Travelling with heart failure: risk assessment and practical recommendations.

Patients with heart failure are at a higher risk of cardiovascular events compared with the general population, particularly during domestic or international travel. Patients with heart failure should adhere to specific recommendations during travel to lower their risk of developing heart failure symptoms. In this Review, we aim to provide clinicians with a set of guidelines for patients with heart failure embarking on national or international travel. Considerations when choosing a travel destination include travel distance and time, the season upon arrival, air pollution levels, jet lag and altitude level because all these factors can increase the risk of symptom development in patients with heart failure. In particular, volume depletion is of major concern while travelling given that it can contribute to worsening heart failure symptoms. Pre-travel risk assessment should be performed by a clinician 4-6 weeks before departure, and patients should receive advice on potential travel-related illness and on strategies to prevent volume depletion. Oxygen supplementation might be useful for patients who are very symptomatic. Upon arrival at the destination, potential drug-induced photosensitivity (particularly in tropical destinations) and risks associated with the local cuisine require consideration. Special recommendations are needed for patients with cardiac implantable electronic devices or left ventricular assist devices as well as for those who have undergone major cardiac surgery.

Age-related decline in murine heart and skeletal muscle performance is attenuated by reduced Ahnak1 expression.

BACKGROUND: Aging is associated with a progressive reduction in cellular function leading to poor health and loss of physical performance. Mitochondrial dysfunction is one of the hallmarks of aging; hence, interventions targeting mitochondrial dysfunction have the potential to provide preventive and therapeutic benefits to elderly individuals. Meta-analyses of age-related gene expression profiles showed that the expression of Ahnak1, a protein regulating several signal-transduction pathways including metabolic homeostasis, is increased with age, which is associated with low VO2MAX and poor muscle fitness. However, the role of Ahnak1 in the aging process remained unknown. Here, we investigated the age-related role of Ahnak1 in murine exercise capacity, mitochondrial function, and contractile function of cardiac and skeletal muscles. METHODS: We employed 15- to 16-month-old female and male Ahnak1-knockout (Ahnak1-KO) and wild-type (WT) mice and performed morphometric, biochemical, and bioenergetics assays to evaluate the effects of Ahnak1 on exercise capacity and mitochondrial morphology and function in cardiomyocytes and tibialis anterior (TA) muscle. A human left ventricular (LV) cardiomyocyte cell line (AC16) was used to investigate the direct role of Ahnak1 in cardiomyocytes. RESULTS: We found that the level of Ahnak1 protein is significantly up-regulated with age in the murine LV (1.9-fold) and TA (1.8-fold) tissues. The suppression of Ahnak1 was associated with improved exercise tolerance, as all aged adult Ahnak1-KO mice (100%) successfully completed the running programme, whereas approximately 31% male and 8% female WT mice could maintain the required running speed and distance. Transmission electron microscopic studies showed that LV and TA tissue specimens of aged adult Ahnak1-KO of both sexes have significantly more enlarged/elongated mitochondria and less small mitochondria compared with WT littermates (P < 0.01 and P < 0.001, respectively) at basal level. Further, we observed a shift in mitochondrial fission/fusion balance towards fusion in cardiomyocytes and TA muscle from aged adult Ahnak1-KO mice. The maximal and reserve respiratory capacities were significantly higher in cardiomyocytes from aged adult Ahnak1-KO mice compared with the WT counterparts (P < 0.05 and P < 0.01, respectively). Cardiomyocyte contractility and fatigue resistance of TA muscles were significantly increased in Ahnak1-KO mice of both sexes, compared with the WT groups. In vitro studies using AC16 cells have confirmed that the alteration of mitochondrial function is indeed a direct effect of Ahnak1. Finally, we presented Ahnak1 as a novel cardiac mitochondrial membrane-associated protein. CONCLUSIONS: Our data suggest that Ahnak1 is involved in age-related cardiac and skeletal muscle dysfunction and could therefore serve as a promising therapeutical target.

Selective androgen receptor modulators (SARMs) as pharmacological treatment for muscle wasting in ongoing clinical trials.

INTRODUCTION: Skeletal muscle wasting is a frequent clinical problem encountered in patients with chronic diseases. Increased levels of inflammatory markers play a role in the imbalance between muscle protein synthesis and degradation. Although testosterone has long been proposed as a treatment for patients with muscle wasting, undesirable side effects have raised concerns about prostatic hypertrophy in men as well as virilization in women. Selective androgen receptor modulators (SARMs) have demonstrated similar results like testosterone at improving lean body mass (LBM) with less side effects on androgen-dependent tissue. AREAS COVERED: This review outlines the ongoing clinical development in the field of SARMs and their effectiveness in improving body composition and physical function. The included articles were collected at pubmed.gov and analyzed integrally. EXPERT OPINION: There is an unmet clinical need for safe and effective anabolic compounds such as SARMs. Despite the effect on LBM shown by SARMs in phase II clinical trials, results on improved physical function and muscle strength are still lacking and long-term outcomes have to be assessed in these patients. Moreover, there is a need to determine the effect of resistance exercise training and protein intake associated with SARMs in the treatment of patients with muscle wasting.

The Role of 17ß-Estradiol and Estrogen Receptors in Regulation of Ca2+ Channels and Mitochondrial Function in Cardiomyocytes.

Numerous epidemiological, clinical, and animal studies showed that cardiac function and manifestation of cardiovascular diseases (CVDs) are different between males and females. The underlying reasons for these sex differences are definitely multifactorial, but major evidence points to a causal role of the sex steroid hormone 17ß-estradiol (E2) and its receptors (ER) in the physiology and pathophysiology of the heart. Interestingly, it has been shown that cardiac calcium (Ca2+) ion channels and mitochondrial function are regulated in a sex-specific manner. Accurate mitochondrial function and Ca2+ signaling are of utmost importance for adequate heart function and crucial to maintaining the cardiovascular health. Due to the highly sensitive nature of these processes in the heart, this review article highlights the current knowledge regarding sex dimorphisms in the heart implicating the importance of E2 and ERs in the regulation of cardiac mitochondrial function and Ca2+ ion channels, thus the contractility. In particular, we provide an overview of in-vitro and in-vivo studies using either E2 deficiency; ER deficiency or selective ER activation, which suggest that E2 and ERs are strongly involved in these processes. In this context, this review also discusses the divergent E2-responses resulting from the activation of different ER subtypes in these processes. Detailed understanding of the E2 and ER-mediated molecular and cellular mechanisms in the heart under physiological and pathological conditions may help to design more specifically targeted drugs for the management of CVDs in men and women.

Ninjurin1 regulates striated muscle growth and differentiation.

Chronic pressure overload due to aortic valve stenosis leads to pathological cardiac hypertrophy and heart failure. Hypertrophy is accompanied by an increase in myocyte surface area, which requires a proportional increase in the number of cell-cell and cell-matrix contacts to withstand enhanced workload. In a proteomic analysis we identified nerve injury-induced protein 1 (Ninjurin1), a 16kDa transmembrane cell-surface protein involved in cell adhesion and nerve repair, to be increased in hypertrophic hearts from patients with aortic stenosis. We hypothesised that Ninjurin1 is involved in myocyte hypertrophy. We analyzed cardiac biopsies from aortic-stenosis patients and control patients undergoing elective heart surgery. We studied cardiac hypertrophy in mice after transverse aortic constriction and angiotensin II infusions, and performed mechanistic analyses in cultured myocytes. We assessed the physiological role of ninjurin1 in zebrafish during heart and skeletal muscle development. Ninjurin1 was increased in hearts of aortic stenosis patients, compared to controls, as well as in hearts from mice with cardiac hypertrophy. Besides the 16kDa Ninjurin1 (Ninjurin1-16) we detected a 24kDa variant of Ninjurin1 (Ninjurin1-24), which was predominantly expressed during myocyte hypertrophy. We disclosed that the higher molecular weight of Ninjurin1-24 was caused by N-glycosylation. Ninjurin1-16 was contained in the cytoplasm of myocytes where it colocalized with stress-fibers. In contrast, Ninjurin1-24 was localized at myocyte membranes. Gain and loss-of-function experiments showed that Ninjurin1-24 plays a role in myocyte hypertrophy and myogenic differentiation in vitro. Reduced levels of ninjurin1 impaired cardiac and skeletal muscle development in zebrafish. We conclude that Ninjurin1 contributes to myocyte growth and differentiation, and that these effects are mainly mediated by N-glycosylated Ninjurin1-24.

Sex-specific regulation of collagen I and III expression by 17ß-Estradiol in cardiac fibroblasts: role of estrogen receptors.

Aims: Sex differences in cardiac fibrosis point to the regulatory role of 17ß-Estradiol (E2) in cardiac fibroblasts (CF). We, therefore, asked whether male and female CF in rodent and human models are differentially susceptible to E2, and whether this is related to sex-specific activation of estrogen receptor alpha (ERα) and beta (ERß). Methods and results: In female rat CF (rCF), 24 h E2-treatment (10-8 M) led to a significant down-regulation of collagen I and III expression, whereas both collagens were up-regulated in male rCF. E2-induced sex-specific collagen regulation was also detected in human CF, indicating that this regulation is conserved across species. Using specific ERα- and ERß-agonists (10-7 M) for 24 h, we identified ERα as repressive and ERß as inducing factor in female and male rCF, respectively. In addition, E2-induced ERα phosphorylation at Ser118 only in female rCF, whereas Ser105 phosphorylation of ERß was exclusively found in male rCF. Further, in female rCF we found both ER bound to the collagen I and III promoters using chromatin immunoprecipitation assays. In contrast, in male rCF only ERß bound to both promoters. In engineered connective tissues (ECT) from rCF, collagen I and III mRNA were down-regulated in female ECT and up-regulated in male ECT by E2. This was accompanied by an impaired condensation of female ECT, whereas male ECT showed an increased condensation and stiffness upon E2-treatment, analysed by rheological measurements. Finally, we confirmed the E2-effect on both collagens in an in vivo mouse model with ovariectomy for E2 depletion, E2 substitution, and pressure overload by transverse aortic constriction. Conclusion: The mechanism underlying the sex-specific regulation of collagen I and III in the heart appears to involve E2-mediated differential ERα and ERß signaling in CFs.

Targeted basic research to highlight the role of estrogen and estrogen receptors in the cardiovascular system.

Epidemiological, clinical and animal studies revealed that sex differences exist in the manifestation and outcome of cardiovascular disease (CVD). The underlying molecular mechanisms implicated in these sex differences are not fully understood. The reasons for sex differences in CVD are definitely multifactorial, but major evidence points to the contribution of sex steroid hormone, 17ß-estradiol (E2), and its receptors, estrogen receptor alpha (ERα) and estrogen receptor beta (ERß). In this review, we summarize past and present studies that implicate E2 and ER as important determinants of sexual dimorphism in the physiology and pathophysiology of the heart. In particular, we give an overview of studies aimed to reveal the role of E2 and ER in the physiology of the observed sex differences in CVD using ER knock-out mice. Finally, we discuss recent findings from novel transgenic mouse models, which have provided new information on the sexual dimorphic roles of ER specifically in cardiomyocytes under pathological conditions.

17ß-Estradiol-induced interaction of estrogen receptor α and human atrial essential myosin light chain modulates cardiac contractile function.

Chronic increased workload of the human heart causes ventricular hypertrophy, re-expression of the atrial essential myosin light chain (hALC-1), and improved contractile function. Although hALC-1 is an important positive inotropic regulator of the human heart, little is known about its regulation. Therefore, we investigated the role of the sex hormone 17ß-estradiol (E2) on hALC-1 gene expression, the underlying molecular mechanisms, and the impact of this regulatory process on cardiac contractile function. We showed that E2 attenuated hALC-1 expression in human atrial tissues of both sexes and in human ventricular AC16 cells. E2 induced the nuclear translocation of estrogen receptor alpha (ERα) and hALC-1 in AC16 cells, where they cooperatively regulate the transcriptional activity of hALC-1 gene promoter. E2-activated ERα required the estrogen response element (ERE) motif within the hALC-1 gene promoter to reduce its transcriptional activity (vehicle: 15.55 ± 4.80 vs. E2: 6.51 ± 3.69; ~2 fold). This inhibitory effect was potentiated in the presence of hALC-1 (vehicle: 11.13 ± 3.66 vs. E2: 2.18 ± 1.10; ~5 fold), and thus, hALC-1 acts as a co-repressor of ERα-mediated transcription. Yeast two-hybrid screening of a human heart cDNA library revealed that ERα interacts physically with hALC-1 in the presence of E2. This interaction was confirmed by Co-Immunoprecipitation and immunofluorescence in human atrium. As a further novel effect, we showed that chronic E2-treatment of adult mouse cardiomyocytes overexpressing hALC-1 resulted in reduced cell-shortening amplitude and twitching kinetics of these cells independent of Ca2+ activation levels. Together, our data showed that the expression of hALC-1 gene is, at least partly, regulated by E2/ERα, while hALC-1 acts as a co-repressor. The inotropic effect of hALC-1 overexpression in cardiomyocytes can be significantly repressed by E2.

Reduction of apoptosis and preservation of mitochondrial integrity under ischemia/reperfusion injury is mediated by estrogen receptor ß.

BACKGROUND: Estrogen improves cardiac recovery after ischemia/reperfusion (I/R) by yet incompletely understood mechanisms. Mitochondria play a crucial role in I/R injury through cytochrome c-dependent apoptosis activation. We tested the hypothesis that 17ß-estradiol (E2) as well as a specific ERß agonist improve cardiac recovery through estrogen receptor (ER)ß-mediated mechanisms by reducing mitochondria-induced apoptosis and preserving mitochondrial integrity. METHODS: We randomized ovariectomized C57BL/6N mice 24h before I/R to pre-treatment with E2 or a specific ERß agonist (ERßA). Isolated hearts were perfused for 20min prior to 30min global ischemia followed by 40min reperfusion. RESULTS: Compared with controls, ERßA and E2 treated groups showed a significant improvement in cardiac recovery, i.e. an increase in left ventricular developed pressure, dP/dtmax and dP/dtmin. ERßA and E2 pre-treatment led to a significant reduction in apoptosis with decreased cytochrome c release from the mitochondria and increased mitochondrial levels of anti-apoptotic Bcl2 and ACAA2. Protein levels of mitochondrial translocase inner membrane (TIM23) and mitochondrial complex I of respiratory chain were increased by ERßA and E2 pre-treatment. Furthermore, we found a significant increase of myosin light chain 2 (MLC2) phosphorylation together with ERK1/2 activation in E2, but not in ERßA treated groups. CONCLUSIONS: Activation of ERß is essential for the improvement of cardiac recovery after I/R through the inhibition of apoptosis and preservation of mitochondrial integrity and can be a achieved by a specific ERß agonist. Furthermore, E2 modulates MLC2 activation after I/R independent of ERß.

Cardiomyocyte-specific overexpression of oestrogen receptor ß improves survival and cardiac function after myocardial infarction in female and male mice.

ERß (oestrogen receptor ß) activation has been shown to be cardioprotective, but the cell types and mechanisms involved are not understood. To investigate whether ERß restricted to cardiomyocytes contributes to the observed cardioprotection, we tested the effects of cardiomyocyte-specific ERß-OE (ERß overexpression) on survival, cardiac remodelling and function after MI (myocardial infarction) and studied the molecular pathways potentially involved. Female and male mice with cardiomyocyte-specific ERß-OE and WT (wild-type) littermates were subjected to chronic anterior coronary artery ligation or sham surgery. Two weeks after MI, ERß-OE mice showed improved survival (100% and 83% compared with 76% and 58% in WT females and males respectively). ERß-OE was associated with attenuated LV (left ventricular) dilatation, smaller increase in heart weight, less lung congestion at similar MI size, and improved systolic and diastolic function in both sexes. We identified two potential pathways for ERß-mediated myocardial protection. First, male and female ERß-OE mice had a lower reduction of SERCA2a (sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase 2a) expression after MI, suggesting less reduction in diastolic Ca(2+)-reuptake into the sarcoplasmic reticulum post-MI. Secondly, male ERß-OE revealed attenuated cardiac fibrosis in the remote LV tissue and expression of fibrosis markers collagen I and III, periostin and miR-21. Cardiomyocyte-specific ERß-OE improved survival associated with reduced maladaptive remodelling, improved cardiac function and less heart failure development after MI in both sexes. These effects seem to be related, at least in part, to a better maintenance of Ca(2+) cycling in both sexes and a lower induction of cardiac fibrosis in males after MI.

Sex-dependent regulation of fibrosis and inflammation in human left ventricular remodelling under pressure overload.

AIMS: Women with aortic stenosis develop a more concentric form of LV hypertrophy than men. However, the molecular factors underlying sex differences in LV remodelling are incompletely understood. We took an unbiased approach to identify sex-specific patterns in gene expression and pathway regulation, and confirmed the most prominent findings in human hearts. METHODS AND RESULTS: Echocardiography was performed in 104 patients (53.8% women) with aortic stenosis before aortic valve replacement. LV mass, LV end-diastolic diameter, and relative wall thickness were included in a factor analysis to generate an index classifying LV remodelling as adaptive or maladaptive. Maladaptive remodelling was present in 64.6% of male and in 32.7% of female patients (P < 0.01). Genome-wide expression profiling of LV samples was performed in a representative subgroup of 19 patients (52.6% women) compared with samples from healthy controls (n = 18). Transcriptome characterization revealed that fibrosis-related genes/pathways were induced in male overloaded ventricles, while extracellular matrix-related and inflammatory genes/pathways were repressed in female overloaded ventricles (adjusted P < 0.05). We confirmed gene regulation by quantitative real-time reverse transcription-polymerase chain reaction and immunoblotting analysis, and we further demonstrate the relevance of our findings by histological documentation of higher fibrosis in men than in women. CONCLUSION: We conclude that in pressure overload distinct molecular processes are regulated between men and women. Maladaptive LV remodelling occurs more frequently in men and is associated with greater activation of profibrotic and inflammatory markers. Collectively, sex-specific regulation of these processes may contribute to sex differences in the progression to heart failure.

Maladaptive remodeling is associated with impaired survival in women but not in men after aortic valve replacement.

OBJECTIVES: The purpose of this study was to test whether adaptive or maladaptive remodeling is associated with survival in women and men after aortic valve replacement (AVR). BACKGROUND: Women with isolated aortic valve stenosis (AS) develop more concentric left ventricular hypertrophy (LVH) than men in similar disease states. We recently reported less up-regulation of profibrotic genes at AVR and faster LVH regression post-operatively in women than in men, suggesting that there are sex differences in the adaptation to pressure overload and its regression. METHODS: The study cohort included 128 patients (age 70.0 ± 9.6 years, 49% women) undergoing AVR for AS. Echocardiography was obtained before and 4.0 ± 1.6 years after surgery. Factor analysis was used to classify LVH as adaptive (combining smaller left ventricular [LV] mass/diameters and greater relative wall thicknesses) or maladaptive. Myocardial tissue samples from the LV septum were obtained during AVR to analyze cardiac fibrosis and associated key molecular regulators. RESULTS: Before AVR, LVH was classified as adaptive in 62% of women and 45% of men (p < 0.050). Four years after AVR, adaptive LVH was observed in 75% of women and 49% of men (p < 0.031). At surgery, more cardiac fibrosis was present in men compared with women (p < 0.05). Higher levels of transforming growth factor beta 1 (p < 0.01), SMAD2 phosphorylation (p < 0.001), and periostin expression (p < 0.05) were found in men than in women. Women with maladaptive LVH had worse survival than women with adaptive LVH (p < 0.050), whereas the pattern of LVH did not affect survival in men (p < 0.307). CONCLUSIONS: Women more frequently exhibit adaptive LV remodeling with less fibrosis than men. Maladaptive LVH is associated with worse survival in women. Thus, sex should be considered as a strong modulating factor when management of patients with AS is discussed.

Cardiomyocyte-specific Estrogen Receptor Alpha Increases Angiogenesis, Lymphangiogenesis and Reduces Fibrosis in the Female Mouse Heart Post-Myocardial Infarction.

Experimental studies showed that 17ß-estradiol (E2) and activated Estrogen Receptors (ER) protect the heart from ischemic injury. However, the underlying molecular mechanisms are not well understood. To investigate the role of ER-alpha (ERα) in cardiomyocytes in the setting of myocardial ischemia, we generated transgenic mice with cardiomyocyte-specific overexpression of ERα (ERα-OE) and subjected them to Myocardial Infarction (MI). At the basal level, female and male ERα-OE mice showed increased Left Ventricular (LV) mass, LV volume and cardiomyocyte length. Two weeks after MI, LV volume was significantly increased and LV wall thickness decreased in female and male WT-mice and male ERα-OE, but not in female ERα-OE mice. ERα-OE enhanced expression of angiogenesis and lymphangiogenesis markers (Vegf, Lyve-1), and neovascularization in the peri-infarct area in both sexes. However, attenuated level of fibrosis and higher phosphorylation of JNK signaling pathway could be detected only in female ERα-OE after MI. In conclusion, our study indicates that ERα protects female mouse cardiomyocytes from the sequelae of ischemia through induction of neovascularization in a paracrine fashion and impaired fibrosis, which together may contribute to the attenuation of cardiac remodelling.

Sex differences in exercise-induced physiological myocardial hypertrophy are modulated by oestrogen receptor beta.

AIMS: Oestrogen receptor alpha (ERα) and beta (ERß) are involved in the regulation of pathological myocardial hypertrophy (MH). We hypothesize that both ER are also involved in physiological MH. Therefore, we investigated the role of ER in exercise-induced physiological MH in loss-of-function models and studied potential mechanisms of action. METHODS AND RESULTS: We performed 1 and 8 weeks of voluntary cage wheel running (VCR) with male and female C57BL/6J wild-type (WT), ERα- and ERß-deleted mice. In line with other studies, female WT mice ran more than males (P ≤ 0.001). After 8 weeks of VCR, both sexes showed an increase in left ventricular mass (females: P ≤ 0.01 and males: P ≤ 0.05) with more pronounced MH in females (P < 0.05). As previously shown, female ERα-deleted mice run less than female WT mice (P ≤ 0.001). ERß-deleted mice showed similar running performance as WT mice (females vs. male: P ≤ 0.001), but did not develop MH. Only female WT mice showed an increase in phosphorylation of serine/threonine kinase (AKT), ERK1/2, p38-mitogen-activated protein kinase (MAPK), and ribosomal protein s6, as well as an increase in the expression of key regulators of mitochondrial function and mitochondrial respiratory chain proteins (complexes I, III, and V) after VCR. However, ERß deletion abolished all observed sex differences. Mitochondrial remodelling occurred in female WT-VCR mice, but not in female ERß-deleted mice. CONCLUSION: The sex-specific response of the heart to exercise is modulated by ERß. The greater increase in physiological MH in females is mediated by induction of AKT signalling, MAPK pathways, protein synthesis, and mitochondrial adaptation via ERß.

Sex- and estrogen-dependent regulation of a miRNA network in the healthy and hypertrophied heart.

BACKGROUND: In pressure overload, profibrotic gene expression and cardiac fibrosis are more pronounced in males than in females. Sex-specific and estrogen-dependent regulation of microRNAs (miRNAs), such as miR-21, may be a potential mechanism leading to sex differences in fibrosis. OBJECTIVES: To analyze the influence of sex, estrogen, and estrogen receptor beta (ERß) on the expression of miR-21 and to identify additional miRNAs potentially involved in sex-specific pressure overload-induced cardiac remodeling. METHODS: The sex-specific regulation of fibrosis-related miRNAs was analyzed in male and female wild type and ERß-deficient mice after transverse aortic constriction (TAC), in rat fibroblasts, and in a cardiomyocyte-like cell line. RESULTS: We report the sex-specific expression of functionally-related miR-21, -24, -27a, -27b, 106a, -106b and the regulation of their expression by estrogen in a sex-specific manner. These effects were abolished in ERß-deficient mice. We demonstrate the presence of common functional target sites for these miRNAs on three repressors of the mitogen-activated protein kinase signaling pathway, i.e. Rasa1, Rasa2 and Spry1, which may all lead to cardiac fibrosis. As expected, transfection with miRNA mimics targeting these repressors induced ERK1/2 phosphorylation. CONCLUSIONS: Estrogen regulates a network of miRNAs in a sex-specific manner via ERß. Our data suggest that the sex-specific expression of these miRNAs may be related to sex differences in fibrosis after pressure overload.

17ß-Estradiol-induced interaction of ERα with NPPA regulates gene expression in cardiomyocytes.

AIMS: 17ß-Oestradiol (E2) and its receptors (ERα and ERß) are important regulators of physiological and pathological processes in the cardiovascular system. ER act in concert with other regulatory factors mediating oestrogenic effects. However, the underlying mechanisms modulating ER transcriptional activity are not fully elucidated. To gain better understanding of E2-induced ERα action in the human heart, we aimed to identify and functionally analyse interaction partners of ERα. METHODS AND RESULTS: Using yeast two-hybrid assays with a human heart cDNA library, we identified atrial natriuretic peptide precursor A (NPPA), a well-known cardiac hypertrophy marker, as a novel ERα interaction partner interacting in an E2-dependent manner. Mutation analyses and immunofluorescence data indicated that the LXXLL motif within NPPA is necessary for its E2-induced interaction with ERα, its action as a co-repressor of ERα, and its translocation into the nucleus of human and rat cardiomyocytes. Expression analysis and chromatin immunoprecipitation assays in a human left ventricular cardiomyocyte cell line, AC16, showed that NPPA interacts with E2/ERα, suppressing the transcriptional activity of ERα on E2-target genes, such as NPPA, connexin43, αactinin-2, nuclear factor of activated T-cells, and collagens I and III. CONCLUSION: We characterize for the first time an E2-regulated interaction of NPPA with ERα in cardiomyocytes, that may be crucial in physiological and/or pathological cardiac processes, thereby representing a potential therapeutic target.

Regression of myocardial hypertrophy after aortic valve replacement: faster in women?

BACKGROUND: In patients with aortic stenosis, pressure overload induces cardiac hypertrophy and fibrosis. Female sex and estrogens influence cardiac remodeling and fibrosis in animal models and in men. Sex differences and their molecular mechanisms in hypertrophy regression after aortic valve replacement have not yet been studied. METHODS AND RESULTS: We prospectively obtained preoperative and early postoperative echocardiography in 92 patients, 53 women and 39 men, undergoing aortic valve replacement for isolated aortic stenosis. We analyzed in a subgroup of 10 patients matrix gene expression in left ventricular (LV) biopsies. In addition, we determined the effect of 17ß-estradiol on collagen synthesis in isolated rat cardiac fibroblasts. Preoperatively, women and men had similar ejection fraction. Similar percentages of women and men had increased LV diameters (37% and 38%). Women more frequently exhibited LV hypertrophy than men (women: 86%; men: 56%; P<0.01). Postoperatively, increased LV diameters persisted in 34% of men but only in 12% of women (P<0.023). LV hypertrophy reversed more frequently in women than in men, leading to a similar prevalence of LV hypertrophy after surgery (women: 45%; men: 36%). In surgical biopsies, men had significantly higher collagen I and III and matrix metalloproteinase 2 gene expression than women. In isolated rat cardiac fibroblasts, 17ß-estradiol significantly increased collagen I and III gene expressions in male cells but decreased it in female cells. CONCLUSIONS: Women adapt to pressure overload differently from men. Less fibrosis before surgery may enable faster regression after surgery.

Female sex and estrogen receptor-beta attenuate cardiac remodeling and apoptosis in pressure overload.

We investigated sex differences and the role of estrogen receptor-beta (ERbeta) on myocardial hypertrophy in a mouse model of pressure overload. We performed transverse aortic constriction (TAC) or sham surgery in male and female wild-type (WT) and ERbeta knockout (ERbeta(-/-)) mice. All mice were characterized by echocardiography and hemodynamic measurements and were killed 9 wk after surgery. Left ventricular (LV) samples were analyzed by microarray profiling, real-time RT-PCR, and histology. After 9 wk, WT males showed more hypertrophy and heart failure signs than WT females. Notably, WT females developed a concentric form of hypertrophy, while males developed eccentric hypertrophy. ERbeta deletion augmented the TAC-induced increase in cardiomyocyte diameter in both sexes. Gene expression profiling revealed that WT male hearts had a stronger induction of matrix-related genes and a stronger repression of mitochondrial genes than WT female hearts. ERbeta(-/-) mice exhibited a different transcriptional response. ERbeta(-/-)/TAC mice of both sexes exhibited induction of proapoptotic genes with a stronger expression in ERbeta(-/-) males. Cardiac fibrosis was more pronounced in male WT/TAC than in female mice. This difference was abolished in ERbeta(-/-) mice. The number of apoptotic nuclei was increased in both sexes of ERbeta(-/-)/TAC mice, most prominent in males. Female sex offers protection against ventricular chamber dilation in the TAC model. Both female sex and ERbeta attenuate the development of fibrosis and apoptosis, thus slowing the progression to heart failure.

17beta-Estradiol inhibits matrix metalloproteinase-2 transcription via MAP kinase in fibroblasts.

AIMS: Female sex and sex hormones contribute to cardiac remodelling. 17beta-estradiol (E2) is involved in the modulation of extracellular matrix composition and function. Here, we analysed the effect of E2 on matrix metalloproteinase (MMP)-2 gene expression and studied the underlying molecular mechanisms in rat cardiac fibroblasts and in a human fibroblast cell line. METHODS AND RESULTS: In adult rat cardiac fibroblasts, E2 significantly decreased MMP-2 gene expression in an estrogen receptor (ER)-dependent manner. Transient transfection experiments of human MMP-2 (hMMP-2) promoter deletion constructs in a human fibroblast cell line revealed a regulatory region between -324 and -260 bp that is involved in E2/ERalpha-mediated repression of hMMP-2 gene transcription. Electrophoretic mobility shift assays (EMSA) and supershift analysis demonstrated the binding of transcription factor Elk-1 within this promoter region. Elk-1 was phosphorylated by E2 via the mitogen-activated protein kinase (MAPK) signalling pathway as shown by western blotting. Treatment of cells with the MAPK inhibitor PD98059 blocked the E2-dependent repression of hMMP-2 promoter activity as well as the endogenous MMP-2 mRNA levels in both human fibroblast cells and rat cardiac fibroblasts. CONCLUSION: E2 inhibits MMP-2 expression via the ER and the MAPK pathway in rat cardiac fibroblasts and in a human fibroblast cell line. These mechanisms may contribute to sex-specific differences in fibrotic processes that are observed in human heart and other diseases.

Nuclear factor-kappaB regulates estrogen receptor-alpha transcription in the human heart.

Estrogen receptor (ER)-mediated effects have been associated with the modulation of myocardial hypertrophy in animal models and in humans, but the regulation of ER expression in the human heart has not yet been analyzed. In various cell lines and tissues, multiple human estrogen receptor alpha (hERalpha) mRNA isoforms are transcribed from distinct promoters and differ in their 5'-untranslated regions. Using PCR-based strategies, we show that in the human heart the ERalpha mRNA is transcribed from multiple promoters, namely, A, B, C, and F, of which the F-promoter is most frequently used variant. Transient transfection reporter assays in a human cardiac myocyte cell line (AC16) with F-promoter deletion constructs demonstrated a negative regulatory region within this promoter. Site-directed mutagenesis and electrophoretic mobility shift assays indicated that NF-kappaB binds to this region. An inhibition of NF-kappaB activity by parthenolide significantly increased the transcriptional activity of the F-promoter. Increasing NF-kappaB expression by tumor necrosis factor-alpha reduced the expression of ERalpha, indicating that the NF-kappaB pathway inhibits expression of ERalpha in human cardiomyocytes. Finally, 17beta-estradiol induced the transcriptional activity of hERalpha promoters A, B, C, and F. In conclusion, inflammatory stimuli suppress hERalpha expression via activation and subsequent binding of NF-kappaB to the ERalpha F-promoter, and 17beta-estradiol/hERalpha may antagonize the inhibitory effect of NF-kappaB. This suggests interplay between estrogen/estrogen receptors and the pro-hypertrophic and inflammatory responses to NF-kappaB.