Models of Gender Differences in Cardiovascular Disease

Vascular protein disulfide isomerase A1 mediates endothelial dysfunction induced by angiotensin II in mice

AIM

Protein disulfide isomerases (PDIs) are involved in platelet aggregation and intravascular thrombosis, but their role in regulating endothelial function is unclear. Here, we characterized the involvement of vascular PDIA1 in angiotensin II (Ang II)-induced endothelial dysfunction in mice.

METHODS

Endothelial dysfunction was induced in C57BL/6JCmd male mice via Ang II subcutaneous infusion, and PDIA1 was inhibited with bepristat. Endothelial function was assessed in vivo with magnetic resonance imaging and ex vivo with a myography, while arterial stiffness was measured as pulse wave velocity. Nitric oxide (NO) bioavailability was measured in the aorta (spin-trapping electron paramagnetic resonance) and plasma (NO2 - and NO3 - levels). Oxidative stress, eNOS uncoupling (DHE-based aorta staining), and thrombin activity (thrombin-antithrombin complex; calibrated automated thrombography) were evaluated.

RESULTS

The inhibition of PDIA1 by bepristat in Ang II-treated mice prevented the impairment of NO-dependent vasodilation in the aorta as evidenced by the response to acetylcholine in vivo, increased systemic NO bioavailability and the aortic NO production, and decreased vascular stiffness. Bepristat's effect on NO-dependent function was recapitulated ex vivo in Ang II-induced endothelial dysfunction in isolated aorta. Furthermore, bepristat diminished the Ang II-induced eNOS uncoupling and overproduction of ROS without affecting thrombin activity.

CONCLUSION

In Ang II-treated mice, the inhibition of PDIA1 normalized the NO-ROS balance, prevented endothelial eNOS uncoupling, and, thereby, improved vascular function. These results indicate the importance of vascular PDIA1 in regulating endothelial function, but further studies are needed to elucidate the details of the mechanisms involved.

Impact of age and sex on myelopoiesis and inflammation during myocardial infarction

Of all the different risk factors known to cause cardiovascular disease (CVD), age and sex are considered to play a crucial role. Aging follows a continuum from birth to death, and therefore it inevitably acts as a risk for CVD. Along with age, sex differences have also been shown to demonstrate variations in immune system responses to pathological insults. It has been widely perceived that females are protected against myocardial infarction (MI) and the protection is quite apparent in young vs. old women. Acute MI leads to changes in the population of myeloid and lymphoid cells at the injury site with myeloid bias being observed in the initial inflammation and the lymphoid in the late-resolution phases of the pathology. Multiple evidence demonstrates that aging enhances damage to various cellular processes through inflamm-aging, an inflammatory process identified to increase pro-inflammatory markers in circulation and tissues. Following MI, marked changes were observed in different sub-sets of major myeloid cell types viz., neutrophils, monocytes, and macrophages. There is a paucity of information regarding the tissue and site-specific functions of these sub-sets. In this review, we highlight the importance of age and sex as crucial risk factors by discussing their role during MI-induced myelopoiesis while emphasizing the current status of myeloid cell sub-sets. We further put forth the need for designing and executing age and sex interaction studies aimed to determine the appropriate age and sex to develop personalized therapeutic strategies post-MI.

The double-hit protocol induces HFpEF and impairs myocardial ubiquitin-proteasome system performance in FVB/N mice

Heart failure with preserved ejection fraction (HFpEF) is a leading cause of death and disability, with its prevalence surpassing that of heart failure with reduced ejection fraction. Obesity and hypertension are often associated with HFpEF. HFpEF can be modeled through simultaneous metabolic and hypertensive stresses in male C57BL/6N mice provoked by a combination treatment of a high-fat diet (HFD) and constitutive nitric oxide synthase inhibition by Nω-nitro-L-arginine methyl-ester (L-NAME). Ubiquitin-proteasome system (UPS) dysfunction was detected in many forms of cardiomyopathy, but whether it occurs in HFpEF remains unknown. We report successful modeling of HFpEF in male FVB/N mice and, by taking advantage of a transgenic UPS reporter mouse, we have detected myocardial UPS functioning impairment during HFpEF, suggesting a pathogenic role for impaired protein degradation in the development and progression of HFpEF.

Effects of Sex on the Susceptibility for Atrial Fibrillation in Pigs with Ischemic Heart Failure

Atrial fibrillation (AF) is the most prevalent arrhythmia, often caused by myocardial ischemia/infarction (MI). Men have a 1.5× higher prevalence of AF, whereas women show a higher risk for new onset AF after MI. However, the underlying mechanisms of how sex affects AF pathophysiology are largely unknown. In 72 pigs with/without ischemic heart failure (IHF) we investigated the impact of sex on ischemia-induced proarrhythmic atrial remodeling and the susceptibility for AF. Electrocardiogram (ECG) and electrophysiological studies were conducted to assess electrical remodeling; histological analyses were performed to assess atrial fibrosis in male and female pigs. IHF pigs of both sexes showed a significantly increased vulnerability for AF, but in male pigs more and longer episodes were observed. Unchanged conduction properties but enhanced left atrial fibrosis indicated structural rather than electrical remodeling underlying AF susceptibility. Sex differences were only observed in controls with female pigs showing an increased intrinsic heart rate, a prolonged QRS interval and a prolonged sinus node recovery time. In sum, susceptibility for AF is significantly increased both in male and female pigs with ischemic heart failure. Differences between males and females are moderate, including more and longer AF episodes in male pigs and sinus node dysfunction in female pigs.

Deletion of the P2Y2 receptor aggravates internal elastic lamina calcification in chronic kidney disease mice through upregulation of alkaline phosphatase and lipocalin-2

Calcification of the medial layer, inducing arterial stiffness, contributes significantly to cardiovascular mortality in patients with chronic kidney disease (CKD). Extracellular nucleotides block the mineralization of arteries by binding to purinergic receptors including the P2Y₂ receptor. This study investigates whether deletion of the P2Y₂ receptor influences the development of arterial media calcification in CKD mice. Animals were divided into: (i) wild type mice with normal renal function (control diet) (n = 8), (ii) P2Y₂ R^-/- mice with normal renal function (n = 8), (iii) wild type mice with CKD (n = 27), and (iv) P2Y₂ R^-/- mice with CKD (n = 22). To induce CKD, animals received an alternating (0.2-0.3%) adenine diet for 7 weeks. All CKD groups developed a similar degree of chronic renal failure as reflected by high serum creatinine and phosphorus levels. Also, the presence of CKD induced calcification in the heart and medial layer of the aortic wall. However, deletion of the P2Y₂ receptor makes CKD mice more susceptible to the development of calcification in the heart and aorta (aortic calcium scores (median ± IQR), CKD-wild type: 0.34 ± 4.3 mg calcium/g wet tissue and CKD-P2Y₂ R^-/- : 4.0 ± 13.2 mg calcium/g wet tissue). As indicated by serum and aortic mRNA markers, this P2Y₂ R^-/- mediated increase in CKD-related arterial media calcification was associated with an elevation of calcification stimulators, including alkaline phosphatase and inflammatory molecules interleukin-6 and lipocalin 2. The P2Y₂ receptor should be considered as an interesting therapeutic target for tackling CKD-related arterial media calcification.

Inhibition of Trimethylamine N-Oxide Attenuates Neointimal Formation Through Reduction of Inflammasome and Oxidative Stress in a Mouse Model of Carotid Artery Ligation

Aims: Trimethylamine-N-oxide (TMAO) is a metabolite generated from dietary choline, betaine, and l-carnitine, after their oxidization in the liver. TMAO has been identified as a novel independent risk factor for atherosclerosis through the induction of vascular inflammation. However, the effect of TMAO on neointimal formation in response to vascular injury remains unclear. Results: This study was conducted using a murine model of acutely disturbed flow-induced atherosclerosis induced by partial carotid artery ligation. 3,3-Dimethyl-1-butanol (DMB) was used to reduce TMAO concentrations. Wild-type mice were divided into four groups [regular diet, high-TMAO diet, high-choline diet, and high-choline diet+DMB] to investigate the effects of TMAO elevation and its inhibition by DMB. Mice fed high-TMAO and high-choline diets had significantly enhanced neointimal hyperplasia and advanced plaques, elevated arterial elastin fragmentation, increased macrophage infiltration and inflammatory cytokine secretion, and enhanced activation of nuclear factor (NF)-κB, the NLRP3 inflammasome, and endoplasmic reticulum (ER) stress relative to the control group. Mice fed high-choline diets with DMB treatment exhibited attenuated flow-induced atherosclerosis, inflammasome expression, ER stress, and reactive oxygen species expression. Human aortic smooth muscle cells (HASMCs) were used to investigate the mechanism of TMAO-induced injury. The HASMCs were treated with TMAO with or without an ER stress inhibitor to determine whether inhibition of ER stress modulates the TMAO-induced inflammatory response. Innovation: This study demonstrates that TMAO regulates vascular remodeling via ER stress. Conclusion: Our findings demonstrate that TMAO elevation promotes disturbed flow-induced atherosclerosis and that DMB administration mitigates vascular remodeling, suggesting a rationale for a TMAO-targeted strategy for the treatment of atherosclerosis. Antioxid. Redox Signal. 38, 215-233.

Large and Small Animal Models of Heart Failure With Reduced Ejection Fraction

Heart failure (HF) describes a heterogenous complex spectrum of pathological conditions that results in structural and functional remodeling leading to subsequent impairment of cardiac function, including either systolic dysfunction, diastolic dysfunction, or both. Several factors chronically lead to HF, including cardiac volume and pressure overload that may result from hypertension, valvular lesions, acute, or chronic ischemic injuries. Major forms of HF include hypertrophic, dilated, and restrictive cardiomyopathy. The severity of cardiomyopathy can be impacted by other comorbidities such as diabetes or obesity and external stress factors. Age is another major contributor, and the number of patients with HF is rising worldwide in part due to an increase in the aged population. HF can occur with reduced ejection fraction (HF with reduced ejection fraction), that is, the overall cardiac function is compromised, and typically the left ventricular ejection fraction is lower than 40%. In some cases of HF, the ejection fraction is preserved (HF with preserved ejection fraction). Animal models play a critical role in facilitating the understanding of molecular mechanisms of how hearts fail. This review aims to summarize and describe the strengths, limitations, and outcomes of both small and large animal models of HF with reduced ejection fraction that are currently used in basic and translational research. The driving defect is a failure of the heart to adequately supply the tissues with blood due to impaired filling or pumping. An accurate model of HF with reduced ejection fraction would encompass the symptoms (fatigue, dyspnea, exercise intolerance, and edema) along with the pathology (collagen fibrosis, ventricular hypertrophy) and ultimately exhibit a decrease in cardiac output. Although countless experimental studies have been published, no model completely recapitulates the full human disease. Therefore, it is critical to evaluate the strength and weakness of each animal model to allow better selection of what animal models to use to address the scientific question proposed.

Quantification of myocardial fibrosis using noninvasive T2-mapping magnetic resonance imaging: Preclinical models of aging and pressure overload

Noninvasive imaging of cardiac fibrosis is important for early diagnosis and intervention in chronic heart diseases. Here, we investigated whether noninvasive, contrast agent-free MRI T₂ -mapping can quantify myocardial fibrosis in preclinical models of aging and pressure overload. Myocardial fibrosis and remodeling were analyzed in two animal models: (i) aging (15-month-old male CF-1 mice vs. young 6- to 8-week-old mice), and (ii) pressure overload (PO; by transverse aortic constriction in 4- to 5-month-old male C57BL/6 mice vs. sham-operated for 14 days). In vivo T₂ -mapping was performed by acquiring data during the isovolumic and early diastolic phases, with a modified respiratory and ECG-triggered multiecho TurboRARE sequence on a 7-T MRI. Cine MRI provided cardiac morphology and function. A quantitative segmentation method was developed to analyze the in vivo T₂ -maps of hearts at midventricle, apex, and basal regions. The cardiac fibrosis area was analyzed ex vivo by picro sirius red (PSR) staining. Both aged and pressure-overloaded hearts developed significant myocardial contractile dysfunction, cardiac hypertrophy, and interstitial fibrosis. The aged mice had two phenotypes, fibrotic and mild-fibrotic. Notably, the aged fibrotic subgroup and the PO mice showed a marked decrease in T₂ relaxation times (25.3 ± 0.6 in aged vs. 29.9 ± 0.7 ms in young mice, p = 0.002; and 24.3 ± 1.7 in PO vs. 28.7 ± 0.7 ms in shams, p = 0.05). However, no significant difference in T₂ was detected between the aged mild-fibrotic subgroup and the young mice. Accordingly, an inverse correlation between myocardial fibrosis percentage (FP) and T₂ relaxation time was derived (R²  = 0.98): T₂ (ms) = 30.45 - 1.05 × FP. Thus, these results demonstrate a statistical agreement between T₂ -map-quantified fibrosis and PSR staining in two different clinically relevant animal models. In conclusion, T₂ -mapping MRI is a promising noninvasive contrast agent-free quantitative technique to characterize myocardial fibrosis.

Dihydroartemisinin improves hypercholesterolemia in ovariectomized mice via enhancing vectorial transport of cholesterol and bile acids from blood to bile

The increase of concentrations of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) in the serum of postmenopausal women is the important risk factor of the high morbidity of cardiovascular diseases of old women worldwide. To test the anti-hypercholesterolemia function of dihydroartemisinin (DHA) in postmenopausal women, ovariectomized (OVX) mice were generated, and DHA were administrated to OVX mice for 4 weeks. The blood and liver tissues were collected for biochemical and histological tests respectively. The mRNA and protein expression levels of genes related to metabolism and transport of cholesterol, bile acid and fatty acid in the liver or ileum were checked through qPCR and western blot. DHA could significantly reduce the high concentrations of TC and LDL-C in the serum and the lipid accumulation in the liver of ovariectomized mice. The expression of ABCG5/8 was reduced in liver of OVX mice, and DHA could up-regulate the expression of them. Genes of transport proteins for bile salt transport from blood to bile, including Slc10a1, Slco1b2 and Abcb11, were also significantly up-regulated by DHA. DHA also down-regulated the expression of Slc10a2 in the ileum of OVX mice to reduce the absorption of bile salts. Genes required for fatty acid synthesis and uptake, such as Fasn and CD36, were reduced in the liver of OVX mice, and DHA administration could significantly up-regulate the expression of them. These results demonstrated that DHA could improve hypercholesterolemia in OVX mice through enhancing the vectorial transport of cholesterol and bile acid from blood to bile.

Sex bias in alcohol research: A 20-year comparative study

We aimed to assess the sex-inclusive and sex-based analysis bias in alcohol research for the past 20 years. Data were abstracted from 2988 original research articles published from 2000 through 2019 in 51 representative journals across 9 biomedical disciplines. An analysis in 5-year intervals revealed that the percentage of studies using participants of both sexes was significantly higher between 2015 and 2019 than between 2000 and 2014. When stratified, clinical studies showed a higher percentage of both-sex studies compared to basic studies using animals. The reasons for the use of single-sex cohorts mainly included insufficient participant numbers and misconceptions surrounding the hormonal variability of females. Implementation of the NIH SABV policy promoted the ratio of NIH-funded papers with sex-based analyses. In conclusion, sex bias in alcohol-related biomedical studies has improved over the past 20 years, particularly after the implementation of the SABV policy. Although clinical studies increasingly included sex-based analysis, basic studies were biased towards the use of males.

Clinical and pathological findings in rabbits with cardiovascular disease: 59 cases (2001-2018)

OBJECTIVE

To determine epidemiological features of cardiovascular disease in rabbits examined at a veterinary teaching hospital and characterize clinical and pathological findings.

ANIMALS

59 rabbits.

PROCEDURES

Medical records from 2001 to 2018 were reviewed, and data were collected. Echocardiographic images and histologic diagnoses were reviewed.

RESULTS

The prevalence of cardiovascular disease was 2.6% (59/2,249). Clinical signs related to cardiac disease included heart murmur (n = 25 rabbits), arrhythmia (22), tachypnea or dyspnea (13), hyporexia or anorexia (13), and muscle wasting (9). Radiographic (n = 39) abnormalities included cardiomegaly (19) and peritoneal (12) and pleural (11) effusion. Common echocardiographic (n = 37) diagnoses included degenerative valve disease (15), dilated cardiomyopathy (7), unclassified cardiomyopathy (4), restrictive cardiomyopathy (3), and hypertrophic cardiomyopathy (2). On ECG (n = 19), supraventricular arrhythmias (16) were more common than ventricular arrhythmias (12). Thirty-five necropsy reports were available, and diagnoses included cardiomyopathy (n = 14), myocarditis (10), and arteriosclerosis (9). Medical management (n = 20) included a wide range of drugs and dosages with few adverse effects. Survival times (n = 36 rabbits) ranged from 1 to 2,353 days with a median cardiac disease-specific survival time of 306 days.

CONCLUSIONS AND CLINICAL RELEVANCE

The findings provided information on the prevalence of cardiovascular disease in rabbits and survival times for affected rabbits. Right-sided, left-sided, and biventricular congestive heart failure occurred equally. Median survival time was lower than that reported for other species. Further research on the diagnosis and treatment of cardiovascular disease in rabbits is needed.

Cardiac GRK2 Protein Levels Show Sexual Dimorphism during Aging and Are Regulated by Ovarian Hormones

Cardiovascular disease (CVD) risk shows a clear sexual dimorphism with age, with a lower incidence in young women compared to age-matched men. However, this protection is lost after menopause. We demonstrate that sex-biased sensitivity to the development of CVD with age runs in parallel with changes in G protein-coupled receptor kinase 2 (GRK2) protein levels in the murine heart and that mitochondrial fusion markers, related to mitochondrial functionality and cardiac health, inversely correlate with GRK2. Young female mice display lower amounts of cardiac GRK2 protein compared to age-matched males, whereas GRK2 is upregulated with age specifically in female hearts. Such an increase in GRK2 seems to be specific to the cardiac muscle since a different pattern is found in the skeletal muscles of aging females. Changes in the cardiac GRK2 protein do not seem to rely on transcriptional modulation since adrbk1 mRNA does not change with age and no differences are found between sexes. Global changes in proteasomal or autophagic machinery (known regulators of GRK2 dosage) do not seem to correlate with the observed GRK2 dynamics. Interestingly, cardiac GRK2 upregulation in aging females is recapitulated by ovariectomy and can be partially reversed by estrogen supplementation, while this does not occur in the skeletal muscle. Our data indicate an unforeseen role for ovarian hormones in the regulation of GRK2 protein levels in the cardiac muscle which correlates with the sex-dependent dynamics of CVD risk, and might have interesting therapeutic applications, particularly for post-menopausal women.

Comparison of metabolic and functional parameters using cardiac 18F-FDG-PET in early to mid-adulthood male and female mice

BACKGROUND

In this descriptive study of male and female mice at different weeks of age, we use serial non-invasive cardiac 18F-FDG-PET scans to follow up on metabolic alterations, heart function parameters, and the ECG of both sexes in early to mid-adulthood.

METHODS

ECG-gated 18F-FDG-PET scans were performed in mice on 10, 14, and 18 weeks of age, using a dedicated small-animal PET scanner. The percentage of the injected activity per gram (%IA/g) in the heart, left ventricular metabolic volume (LVMV), myocardial viability and left ventricular function parameters: end-diastolic (EDV), end-systolic (ESV), stroke volume (SV), and the ejection fraction (EF%) were estimated.

RESULTS

Compared to their age-matched female counterpart, male mice showed a constant increase in LVMV and ventricular volume during the follow-up. In contrast, female mice remain stable after ten weeks of age. Furthermore, male mice showed lower heart rates, positive correlation with cardiac %IA/g, and negative correlation with LVMV.

CONCLUSION

In this study of serial cardiac PET scans, we provide insight for basic murine research models, showing that mice gender and age show distinct cardiac metabolisms. These physiologic alterations need to be considered when planning in vivo injury models to avoid potential pitfalls.

Therapeutic Ultrasound in Cardiovascular Medicine

An advantage of therapeutic ultrasound (US) is the ability to cause controlled biological effects noninvasively. Depending on the magnitude and frequency of exposure parameters, US can interact in different ways with a variety of biological tissues. The development and clinical utility of therapeutic US techniques are now rapidly growing, especially with regard to the application of US pulses for cardiac pacing and the potential treatment of cardiovascular diseases. This review outlines the basic principles of US-based therapy in cardiology, including the acoustic properties of the cardiovascular tissue, and the use of US in therapeutic cardiovascular medicine.

A chalcone derivative, 1m-6, exhibits atheroprotective effects by increasing cholesterol efflux and reducing inflammation-induced endothelial dysfunction

BACKGROUND AND PURPOSE

Atherosclerosis, resulting from lipid dysregulation and vascular inflammation, causes atherosclerotic cardiovascular disease (ASCVD), which contributes to morbidity and mortality worldwide. Chalcone and its derivatives possess beneficial properties, including anti-inflammatory, antioxidant and antitumour activity with unknown cardioprotective effects. We aimed to develop an effective chalcone derivative with antiatherogenic potential.

EXPERIMENTAL APPROACH

Human THP-1 cells and HUVECs were used as in vitro models. Western blots and real-time PCRs were performed to quantify protein, mRNA and miRNA expressions. The cholesterol efflux capacity was assayed by ³ H labelling of cholesterol. LDL receptor knockout (Ldlr^-/- ) mice fed a high-fat diet were used as an in vivo atherogenesis model. Haematoxylin and eosin and oil red O staining were used to analyse plaque formation.

KEY RESULTS

Using ATP-binding cassette transporter A1 (ABCA1) expression we identified the chalcone derivative, 1m-6, which enhances ABCA1 expression and promotes cholesterol efflux in THP-1 macrophages. Moreover, 1m-6 stabilizes ABCA1 mRNA and suppresses the expression of potential ABCA1-regulating miRNAs through nuclear factor erythroid 2-related factor 2 (Nrf2)/haem oxygenase-1 (HO-1) signalling. Additionally, 1m-6 significantly inhibits TNF-α-induced expression of adhesion molecules, vascular cell adhesion molecule 1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1), plus production of proinflammatory cytokines via inhibition of JAK/STAT3 activation and the modulation of Nrf2/HO-1 signalling in HUVECs. In atherosclerosis-prone mice, 1m-6 significantly reduces lipid accumulation and atherosclerotic plaque formation.

CONCLUSION AND IMPLICATIONS

Our study demonstrates that 1m-6 produces promising atheroprotective effects by enhancing cholesterol efflux and suppressing inflammation-induced endothelial dysfunction, which opens a new avenue for treating ASCVD.

LINKED ARTICLES

This article is part of a themed issue on Risk factors, comorbidities, and comedications in cardioprotection. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.23/issuetoc.

Approaching Sex Differences in Cardiovascular Non-Coding RNA Research

Cardiovascular disease (CVD) is the biggest cause of sickness and mortality worldwide in both males and females. Clinical statistics demonstrate clear sex differences in risk, prevalence, mortality rates, and response to treatment for different entities of CVD. The reason for this remains poorly understood. Non-coding RNAs (ncRNAs) are emerging as key mediators and biomarkers of CVD. Similarly, current knowledge on differential regulation, expression, and pathology-associated function of ncRNAs between sexes is minimal. Here, we provide a state-of-the-art overview of what is known on sex differences in ncRNA research in CVD as well as discussing the contributing biological factors to this sex dimorphism including genetic and epigenetic factors and sex hormone regulation of transcription. We then focus on the experimental models of CVD and their use in translational ncRNA research in the cardiovascular field. In particular, we want to highlight the importance of considering sex of the cellular and pre-clinical models in clinical studies in ncRNA research and to carefully consider the appropriate experimental models most applicable to human patient populations. Moreover, we aim to identify sex-specific targets for treatment and diagnosis for the biggest socioeconomic health problem globally.

Both male and female obese ZSF1 rats develop cardiac dysfunction in obesity-induced heart failure with preserved ejection fraction

Heart failure with a preserved ejection fraction (HFpEF) is associated with multiple comorbidities, such as old age, hypertension, type 2 diabetes and obesity and is more prevalent in females. Although the male obese ZSF1 rat has been proposed as a suitable model to study the development of diastolic dysfunction and early HFpEF, studies in female animals have not been performed yet. Therefore, we aimed to characterize the cardiac phenotype in female obese ZSF1 rats and their lean counterparts. Additionally, we aimed to investigate whether differences exist in disease progression in obese male and female ZSF1 rats. Therefore, male and female ZSF1 rats, lean as well as obese (N = 6-9/subgroup), were used. Every two weeks, from 12 to 26 weeks of age, systolic blood pressure and echocardiographic measurements were performed, and venous blood was sampled. Female obese ZSF1 rats, as compared to female lean ZSF1 rats, developed diastolic dysfunction with cardiac hypertrophy and fibrosis in the presence of severe dyslipidemia, increased plasma growth differentiation factor 15 and mild hypertension, and preservation of systolic function. Although obese female ZSF1 rats did not develop hyperglycemia, their diastolic dysfunction was as severe as in the obese males. Taken together, the results from the present study suggest that the female obese ZSF1 rat is a relevant animal model for HFpEF with multiple comorbidities, suitable for investigating novel therapeutic interventions.

C1q/TNF-related protein 5 contributes to diabetic vascular endothelium dysfunction through promoting Nox-1 signaling

OBJECTIVE

Dysregulated adipokine profiles contribute to the pathogenesis of diabetic cardiovascular complications. Endothelial cell (EC) dysfunction, a common pathological alteration in cardiovascular disorders, is exaggerated in diabetes. However, it is unclear whether and how dysregulated adipokines may contribute to diabetic EC dysfunction.

METHODS AND RESULTS

Serum C1q/TNF-Related Protein 5 (CTRP5) were determined in control/diabetes patients, and control/diabetic mice (high-fat diet, HFD). We observed for the first time that serum total CTRP5 was increased, high molecular weight (HMW) form was decreased, but the globular form (gCTRP5) was significantly increased in diabetic patients. These pathological alterations were reproduced in diabetic mice. To determine the pathological significance of increased gCTRP5 in diabetes, in vivo, ex vivo and in vitro experiments were performed. Diabetic atherosclerosis and EC dysfunction were significantly attenuated by the in vivo administration of CTRP5 neutralization antibody (CTRP5Ab). EC apoptosis was significantly increased in diabetic EC (isolated from HFD animal aorta) or high glucose high lipid (HGHL) cultured HUVECs. These pathological alterations were further potentiated by gCTRP5 and attenuated by CTRP5Ab. Pathway specific discovery-driven approach revealed that Nox1 expression was one of the signaling molecules commonly activated by HFD, HGHL, and gCTRP5. Treatment with CTRP5Ab reversed HFD-induced Nox1 upregulation. Finally, Nox1siRNA was used to determine the causative role of Nox1 in gCTRP5 induced EC apoptosis in diabetes. Results showed that gCTRP5 activated the mitochondrial apoptotic signal of EC in diabetes, which was blocked by the silencing Nox1 gene.

CONCLUSION

We demonstrated for the first time that gCTRP5 is a novel molecule contributing to diabetic vascular EC dysfunction through Nox1-mediated mitochondrial apoptosis, suggesting that interventions blocking gCTRP5 may protect diabetic EC function, ultimately attenuate diabetic cardiovascular complications.

Sex-specific influence on cardiac structural remodeling and therapy in cardiovascular disease

BACKGROUND

Cardiovascular diseases (CVDs) culminating into heart failure (HF) are major causes of death in men and women. Prevalence and manifestation, however, differ between sexes, since men mainly present with coronary artery disease (CAD) and myocardial infarction (MI), and post-menopausal women predominantly present with hypertension. These discrepancies are probably influenced by underlying genetic and molecular differences in structural remodeling pathways involved in hypertrophy, inflammation, fibrosis, and apoptosis. In general, men mainly develop eccentric forms, while women develop concentric forms of hypertrophy. Besides that, women show less inflammation, fibrosis, and apoptosis upon HF. This seems to emerge, at least partially, from the fact that the underlying pathways might be modulated by estrogen, which changes after menopause due to declining of the estrogen levels.

CONCLUSION

In this review, sex-dependent alterations in adverse cardiac remodeling are discussed for various CVDs. Moreover, potential therapeutic options, like estrogen treatment, are reviewed.

Irisin alleviates pressure overload-induced cardiac hypertrophy by inducing protective autophagy via mTOR-independent activation of the AMPK-ULK1 pathway

In hypertrophic hearts, autophagic flux insufficiency is recognized as a key pathology leading to maladaptive cardiac remodeling and heart failure. This study aimed to illuminate the cardioprotective role and mechanisms of a new myokine and adipokine, irisin, in cardiac hypertrophy and remodeling. Adult male wild-type, mouse-FNDC5 (irisin-precursor)-knockout and FNDC5 transgenic mice received 4 weeks of transverse aortic constriction (TAC) alone or combined with intraperitoneal injection of chloroquine diphosphate (CQ). Endogenous FNDC5 ablation aggravated and exogenous FNDC5 overexpression attenuated the TAC-induced hypertrophic damage in the heart, which was comparable to the protection of irisin against cardiomyocyte hypertrophy induced by angiotensin II (Ang II) or phenylephrine (PE). Accumulated autophagosome and impaired autophagy flux occurred in the TAC-treated myocardium and Ang II- or PE-insulted cardiomyocytes. Irisin deficiency caused reduced autophagy and aggravated autophagy flux failure, whereas irisin overexpression or supplementation induced protective autophagy and improved autophagy flux, which were reversed by autophagy inhibitors Atg5 siRNA, 3-MA and CQ. Irisin boosted the activity of only AMPK but not Akt and MAPK family members in hypertrophic hearts and cultured cardiomyocytes and further activated ULK1 at Ser555 but not Ser757 and did not affect the mTOR-S6K axis. Blockage of AMPK and ULK1 with compund C and SBI-0206965, respectively, both abrogated irisin's protection against cardiomyocyte hypertrophic injury and reversed its induction of both autophagy and autophagy flux. Our results suggest that irisin protects against pressure overload-induced cardiac hypertrophy by inducing protective autophagy and autophagy flux via activating AMPK-ULK1 signaling.

Sex differences in murine myocardium are not exclusively regulated by gonadal hormones

We investigated sex differences in cardiac protein patterns of intact and castrated mice using proteomics and 1D and 2D immunoblotting. To exclude differences concerning developmental aspects gonadectomy was conducted in mature mice at the age of three months. The main sex-related regulation in the protein pattern of the myocardium occurred for proteins involved in metabolic processes whereas only few proteins involved in other pathways underwent a regulation. Many regulated proteins (2/3) displayed a characteristic V form, which means that these proteins are up- or down-regulated in sexually mature compared to young mice and are back-regulated after castration, emphasizing a direct regulation by gonadal hormones. Several other spots (1/3) showed the same male/female regulation or a drastic increase in male/female spot intensity ratio after castration, suggesting either a regulation independent of sex hormones or a removal of an inhibiting feedback mechanism by gonadectomy. Technically, we found that it cannot be expected that a single spot contains only one protein species and that one protein is present in only one spot. We thus propose for proteomic investigations to identify/quantify all spots of a 2-DE pattern to obtain information about protein speciation and its potential importance for function and pathology.

BIOLOGICAL SIGNIFICANCE

Sex related differences in cardiovascular disease, including risk factors, disease manifestation and outcomes, are far from being well understood, and improved biological understanding of these differences in the healthy myocardium is of great importance. We investigated sex related changes of myocardial protein pattern in intact and castrated mice at different ages and found metabolic proteins to be highly regulated, some of which independently from gonadal hormones.

Reduced cardiotoxicity and increased oral efficacy of artemether polymeric nanocapsules in Plasmodium berghei-infected mice

Artemether (ATM) cardiotoxicity, its short half-life and low oral bioavailability are the major limiting factors for its use to treat malaria. The purposes of this work were to study free-ATM and ATM-loaded poly-ε-caprolactone nanocapules (ATM-NC) cardiotoxicity and oral efficacy on Plasmodium berghei-infected mice. ATM-NC was obtained by interfacial polymer deposition and ATM was associated with polymeric NC oily core. For cardiotoxicity evaluation, male black C57BL6 uninfected or P. berghei-infected mice received, by oral route twice daily/4 days, vehicle (sorbitol/carboxymethylcellulose), blank-NC, free-ATM or ATM-NC at doses 40, 80 or 120 mg kg-1. Electrocardiogram (ECG) lead II signal was obtained before and after treatment. For ATM efficacy evaluation, female P. berghei-infected mice were treated the same way. ATM-NC improved antimalarial in vivo efficacy and reduced mice mortality. Free-ATM induced significantly QT and QTc intervals prolongation. ATM-NC (120 mg kg-1) given to uninfected mice reduced QT and QTc intervals prolongation 34 and 30%, respectively, compared with free-ATM. ATM-NC given to infected mice also reduced QT and QTc intervals prolongation, 28 and 27%, respectively. For the first time, the study showed a nanocarrier reducing cardiotoxicity of ATM given by oral route and it was more effective against P. berghei than free-ATM as monotherapy.

The Negative Chronotropic Effect in Rat Heart Stimulated by Ultrasonic Pulses: Role of Sex and Age

OBJECTIVES

The goal of this study is to investigate the role of sex and age of the negative chronotropic effect after exposure of 3.5-MHz pulsed ultrasound (US) to the rat heart.

METHODS

Forty F344 rats were exposed transthoracically to ultrasonic pulses at a duty factor of approximately 1.0% at 2.0-MPa peak rarefactional pressure amplitude. The transthoracic ultrasonic bursts were delivered consecutively in five 10-s intervals, that is, 10 s of 6-Hz pulse repetition frequency (PRF), 10 s of 5-Hz PRF, 10 s of 4-Hz PRF, 10 s of 5-Hz PRF, and 10 s of 6-Hz, for a 50-s total exposure duration. The rats were divided into 8 groups (n = 5 each): US young male, control young male, US young female, control young female, US old male, control old male, US old female, and control old female.

RESULTS

Two-way ANOVA for repeated measures was used to compare heart rate, cardiac output, arterial pressure, and other hemodynamic values (baseline) before and after US stimulation. Sex versus age versus US interaction was detected for heart rate. Cardiac output showed an age effect, and ejection fraction showed age and US effects. The arterial pressure showed a sex effect. A negative chronotropic effect (∼30% decrease in heart rate) was observed for young female rats. An hypothesis is that the US effect is weight (menopause) dependent, because the young (premenopausal) female rats weighed approximately 40 to 60% less than other groups of rats.

CONCLUSIONS

It is likely that the ovarian hormones are responsible for different US-induced cardiac bioeffects in different ages and sexes.

Prevalence of heart failure in Australia: a systematic review

BACKGROUND

In the absence of a systematic collection of data pertaining to heart failure, summarizing the data available from individual studies provides an opportunity to estimate the burden of heart failure. The present study systematically reviewed the literature to estimate the incidence and prevalence rates of heart failure in Australia.

METHODS

Studies reporting on prevalence or incidence of heart failure published between 1990 and 2015 were identified through a systematic search of Embase, PubMed, Ovid Medline, MeSH, Scopus and websites of the Australian Institute of Health, and Welfare and Australian Bureau of Statistics.

RESULTS

The search yielded a total of 4978 records, of which thirteen met the inclusion criteria. There were no studies reporting on the incidence of heart failure. The prevalence of heart failure in the Australian population ranged between 1.0% and 2.0%, with a significant proportion of cases being previously undiagnosed. The burden of heart failure was higher among Indigenous than non-Indigenous Australians (age-standardized prevalence rate ratio of 1.7). Heart failure was prevalent in women than men, and in rural and remote regions than in the metropolitan and capital territories.

CONCLUSION

This systematic review highlights the limited available data on the epidemiology of heart failure in Australia. Population level studies, using standardized approaches, are needed in order to precisely describe the burden of HF in the population.

Hypercholesterolemia and atherosclerosis in low density lipoprotein receptor mutant rats

To establish low density lipoprotein receptor (LDLR) mutant rats as a hypercholesterolemia and atherosclerosis model, we screened the rat LDLR gene for mutations using an N-ethyl-N-nitrosourea mutagenesis archive of rat gene data, and identified five mutations in its introns and one missense mutation (478T>A) in exon 4. The C160S mutation was located in the ligand binding domain of LDLR and was revealed to be equivalent to mutations (C160Y/G) identified in human familial hypercholesterolemia (FH) patients. The wild type, heterozygous, and homozygous mutant rats were fed a normal chow diet or a high fat high cholesterol (HFHC) diet from the age of 10 weeks for 16 weeks. The LDLR homozygous mutants fed the normal chow diet showed higher levels of plasma total cholesterol and LDL cholesterol than the wild type rats. When fed the HFHC diet, the homozygous mutant rats exhibited severe hyperlipidemia and significant lipid deposition from the aortic arch to the abdominal aorta as well as in the aortic valves. Furthermore, the female homozygous mutants also developed xanthomatosis in their paws. In conclusion, we suggest that LDLR mutant rats are a useful novel animal model of hypercholesterolemia and atherosclerosis.

Influence of sex on treatment and outcome in chronic heart failure

The population is aging, the prevalence of heart failure increases with age, and on average women live longer than men. There is evidence for sex-specific effects of individual, guideline-recommended drugs used for treatment of chronic heart failure. Women are underrepresented in most clinical trials and only a minority of drug applications to regulatory authorities have included sex analyses. The present review focuses on the potential female survival benefit in heart failure, the influence of sex on medical treatment in a broader sense, and the potential benefit to be derived from guideline recommended treatment and common adjunctive heart failure medication.

Heart failure with preserved left ventricular ejection fraction: concepts, misconceptions and future directions

Heart failure with preserved left ventricular ejection fraction (HFPEF) represents a huge medical problem, especially in light of an increasing elderly population. Dysfunction of both left ventricular filling and ejection, combined with adverse loading conditions related to advanced age, arterial hypertension, diabetes mellitus, obesity and atrial fibrillation are fundamental pathophysiological mechanisms. Hypertension is probably the most important modifiable risk factor. The diagnosis has largely been based on signs of increased left ventricular filling pressure. Additional matters of debate are the interpretation of left ventricular ejection fraction in concentric remodelling and the cut-off used for the definition of HFPEF, as well as inconsistencies related to prevalence and prognosis, and lack of benefit of drugs in randomized trials.