Endogenous estrogen levels are associated with endothelial function in males independently of lipid levels

Estrogen and the Vascular Endothelium: The Unanswered Questions

Premenopausal women have a lower incidence of cardiovascular disease (CVD) compared with their age-matched male counterparts; however, this discrepancy is abolished following the transition to menopause or during low estrogen states. This, combined with a large amount of basic and preclinical data indicating that estrogen is vasculoprotective, supports the concept that hormone therapy could improve cardiovascular health. However, clinical outcomes in individuals undergoing estrogen treatment have been highly variable, challenging the current paradigm regarding the role of estrogen in the fight against heart disease. Increased risk for CVD correlates with long-term oral contraceptive use, hormone replacement therapy in older, postmenopausal cisgender females, and gender affirmation treatment for transgender females. Vascular endothelial dysfunction serves as a nidus for the development of many cardiovascular diseases and is highly predictive of future CVD risk. Despite preclinical studies indicating that estrogen promotes a quiescent, functional endothelium, it still remains unclear why these observations do not translate to improved CVD outcomes. The goal of this review is to explore our current understanding of the effect of estrogen on the vasculature, with a focus on endothelial health. Following a discussion regarding the influence of estrogen on large and small artery function, critical knowledge gaps are identified. Finally, novel mechanisms and hypotheses are presented that may explain the lack of cardiovascular benefit in unique patient populations.

Association of sex hormones with metabolic syndrome among Egyptian males

BACKGROUND

Studies have shown that testosterone and estradiol (E2) are associated with metabolic syndrome (MetS). To our knowledge, few studies, if any about the association of endogenous sex hormones with MetS have been done in Egypt.

AIM

To study the relation between endogenous sex hormones and MetS among Egyptian males.

SUBJECTS AND METHOD

For the study, 80 Egyptian males were enrolled: 40 males with MetS and 40 healthy age-matched males. Anthropometric measurements and blood pressure were taken for both groups. FBG, TC, HDL-C, TG, testosterone, and E2 levels were determined; LDL-C was calculated.

RESULTS

Males with MetS had significantly lower testosterone levels and significantly higher E2 levels compared to those without MetS (p value 0.0001). The lowest quartile of testosterone was most prevalent among males with MetS (19/40 males, 47.5%) compared to those without MetS (0/40 males, 0%, p value 0.011). Estradiol in the third quartile was most prevalent among males with MetS (19/40 males, 47.5%) compared to those without MetS (1/40 males, 2.5%, p value 0.0001). Serum testosterone and E2 levels were independent predictors of MetS with optimum cut off value (≤2.37ng/ml) for testosterone and (>16.78pg/ml) for E2.

CONCLUSION

Endogenous testosterone and estradiol are independently associated with MetS with potential utility as predictors of MetS.

Endothelial maintenance in health and disease: Importance of sex differences

The vascular endothelium has emerged as more than just an inert monolayer of cells lining the vascular bed. It represents the interface between the blood stream and vessel wall, and has a strategic role in regulating vascular homeostasis by the release of vasoactive substances. Endothelial dysfunction contributes to the development and progression of cardiovascular disease. Recognition of sex-specific factors implicated in endothelial cell biology is important for the identification of clinically relevant preventive and/or therapeutic strategies. This review aims to give an overview of the recent advances in understanding the importance of sex specific observations in endothelial maintenance, both in healthy and diseased conditions. The female endothelium is highlighted in the context of polycystic ovary syndrome and pre-eclampsia. Furthermore, sex differences are explored in chronic kidney disease, which is currently appreciated as one of public health priorities. Overall, this review endorses integration of sex analysis in experimental and patient-oriented research in the exciting field of vascular biology.

Synergistic Effect of a Physiological Ratio of Estradiol and Testosterone in the Treatment of Early-stage Atherosclerosis

BACKGROUND AND AIMS

Clinical trials and epidemiological data suggest that estrogen replacement therapy (ERT) fails to reduce cardiovascular events in postmenopausal women with coronary heart disease (CHD). The high concentration of estrogen supplementation may increase the risk of thrombosis and result in testosterone deficiency, which is considered the main reason for failure. Thus, we hypothesized that a physiologic dosage of estradiol combined with testosterone may become a new therapeutic strategy in postmenopausal women with CHD.

METHODS AND RESULTS

We used human umbilical vein endothelial cells (HUVECs) and female C57BL/6 mice as the experimental subjects. With the HUVECs, we found an appropriate E2/T ratio of 5:1 (5×10(-8) mol/L estradiol and 10(-8) mol/L testosterone), which has a significant anti-apoptotic effect on HUVECs by inducing a C-reactive protein. In the in vivo study, we verified the beneficial effects of the defined appropriate E2/T ratio in mice with early stage atherosclerosis. We found that replacement therapy with the defined appropriate E2/T ratio had beneficial effects of reducing the lipid lesions, reducing the formation of foam cells, reducing endothelial injury, modulating the coagulation system function and inhibiting inflammation and was significantly more effective than either estradiol or testosterone supplementation alone.

CONCLUSION

The present study demonstrated that estradiol and testosterone have a synergistic effect on early stage atherosclerosis, and replacement therapy with the defined appropriate E2/T ratio can significantly suppress the development of atherosclerosis through reducing the lipid lesions, reducing the formation of foam cells, reducing endothelial injury, modulating the coagulation system function and inhibiting inflammation.

Determinants of testosterone levels in human male obesity

Testosterone (T) levels are decreased in obese men, but the underlying causes are incompletely understood. Our objective was to explore the relation between low (free) T levels and male obesity, by evaluating metabolic parameters, subcutaneous adipose tissue (SAT) aromatase expression, and parameters of the hypothalamic-pituitary-gonadal axis. We recruited 57 morbidly obese men [33 had type 2 diabetes (DM2)] and 25 normal-weight men undergoing abdominal surgery. Fourteen obese men also attended a follow-up, 2 years after gastric bypass surgery (GBS). Circulating T levels were quantified by LC-MS/MS, whereas free T levels were measured using serum equilibrium dialysis and sex hormone-binding globulin, luteinizing hormone, and follicle-stimulating hormone by immunoassay. SAT biopsies were used to determine adipocyte cell size and aromatase expression by real-time PCR. Total and free T levels were decreased in obese males versus controls, with a further decrease in obese men with DM2 versus obese men without DM2. There were no differences in aromatase expression among the study groups, and sex steroids did not correlate with aromatase expression. Pearson analysis revealed an inverse association between (free) T and SAT cell size, triglycerides, and HOMA-IR. Multivariate analysis confirmed the inverse association between (free) T and SAT cell size (β = -0.321, P = 0.037 and β = -0.441, P = 0.011, respectively), independent of age, triglycerides, HOMA-IR, obesity, or diabetes. T levels were normalized 2 years after GBS. These data suggest that SAT cell size rather than SAT aromatase expression or parameters of the hypothalamic-pituitary-gonadal axis is related to low T in male obesity, which points to adipose cell size-related metabolic changes as a major trigger in decreased T levels.

Estrogen receptor inhibits mineralocorticoid receptor transcriptional regulatory function

The steroid hormone aldosterone (aldo) contributes to cardiovascular disease in animal models and in humans. Aldo activates the mineralocorticoid receptor (MR), a hormone-activated transcription factor, and indeed, pharmacological MR inhibition improves cardiovascular outcomes. Because the incidence of cardiovascular disease is lower in premenopausal women, we hypothesized that estrogen (E2) signaling through the estrogen receptor (ER) may protect the vasculature by inhibiting the detrimental effects of aldo signaling through the MR. We demonstrate that E2-activated ER inhibits MR-mediated gene transcription from the mouse mammary tumor virus reporter in human embryonic kidney-293 cells. In contrast, aldo-activated MR does not affect ER-mediated gene transcription. The ERα N terminus (amino acids 1-253) containing part of the DNA-binding domain is sufficient to inhibit MR genomic function, although point mutations reveal that DNA binding, ligand-independent activation, and rapid nongenomic ERα signaling are not required for this effect. Furthermore, ERα and MR are part of a complex in cell lysates, with amino acids 1-233 of the ERα N terminus being sufficient to complex with the MR. Overall, the ability of ERα to inhibit MR-mediated gene transcription correlates with the ability of ERα segments to both localize to the nucleus and complex with the MR. In cultured vascular endothelial cells expressing ERα, E2 inhibits aldo induction of the vascular MR target gene intercellular adhesion molecule-1 (ICAM-1). ICAM-1 induction by endothelial MR is known to promote vascular inflammation that could contribute to the mechanism of aldo-induced atherosclerosis. E2 also inhibits aldo induction of ICAM-1 protein and prevents aldo-enhanced leukocyte adhesion to endothelial cells. These studies support a new model in which E2-activated ER in endothelial cells forms a complex with MR in the nucleus to modulate MR regulation of the proinflammatory gene ICAM-1. Estrogen inhibition of MR regulation of genes that contribute to cardiovascular disease may be a new mechanism by which premenopausal women are protected from cardiovascular disease.

Gender disparity in LDL-induced cardiovascular damage and the protective role of estrogens against electronegative LDL

Background

Increased levels of the most electronegative type of LDL, L5, have been observed in the plasma of patients with metabolic syndrome (MetS) and ST-segment elevation myocardial infarction and can induce endothelial dysfunction. Because men have a higher predisposition to developing coronary artery disease than do premenopausal women, we hypothesized that LDL electronegativity is increased in men and promotes endothelial damage.

Methods

L5 levels were compared between middle-aged men and age-matched, premenopausal women with or without MetS. We further studied the effects of gender-influenced LDL electronegativity on aortic cellular senescence and DNA damage in leptin receptor–deficient (db/db) mice by using senescence-associated–β-galactosidase and γH2AX staining, respectively. We also studied the protective effects of 17β-estradiol and genistein against electronegative LDL–induced senescence in cultured bovine aortic endothelial cells (BAECs).

Results

L5 levels were higher in MetS patients than in healthy subjects (P < 0.001), particularly in men (P = 0.001). LDL isolated from male db/db mice was more electronegative than that from male or female wild-type mice. In addition, LDL from male db/db mice contained abundantly more apolipoprotein CIII and induced more BAEC senescence than did female db/db or wild-type LDL. In the aortas of db/db mice but not wild-type mice, we observed cellular senescence and DNA damage, and the effect was more significant in male than in female db/db mice. Pretreatment with 17β-estradiol or genistein inhibited BAEC senescence induced by male or female db/db LDL and downregulated the expression of lectin-like oxidized LDL receptor-1 and tumor necrosis factor-alpha protein.

Conclusion

The gender dichotomy of LDL-induced cardiovascular damage may underlie the increased propensity to coronary artery disease in men.

The Effect of Testosterone on Cardiovascular Disease

Cardiovascular disease is the leading cause of death in the United States. Testosterone is the principal male sex hormone and plays an important role in men’s health and well-being. Historically, testosterone was believed to adversely affect cardiovascular function. However, contemporary literature has refuted this traditional thinking; testosterone has been suggested to have a protective effect on cardiovascular function through its effects on the vascular system. Data from modern research indicate that hypogonadism is closely related to the development of various cardiovascular risk factors, including hyperlipidemia and insulin resistance. Several studies have demonstrated beneficial effects of testosterone supplementation therapy on reversing symptoms of hypogonadism and improving cardiovascular disease risk profiles. In this review, we perform a critical analysis on the association between testosterone and cardiovascular disease.

Impact of the association between elevated oestradiol and low testosterone levels on erectile dysfunction severity

Our aim was to assess the impact of the association between elevated oestradiol (E2) and low testosterone (T) levels on erectile dysfunction (ED) severity. A total of 614 male patients with ED and a normal or low T level in association with normal or elevated E2 levels were enrolled. Patients underwent routine laboratory investigations in addition to measurements of total T, total E2, follicle-stimulating hormone (FSH), luteinizing hormone (LH) and prolactin. We compared the responses to the erectile function domain, Q3 (achieving erection) and Q4 (maintaining erection) of the International Index for Erectile Function (IIEF) score in patients with the following: normal T and E2 levels; low T level; low T level and elevated E2 level; and elevated E2 level. Of the patients included, 449 (73.1%) had normal T and E2 levels, 110 (17.9%) had a low T level, 36 (5.9%) had a low T level and an elevated E2 level, and 19 (3.1%) had an elevated E2 level. Increased ED severity was significantly associated with low T levels, elevated E2 levels, and both a low T level and an elevated E2 level. Additionally, the mean values of the EF-domain, Q3 and Q4 were significantly lower in patients with both a low T level and an elevated E2 level compared to patients with any condition alone. In conclusion, a low T level had the primary effect on erectile function; however, a concomitantly elevated E2 level had an additive impairment effect.

SHBG and endothelial function in older subjects

BACKGROUND

Endothelial dysfunction is predictor of cardiovascular diseases that have different prevalence in men and women before menopause. Sex hormones and sex hormone binding globulin (SHBG), novel risk factors for diabetes and cardiovascular diseases even in older individuals, might explain this difference. However, the relationship between these hormones and endothelial function has never been addressed in the elderly.

METHODS AND RESULTS

430 men and,424 women 70 years older of Prospective Study of the Vasculature in Uppsala Seniors study, with complete data on SHBG, testosterone(T), estradiol(E2), endothelium-independent vasodilation (EIDV), endothelium-dependent vasodilation(EDV), flow-mediated vasodilation (FMD) and the pulse wave analysis (reflection index, RI) were evaluated. Multivariate regression analysis adjusted for confounders was used to assess the relationship between T, E2, SHBG and endothelial function. In men we found a positive relationship between SHBG and EDV (β ± SE 3.60 ± 0.83, p<0.0001), EIDV (2.42 ± 0.58, p<0.0001) but not with FMD. The relationship between SHBG and EDV and EIDV was maintained after adjustment for sex (1.64 ± 0.47, p<0.001 and 1.79 ± 0.35, p<0.0006, respectively). After adjustment for confounders, the relationship between SHBG and EDV and EIDV was still statistically significant (2.63 ± 0.90 and 1.86 ± 0.63, p = 0.004 for both). In women SHBG and EIDV were positively associated (1.58 ± 0.46; p = 0.0007), and this relationship was independent of sex (1.79 ± 0.35; p<0.001). No significant interaction SHBG * SEX was found for EIDV (p = 0.72). In a combined analysis in two sexes, SHBG and EIDV were positively associated (1.13 ± 0.45; p = 0.01). SHBG was not associated with EDV, FMD and RI. No significant relationship was found between T or E2 and EDV, EIDV, FMD or RI in both sexes.

CONCLUSIONS

In older men SHBG, but not T and E2, is positively and independently associated with EDV in resistance arteries. In both sexes, SHBG was positively and independently associated with EIDV.

The impact of estradiol and 1,25(OH)2D3 on metabolic syndrome in middle-aged Taiwanese males

In addition to adipocytokines, estradiol (E2) and vitamin D have been reported to affect insulin sensitivity, glucose homeostasis and body weight. However, studies about the impact of E2 and vitamin D on metabolic syndrome (MetS) are still limited. The aim of this study is to clarify the roles of circulating E2 and vitamin D on the risk of MetS in middle-aged Taiwanese males. A total of 655 male volunteers, including 243 subjects with MetS (mean age: 56.7±5.8 years) and 412 normal controls (mean age: 55.1±3.6 years), were evaluated. Subjects with MetS had significantly lower circulating E2, 1,25(OH)₂D₃, and adiponectin, and higher leptin than those without MetS (P<0.001 for all comparisons). E2 and 1,25(OH)₂D₃ were significantly associated with 4 individual components of MetS; more than adiponectin and leptin that were only associated with 3 individual components. In multivariate regression analysis, E2 (beta = −0.216, P<0.001) and 1,25(OH)₂D₃ (beta = 0.067, P = 0.045) were still significant predictors of MetS independent of adiponectin and leptin. Further large studies are needed to confirm our preliminary results and elucidate the possible mechanism.

Testosterone and heart failure

Testosterone deficiency is a generalized phenomenon seen in the course of chronic heart failure (CHF). Reduction in circulating testosterone level is a predictor of deterioration of functional capacity over time, underscoring the role of testosterone deficiency in CHF. Anabolic hormones are determinants of exercise capacity and circulating levels of anabolic hormones strongly determine muscle mass and strength. Testosterone deficiency is involved in the pathophysiology of CHF, contributing to some features of this syndrome, such as the reduced muscle mass, abnormal energy handling, fatigue, dyspnea and, finally, cachexia. This review summarizes current knowledge on the role of testosterone deficiency in the pathophysiology of CHF, gaining insights from the potential implications of testosterone as supplementation therapy.

Role of Endogenous Estrogen on the Incidence of Coronary Heart Disease in Men

Estrogens protect the vascular system in women, but its effect in men is unclear. We evaluated the impact of estrogen on the male cardiovascular system. Of 140 Chinese males, 55 (aged 61.2 ± 3.5) were cases and 60 (aged 59.5 ± 4.6) were controls. Compared with the control group, only serum estradiol ([E2]; P < .01) levels but not testosterone ([T]; P = .21) were significantly lower in the cases. Linear and multiple regression analysis showed that serum T was positively associated with triglycerides ([TG]; r = .439, P < .01) and d-dimer ( r = .258, P < .05) but negatively associated with high-density lipoprotein cholesterol (HDL-C) levels ( r = −.267, P < .05) and C-reactive protein (CRP; r = −.214, P < .05). Estradiol was highly associated with TG ( r = .783, P < .01) and HDL-C ( r = .515, P < .01) but was negatively related with low-density lipoprotein cholesterol (LDL-C; P < .05), total cholesterol/HDL-C ( P < .05), CRP ( P < .01), and d-dimer ( P < .01). In conclusion, serum E2 and T levels affect coronary heart disease risk factors in males.

Erectile dysfunction can improve the effectiveness of the current guidelines for the screening for asymptomatic coronary artery disease in diabetes

About 40% of diabetic patients with asymptomatic coronary artery disease (CAD) are missed on the basis of the current screening guidelines. Erectile Dysfunction (ED) is a powerful marker of asymptomatic CAD. Aim of the study is to evaluate whether ED can improve the effectiveness of the current guidelines for the screening of CAD in diabetes. From among 299 consecutive men with newly diagnosed type 2 diabetes without any apparent vascular complication, 293 (mean age 56.6±5.9 years) were enrolled. Among them, 219 did not have myocardial ischemia (NO CAD group) and 74 men had a coronary stenosis angiographically proven (CAD group). Five risk factors (RFs) of the current screening guidelines (hypertension, dyslipidemia, family history for CAD, smoking e micro/macroalbuminuria) and ED were assessed. ED was significantly more prevalent in the CAD than in the NO CAD group (37.8 versus 15.1%; P<0.001) and was a predictor of asymptomatic CAD (OR: 4.4; 95%CI: 2.1-9.0; P<0.001). If ED is added to the list of RFs, it can increase the sensitivity of the current guidelines from 62 to 89%, without a significant variation in specificity (from 60 to 57%). The negative predictive value can increase from 82 to 94%. ED can reduce from 37.84 to 10.81% the percentage of patients with silent CAD missed at the screening. This study first shows that ED can improve the effectiveness in discriminating diabetic men to screen for asymptomatic CAD, when it is added to the list of RFs of the current screening guidelines.