shift induced by pregnancy.

Multiparametric CMR tissue characterization differentiates pathological from physiological phenotypes

Abstract Background An abnormal increase of cardiomyocyte mass of the left ventricle is observed in physiological and pathological phenotypes of hypertrophy. Aims To apply CMR tissue characterization using native T1/T2 and post-contrast T1 mapping and identify tissue phenotypes corresponding to physiological and pathological hypertrophy, in athletes and heart failure (HF), respectively. Methods/Results 187 individuals were prospectively enrolled, in 4 groups: Athletes (n=56, 32±13 years), HF with and without preserved ejection fraction (HFpEF: n=49, 62±12 years; HFrEF: n=49, 54±16 years, H2FpEF-score: 4.8 [3–9]), and healthy controls (n=33, 41±13.7 years). All participants underwent cardiopulmonary exercise testing and a multiparametric CMR study to assess morphology/function, T2, native T1, extracellular volume fraction (ECV), and intracellular lifetime of water (a marker of cardiomyocyte diameter). As expected, LVEF varied significantly among groups (Athletes: 64.7±6.1%, HFpEF: 59.3±10.7%, HFrEF: 29.4±8.5%, and controls: 65.4±4.3%, p<0.001) and was markedly reduced in HFrEF. Both LV mass index (Athletes: 64.1±15.8 g/m2, HFpEF: 62.3±24 g/m2, HFrEF: 79.5±36.7 g/m2, and controls: 42±9.2 g/m2, p<0.001) and cardiomyocyte mass index (calculated as (1 − ECV) x LV mass/BSA) (Athletes: 47.9±13.1 g/m2, HFpEF: 42.2±17.2 g/m2, HFrEF: 55.69±24.70 g/m2, and controls: 30.7±6.9 g/m2, p<0.001, Fig. 1A) were elevated in athletes and HF, compared to controls. Athletes and HFpEF patients showed concentric LV remodeling, while the eccentric LV remodeling was observed in HFrEF (Fig. 1B). In the HF groups NT-proBNP was elevated (Athletes: 34.6±16.8 ng/dL, HFpEF: 473.2±700.1 ng/dL, HFrEF: 1,365.3±1,772 ng/dL, and controls: 34.3±29 ng/dL, p<0.005), and adjusted maximum oxygen consumption was markedly reduced (Athletes: 49.4±9.3 mL/kg/min, HFpEF: 18.3±5.5 mL/kg/min, HFrEF: 17.1±4.2 mL/kg/min, and controls: 30.3±10.2 mL/kg/min, p<0.005). ECV was larger in both HF groups (athletes: 0.27±0.04, HFpEF: 0.31±0.05, HFrEF: 0.32±0.04, and controls: 0.26±0.02, p<0.001). The intracellular lifetime of water was longer among athletes compared to controls and shorter in HFrEF compared to HFpEF (Athletes: 0.17±0.07, HFpEF: 0.15±0.05, HFrEF: 0.13±0.05, and controls: 0.14±0.05, p<0.001). Native T1 was reduced in athletes compared to controls and elevated in the HF groups (Athletes: 1,173.4±63.2 ms, HFpEF: 1,262.8±62.4 ms, HFrEF: 1,275.1±59.9 ms, and controls: 1,212.78±76.01 ms, p<0.001). Lastly, the an increased T2 was indicative of edema in HF patients (Fig. 2). Conclusions In a prospective observational study with CMR T1/T2 mapping, physiological hypertrophy is characterized by increased cardiomyocyte diameter, normal ECV, and a decrease in native T1, due to the larger cardiomyocyte volume. In contrast, with pathological hypertrophy in HF, is associated with an increased and an above-normal native T1. Cardiomyocyte diameter appears reduced in HFrEF compared to HFpEF, reflecting the transition to an eccentric LV shape. Funding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): The São Paulo Research Foundation

Proteomic analysis of exercise-induced hypertrophy reveals sex-related mitochondrial differences mediated by AMPK

Abstract Background Regular physical activity results in characteristic structural and functional changes in the heart, which are collectively referred to as the athlete's heart. However, the extent of exercise-induced left ventricular (LV) hypertrophy and functional changes show significant differences between men and women, the molecular background of which is not fully elucidated. Objective The aim of this study was to provide a proteomic characterization of long-term, intense exercise-induced LV myocardial hypertrophy in a rat model, with a focus on sex-related differences. Methods Our rats were divided into trained (FEx) and control female (FCo) as well as trained (MEx) and control male (MCo) groups. In the trained groups, athlete's heart was induced by a 12-week swimming protocol. Myocardial hypertrophy was confirmed by echocardiography and functional adaptation by pressure-volume analysis. Proteomic measurements based on liquid chromatograph-coupled mass spectrometry were performed on proteins isolated from our LV myocardial samples. Results Echocardiography and post-mortem myocardial mass showed significant LV hypertrophy in both sexes, which was more pronounced in female animals (tibial length normalized LV muscle mass: + 17.4% MEx vs. MCo, + 31.0% FEx vs. FCo). LV contractility increased to the same extent in both sexes. Relative expression of 3074 proteins were determined by proteomics. There was a significant change in expression of 229 proteins in males and 599 in females compared to the level of same-sex controls. Based on our gene ontological analysis, physiological LV remodeling in females is characterized by increased expression of proteins in mitochondrial function (cellular respiration and fatty acid oxidation) and biogenesis, whereas in males, proteins that bind to the actin cytoskeleton is primarily increased. Further investigation revealed that the quantity of AMP-activated protein kinase (AMPK) and sirtuin 3 (SIRT3) was increased only in female animals. Conclusions Our data suggests that physiological LV hypertrophy resulting from regular, balanced exercise is associated with sex-specific changes in the myocardial proteome. The main differences might be associated with different regulation of mitochondrial function and biogenesis, related to AMPK pathway. Our results contribute to the understanding of the development of physiological myocardial hypertrophy. Funding Acknowledgement Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Bolyai János Research Scholarship (BO/00837/21) to OANational Research, Development and Innovation Office (NKFIH) K135076 to B.M.

Spermidine overrides INSR (insulin receptor)-IGF1R (insulin-like growth factor 1 receptor)-mediated inhibition of autophagy in the aging heart

ABSTRACT Although attenuated IGF1R (insulin-like growth factor 1 receptor) signaling has long been viewed to promote longevity in model organisms, adverse effects on the heart have been the subject of major concern. We observed that IGF1R is overexpressed in cardiac tissues from patients with end-stage non-ischemic heart failure, coupled to the activation of the IGF1R downstream effector AKT/protein kinase B and inhibition of ULK1 (unc-51 like autophagy activating kinase 1). Transgenic overexpression of human IGF1R in cardiomyocytes from mice initially induces physiological cardiac hypertrophy and superior function, but later in life confers a negative impact on cardiac health, causing macroautophagy/autophagy inhibition as well as impaired oxidative phosphorylation, thus reducing life expectancy. Treatment with the autophagy inducer and caloric restriction mimetic spermidine ameliorates most of these IGF1R-induced cardiotoxic effects in vivo. Moreover, inhibition of IGF1R signaling by means of a dominant-negative phosphoinositide 3-kinase (PI3K) mutant induces cardioprotective autophagy, restores myocardial bioenergetics and improves late-life survival. Hence, our results demonstrate that IGF1R exerts a dual biphasic impact on cardiac health, and that autophagy mediates the late-life geroprotective effects of IGF1R inhibition in the heart.

Potential Role of Exercise in Regulating YAP and TAZ During Cardiomyocytes Aging.

Adaptation of cardiac muscle to regular exercise results in morphological and structural changes known as physiological cardiac hypertrophy, to which the Hippo signaling pathway might have contributed. Two major terminal effectors in the Hippo signaling pathway are Yes-associated protein (YAP) and its homolog transcriptional coactivator with PDZ-binding motif (TAZ). The latest studies have reported the role of YAP and TAZ in different life stages, such as in fetal, neonatal, and adult hearts. Their regulation might involve several mechanisms and effectors. One of the possible coregulators is exercise. Exercise plays a role in cardiomyocyte hypertrophic changes during different stages of life, including in aged hearts. YAP/TAZ signaling pathway has a role in physiological cardiac hypertrophy induced by exercise and is associated with cardiac remodelling. Thus, it can be believed that exercise has roles in activating the signaling pathway of YAP and TAZ in aged cardiomyocytes. However, the studies regarding the roles of YAP and TAZ during cardiomyocyte aging are limited. The primary purpose of this review is to explore the response of cardiovascular aging to exercise via signaling pathway of YAP and TAZ.

Abstract P2007: Bmal1 Drives Postnatal Cardiac Hypertrophy Via Circadian Chromatin Remodeling Of The Pro-hypertrophic Gene Sik1

Background: During neonatal cardiac development, myocytes integrate cues such as changes in blood pressure and circulating hormones to execute a temporal genetic response that drives physiological cardiac hypertrophy. Chromatin remodeling precedes the adult heart’s response to growth stimuli, yet the temporal nature of neonatal chromatin remodeling is unclear. In other tissues, genes regulated by the master circadian rhythm factor BMAL1 display circadian oscillations in histone acetylation and nucleosome and RNAP II occupancy. We hypothesized that BMAL1 regulates temporal chromatin remodeling and expression of genes critical for neonatal cardiac hypertrophy. Methods: BMAL1 chromatin immunoprecipitation sequencing (ChIP-Seq) and assay for transposase-accessible chromatin and sequencing (ATAC-Seq) data from murine hearts were analyzed to identify genes at which BMAL1 may drive chromatin remodeling. To interrogate myocyte time-of-day dependent response to growth stimuli, neonatal rat ventricular myocytes (NRVM) were subjected to serum shock synchronization to drive oscillatory BMAL1 expression, followed by treatment with the growth stimulus phenylephrine (PE) at the peak and trough of BMAL1 expression. BMAL1 was knocked down via siRNA and hypertrophy was assessed by measurement of cell size and of RT-PCR of fetal genes (Nppa and Nppb). Results: BMAL1 ChIP-Seq data revealed myocyte-specific BMAL1 localization to regions exhibiting an open chromatin signature based on ATAC-seq, including the pro-hypertrophic gene salt-inducible kinase 1 ( Sik1 ). Serum shock induced oscillations of BMAL1 and histone H3.3: administration of PE at the peak of BMAL1 expression induced a 30% increase in cell size and 2-fold increase in fetal gene expression. PE given at the trough of BMAL1 expression affected neither cell size nor fetal genes, demonstrating a critical role for the circadian clock in myocyte growth. BMAL1 knockdown: decreased expression of its known target and partner clock gene, Per2 , as well as expression of Sik1, Nppa , and Nppb ; decreased myocyte size by 30%; and increased expression of histone H3.3. Conclusions: These data indicate that BMAL1 temporally regulates myocyte growth by modulating histone stoichiometry and expression of Sik1 .

Myocardial Work Efficiency in Physiologic Left Ventricular Hypertrophy of Power Athletes

The athlete's heart in power training is characterized by physiologic concentric remodeling. Our aim was to analyze left ventricular (LV) myocardial deformation and contractile reserve (CR) in top-level power athletes (PA) at rest and during exercise and their possible correlations with functional capacity. Standard echo, lung ultrasound, and LV 2D speckle-tracking strain were performed at rest and during exercise in PA and in age- and sex-comparable healthy controls. 250 PA (male: 62%; 33.6 ± 4.8 years) and 180 age- and sex-comparable healthy controls were enrolled. LV ejection fraction (EF) at baseline was comparable between the two groups, while LV global longitudinal strain (GLS) was reduced in PA (GLS: -17.8 ± 2.4 in PA vs. -21.9 ± 3.8 in controls; P < 0.01). Conversely, myocardial work efficiency (MWE) did not show significant difference between the two groups (94.4 ± 3.2 in PA vs. 95.9 ± 4.6% in controls; P NS). At peak exertion during exercise stress echocardiography (ESE), PA showed better exercise capacity and peak VO2 consumption (51.6 ± 10.2 in EA vs. 39.8 ± 8.2 mL/Kg/min in controls, P < 0.0001), associated with augmented pulmonary artery systolic pressure (PASP). By multivariable analysis, MWE at rest was the most predictive factor of maximal watts (P < 0.0001), peak VO2, (P < 0.0001), PASP (P < 0.001), and number of B-lines (P < 0.001), all measured at peak effort. In power athletes, MWE showed less load dependency than GLS. Normal resting values of MWE in PA suggest a physiological LV remodeling, associated with a better exercise capacity and preserved CR during physical stress.

Comparison of ANP and BNP Granular Density in Atria of Rats After Physiological and Pathological Hypertrophy.

Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) are cardiac hormones located in atria granules. Both peptides respond to cardiac pressure and volume dynamics and accordingly serve as translation biomarkers for the clinical treatment of heart failure. Serum ANP and BNP play central secretary roles in blood pressure and cardiac output regulation and have proven utility as differential biomarkers of cardiovascular proficiency and drug-induced maladaptation, yet both peptides are impervious to exercise-induced hypertrophy. We employed immunoelectron microscopy to examine the effects of 28 days of chronic swim exercise or administration of a PPARγ agonist on atrial granules and their stored natriuretic peptides in Sprague Dawley rats. Chronic swimming and drug treatment both resulted in a 15% increase in heart weight compared with controls, with no treatment effects on perinuclear granule area in the left atria (LAs). Drug treatment resulted in larger size granules with greater BNP density in the right atria. Comparing swimming and PPARγ agonist treatment effects on ANP:BNP granule density ratios between atrial chambers revealed a shift toward a greater proportion of ANP than BNP in LAs of swim-trained rats. These data suggest a distinction in the population of ANP and BNP after chronic swim or PPARγ that makes it a novel metric for the differentiation of pathological and physiological hypertrophy.

Global longitudinal strain differentiates physiological hypertrophy from maladaptive remodeling.

AimsDifferentiation of left ventricular (LV) hypertrophy in healthy athletes from pathological LV hypertrophy in heart disease is often difficult. We explored whether extended echocardiographic measurements such as E/e’ and global longitudinal strain (GLS) distinguish physiologic from maladaptive hypertrophy in hypertrophic cardiomyopathy, excessively trained athletes’ hearts and normal hearts.MethodsSeventy-eight professional athletes (cyclists n = 37, soccer players n = 29, handball players n = 21) were compared with patients (n = 88) with pathological LV hypertrophy (hypertrophic obstructive cardiomyopathy (HOCM, n = 17), hypertensive heart disease (HHD, n = 36), severe aortic valve stenosis (AVS, n = 35) and with sedentary healthy individuals as controls (n = 37).ResultsLV ejection fraction (LVEF) was ≥50% in all patients, athletes (median age 26 years, all male) and the controls (97% male, median age 32 years). LV mass index (LVMI) and septal wall thickness was in normal range in controls, but elevated in cyclists and patients with pathological hypertrophy (p < 0.001 for both). E/e’ was elevated in all patients with maladaptive hypertrophy but normal in controls and athletes (p < 0.001 vs. pathological hypertrophy). Furthermore GLS was reduced in patients with pathological hypertrophy compared with athletes and controls (for both p < 0.001). In subjects with septal wall thickness >11 mm, GLS (≥−18%) has a specificity of 79% to distinguish between physiological and pathological hypertrophy.ConclusionGLS and E/e’ are reliable parameters unlike left ventricular mass or LV ejection fraction to distinguish pathological and physiological hypertrophy.

Pregnancy‐induced physiological cardiac hypertrophy regulates the expression of perilipin isoforms

Perilipins (PLINs) isoforms are proteins associated to surface of intracelular lipid droplets (LDs) that participate in the regulation of lipid metabolism and storage during hypertrophic cardiomyopathies. PLINs can associate to the PPAR coactivators peroxisome proliferator‐activated receptor gamma coactivator 1‐alpha (PGC‐1α) and Sirtuin 1 (SIRT1) to regulate the expression of genes involved in lipid metabolism. Pregnancy‐induced physiological cardiac hypertrophy is a reversible process in which there is a change in lipid metabolism. However, there are a lack attention of the participation of PLINs isoforms in response to pregnancy‐induced cardiac hypertrophy. In this work, we quantified the PLINs isoforms and PGC‐1α mRNAs and proteins level, along with the transcriptional activities de PPARs family, triacylglyceride (TAG) and cholesterol/ester cholesterol in left ventricle of rats before, during, and after pregnancy. Expressions of mRNAs for PLIN1, PLIN2 and PLIN5 increased 9.5‐ and 7.4‐fold, 27.5‐ and 17.7‐fold, and 8‐ and 2.4‐fold 2 during pregnancy and postpartum, respectively, while PLIN3 did not change and PLIN4 was not detected. In contrast, the protein content of PLIN2 increased 1.5‐fold during postpartum, and PLIN5 increased 1.3‐ and 1.5‐ fold during pregnancy and postpartum, respectively, while PLIN1 did not change. Expression of mRNA and protein content for PGC‐1α increased 17.7 and 11.26‐fold and 1.5‐ and 1.2‐ fold during pregnancy and postpartum, respectively. The activity of PPARγ increased 1.6‐fold during pregnancy and decreased to basal levels postpartum. The concentration of TAG and Cholesterol/Cholesteryl ester increased 1.5‐ and 1.4‐ fold in the pregnant group compared to the non‐pregnant group, and returned to basal levels at postpartum, respectively. The results demonstrate that pregnancy‐induced, physiological cardiac hypertrophy activates the expression of genes involved in lipid storage suggesting that the shift in cardiac metabolism is mediated by the activation of PPARγ/PGC‐1α.

Lymphangiogenesis contributes to exercise-induced physiological cardiac growth

BackgroundPromoting cardiac lymphangiogenesis exerts beneficial effects for the heart. Exercise can induce physiological cardiac growth with cardiomyocyte hypertrophy and increased proliferation markers in cardiomyocytes. However, it remains unclear whether and how lymphangiogenesis contributes to exercise-induced physiological cardiac growth. We aimed to investigate the role and mechanism of lymphangiogenesis in exercise-induced physiological cardiac growth. MethodsAdult C57BL6/J mice were subjected to 3 weeks of swimming exercise to induce physiological cardiac growth. Oral treatment with vascular endothelial growth factor receptor 3 (VEGFR3) inhibitor SAR131675 was used to investigate whether cardiac lymphangiogenesis was required for exercise-induced physiological cardiac growth by VEGFR3 activation. Furthermore, human dermal lymphatic endothelial cell (LEC)-conditioned medium was collected to culture isolated neonatal rat cardiomyocytes to determine whether and how LECs could influence cardiomyocyte proliferation and hypertrophy. ResultsSwimming exercise induced physiological cardiac growth accompanied by a remarkable increase of cardiac lymphangiogenesis as evidenced by increased density of lymphatic vessel endothelial hyaluronic acid receptor 1–positive lymphatic vessels in the heart and upregulated LYVE-1 and Podoplanin expressions levels. VEGFR3 was upregulated in the exercised heart, while VEGFR3 inhibitor SAR131675 attenuated exercise-induced physiological cardiac growth as evidenced by blunted myocardial hypertrophy and reduced proliferation marker Ki67 in cardiomyocytes, which was correlated with reduced lymphatic vessel density and downregulated LYVE-1 and Podoplanin in the heart upon exercise. Furthermore, LEC-conditioned medium promoted both hypertrophy and proliferation of cardiomyocytes and contained higher levels of insulin-like growth factor-1 and the extracellular protein Reelin, while LEC-conditioned medium from LECs treated with SAR131675 blocked these effects. Functional rescue assays further demonstrated that protein kinase B (AKT) activation, as well as reduced CCAAT enhancer-binding protein beta (C/EBPβ) and increased CBP/p300-interacting transactivators with E (glutamic acid)/D (aspartic acid)–rich-carboxylterminal domain 4 (CITED4), contributed to the promotive effect of LEC-conditioned medium on cardiomyocyte hypertrophy and proliferation. ConclusionOur findings reveal that cardiac lymphangiogenesis is required for exercise-induced physiological cardiac growth by VEGFR3 activation, and they indicate that LEC-conditioned medium promotes both physiological hypertrophy and proliferation of cardiomyocytes through AKT activation and the C/EBPβ-CITED4 axis. These results highlight the essential roles of cardiac lymphangiogenesis in exercise-induced physiological cardiac growth.

Diferenciální diagnostika zvětšení hypofýzy

Enlargement of the pituitary gland is heterogenous in the etiology. Common causes of pituitary enlargement are physiological hypertrophy during pregnancy, primary and secondary tumors, autoimmune hypophysitis including side effects of anticancer therapy with check-point inhibitors. Terms like hypertrophy, hyperplasia, sellar expansion and hypophysitis are commonly used to describe enlargement of the pituitary gland on MR scan regardless its etiology. The most common pathology causing pituitary gland enlargement is pituitary adenoma. Magnetic resonance imaging can differentiate pituitary tumors from diffuse enlargement due to hypophysitis in most but not all cases. Changes on imaging during time or response to pharmacotherapy might help determine the final diagnosis in uncertain cases. We present a case report of a young woman with sellar expansion due to prolonged untreated peripheral hypothyroidism mimicking pituitary adenoma. Interdisciplinary cooperation of endocrinologist, radiologist and neurosurgeon is crucial in determining the diagnosis.