Inhibition of postmenopausal atherosclerosis progression: a comparison of the effects of conjugated equine estrogens and soy phytoestrogens

A Comprehensive Review on the Effects of Vegetarian Diets on Coronary Heart Disease

Coronary heart disease (CHD) is one of the leading causes of morbidity and mortality worldwide. Dietary modifications in the form of a vegetarian diet can perhaps be the key to the prevention and management of cardiovascular diseases. The aims of this review are to determine the association between a vegetarian diet and CHD, to compare the risk of CHD in different types of vegetarian diets, and to assess variability in the biochemical predictors of CHD in the various vegetarian diets. Our study inferred that adherence to a plant-based diet was inversely related to the incidence of heart failure risk. Our research further supports the idea that a vegetarian diet is advantageous for the secondary prevention of CHD since it alters lipid profiles, lowers body mass index (BMI), and increases plasma antioxidant micronutrient concentrations. Additionally, eating a plant-based diet starting in adolescence is linked to a decreased risk of cerebrovascular disease (CVD) by middle age. An increase in sensitization and education efforts is imperative to ensure that people are appropriately informed about this option to significantly improve their quality of life.

Maximizing the Estrogenic Potential of Soy Isoflavones through the Gut Microbiome: Implication for Cardiometabolic Health in Postmenopausal Women

Soy isoflavones have been suggested as an alternative treatment for managing postmenopausal symptoms and promoting long-term health due to their structural similarity to mammalian estrogen and ability to bind to estrogen receptors. Among all soy isoflavones and their metabolites, (S)-equol is known for having the strongest estrogenic activity. Equol is a metabolite of the soy isoflavone daidzein produced through intestinal bacterial metabolism. However, more than half of the human population is not able to produce equol due to the lack of equol-producing bacteria in their gastrointestinal tract. The interpersonal variations in the gut microbiome complicate the interpretation of data collected from humans. Furthermore, because rodents are efficient equol-producers, translatability between rodent models and humans is challenging. Herein, we first summarized the current knowledge of the microbial conversion of daidzein to equol, its relation to health, and proposed the need for developing model systems by which equol production can be manipulated while controlling other known confounding factors. Determining the necessity of equol-producing capacity within a gut microbial community when consuming soy as a functional ingredient, and identifying strategies to maximize equol production by modulating the gut microbiome, may provide future therapeutic approaches to improve the health of postmenopausal women.

Potential Protective Effects of Equol (Soy Isoflavone Metabolite) on Coronary Heart Diseases-From Molecular Mechanisms to Studies in Humans

Equol, a soy isoflavone-derived metabolite of the gut microbiome, may be the key cardioprotective component of soy isoflavones. Systematic reviews have reported that soy isoflavones have no to very small effects on traditional cardiovascular disease risk factors. However, the potential mechanistic mode of action of equol on non-traditional cardiovascular risk factors has not been systematically reviewed. We searched the PubMed through to July 2021 by using terms for equol and each of the following markers: inflammation, oxidation, endothelial function, vasodilation, atherosclerosis, arterial stiffness, and coronary heart disease. Of the 231 records identified, 69 articles met the inclusion criteria and were summarized. Our review suggests that equol is more lipophilic, bioavailable, and generally more potent compared to soy isoflavones. Cell culture, animal, and human studies show that equol possesses antioxidative, anti-inflammatory, and vasodilatory properties and improves arterial stiffness and atherosclerosis. Many of these actions are mediated through the estrogen receptor β. Overall, equol may have a greater cardioprotective benefit than soy isoflavones. Clinical studies of equol are warranted because equol is available as a dietary supplement.

Soy intake and chronic disease risk: findings from prospective cohort studies in Japan

There has been much interest in the potential role of soy in reducing the risk of chronic diseases. Soy foods are uniquely rich in isoflavones, a fact that has triggered much research including intervention studies. However, there have been few long-term prospective observational studies that include disease itself as an outcome. High intake of soy foods is intrinsic to the Japanese diet, which can be advantageous for conducting such studies in Japan. The present report reviews the findings from Japanese prospective cohort studies on soy intake and the risk of cardiovascular diseases, cancer, type 2 diabetes, osteoporosis, menopausal symptoms, and dementia. The results suggest a beneficial role of soy in several chronic diseases, but they are not without controversy. Discrepancies have been observed in the findings of studies of Japanese or other Asians as compared to those of non Asians. This review discusses the issues to be explored in future studies.

Female Mice Exhibit Abdominal Aortic Aneurysm Protection in an Established Rupture Model

BACKGROUND

Male gender is a well-established risk factor for abdominal aortic aneurysm (AAA), whereas estrogen is hypothesized to play a protective role. Although rupture rates are higher in women, these reasons remain unknown. In the present study, we sought to determine if female mice are protected from AAA rupture.

MATERIALS AND METHODS

Apolipoprotein E-deficient male and female mice (aged 7 wk; n = 25 per group) were infused with angiotensin II (AngII; 2000 ng/kg/min) plus β-aminopropionitrile (BAPN) in the drinking water for 28 d to test the effects of gender on AAA rupture. Separately, a second group of male apolipoprotein E-deficient mice underwent AngII infusion + BAPN while being fed high-fat phytoestrogen free or a high-fat phytoestrogen diet to assess effects of phytoestrogens on rupture. In a third group, female mice either underwent oophorectomy or sham operation 4 wk before infusion of AngII and BAPN to further test the effects of female hormones on AA rupture. Surviving mice abdominal aorta were collected for histology, cytokine array, and gelatin zymography on postoperative day 28.

RESULTS

Female mice had decreased AAA rupture rates (16% versus 46%; P = 0.029). Female mice expressed fewer elastin breaks (P = 0.0079) and decreased smooth muscle cell degradation (P = 0.0057). Multiple cytokines were also decreased in the female group. Gelatin zymography demonstrated significantly decreased pro-matrix metalloproteinase 2 in female mice (P = 0.001). Male mice fed a high dose phytoestrogen diet failed to decrease AAA rupture. Female mice undergoing oophorectomy did not have accelerated aortic rupture.

CONCLUSIONS

These data are the first to attempt to tease out hormonal effects on AAA rupture and the possible role of gender in rupture.

Effect of S-equol and Soy Isoflavones on Heart and Brain

BACKGROUND

Observational studies in Asia show that dietary intake of soy isoflavones had a significant inverse association with coronary heart disease (CHD). A recent randomized controlled trial (RCT) of soy isoflavones on atherosclerosis in the US, however, failed to show their benefit. The discrepancy may be due to the much lower prevalence of S-equol producers in Westerners: Only 20-30% of Westerners produce S-equol in contrast to 50-70% in Asians. S-equol is a metabolite of dietary soy isoflavone daidzein by gut microbiome and possesses the most antiatherogenic properties among all isoflavones. Several short-duration RCTs documented that soy isoflavones improves arterial stiffness. Accumulating evidence shows that both atherosclerosis and arterial stiffness are positively associated with cognitive decline/dementia. Therefore, potentially, soy isoflavones, especially S-equol, are protective against cognitive decline/dementia.

METHODS/RESULTS

This narrative review of clinical and epidemiological studies provides an overview of the health benefits of soy isoflavones and introduces S-equol. Second, we review recent evidence on the association of soy isoflavones and S-equol with CHD, atherosclerosis, and arterial stiffness as well as the association of atherosclerosis and arterial stiffness with cognitive decline/ dementia. Third, we highlight recent studies that report the association of soy isoflavones and S-equol with cognitive decline/dementia. Lastly, we discuss the future directions of clinical and epidemiological research on the relationship of S-equol and CHD and dementia.

CONCLUSIONS

Evidence from observational studies and short-term RCTs suggests that S-equol is anti-atherogenic and improves arterial stiffness and may prevent CHD and cognitive impairment/ dementia. Well-designed long-term (≥ 2years) RCTs should be pursued.

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.

Oxidative Stress: Harms and Benefits for Human Health

Oxidative stress is a phenomenon caused by an imbalance between production and accumulation of oxygen reactive species (ROS) in cells and tissues and the ability of a biological system to detoxify these reactive products. ROS can play, and in fact they do it, several physiological roles (i.e., cell signaling), and they are normally generated as by-products of oxygen metabolism; despite this, environmental stressors (i.e., UV, ionizing radiations, pollutants, and heavy metals) and xenobiotics (i.e., antiblastic drugs) contribute to greatly increase ROS production, therefore causing the imbalance that leads to cell and tissue damage (oxidative stress). Several antioxidants have been exploited in recent years for their actual or supposed beneficial effect against oxidative stress, such as vitamin E, flavonoids, and polyphenols. While we tend to describe oxidative stress just as harmful for human body, it is true as well that it is exploited as a therapeutic approach to treat clinical conditions such as cancer, with a certain degree of clinical success. In this review, we will describe the most recent findings in the oxidative stress field, highlighting both its bad and good sides for human health.

Beneficial effects of soy supplementation on postmenopausal atherosclerosis are dependent on pretreatment stage of plaque progression

OBJECTIVE

The objective of this study was to use a well-established monkey model of atherosclerosis to determine how life stage and preexisting atherosclerosis influence the effectiveness of high-isoflavone soy diet in inhibiting progression of atherosclerosis.

METHODS

For 34 months, premenopausal monkeys were fed an atherogenic diet, with protein derived primarily from either animal sources (casein-lactalbumin [CL], n = 37) or high-isoflavone soy beans (Soy, n = 34). Animals were ovariectomized and randomized to groups fed the same diet (CL-CL, n = 20; Soy-Soy, n = 17) or an alternate diet (CL-Soy, n = 17; Soy-CL, n = 17) for an additional 34 months. At ovariectomy, the left common iliac artery was removed to determine the amount of premenopausal atherosclerosis. At necropsy, the right common iliac artery and coronary arteries were collected, and atherosclerosis extent was quantified. CL-CL condition was considered "control."

RESULTS

Modeling Asian women who remain in Asia, monkeys fed soy protein both premenopausally and postmenopausally had a markedly reduced extent of coronary artery atherosclerosis relative to CL controls (P = 0.008). The subset of animals that modeled Asian women who migrate to a Western country (consuming soy premenopausally and CL postmenopausally) had increased progression of postmenopausal iliac artery atherosclerosis (P = 0.003) and was not protected against the development of coronary artery atherosclerosis relative to controls. Relevant to the administration of soy diets to postmenopausal Western women, monkeys fed CL premenopausally and switched to soy postmenopausally derived atheroprotective benefits only if they began the postmenopausal treatment period with relatively small (below the median) plaques. Relative to controls, this group (with small plaques at ovariectomy) had reduced progression of iliac atherosclerosis (P = 0.038) and smaller coronary artery plaques (P = 0.0001) that were less complicated (P = 0.05) relative to controls.

CONCLUSIONS

The results suggest that significant atheroprotective benefits of dietary soy are derived from treatment that begins premenopausally and continues postmenopausally or from treatment that is started during early postmenopause (when plaques are still small).

Effects of long-term sertraline treatment and depression on coronary artery atherosclerosis in premenopausal female primates

OBJECTIVES

Major depressive disorder and coronary heart disease often co-occur in the same individuals. Selective serotonin reuptake inhibitors (SSRIs) are widely prescribed for depression and other disorders, but their effects on coronary heart disease risk remain unclear. We determined the effects of an SSRI on coronary artery atherosclerosis (CAA) in an established nonhuman primate model used to clarify the association between depression and CAA.

METHODS

Forty-two adult female cynomolgus macaques consuming a Western diet were characterized during an 18-month pretreatment phase and assigned to SSRI (sertraline hydrochloride 20 mg/kg, per os, once a day) or placebo balanced on pretreatment depression, body weight (BW), and iliac artery atherosclerosis extent measured via biopsy. After 18 months, CAA extent was measured using histomorphometry.

RESULTS

Before and during treatment, depressed monkeys had lower BW, body mass index, and plasma high-density lipoprotein cholesterol, and higher heart rates during the pretreatment (p < .01) but not the treatment phase (p = .17). There were no pretreatment differences between the sertraline and placebo groups. Sertraline reduced anxious behavior but had no effect on BW, body mass index, heart rate, plasma lipids, or depression. CAA, analyzed by a 2 (depressed, nondepressed) × 2 (placebo, sertraline) × 3 (coronary arteries) analysis of covariance adjusted for pretreatment iliac atherosclerosis, was greater in depressed than in nondepressed monkeys (p < .036), and in sertraline than in placebo-treated monkeys (p = .040). The observed CAA extent in depressed monkeys treated with sertraline was 4.9 times higher than that in untreated depressed monkeys, and 6.5 times higher than that in nondepressed monkeys, on average.

CONCLUSIONS

Depressed animals developed more CAA, and long-term treatment with sertraline resulted in more extensive CAA.

Effects of estradiol on transcriptional profiles in atherosclerotic iliac arteries in ovariectomized cynomolgus macaques

OBJECTIVE

This study aimed to assess the in vivo effects of estradiol treatment on arterial gene expression in atherosclerotic postmenopausal female monkeys.

METHODS

Eight ovariectomized cynomolgus monkeys were fed atherogenic diets for 6.5 years. The left iliac artery was biopsied before randomization to the estradiol group (human equivalent dose of 1 mg/d, n = 4) or the vehicle group (n = 4) for 8 months. The right iliac artery was obtained at necropsy. Transcriptional profiles in pretreatment versus posttreatment iliac arteries were compared to assess the responses of atherosclerotic arteries to estradiol.

RESULTS

Iliac artery plaque size did not differ between the estradiol group and the placebo group at baseline or during the treatment period. Nevertheless, estradiol treatment was associated with increased expression of 106 genes and decreased expression of 26 genes in the iliac arteries. Estradiol treatment increased the expression of extracellular matrix genes, including the α1 chain of type I collagen, the α2 chain of type VI collagen, and fibulin 2, suggestive of an increase in the proportion or phenotype of smooth muscles or fibroblasts in lesions. Also increased were components of the insulin-like growth factor pathway (insulin-like growth factor 1, insulin-like growth factor binding protein 4, and insulin-like growth factor binding protein 5) and the Wnt signaling pathway (secreted frizzled-related protein 2, secreted frizzled-related protein 4, low-density lipoprotein receptor-related protein 6, and Wnt1-inducible signaling pathway protein 2).

CONCLUSIONS

Estradiol treatment of monkeys with established atherosclerosis affected iliac artery gene expression, suggesting changes in the cellular composition of lesions. Moreover, it is probable that the presence of atherosclerotic plaque affected the gene expression responses of arteries to estrogen.

Effects of bazedoxifene, conjugated equine estrogens, and a tissue-selective estrogen complex containing both bazedoxifene and conjugated equine estrogens on cerebral artery atherosclerosis in postmenopausal monkeys

OBJECTIVE

This study aims to evaluate the effects of a new selective estrogen receptor modulator (bazedoxifene acetate [BZA]) and a tissue-specific estrogen complex (BZA combined with conjugated equine estrogens [CEE]) on the extent and severity of cerebral artery atherosclerosis.

METHODS

Ninety-eight surgically postmenopausal monkeys (Macaca fascicularis) were fed a moderately atherogenic diet and randomized to receive no treatment or women's equivalent doses of BZA (20 mg/d), CEE (0.45 mg/d), or BZA + CEE. After an experimental period of 20 months (approximately equivalent to 5 years of participant experience), the extent and severity of atherosclerosis in the common carotid artery, carotid bifurcation, internal carotid artery, and basilar artery were determined. Lesion severity was determined using the American Heart Association grading system (grades 0-V).

RESULTS

BZA had no consistent adverse effects on the extent and severity of atherosclerosis in the cerebral arteries and did not attenuate the beneficial effects of CEE on the severity of common carotid artery atherosclerosis. Although CEE had only modest beneficial effects on the extent of carotid bifurcation atherosclerosis, the severity of lesions and the number of affected cases in the common carotid artery were reduced with CEE treatment. As reported previously, plasma lipid profiles did not differ among the treatment groups.

CONCLUSIONS

In this long-term (equivalent to 5 human patient-years) nonhuman primate trial, BZA shows no consistent adverse effect on cerebral artery atherosclerosis and does not attenuate the modest beneficial effect of CEE on the common carotid artery. Furthermore, CEE inhibits the development of complicated plaques in the common carotid artery.

Effects of equol on gene expression in female cynomolgus monkey iliac arteries

BACKGROUND AND AIMS

To examine effects of equol, the soy phytoestrogen metabolite, on gene expression in the monkey iliac artery.

METHODS AND RESULTS

A high fat/high cholesterol diet was fed to eight ovariectomized cynomolgus monkeys for 6.5 years. After biopsy of the left iliac artery, the animals were randomized to two treatment groups for 8 months; the treatment groups were equol (23.7 mg/100 g diet, n = 4) and vehicle (n = 4). The right iliac artery was removed at necropsy. Gene expression in the iliac arteries in response to equol was determined by DNA microarray. Comparison of atherosclerotic lesions and plasma lipids at pre-versus post-equol treatment time points and in vehicle versus equol treatment groups did not identify any significant differences. Despite the lack of effect of equol on these parameters, 59 genes were down-regulated and 279 were up-regulated in response to equol. Comparison of these data to previous work identified 10 genes regulated in opposite directions by equol compared to presence of atherosclerosis plaque (Menopause 2011; 18:1087-1095) and 55 genes differentially expressed in the same direction in response to both equol and estradiol (Eyster et al., Menopause 2014;21:143-152.).

CONCLUSIONS

Similar responses of genes to both equol and estradiol may reflect the extent to which equol serves as a natural selective estrogen receptor modulator in the arteries. Opposite responses of 10 genes to equol versus the presence of atherosclerosis implicates those genes in the potential protective effects of equol in arteries.

Effect of isoflavone soy protein supplementation on endometrial thickness, hyperplasia, and endometrial cancer risk in postmenopausal women: a randomized controlled trial

OBJECTIVE

This study aims to determine whether long-term isoflavone soy protein (ISP) supplementation affects endometrial thickness and rates of endometrial hyperplasia and cancer in postmenopausal women.

METHODS

In this randomized, double-blind, placebo-controlled trial, 350 postmenopausal women aged 45 to 92 years were randomized to a total daily dose of 154 mg of ISP or a milk protein-matched placebo for a 3-year period. Women with a surgically absent uterus were excluded from the analysis (final study population, N = 224). The main outcome measures were as follows: mean change in endometrial thickness on transvaginal ultrasound from baseline until up to 36 months of follow-up and the incidence of endometrial sampling, endometrial hyperplasia, and endometrial cancer.

RESULTS

A total of 666 visits among 224 participants were evaluated. Treatment groups did not significantly differ on the mean baseline or on-trial changes in endometrial thickness. Of the 103 placebo-treated participants, 7 (6.8%) underwent endometrial biopsy; 6 (85.7%) of these biopsies were benign. One woman in the placebo group was diagnosed with complex endometrial hyperplasia with atypia and underwent hysterectomy. The pathology result from this surgical operation was stage IB endometrial cancer. Of the 121 participants in the soy group, 9 (7.4%) underwent endometrial biopsy. The results were benign in all nine cases (100%). Although the rate of hyperplasia/malignancy was higher in the placebo group (14.3% vs 0%), the difference was not statistically significant.

CONCLUSIONS

Three-year ISP supplementation has no effect on endometrial thickness or on the rates of endometrial hyperplasia and cancer in postmenopausal women.

Effects of bazedoxifene alone and with conjugated equine estrogens on coronary and peripheral artery atherosclerosis in postmenopausal monkeys

OBJECTIVE

The objectives of this study were to evaluate the effects of bazedoxifene acetate (BZA), a new selective estrogen receptor modulator, on coronary and peripheral artery atheroscleroses and to determine if it would antagonize the atheroprotective effects of conjugated equine estrogens (CEE) on a monkey model.

METHODS

Ninety-eight surgically postmenopausal monkeys (Macaca fascicularis) were fed a moderately atherogenic diet and randomized to receive no treatment or women's equivalent doses of BZA (20 mg/d), CEE (0.45 mg/d), or BZA + CEE. The experimental period lasted for 20 months (equivalent to approximately 5 y in humans) during which interim measures of cardiovascular risk factors were made. At the end of the experimental period, the extent and severity of coronary and iliac artery atheroscleroses were quantified.

RESULTS

Body weight, adiposity, fasting glucose concentrations, and plasma lipid profiles were not different among treatment conditions. BZA had no adverse effects on the extent or severity of coronary or common iliac artery atherosclerosis when compared with no treatment. CEE, administered soon after inducing menopause, had robust atheroprotective effects on both the extent and the severity of iliac and coronary artery atheroscleroses. The addition of BZA to CEE treatment antagonized the atheroprotective effects of CEE.

CONCLUSIONS

In this nonhuman primate trial, treatment with BZA alone, CEE alone, and combined BZA and CEE does not have significant effects on plasma lipid profiles. CEE markedly inhibits the progression and complications of both coronary and iliac artery atheroscleroses. BZA has no adverse effects on atherosclerosis but attenuates the atheroprotective effects of CEE.

Premenopausal antimüllerian hormone concentration is associated with subsequent atherosclerosis

OBJECTIVE

The aim of this study was to determine if premenopausal ovarian reserve is associated with susceptibility for atherosclerosis.

METHODS

Female cynomolgus macaques (n = 66, women's equivalent age = 45 y) consumed an atherogenic diet for ∼5 months before the measurement of a marker of ovarian reserve (antimüllerian hormone [AMH]), plasma lipids, follicular phase estradiol, and body weight (BW). Monkeys were then ovariectomized (OVX; n = 17), remained premenopausal (n = 20), or were induced to have reduced ovarian reserve (ROR, n = 29). After 26 additional months consuming the diet, atherosclerosis measurements and risk variables were reassessed.

RESULTS

No differences in baseline AMH, plasma lipids, BW, and estradiol or postdiet lipids and BW were observed among the groups subsequently assigned to the OVX, premenopausal control, or reduced ovarian reserve conditions. Postdiet measurements of atherosclerosis extent did not differ among the groups. However, analysis of plaque size by tertile of baseline AMH revealed that plaques were largest in monkeys that began the experiment with the lowest baseline AMH, followed by those in the middle and high tertiles (plaque extent: low AMH, 0.76 ± 0.12 mm; mid AMH, 0.46 ± 0.1 mm; high AMH, 0.34 ± 0.08 mm; P = 0.02). Baseline AMH and plaque size were also correlated negatively (r = -0.31, P = 0.01). Plasma lipids were also correlated significantly with plaque extent (all P < 0.01) but not with AMH.

CONCLUSIONS

We report for the first time an inverse relationship between a marker of ovarian reserve (AMH) and subsequent atherosclerosis risk.

The quantification of vitamin D receptors in coronary arteries and their association with atherosclerosis

OBJECTIVE

The activated vitamin D receptor (VDR) may have an important role in vascular health. The objective of this study was to determine whether there is an association between the expression of VDRs in coronary arteries and the extent of diet-induced atherosclerosis.

METHODS

Utilizing a cohort of 39 postmenopausal female cynomolgus monkeys with varying stages of atherosclerosis, histologic sections of the left anterior descending artery (LAD) were analyzed for plaque cross-sectional area, plaque thickness, and VDR quantity using immunohistochemical H-score analysis. The quantities of VDRs were analyzed as a continuous variable and were divided at the median intimal H-score into high vs. low groupings.

RESULTS

In the LAD, a significant negative correlation was observed between the quantity of VDR and plaque size (both cross-sectional area [p<0.001] and plaque thickness [p<0.001]). Monkeys in the low VDR group had a significantly greater cross-sectional plaque area (1.2mm(2)) and greater plaque thickness (0.3mm) than those in the high VDR group (0.4mm(2), p=0.005; 0.1mm, p=0.003, respectively).

CONCLUSIONS

Lower concentrations of VDRs in a main coronary artery were associated with greater atherosclerotic plaque size in postmenopausal female monkeys. Given that coronary artery atherosclerosis is a major cause of coronary heart disease in postmenopausal women, further research to ascertain the relationship between VDRs and atherosclerosis is warranted.

Vascular effects of phytoestrogens and alternative menopausal hormone therapy in cardiovascular disease

Phytoestrogens are estrogenic compounds of plant origin classified into different groups including isoflavones, lignans, coumestans and stilbenes. Isoflavones such as genistein and daidzein are the most studied and most potent phytoestrogens, and are found mainly in soy based foods. The effects of phytoestrogens are partly mediated via estrogen receptors (ERs): ERα, ERβ and possibly GPER. The interaction of phytoestrogens with ERs is thought to induce both genomic and non-genomic effects in many tissues including the vasculature. Some phytoestrogens such as genistein have additional non-ER-mediated effects involving signaling pathways such as tyrosine kinase. Experimental studies have shown beneficial effects of phytoestrogens on endothelial cells, vascular smooth muscle, and extracellular matrix. Phytoestrogens may also affect other pathophysiologic vascular processes such as lipid profile, angiogenesis, inflammation, tissue damage by reactive oxygen species, and these effects could delay the progression of atherosclerosis. As recent clinical trials showed no vascular benefits or even increased risk of cardiovascular disease (CVD) and CV events with conventional menopausal hormone therapy (MHT), phytoestrogens are being considered as alternatives to pharmacologic MHT. Epidemiological studies in the Far East population suggest that dietary intake of phytoestrogens may contribute to the decreased incidence of postmenopausal CVD and thromboembolic events. Also, the WHO-CARDIAC study supported that consumption of high soybean diet is associated with lower mortalities from coronary artery disease. However, as with estrogen, there has been some discrepancy between the experimental studies demonstrating the vascular benefits of phytoestrogens and the data from clinical trials. This is likely because the phytoestrogens clinical trials have been limited in many aspects including the number of participants enrolled, the clinical end points investigated, and the lack of long-term follow-up. Further investigation of the cellular mechanisms underlying the vascular effects of phytoestrogens and careful evaluation of the epidemiological evidence and clinical trials of their potential vascular benefits would put forward the use of phytoestrogens as an alternative MHT for the relief of menopausal symptoms and amelioration of postmenopausal CVD.

Coronary artery vitamin D receptor expression and plasma concentrations of 25-hydroxyvitamin D: their association with atherosclerosis

OBJECTIVE

The aim of this study was to analyze coronary artery vitamin D receptor (VDR) expression, the plasma concentrations of 25-hydroxyvitamin D3 (25OHD3), and their relationship with coronary artery atherosclerosis.

METHODS

Premenopausal cynomolgus monkeys were fed atherogenic diets containing the equivalent of 1,000 IU/day of vitamin D3. Protein was derived from casein-lactalbumin (C/L, n = 10), soy protein isolate (soy, n = 10), or a combination (n = 19). After 32 months of consuming the diets, each monkey underwent surgical menopause. After 32 postmenopausal months, coronary atherosclerosis was measured in the left circumflex (LCX) artery and left anterior descending (LAD) artery. VDR expression was determined for the LAD, and 25OHD3 concentrations were assessed.

RESULTS

Both the cross-sectional area of atherosclerotic plaques (in square millimeters) and plaque thickness (in millimeters) in the LCX as well as the LAD arteries were analyzed in these monkeys. Those with higher plasma vitamin D3 concentrations and higher VDR were compared with those with higher plasma 25OHD3 concentrations and lower VDR. Significantly smaller plaque sizes were noted with higher plasma 25OHD3 concentrations and higher VDR. For the LCX artery, there was also a significantly lower plaque size (both plaque thickness and cross-sectional area) in those with higher quantities of VDR and lower 25OHD3 concentrations versus those with lower quantities of VDR and higher plasma concentrations of 25OHD3 (P = 0.009 and P = 0.040, respectively).

CONCLUSIONS

Cynomolgus monkeys with higher quantities of VDR have significantly less atherosclerosis than do those with lower quantities of VDR and higher plasma 25OHD3 concentrations. If these findings translate to human beings, it might explain why some individuals with higher plasma concentrations of 25OHD3 have more coronary artery atherosclerosis.

Gene expression signatures differ with extent of atherosclerosis in monkey iliac artery

OBJECTIVE

The aim of this study was to evaluate global gene expression patterns in the common iliac arteries of monkeys with a varied extent of atherosclerosis.

METHODS

The left common iliac artery was removed from ovariectomized cynomolgus monkeys (n = 12) after 6.5 years of consuming a diet containing fat and cholesterol at levels comparable with those consumed in Western populations. Arterial gene expression was analyzed using DNA microarray and real-time reverse transcription-polymerase chain reaction.

RESULTS

Significant differential expression of 986 genes was observed in iliac arteries containing moderate to large atherosclerotic plaques compared with normal/minimally affected reference group arteries. Atherosclerosis-associated genes included cytokines, chemokines, components of signal transduction pathways, and transcriptional activators and repressors, as well as other functional categories. Real-time reverse transcription-polymerase chain reaction confirmed a differential expression of genes chosen from a variety of functional categories. Specifically, the expression of genes for estrogen receptor-1, claudin 11, and brain heart protocadherin 7 was reduced, whereas the expression of genes for apolipoprotein E, growth differentiation factor 15, superoxide dismutase-2, SET domain bifurcated 2, phospholipase A2 group IIA, phospholipase A2 group VII, and ring finger protein 149 was increased in atherosclerotic arteries.

CONCLUSIONS

The gene expression environment in arteries containing atherosclerotic plaques is profoundly different from that of relatively unaffected arteries and reflects the cellular and molecular complexity of atherosclerosis and associated arterial remodeling processes.

Strategies and methods to study sex differences in cardiovascular structure and function: a guide for basic scientists

Background

Cardiovascular disease remains the primary cause of death worldwide. In the US, deaths due to cardiovascular disease for women exceed those of men. While cultural and psychosocial factors such as education, economic status, marital status and access to healthcare contribute to sex differences in adverse outcomes, physiological and molecular bases of differences between women and men that contribute to development of cardiovascular disease and response to therapy remain underexplored.

Methods

This article describes concepts, methods and procedures to assist in the design of animal and tissue/cell based studies of sex differences in cardiovascular structure, function and models of disease.

Results

To address knowledge gaps, study designs must incorporate appropriate experimental material including species/strain characteristics, sex and hormonal status. Determining whether a sex difference exists in a trait must take into account the reproductive status and history of the animal including those used for tissue (cell) harvest, such as the presence of gonadal steroids at the time of testing, during development or number of pregnancies. When selecting the type of experimental animal, additional consideration should be given to diet requirements (soy or plant based influencing consumption of phytoestrogen), lifespan, frequency of estrous cycle in females, and ability to investigate developmental or environmental components of disease modulation. Stress imposed by disruption of sleep/wake cycles, patterns of social interaction (or degree of social isolation), or handling may influence adrenal hormones that interact with pathways activated by the sex steroid hormones. Care must be given to selection of hormonal treatment and route of administration.

Conclusions

Accounting for sex in the design and interpretation of studies including pharmacological effects of drugs is essential to increase the foundation of basic knowledge upon which to build translational approaches to prevent, diagnose and treat cardiovascular diseases in humans.

Isoflavone soy protein supplementation and atherosclerosis progression in healthy postmenopausal women: a randomized controlled trial

BACKGROUND AND PURPOSE

Although epidemiological and experimental studies suggest that dietary intake of soy may be cardioprotective, use of isoflavone soy protein (ISP) supplementation as a primary preventive therapy remains unexplored. We determined whether ISP reduces subclinical atherosclerosis assessed as carotid artery intima-media thickness progression.

METHODS

In a double-blind, placebo-controlled trial, 350 postmenopausal women 45 to 92 years of age without diabetes and cardiovascular disease were randomized to 2 evenly divided daily doses of 25 g soy protein containing 91 mg aglycon isoflavone equivalents or placebo for 2.7 years.

RESULTS

Overall, mean (95% CI) carotid artery intima-media thickness progression rate was 4.77 (3.39-6.16) μm/year in the ISP group and 5.68 (4.30-7.06) μm/year in the placebo group. Although carotid artery intima-media thickness progression was reduced on average by 16% in the ISP group relative to the placebo group, this treatment effect was not statistically significant (P=0.36). Among the subgroup of women who were randomized within 5 years of menopause, ISP participants had on average a 68% lower carotid artery intima-media thickness progression rate than placebo participants 2.16 (-1.10 to 5.43) versus 6.79 (3.56-10.01) μm/year (P=0.05). ISP supplementation had a null effect on women who were >5 years beyond menopause when randomized. There were no major adverse events from ISP supplementation.

CONCLUSIONS

ISP supplementation did not significantly reduce subclinical atherosclerosis progression in postmenopausal women. Subgroup analysis suggests that ISP supplementation may reduce subclinical atherosclerosis in healthy young (median age, 53 years) women at low-risk for cardiovascular disease who were <5 years postmenopausal. These first trial results of their kind warrant further investigation.

Identification of a mechanism for increased cardiovascular risk among individuals with low vitamin D concentrations

OBJECTIVE

The aim of this study was to investigate the plasma concentrations of vitamin D and its association with plasma lipid profiles.

METHODS

Plasma vitamin D3 and lipid concentrations were measured in 119 female cynomolgus monkeys (premenopausal, n = 49; ovariectomized, n = 70) consuming approximately 1,000 IU per day of vitamin D3. In a subset of the ovariectomized monkeys (n = 23), vitamin D3 was remeasured after 6 months. The concentrations of vitamin D3 were analyzed as a continuous variable and were divided at the median into high (≥48 ng/mL) versus low (<48 ng/mL) groupings.

RESULTS

Among the 119 monkeys, the range of vitamin D3 concentrations was 24.0 to 95.2 ng/mL (mean ± SD, 48.5 ± 12.7 ng/mL). Plasma vitamin D3 concentration was positively associated with high-density lipoprotein cholesterol (HDL-C; P = 0.003). Monkeys in the high vitamin D3 group had a significantly greater plasma HDL-C concentration (57.9 mg/dL) than did those in the low vitamin D3 group (47.1 mg/dL; P = 0.001). Although the difference was not significant (P = 0.120), the monkeys in the high vitamin D3 group had a decreased total plasma cholesterol-to-HDL-C ratio compared with those in the low vitamin D3 group (5.4 and 6.2, respectively), potentially putting them at lower risk of atherosclerosis development.

CONCLUSIONS

Given that the monkeys all consumed a diet replete in vitamin D3, it seems that individual differences in vitamin D absorption or metabolism may have determined whether the monkeys had high or low concentrations of vitamin D3. Lower vitamin D3 was associated with a more atherogenic lipid profile, a major risk factor for progressing to coronary artery atherosclerosis in monkeys and human beings.

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.

Timing and duration of menopausal hormone treatment may affect cardiovascular outcomes

Largely on the basis of the first publication of findings of net harm with menopausal hormone treatment in the Women's Health Initiative (WHI) hormone trials, current Food and Drug Administration recommendations limit menopausal hormone treatment to the "…shortest duration consistent with treatment goals…," with goals generally taken to mean relief of menopausal symptoms and maximal duration as approximately 5 years. The WHI finding of net harm was due largely to the absence of beneficial effects on coronary heart disease incidence rates. Published analyses of WHI data by age or time since menopause find that excess coronary heart disease risk with menopausal hormone treatment is confined to more remotely menopausal or older women, with younger women showing nonsignificant trends toward benefit (the "timing hypothesis"). Moreover, a recently published reexamination of data from the WHI Estrogen plus Progestin trial suggests that reduced coronary heart disease risk may appear only after 5 to 6 years of treatment. Consistent with this finding, risk ratios for coronary heart disease were calculated as 1.08 (95% confidence interval, 0.86-1.36) in years 1 to 6 and as 0.46 (confidence interval, 0.28-0.78) in years 7 to 8+ in the WHI Estrogen Alone trial. Previous studies also support the beneficial effects of menopausal hormone treatment after prolonged exposure. Thus, current analyses do not support a generalized recommendation for short duration of menopausal hormone treatment. Rather, they suggest that current Food and Drug Administration practice guidelines should be reconsidered to allow individualized care based on risk:benefit considerations. New research is urgently needed evaluating influences of timing, duration, dose, route of administration, and agents on menopausal hormone treatment-related risks and benefits to better understand how to optimize recommendations for individual patients.

Primate models in women's health: inflammation and atherogenesis in female cynomolgus macaques (Macaca fascicularis)

Female cynomolgus monkeys are excellent models for understanding cardiovascular disease and the relationships between inflammatory processes and conditions such as atherogenesis. This review summarizes published research findings obtained through comprehensive, multidisciplinary, multi-investigator studies in nonhuman primates over the past two decades. These studies examined the effects of exogenous estrogens and dietary soy protein/isoflavones (IFs) on atherosclerosis, circulating biomarkers, and tissue inflammation in pre- and postmenopausal female cynomolgus monkeys. Inflammation may play a role in the initiation and progression of disease, be a consequence of the disease, or both. Circulating and tissue biomarkers with inflammatory and anti-inflammatory characteristics (including adhesion molecules such as e-selectin, VCAM-1, and ICAM-1, chemokines such as MCP-1, cytokines such as interleukins, and acute phase reactants such as CRP, and others) may be useful indicators of disease status. Treatment of postmenopausal subjects with estrogen resulted in significant reductions in several key inflammatory mediators as well as atherosclerosis, while dietary IF had a more limited effect on inflammation and atherogenesis. Circulating concentrations of key inflammatory proteins, including monocyte-chemoattractant protein-1 (MCP-1) and interleukin-6 (IL-6), were associated with atherosclerosis and lesion characteristics in these animals. In premenopausal female monkeys, a diet enriched in soy protein reduced arterial inflammation as well as atherogenesis in comparison to a diet enriched in casein-lactalbumin. Expression levels of arterial inflammation associated genes (MCP-1, ICAM-1) and markers for inflammatory cell types (macrophages and T cells) correlated with plaque size, were differentially influenced by treatments, and represent potential targets for interventions. Arterial expression of estrogen receptor alpha, the key mediator of estrogenic effects, was inversely correlated with plaque size and indices of inflammation, suggestive of an atheroprotective role. The findings provide additional evidence that circulating inflammatory markers (particularly MCP-1) may be useful indicators of atherosclerotic disease progression and responses to treatment in female primates, and that estrogens and dietary soy may inhibit atherogenesis in part through anti-inflammatory mechanisms.

The relationship between social status and atherosclerosis in male and female monkeys as revealed by meta-analysis

More than 25 years ago our laboratory reported sex-dependent relationships between social status and coronary artery atherosclerosis among cholesterol-fed cynomolgus monkeys (Macaca fascicularis) maintained in social groups of four to six animals each. Dominant males developed more atherosclerosis than subordinates, but only if housed in recurrently reorganized social groups. In contrast, dominant females developed significantly less atherosclerosis than subordinates, irrespective of social setting. Although we have continued to study these associations, no confirmatory investigations have been reported by other laboratories or using other atherosclerosis-susceptible monkey species. Accordingly, we conducted a meta-analysis of all relevant data sources developed in our laboratory since 1982 to determine whether the originally reported relationships between social status and atherosclerosis reflected robust associations. The sentinel (first) studies were composed of 16 females and 27 males. The current meta-analysis encompassed 419 animals (200 females and 219 males) derived from 11 separate investigations. The results confirmed that, among males, dominant individuals developed more extensive atherosclerosis than subordinates when housed in recurrently reorganized (unstable) social groups in which an estrogen-implanted female was also present. Dominant males in stable social groups tended to have less atherosclerosis than similarly housed subordinates, but this effect was not significant. On the contrary, we found that dominant females developed reliably less atherosclerosis than subordinates.

Plasma lipid-dependent and -independent effects of dietary soy protein and social status on atherogenesis in premenopausal monkeys: implications for postmenopausal atherosclerosis burden

OBJECTIVE

: Atherosclerosis developed during premenopausal years predicts postmenopausal atherosclerosis burden. The objective of this study was to determine the effects of dietary soy protein isolate (SPI) and social status on atherogenesis and arterial gene expression in a premenopausal monkey model.

DESIGN

: Socially housed premenopausal cynomolgus macaques (n = 84) were fed an atherogenic diet deriving protein from casein/lactalbumin or SPI (containing 1.88 mg isoflavones/g). After 36 months of diet consumption, iliac artery biopsies were assessed for atherosclerosis and expression of mRNA transcripts related to inflammation, macrophage and T-cell content, and estrogen receptors (ERs).

RESULTS

: SPI reduced plaque size (P < 0.05), total plasma cholesterol, non-high-density lipoprotein cholesterol (HDLc), and the total plasma cholesterol/HDLc ratio (all P < 0.003), while increasing triglycerides (P < 0.006) and HDLc (P < 0.0001). Arterial mRNA for CD68 (P < 0.001), CD3 (P < 0.02), and CD4 (P < 0.001) and inflammatory markers monocyte chemotactic protein-1, intercellular adhesion molecule-1, and interleukin-6 (all P < 0.0001) were also lower in the group receiving SPI. For most outcomes, this effect remained even after adjustments for plaque size and plasma lipid concentrations. Arterial ER-alpha was inversely associated with atherosclerosis (P < 0.02) and increased with SPI (P < 0.001). Subordinate monkeys had lower ER-beta (P < 0.02) and higher interleukin-6 (P < 0.05) transcripts but did not differ from dominant monkeys in extent of atherosclerosis (P > 0.9).

CONCLUSIONS

: Premenopausal consumption of SPI had plasma lipid-independent beneficial effects on the pathobiological processes involved in atherosclerotic plaque development, thus potentially establishing the basis for reduced postmenopausal complications. Dominant social status provided similar, albeit less extensive, benefits in risk markers.

Past oral contraceptive use and current dietary soy isoflavones influence estrogen metabolism in postmenopausal monkeys (Macaca fascicularis)

Estrogen metabolism may play an important role in mammary carcinogenesis in postmenopausal women. We evaluated the effects of prior oral contraceptive (OC) treatment and current soy isoflavone consumption on endogenous estrogen metabolite concentration and biomarkers of tissue estrogen exposure in a monkey model. One hundred eighty-one female cynomolgus macaques were randomized to receive OC or placebo for 26 months premenopausally, then ovariectomized and randomized to one of three diets for 36 months: an isoflavone-depleted soy protein isolate (Soy-) diet, a diet containing soy protein isolate with a human equivalent of 129 mg isoflavone/d (Soy+), or a Soy- diet supplemented with conjugated equine estrogens (CEE+) at a human equivalent dose of 0.625 mg/d. Reverse-phase high-performance liquid chromatography directly coupled with tandem mass spectrometry was used to measure the concentrations of estrogen species in urine samples. Generally, prior OC treatment was associated with significantly reduced urinary estrogen metabolites (25-55% reduction; P<0.05 for each versus OC-). Animals that consumed isoflavones postmenopausally had increased urinary 2-hydroxyestrone and 16alpha-hydroxyestrone (50% and 56% increases, respectively), but reduced levels of 2-hydroxyestradiol, 2-methoxyestradiol, and 17-epiestriol (92%, 63%, and 66%, respectively), compared with animals fed a Soy- diet. Isoflavones did not have widespread effects on uterine or mammary proliferation biomarkers, whereas prior OC significantly reduced two of three proliferation end points in the endometrium. Premenopausal OCs may have long-term systemic effects on response to estrogen and its metabolism whereas postmenopausal dietary isoflavones may alter endogenous estrogen metabolism in a modest but selective manner.

Effects of prior oral contraceptive use and soy isoflavonoids on estrogen-metabolizing cytochrome P450 enzymes

Estrogen exposure and metabolism may play an important role in the development of estrogen-sensitive cancers in postmenopausal women. In this study we investigated whether past oral contraceptive (OC) administration or current dietary isoflavonoids (IF) affected expression and/or activity of steroid hormone-metabolizing cytochrome P450 (CYP) enzymes using complementary primate and cell culture models. One-hundred-eighty-one female cynomolgus macaques were randomized to receive OC or nothing for 26 months premenopausally, then ovariectomized and randomized to one of three diets for 36 months: an IF-depleted soy protein isolate (Soy-) diet, a Soy diet with IF (Soy+), or a Soy- diet supplemented with conjugated equine estrogens (CEE). Prior OC-treatment significantly reduced CYP gene expression in the mammary gland (< or =60% of OC-). Dietary IFs had no effect on CYP expression, while CEE-treatment decreased CYP1A1 and increased CYP3A4 mRNA in a tissue-specific manner. For in vitro studies, we measured effects of the isoflavonoids genistein, daidzein and equol on CYP activity using intact V79 cells stably transfected to express CYP1A1, CYP1B1, or CYP3A4. All three IFs significantly altered CYP activity in a dose-dependent and isoform-specific manner (20-95% inhibition versus controls). These results suggest potential mechanisms for prior OC and dietary IF effects on cancer risk in estrogen-responsive tissues.

Effects of botanical dietary supplements on cardiovascular, cognitive, and metabolic function in males and females

BACKGROUND

The onset of menopause marks a pivotal time in which the incidence of hypertension and of cardiovascular disease (CVD) begins to increase dramatically in women. Before menopause, the incidences of these diseases are significantly lower in women than in age-matched men. After menopause, the rates of these diseases in women eventually approximate those in men. The loss of endogenous estrogen at menopause has been traditionally believed to be the primary factor involved in these changes.

OBJECTIVE

This review summarizes recent findings regarding the effectiveness of botanicals in the treatment of some menopausal symptoms and other symptoms of aging (eg, rise in arterial pressure, cognitive decline, insulin resistance, and hyperlipidemia).

METHODS

Articles were selected for inclusion in this review based on the significance of the research and contribution to the current understanding of how each botanical elicits cardioprotective effects. To this end, PubMed and MEDLINE databases were searched, using terms that included the name of the specific botanical along with the relevant aspects of its action(s), such as blood pressure, glycemic control, and lipids. Most of the articles used were published within the past 5 years, although some older articles that were seminal in advancing the current understanding of botanicals were also included.

RESULTS

Soy has been found to lower plasma lipid concentrations and arterial pressure in postmenopausal women and age-matched men, and to have protective effects in heart disease and atherosclerosis of the carotid and coronary circulation. Soy was also found to lower fasting insulin concentrations and glycosylated hemoglobin concentrations. Grape seed extract, another frequently used botanical, contains polyphenols that have been found to reduce arterial pressure and salt-sensitive hypertension in estrogendepleted animal models.

CONCLUSION

Several botanical compounds have been found to have beneficial effects in the treatment of the symptoms of menopause and other symptoms of aging, including CVD, cognitive decline, and metabolic diseases.

Soy-tibolone combination - effect on lipids in postmenopausal monkeys and women

OBJECTIVES

To determine whether co-administration of soy during tibolone treatment would prevent tibolone-induced dyslipoproteinemia in postmenopausal monkeys and women.

METHODS

Surgically postmenopausal cynomolgus monkeys (n = 18) were assigned randomly to one of four dietary regimens in a Latin Square crossover design, such that all animals received all diets for 14 weeks with a 4-week washout period: (1) casein/lactalbumin (CL); (2) tibolone (Tib, 1.25 mg/day women's equivalent); (3) soy (138 mg isoflavones/day women's equivalent); (4) Soy + Tib. Postmenopausal women on tibolone treatment were randomized to receive soy powder (52 g of soy protein containing 112 mg isoflavones) or placebo (containing 52 g of milk protein) daily in a crossover trial for 8 weeks with a 4-week washout period.

RESULTS

Monkeys given Tib alone had approximately 14% increase in plasma LDL + VLDL-C; whereas those given soy combined with tibolone had significant ( approximately 22%) reductions. Tib treated monkeys had reductions in plasma HDL-C of about 48% vs. no reductions in Soy + Tib. In postmenopausal women using tibolone, soy reduced plasma LDL-C concentrations by approximately 10% from baseline without a change in HDL-C.

CONCLUSIONS

Co-administration of soy during tibolone treatment improved the lipoprotein profile in both monkeys and women; however, the effects were more robust in monkeys.

Effects of long-term estrogen replacement therapy on bone turnover in periarticular tibial osteophytes in surgically postmenopausal cynomolgus monkeys

The aims of the present study were to assess the effects of long-term estrogen replacement therapy (ERT) on size and indices of bone turnover in periarticular osteophytes in ovariectomized cynomolgus monkeys and to compare dynamic indices of bone turnover in osteophyte bone with those of subchondral bone (SCB) and epiphyseal/metaphyseal cancellous (EMC) bone. One hundred sixty-five adult female cynomolgus macaques were bilaterally ovariectomized and randomly divided into three age- and weight-matched treatment groups for a 36-month treatment period. Group 1 (OVX control) received no treatment, Group 2 (SPE) received soy phytoestrogens, and Group 3 (ERT) received conjugated equine estrogens in the diet; all monkeys were labeled with calcein before necropsy. A midcoronal, plastic-embedded section of the right proximal tibia from 20 randomly selected animals per treatment group was examined histologically. Forty-nine of the sections (OVX control, n=16; SPE, n=16; ERT, n=17) contained lateral abaxial osteophytes, and static and dynamic histomorphometry measurements were taken from osteophyte bone, SCB from the lateral tibial plateau, and EMC bone. Data were analyzed using the ANOVA and Kruskal-Wallis test, correlation and regression methods, and the Friedman and Wilcoxon signed rank test. There was no significant effect of long-term ERT on osteophyte area or on any static or dynamic histomorphometry parameters. The bone volume, trabecular number, and trabecular thickness in osteophyte bone were considerably higher than in EMC bone; whereas, trabecular separation was considerably lower in osteophyte bone. In all three treatment groups, BS/BV was significantly lower in osteophyte bone vs. EMC bone and significantly higher in osteophyte bone vs. lateral SCB. We conclude that osteophyte area and static and dynamic histomorphometry parameters within periarticular tibial osteophytes in ovariectomized cynomolgus monkeys are not significantly influenced by long-term ERT, but that site differences in static and dynamic bone histomorphometry parameters exist, particularly between EMC and osteophyte bone.

Effects of long-term estrogen replacement therapy on the prevalence and area of periarticular tibial osteophytes in surgically postmenopausal cynomolgus monkeys

Osteoarthritis (OA) occurs naturally in cynomolgus macaques. The purposes of the present study were to: 1) develop histological measurement schemes to measure the cross-sectional area of axial and abaxial osteophytes in the proximal tibia; 2) determine the effects of long-term estrogen replacement therapy (ERT) on osteophyte prevalence and area; and 3) assess relationships between osteophyte size and risk factors of OA (age and body weight) and concurrent bone and cartilage lesions. Adult female cynomolgus macaques (n=180) were bilaterally ovariectomized (OVX) and were treated for 3 years with ERT, soy phytoestrogens (SPE), or no hormones (OVX controls). At necropsy, the prevalence and cross-sectional area of periarticular tibial osteophytes were evaluated histologically. Treatment effects on osteophyte prevalence and area were evaluated using Chi-square analyses and Kruskal-Wallis test, respectively; other comparisons were evaluated using regression analyses. The prevalence of abaxial osteophytes in the medial tibial plateau was not significantly affected by treatment group; however, the prevalence of abaxial osteophytes in the lateral tibial plateau was significantly lower in ERT group than SPE group (p<0.01). The total number of abaxial osteophytes (sum of lateral and medial) was significantly lower in ERT group compared to OVX and SPE groups. Neither the prevalence of axial osteophytes nor the sum of lateral and medial axial osteophytes was significantly affected by treatment in either tibial plateau. There were no significant treatment effects on axial or abaxial osteophyte cross-sectional area in either tibial plateau. There was a significant positive correlation between abaxial osteophyte area and SCB thickness in the medial tibial plateau (p=0.048); however, there were no significant correlations between abaxial osteophyte area (medial or lateral) and age or body weight. In this model of naturally occurring OA, long-term ERT does not consistently reduce the prevalence, and has no significant effects on cross-sectional area, of periarticular tibial osteophytes.

Effects of dietary soy protein on iliac and carotid artery atherosclerosis and gene expression in male monkeys

Male cynomolgus macaques (n=91) consumed an isoflavone (IF)-free, atherogenic control diet containing casein/lactalbumin for 5 months, then were randomized to three groups: control (n=30) continued on the control diet; low IF (n=30) received a mixture of unmodified and IF-depleted soy protein isolate (SPI) (0.94 mg IF/g protein, approximating a human intake of 75 mg/day); high IF (n=31) received unmodified SPI (1.88 mg IF/g protein, approximating a human intake of 150 mg/day) for 31 months. Iliac and carotid artery atherosclerosis, and arterial and hepatic mRNA transcripts related to inflammation and estrogen receptors (ER) were measured. Trend analysis identified a significant inverse relationship between dietary IF content and plaque area in the iliac (p<0.05) but not carotid arteries (p>0.13). No significant effect of diet on inflammatory gene or estrogen receptor expression was observed. Plaque area was positively correlated with the mRNA transcript levels for arterial MCP-1, ICAM-1, and the macrophage marker CD68 (all r>0.25, p<0.03), and negatively correlated with ER alpha and ER beta (all r<-0.23, p<0.03). Coronary artery plaque area appeared to be more closely associated with gene expression patterns of the iliac arteries than the carotid arteries. The data suggests benefits of dietary soy on atherosclerotic plaque development in males may be mediated through inflammation-independent pathways. The negative associations of arterial ER alpha expression with atherosclerosis lend support to a mechanistic role for estrogen receptors in atherosclerosis susceptibility which merits further study.

Assessment of soy phytoestrogens' effects on bone turnover indicators in menopausal women with osteopenia in Iran: a before and after clinical trial

BACKGROUND

Osteoporosis is the gradual declining in bone mass with age, leading to increased bone fragility and fractures. Fractures in hip and spine are known to be the most important complication of the disease which leads in the annual mortality rate of 20% and serious morbidity rate of 50%. Menopause is one of the most common risk factors of osteoporosis. After menopause, sex hormone deficiency is associated with increased remodeling rate and negative bone balance, leading to accelerated bone loss and micro-architectural defects, resulting into increased bone fragility. Compounds with estrogen-like biological activity similar to "Isoflavones" present in plants especially soy, may reduce bone loss in postmenopausal women as they are similar in structure to estrogens. This research, therefore, was carried out to study the effects of Iranian soy protein on biochemical indicators of bone metabolism in osteopenic menopausal women.

MATERIALS AND METHODS

This clinical trial of before-after type was carried out on 15 women 45-64 years of age. Subjects were given 35 g soy protein per day for 12 weeks. Blood and urine sampling, anthropometric measurement and 48-h-dietary recalls were carried out at zero, 6 and 12 weeks. Food consumption data were analyzed using Food Proccessor Software. For the study of bone metabolism indicators and changes in anthropometric data as well as dietary intake, and repeated analyses were employed.

RESULTS

Comparison of weight, BMI, physical activity, energy intake and other intervening nutrients did not reveal any significant changes during different stages of the study. Soy protein consumption resulted in a significant reduction in the urinary deoxypyridinoline and increasing of total alkaline phosphatase (p < 0.05), although the alterations in osteocalcin, c-telopeptide, IGFBP3 and type I collagen telopeptide were not significant.

CONCLUSION

In view of beneficial effect of soy protein on bone metabolism indicators, inclusion of this relatively inexpensive food in the daily diet of menopausal women, will probably delay bone resorption, thereby preventing osteoporosis.

Is the WHI relevant to HRT started in the perimenopause?

The Women's Health Initiative (WHI) hormone replacement therapy (HRT) estrogen plus progestin (E+P) and estrogen-only arms are part of a large NIH-sponsored randomized controlled trial (RCT). Both arms were terminated prematurely after 5 and 8 yr, respectively. The E+P arm showed non-statistically significant increased incidences of cardiovascular events and breast cancer, whereas the E-only arm did not. Both arms showed an increased rate of thromboembolic events and stroke. Both arms showed protection against fractures and with protection against colon cancer only in the E+P arm. These results have been widely generalized as indicating a negative risk/benefit ratio for HRT in menopausal women. The WHI results are at odds with results of large epidemiological studies that showed protection against cardiovascular disease. Although the latter data are, in part, confounded by a "healthy user bias," much of the inconsistency may be explained by the fact that women in the latter studies initiated HRT at the menopausal transition, whereas the WHI trial was conducted in older women (mean age 63.3), who were, on average, approx 12 yr postmenopausal. In addition, older trials included women on either unopposed estrogen therapy (ERT) or cyclic HRT regimens. Whatever other forces may have been at work, observational and experimental evidence supports the conclusion that estrogen's atheropreventive effects predominate early, in the absence of vulnerable plaque to be ruptured or thrombotic episodes propagated by narrowed lumens and intravascular turbulence. On the contrary, age-related adverse effects of HRT may prevail once complex atheromas and luminal narrowing/irregularity are established. It is known that prevalence of subclinical "at-risk" atherosclerotic lesions increases in women during the first 5-10 yr after menopause. Furthermore, animal and clinical evidence supports the use of lower doses of estrogen than were employed in the WHI in older/longer postmenopausal women.

Prevention of coronary hyperreactivity in preatherogenic menopausal rhesus monkeys by transdermal progesterone

OBJECTIVE

To test if transdermal progesterone (P) confers coronary vascular protection in surgically menopausal preatherosclerotic rhesus monkeys.

METHODS AND RESULTS

Ovariectomized rhesus monkeys fed an atherogenic diet (AD) for 19 months were treated with an investigational transdermal P cream (n=7) or identical placebo cream (n=5) for 4 weeks. Aorta and carotids showed fatty streaks and Oil Red O staining demonstrated lipid deposition. Serum P levels in P-treated rhesus monkeys (0.6 ng/mL) were significantly greater than placebo (0.2 ng/mL). Significant elevation of cholesterol, LDL cholesterol, and HDL cholesterol, was noted in all animals. Lp(a) was significantly attenuated in the AD-fed P-treated monkeys. Coronary angiographic experiments stimulating vasoconstriction by intracoronary injections of serotonin plus U46619 showed exaggerated prolonged actions amplified by AD, but significant protection against severe prolonged vasoconstriction in P-treated monkeys. Immunocytochemistry confirmed co-expression of P and thromboxane prostanoid (TP) receptors in coronaries and aorta. Western blotting demonstrated TP receptor attenuation in vascular muscle after P treatment.

CONCLUSIONS

Coronary hyperreactivity, a putative component of coronary artery disease mediated via increased vascular muscle thromboxane prostanoid receptors, can be prevented by subphysiological levels of P, not only in nonatherosclerotic (previously shown) but also in preatherosclerotic primates.

Effects of isoflavones (soy phyto-estrogens) on serum lipids: a meta-analysis of randomized controlled trials

Objectives

To determine the effects of isoflavones (soy phyto-estrogens) on serum total cholesterol (TC), low density lipoprotein cholesterol (LDL), high density lipoprotein cholesterol (HDL) and triglyceride (TG).

Methods

We searched electronic databases and included randomized trials with isoflavones interventions in the forms of tablets, isolated soy protein or soy diets. Review Manager 4.2 was used to calculate the pooled risk differences with fixed effects model.

Results

Seventeen studies (21 comparisons) with 853 subjects were included in this meta-analysis. Isoflavones tablets had insignificant effects on serum TC, 0.01 mmol/L (95% CI: -0.17 to 0.18, heterogeneity p = 1.0); LDL, 0.00 mmol/L (95% CI: -0.14 to 0.15, heterogeneity p = 0.9); HDL, 0.01 mmol/L (95% CI: -0.05 to 0.06, heterogeneity p = 1.0); and triglyceride, 0.03 mmol/L (95% CI: -0.06 to 0.12, heterogeneity p = 0.9). Isoflavones interventions in the forms of isolated soy protein (ISP), soy diets or soy protein capsule were heterogeneous to combine.

Conclusions

Isoflavones tablets, isolated or mixtures with up to 150 mg per day, seemed to have no overall statistical and clinical benefits on serum lipids. Isoflavones interventions in the forms of soy proteins may need further investigations to resolve whether synergistic effects are necessary with other soy components.

What is the cardioprotective role of hormone replacement therapy?

A very large body of literature has yielded strong biologic and mechanistic plausibility for the consistent observational findings that estrogen is cardioprotective. Recently completed randomized, controlled trials have been interpreted as challenging the doctrine that hormone replacement is cardioprotective for postmenopausal women. However, other than the Estrogen in the Prevention of Atherosclerosis Trial, none of the currently completed (and no ongoing) randomized, controlled trials have appropriately tested the hypothesis generated from observational data that estrogen replacement is cardioprotective. This mainly results from the fact that randomized, controlled trials have not tested the same pattern and type of hormone use in the same population of women observed in the epidemiologic studies. On the other hand, recently completed randomized, controlled trials provide important but limited information concerning the clinical use of a specific regimen of hormone replacement for the prevention of cardiovascular disease in a particular population of postmenopausal women. Observations made from epidemiologic studies will have to be appropriately tested in randomized, controlled trials before any real conclusions can be drawn as to whether hormone replacement is cardioprotective.