Skip Navigation

Cardiovascular Research 2002 53(3):642-649; doi:10.1016/S0008-6363(01)00461-8
© 2002 by European Society of Cardiology
This Article
Right arrow Abstract Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by Störk, S.
Right arrow Articles by Angerer, P.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Störk, S.
Right arrow Articles by Angerer, P.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

Copyright © 2002, European Society of Cardiology

The effect of 17β-estradiol on MCP-1 serum levels in postmenopausal women

Stefan Störk*, Klaus Baumann, Clemens von Schacky and Peter Angerer

Medizinische Klinik, Klinikum der Universität München - Innenstadt, Ziemssenstr. 1, D-80336 München, Germany

* Corresponding author. Tel.: +49-931-201-7088, fax: +49-931-201-7124 s.stoerk{at}medizin.uni-wuerzburg.de

Received 4 July 2001; accepted 17 September 2001


   Abstract
Top
 Abstract
1. Introduction
 2. Methods
 3. Results
 4. Discussion
 References
 
Objective: Monocyte chemoattractant protein-1 (MCP-1) is considered a propagator of atherosclerosis and a key modulator of monocyte activity. Hormone replacement therapy (HRT) is currently being investigated as a means towards prevention of atherosclerosis. We aimed to assess (1) the range of circulating MCP-1 levels in postmenopausal women, (2) the correlation between MCP-1 and atherosclerotic burden, and (3) the effects of commencement and discontinuation of HRT on MCP-1 serum levels. Methods: This clinical prospective trial investigated 51 postmenopausal women at increased risk for cardiovascular events who were randomized to receive either no HRT or 1 mg 17β-estradiol continuously plus sequential progestagen over 1 year. Intima-media thickness (IMT) of carotid and femoral arteries was measured by ultrasound. Serum levels of MCP-1 and cellular adhesion molecules were measured by ELISA. Results: At baseline, MCP-1 levels and overall mean maximum IMT correlated (r=0.589; P<0.0001, Pearson's coefficient). MCP-1 levels in serum gradually decreased after 3, 6, and 12 months of HRT by 16.8±15.7% at 12 months (P<0.0001, MANOVA). Similarly, all cellular adhesion molecules decreased significantly by 6–12%. After 12 months, women decided whether to continue or discontinue treatment. At 18 months, in women discontinuing HRT (n=17), MCP-1 levels rose by 21±20% (P=0.003), but remained lowered in women continuing HRT. Conclusion: Our observations indicate that 17β-estradiol may have an antiatherosclerotic effect by reducing MCP-1 serum levels and cell adhesion molecules.

KEYWORDS Arteries; Atherosclerosis; Cytokines; Hormones; Infection/inflammation


   1. Introduction
Top
 Abstract
 1. Introduction
2. Methods
 3. Results
 4. Discussion
 References
 
Inflammation is currently considered a key concept in atherogenesis [1,2]. Among several factors with chemotactic activity for monocytes, monocyte chemoattractant protein-1 (MCP-1) may be an especially important mediator of atherogenic signals [3]. Even under atherogenic conditions, MCP-1 deficient knock-out mice did not develop atherosclerosis [4,5]. Recent studies detected increased MCP-1 mRNA levels in both animal [6,7] and human [6,8] atherosclerotic arteries. Estradiol inhibited the mRNA expression of the murine MCP-1 homologue, JE, in activated macrophages [9] and fibroblasts [10]. In rabbits, both ovariectomy and hypercholesterolemia induced an increase in MCP-1 mRNA expression and protein levels in the thoracic aorta tissue that could be prevented by physiological concentrations of 17β-estradiol [11]. These observations supported the hypothesis that the presumed antiatherogenic effects of estradiol may be mediated by prevention of macrophage accumulation in the atherosclerotic area [10].

Recruitment of circulating leukocytes at sites of atherosclerosis is mediated through a family of adhesion molecules, among them intercellular cell adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and endothelial–leukocyte adhesion molecule-1 (E-selectin). Serum levels of these molecules are elevated in subjects with coronary and carotid artery disease [12] and are decreased after estrogen therapy [13–15].

Intima-media thickness (IMT) of peripheral arteries, measured by ultrasound, correlates well with the extent and severity of atherosclerosis in coronary arteries [16,17] and predicts future myocardial infarction and stroke [18–22]. Change of IMT in peripheral arteries is an established intermediate end point in intervention trials on prevention of atherosclerosis [23].

There is only scarce data on circulating MCP-1 protein levels in humans and their relation to atherosclerotic disease. It is also unknown whether MCP-1 levels are modulated by sex hormones in humans. Therefore, we aimed (1) to define the range of circulating serum MCP-1 levels in untreated postmenopausal women, (2) to explore any relationship between MCP-1 and atherosclerotic burden as estimated by IMT measurement, and (3) to prospectively investigate the effects of commencement and discontinuation of sequential HRT with 17β-estradiol on serum MCP-1 levels.


   2. Methods
Top
 Abstract
 1. Introduction
 2. Methods
3. Results
 4. Discussion
 References
 
2.1. Study population and data collection
We report data on 51 healthy postmenopausal women who took part in a larger randomized prospective trial that investigated the effect of sequential low-dose HRT on atherosclerosis progression in postmenopausal women [24]. The design and main results of this trial have been reported [24]. In short, study subjects were eligible if they exhibited at least one site of >1.0 mm intima-media thickness at the carotid artery system and if they did not suffer from severe renal, liver, or thyroid metabolism disorders or any malignancy. Postmenopausal status was defined as amenorrhea for more than 12 months or bilateral ovariectomy or FSH levels >40 mIU/ml with hysterectomy. Participants were randomized to receive either no HRT (control group) or one of two sequential HRT regimens containing 1 mg 17β-estradiol per day continuously, plus 25 µg gestodene for the last 12 days of either each month or every third month. After 12 months, women were free to decide whether to continue or discontinue treatment. Inclusion criteria for the substudy on MCP-1 were: willingness to participate in the 18-month study, off HRT for at least 1 year prior to study entry, a complete set of 5 blood specimens over 18 months, and compliance of >90% as assessed by pill count over the first year. Women reported upon here were not significantly different from the women fulfilling the same criteria but without a complete series of five blood samples (data not shown). Subjects with signs of apparent infection or subjects on cholesterol-lowering therapy were not eligible. Hyperlipidemia was diagnosed if the subject had levels of total cholesterol higher than 260 mg/dl (6.734 mmol/l). Collection of serum samples for MCP-1 measurements and routine laboratory workup was performed at baseline, and after 3, 6, 12, and 18 months. Because the effect of HRT on ICAM-1, VCAM-1, and E-selectin has been assessed in earlier studies [13–15], these molecules were measured only at baseline and after 12 months of therapy. Serum samples were taken non-fasting, processed immediately, and stored at –80°C until analysis. All analyses were performed in duplicates by analytical personnel, blinded to all aspects like treatment allocation. Medical and medication history was obtained by standardized interview. All participants gave their written informed consent. The study was approved by the local ethics committee of the faculty of medicine of the University of Munich. It was conducted according to the International Conference for Harmonisation–Guidelines for Good Clinical Practice (ICH–GCP).

2.2. Ultrasound measurements
Atherosclerotic burden was measured as IMT of the carotid and femoral artery in 10 sites per subject by high-resolution ultrasound (7.5 MHz transducer, Apogee CX Color, ATL), as described in detail [24]. Five predefined segments were visualized on both sides: the distal 10 mm of the common carotid artery, the carotid bifurcation from the widening of the artery up to the flow divider, the proximal 10 mm of the internal carotid artery, the distal 10 mm of the common femoral, and the proximal 10 mm of the superficial femoral artery. Only measurements of the wall far from the probe were considered for the calculation of correlation because ultrasound measurements of the near wall tend to underestimate the true histological thickness [25]. IMT was measured from the digitized image twice and averaged at the site of its maximum extent within each segment by means of the software NIH-Image (National Institutes of Health) on a Power Macintosh 8100/80 with a high-resolution screen. The mean of maximum far wall IMT values for all carotid segments, for all femoral segments, and for all 10 segments calculated and are referred to as carotid, femoral, and overall mean maximum IMT per subject, respectively. The latter was defined as a surrogate marker reflecting atherosclerotic burden.

2.3. Analytical methods
Human monocyte chemoattractant protein-1 assay: MCP-1 in serum was quantified by a sandwich enzyme immunoassay technique (human MCP-1, QuantikineTM, R&D Systems, Germany) according to the manufacturer's protocol. The storage time of aliquots before analysis was up to 24 months without intermittent thawing. After completion of the study, each participant's sequential samples were run concurrently. The recovery rate for serum averaged at 103%, the sensitivity was 5.0 pg/ml, the intra- and interassay variability was reported to be 4.8 and 5.8%, respectively. In order to detect any systematic drift of MCP-1 protein levels during storage time, a subset of 35 pairs was measured twice, at the time of blood collection and after 24 months. ICAM-1, VCAM-1, and E-selectin were assayed by enzyme-linked immunosorbent assay kits, according to the manufacturer's protocol (R&D Systems). The coefficients of variation for these assays were below 8.5%.

Clinical routine laboratory measurements: All other reported parameters were assessed as part of the clinical routine in our clinical laboratory.

2.4. Statistical analysis
For data analysis the SPSS 6.1.1 software package (SPSS, Chicago, IL, USA) was used. Gaussian distribution was tested by the Kolmogorov–Smirnov–Lilliefors test. Comparison between groups was performed by the Student's t-test, Mann–Whitney U-test, and {chi}2-test according to the nature of the data. In the cross-sectional analysis, the association between MCP-1 and IMT was assessed by Pearson's correlation coefficient. This relationship was re-assessed in a multivariate regression analysis after controlling for potential confounders. Longitudinal measurements were compared by multivariate analysis of variance (MANOVA) with percentage change of MCP-1 levels from baseline to timepoint after study entry as dependent variable, treatment group and control group as factor, and baseline value as covariate. All values represent mean±S.D. unless otherwise stated. A 2-sided P-value of 0.05 was considered statistically significant.


   3. Results
Top
 Abstract
 1. Introduction
 2. Methods
 3. Results
4. Discussion
 References
 
All biochemical parameters were normally distributed. At baseline, groups did not differ significantly with the exception of aspirin use which was more frequent in the HRT group and creatinine values which were slightly lower in the control group, probably accounted for by chance (Tables 1 and 2Go). Baseline values for MCP-1 ranged from 208 to 643 pg/ml (380±107 pg/ml; Table 2A). Reflecting increased cardiovascular risk, carotid mean maximum IMT was 1.07±0.27 mm (Table 1) [21]. No differences were observed in ultrasound parameters between groups at baseline (Table 1). None of the participants had a history or clinical symptoms of peripheral artery disease or myocardial infarction.


View this table:
[in this window]
[in a new window]

  		Table 1 Characteristics of participants and use of relevant drugs at baseline and after 12 months according to treatment group

 

View this table:
[in this window]
[in a new window]

  		Table 2
 
Between overall mean maximum IMT and MCP-1 at baseline a correlation of r=0.589 was observed (P<0.0001, Pearson's coefficient; Fig. 1 and Table 3) and weaker associations were found for LDL-cholesterol (r=0.33), cigarette consumption (r=0.32), years since menopause (r=0.28). Adjustment for age, body mass index, smoking, blood pressure, amenorrhoic interval, fibrinogen, cholesterol, creatinine, and use of aspirin in a linear regression analysis model did not alter the level of significance. No correlation was found between mean maximum IMT and levels of ICAM-1, VCAM-1 and E-selectin.


Figure 1
View larger version (24K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Fig. 1 The correlation between MCP-1 levels and mean maximum intima-media thickness (IMT) of 10 segments in carotid and femoral arteries at baseline (n=51; r=0.589, P=0.00004; Pearson's coefficient).

 

View this table:
[in this window]
[in a new window]

  		Table 3 Correlation between serum MCP-1 and intima-media thickness of carotid and femoral arteries (overall mean maximum IMT)

 
In order to examine stability of MCP-1 protein during storage time a subset of 35 pairs was analyzed twice, at time of blood collection and after 24 months. The correlation coefficient for the two timepoints was 0.962 (r2=0.926, CI 95%: 0.912, 0.984; P<0.0001) with a slope of y=2.96+1.021x, indicating excellent sample stability.

After commencement of HRT, MCP-1 levels decreased by 10% after 3 months, by 14% after 6 months, and by 17% after 12 months (P<0.0001 compared to initial values, MANOVA) to a mean level of 316±90 pg/ml (P=0.036 compared to controls, t-test; Fig. 2 and Table 2A). In the control group, the variation of MCP-1 levels over time was 7.6% (Fig. 2). Similarly, levels of ICAM-1, VCAM-1 and E-selectin had decreased significantly by 7.6, 6.0, and 11.9%, respectively, at 12 months on HRT and remained unchanged in controls (Table 2B). Commencement of HRT lowered FSH by 50% but remained unaltered in the control group. Antihypertensive therapy was initiated in few patients and in similar proportions in both groups (Table 1). Lipid lowering drugs were not commenced in either group during the observation period. None of the subjects took any vitamin supplements.


Figure 2
View larger version (33K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Fig. 2 The effect of commencement and withdrawal of HRT on percentage change of MCP-1 levels from baseline. Data are mean±S.E.M. MANOVA for differences within groups for % change. *P<0.01, **P<0.001, ***P<0.0001 for comparison from baseline to timepoint, and {dagger}P<0.001, {ddagger}P<0.001 for comparison between months 12 and 18.

 
After 12 months, women decided whether to continue or discontinue HRT. There was no difference in subject characteristics in the groups which continued or discontinued HRT after 12 months (data not shown). In women who continued HRT (n=15), levels of MCP-1 levels remained lowered, whereas in women who stopped HRT (n=17), levels of MCP-1 increased by 22.5% at 18 months (P=0.004). In the control group, in women who continued without HRT, levels of MCP-1 (n=12) remained high. In women of the control group who started HRT (n=7), levels of MCP-1 decreased by 27% at 18 months (P=0.0003; Fig. 2 and Table 2). None of the other serum parameters that were determined paralleled the changes in MCP-1 levels.

In order to explore whether diabetes mellitus and hypertension affected the observed changes in MCP-1 levels differently in the two groups, we repeated the analysis after exclusion of hypertensive and diabetic subjects. In a separate analysis we excluded only subjects on aspirin. In both analyses the changes of MCP-1, ICAM-1, VCAM-1, and E-selectin were in the same direction and in the same order of magnitude as observed in the entire cohort.

Because in the main study a significant effect of HRT on fibrinogen, LDL-cholesterol, and a trend for lower blood pressure levels has been observed [24], the change of each of these variables was controlled separately in a multivariate regression analysis in order to identify them as potential intermediate steps. If controlled, neither the change in fibrinogen, nor LDL-cholesterol, nor blood pressure levels weakened the effect of HRT on MCP-1 in this regression analysis.

After 12 months of treatment, correlation between MCP-1 and IMT disappeared if the whole cohort was considered (r=0.233, n.s.). This was due to changes of MCP-1 levels in the HRT group whereas the association remained close in the control group (r=0.727; P=0.0002; Table 3).


   4. Discussion
Top
 Abstract
 1. Introduction
 2. Methods
 3. Results
 4. Discussion
References
 
The present investigation demonstrated a clear dependence of serum MCP-1 levels on HRT with 17β-estradiol in a cohort of postmenopausal women with increased risk for future cardiovascular events evidenced by increased IMT and a high prevalence of cardiac risk factors. At baseline, in women not using HRT, a close correlation was found between MCP-1 levels and mean maximum IMT of carotid and femoral arteries combined. After 12 months of HRT, MCP-1 levels were reduced by 17%, followed by a 22.5% increase 6 months after discontinuation.

To our knowledge, this is the first report on the effects of 17β-estradiol on human MCP-1 levels in a prospective setting. Reduction in MCP-1 by 17β-estradiol has been consistently observed in in vitro [9] and animal studies [11]. In rabbits fed a cholesterol-enriched diet, 17β-estradiol at physiological levels dose-dependently reduced both MCP-1 gene and protein expression to values observed in ovary-intact rabbits. The authors concluded that estradiol most likely exerted its regulatory effect on MCP-1 at the level of transcription [11]. However, a direct inhibitory action of estradiol on MCP-1 production in macrophages has also been demonstrated [9,10,26]. The mechanisms by which 17β-estradiol influences MCP-1 are not completely understood, but two pathways are favoured. Firstly, experimental and animal data suggest a link between increased production of nitric oxide and decreased MCP-1 expression after exposure to estradiol [9,10,27–30]. Secondly, circulating estradiol is thought to decrease levels of cytokines in vivo by downregulation of tumor necrosis factor-{alpha} [31,32] that in turn leads to decreased levels of MCP-1 as evidenced in experiments with peripheral blood mononuclear cells from postmenopausal women at physiological concentrations of estradiol [33].

Our data show a cause and effect relationship between change of MCP-1 levels and start or stop of HRT in humans. This effect was observed regardless of other accompanying risk factors as cholesterol levels and smoking. In a smaller study, estrogen supplement therapy reduced the MCP-1 receptor (CCR2) expression in hypercholesterolemic postmenopausal women [34]. This lends support to the concept of a ‘closeD' ligand/receptor loop [35,36], i.e. direct interaction between a protein product and its receptor. In future studies we intend to elucidate the effect of HRT on this presumed ligand/receptor loop. Increased levels of MCP-1 might arise from atheromata themselves, reflecting their quantity (atherosclerotic burden) or quality (the degree of inflammatory activity within these lesions) [2]. Whether atherogenesis, enhanced after menopause, elevates MCP-1 levels or whether elevated MCP-1 causes atherogenesis can not be decided from our data. Nevertheless our findings support the view that both processes, atherosclerosis and inflammation as expressed by MCP-1, are firmly associated.

Other interventions have been demonstrated to influence levels of MCP-1: in a randomized trial in patients after acute myocardial infarction, angiotensin-converting enzyme (ACE) inhibition reduced MCP-1 protein levels after 4 weeks of treatment [37]. Data from our laboratory demonstrated that in unstimulated and adherence-activated mononuclear cells of healthy men, MCP-1 gene expression was reduced by about 40 and 30%, respectively, after ingestion of dietary {omega}-3 fatty acids [38]. This effect was thought to contribute to the mitigation by {omega}-3 fatty acids on the course of human coronary atherosclerosis, as assessed by angiography [39]. The effect of lipid lowering therapies on human MCP-1 has still to be shown but experimental and animal data reported inhibition of MCP-1 synthesis by statins [40] and probucol [41]. Several situations in clinical and preclinical cardiovascular disease have been associated with increased levels of MCP-1. Cross-sectional data from a Japanese cohort suggest that circulating MCP-1 levels increase with age [42]. We adjusted our data for age, and results remained unchanged. Hypertension by itself may increase circulating MCP-1 levels. In aortas of rats with angiotensin II induced hypertension MCP-1 mRNA was increased, and this effect was reversed after treatment with the nonspecific vasodilator hydralazine [43]. In our study at baseline, a higher number of subjects of the HRT group was on antihypertensive therapy and exhibited higher systolic blood pressure levels at rest although these differences did not reach statistical significance. Nevertheless, baseline MCP-1 levels were not different between groups. The type of antihypertensive medication at baseline was only slightly different with angiotensin-converting enzyme inhibitors and calcium antagonists used more frequently in the HRT group. Throughout the study a similar proportion of subjects in both groups was started on antihypertensive medication. It therefore seems unlikely that these subtle differences accounted for the pronounced effect on MCP-1. Our exploratory multivariate linear regression analysis also indicated that the observed effect of HRT on MCP-1 was neither mediated by changes in blood pressure, nor LDL cholesterol, nor fibrinogen.

Recently, a lower risk for hemodynamically relevant peripheral arterial disease in previous long term users of HRT was described [44,45]. Involvement of proximal (e.g. femoral) arteries was associated with a higher mortality than involvement of distal (e.g. tibial) arteries [46]. We therefore combined the IMT for the carotid artery, an elastic vessel, and the femoral artery, a muscular vessel, as a reflection of individual atherosclerotic burden. In the present study, in an exploratory analysis at baseline, a strong correlation between MCP-1 and the overall mean maximum IMT, reflecting atherosclerotic burden, was observed. At baseline, none of the women was on HRT. After 12 months of therapy, this association disappeared due to the change of MCP-1 levels in the HRT group, as shown by the preserved correlation in the control group. This latter finding corroborates the validity of the correlation between MCP-1 and IMT at baseline.

Levels of adhesion molecules ICAM-1, VCAM-1, and E-selectin, decreased in the same order of magnitude as reported from studies using higher dosages of estrogen [13–15]. This suggests a potential for antiinflammatory effects at this comparatively low estrogen dose although lipid levels were unaltered. The modulation of endothelial–leukocyte adhesion molecule expression by estrogen is a particularly important feature, since the derangement of this process has been shown to be one of the earliest steps of atherogenesis [47,48]. Of note, the HRT used in this study was able to suppress all markers of endothelial–leukocyte interaction. However, only for MCP-1 the correlation with IMT was found. This might indicate that MCP-1 is not only involved in early atherogenesis but also a persisting propagator of atherosclerosis.

In clinical terms, it still has to be shown that this anti-inflammatory effect of 17β-estradiol would translate into reduced cardiovascular morbidity and mortality. To date, results from intervention studies have yielded disappointing results. In primary prevention, in a larger sample of postmenopausal women of which this study cohort was a part, no effect was observed on carotid IMT, an established intermediate endpoint [24]. Similarly, in secondary prevention, no effect of HRT was seen on cardiovascular [49] and cerebrovascular [50] events, nor on progression of coronary artery atherosclerosis in women with established CHD [51]. To explain these results, a pro-inflammatory effect of HRT has been proposed [51]. In our study, although a sequential HRT regimen was used in which gestodene opposed 17β-estradiol, antiinflammatory effects were detectable. We hypothesize that the balance of pro- and antiinflammatory effects may very well be different among different HRT regimens. A systematic investigation using biomarkers of inflammatory processes might be able to identify a HRT regimen with a more promising profile than the ones already investigated in studies with clinical endpoints [49,51].

Limitations. Subjects and their physicians were not blinded with respect to treatment, because HRT is frequently accompanied by minor side effects that render valid blinding difficult. Conversely, blinding introduces a clinical care problem in subjects who experience vaginal bleeding. The reported effects of HRT on MCP-1 remained significant even after exploring potential confounders and intermediate steps (change of LDL, fibrinogen, and blood pressure); during the study, no cholesterol-lowering medication was commenced. It therefore is unlikely but can not completely excluded that subtle changes of lipoprotein levels and oxidation might have influenced the change in MCP-1 levels. Levels of circulating MCP-1 were measured in women after menopause only, therefore no direct comparison could be made with respect to premenopausal levels or levels in men. At the same time, we only investigated one low-dose estrogen regimen, therefore it remains to be shown whether higher doses of estrogen or addition of a different progestagen would affect MCP-1 levels differently.

In conclusion, a strong correlation was found between circulating MCP-1 levels and IMT in carotid and femoral arteries in postmenopausal women off HRT. MCP-1 is considered a marker of vascular inflammation, IMT a marker of atherosclerotic burden and risk for cardiovascular disease. HRT with 17β-estradiol reduced MCP-1 levels after 12 months. Six months after cessation of HRT, MCP-1 levels exceeded baseline levels. ICAM-1, VCAM-1, and E-selection were decreased by HRT as expected. 17β-estradiol may have an antiatherosclerotic effect by reducing MCP-1 and cellular adhesion molecules.

Time for primary review 34 days.


   Acknowledgements
 
This trial was supported by a grant from Münchener Universitätsgesellschaft, München, and by the Deutsche Forschungsgemeinschaft. The study medication was provided by Schering AG, Berlin. We are indebted to Rosemarie Kiefl for expert laboratory analysis.


   References
Top
 Abstract
 1. Introduction
 2. Methods
 3. Results
 4. Discussion
 References
 

  1. Ross R. Atherosclerosis — an inflammatory disease. N. Engl. J. Med. (1999) 340:115–126.[Free Full Text]
  2. Libby P., Ridker P.M. Novel inflammatory markers of coronary risk — theory versus practice. Circulation (1999) 100:1148–1150.[Free Full Text]
  3. Navab M., Imes S.S., Hama S.Y., et al. Monocyte transmigration induced by modification of low density lipoprotein in cocultures of human aortic wall cells is due to induction of monocyte chemotactic protein-1 synthesis and is abolished by high density lipoprotein. J. Clin. Invest. (1991) 88:2039–2046.[ISI][Medline]
  4. Boring L., Gosling J., Cleary M., Charo I.F. Decreased lesion formation in CCR2–/– mice reveals a role for chemokines in the initiation of atherosclerosis. Nature (1998) 394:894–897.[CrossRef][Medline]
  5. Gu L., Okada Y., Clinton S.K., et al. Absence of monocyte chemoattractant protein-1 reduces atherosclerosis in low density lipoprotein receptor-deficient mice. Mol. Cell. (1998) 2:275–281.[CrossRef][ISI][Medline]
  6. Ylä-Herttuala S., Lipton B.A., Rosenfeld M.E., et al. Expression of monocyte chemoattractant protein 1 in macrophage-rich areas of human and rabbit atherosclerotic lesions. Proc. Natl. Acad. Sci. U.S.A. (1991) 88:5252–5256.[Abstract/Free Full Text]
  7. Yu X., Dluz S., Graves D.T. Elevated expression of monocyte chemoattractant protein 1 by vascular smooth muscle cells in hypercholesterolemic primates. Proc. Natl. Acad. Sci. U.S.A. (1992) 89:6953–6957.[Abstract/Free Full Text]
  8. Nelken N.A., Coughlin S.R., Gordon D., Wilcox J.N. Monocyte chemoattractant protein-1 in human atheromatous plaques. J. Clin. Invest. (1991) 88:1121–1127.[ISI][Medline]
  9. Kovacs E.J., Faunce D.E., Ramer Quinn D.S., Mott F.J., Dy P.W., Frazier-Jessen M.R. Estrogen regulation of JE/MCP-1 mRNA expression in fibroblasts. J. Leukoc. Biol. (1996) 59:562–568.[Abstract]
  10. Frazier-Jessen M.R., Kovacs E.J. Estrogen modulation of JE/monocyte chemoattractant protein-1 mRNA expression in murine macrophages. J. Immunol. (1995) 154:1838–1845.[Abstract]
  11. Pervin S., Singh R., Rosenfeld M.E., Navab M., Chaudhuri G., Nathan L. Estradiol suppresses MCP-1 expression in vivo. Implications for atherosclerosis. Arterioscler. Thromb. Vasc. Biol. (1998) 18:1575–1582.[Abstract/Free Full Text]
  12. Hwang S.J., Ballantyne C.M., Sharrett A.R., et al. Circulating adhesion molecules VCAM-1, ICAM-1, and E-selectin in carotid atherosclerosis and incident coronary heart disease cases: the atherosclerosis risk in communities (ARIC) study. Circulation (1997) 96:4219–4225.[Abstract/Free Full Text]
  13. Blum A., Schenke W.H., Hathaway L. Effects of estrogen and the selective estrogen receptor modulator raloxifene on markers of inflammation in postmenopausal women. Am. J. Cardiol. (2000) 86:892–895.[CrossRef][ISI][Medline]
  14. Koh K.K., Cardillo C., Bui M.N., et al. Vascular effects of estrogen and cholesterol-lowering therapies in hypercholesterolemic postmenopausal women. Circulation (1999) 99:354–360.[Abstract/Free Full Text]
  15. Seljeflot I., Arnesen H., Hofstad A.E., Os I. Reduced expression of endothelial cell markers after long-term transdermal hormone replacement therapy in women with coronary artery disease. Thromb. Haemost. (2000) 83:944–948.[ISI][Medline]
  16. Burke G.L., Evans G.W., Riley W.A., et al. Arterial wall thickness is associated with prevalent cardiovascular disease in middle-aged adults. The atherosclerosis risk in communities (ARIC) study. Stroke (1995) 26:386–391.[Abstract/Free Full Text]
  17. Crouse J.R., Craven T.E., Hagaman A.P., Bond M.G. Association of coronary disease with segment-specific intimal-medial thickening of the extracranial carotid artery. Circulation (1995) 92:1141–1147.[Abstract/Free Full Text]
  18. Bots M.L., Hoes A.W., Koudstaal P.J., Hofman A., Grobbee D.E. Common carotid intima-media thickness and risk of stroke and myocardial infarction: the Rotterdam study. Circulation (1997) 96:1432–1437.[Abstract/Free Full Text]
  19. Salonen J.T., Salonen R. Ultrasonographically assessed carotid morphology and the risk of coronary heart disease. Arterioscler. Thromb. (1991) 11:1245–1249.[Abstract/Free Full Text]
  20. Hodis H.N., Mack W.J., LaBree L., et al. The role of carotid arterial intima-media thickness in predicting clinical coronary events. Ann. Intern. Med. (1998) 128:262–269.[Abstract/Free Full Text]
  21. Chambless L.E., Heiss G., Folsom A.R., et al. Association of coronary heart disease incidence with carotid arterial wall thickness and major risk factors: the atherosclerosis risk in communities (ARIC) study, 1987–1993. Am. J. Epidemiol. (1997) 146:483–494.[Abstract/Free Full Text]
  22. O'Leary D.H., Polak J.F., Kronmal R.A., Manolio T.A., Burke G.L., Wolfson S.K. Cardiovascular Health Study Collaborative Research Group. Carotid-artery intima and media thickness as a risk factor for myocardial infarction and stroke in older adults. N. Engl. J. Med. (1999) 340:14–22.[Abstract/Free Full Text]
  23. Hodis H.N., Mack W.J., LaBree L., et al. Reduction in carotid arterial wall thickness using lovastatin and dietary therapy: a randomized controlled clinical trial. Ann. Intern. Med. (1996) 124:548–556.[Abstract/Free Full Text]
  24. Angerer P., Störk S., Kothny W., Schmitt P., von Schacky C. The effect of oral postmenopausal hormone replacement therapy on atherosclerosis in carotid arteries — a randomized, controlled trial. Arterioscler. Thromb. Vasc. Biol. (2001) 21:262–268.[Abstract/Free Full Text]
  25. Wong M., Edelstein J., Wollman J., Bond M.G. Ultrasonic-pathological comparison of the human arterial wall. Verification of intima-media thickness. Arterioscler. Thromb. (1993) 13:482–486.[Abstract/Free Full Text]
  26. Okada M., Suzuki A., Mizuno K., et al. Effect of 17beta-estradiol and progesterone on migration of human monocyte THP-1 cells stimulated by minimally oxidized low density lipoprotein in vitro. Cardiovasc. Res. (1997) 34:529–535.[Abstract/Free Full Text]
  27. Hayashi T., Fukuto J.M., Ignarro L.J., Chaudhuri G. Basal release of nitric oxide from aortic rings is greater in female rabbits than in male rabbits: implications for atherosclerosis. Proc. Natl. Acad. Sci. U.S.A. (1992) 89:11259–11263.[Abstract/Free Full Text]
  28. Hishikawa K., Nakaki T., Marumo T., Suzuki H., Kato R., Saruta T. Up-regulation of nitric oxide synthase by estradiol in human aortic endothelial cells. FEBS Lett. (1995) 360:291–293.[CrossRef][ISI][Medline]
  29. Zeiher A.M., Fisslthaler B., Schray-Utz B., Busse R. Nitric oxide modulates the expression of monocyte chemoattractant protein 1 in cultured human endothelial cells. Circ. Res. (1995) 76:980–986.[Abstract/Free Full Text]
  30. Weiner C.P., Lizasoain I., Baylis S.A., Knowles R.G., Charles I.G., Moncada S. Induction of calcium-dependent nitric oxide synthases by sex hormones. Proc. Natl. Acad. Sci. U.S.A. (1994) 91:5212–5216.[Abstract/Free Full Text]
  31. Rollins B.J., Yoshimura T., Leonard E.J., Pober J.S. Cytokine-activated human endothelial cells synthesize and secrete a monocyte chemoattractant, MCP-1/JE. Am. J. Pathol. (1990) 136:1229–1233.[Abstract]
  32. Strieter R.M., Wiggins R., Phan S.H., et al. Monocyte chemotactic protein gene expression by cytokine-treated human fibroblasts and endothelial cells. Biochem. Biophys. Res. Commun. (1989) 162:694–700.[CrossRef][ISI][Medline]
  33. Ralston S.H., Russell R.G., Gowen M. Estrogen inhibits release of tumor necrosis factor from peripheral blood mononuclear cells in postmenopausal women. J. Bone Miner. Res. (1990) 5:983–988.[ISI][Medline]
  34. Han K.H., Han K.O., Green S.R., Quehenberger O. Expression of the monocyte chemoattractant protein-1 receptor CCR2 is increased in hypercholesterolemia. Differential effects of plasma lipoproteins on monocyte function. J. Lipid Res. (1999) 40:1053–1063.[Abstract/Free Full Text]
  35. Boring L., Gosling J., Chensue S.W., et al. Impaired monocyte migration and reduced type 1 (Th1) cytokine responses in C–C chemokine receptor 2 knockout mice. J. Clin. Invest. (1997) 100:2552–2561.[ISI][Medline]
  36. Kurihara T., Warr G., Loy J., Bravo R. Defects in macrophage recruitment and host defense in mice lacking the CCR2 chemokine receptor. J. Exp. Med. (1997) 186:1757–1762.[Abstract/Free Full Text]
  37. Soejima H., Ogawa H., Yasue H., et al. Angiotensin-converting enzyme inhibition reduces monocyte chemoattractant protein-1 and tissue factor levels in patients with myocardial infarction. J. Am. Coll. Cardiol. (1999) 34:983–988.[Abstract/Free Full Text]
  38. Baumann K.H., Hessel F., Larass I., et al. Dietary {omega}-3, {omega}-6, and {omega}-9 unsaturated fatty acids and growth factor and cytokine gene expression in unstimulated and stimulated monocytes. Arterioscler. Thromb. Vasc. Biol. (1999) 19:59–66.[Abstract/Free Full Text]
  39. von Schacky C., Angerer P., Kothny W., Theisen K., Mudra H. The effect of dietary {omega}-3 fatty acids on coronary atherosclerosis — a randomized, double-blind, placebo-controlled trial. Ann. Intern. Med. (1999) 130:554–562.[Abstract/Free Full Text]
  40. Romano M., Diomed L., Sironi M., et al. Inhibition of monocyte chemotactic protein-1 synthesis by statins. Lab. Invest. (2000) 80:1095–1100.[ISI][Medline]
  41. Fruebis J., Gonzalez V., Silvestre M., Palinski W. Effect of probucol treatment on gene expression of VCAM-1, MCP-1, and M-CSF in the aortic wall of LDL receptor-deficient rabbits during early atherogenesis. Arterioscler. Thromb. Vasc. Biol. (1997) 17:1289–1302.[Abstract/Free Full Text]
  42. Inadera H., Egashira K., Takemoto M., Ouchi Y., Matsushima K. Increase in circulating levels of monocyte chemoattractan protein-1 with aging. J. Interferon Cytokine Res. (1999) 19:1179–1182.[CrossRef][ISI][Medline]
  43. Capers Q., Alexander R.W., Lou P., et al. Monocyte chemoattractant protein-1 expression in aortic tissues of hypertensive rats. Hypertension (1997) 30:1397–1402.[Abstract/Free Full Text]
  44. Westendorp I.C., Veld B.A., Bots M.L., et al. Hormone replacement therapy and intima-media thickness of the common carotid artery: the Rotterdam study. Stroke (1999) 30:2562–2567.[Abstract/Free Full Text]
  45. Westendorp I.C., in't Veld B.A., Grobbee D.E. Hormone replacement therapy and peripheral arterial disease: the Rotterdam study. Arch. Intern. Med. (2000) 160:2498–2502.[Abstract/Free Full Text]
  46. Vogt M.T., Wolfson S.K., Kuller L.H. Segmental arterial disease in the lower extremities: correlates of disease and relationship to mortality. J. Clin. Epidemiol. (1993) 46:1267–1276.[CrossRef][ISI][Medline]
  47. Cybulsky M.I., Gimbrone M.A. Endothelial expression of a mononuclear leukocyte adhesion molecule during atherogenesis. Science (1991) 251:788–791.[Abstract/Free Full Text]
  48. Gimbrone M.A. Vascular endothelium: an integrator of pathophysiologic stimuli in atherosclerosis. Am. J. Cardiol. (1995) 75:67B–70B.[CrossRef][Medline]
  49. Hulley S., Grady D., Bush T., et al. Randomized trial of estrogen plus progestin for secondary prevention of coronary heart disease in postmenopausal women. J. Am. Med. Assoc. (1998) 280:805–813.
  50. Simon J.A., Hsia J., Cauley J.A., et al. Postmenopausal hormone therapy and risk of stroke: the heart and estrogen–progestin replacement study (HERS). Circulation (2001) 103:638–642.[Abstract/Free Full Text]
  51. Herrington D.M., Reboussin D.M., Brosnihan K.B., et al. Effects of estrogen replacement on the progression of coronary artery atherosclerosis. N. Engl. J. Med. (2000) 343:522–529.[Abstract/Free Full Text]

Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?


This article has been cited by other articles:


Home page
 Am J EpidemiolHome page
E. Wong, M. Freiberg, R. Tracy, and L. Kuller
Epidemiology of Cytokines: The Women On the Move through Activity and Nutrition (WOMAN) Study
Am. J. Epidemiol., August 15, 2008; 168(4): 443 - 453.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by Störk, S.
Right arrow Articles by Angerer, P.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Störk, S.
Right arrow Articles by Angerer, P.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?