Effect of hormone replacement therapy on nitric oxide bioactivity and monocyte chemoattractant protein-1 levels

Increased fat due to estrogen deficiency induces bone loss by elevating monocyte chemoattractant protein-1 (MCP-1) production

Ovariectomy (OVX)-induced estrogen withdrawal resulted in both bone loss and an increase in fat. We observed elevated osteoclast (OC) formation by bone marrow-derived macrophages treated with medium conditioned by fats from OVX mice, but not from sham-operated mice. Fats from OVX mice expressed and secreted higher levels of monocyte chemoattractant protein-1 (MCP-1) than those from sham-operated mice. Increased fat resulting from estrogen deficiency is thus responsible for bone loss due to enhanced OC formation, which is, at least partly, a consequence of elevated MCP-1 production.

Estrogen-dependent and C-C chemokine receptor-2-dependent pathways determine osteoclast behavior in osteoporosis

Understanding the mechanisms of osteoclastogenesis is crucial for developing new drugs to treat diseases associated with bone loss, such as osteoporosis. Here we report that the C-C chemokine receptor-2 (CCR2) is crucially involved in balancing bone mass. CCR2-knockout mice have high bone mass owing to a decrease in number, size and function of osteoclasts. In normal mice, activation of CCR2 in osteoclast progenitor cells results in both nuclear factor-kappaB (NF-kappaB) and extracellular signal-related kinase 1 and 2 (ERK1/2) signaling but not that of p38 mitogen-activated protein kinase or c-Jun N-terminal kinase. The induction of NF-kappaB and ERK1/2 signaling in turn leads to increased surface expression of receptor activator of NF-kappaB (RANK, encoded by Tnfrsf11a), making the progenitor cells more susceptible to RANK ligand-induced osteoclastogenesis. In ovariectomized mice, a model of postmenopausal osteoporosis, CCR2 is upregulated on wild-type preosteoclasts, thus increasing the surface expression of RANK on these cells and their osteoclastogenic potential, whereas CCR2-knockout mice are resistant to ovariectomy-induced bone loss. These data reveal a previously undescribed pathway by which RANK, osteoclasts and bone homeostasis are regulated in health and disease.

Epidemiology of cytokines: the Women On the Move through Activity and Nutrition (WOMAN) Study

Using multiplex technology, the authors investigated the laboratory and biologic variation of a panel of cytokines (interleukin (IL)-1a, IL-1 receptor antagonist, IL-4, IL-6, IL-8, IL-10, interferon-inducible protein-10, monocyte chemoattractant protein-1, and tumor necrosis factor-alpha) over 18 months and their relations to cardiovascular disease risk factors, hormone therapy, and weight loss. Data were obtained from the Woman On the Move through Activity and Nutrition (WOMAN) Study, a randomized clinical trial investigating the effect of nonpharmacologic interventions on subclinical atherosclerosis among overweight, postmenopausal women in Pennsylvania. The present analysis (February 2002-August 2005) comprised 290 women aged 52-62 years (mean age = 57 years). Most of the cytokines were detectable in a majority of the samples, and the between-individual biologic variation was greater than the within-individual biologic and laboratory variation. There was little association between use of hormone therapy at baseline or change in hormone therapy by 18 months and cytokine levels. Weight loss was associated with a decrease in levels of IL-1 receptor antagonist, IL-6, and C-reactive protein. The results suggest that a wide panel of cytokines may be measured simultaneously from one sample. There is large unexplained variability in cytokine levels that is probably due to genetic-environmental associations.

Hormonal replacement therapy after menopause is protective of disease activity in women with inflammatory bowel disease

BACKGROUND AND AIMS

The nature of inflammatory bowel disease (IBD) following menopause has not been previously studied. The aim of this study was to characterize the effect of menopause on disease activity and identify possible modifiers of disease activity.

METHODS

This was a retrospective study of women followed at the University of Chicago IBD Clinic. Disease activity was assessed using clinical scoring systems during the pre- and postmenstrual periods of subjects. Variables of interest included: history of smoking, use of oral contraceptives (OCP) prior to onset of menopause, and use of hormone replacement therapy (HRT).

RESULTS

Sixty-five women were included, 20 with ulcerative colitis and 45 with Crohn's disease. The median age of menopause was similar to historical controls. Twenty-three patients (35%) experienced active symptoms in the premenopausal time period and 25 patients (38%) had disease indices consistent with a flare within the first 2 yr after menopause (P > 0.05). There was no relation between those who had a pre- versus postmenstrual flare as a group (P > 0.05). However, there was a significant protective effect on disease activity with postmenopausal HRT use (hazard ratio [HR] 0.18, 95% confidence interval [CI] 0.04-0.72). There was also a dose-response effect noted with an HR with longer duration of use (0.20, 0.07-0.65).

CONCLUSIONS

The likelihood of having a flare postmenopause is not different from having it premenopause. HRT, however, may provide a protective effect for disease activity in the postmenopausal period. The anti-inflammatory effects of estrogen may be the mechanism for this observation.

Low-dose continuous combinations of hormone therapy and biochemical surrogate markers for vascular tone and inflammation: transdermal versus oral application

OBJECTIVE

To compare the effects of low-dose transdermal estradiol (E2)/norethisterone acetate (NETA) patches (Estalis 25/125) with low-dose oral E2/NETA (Activelle) on cardiovascular biochemical markers after 12 and 52 weeks of treatment in postmenopausal women with intact uteri.

DESIGN

Participants were randomly assigned to receive either transdermal E2/NETA (delivering daily doses of 25 microg E2 and 125 microg NETA, applied every 3-4 d) or oral E2/NETA (1 mg E2 and 0.5 mg NETA, given daily) in this open-label study. The following markers or their stable metabolites in serum or urine were assessed: P-selectin, intercellular adhesion molecule-1, vascular cell adhesion molecule-1, monocyte chemoattractant protein-1, matrix metalloproteinase-9, homocysteine, cyclic guanosine monophosphate, serotonin, prostacyclin, thromboxane, and urodilatin.

RESULTS

Significant decreases were found for P-selectin, intercellular adhesion molecule-1, monocyte chemoattractant protein-1, and homocysteine for both hormone therapy (HT) regimens compared with baseline. Matrix metalloproteinase-9 was increased only by oral HT. The urinary concentrations of cyclic guanosine monophosphate, the ratio of prostacyclin to thromboxane metabolite, and the serotonin metabolite were significantly increased for both HT application modes, although the oral treatment showed a significantly greater increase than the transdermal one with respect to baseline. Urodilatin excretion was increased only by the oral regimen.

CONCLUSIONS

Low-dose transdermal and oral HTs using E2 and NETA elicit favorable effects on cardiovascular biochemical markers. For most markers the magnitude of changes found were similar with respect to baseline; however, in some cases oral HT led to a significantly greater change, whereas in other cases the transdermal formulations seemed to provide greater benefits. Whether these differences may be attributed to the different administration routes or to different pharmacokinetic properties remains an open question. Overall low-dose transdermal HT seems to provoke the same benefit on the cardiovascular system as oral HT, as suggested by the results on vascular markers.

Monocyte chemotactic protein-1 secreted by primary breast tumors stimulates migration of mesenchymal stem cells

PURPOSE

Major barriers to effective adenovirus-based gene therapy include induction of an immune response and tumor-specific targeting of vectors. The use of mesenchymal stem cells (MSC) as systemic delivery vehicles for therapeutic genes has been proposed as a result of their combined ability to home in on the tumor site and evade the host immune response. This study is aimed at investigating factors mediating homing of human MSCs to breast cancer primary cultures and cell lines in vitro and in vivo.

EXPERIMENTAL DESIGN

Fluorescently labeled MSCs were given to mice bearing breast cancer xenografts, and tumor tissue was harvested to detect MSC engraftment. MSC migration in response to primary breast tumors in vitro was quantified, and chemokines secreted by tumor cells were identified. The role of monocyte chemotactic protein-1 (MCP-1) in cell migration was investigated using antibodies and standards of the chemokine. Serum MCP-1 was measured in 125 breast cancer patients and 86 healthy controls.

RESULTS

Engrafted MSCs were detected in metastatic breast tumors in mice after systemic administration. There was a significant increase in MSC migration in response to primary breast tumor cells in vitro (6-fold to 11-fold increase). Tumor explants secreted a variety of chemokines including GROalpha, MCP-1, and stromal cell-derived factor-1alpha. An MCP-1 antibody caused a significant decrease (37-42%) in MSC migration to tumors. Serum MCP-1 levels were significantly higher in postmenopausal breast cancer patients than age-matched controls (P < 0.05).

CONCLUSIONS

These results highlight a role for tumor-secreted MCP-1 in stimulating MSC migration and support the potential of these cells as tumor-targeted delivery vehicles for therapeutic agents.

Circulating chemoattractants RANTES, negatively related to endogenous androgens, and MCP-1 are differentially suppressed by hormone therapy and raloxifene

BACKGROUND

The cardinal role of chronic inflammation in the development of atherosclerosis is increasingly being recognized. Estrogens may prevent the evolution of atherosclerosis by suppressing immune response. Furthermore, the conflicting reports on the cardiovascular effects of hormone therapy between observational and clinical trials have triggered interest on the effect of alternative therapies on the cardiovascular system.

OBJECTIVE

The aim of this study was to assess the effect of estrogen, estrogen-progestin, tibolone and raloxifene therapy on circulating markers of chemotaxis in healthy postmenopausal women.

METHODS

Eighty-eight postmenopausal women aged 44-62 years were randomly allocated to daily: (1) conjugated equine estrogens 0.625 mg (CEE), (2) 17beta-estradiol 1mg plus norethisterone acetate 0.5mg (E(2)/NETA), (3) tibolone 2.5mg, (4) raloxifene HCl 60 mg or (5) no treatment. Serum monocyte chemoattractant protein-1 (MCP-1) and regulated upon activation, normal T-cell expressed and secreted (RANTES) were measured at baseline and at 3 months.

RESULTS

Endogenous testosterone and free androgen index (FAI) correlated negatively, while SHBG correlated positively with serum RANTES (testosterone: r=-0.27, p=0.033; FAI: r=-0.43, p=0.004: SHBG: r=0.34, p=0.026). Serum MCP-1 decreased significantly in the CEE group (baseline 125.3+/-51 pg/ml, 3 months 84.5+/-36.1 pg/ml, p=0.043), while no difference was detected between baseline and post-treatment levels in the other groups. Furthermore, a significant decrease in serum RANTES was observed at the end of 3 months only in the E2/NETA and the raloxifene group (E2/NETA baseline 8690.6+/-3880.0 pg/ml, 3 months 6894.0+/-1720.0 pg/ml, p=0.007; raloxifene baseline 9042.4+/-3765.6 pg/ml, 3 months 6718.1+/-2366.2 pg/ml, p=0.011).

CONCLUSION

Endogenous androgens may suppress chemotactic response. Postmenopausal hormone therapy and raloxifene may inhibit the expression of chemoattractant molecules and thus attenuate inflammation. The relevance of these findings in terms of clinically established caridoprotection remains to be clarified.

Modulating role of estradiol on arginase II expression in hyperlipidemic rabbits as an atheroprotective mechanism

We evaluated the effects of a 0.5% cholesterol-enriched diet (HCD) on nitric-oxide synthase (NOS) and arginase expression and the modulating role of 17beta-estradiol (E(2)) on this phenomenon. Thirty oopherectomized rabbits were divided into three groups and treated for 15 weeks. Group I received normal chow; group II, HCD; and group III, HCD plus E(2) pellets. Animals in group II showed an increase in plasma lipids, and they demonstrated atheromatous lesions as well as expression of arginase I and II accompanied by a significant number of BrdU-positive cells in endothelial cells and intimal muscle cells, suggestive of an increase in cellular proliferation. There was significant expression of inducible NOS and increased staining of nitrotyrosine-positive areas. These were not observed in group I animals. In both groups, E(2) levels were low. In group III animals, E(2) supplementation led to a decrease in atheromatous lesions and BrdU-positive cells and reduced expression of both inducible NOS and arginase I and II accompanied by a decrease in nitrotyrosine staining. E(2) levels were increased. Our results suggest that E(2) was responsible for these effects, despite the animals being hyperlipidemic, similar to those in group II. Because arginase is responsible for cell proliferation by converting l-arginine to polyamines, our results indicate that expression of arginase may play an important role in cellular proliferation in atherosclerosis, and inhibition of arginase expression by E(2) may be another potential mechanism in attenuating atherogenesis.

Biochemical markers surrogating on vascular effects of sex steroid hormones

The main mechanism of possible cardioprotection by estrogens appears to be a direct effect on the vasculature, resulting in an improvement of endothelial function and inhibition of atherogenesis. Numerous observational and experimental studies have demonstrated a positive correlation between estrogens and various biochemical markers surrogating direct vascular effects. In general, most markers are influenced in a similar way by oral and transdermal hormone therapy, although oral therapy may have a faster and more pronounced effect. The main difference between oral and transdermal administration may be confined to markers that are mainly or exclusively produced in the liver. Clinical studies demonstrate that progestogen addition can have an impact on the beneficial estrogen-induced changes of biochemical markers. Concerning the effects of tibolone, inconsistent data have been found. Overall, tibolone-induced beneficial changes on the various biochemical markers appear to be less marked compared with those of hormone therapy. The few data available on the direct effects of androgens on the vascular wall indicate a less favorable action of androgens on biochemical markers than of estrogens. The practical relevance of marker measurements is currently under discussion. Although evidence strongly supports some of these markers as predictors of acute events, it remains to be established whether modifying circulating levels of these markers will influence outcomes.

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.

Tissue-specific effect of estradiol on endothelial cell-dependent lymphocyte recruitment

Estrogen profoundly affects onset and severity of many immune-mediated diseases. In our murine model of drug-induced autoimmunity, female-specific, estrogen-dependent increase in splenic lymphocyte homing was directly implicated in increased disease severity. The present study evaluated the effect of estradiol on microvascular endothelial cells from the spleen compared to endothelial cells from the dermis, which has no disease manifestation in this model. Estradiol increased spleen endothelial cell estrogen receptor (ER) alpha 2.9-fold and decreased estrogen receptor beta 2.1-fold while decreasing both receptors on dermal cells. Estradiol enhanced adhesion of D10 cells to spleen but not dermal endothelial cells 1.53-fold (P < 0.001), an increase that was inhibited by antibodies to VCAM-1 and ICAM-1, and by the estrogen receptor antagonists tamoxifen and ICI 182,780. Estradiol induced greater VCAM-1 expression on spleen than dermal endothelial cells (P < 0.05). Estradiol increased spleen endothelial cell estrogen receptor alpha 2.9-fold and decreased estrogen receptor beta 2.1-fold while decreasing both receptors on the dermal cells. Estrogen specifically and preferentially promoted spleen chemokine protein expression for MCP-1 and MCP-3, while having no effect on dermal protein expression for these chemokines. Estradiol-mediated effects on splenic chemokines were abrogated by tamoxifen and ICI 182,780. The gender-specific increase in lymphocyte homing to spleen may be attributable, at least in part, to tissue-specific estrogen-mediated effects on microvascular endothelial cells.

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.

Estrogen, inflammation and cardiovascular risk in women: a critical appraisal

The widely shared enthusiasm about the cardioprotective potential of estrogenic compounds has come to an abrupt halt since randomized trials failed to show a cardiovascular risk reduction in postmenopausal women. This was unexpected because observational studies had strongly suggested that hormone replacement therapy would reduce the incidence of cardiovascular disease. Inflammatory activity is considered central in atherogenesis and atherosclerosis progression. Thus, parts of the striking discrepancy between observational and randomized data have been attributed to an estrogen-mediated adverse effect on inflammation. Here, we review the current clinical evidence with respect to the inflammation-modulating effects of different estrogenic compounds as one potential explanatory factor for these divergent findings. We conclude that it is still unclear whether estrogen-modulated inflammation is an important biological factor determining clinical outcome or a mere epiphenomenon.

Estrogen decreases chemokine levels in murine mammary tissue: implications for the regulatory role of MIP-1 alpha and MCP-1/JE in mammary tumor formation

Estrogen contributes to the development of breast cancer through mechanisms that are not completely understood. Estrogen influences the function of immune effector cells, primarily through alterations in cytokine expression. Chemokines are proinflammatory cytokines that attract various immune cells to the site of tissue injury or inflammation, and activate many cell types, including T lymphocytes and monocytes. As an initial step toward ultimately determining whether regulation of chemokine expression and/or biological activity by estrogen could potentially be a contributing factor to the development and progression of mammary tumors, we evaluated the effect of estrogen on the expression of specific chemokines in murine mammary tissue. We also evaluated whether exposure of female mice to various chemokines could alter the growth of mammary tumors in the presence of estrogen. We report here that estrogen significantly decreases levels of the chemokines MIP-1alpha and MCP-1/JE in murine mammary tissue. Co-treatment with 4-hydroxytamoxifen partially reverses the suppressive effect of estrogen on MIP-1alpha levels. Estrogen increases the growth of CCL- 51 cell-based tumors in the mammary glands of female mice. Co-treatment with the chemokine MIP-1alpha or MCP- 1/JE substantially decreases the ability of estrogen to stimulate the formation of CCL-51 cell-based tumors. Our results show that estrogen might influence the bioactivity of specific chemokines through alteration of chemokine expression in mammary tissue, and further suggest that decreases in murine chemokines evoked by estrogen exposure could contribute to the promotion of mammary tumor growth.

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.

Effects of estrogen on the vascular system

The cardiovascular protective actions of estrogen are partially mediated by a direct effect on the vessel wall. Estrogen is active both on vascular smooth muscle and endothelial cells where functionally competent estrogen receptors have been identified. Estrogen administration promotes vasodilation in humans and in experimental animals, in part by stimulating prostacyclin and nitric oxide synthesis, as well as by decreasing the production of vasoconstrictor agents such as cyclooxygenase-derived products, reactive oxygen species, angiotensin II, and endothelin-1. In vitro, estrogen exerts a direct inhibitory effect on smooth muscle by activating potassium efflux and by inhibiting calcium influx. In addition, estrogen inhibits vascular smooth muscle cell proliferation. In vivo, 17beta-estradiol prevents neointimal thickening after balloon injury and also ameliorates the lesions occurring in atherosclerotic conditions. As is the case for other steroids, the effect of estrogen on the vessel wall has a rapid non-genomic component involving membrane phenomena, such as alteration of membrane ionic permeability and activation of membrane-bound enzymes, as well as the classical genomic effect involving estrogen receptor activation and gene expression.

17Beta-estradiol inhibits the adhesion of leukocytes in TNF-alpha stimulated human endothelial cells by blocking IL-8 and MCP-1 secretion, but not its transcription

Inflammation, and especially mononuclear cell adhesion to endothelium, is an important physiopathological component of atherosclerosis. Since coronary heart disease in women of reproductive age and/or with estrogen replacement therapy is reduced, our aim was to determine if 17beta-estradiol had a regulatory effect on the adhesion of lymphocytes to the endothelium. We performed U-937 cells adhesion assays in TNF-alpha-stimulated HUVECs, and we also quantitated IL-8 and MCP-1 in culture supernatants, in the presence or not of 17beta-estradiol. The presence of alpha- and beta-estrogen receptors was determined by Western blot and RT-PCR, respectively, whereas the transcription of both chemokines was evaluated by RT-PCR. The results showed a 35% decrease in the adhesion of U-937 monocyte cells to TNF-alpha-stimulated HUVECs, and a 54% and 65% inhibition of TNF-alpha-induced IL-8 and MCP-1 secretion by physiological and physiologically high doses of 17beta-estradiol. The hormone did not affect the transcription of both chemokine genes. Tamoxifen reverted the inhibitory effect induced by 17beta-estradiol. In conclusion, 17beta-estradiol modifies the adhesion of leukocytes to endothelial cells by inhibiting the secretion, but not the gene transcription, of proinflammatory chemokines.