Dose-dependent cardiac effect of oestrogen replacement in mice post-myocardial infarction

Regulation of cardiac fibroblasts by lymphocytes after a myocardial infarction: playing in the major league

Cardiac fibrosis is a pathological condition characterized by excessive accumulation of extracellular matrix components within the myocardium, which can lead to impaired cardiac function and heart failure. Studies have shown that lymphocytes including B and T cells play important roles in the development and progression of cardiac fibrosis after a myocardial infarction. In this review, we focus on the regulation of cardiac fibrosis by lymphocyte subsets, with a particular emphasis on CD4+ and CD8+ T cells and their effects on fibroblasts and cardiac remodeling. We also highlight areas for further exploration of the interactions between T cells and fibroblasts necessary for understanding and treating cardiac fibrosis and heart failure.

Estrogen is required for maintaining the quality of cardiac stem cells

Compared to the age-matched men, the incidence of cardiovascular diseases is lower in premenopausal but higher in postmenopausal women, suggesting the cardio-protective role of estrogen in females. Although cardiac stem cells (CSCs) express estrogen receptors, yet the effects of estrogen on CSCs remain unclear. In this study, we investigated the potential role of estrogen in maintaining the quality of CSCs by in vivo and in vitro experiments. For the in vivo study, estrogen deficiency was induced by ovariectomy in 6-weeks-old C57BL/6 female mice, and then randomly given 17β-estradiol (E₂) replacements at a low dose (0.01 mg/60 days) and high dose (0.18 mg/60 days), or vehicle treatment. All mice were killed 2 months after treatments, and heart tissues were collected for ex vivo expansion of CSCs. Compared to age-matched healthy controls, estrogen deficiency slightly decreased the yield of CSCs with significantly lower telomerase activity and more DNA damage. Interestingly, E₂ replacements at low and high doses significantly increased the yield of CSCs and reversed the quality impairment of CSCs following estrogen deficiency. For the in vitro study, twice-passaged CSCs from the hearts of adult healthy female mice were cultured with the supplement of 0.01, 0.1, and 1 μM E₂ in the medium for 3 days. We found that E₂ supplement increased c-kit expression, increased proliferative activity, improved telomerase activity, and reduced DNA damage of CSCs in a dose-dependent manner. Our data suggested the potential role of estrogen in maintaining the quality of CSCs, providing new insight into the cardio-protective effects of estrogen.

PCSK9 inhibitor and atorvastatin reduce cardiac impairment in ovariectomized prediabetic rats via improved mitochondrial function and Ca2+ regulation

Post‐menopausal women have a higher risk of developing cardiometabolic dysfunction. Atorvastatin attenuates dyslipidaemia and cardiac dysfunction but it can have undesirable effects including increased risk of diabetes and myalgia. Currently, the proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitor efficiently reduces low‐density lipoprotein cholesterol (LDL‐C) levels more effectively than atorvastatin. We have been suggested that PCSK9 inhibitor attenuated cardiometabolic impairment more effectively than atorvastatin in ovariectomized prediabetic rats. Female Wistar rats (n = 48) were fed a normal diet (ND) or high‐fat diet (HFD) for 12 weeks. Then, HFD rats were assigned to a sham‐operated (Sham) or ovariectomized (OVX) group. Six weeks after surgery, the OVX group was subdivided into 4 treatment groups: vehicle (HFOV), atorvastatin (HFOA) (40 mg/kg/day; s.c.), PCSK9 inhibitor (HFOP) (4 mg/kg/day; s.c.) and oestrogen (HFOE₂) (50 µg/kg/day; s.c.) for an additional 3 weeks. Metabolic parameters, cardiac and mitochondrial function, and [Ca²⁺]_i transients were evaluated. All HFD rats became obese‐insulin resistant. HFS rats had significantly impaired left ventricular (LV) function, cardiac mitochondrial function and [Ca²⁺]_i transient dysregulation. Oestrogen deprivation (HFOV) aggravated all of these impairments. Our findings indicated that the atorvastatin, PCSK9 inhibitor and oestrogen shared similar efficacy in the attenuation in cardiometabolic impairment in ovariectomized prediabetic rats.

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

Aims

Sex differences in cardiac fibrosis point to the regulatory role of 17β-Estradiol (E2) in cardiac fibroblasts (CF). We, therefore, asked whether male and female CF in rodent and human models are differentially susceptible to E2, and whether this is related to sex-specific activation of estrogen receptor alpha (ERα) and beta (ERβ).

Methods and results

In female rat CF (rCF), 24 h E2-treatment (10-8  M) led to a significant down-regulation of collagen I and III expression, whereas both collagens were up-regulated in male rCF. E2-induced sex-specific collagen regulation was also detected in human CF, indicating that this regulation is conserved across species. Using specific ERα- and ERβ-agonists (10-7 M) for 24 h, we identified ERα as repressive and ERβ as inducing factor in female and male rCF, respectively. In addition, E2-induced ERα phosphorylation at Ser118 only in female rCF, whereas Ser105 phosphorylation of ERβ was exclusively found in male rCF. Further, in female rCF we found both ER bound to the collagen I and III promoters using chromatin immunoprecipitation assays. In contrast, in male rCF only ERβ bound to both promoters. In engineered connective tissues (ECT) from rCF, collagen I and III mRNA were down-regulated in female ECT and up-regulated in male ECT by E2. This was accompanied by an impaired condensation of female ECT, whereas male ECT showed an increased condensation and stiffness upon E2-treatment, analysed by rheological measurements. Finally, we confirmed the E2-effect on both collagens in an in vivo mouse model with ovariectomy for E2 depletion, E2 substitution, and pressure overload by transverse aortic constriction.

Conclusion

The mechanism underlying the sex-specific regulation of collagen I and III in the heart appears to involve E2-mediated differential ERα and ERβ signaling in CFs.

Left ventricular remodelling after ST-segment elevation myocardial infarction: sex differences and prognosis

Aims

Left ventricular (LV) remodelling after ST‐segment elevation myocardial infarction (STEMI) worsens outcome. The effect of sex on LV post‐infarct remodelling is unknown. We therefore investigated the sex distribution and long‐term prognosis of LV post‐infarct remodelling after STEMI in the contemporary era of primary percutaneous coronary intervention (PCI) and optimal pharmacotherapy.

Methods and results

Data were obtained from an ongoing primary PCI STEMI registry. LV remodelling was defined as ≥20% increase in LV end‐diastolic volume at either 3, 6, or 12 months post‐infarct, and LV remodelling impact on outcome was evaluated with a log‐rank test. A total population of 1995 STEMI patients were analysed (mean age 60 ± 12 years): 1527 (77%) men and 468 (23%) women. The mean age of male patients was 60±11 versus 63±13 years for women (P < 0.001). A total of 953 (48%) patients experienced LV remodelling in the first 12 months of follow‐up, and it was equally frequent amongst men (n = 729, 48%) and women (n = 224, 48%). After a median follow‐up of 94 (interquartile range 69–119) months, 225 patients died: 171 (11%) men and 54 (12%) women. No survival difference was seen between remodellers and non‐remodellers in the male (P = 0.113) and female (P = 0.920) groups.

Conclusion

LV post‐infarct remodelling incidence, as well as long‐term survival of LV remodellers and non‐remodellers, was similar in men and women who were treated with primary PCI and optimal pharmacotherapy post‐STEMI.

Somewhere over the sex differences rainbow of myocardial infarction remodeling: hormones, chromosomes, inflammasome, oh my

Introduction: Cardiovascular disease is a major cause of death in both men and women. While women are protected until the onset of menopause, after menopause women have increased risk of adverse cardiovascular disease events. Animal models of myocardial infarction recapitulate many of the sex differences observed in humans, and proteomics evaluations offer mechanistic insights to explain sex differences.Areas covered: In this review, we will discuss how proteomics has helped us understand the hormonal, chromosomal, and immune mechanisms behind sex differences in response to ischemic injury and the development of heart failure.Expert opinion: There are a number of ways in which proteomics has and will continue to facilitate our understanding of sex differences in cardiac remodeling after myocardial infarction.

Estrogen Therapy Worsens Cardiac Function and Remodeling and Reverses the Effects of Exercise Training After Myocardial Infarction in Ovariectomized Female Rats

There is an increase in the incidence of cardiovascular events such as myocardial infarction (MI) after menopause. However, the use of estrogen therapy (E2) remains controversial. The aim of this study was to evaluate the effects of E2, alone and combined with exercise training (ET), on cardiac function and remodeling in ovariectomized (OVX) rats after MI. Wistar female rats underwent ovariectomy, followed by MI induction were separated into five groups: S; MI; MI+ET; MI+E2; and MI+ET+E2. Fifteen days after MI or sham surgery, treadmill ET and/or estrogen therapy [17-β estradiol-3-benzoate (E2), s.c. three times/week] were initiated and maintained for 8 weeks. After the treatment and/or training period, the animals underwent cardiac hemodynamic evaluation through catheterization of the left ventricle (LV); the LV systolic and diastolic pressures (LVSP and LVEDP, respectively), maximum LV contraction and relaxation derivatives (dP/dt+ and dP/dt−), and isovolumic relaxation time (Tau) were assessed. Moreover, histological analyses of the heart (collagen and hypertrophy), cardiac oxidative stress [advanced oxidation protein products (AOPPs)], pro- and antioxidant protein expression by Western blotting and antioxidant enzyme activity in the heart were evaluated. The MI reduced the LVSP, dP/dt+ and dP/dt− but increased the LVEDP and Tau. E2 did not prevent the MI-induced changes in cardiac function, even when combined with ET. An increase in the dP/dt+ was observed in the E2 group compared with the MI group. There were no changes in collagen deposition and myocyte hypertrophy caused by the treatments. The increases in AOPP, gp91-phox, and angiotensin II type 1 receptor expression induced by MI were not reduced by E2. There were no changes in the expression of catalase caused by MI or by the treatments, although, a reduction in superoxide dismutase (SOD) expression occurred in the groups subjected to E2 treatment. Whereas there were post-MI reductions in activities of SOD and catalase enzymes, only that of SOD was prevented by ET. Therefore, we conclude that E2 therapy does not prevent the MI-induced changes in cardiac function and worsens parameters related to cardiac remodeling. Moreover, E2 reverses the positive effects of ET when used in combination, in OVX infarcted female rats.

Both GPER and membrane oestrogen receptor-α activation protect ventricular remodelling in 17β oestradiol-treated ovariectomized infarcted rats

Clinical and experimental studies have established that gender is a factor in the development of ventricular hypertrophy. We investigated whether the attenuated hypertrophic effect of oestradiol was via activation of phosphatidylinositol 3-kinase (PI3K)/Akt/endothelial nitric oxide synthase (eNOS) through non-genomic action. Twenty-four hours after coronary ligation, female Wistar rats were randomized into control, subcutaneous oestradiol treatment or a G-protein coupled oestrogen receptor (GPER) agonist, G-1 and treated for 4 weeks starting from 2 weeks after bilateral ovariectomy. Ventricular hypertrophy assessed by cardiomyocyte size after infarction was similarly attenuated by oestradiol or G-1 in infarcted rats. The phosphorylation of Akt and eNOS was significantly decreased in infarcted rats and restored by oestradiol and G-1, implying the GPER pathway in this process. Oestradiol-induced Akt phosphorylation was not abrogated by G-15 (a GPER blocker). Akt activation was not inhibited by actinomycin D. When a membrane-impermeable oestrogen-albumin construct was applied, similar responses in terms of eNOS activation to those of oestradiol were achieved. Furthermore, PPT, an ERα receptor agonist, activated the phosphorylation of Akt and eNOS. Thus, membrane ERα receptor played a role in mediating the phosphorylation of Akt and eNOS. The specific PI3K inhibitor, LY290042, completely abolished Akt activation and eNOS phosphorylation in infarcted hearts treated with either oestradiol or oestradiol + G-15. These data support the conclusions that oestradiol improves ventricular remodelling by both GPER- and membrane-bound ERα-dependent mechanisms that converge into the PI3K/Akt/eNOS pathway, unveiling a novel mechanism by which oestradiol regulates pathological cardiomyocyte growth after infarction.

Gender differences in adenine-induced chronic kidney disease and cardiovascular complications in rats

Gender contributes to differences in incidence and progression of chronic kidney disease (CKD) and associated cardiovascular disease. To induce kidney damage in male and female Wistar rats (n = 12/group), a 0.25% adenine diet for 16 wk was used. Kidney function (blood urea nitrogen, plasma creatinine, proteinuria) and structure (glomerular damage, tubulointerstitial atrophy, fibrosis, inflammation); cardiovascular function (blood pressure, ventricular stiffness, vascular responses, echocardiography) and structure (cardiac fibrosis); plasma testosterone and estrogen concentrations; and protein expression for oxidative stress [heme oxygenase-1, inflammation (TNF-α), fibrosis (transforming growth factor-β), ERK1/2, and estrogen receptor-α (ER-α)] were compared in males and females. Adenine-fed females had less decline in kidney function than adenine-fed males, although kidney atrophy, inflammation, and fibrosis were similar. Plasma estrogen concentrations increased and plasma testosterone concentrations decreased in adenine-fed males, with smaller changes in females. CKD-associated molecular changes in kidneys were more pronounced in males than females except for expression of ER-α in the kidney, which was completely suppressed in adenine-fed males but unchanged in adenine-fed females. Both genders showed increased blood pressure, ventricular stiffness, and cardiac fibrosis with the adenine diet. Cardiovascular changes with adenine were similar in males and females, except males developed concentric, and females eccentric cardiac hypertrophy. In hearts from adenine-fed male and female rats, expression of ER-α and activation of the ERK1/2 pathway were increased, in part explaining changes in cardiac hypertrophy. In summary, adenine-induced kidney damage may be increased in males due to the suppression of ER-α.

Menopausal hormone therapy: examining cardiovascular and clinical impacts of treatment

Postmenopausal women have reduced levels of female sex hormones and this may play a significant role in the onset of cardiovascular disease. Menopausal hormone therapy (MHT), which is primarily prescribed for the treatment of perimenopausal symptoms, has been associated with risk of coronary heart disease, hypertension and stroke in women. This review will summarize the outcomes of observational studies and randomized clinical trials that have investigated the influence of MHT use on the cardiovascular system. In addition, it will explore how the timing of MHT prescription relative to menopause, dosage and route of administration may alter the impact of MHT on cardiovascular health.

Sex and sex hormones in cardiac stress--mechanistic insights

Important sex differences in the onset and characteristics of cardiovascular disease are evident, yet the mechanistic details remain unresolved. Men are more susceptible to cardiovascular disease earlier in life, though younger women who have a cardiovascular event are more likely to experience adverse outcomes. Emerging evidence is prompting a re-examination of the conventional view that estrogen is protective and testosterone a liability. The heart expresses both androgen and estrogen receptors and is functionally responsive to circulating sex steroids. New evidence of cardiac aromatase expression indicates local estrogen production may also exert autocrine/paracrine actions in the heart. Cardiomyocyte contractility studies suggest testosterone and estrogen have contrasting inotropic actions, and modulate Ca(2+) handling and transient characteristics. Experimentally, sex differences are also evident in cardiac stress responses. Female hearts are generally less susceptible to acute ischemic damage and associated arrhythmias, and generally are more resistant to stress-induced hypertrophy and heart failure, attributed to the cardioprotective actions of estrogen. However, more recent data show that testosterone can also improve acute post-ischemic outcomes and facilitate myocardial function and survival in chronic post-infarction. The myocardial actions of sex steroids are complex and context dependent. A greater mechanistic understanding of the specific actions of systemic/local sex steroids in different cardiovascular disease states has potential to lead to the development of cardiac therapies targeted specifically for men and women.

Sexual dimorphism in rodent models of hypertension and atherosclerosis

Approximately one third of all deaths are attributed to cardiovascular disease (CVD), making it the biggest killer worldwide. Despite a number of therapeutic options available, the burden of CVD morbidity continues to grow indicating the need for continued research to address this unmet need. In this respect, investigation of the mechanisms underlying the protection that premenopausal females enjoy from cardiovascular-related disease and mortality is of interest. In this review, we discuss the essential role that rodent animal models play in enabling this field of research. In particular, we focus our discussion on models of hypertension and atherosclerosis.

Protective role of AT(2) and B(1) receptors in kinin B(2)-receptor-knockout mice with myocardial infarction

AT(2)Rs [AngII (angiotensin II) type 2 receptors] contribute to the cardioprotective effects of angiotensin II receptor blockers, possibly via kinins acting on the B(1)R (B(1) receptor) and B(2)R (B(2) receptor). Recent studies have shown that a lack of B(2)R up-regulates B(1)R and AT(2)R; however, the pathophysiological relevance of such an event remains unclear. We hypothesized that up-regulation of AT(2)R and B(1)R compensates for the loss of B(2)R. Blockade of AT(2)R and/or B(1)R worsens cardiac remodelling and dysfunction following MI (myocardial infarction) in B(2)R(-/-) (B(2)-receptor-knockout mice). B(2)R(-/-) mice and WT (wild-type) controls were subjected to sham MI or MI and treated for 4 weeks with (i) vehicle, (ii) a B(1)R-ant (B(1)R antagonist; 300 μg/kg of body weight per day), (iii) an AT(2)R-ant [AT(2) receptor antagonist (PD123319); 20 mg/kg of body weight per day], or (iv) B(1)R-ant+AT(2)R-ant. B(2)R(-/-) mice had a greater MCSA (myocyte cross-sectional area) and ICF (interstitial collagen fraction) at baseline and after MI compared with WT controls. Cardiac function and increase in macrophage infiltration, TGFβ(1) (transforming growth factor β(1)) expression and ERK1/2 (extracellular-signal-regulated kinase 1/2) phosphorylation post-MI were similar in both strains. Blockade of AT(2)R or B(1)R worsened cardiac remodelling, hypertrophy and dysfunction associated with increased inflammation and ERK1/2 phosphorylation and decreased NO excretion in B(2)R(-/-) mice, which were exacerbated by dual blockade of B(1)R and AT(2)R. No such effects were seen in WT mice. Our results suggest that, in the absence of B(2)R, both B(1)R and AT(2)R play important compensatory roles in preventing deterioration of cardiac function and remodelling post-MI possibly via suppression of inflammation, TGFβ(1) and ERK1/2 signalling.

Feminizing adrenal carcinoma presenting with heart failure and ventricular tachycardia

We present a case of feminizing adrenal carcinoma with severe elevation in serum estradiol and otherwise unexplained congestive heart failure with ventricular arrhythmia and review the literature on feminizing adrenal tumors and the potential relationship between estrogen and cardiac problems. A 54-year-old man presented with congestive heart failure and ventricular arrhythmia. Imaging revealed a large adrenal mass. Hormonal evaluation revealed a very high serum level of estradiol, elevated DHEA-sulfate and androstenedione, and lack of cortisol suppression on a low-dose overnight dexamethasone suppression test. The patient underwent a left adrenalectomy with subsequent normalization of serum estradiol. Surgical pathology examination established adrenocortical carcinoma MacFarlane stage II. Upon 15-month followup, the patient continued to have a normal serum estradiol level, his cardiac function was significantly improved, and he had no further episodes of ventricular arrhythmia. To the best of our knowledge, the serum estradiol level that was detected in our case is the highest that has been reported. Further, we hypothesize that the very high serum concentration of estradiol in our case may have played a role in his cardiac presentation with congestive heart failure and arrhythmia, particularly as these problems resolved with normalization of his serum estradiol level.

Effects of estrogen on cardiovascular injury in ovariectomized female DahlS.Z-Lepr(fa)/Lepr(fa) rats as a new animal model of metabolic syndrome

Although recent clinical trials have found an increased incidence of cardiovascular disease in women on estrogen replacement therapy, the underlying mechanism remains unclear. We have recently characterized DahlS.Z-Lepr(fa)/Lepr(fa) (DS/obese) rats, derived from a cross between Dahl salt-sensitive and Zucker rats, as a new animal model of metabolic syndrome. We have now examined the effects of estrogen replacement on cardiac pathophysiology in ovariectomized female DS/obese (Ovx-DS/obese) rats. Animals subjected to ovariectomy at 7 weeks of age were implanted subcutaneously with a 60-day release pellet containing 0.5 mg of 17β-estradiol (E(2)) or placebo at 8 weeks. Age-matched female homozygous lean littermates (DahlS.Z-Lepr(+)/Lepr(+) or DS/lean rats) of DS/obese rats served as controls. Animals were maintained on a normal diet and were subjected to echocardiography followed by various pathological analyses at 13 weeks of age. Ovx-DS/obese rats manifested hypertension at 7 weeks of age and thereafter and showed left ventricular (LV) fibrosis and diastolic dysfunction at 13 weeks. Treatment with E(2) attenuated hypertension in Ovx-DS/obese rats but had no effect on blood pressure in ovariectomized female DS/lean (Ovx-DS/lean) rats. E(2) treatment exacerbated LV fibrosis and diastolic dysfunction, as well as further increased cardiac oxidative stress and inflammation in Ovx-DS/obese rats, and it elicited similar effects in Ovx-DS/lean rats. E(2) reduced food intake, body weight, and visceral fat content in both Ovx-DS/obese and Ovx-DS/lean rats. E(2) treatment attenuated hypertension and obesity but exacerbated LV fibrosis and diastolic dysfunction in Ovx-DS/obese rats, with these latter effects being associated with increased cardiac oxidative stress and inflammation.

Relaxin and castration in male mice protect from, but testosterone exacerbates, age-related cardiac and renal fibrosis, whereas estrogens are an independent determinant of organ size

This study determined the effects of castration and hormone replacement therapy on the age-related cardiac and renal pathology of male relaxin gene-knockout (RlnKO) and age-matched wild-type (RlnWT) mice and that of aged male aromatase knockout (ArKO) mice, which lack estrogens and have 5-10 times the androgen levels of male wild-type mice. One-month-old RlnWT and RlnKO mice were bilaterally gonadectomized or sham operated and maintained until 12 months. Subgroups of castrated animals received testosterone or 17β-estradiol treatment from 9 to 12 months. Male ArKO mice and aromatase wild-type mice were aged to 12 months. Collected heart and kidney tissues were assessed for changes in organ size and fibrosis. Castration reduced body, heart, left ventricle, and kidney weights in both RlnKO and RlnWT mice, and the cardiac/renal fibrosis that was seen in sham RlnKO animals (all P < 0.05 vs. respective sham). Testosterone normalized organ weights and organ weight to body weight ratio of castrated animals and increased cardiac/renal collagen concentration to levels measured in or beyond that of sham RlnKO mice (all P < 0.05 vs. respective castrated mice). Furthermore, expression of TGF-β1, mothers against decapentaplegic homolog 2 (Smad2), and myofibroblast differentiation paralleled the above changes (all P < 0.05 vs. respective castrated mice), whereas matrix metalloproteinase-13 was decreased in testosterone-treated RlnKO mice. Conversely, 17β-estradiol only restored changes in organ size. Consistent with these findings, intact ArKO mice demonstrated increased cardiac/renal fibrosis in the absence of changes in organ size. These findings suggest that relaxin and castration protect, whereas androgens exacerbate, cardiac and renal fibrosis during ageing, whereas estrogens, in synergy with relaxin, regulates age-related changes in organ size.

Estrogen, hormonal replacement therapy and cardiovascular disease

PURPOSE OF REVIEW

Premenopausal women have a lower risk and incidence of hypertension and cardiovascular disease (CVD) compared to age-matched men and this sex advantage for women gradually disappears after menopause, suggesting that sexual hormones play a cardioprotective role in women. However, randomized prospective primary or secondary prevention trials failed to confirm that hormone replacement therapy (HRT) affords cardioprotection. This review highlights the factors that may contribute to this divergent outcome and could reveal why young or premenopausal women are protected from CVD and yet postmenopausal women do not benefit from HRT.

RECENT FINDINGS

In addition to the two classical estrogen receptors, ERα and ERβ, a third, G-protein-coupled estrogen receptor GPR30, has been identified. New intracellular signaling pathways and actions for the cardiovascular protective properties of estrogen have been proposed. In addition, recent Women's Health Initiative (WHI) studies restricted to younger postmenopausal women showed that initiation of HRT closer to menopause reduced the risk of CVD. Moreover, dosage, duration, the type of estrogen and route of administration all merit consideration when determining the outcome of HRT.

SUMMARY

HRT has become one of the most controversial topics related to women's health. Future studies are necessary if we are to understand the divergent published findings regarding HRT and develop new therapeutic strategies to improve the quality of life for women.

Suppression of endothelial P-selectin expression contributes to reduced cell trafficking in females: an effect independent of NO and prostacyclin

OBJECTIVE

Sex hormones underlie the lower incidence of cardiovascular disease in premenopausal women. Vascular inflammation is involved in the pathogenesis of several cardiovascular diseases and it has been reported that sex hormones modulate inflammatory responses but mechanisms responsible for these effects are not yet fully established. Herein, we assessed whether sex differences in leukocyte recruitment might exist and investigated the underlying mechanisms involved in this response.

METHODS AND RESULTS

Treatment with interleukin-1β (IL-1β) or tumor necrosis factor-α caused leukocyte rolling, adhesion, and emigration in mesenteric postcapillary venules in vivo that was substantially reduced in female mice compared with male mice; this difference was abolished by ovariectomy and partially restored by estrogen replacement. Deletion of endothelial nitric oxide (NO) synthase or cyclooxygenase-1 alone or in combination did not alter the leukocyte recruitment in IL-1β-treated females but significantly enhanced this response in male mice. Treatment of murine pulmonary endothelial cells with IL-1β increased expression of P-selectin in male but not female cells.

CONCLUSIONS

We have demonstrated a profound estrogen-dependent and NO and prostacyclin-independent suppression of leukocyte recruitment in females.

Dose-dependent toxic effects of high-dose estrogen on renal and cardiac injury in surgically postmenopausal mice

AIMS

We previously found that in mice with experimental myocardial infarction (MI), 17β-estradiol (E2) increased mortality and worsened cardiac remodeling and these deleterious effects were associated with renal enlargement and hydronephrosis in a dose-dependent manner. In the present study we questioned whether E2-induced renal damage predisposes to rather than results from its adverse effects on the heart.

MAIN METHODS

Ovariectomized (ovx) mice received either placebo (P) or E2 at 0.02 (E2-L, low dose), 0.42 (E2-M, moderate dose) or 4.2 μg/d (E2-H, high dose) for 8 weeks.

KEY FINDINGS

E2-L partially restored uterine weight and plasma estrogen levels without affecting heart, lung and liver weight, hemodynamic parameters, or heart and kidney morphology and function. E2-M restored normal uterine weight, but this was accompanied by a significant increase in kidney weight, albuminuria, glomerular matrix formation and markers for oxidative stress. E2-H increased uterine weight 4.5-fold and resulted in higher plasma creatinine levels, severe albuminuria, renal tubular dilatation, tubulointerstitial injury, hydronephrosis, glomerulosclerosis and oxidative stress. E2-H also caused ascites, hepatomegaly and fluid retention in the uterine horns but had no significant effect on blood pressure or heart function.

SIGNIFICANCE

Our data demonstrated that an excessive dose of E2 that raises uterine weight beyond physiological levels adversely affects the kidney even before it damages the heart. We believe estrogen dosage should be taken into account when considering hormonal replacement therapy, since inappropriate doses of E2 may damage not only the heart but also the kidney.

Signaling responses after exposure to 5 alpha-dihydrotestosterone or 17 beta-estradiol in norepinephrine-induced hypertrophy of neonatal rat ventricular myocytes

Androgens appear to enhance, whereas estrogens mitigate, cardiac hypertrophy. However, signaling pathways in cells for short (3 min) and longer term (48 h) treatment with 17beta-estradiol (E2) or 5 alpha-dihydrotestosterone (DHT) are understudied. We compared the effect of adrenergic stimulation by norepinephrine (NE; 1 microM) alone or in combination with DHT (10 nM) or E2 (10 nM) treatment in neonatal rat ventricular myocytes (NRVMs) by cell area, protein synthesis, sarcomeric structure, gene expression, phosphorylation of extracellular signal-regulated (ERK), and focal adhesion kinases (FAK), and phospho-FAK nuclear localization. NE alone elicited the expected hypertrophy and strong sarcomeric organization, and DHT alone gave a similar but more modest response, whereas E2 did not alter cell size. Effects of NE dominated when used with either E2 or DHT with all combinations. Both sex hormones alone rapidly activated FAK but not ERK. Long-term or brief exposure to E2 attenuated NE-induced FAK phosphorylation, whereas DHT had no effect. Neither hormone altered NE-elicited ERK activation. Longer term exposure to E2 alone reduced FAK phosphorylation and reduced nuclear phospho-FAK, whereas its elevation was seen in the presence of NE with both sex hormones. The mitigating effects of E2 on the NE-elicited increase in cell size and the hypertrophic effect of DHT in NRVMs are in accordance with results observed in whole animal models. This is the first report of rapid, nongenomic sex hormone signaling via FAK activation and altered FAK trafficking to the nucleus in heart cells.

17beta-Estradiol modulates local cardiac renin-angiotensin system to prevent cardiac remodeling in the DOCA-salt model of hypertension in rats

Ventricular remodeling can play a detrimental role in the progression of cardiovascular diseases, leading to heart failure. The current study was designed to investigate the effects of 17beta-estradiol (E2) on cardiac remodeling. Cardiac fibrosis and hypertrophy were examined in deoxycorticosterone acetate (DOCA)-salt treated rats with chronic, six-week administration of two different doses of E2. Bilaterally ovariectomized (Ovex) female Sprague-Dawley rats were randomly assigned to one of the following groups: Ovex-control; Ovex-DOCA; Ovex-DOCA+low-dose E2 (1.66 microg/day); or Ovex-DOCA+high-dose E2 (2.38 microg/day). All DOCA-treated rats were uninephrectomized and drinking water was replaced by 0.15M NaCl solution for the remainder of the study period. DOCA-salt treatment resulted in a significant increase in blood pressure, which was not altered by estrogen replacement. Histological examinations revealed marked cardiac remodeling (both ventricular hypertrophy and interstitial fibrosis) with DOCA treatment, which was attenuated in animals receiving estrogen therapy. Western blot analysis demonstrated increased cardiac levels of angiotensin converting enzyme (ACE) with DOCA treatment, which was attenuated by E2 replacement. Furthermore, increased levels of cardiac angiotensin converting enzyme 2 (ACE2) protein were observed in animals receiving high-dose E2 replacement. These findings suggest that physiologically relevant estrogen replacement therapy has blood pressure-independent cardioprotective effects, which are possibly mediated through modulation of the cardiac renin-angiotensin system.

Estrogen attenuates chronic volume overload induced structural and functional remodeling in male rat hearts

We have previously reported gender differences in ventricular remodeling and development of heart failure using the aortocaval fistula model of chronic volume overload in rats. In contrast to males, female rats exhibited no adverse ventricular remodeling and less mortality in response to volume overload. This gender-specific cardioprotection was lost following ovariectomy and was partially restored using estrogen replacement. However, it is not known if estrogen treatment would be as effective in males. The purpose of this study was to evaluate the structural and functional effects of estrogen in male rats subjected to chronic volume overload. Four groups of male rats were studied at 3 days and 8 wk postsurgery as follows: fistula and sham-operated controls, with and without estrogen treatment. Biochemical and histological studies were performed at 3 days postsurgery, with chronic structural and functional effects studied at 8 wk. Measurement of systolic and diastolic pressure-volume relationships was obtained using a blood-perfused isolated heart preparation. Both fistula groups developed significant ventricular hypertrophy after 8 wk of volume overload. Untreated rats with fistula exhibited extensive ventricular dilatation, which was coupled with a loss of systolic function. Estrogen attenuated left ventricular dilatation and maintained function in treated rats. Estrogen treatment was also associated with a reduction in oxidative stress and circulating endothelin-1 levels, as well as prevention of matrix metalloproteinase-2 and -9 activation and breakdown of ventricular collagen in the early stage of remodeling. These data demonstrate that estrogen attenuates ventricular remodeling and disease progression in male rats subjected to chronic volume overload.