Activation of GPR30 attenuates diastolic dysfunction and left ventricle remodelling in oophorectomized mRen2.Lewis rats

Ovariectomy-Induced Arterial Stiffening Differs From Vascular Aging and Is Reversed by GPER Activation

BACKGROUND

Arterial stiffness is a cardiovascular risk factor and dramatically increases as women transition through menopause. The current study assessed whether a mouse model of menopause increases arterial stiffness in a similar manner to aging and whether activation of the G-protein-coupled estrogen receptor could reverse stiffness.

METHODS

Female C57Bl/6J mice were ovariectomized at 10 weeks of age or aged to 52 weeks, and some mice were treated with G-protein-coupled estrogen receptor agonists.

RESULTS

Ovariectomy and aging increased pulse wave velocity to a similar extent independent of changes in blood pressure. Aging increased carotid wall thickness, while ovariectomy increased material stiffness without altering vascular geometry. RNA-sequencing analysis revealed that ovariectomy downregulated smooth muscle contractile genes. The enantiomerically pure G-protein-coupled estrogen receptor agonist, LNS8801, reversed stiffness in ovariectomy mice to a greater degree than the racemic agonist G-1. In summary, ovariectomy and aging induced arterial stiffening via potentially different mechanisms. Aging was associated with inward remodeling, while ovariectomy-induced material stiffness independent of geometry and a loss of the contractile phenotype.

CONCLUSIONS

This study enhances our understanding of the impact of estrogen loss on vascular health in a murine model and warrants further studies to examine the ability of LNS8801 to improve vascular health in menopausal women.

Heart Failure With Preserved Ejection Fraction in the Elderly Population: Basic Mechanisms and Clinical Considerations

Heart failure with preserved ejection fraction (HFpEF) refers to a clinical condition in which the signs of heart failure, such as pulmonary congestion, peripheral edema, and increased natriuretic peptide levels, are present despite normal ejection fractions and the absence of other causes (eg, pericardial disease). The ejection fraction cutoff for the definition of HFpEF has varied in the past, but recent society guidelines have settled on a consensus of 50%. HFpEF is particularly common in the elderly population. The aim of this narrative review is to summarize the available literature regarding HFpEF in elderly patients in terms of evidence for the age dependence, specific clinical features, and underlying mechanisms. In the clinical arena, we review the epidemiology, discuss distinct clinical phenotypes typically seen in elderly patients, the importance of frailty, the role of biomarkers, and the role of medical therapies (including sodium-glucose cotransport protein 2 inhibitors, renin-angiotensin-aldosterone system blockers, angiotensin receptor/neprilysin inhibitors, diuretics, and β-adrenergic receptor blockers). We then go on to discuss the basic mechanisms implicated in HFpEF, including cellular senescence, fibrosis, inflammation, mitochondrial dysfunction, enhanced production of reactive oxygen species, abnormal cellular calcium handling, changes in microRNA signalling, insulin resistance, and sex hormone changes. Finally, we review knowledge gaps and promising areas of future investigation. Improved understanding of the specific clinical manifestations of HFpEF in elderly individuals and of the fundamental mechanisms that contribute to the age-related risk of HFpEF promises to lead to novel diagnostic and treatment approaches that will improve outcomes for this common cardiac disorder in a vulnerable population.

Association between estrogen replacement therapy and heart failure in postmenopausal women: A systematic review and meta-analysis

BACKGROUND

Based on past epidemiological investigations, the cardiovascular role of estrogen replacement therapy (ERT) in postmenopausal women has always been controversial. The real efficacy of ERT for heart failure (HF) among postmenopausal women remains to be further investigated. This article is based on research into European and American populations.

PURPOSE

To determine the impact of estrogen replacement therapy on HF using meta-analysis.

METHODS AND MATERIAL

Electronic literature was searched on Web of Science, PubMed, and Embase databases to identify randomized controlled trials (RCTs) comparing the hospitalization for heart failure between ERT users and non-users among postmenopausal women. Pairs of reviewers screened eligible articles independently, extracted data, and evaluated the risk of bias. Summary relative risks were estimated for the composite endpoint of first hospitalized heart failure and admission to the hospital for heart failure.

RESULTS

A pooled study of five randomized controlled trials found that estrogen replacement therapy had no significant effect on the composite endpoint in postmenopausal women, with a relative risk of 1.02 (95% CI 0.94-1.10).

CONCLUSION

This systematic review demonstrated that estrogen replacement therapy did not significantly change the risk of first hospitalized heart failure and admission to the hospital for heart failure in postmenopausal women.

The nongenomic neuroprotective effects of estrogen, E2-BSA, and G1 following traumatic brain injury: PI3K/Akt and histopathological study

OBJECTIVES

Studies suggest that both genomic and nongenomic pathways are involved in mediating the salutary effects of steroids following traumatic brain injury (TBI). This study investigated the nongenomic effects of 17β-estradiol (E2) mediated by the PI3K/p-Akt pathway after TBI.

METHODS

Ovariectomized rats were apportioned to E2, E2-BSA (E2 conjugated to bovine serum albumin), G1 [G-protein-coupled estrogen receptor agonist (GPER)] or their vehicle was injected following TBI, whereas ICI (classical estrogen receptor antagonist), G15 (GPER antagonist), ICI + G15, and their vehicles were injected before the induction of TBI and injection of drugs. Diffuse TBI was induced by the Marmarou model. Evans blue (EBC, 5 h), brain water contents (BWC), histopathological changes, and brain PI3K and p-Akt protein expressions were measured 24 h after TBI. The veterinary comma scale (VCS) was assessed before and at different times after TBI.

RESULTS

The results showed a reduction in BWC and EBC and increased VCS in the E2, E2-BSA, and G1 groups. Also, E2, E2-BSA, and G1 reduced brain edema, inflammation, and apoptosis. The ICI and G15 inhibited the beneficial effects of E2, E2-BSA, and G1 on these parameters. All drugs, following TBI, prevented the reduction of brain PI3K/p-Akt expression. The individual or combined use of ICI and G15 eliminated the beneficial effects of E2, E2-BSA, and G1 on PI3K/p-Akt expressions.

CONCLUSIONS

These findings indicated that PI3K/p-Akt pathway plays a critical role in mediating the salutary effects of estradiol on histopathological changes and neurological outcomes following TBI, suggesting that GPER and classic ERs are involved in regulating the expression of PI3K/p-Akt.

GPER activation attenuates cardiac dysfunction by upregulating the SIRT1/3-AMPK-UCP2 pathway in postmenopausal diabetic rats

Postmenopausal diabetic women are at higher risk to develop cardiovascular diseases (CVD) compared with nondiabetic women. Alterations in cardiac cellular metabolism caused by changes in sirtuins are one of the main causes of CVD in postmenopausal diabetic women. Several studies have demonstrated the beneficial actions of the G protein-coupled estrogen receptor (GPER) in postmenopausal diabetic CVD. However, the molecular mechanisms by which GPER has a cardioprotective effect are still not well understood. In this study, we used an ovariectomized (OVX) type-two diabetic (T2D) rat model induced by high-fat diet/streptozotocin to investigate the effect of G-1 (GPER-agonist) on sirtuins, and their downstream pathways involved in regulation of cardiac metabolism and function. Animals were divided into five groups: Sham-Control, T2D, OVX+T2D, OVX+T2D+Vehicle, and OVX+T2D+G-1. G-1 was administrated for six weeks. At the end, hemodynamic factors were measured, and protein levels of sirtuins, AMP-activated protein kinase (AMPK), and uncoupling protein 2 (UCP2) were determined by Western blot analysis. In addition, cardiac levels of oxidative stress biomarkers were measured. The findings showed that T2D led to left ventricular dysfunction and signs of oxidative stress in the myocardium, which were accompanied by decreased protein levels of Sirt1/2/3/6, p-AMPK, and UCP2 in the heart. Moreover, the induction of the menopausal state exacerbated these changes. In contrast, treatment with G-1 ameliorated the hemodynamic changes associated with ovariectomy by increasing Sirt1/3, p-AMPK, UCP2, and improving oxidative status. The results provide evidence of the cardioprotective effects of GPER operating through Sirt1/3, p-AMPK, and UCP2, thereby improving cardiac function. Our results suggest that increasing Sirt1/3 levels may offer new therapeutic approaches for postmenopausal diabetic CVD.

Icariin inhibits hypertrophy by regulation of GPER1 and CaMKII/HDAC4/MEF2C signaling crosstalk in ovariectomized mice

Icariin (ICA), a flavonoid phytoestrogen, was isolated from traditional Chinese medicine Yin Yang Huo (Epimedium brevicornu Maxim.). Previous studies reporting the cardioprotective effects of ICA are available; however, little is known about the impact of ICA on cardioprotection under conditions of reduced estrogen levels. This study aimed to provide detailed information regarding the antihypertrophic effects of ICA in ovariectomized female mice. Female mice were subjected to ovariectomy (OVX) and transverse aortic constriction and then orally treated with ICA at doses of 30, 60 or 120 mg/kg/day for 4 weeks. Morphological assessments, echocardiographic parameters, histological analyses, and immunofluorescence were performed to evaluate cardiac hypertrophy. Cardiomyocytes from mice or rats were stimulated using phenylephrine, and cell surface and hypertrophy markers were tested using immunofluorescence and qPCR. Western blotting, qPCR, and luciferase reporter gene assays were used to assess the expression of proteins and mRNA and further investigate the proteins related to the G-protein coupled estrogen receptor (GPER1) and CaMKII/HDAC4/MEF2C signaling pathways in vivo and in vitro. ICA blocks cardiac hypertrophy induced by pressure overload in OVX mice. Additionally, we demonstrated that ICA activated GPER1 and inhibited the nuclear export or promoted the nuclear import of histone deacetylase 4 (HDAC4) through regulation of phosphorylation of calmodulin-dependent protein kinase II (CaMKII) and further improved the repression of myocyte enhancer factor-2C (MEF2C). ICA ameliorated cardiac hypertrophy in OVX mice by activating GPER1 and inhibiting the CaMKII/HDAC4/MEF2 signaling pathway.

Effect of ovariohysterectomy on queen myocardial function: echocardiographic evidence

Ovariohysterectomy (OHE) is one of the most common surgeries in veterinary medicine. Although this surgical method has several advantages, it can alter the function of various organs such as heart. The present study investigated the effect of OHE on cardiac functions using M-mode echocardiography. A total of 10 healthy adult domestic short-haired cats were enrolled in the current study. Fractional shortening (FS) and ejection fraction (EF) percentages along with cardiac output (CO) were measured through the right parasternal approach in papillary muscle level view. Moreover, the levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were measured by enzyme-linked immunosorbent assay before OHE (D0) as well as 10 (D10), 20 (D20) and 30 (D30) days after OHE. The results of this study showed that the mean FS and EF decreased on all days of the study. The FS reduction was significant between D10 and D30 and EF changes were significant between D10 and D20. The means of CO increased significantly on D0 compared to the D10. After D20, CO reduced until the end of the study. Mean concentrations of LH and FSH increased on all research days; but, the changes were significant until D20. Despite the negative effects of OHE on myocardial function, there was no significant correlation between hormonal levels and echocardiographic findings after OHE in this study.

Ovariectomy-Induced Arterial Stiffening Differs from Vascular Aging and is Reversed by GPER Activation

Arterial stiffness is a cardiovascular risk factor and dramatically increases as women transition through menopause. The current study assessed whether a mouse model of menopause increases arterial stiffness in a similar manner to aging, and whether activation of the G protein-coupled estrogen receptor (GPER) could reverse stiffness. Female C57Bl/6J mice were ovariectomized (OVX) at 10 weeks of age or aged to 52 weeks, and some mice were treated with GPER agonists. OVX and aging increased pulse wave velocity to a similar extent independent of changes in blood pressure. Aging increased carotid wall thickness, while OVX increased material stiffness without altering vascular geometry. RNA-Seq analysis revealed that OVX downregulated smooth muscle contractile genes. The enantiomerically pure GPER agonist, LNS8801, reversed stiffness in OVX mice to a greater degree than the racemic agonist G-1. In summary, OVX and aging induced arterial stiffening via potentially different mechanisms. Aging was associated with inward remodeling while OVX induced material stiffness independent of geometry and a loss of the contractile phenotype. This study helps to further our understanding of the impact of menopause on vascular health and identifies LNS8801 as a potential therapy to counteract this detrimental process in women.

Estrogen-mediated mechanisms in hypertension and other cardiovascular diseases

Cardiovascular disease (CVD) is the leading cause of death globally for men and women. Premenopausal women have a lower incidence of hypertension and other cardiovascular events than men of the same age, but diminished sex differences after menopause implicates 17-beta-estradiol (E2) as a protective agent. The cardioprotective effects of E2 are mediated by nuclear estrogen receptors (ERα and ERβ) and a G protein-coupled estrogen receptor (GPER). This review summarizes both established as well as emerging estrogen-mediated mechanisms that underlie sex differences in the vasculature during hypertension and CVD. In addition, remaining knowledge gaps inherent in the association of sex differences and E2 are identified, which may guide future clinical trials and experimental studies in this field.

The G protein-coupled oestrogen receptor GPER in health and disease: an update

Oestrogens and their receptors contribute broadly to physiology and diseases. In premenopausal women, endogenous oestrogens protect against cardiovascular, metabolic and neurological diseases and are involved in hormone-sensitive cancers such as breast cancer. Oestrogens and oestrogen mimetics mediate their effects via the cytosolic and nuclear receptors oestrogen receptor-α (ERα) and oestrogen receptor-β (ERβ) and membrane subpopulations as well as the 7-transmembrane G protein-coupled oestrogen receptor (GPER). GPER, which dates back more than 450 million years in evolution, mediates both rapid signalling and transcriptional regulation. Oestrogen mimetics (such as phytooestrogens and xenooestrogens including endocrine disruptors) and licensed drugs such as selective oestrogen receptor modulators (SERMs) and downregulators (SERDs) also modulate oestrogen receptor activity in both health and disease. Following up on our previous Review of 2011, we herein summarize the progress made in the field of GPER research over the past decade. We will review molecular, cellular and pharmacological aspects of GPER signalling and function, its contribution to physiology, health and disease, and the potential of GPER to serve as a therapeutic target and prognostic indicator of numerous diseases. We also discuss the first clinical trial evaluating a GPER-selective drug and the opportunity of repurposing licensed drugs for the targeting of GPER in clinical medicine.

G Protein-Coupled Estrogen Receptor GPER: Molecular Pharmacology and Therapeutic Applications

The actions of estrogens and related estrogenic molecules are complex and multifaceted in both sexes. A wide array of natural, synthetic, and therapeutic molecules target pathways that produce and respond to estrogens. Multiple receptors promulgate these responses, including the classical estrogen receptors of the nuclear hormone receptor family (estrogen receptors α and β), which function largely as ligand-activated transcription factors, and the 7-transmembrane G protein-coupled estrogen receptor, GPER, which activates a diverse array of signaling pathways. The pharmacology and functional roles of GPER in physiology and disease reveal important roles in responses to both natural and synthetic estrogenic compounds in numerous physiological systems. These functions have implications in the treatment of myriad disease states, including cancer, cardiovascular diseases, and metabolic disorders. This review focuses on the complex pharmacology of GPER and summarizes major physiological functions of GPER and the therapeutic implications and ongoing applications of GPER-targeted compounds.

GPR30 Alleviates Pressure Overload-Induced Myocardial Hypertrophy in Ovariectomized Mice by Regulating Autophagy

The incidence of heart failure mainly resulting from cardiac hypertrophy and fibrosis increases sharply in post-menopausal women compared with men at the same age, which indicates a cardioprotective role of estrogen. Previous studies in our group have shown that the novel estrogen receptor G Protein Coupled Receptor 30 (GPR30) could attenuate myocardial fibrosis caused by ischemic heart disease. However, the role of GPR30 in myocardial hypertrophy in ovariectomized mice has not been investigated yet. In this study, female mice with bilateral ovariectomy or sham surgery underwent transverse aortic constriction (TAC) surgery. After 8 weeks, mice in the OVX + TAC group exhibited more severe myocardial hypertrophy and fibrosis than mice in the TAC group. G1, the specific agonist of GPR30, could attenuate myocardial hypertrophy and fibrosis of mice in the OVX + TAC group. Furthermore, the expression of LC3II was significantly higher in the OVX + TAC group than in the OVX + TAC + G1 group, which indicates that autophagy might play an important role in this process. An in vitro study showed that G1 alleviated AngiotensionII (AngII)-induced hypertrophy and reduced the autophagy level of H9c2 cells, as revealed by LC3II expression and tandem mRFP-GFP-LC3 fluorescence analysis. Additionally, Western blot results showed that the AKT/mTOR pathway was inhibited in the AngII group, whereas it was restored in the AngII + G1 group. To further verify the mechanism, PI3K inhibitor LY294002 or autophagy activator rapamycin was added in the AngII + G1 group, and the antihypertrophy effect of G1 on H9c2 cells was blocked by LY294002 or rapamycin. In summary, our results demonstrate that G1 can attenuate cardiac hypertrophy and fibrosis and improve the cardiac function of mice in the OVX + TAC group through AKT/mTOR mediated inhibition of autophagy. Thus, this study demonstrates a potential option for the drug treatment of pressure overload-induced cardiac hypertrophy in postmenopausal women.

Parkia speciosa Hassk. Empty Pod Extract Prevents Cardiomyocyte Hypertrophy by Inhibiting MAPK and Calcineurin-NFATC3 Signaling Pathways

Cardiac hypertrophy is an early hallmark during the clinical course of heart failure. Therapeutic strategies aiming to alleviate cardiac hypertrophy via the mitogen-activated protein kinase (MAPK)/calcineurin-nuclear factor of activated T-cells (NFAT) signaling pathway may help prevent cardiac dysfunction. Previously, empty pod ethanol crude extract of Parkia speciosa Hassk was shown to demonstrate protective effects against cardiomyocyte hypertrophy. Therefore, the current study aimed to investigate the effects of various fractions of the plant ethanol extract on the MAPK/NFAT signaling pathway in angiotensin II (Ang II)-induced cardiomyocyte hypertrophy. Simultaneous treatment with ethyl acetate (EA) fraction produced the most potent antihypertrophic effect evidenced by the reduced release of B-type natriuretic peptide (BNP). Subsequently, treatment with the EA fraction (6.25, 12.5, and 25 μg/mL) prevented an Ang II-induced increase in cell surface area, hypertrophic factors (atrial natriuretic peptide and BNP), reactive oxygen species, protein content, and NADPH oxidase 4 expression in the cells. Furthermore, EA treatment attenuated the activation of the MAPK pathway and calcineurin-related pathway (GATA-binding protein 4 and NFATC3), which was similar to the effects of valsartan (positive control). Our findings indicate that the EA fraction prevents Ang II-induced cardiac hypertrophy by regulating the MAPK/calcineurin-NFAT signaling pathway.

Sex Differences in Molecular Mechanisms of Cardiovascular Aging

Cardiovascular disease (CVD) is still the leading cause of illness and death in the Western world. Cardiovascular aging is a progressive modification occurring in cardiac and vascular morphology and physiology where increased endothelial dysfunction and arterial stiffness are observed, generally accompanied by increased systolic blood pressure and augmented pulse pressure. The effects of biological sex on cardiovascular pathophysiology have long been known. The incidence of hypertension is higher in men, and it increases in postmenopausal women. Premenopausal women are protected from CVD compared with age-matched men and this protective effect is lost with menopause, suggesting that sex-hormones influence blood pressure regulation. In parallel, the heart progressively remodels over the course of life and the pattern of cardiac remodeling also differs between the sexes. Lower autonomic tone, reduced baroreceptor response, and greater vascular function are observed in premenopausal women than men of similar age. However, postmenopausal women have stiffer arteries than their male counterparts. The biological mechanisms responsible for sex-related differences observed in cardiovascular aging are being unraveled over the last several decades. This review focuses on molecular mechanisms underlying the sex-differences of CVD in aging.

Sex Differences in Vascular Aging and Impact of GPER Deletion

Aging is a nonmodifiable risk factor for cardiovascular disease associated with arterial stiffening and endothelial dysfunction. We hypothesized that sex differences exist in vascular aging processes and would be attenuated by global deletion of the G protein-coupled estrogen receptor. Blood pressure was measured by tail cuff plethysmography, pulse wave velocity (PWV) and echocardiography were assessed with high resolution ultrasound, and small vessel reactivity was measured using wire myography in adult (25 weeks) and middle-aged (57 weeks) male and female mice. Adult female mice displayed lower blood pressure and PWV, but this sex difference was absent in middle-aged mice. Aging significantly increased PWV but not blood pressure in both sexes. Adult female carotids were more distensible than males, but this sex difference was lost during aging. Acetylcholine-induced relaxation was greater in female than male mice at both ages, and only males showed aging-induced changes in cardiac hypertrophy and function. GPER deletion removed the sex difference in PWV as well as ex vivo stiffness in adult mice. The sex difference in blood pressure was absent in KO mice and was associated with endothelial dysfunction in females. These findings indicate that the impact of aging on arterial stiffening and endothelial function is not the same in male and female mice. Moreover, nongenomic estrogen signaling through GPER impacted vascular phenotype differently in male and female mice. Delineating sex differences in vascular changes during healthy aging is an important first step in improving early detection and sex-specific treatments in our aging population.

Lipids and diastolic dysfunction: Recent evidence and findings

AIM

Diastolic dysfunction is the decreased flexibility of the left ventricle due to the impaired ability of the myocardium to relax and plays an important role in the pathogenesis of heart failure. Lipid metabolism is a well-known contributor to cardiac conditions, including ventricular function. In this article, we aimed to review the literature addressing the connections between lipids, their storage, and metabolism with left ventricular diastolic dysfunction.

DATA SYNTHESIS

We searched Google scholar, Pubmed, Embase and Researchgate for our keywords: "Diastolic function", "Fat" and "Lipid profile". Initially, 250 articles were selected by title and 84 of them were chosen as most relevant and directly reviewed.

CONCLUSIONS

Alterations of lipid metabolism in cardiac muscle and cardiac lipid content can occur in many conditions, including consumption of a high-fat diet, obesity, metabolic syndrome, and non-alcoholic fatty liver disease (NAFLD). These conditions induce alterations in myocardial lipid metabolism, increase myocardial fat content and epicardial fat thickness and increase inflammation and oxidative stress which ultimately lead to cardiac lipotoxicity and diastolic dysfunction. The effects of lipids on diastolic function can differ based on gender. Lipid profile and metabolism are as important in the pathogenesis of diastolic dysfunction as they are in other cardiovascular disorders. A more careful look at cardiac lipid metabolism in molecular, histological and gross levels results in more precise understanding of its role in myocardial function and leads to development of potential treatments for diastolic dysfunction.

Ellagic Acid Prevents Myocardial Infarction-induced Left Ventricular Diastolic Dysfunction in Ovariectomized Rats

Estrogen deficiency is associated with increased oxidative stress, which can contribute to left ventricular diastolic dysfunction (LVDD). We hypothesized that oral treatment with ellagic acid (EA), a potent and natural antioxidant compound, can improve MI-induced LVDD in ovariectomized rats, by reducing the formation of reactive oxygen species (ROS). Ovariectomized rats MI-induced LVDD followed by treatment with vehicle (DD) or EA (DD+EA) for 4 weeks. Non-LVDD-induced rats treated with vehicle (S) or EA (S+EA) were used as controls. Left ventricular systolic pressure: LVSP; left ventricular end-diastolic pressure: LVEDP; maximum rate of pressure rise: +dP/dt and fall: -dP/dt) were evaluated in all animals after treatment. Left ventricle superoxide anion formation was quantified in situ by fluorescence. Phospho-CAMKII, SOD2, catalase and gp91-phox abundances were evaluated by Western blot analyses. SOD and catalase activities were measured by spectrophotometry. The results showed that the LVEDP was significantly increased in both DD and DD+EA groups compared to S and S+EA. However, LVEDP in the DD+EA group was significantly decreased compared to DD, indicating an EA-mediated effect. In the DD group, superoxide production and gp91-phox protein abundance were increased while SOD2 abundance was decreased when compared to the S and S+EA groups. An increase in SOD activity was also observed in the DD+EA group. EA treatment reduced CaMKII phosphorylation in the DD+EA group compared to the DD. We concluded that EA treatment attenuated diastolic dysfunction in our experimental model, via reduction of ROS and CaMKII activity, indicating EA as a promising natural therapeutic option for cardiac dysfunction.

Emerging Roles for G Protein-Coupled Estrogen Receptor 1 in Cardio-Renal Health: Implications for Aging

Cardiovascular (CV) and renal diseases are increasingly prevalent in the United States and globally. CV-related mortality is the leading cause of death in the United States, while renal-related mortality is the 8th. Despite advanced therapeutics, both diseases persist, warranting continued exploration of disease mechanisms to develop novel therapeutics and advance clinical outcomes for cardio-renal health. CV and renal diseases increase with age, and there are sex differences evident in both the prevalence and progression of CV and renal disease. These age and sex differences seen in cardio-renal health implicate sex hormones as potentially important regulators to be studied. One such regulator is G protein-coupled estrogen receptor 1 (GPER1). GPER1 has been implicated in estrogen signaling and is expressed in a variety of tissues including the heart, vasculature, and kidney. GPER1 has been shown to be protective against CV and renal diseases in different experimental animal models. GPER1 actions involve multiple signaling pathways: interaction with aldosterone and endothelin-1 signaling, stimulation of the release of nitric oxide, and reduction in oxidative stress, inflammation, and immune infiltration. This review will discuss the current literature regarding GPER1 and cardio-renal health, particularly in the context of aging. Improving our understanding of GPER1-evoked mechanisms may reveal novel therapeutics aimed at improving cardio-renal health and clinical outcomes in the elderly.

G Protein-Coupled Estrogen Receptor 30 Reduces Transverse Aortic Constriction-Induced Myocardial Fibrosis in Aged Female Mice by Inhibiting the ERK1/2 -MMP-9 Signaling Pathway

The incidence of cardiovascular diseases was significantly increased in postmenopausal women. The protection of estrogen in the cardiovascular system has been further reported for decades. Although menopausal hormone therapy has been used in many clinical trials, the debatable results indicate that the studies for elucidating the precise molecular mechanism are urgently required. G protein-coupled estrogen receptor 30 (GPR30) is a membrane receptor of estrogen and displays protective roles in diverse cardiovascular diseases. Previous studies have revealed that ERK1/2-mediated MMP-9 signaling was involved in ischemic heart diseases. However, the role of ERK1/2-mediated MMP-9 signaling in the protection of GPR30 against cardiac hypertrophy in aged female mice has not been investigated. Our present study demonstrated that GPR30 overexpression and its agonist G1 co-administration reduced transverse aortic constriction-induced myocardial fibrosis and preserved cardiac function in aged female mice. MMP-9 expression was markedly increased via ERK1/2 phosphorylation in transverse aortic constriction-injured myocardium of aged female mice. Further results showed that GPR30/G1 activation decreased MMP-9 expression via ERK1/2 inhibition, which further reduced TGF-β1 expression. Inhibition of the ERK1/2 signaling pathway by its inhibitor PD98059 suppressed the induction of the cardiomyocyte MMP-9 level caused by the GRP30 antagonist G15 and inhibited TGF-β1 expression in cardiac fibroblast in vitro. In summary, our results from in vivo and in vitro studies indicated that GPR30 activation inhibited myocardial fibrosis and preserved cardiac function via inhibiting ERK-mediated MMP-9 expression. Thus, the present study may provide the novel drug targets for prevention and treatment of cardiac pathological hypertrophy in postmenopausal women.

Chronic GPER activation prevents ischemia/reperfusion injury in ovariectomized rats

During menopause women are exposed to an increase in cardiovascular risk. G protein-coupled estrogen receptor (GPER) is known to mediate several of the protective effects of such hormones. G1 was described as a selective and synthetic agonist for GPER. The aim of the present research is to evaluate the effect of a chronic treatment with G1 in ovariectomized (OVX) rats exposed to ischemia/reperfusion (I/R). Considering the hypothesis that an impaired mitochondrial state could be involved in the alterations produced in OVX rats, other objective of this study was to investigate it in an isolated preparation. Three months old rats were assigned to undergo either bilateral ovariectomy or sham operation. The OVX rats were randomly treated during one month with either G1 or vehicle. Cardiac mitochondria from OVX rats showed a depolarized membrane potential and a decreased calcium retention capacity in comparison with Sham rats, which were prevented by chronic G1 treatment. I/R caused a higher decrease of left ventricular developed pressure and a higher increase of left ventricular end diastolic pressure in OVX compared to Sham hearts. These altered mechanical parameters were prevented by G1. The induced infarct size was significantly higher in OVX, which was reduced by G1 treatment. These results indicate that the mitochondrial state in OVX rats is impaired, accompanied by an altered mechanical response after ischemia and reperfusion injury, which was effectively prevented with chronic treatment with G1. The present study may provide further insights for the potential development of a therapy based on the GPER modulation.

Chronic GPR30 agonist therapy causes restoration of normal cardiac functional performance in a male mouse model of progressive heart failure: Insights into cellular mechanisms

AIMS

G protein-coupled estrogen receptor 30 (GPR30) activation by its agonist, G1, exhibits beneficial actions in female with heart failure (HF). Recent evidence indicates its cardiovascular benefits may also include male as well. However, whether and how GPR30 activation may limit HF progression and have a salutary role in males is unknown. We hypothesized that chronic G1 treatment improves LV and cardiomyocyte function, [Ca²⁺]_i regulation and β-adrenergic reserve, thus limiting HF progression in male.

MAIN METHODS

We compared left ventricle (LV) and myocyte function, [Ca²⁺]_i transient ([Ca²⁺]_iT) and β-AR modulation in control male mice (12/group) and isoproterenol-induced HF (150 mg/kg s.c. for 2 days). Two weeks after isoproterenol injection, HF mice received placebo, or G1 (150 μg/kg/day s.c. mini-pump) for 2 weeks.

KEY FINDINGS

Isoproterenol-treated mice exhibited HF with preserved ejection fraction (HFpEF) at 2-weeks and progressed to HF with reduced EF (HFrEF) at 4-weeks, manifested by significantly increased LV time constant of relaxation (τ), decreased EF and mitral flow (dV/dt_max), which were accompanied by reduced myocyte contraction (dL/dt_max), relaxation (dR/dt_max) and [Ca²⁺]_iT. Acute isoproterenol-superfusion caused significantly smaller increases in dL/dt_max, dR/dt_max and [Ca²⁺]_iT. G1 treatment in HF increased basal and isoproterenol-stimulated increases in EF and LV contractility of E_ES. Importantly, G1 improved basal and isoproterenol-stimulated dL/dt_max, dR/dt_max and [Ca²⁺]_iT to control levels and restored normal cardiac β-AR subtypes modulation.

SIGNIFICANCE

Chronic G1 treatment restores normal myocyte basal and β-AR-stimulated contraction, relaxation, and [Ca²⁺]_iT, thereby reversing LV dysfunction and playing a rescue role in a male mouse model of HF.

Sex Differences, Estrogen Metabolism and Signaling in the Development of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a complex and devastating disease with a poor long-term prognosis. While women are at increased risk for developing PAH, they exhibit superior right heart function and higher survival rates than men. Susceptibility to disease risk in PAH has been attributed, in part, to estrogen signaling. In contrast to potential pathological influences of estrogen in patients, studies of animal models reveal estrogen demonstrates protective effects in PAH. Consistent with this latter observation, an ovariectomy in female rats appears to aggravate the condition. This discrepancy between observations from patients and animal models is often called the "estrogen paradox." Further, the tissue-specific interactions between estrogen, its metabolites and receptors in PAH and right heart function remain complex; nonetheless, these relationships are essential to characterize to better understand PAH pathophysiology and to potentially develop novel therapeutic and curative targets. In this review, we explore estrogen-mediated mechanisms that may further explain this paradox by summarizing published literature related to: (1) the synthesis and catabolism of estrogen; (2) activity and functions of the various estrogen receptors; (3) the multiple modalities of estrogen signaling in cells; and (4) the role of estrogen and its diverse metabolites on the susceptibility to, and progression of, PAH as well as their impact on right heart function.

Amplifying effect of chronic lisinopril therapy on diastolic function and the angiotensin-(1-7) Axis by the G1 agonist in ovariectomized spontaneously hypertensive rats

G protein-coupled estrogen receptor (GPER) activation by G1 attenuates diastolic dysfunction from estrogen loss, which may be partly due to suppression of angiotensin II pathological actions. We aimed to determine the independent effects of 8 weeks of G1 (100 µg/kg/d, subcutaneous pellet), ACE-inhibition (ACEi; lisinopril 10 mg/kg, drinking water), or combination therapy versus vehicle in the ovariectomized (OVX) spontaneously hypertensive rat (SHR) on cardiac function and morphometrics (echocardiography), serum equilibrium of angiotensins (mass spectroscopy) and cardiac components of the RAS (Western blotting). G1 alone and when combined with ACEi enhanced myocardial relaxation (é: 30 and 17%) and diastolic wall strain (DWS: 76 and 68%) while reducing relative wall thickness (RWT: 20 and 33%) and filling pressures (E/é: 30 and 37%). Cardiac expression levels of Mas receptor (Mas-R) and ACE2 also increased in the presence of G1. Strong antihypertensive effects of lisinopril monotherapy were associated with reductions in RWT, collagen deposition and E/é without overtly altering é or DWS. Chronic ACEi also increased cardiac levels of Mas-R and AT₁-R and tilted the circulating RAS toward the formation of Ang-(1-7), which was amplified in the presence of G1. In vitro studies further revealed that an inhibitor to prolyl endopeptidase (PEP), but not to neprilysin, significantly reduced serum Ang-(1-7) levels in G1-treated rats, suggesting that G1 might be increasing Ang-(1-7) formation via PEP. We conclude that activating GPER with G1 augments components of the cardiac RAS and improves diastolic function without lowering blood pressure, and that lisinopril-induced blood pressure control and cardiac alterations in OVX SHR are permissive in facilitating G1 to augment Ang-(1-7) in serum, thereby strengthening its cardioprotective benefits.

Sex and the G Protein-Coupled Estrogen Receptor Impact Vascular Stiffness

[Figure: see text].

G protein-coupled estrogen receptor 1: a novel target to treat cardiovascular disease in a sex-specific manner?

As an agonist of the classical nuclear receptors, estrogen receptor-α and -β (NR3A1/2), estrogen has been assumed to inhibit the development of cardiovascular disease in premenopausal women. Indeed, reduced levels of estrogen after menopause are believed to contribute to accelerated morbidity and mortality rates in women. However, estrogen replacement therapy has variable effects on cardiovascular risk in postmenopausal women, including increased serious adverse events. Interestingly, preclinical studies have shown that selective activation of the novel membrane-associated G protein-coupled estrogen receptor, GPER, can promote cardiovascular protection. These benefits are more evident in ovariectomised than intact females or in males. It is therefore possible that selective targeting of the GPER in postmenopausal women could provide cardiovascular protection with fewer adverse effects that are caused by conventional 'receptor non-specific' estrogen replacement therapy. This review describes new data regarding the merits of targeting GPER to treat cardiovascular disease with a focus on sex differences.

The Hepatoprotective mechanisms of 17β-estradiol after traumatic brain injury in male rats: Classical and non-classical estrogen receptors

Protective effects of estrogen (E2) on traumatic brain injury (TBI) have been determined. In this study, the hepatoprotective effects of E2 after TBI through its receptors and oxidative stress regulation have been evaluated. Diffuse TBI induced by the Marmarou method in male rats. G15, PHTPP, MPP, and ICI182-780 as selective antagonists of E2 were injected before TBI. The results indicated that TBI induces a significant increase in liver enzymes [Alkaline phosphatase (ALP), Aspartate aminotransferase (AST), Alanine aminotransferase (ALT), Glutamyl transferase (GGT)], and oxidants levels [Malondialdehyde (MDA), Nitric oxide (NO)] and decreases in antioxidant biomarkers [Glutathione peroxidase (GPx) and Superoxide dismutase (SOD)] in the brain and liver, and plasma. We also found that E2 significantly preserved levels of these biomarkers and enzymatic activity. All antagonists inhibited the effects of E2 on increasing SOD and GPx. Also, the effects of E2 on brain MDA levels were inhibited by all antagonists, but in the liver, only ICI + G15 + E2 + TBI group was affected. The impacts of E2 on brain and liver and plasma NO levels were inhibited by all antagonists. The current findings demonstrated that E2 probably improved liver injury after TBI by modulating oxidative stress. Also, both classic (ERβ, ERα) and non-classic [G protein-coupled estrogen receptor (GPER)] receptors are affected in the protective effects of E2.

Effects of hormone replacement therapy on left ventricular diastolic function in postmenopausal women: a systematic review and meta-analysis

BACKGROUND

Postmenopausal women tend to experience significant changes in left ventricular diastolic function (LVDF). However, there are conflicting reports about LVDF between postmenopausal women on hormone replacement therapy (HRT) and those not on HRT. This meta-analysis is to evaluate the effects of HRT on LVDF in postmenopausal women.

METHODS

We conducted a systemic review of randomized controlled trials published up to December 31 2019 using Embase, Pubmed, and the Cochrane library database.

RESULTS

Eight studies involving 668 postmenopausal women were identified. Our analysis indicated that the ratio of the peak velocity during early filing to late filling from atrial contraction improvement in HRT group was better than that in placebo group (MD 0.20, 95%CI 0.12 to 0.28). There was a significant reduction in deceleration time and left ventricular mass index in HRT group compared with placebo group (MD -21.01, 95%CI -40.11 to -1.91 vs MD -8.26, 95%CI -14.10 to -2.42). No significant difference was observed in left ventricular end systole diameter (MD 0.80, 95%CI -0.72 to 2.31), left ventricular end diastole diameter (MD -0.07, 95%CI -1.25 to 1.10), left atrial size (MD -0.33, 95%CI -1.34 to 0.68)and the isovolumic relaxation time (MD -12.08, 95%CI -27.65 to 3.5).

CONCLUSIONS

Our meta-analysis illustrated that postmenopausal women seem to obtain more beneficial effects from HRT on LVDF, though future studies are required to elucidate the specific mechanisms for this phenomenon.

Signalling mechanisms in the cardiovascular protective effects of estrogen: With a focus on rapid/membrane signalling

In modern society, cardiovascular disease remains the biggest single threat to life, being responsible for approximately one third of worldwide deaths. Male prevalence is significantly higher than that of women until after menopause, when the prevalence of CVD increases in females until it eventually exceeds that of men. Because of the coincidence of CVD prevalence increasing after menopause, the role of estrogen in the cardiovascular system has been intensively researched during the past two decades in vitro, in vivo and in observational studies. Most of these studies suggested that endogenous estrogen confers cardiovascular protective and anti-inflammatory effects. However, clinical studies of the cardioprotective effects of hormone replacement therapies (HRT) not only failed to produce proof of protective effects, but also revealed the potential harm estrogen could cause. The "critical window of hormone therapy" hypothesis affirms that the moment of its administration is essential for positive treatment outcomes, pre-menopause (3-5 years before menopause) and immediately post menopause being thought to be the most appropriate time for intervention. Since many of the cardioprotective effects of estrogen signaling are mediated by effects on the vasculature, this review aims to discuss the effects of estrogen on vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) with a focus on the role of estrogen receptors (ERα, ERβ and GPER) in triggering the more recently discovered rapid, or membrane delimited (non-genomic), signaling cascades that are vital for regulating vascular tone, preventing hypertension and other cardiovascular diseases.

Activation of G protein-coupled estrogen receptor 1 ameliorates proximal tubular injury and proteinuria in Dahl salt-sensitive female rats

Recent evidence indicates a crucial role for G protein-coupled estrogen receptor 1 (GPER1) in the maintenance of cardiovascular and kidney health in females. The current study tested whether GPER1 activation ameliorates hypertension and kidney damage in female Dahl salt-sensitive (SS) rats fed a high-salt (HS) diet. Adult female rats were implanted with telemetry transmitters for monitoring blood pressure and osmotic minipumps releasing G1 (selective GPER1 agonist, 400 μg/kg/day ip) or vehicle. Two weeks after pump implantation, rats were shifted from a normal-salt (NS) diet (0.4% NaCl) to a matched HS diet (4.0% NaCl) for 2 wk. Twenty-four hour urine samples were collected during both diet periods and urinary markers of kidney injury were assessed. Histological assessment of kidney injury was conducted after the 2-wk HS diet period. Compared with values during the NS diet, 24-h mean arterial pressure markedly increased in response to HS, reaching similar values in vehicle-treated and G1-treated rats. HS also significantly increased urinary excretion of protein, albumin, nephrin (podocyte damage marker), and KIM-1 (proximal tubule injury marker) in vehicle-treated rats. Importantly, G1 treatment prevented the HS-induced proteinuria, albuminuria, and increase in KIM-1 excretion but not nephrinuria. Histological analysis revealed that HS-induced glomerular damage did not differ between groups. However, G1 treatment preserved proximal tubule brush-border integrity in HS-fed rats. Collectively, our data suggest that GPER1 activation protects against HS-induced proteinuria and albuminuria in female Dahl SS rats by preserving proximal tubule brush-border integrity in a blood pressure-independent manner.

Sex Differences in Cardiovascular Aging and Heart Failure

PURPOSE OF THE REVIEW

This review summarizes sex-related changes in the heart and vasculature that occur with aging, both in the presence and absence of cardiovascular disease (CVD).

RECENT FINDINGS

In the presence of CVD risk factors and/or overt CVD, sex-specific changes in the number of cardiomyocytes, extent of the myocardial extracellular matrix, and myocellular hypertrophy promote unique patterns of LV remodeling in men and women. In addition, age- and sex-specific vascular stiffening is also well established, driven by changes in endothelial dysfunction, elastin-collagen content, microvascular dysfunction, and neurohormonal signaling. Together, these changes in LV chamber geometry and morphology, coupled with heightened vascular stiffness, appear to drive both age-related increases in systolic function and declines in diastolic function, particularly in postmenopausal women. Accordingly, estrogen has been implicated as a key mediator, given its direct vasodilating properties, association with nitric oxide excretion, and involvement in myocellular Ca2+ handling, mitochondrial energy production, and oxidative stress. The culmination of the abovementioned sex-specific cardiac and vascular changes across the lifespan provides important insight into heart failure development, particularly of the preserved ejection fraction variety, while offering promise for future preventive strategies and therapeutic approaches.

E2-BSA and G1 exert neuroprotective effects and improve behavioral abnormalities following traumatic brain injury: The role of classic and non-classic estrogen receptors

The role of classical and non-classical estrogen receptors (ERs) in mediating the neuroprotective effects of this hormone on brain edema and long-term behavioral disorders was evaluated after traumatic brain injury (TBI). Ovariectomized rats were divided as follows: E2 (17 β-estradiol), E2-BSA (E2 conjugated to bovine serum albumin), G1 [G-protein-coupled estrogen receptor agonist (GPER)] or their vehicle was injected following TBI, whereas ICI (classical estrogen receptor antagonist), G15 (GPER antagonist), ICI + G15, and their vehicle were injected before the induction of TBI and the injection of E2 and E2-BSA. Brain water (BWC) and Evans blue (EB) contents were measured 24 h and 5 h after TBI, respectively. Intracranial pressure (ICP) and cerebral perfusion pressure (CPP) were measured before and at different times after TBI. Locomotor activity, anxiety-like behavior, and spatial memory were assessed on days 3, 7, 14, and 21 after injury. E2, E2-BSA, and G1 prevented the increase of BWC and EB content after TBI, and these effects were inhibited by ICI and G15. ICI and G15 also inhibited the beneficial effects of E2, E2-BSA on ICP, as well as CPP, after trauma. E2, E2-BSA, and G1 prevented the cognitive deficiency and behavioral abnormalities induced by TBI. Similar to the above parameters, ICI and G15 also reversed this E2 and E2-BSA effects on days 3, 7, 14, and 21. Our findings indicated that the beneficial effects of E2-BSA and E2 were inhibited by both ICI and G15, suggesting that GPER and classic ERs were involved in mediating the long-term effects of E2.

Are there gender differences in the association between body mass index and left ventricular diastolic function? A clinical observational study in the Japanese general population

BACKGROUND

Increased body mass index (BMI) is a major risk factor for heart failure with preserved ejection fraction (HFpEF), and HFpEF is more prevalent in elderly females than males. We hypothesized that there may be gender differences in the association between BMI and echocardiographic left ventricular (LV) diastolic parameters.

METHODS

We enrolled 456 subjects (243 males) without overt cardiac diseases, all of whom underwent a health checkup. Early (E) and late (A) diastolic transmitral flow velocity, early diastolic mitral annular velocity (e'), and left atrial (LA) volume index were measured by echocardiography to assess LV diastolic function. To examine gender differences in the association between BMI and LV diastolic function, we analyzed the interaction effects of gender on the association between BMI and echocardiographic LV diastolic parameters.

RESULTS

Although there were significant gender differences in the association between BMI and E/A and e' in the crude model (interaction effect 0.037 and 0.173, respectively; P = .006 and .022, respectively), these differences were not statistically significant after adjustment for factors related to LV diastolic function. On the other hand, there were significant associations between BMI and LV diastolic parameters in each gender, even after adjustment.

CONCLUSIONS

Our findings suggest there is no gender difference in the association between BMI and echocardiographic LV diastolic parameters. However, the association between BMI and LV diastolic parameters was significant in both genders. Controlling body weight might be beneficial for both women and men to prevent progression of LV diastolic dysfunction and development of HFpEF.

G protein-coupled estrogen receptor 1 as a novel regulator of blood pressure

The mechanisms underlying hypertension are multifaceted and incompletely understood. New evidence suggests that G protein-coupled estrogen receptor 1 (GPER1) mediates protective actions within the cardiovascular and renal systems. This mini-review focuses on recent advancements in our understanding of the vascular, renal, and cardiac GPER1-mediated mechanisms that influence blood pressure regulation. We emphasize clinical and basic evidence that suggests GPER1 as a novel target to aid therapeutic strategies for hypertension. Furthermore, we discuss current controversies and challenges facing GPER1-related research.

Is Sex a Determinant of COVID-19 Infection? Truth or Myth?

Purpose of Review

Angiotensin-converting enzyme 2 (ACE2), a specific high-affinity angiotensin II-hydrolytic enzyme, is the vector that facilitates cellular entry of SARS-CoV-1 and the novel SARS-CoV-2 coronavirus. SARS-CoV-2, which crossed species barriers to infect humans, is highly contagious and associated with high lethality due to multi-organ failure, mostly in older patients with other co-morbidities.

Recent Findings

Accumulating clinical evidence demonstrates that the intensity of the infection and its complications are more prominent in men. It has been postulated that potential functional modulation of ACE2 by estrogen may explain the sex difference in morbidity and mortality.

Summary

We review here the evidence regarding the role of estrogenic hormones in ACE2 expression and regulation, with the intent of bringing to the forefront potential mechanisms that may explain sex differences in SARS-CoV-2 infection and COVID-19 outcomes, assist in management of COVID-19, and uncover new therapeutic strategies.

Sex related differences in the pathogenesis of organ fibrosis

The development of organ fibrosis has garnered rising attention as multiple diseases of increasing and/or high prevalence appear to progress to the chronic stage. Such is the case for heart, kidney, liver, and lung where diseases such as diabetes, idiopathic/autoimmune disorders, and nonalcoholic liver disease appear to notably drive the development of fibrosis. Noteworthy is that the severity of these pathologies is characteristically compounded by aging. For these reasons, research groups and drug companies have identified fibrosis as a therapeutic target for which currently, there are essentially no effective options. Although a limited body of published studies are available, most literature indicates that in multiple organs, premenopausal women are protected from developing severe forms of fibrosis suggesting an important role for sex hormones in mitigating this process. Investigators have implemented relevant animal models of organ disease linked to fibrosis supporting in general, these observations. In vitro studies and transgenic animals models have also been used in an attempt to understand the role that sex hormones and related receptors play in the development of fibrosis. However, in the setting of chronic disease in some organs such as the heart older (postmenopausal) women within a few years can quickly approach men in disease severity and develop significant degrees of fibrosis. This review summarizes the current body of relevant literature and highlights the imperative need for a major focus to be placed on understanding the manner in which sex and the presence or absence of related hormones modulates cell phenotypes so as to allow for fibrosis to develop.

Is Cardiac Diastolic Dysfunction a Part of Post-Menopausal Syndrome?

Post-menopausal women exhibit an exponential increase in the incidence of heart failure with preserved ejection fraction compared with men of the same age, which indicates a potential role of hormonal changes in subclinical and clinical diastolic dysfunction. This paper reviews the preclinical evidence that demonstrates the involvement of estrogen in many regulatory molecular pathways of cardiac diastolic function and the clinical data that investigates the effect of estrogen on diastolic function in post-menopausal women. Published reports show that estrogen deficiency influences both early diastolic relaxation via calcium homeostasis and the late diastolic compliance associated with cardiac hypertrophy and fibrosis. Because of the high risk of diastolic dysfunction and heart failure with preserved ejection fraction in post-menopausal women and the positive effects of estrogen on preserving cardiac function, further clinical studies are needed to clarify the role of endogenous estrogen or hormone replacement in mitigating the onset and progression of heart failure with preserved ejection fraction in women.

The Role of Estrogen Receptors in Cardiovascular Disease

Cardiovascular Diseases (CVDs) are the leading cause of death globally. More than 17 million people die worldwide from CVD per year. There is considerable evidence suggesting that estrogen modulates cardiovascular physiology and function in both health and disease, and that it could potentially serve as a cardioprotective agent. The effects of estrogen on cardiovascular function are mediated by nuclear and membrane estrogen receptors (ERs), including estrogen receptor alpha (ERα), estrogen receptor beta (ERβ), and G-protein-coupled ER (GPR30 or GPER). Receptor binding in turn confers pleiotropic effects through both genomic and non-genomic signaling to maintain cardiovascular homeostasis. Each ER has been implicated in multiple pre-clinical cardiovascular disease models. This review will discuss current reports on the underlying molecular mechanisms of the ERs in regulating vascular pathology, with a special emphasis on hypertension, pulmonary hypertension, and atherosclerosis, as well as in regulating cardiac pathology, with a particular emphasis on ischemia/reperfusion injury, heart failure with reduced ejection fraction, and heart failure with preserved ejection fraction.

Cardiac tissue remodeling in healthy aging: the road to pathology

This review aims to highlight the normal physiological remodeling that occurs in healthy aging hearts, including changes that occur in contractility, conduction, valve function, large and small coronary vessels, and the extracellular matrix. These "normal" age-related changes serve as the foundation that supports decreased plasticity and limited ability for tissue remodeling during pathophysiological states such as myocardial ischemia and heart failure. This review will identify populations at greater risk for poor tissue remodeling in advanced age along with present and future therapeutic strategies that may ameliorate dysfunctional tissue remodeling in aging hearts.

2-Methoxyestradiol Attenuates Angiotensin II-Induced Hypertension, Cardiovascular Remodeling, and Renal Injury

Estradiol may antagonize the adverse cardiovascular effects of angiotensin II (Ang II). We investigated the effects of 2-methoxyestradiol (2-ME), a nonestrogenic estradiol metabolite, on Ang II-induced cardiovascular and renal injury in male rats. First, we determined the effects of 2-ME on Ang II-induced acute changes in blood pressure, renal hemodynamics, and excretory function. Next, we investigated the effects of 2-ME and 2-hydroxyestardiol (2-HE) on hypertension and cardiovascular and renal injury induced by chronic infusion of Ang II. Furthermore, the effects of 2-ME on blood pressure and cardiovascular remodeling in the constricted aorta (CA) rat model and on isoproterenol-induced (ISO) cardiac hypertrophy and fibrosis were examined. 2-ME had no effects on Ang II-induced acute changes in blood pressure, renal hemodynamics, or glomerular filtration rate. Both 2-ME and 2-HE reduced hypertension, cardiac hypertrophy, proteinuria, and mesangial expansion induced by chronic Ang II infusions. In CA rats, 2-ME attenuated cardiac hypertrophy and fibrosis and reduced elevated blood pressure above the constriction. Notably, 2-ME reduced both pressure-dependent (above constriction) and pressure-independent (below constriction) vascular remodeling. 2-ME had no effects on ISO-induced renin release yet reduced ISO-induced cardiac hypertrophy and fibrosis. This study shows that 2-ME protects against cardiovascular and renal injury due to chronic activation of the renin-angiotensin system. This study reports for the first time that in vivo 2-ME reduces trophic (pressure-independent) effects of Ang II and related cardiac and vascular remodeling.

The role of inflammation in driving left ventricular remodeling in a pre-HFpEF model

IMPACT STATEMENT

The incidence of HFpEF continues to increase and ∼2/3 of the patient population are post-menopausal women. Unfortunately, most studies focus on the use of male animal models of remodeling. In this study, however, using female rats to set a model of pre-HFpEF, we provide insights to possible mechanisms that contribute to HFpEF development in humans that will lead us to a better understanding of the underlying pathophysiology of HFpEF.

Non-ischemic dilated cardiomyopathy and cardiac fibrosis

Cardiac fibrosis is associated with non-ischemic dilated cardiomyopathy, increasing its morbidity and mortality. Cardiac fibroblast is the keystone of fibrogenesis, being activated by numerous cellular and humoral factors. Macrophages, CD4+ and CD8+ T cells, mast cells, and endothelial cells stimulate fibrogenesis directly by activating cardiac fibroblasts and indirectly by synthetizing various profibrotic molecules. The synthesis of type 1 and type 3 collagen, fibronectin, and α-smooth muscle actin is rendered by various mechanisms like transforming growth factor-beta/small mothers against decapentaplegic pathway, renin angiotensin system, and estrogens, which in turn alter the extracellular matrix. Investigating the underlying mechanisms will allow the development of diagnostic and prognostic tools and discover novel specific therapies. Serum biomarkers aid in the diagnosis and tracking of cardiac fibrosis progression. The diagnostic gold standard is cardiac magnetic resonance with gadolinium administration that allows quantification of cardiac fibrosis either by late gadolinium enhancement assessment or by T1 mapping. Therefore, the goal is to stop and even reverse cardiac fibrosis by developing specific therapies that directly target fibrogenesis, in addition to the drugs used to treat heart failure. Cardiac resynchronization therapy had shown to revert myocardial remodeling and to reduce cardiac fibrosis. The purpose of this review is to provide an overview of currently available data.

Estradiol Treatment Initiated Early After Ovariectomy Regulates Myocardial Gene Expression and Inhibits Diastolic Dysfunction in Female Cynomolgus Monkeys: Potential Roles for Calcium Homeostasis and Extracellular Matrix Remodeling

Background

Left ventricular (LV) diastolic dysfunction often precedes heart failure with preserved ejection fraction, the dominant form of heart failure in postmenopausal women. The objective of this study was to determine the effect of oral estradiol treatment initiated early after ovariectomy on LV function and myocardial gene expression in female cynomolgus macaques.

Methods and Results

Monkeys were ovariectomized and randomized to receive placebo (control) or oral estradiol at a human‐equivalent dose of 1 mg/day for 8 months. Monkeys then underwent conventional and tissue Doppler imaging to assess cardiac function, followed by transcriptomic and histomorphometric analyses of LV myocardium. Age, body weight, blood pressure, and heart rate were similar between groups. Echocardiographic mitral early and late inflow velocities, mitral annular velocities, and mitral E deceleration slope were higher in estradiol monkeys (all P<0.05), despite similar estimated LV filling pressure. MCP1 (monocyte chemoattractant protein 1) and LV collagen staining were lower in estradiol animals (P<0.05). Microarray analysis revealed differential myocardial expression of 40 genes (>1.2‐fold change; false discovery rate, P<0.05) in estradiol animals relative to controls, which implicated pathways associated with better calcium ion homeostasis and muscle contraction and lower extracellular matrix deposition (P<0.05).

Conclusions

Estradiol treatment initiated soon after ovariectomy resulted in enhanced LV diastolic function, and altered myocardial gene expression towards decreased extracellular matrix deposition, improved myocardial contraction, and calcium homeostasis, suggesting that estradiol directly or indirectly modulates the myocardial transcriptome to preserve cardiovascular function.

A Selective Ligand for Estrogen Receptor Proteins Discriminates Rapid and Genomic Signaling

Estrogen exerts extensive and diverse effects throughout the body of women. In addition to the classical nuclear estrogen receptors (ERα and ERβ), the G protein-coupled estrogen receptor GPER is an important mediator of estrogen action. Existing ER-targeted therapeutic agents act as GPER agonists. Here, we report the identification of a small molecule, named AB-1, with the previously unidentified activity of high selectivity for binding classical ERs over GPER. AB-1 also possesses a unique functional activity profile as an agonist of transcriptional activity but an antagonist of rapid signaling through ERα. Our results define a class of small molecules that discriminate between the classical ERs and GPER, as well as between modes of signaling within the classical ERs. Such an activity profile, if developed into an ER antagonist, could represent an opportunity for the development of first-in-class nuclear hormone receptor-targeted therapeutics for breast cancer exhibiting reduced acquired and de novo resistance.

Cardioprotection Induced by Activation of GPER in Ovariectomized Rats With Pulmonary Hypertension

Pulmonary hypertension (PH) is a disease of women (female-to-male ratio 4:1), and is associated with cardiac and skeletal muscle dysfunction. Herein, the activation of a new estrogen receptor (GPER) by the agonist G1 was evaluated in oophorectomized rats with monocrotaline (MCT)-induced PH. Depletion of estrogen was induced by bilateral oophorectomy (OVX) in Wistar rats. Experimental groups included SHAM or OVX rats that received a single intraperitoneal injection of MCT (60 mg/kg) for PH induction. Animals received s.c. injection of either vehicle or G1, a GPER agonist, (400 µg/kg/day) for 14 days after the onset of disease. Rats with PH exhibited exercise intolerance and cardiopulmonary alterations, including reduced pulmonary artery flow, biventricular remodeling, and left ventricular systolic and diastolic dysfunction. The magnitude of these PH-induced changes was significantly greater in OVX versus SHAM rats. G1 treatment reversed both cardiac and skeletal muscle functional aberrations caused by PH in OVX rats. G1 reversed PH-related cardiopulmonary dysfunction and exercise intolerance in female rats, a finding that may have important implications for the ongoing clinical evaluation of new drugs for the treatment of the disease in females after the loss of endogenous estrogens.

Connecting sex differences, estrogen signaling, and microRNAs in cardiac fibrosis

Sex differences are evident in the pathophysiology of heart failure (HF). Progression of HF is promoted by cardiac fibrosis and no fibrosis-specific therapies are currently available. The fibrotic response is mediated by cardiac fibroblasts (CFs), and a central event is their phenotypic transition to pro-fibrotic myofibroblasts. These myofibroblasts may arise from various cellular origins including resident CFs and epicardial and endothelial cells. Both female subjects in clinical studies and female animals in experimental studies generally present less cardiac fibrosis compared with males. This difference is at least partially considered attributable to the ovarian hormone 17β-estradiol (E2). E2 signals via estrogen receptors to regulate genes are involved in the fibrotic response and myofibroblast transition. Besides protein-coding genes, E2 also regulates transcription of microRNA that modulate cardiac fibrosis. Sex dimorphism, E2, and miRNAs form multi-level regulatory networks in the pathophysiology of cardiac fibrosis, and the mechanism of these networks is not yet fully deciphered. Therefore, this review is aimed at summarizing current knowledge on sex differences, E2, and estrogen receptors in cardiac fibrosis, emphasizing on microRNAs and myofibroblast origins. KEY MESSAGES: • E2 and ERs regulate cardiac fibroblast function. • E2 and ERs may distinctly affect male and female cardiac fibrosis pathophysiology. • Sex, E2, and miRNAs form multi-level regulatory networks in cardiac fibrosis. • Sex-dimorphic and E2-regulated miRNAs affect mesenchymal transition.

NLRP3 inhibition improves heart function in GPER knockout mice

The molecular mechanisms of postmenopausal heart diseases in women may involve the loss of estrogen-deactivation of its membrane receptor, G-protein coupled estrogen receptor (GPER), and subsequent activation of the cardiac NLRP3 inflammasome, a component of the innate immune system. To study the potential effects of cardiac GPER on NLRP3-mediated inflammatory pathways, we characterized changes in innate immunity gene transcripts in hearts from 6-month-old cardiomyocyte-specific GPER knockout (KO) mice and their GPER-intact wild type (WT) littermates using RT² Profiler™ real-time PCR array. GPER deletion in cardiomyocytes decreased %fractional shortening (%FS) and myocardial relaxation (e'), and increased the early mitral inflow filling velocity-to-early mitral annular descent velocity ratio (E/e'), determined by echocardiography, and increased the mRNA levels of atrial natriuretic factor (ANF) and brain natriuretic peptide (BNP), determined by real-time PCR. Of the 84 inflammasome-related genes tested, 9 genes were upregulated, including NLRP3 and IL-18, while 1 gene, IL-12a, was downregulated in GPER KO when compared to WT. The importance of NLRP3 upregulation in GPER KO-induced heart failure was further confirmed by an in vivo study showing that, compared to vehicle-treated KO mice, 8 weeks of treatment with a NLRP3 inhibitor, MCC950 (10 mg/kg, i.p., 3 times per week), significantly limited hypertrophic remodeling, defined by reductions in heart weight/body weight, and improved systolic and diastolic functional indices, including increases in %FS and e', and decreases E/e' (P < 0.05). Both ANF and BNP mRNA levels were also significantly reduced by chronic MCC950 treatment. The findings from this study point toward a new understanding for the increased occurrence of heart diseases in women following loss or absence of estrogenic protection and GPER activation that involves cardiac NLRP3 inflammatory pathways.