Effects of hormone replacement therapy on plaque stability, inflammation, and fibrinolysis in hypertensive or overweight postmenopausal women

Estrogen Receptor Subtypes Elicit a Distinct Gene Expression Profile of Endothelial-Derived Factors Implicated in Atherosclerotic Plaque Vulnerability

In the presence of established atherosclerosis, estrogens are potentially harmful. MMP-2 and MMP-9, their inhibitors (TIMP-2 and TIMP-1), RANK, RANKL, OPG, MCP-1, lysyl oxidase (LOX), PDGF-β, and ADAMTS-4 play critical roles in plaque instability/rupture. We aimed to investigate (i) the effect of estradiol on the expression of the abovementioned molecules in endothelial cells, (ii) which type(s) of estrogen receptors mediate these effects, and (iii) the role of p21 in the estrogen-mediated regulation of the aforementioned factors. Human aortic endothelial cells (HAECs) were cultured with estradiol in the presence or absence of TNF-α. The expression of the aforementioned molecules was assessed by qRT-PCR and ELISA. Zymography was also performed. The experiments were repeated in either ERα- or ERβ-transfected HAECs and after silencing p21. HAECs expressed only the GPR-30 estrogen receptor. Estradiol, at low concentrations, decreased MMP-2 activity by 15-fold, increased LOX expression by 2-fold via GPR-30, and reduced MCP-1 expression by 3.5-fold via ERβ. The overexpression of ERα increased MCP-1 mRNA expression by 2.5-fold. In a low-grade inflammation state, lower concentrations of estradiol induced the mRNA expression of MCP-1 (3.4-fold) and MMP-9 (7.5-fold) and increased the activity of MMP-2 (1.7-fold) via GPR-30. Moreover, p21 silencing resulted in equivocal effects on the expression of the abovementioned molecules. Estradiol induced different effects regarding atherogenic plaque instability through different ERs. The balance of the expression of the various ER subtypes may play an important role in the paradoxical characterization of estrogens as both beneficial and harmful.

Sex Differences in the Inflammatory Response: Pharmacological Opportunities for Therapeutics for Coronary Artery Disease

Coordinated molecular responses are key to effective initiation and resolution of both acute and chronic inflammation. Vascular inflammation plays an important role in initiating and perpetuating atherosclerotic disease, specifically at the site of plaque and subsequent fibrous cap rupture. Both men and women succumb to this disease process, and although management strategies have focused on revascularization and pharmacological therapies in the acute situation to reverse vessel closure and prevent thrombogenesis, data now suggest that regulation of host inflammation may improve both morbidity and mortality, thus supporting the notion that prevention is better than cure. There is a clear sex difference in the incidence of vascular disease, and data confirm biological differences in inflammatory initiation and resolution between men and women. This article reviews contemporary opinions describing the sex difference in the initiation and resolution of inflammatory responses, with a view to explore potential targets for pharmacological intervention.

Estrogen signaling in metabolic inflammation

There is extensive evidence supporting the interference of inflammatory activation with metabolism. Obesity, mainly visceral obesity, is associated with a low-grade inflammatory state, triggered by metabolic surplus where specialized metabolic cells such as adipocytes activate cellular stress initiating and sustaining the inflammatory program. The increasing prevalence of obesity, resulting in increased cardiometabolic risk and precipitating illness such as cardiovascular disease, type 2 diabetes, fatty liver, cirrhosis, and certain types of cancer, constitutes a good example of this association. The metabolic actions of estrogens have been studied extensively and there is also accumulating evidence that estrogens influence immune processes. However, the connection between these two fields of estrogen actions has been underacknowledged since little attention has been drawn towards the possible action of estrogens on the modulation of metabolism through their anti-inflammatory properties. In the present paper, we summarize knowledge on the modification inflammatory processes by estrogens with impact on metabolism and highlight major research questions on the field. Understanding the regulation of metabolic inflammation by estrogens may provide the basis for the development of therapeutic strategies to the management of metabolic dysfunctions.

Matrix metalloproteinases in coronary artery disease

Matrix metalloproteinases (MMP) are a family of zinc-containing endoproteinases that degrade extracellular matrix (ECM) components. MMP have important roles in the development, physiology and pathology of cardiovascular system. Metalloproteases also play key roles in adverse cardiovascular remodeling, atherosclerotic plaque formation and plaque instability, vascular smooth muscle cell (SMC) migration and restenosis that lead to coronary artery disease (CAD), and progressive heart failure. The study of MMP in developing animal model cardiovascular systems has been helpful in deciphering numerous pathologic conditions in humans. Increased peripheral blood MMP-2 and MMP-9 in acute coronary syndrome (ACS) may be useful as noninvasive tests for detection of plaque vulnerability. MMP function can be modulated by certain pharmacological drugs that can be exploited for treatment of ACS. CAD is a polygenic disease and hundreds of genes contribute toward its predisposition. A large number of sequence variations in MMP genes have been identified. Case-control association studies have highlighted their potential association with CAD and its clinical manifestations. Although results thus far are inconsistent, meta-analysis has demonstrated that MMP-3 Glu45Lys and MMP-9 1562C/T gene polymorphisms were associated with CAD risk.

The association of MMP-9 and IL-18 gene promoter polymorphisms with gingivitis in adolescents

OBJECTIVE

Interleukin 18 (IL-18) is shown to be a proinflammatory cytokine that regulates the expression of matrix metalloproteinase 9 (MMP-9). The aim of this study was to test for differences between Czech adolescents with and without gingivitis in relation to MMP-9 and IL-18 polymorphisms.

DESIGN

A total of 298 Caucasian children, aged 11-13 years, were examined to assess gingival health. DNA for genetic analysis was obtained from buccal epithelial cells, and the MMP-9 -1562C/T and IL-18 -607A/C variants were identified with PCR-RFLP.

RESULTS

Gingivitis was present in 49.3% of the adolescents examined, the rest of the group was considered healthy. The IL-18 -607C and MMP-9 -1562T alleles were found in 58.9% and 8.3% of the healthy subjects, and in 62.2% and 15.0% of the patients with gingivitis, respectively. Although differences in allele frequencies were not significant for IL-18 variant, they were significant for MMP-9 polymorphism (p=0.01, p(corr) < 0.05). Furthermore, a highly significant association of the composite genotype (formed by the variants of the both genes) with gingivitis was found (p=0.004, p(corr) < 0.05).

CONCLUSIONS

The -1562 T allele of MMP-9 gene could have a role in gingivitis in adolescents. In addition, interaction of the MMP-9 and IL-18 genes could be considered a risk factor for the development of gingivitis in children.

Metaloproteasas, remodelado vascular y syndromes aterotrombóticos

Defects in the synthesis and breakdown of the extracellular matrix (ECM) are now seen as key processes in the development of atherosclerosis and its thrombotic complications. Correlations have been observed between circulating levels of ECM biomarkers and the clinical manifestations of and risk factors for atherosclerosis. Several matrix metalloproteinases (MMPs), endopeptidases that can degrade the ECM, such as MMP-9 and MMP-10, play important roles in the pathophysiology of atherothrombosis and contribute to the expansion of abdominal aortic aneurysms. Moreover, they may also be useful biomarkers of atherosclerotic risk and serve as predictors of coronary and cerebrovascular disease recurrence. Although at present the effect of tissue inhibitors of MMPs (TIMPs) on cardiovascular disease prognosis is still uncertain, the ECM could be a promising therapeutic target in atherothrombotic disease, and several MMP inhibitors are currently undergoing clinical trials.

Functional Polymorphisms in the Matrix Metalloproteinase-9 Gene in Relation to Severity of Chronic Periodontitis

BACKGROUND

Members of the matrix metalloproteinase (MMP) family are implicated in the chronic remodeling in periodontal diseases. Therefore, we performed a case-control study to investigate a plausible association between susceptibility to chronic periodontitis (CP) and the polymorphisms in the MMP-9 (gelatinase B) gene.

METHODS

Using polymerase chain reaction with subsequent restriction analyses, MMP-9 -1562C/T and R+279Q variants were determined in 304 subjects (169 patients with CP, 76 with a mild to moderate form and 93 with severe generalized CP, and 135 age- and gender-matched unrelated control subjects).

RESULTS

The distribution of the MMP-9 -1562C/T and R+279Q genotypes and alleles did not significantly differ between cases and controls. However, the frequency of the T variant at position -1562 was marginally higher in patients with severe disease compared to those with mild to moderate forms (P <0.05; P(corr) >0.05). In further analysis, the -1562T allele was associated with a severe form of CP in men (odds ratio: 3.87; 95% confidence interval: 1.40 to 10.65; P <0.01 and P(corr) <0.05 for allele; P <0.05 and P(corr) >0.05 for genotype) but not in women.

CONCLUSION

These findings suggest that genetic polymorphisms of the MMP-9 gene are not associated with the susceptibility to CP in the Czech population; however, the promoter variant may influence the severity of the disease in men.

Circulating biomarkers of extracellular matrix remodeling and risk of atherosclerotic events

PURPOSE OF REVIEW

Disturbances of the synthesis and breakdown of the extracellular matrix of arterial walls have emerged as key features of the atherosclerotic process. Altered levels of circulating extracellular matrix markers have frequently been observed in relation to manifestations of atherosclerotic disease and its risk factors.

RECENT FINDINGS

Research has been focused on the matrix-degrading metalloproteinases, their tissue inhibitors, and procollagen peptides. The most promising matrix metalloproteinase is matrix metalloproteinase-9, which has been observed to predict rapid coronary artery narrowing, ischemic heart disease incidence, abdominal aortic aneurysm expansion, worse outcome in stroke patients, and cardiovascular death. The use of tissue inhibitors of metalloproteinases for prognostication is uncertain thus far. The procollagen marker with most prognostic potential is the marker for type III collagen turnover rate, the N-terminal propeptide PIIINP, higher levels of which predict an adverse outcome after a myocardial infarction and in chronic heart failure, and portend abdominal aortic aneurysm expansion and risk of rupture. Also, the marker for type I collagen synthesis, the C-terminal propeptide PICP, predicts adverse outcomes following myocardial infarction and in chronic heart failure. Extracellular matrix remodeling is also a promising therapeutic target, being favorably affected by several conventional cardiovascular drugs and select dietary interventions. Synthetic matrix metalloproteinase inhibitors are also under development.

SUMMARY

Circulating matrix markers have emerged as candidate biomarkers for predicting risk of subsequent atherosclerotic events. Future large longitudinal observational and intervention studies will determine the role of matrix biomarkers in diagnosis and prognostication, and as targets for intervention in cardiovascular diseases.

Effects of tibolone on the risk factors for cardiovascular diseases in postmenopausal women

Background/Aim. Tibolone is a preparation that belongs to the group of steroidal substances. The effects of the use of the use of tibolone are the consequence of the activities of its metabolities, considering that their hormonal activity depends on the type of tissue in which they develop. The aim of this study was to evaluate the influence of the use of tibolone on risk factors for the development of cardiovascular diseases in postmenopausal women. Methods. A prospective observational stady included 94 patients who had the concentration of l7? estradiol < 50 pg/ml, and who was in menopause more than a year. Out of the total number of patients, 63 accepted to receive tibolone 2.5 mg daily (tibolone group), while 31 of the patients refused to take tibolone (control group). We measured the concentration of lipids (cholesterol, LDL cholesterol, HDL cholesterol, triglicerides), antitrombin III, fibrinogen, and C-reactive protein, before and after the treatment within a 6-month period. Then, we compared the difference between the values of concentrations and tested the statistical significance of the difference. We also evaluated the changes of values in the concentrations of the examinated parameters inside a 6-month period in the control group. Results. In 31 patients of the control group, from the control group there were no significant changes in the values of the defined parameters as compared to their initial values after six months. But there were changes of statistical significance (p < 0.001) in values of the concentrations of the exeminated parameters before and after the treatment in the tibolone group. In fact, we recorded decreases in the total cholesterol by 17.8%, HDL cholesterol by 27%, LDL cholesterol by 4% (without statistical significance p > 0.05) and triglicerids by 35%. There were no statistical differences in the concentrations of antitrombin III, fibrionogen, and C-reactive proteine in the tibolone group before and after the treatment. Conclusion. The use of tibolone dose decrease the concentration of the total cholesterol, triglicerides, HDL cholesterol, without a significant decrease of LDL cholesterol. Also, the use of tibolone does not have any significant effect on the concentrations of antitrombin III, fibrinogen and C-reactive proteine. The number of serum parameters measured in this study was limited, thus that was the reason to discuss only about the metabolism of lipids in the patients from the tibolone group. The final conclusion about the risk for cardiovascular diseases in the patients on tibolone, howerer, reqnires were extensive further clinical exeminations.

Effects of Transdermal Estrogen Replacement Therapy on Cardiovascular Risk Factors

The prevalence of hypertension and cardiovascular disease increases dramatically after menopause in women, implicating estrogen as having a protective role in the cardiovascular system. However, recent large clinical trials have failed to show cardiovascular benefit, and have even demonstrated possible harmful effects, of opposed and unopposed estrogen in postmenopausal women. While these findings have led to a revision of guidelines such that they discourage the use of estrogen for primary or secondary prevention of heart disease in postmenopausal women, many investigators have attributed the negative results in clinical trials to several flaws in study design, including the older age of study participants and the initiation of estrogen late after menopause.Because almost all clinical trials use oral estrogen as the primary form of hormone supplementation, another question that has arisen is the importance of the route of estrogen administration with regards to the cardiovascular outcomes. During oral estrogen administration, the concentration of estradiol in the liver sinusoids is four to five times higher than that in the systemic circulation. This supraphysiologic concentration of estrogen in the liver can modulate the expression of many hepatic-derived proteins, which are not observed in premenopausal women. In contrast, transdermal estrogen delivers the hormone directly into the systemic circulation and, thus, avoids the first-pass hepatic effect.Although oral estrogen exerts a more favorable influence than transdermal estrogen on traditional cardiovascular risk factors such as high- and low-density lipoprotein-cholesterol levels, recent studies have indicated that oral estrogen adversely influences many emerging risk factors in ways that are not seen with transdermal estrogen. Oral estrogen significantly increases levels of acute-phase proteins such as C-reactive protein and serum amyloid A; procoagulant factors such as prothrombin fragments 1+2; and several key enzymes involved in plaque disruption, while transdermal estrogen does not have these adverse effects.Whether the advantages of transdermal estrogen with regards to these risk factors will translate into improved clinical outcomes remains to be determined. Two ongoing clinical trials, KEEPS (Kronos Early Estrogen Prevention Study) and ELITE (Early versus Late Intervention Trial with Estradiol) are likely to provide invaluable information regarding the role of oral versus transdermal estrogen in younger postmenopausal women.

Controversies about HRT--lessons from monkey models

Lessons from monkey models contribute significantly to a better understanding of the controversies in reconciling the differences in postmenopausal hormone treatment outcomes between observational and randomized trial data. Monkey studies brought attention to premenopausal estrogen deficiency with resulting premature coronary artery atherosclerosis. Recently, those monkey studies were confirmed for premenopausal women in the NHLBI-sponsored Women's Ischemia Syndrome Evaluation (WISE) Study. Monkey studies have provided convincing evidence for the primary prevention of coronary artery atherosclerosis when estrogens are administered soon after the development of estrogen deficiency. Equally convincing are the data from monkey studies indicating the total loss of these estrogens beneficial effects if treatment is delayed for a period equal to six postmenopausal years for women. An attempt has been made using the monkey model to identify the hormone treatment regimen most effective in preventing the progression of coronary artery atherosclerosis. By a substantial margin, the most effective approach is that of using estrogen containing oral contraceptive during the perimenopausal transition, followed directly by hormone replacement therapy postmenopausally. Because of similarities between human and nonhuman breast, monkeys have had a major role in clarifying controversies surrounding the breast cancer risk of estrogen only versus estrogen plus progestin therapies. The results of monkey studies suggest little or no effects of estrogen only treatment; whereas, estrogen+progestin clearly increases breast cancer risk.

Cardiovascular consequences of hormone therapy in postmenopausal women: Messages to clinicians

Results from the recent randomized clinical trials indicating that hormone therapy (HT) does not provide cardiovascular protection, but potentially harm are in profound disagreement with the sound evidence from numerous observational and experimental studies. While the observational studies have mainly assessed symptomatic recently menopausal women, the randomized trials have studied symptomless elderly postmenopausal women with established coronary heart disease or various risk factors for cardiovascular disease. Therefore, the recent trials have only revealed that HT does not provide secondary cardiovascular benefits. Since primary cardiovascular benefits of HT are rational but not yet proven in clinical trials, new studies are in demand. Until more data from recently menopausal symptomatic women are available, we need to base our decisions on existing evidence and good clinical practice. Although the potential of HT to provide cardiovascular benefits is decreased by advancing age and time since menopause, this should not preclude the use of individualized HT in younger postmenopausal women. (Reprod Med Biol 2005; 4: 1- 6).

Cardiovascular consequences of hormone therapy in postmenopausal women: Messages to clinicians

Results from the recent randomized clinical trials indicating that hormone therapy (HT) does not provide cardiovascular protection, but potentially harm are in profound disagreement with the sound evidence from numerous observational and experimental studies. While the observational studies have mainly assessed symptomatic recently menopausal women, the randomized trials have studied symptomless elderly postmenopausal women with established coronary heart disease or various risk factors for cardiovascular disease. Therefore, the recent trials have only revealed that HT does not provide secondary cardiovascular benefits. Since primary cardiovascular benefits of HT are rational but not yet proven in clinical trials, new studies are in demand. Until more data from recently menopausal symptomatic women are available, we need to base our decisions on existing evidence and good clinical practice. Although the potential of HT to provide cardiovascular benefits is decreased by advancing age and time since menopause, this should not preclude the use of individualized HT in younger postmenopausal women. (Reprod Med Biol 2005; 4: 1- 6).

Hormone therapy and cardiovascular disease--still much to be learnt

Results from the recent randomized clinical trials indicating that hormone therapy (HT) does not provide cardiovascular protection, but potential harm, are in profound disagreement with the sound evidence from numerous observational and experimental studies. While the observational studies have mainly assessed symptomatic recently menopausal women, the randomized trials have studied symptomless elderly postmenopausal women with established coronary heart disease or various risk factors for cardiovascular disease. Thus, the recent trials have revealed only that HT does not provide secondary cardiovascular benefits. Since primary cardiovascular benefits of HT are rational but not yet proven in clinical trials, new studies are in demand. Until more data from recently menopausal symptomatic women are available, we need to base our decisions on existing evidence and good clinical practice. Although the potential of HT to provide cardiovascular benefits is decreased by advancing age and time since menopause, this should not preclude the use of individualized HT in younger postmenopausal women.

Effects of Conventional or Lower Doses of Hormone Replacement Therapy in Postmenopausal Women

OBJECTIVE

The effects of hormone replacement therapy (HRT) can affect many aspects relevant to cardiovascular disease, including vasomotor function, inflammation, and hemostasis. Recent studies have demonstrated that current doses of HRT exert a mixture of both protective and adverse effects. In the current study, we compared the effects of lower doses of HRT (L-HRT) and conventional doses of HRT (C-HRT) on a variety of relevant cardiovascular parameters.

METHODS AND RESULTS

This randomized, double-blind, crossover study included 57 women who received micronized progesterone 100 mg with either conjugated equine estrogen 0.625 mg (C-HRT) or 0.3 mg (L-HRT) daily for 2 months. L-HRT showed comparable effects to C-HRT on high-density lipoprotein cholesterol and triglyceride levels, but not on low-density lipoprotein cholesterol levels. C-HRT and L-HRT significantly improved the percent flow-mediated dilator response to hyperemia from baseline values (both P<0.001) by a similar degree (P=0.719). C-HRT significantly increased high-sensitivity C-reactive protein (hsCRP) levels from baseline values (P<0.001); however, L-HRT did not significantly change hsCRP (P=0.874). C-HRT and L-HRT significantly decreased antithrombin III from baseline values (P<0.001 and P=0.042, respectively). C-HRT significantly increased prothrombin fragment 1+2 (F1+2) from baseline values (P<0.001); however, L-HRT did not significantly change F1+2 (P=0.558). Of interest, the effects of C-HRT and L-HRT on hsCRP, antithrombin III, and F1+2 were significantly different (all P<0.001). C-HRT and L-HRT significantly reduced plasma PAI-1 antigen levels from baseline values (P=0.002 and P=0.038, respectively) to a similar degree (P=0.184).

CONCLUSIONS

Compared with C-HRT, L-HRT has comparable effects on lipoproteins, flow-mediated dilation, and PAI-1 antigen levels. However, L-HRT did not increase hsCRP or F1+2 levels, and it decreased antithrombin III less than C-HRT.

Should Progestins Be Blamed for the Failure of Hormone Replacement Therapy to Reduce Cardiovascular Events in Randomized Controlled Trials?

Many observational studies and experimental and animal studies have demonstrated that estrogen replacement therapy (ERT) or hormone replacement therapy (HRT) (estrogen plus progestin) significantly reduces the risk of coronary heart disease. Nonetheless, recent randomized controlled trials demonstrated some trends toward an increased risk of cardiovascular events rather than a reduction of risk. Recently, both the HRT and ERT arms of the Women’s Health Initiative (WHI) study were terminated early because of an increased/no incidence of invasive breast cancer, increased incidence of stroke, and increased trend/no protective effects of cardiovascular disease. We discuss the controversial effects of HRT and ERT on cardiovascular system and provide a hypothesis that the failure of HRT and ERT in reducing the risk of cardiovascular events in postmenopausal women might be because of the stage of their atherosclerosis at the time of initiation of HRT or ERT.

Relations of Plasma Matrix Metalloproteinase-9 to Clinical Cardiovascular Risk Factors and Echocardiographic Left Ventricular Measures

Background— Plasma levels of matrix metalloproteinase-9 (MMP-9), a key determinant of extracellular matrix degradation, are increased in heart failure and in acute coronary syndromes. We investigated cross-sectional relations of plasma MMP-9 to vascular risk factors and echocardiographic left ventricular (LV) measurements.

Methods and Results— We studied 699 Framingham Study participants (mean age, 57 years; 58% women), free of heart failure and previous myocardial infarction, who underwent routine echocardiography. We examined sex-specific distributions of LV internal dimensions (LVEDD) and wall thickness (LVWT) and sampled persons with both LVEDD and LVWT below the sex-specific median (referent, n=299), with increased LVEDD (LVEDD ≥90th percentile, n=204) and increased LVWT (LVWT ≥90th percentile, n=221) in a 3:2:2 ratio. Plasma MMP-9 was detectable in 138 persons (20%). In multivariable models, increasing heart rate (OR per SD, 1.41; 95% CI, 1.17 to 1.71) and antihypertensive treatment (OR, 1.63; 95% CI, 1.06 to 2.50) were key clinical correlates of detectable plasma MMP-9. In multivariable-adjusted models, detectable plasma MMP-9 was associated with increased LVEDD (OR, 2.84; 95% CI, 1.13 to 7.11), increased LVWT (OR, 2.54; 95% CI, 1.00 to 6.46), and higher LV mass ( P =0.06) in men but not in women (OR for increased LVEDD, 1.37; 95% CI, 0.54 to 3.46; for increased LVWT, 0.99; 95% CI, 0.39 to 2.52; P =0.59 for LV mass).

Conclusions— In our community-based sample, detectable plasma MMP-9 levels were associated with increased LV diastolic dimensions and increased wall thickness in men. These observations indicate that plasma MMP-9 level may be a marker for cardiac extracellular matrix degradation, a process involved in LV remodeling.

Postmenopausal hormone therapy before and after the women's health initiative study: what consequences?

This review focuses on the question of whether the Women's Health Initiative (WHI) was a test of primary versus secondary cardiovascular benefits of postmenopausal hormone therapy. Evidence is presented to support the conclusion that the WHI was a secondary intervention trial and that primary cardiovascular benefits of hormone therapy are rational, likely, but not yet proven. The review makes clear that hormone therapy is not a 'cardiovascular drug' for the treatment of coronary heart disease; but rather that the public health debate is whether hormone therapy, used for the treatment of menopausal symptoms, provides any cardiovascular benefits that might offset its risk.

Hormone Replacement Therapy and Cardiovascular Disease: Lessons from a Monkey Model of Postmenopausal Women

Concerns exist about the cardiovascular effects of hormone replacement therapy (HRT) in postmenopausal women because results from the Women's Health Initiative (WHI) and the Heart and Estrogen/Progestin Replacement Study (HERS) are contradictory. In both of these studies, postmenopausal conjugated equine estrogens + medroxyprogesterone acetate did not reduce risk, and somewhat increased the risk of myocardial infarction in both primary (WHI) and secondary (HERS) prevention. These results appear to contradict numerous observational clinical trials and animal studies, which reported profound beneficial effects of HRT on cardiovascular disease risk. Results of both human and monkey studies indicate that estrogen replacement therapy (ERT)/HRT is effective in inhibiting progression of early stage (fatty streak) atherosclerosis but that ERT/HRT is much less effective in inhibiting progression of more advanced (established plaque) atherosclerosis. Results of these monkey studies are consistent with those of studies in women wherein ERT/HRT was initiated in postmenopausal women with different initial amounts of atherosclerosis. Based on these findings, it is speculated that ERT/HRT may be more cardioprotective in younger postmenopausal women with less coronary artery disease, and less effective in women with established coronary artery disease. Researchers are challenged to define the relative cardiovascular risk/benefit in different populations of postmenopausal women based on differences in age, amounts of pre-existing atherosclerosis, and risk factors.

Hormone replacement therapy is associated with less coronary atherosclerosis in postmenopausal women

Most observational studies indicate that hormone replacement therapy (HRT) protects women from cardiovascular disease. Two recent randomized trials, however, showed no reduction in coronary events with HRT in postmenopausal women. A randomized study evaluating subclinical atherosclerosis showed a beneficial effect of estrogen. In the current study we evaluated the association between HRT and coronary artery atherosclerosis, as quantified by coronary artery calcium score. Current users of HRT were significantly more likely to have a coronary artery calcium score less than 100 and were less likely to have a score greater than 400 than non-HRT users. After adjustment for cardiac risk factors, current use of HRT was associated with a significant reduction of coronary artery calcium score (-28; 95% confidence interval, -48 to -10). The average age of users was 59 yr, the mean duration of use was 9 yr, and the duration of HRT use was significantly associated with a reduction in coronary artery calcium. These results suggest that HRT suppresses atherosclerosis in the coronary arteries. The failure to modify the cardiovascular event rate in clinical trials could result from the adverse effect of HRT on complicated lesions. Additional mechanistic studies may help identify therapeutic strategies that could maximize a potential benefit of HRT on early atherogenesis while minimizing adverse proinflammatory and procoagulant effects on complicated plaque lesions.

MPA and postmenopausal coronary artery atherosclerosis revisited

Whether progestins, particularly medroxyprogesterone acetate (MPA), attenuate the cardiovascular benefits of postmenopausal estrogen replacement therapy (ERT) has been controversial for over a decade. Concerns related first to findings that MPA attenuated increases of high density lipoprotein cholesterol (HDLC) concentrations of postmenopausal women compared to conjugated equine estrogen (CEE) alone. That observation was followed by early cynomolgus monkey studies that suggested MPA decreased estrogen's cardiovascular benefits (vascular reactivity and coronary artery atherosclerosis inhibition). In a more recent and larger trial with cynomolgus monkeys, no differences were seen in the coronary artery atherosclerosis protective effect of CEE when MPA was co-administered (HRT). The lack of attenuation of ERTs benefits by progestins has also been seen in at least three studies of carotid artery intima-media thickness (IMT) of postmenopausal women. Additionally, the majority of studies of vascular reactivity of postmenopausal women have not found differences when CEE is given alone or with MPA. Seven observational studies of cardiovascular outcomes of postmenopausal women permit separate consideration of ERT versus HRT use; there is no evidence of attenuation of ERTs benefits by progestin use. In conclusion, it is evident that the current experimental, clinical, and observational data do not provide evidence that progestins attenuate estrogen's cardiovascular benefits.

Significant differential effects of hormone therapy or tibolone on markers of cardiovascular disease in postmenopausal women: a randomized, double-blind, placebo-controlled, crossover study

OBJECTIVE

The objective was to compare the effects of tibolone and hormone therapy (HT) on lipid profile, vasodilation, and factors associated with inflammation and hemostasis.

METHODS AND RESULTS

Fifty-three women received micronized progesterone (MP, 100 mg) with conjugated equine estrogen (CEE, 0.625 mg) or tibolone (2.5 mg) daily for 2 months, with a 2-month washout period. Compared with HT, tibolone significantly reduced total cholesterol (P<0.001), triglyceride (P<0.001), and HDL cholesterol (P<0.001) levels as well as triglyceride/HDL cholesterol ratios (P<0.001) but not LDL cholesterol levels. Tibolone significantly improved flow-mediated brachial artery dilator response to hyperemia from baseline values (P<0.001) by a magnitude similar to that found with HT (P=0.628). Compared with tibolone, which showed no changes, HT significantly increased high-sensitivity C-reactive protein (hsCRP, P=0.030) and reduced antithrombin III (P<0.001). HT and tibolone significantly increased prothrombin fragment 1+2 (F1+2) from baseline values (P<0.001 and P=0.004, respectively). The effects of HT and tibolone on hsCRP, antithrombin III, and F1+2 were significantly different. HT and tibolone significantly reduced plasma levels of plasminogen activator inhibitor type 1 antigen from baseline levels (P=0.006 and P=0.005, respectively) to a similar degree (P=0.988).

CONCLUSIONS

Tibolone significantly improved flow-mediated brachial artery dilator response by a magnitude similar to that found with CEE+MP; however, tibolone did not significantly change hsCRP and antithrombin III, and tibolone increased F1+2 less than did CEE+MP.

Hormone replacement therapy and inflammation: interactions in cardiovascular disease

Inflammation plays a central role in the pathogenesis of many forms of vascular disease, including atherosclerosis. Atherogenesis begins with endothelial damage, and the damaged endothelium expresses adhesion molecules, chemokines, and proinflammatory cytokines that direct atherosclerotic plaque formation and spill into the circulation as biomarkers of atherosclerotic disease risk. Menopausal hormone therapy, including a variety of estrogen preparations with or without a progestin, has negative modulatory effects on most of these soluble inflammatory markers, including E-selectin, vascular cell adhesion molecule-1, intercellular adhesion molecule-1, monocyte chemoattractant protein-1, and tumor necrosis factor-alpha, inconsistent effects on interleukin-6, and stimulatory effects on transforming growth factor-beta, a vasoprotective cytokine. In contrast, C-reactive protein, a circulating proinflammatory cytokine produced in both liver and atherosclerotic arteries, increases in response to oral conjugated estrogens but not to transdermal estrogen. Although C-reactive protein is clearly linked to increased cardiovascular disease risk in women, the hormone-induced rise in this biomarker is not associated with increased risk and may be related to a first-pass effect of C-reactive protein production in the liver after oral estrogen absorption. Many important questions about the effects of ovarian hormones on vascular inflammation and the pathogenesis of vascular disease cannot be answered in human subjects. Insights from fundamental mechanistic studies in animal models are needed to delineate the cellular/molecular events that determine whether these hormones protect or injure blood vessels.

Can a healthy endothelium influence the cardiovascular effects of hormone replacement therapy?

Emerging clinical and observational evidences suggest that estrogen confers physiologic benefits that are receptor mediated and depend on the integrity and functional status of the endothelium within the coronary vasculature. In postmenopausal women, estrogen replacement therapy (ERT) and hormone replacement therapy (HRT) regimens can enhance the lipoprotein panel; blunt the expression of numerous cytokines, chemokines, and other proinflammatory mediators of endothelial injury and vascular smooth muscle cell proliferation; up-regulate endothelial nitric oxide synthase activity and nitric oxide production; and augment fibrinolysis potential and vasodilator capacity (diminish arterial resistance). Advancing age and atherosclerotic injury to the vessel wall tend to deplete estrogen receptors, compromise endothelial function, promote thrombus formation, and thus potentially diminish the efficacy of ERT and HRT. Therefore, optimizing the clinical benefits of these regimens in postmenopausal women depends largely on promoting a healthy endothelium through life-style modifications that diminish coronary risk.

Effects of continuous combined hormone replacement therapy on inflammation in hypertensive and/or overweight postmenopausal women

OBJECTIVE

We observed that estrogen did not show cardioprotective benefits in type 2 diabetic postmenopausal women. We hypothesized that hypertensive and/or overweight women may be less likely to realize cardiovascular benefits from estrogen.

METHODS AND RESULTS

We administered micronized progesterone (MP) 100 mg or medroxyprogesterone acetate (MPA) 2.5 mg with conjugated equine estrogen (CEE) 0.625 mg daily during 2 months to 35 hypertensive and/or overweight postmenopausal women with a randomized, double-blind, crossover design. With significant changes of lipoproteins, CEE+MP or MPA significantly improved flow-mediated dilation and reduced plasma E-selectin, intercellular adhesion molecule type-1, monocyte chemoattractant protein-1, and tumor necrosis factor-alpha levels (P<0.001, P<0.001, P=0.021, P<0.001, and P<0.001 by ANOVA, respectively), but not C-reactive protein and fibrinogen levels. Of note, there were no significant differences between each therapy regarding these effects. However, the magnitude of improvement of flow-mediated dilation in these women was less than in healthy postmenopausal women and more than in diabetic postmenopausal women reported by our previous studies. The effects of CEE+MP or MPA on inflammatory markers were comparable to healthy postmenopausal women, but not comparable to diabetic postmenopausal women.

CONCLUSIONS

Estrogen combined with synthetic progestin significantly improved flow-mediated brachial artery dilator response and reduced inflammation markers in hypertensive and/or overweight women, comparable to estrogen combined with natural progesterone.

Effects of hormone replacement therapy on coagulation and fibrinolysis in postmenopausal women

It has been speculated that hormone replacement therapy (HRT) containing relatively low dose of estrogen would be different from oral contraceptive pills in causing thromboembolism because activation of coagulation depends on the amount of estrogen. In contrast to this knowledge, activation of coagulation pathways has been detected in postmenopausal women treated with HRT in the observational and clinical studies. In this regard, recent studies have reported a 2 to approximately 4 fold risk of venous thromboembolism or pulmonary embolism in postmenopausal women receiving HRT than in non-users of estrogen. On the other hands, HRT has shown to enhance systemic fibrinolysis with decreased plasma plasminogen activator inhibitor-1 (PAI-1) levels. In addition, levels of D-dimer exhibited a significant inverse correlation with PAI-1 levels, suggesting enhanced fibrinolysis potential. However, small doses of estrogen/progestogen induce increases in fibrinolytic capacity via a marked reduction of PAI-1. In other words, HRT at conventional dosages may affect fibrinolytic activity to a greater extent than coagulation activity, whereas the converse trend holds at higher estrogen doses. The increase in fibrinolytic potential was independent of any effect on coagulation of CEE at conventional dosages. However, in contrast to healthy postmenopausal women, we recently reported that HRT did not significantly decrease PAI-1 antigen levels and rather, increased tissue factor activity and prothrombin fragment F(1+2) levels from baseline in hypertensive and/or overweight postmenopausal women. Activation of coagulation following HRT may not be balanced by activation of fibrinolysis in some postmenopausal women. Thrombogenic events are considered more likely in patients with certain heritable conditions, such as platelet antigen-2 (PIA-2) polymorphisms. Further, Factor V Leiden mutation increases the risk of primary and recurrent venous thromboembolic events by three to sixfold and the risk of myocardial infarction. Indeed, HRT may decrease or increase atherothrombosis risk depending on the presence of Factor V Leiden mutation. Thus, HRT should not be initiated in women with established coronary artery disease or the coexistence of other risk factors for hypercoagulability-malignancy, immobility, obesity, diabetes, advanced age, or inherited traits. However, HRT at conventional dosages improves fibrinolysis potential in healthy postmenopausal women.