Estrogen Modulates Inflammatory Mediator Expression and Neutrophil Chemotaxis in Injured Arteries

Estrogen and mechanisms of vascular protection

Estrogen has antiinflammatory and vasoprotective effects when administered to young women or experimental animals that appear to be converted to proinflammatory and vasotoxic effects in older subjects, particularly those that have been hormone free for long periods. Clinical studies have raised many important questions about the vascular effects of estrogen that cannot easily be answered in human subjects. Here we review cellular/molecular mechanisms by which estrogen modulates injury-induced inflammation, growth factor expression, and oxidative stress in arteries and isolated vascular smooth muscle cells, with emphasis on the role of estrogen receptors and the nuclear factor-kappaB (NFkappaB) signaling pathway, as well as evidence that these protective mechanisms are lost in aging subjects.

Gender differences in acute cadmium-induced systemic inflammation in rats

OBJECTIVE

To examine the presence of gender differences in pro-inflammatory potential of cadmium in rats by comparing systemic inflammatory response to acute cadmium intoxication in animals of the two sexes.

METHODS

Basic aspects of this response were evaluated, including plasma levels of inflammatory cytokines tumor necrosis factor (TNF) and interleukin-6 (IL-6) and of major rat acute phase protein alpha 2-macroglobulin (alpha2-M), as soluble indicators of inflammation, and the number and activity of peripheral blood leukocytes, as cellular indicators of inflammation.

RESULTS

Differential increases of IL-6 and alpha2-M (higher in males than in females) in peripheral blood cell counts and types (leukocytosis and shift in the ratio of granulocytes to lymphocytes more pronounced in males vs females) and in levels of neutrophil priming (higher in males vs females) were noted.

CONCLUSION

The data document a more intense inflammatory response to cadmium administration in males. The sex differences in inflammatory effects of cadmium might be taken into consideration in studying the toxicity of this heavy metal.

Potential role of high-mobility group box 1 in cystic fibrosis airway disease

RATIONALE

High-mobility group box 1 (HMGB1) is a potent inflammatory mediator elevated in sepsis and rheumatoid arthritis, although its role in cystic fibrosis (CF) lung disease is unknown.

OBJECTIVES

To determine whether HMGB1 contributes to CF lung inflammation, including neutrophil chemotaxis and lung matrix degradation.

METHODS

We used sputum and serum from subjects with CF and a Scnn1b-transgenic (Scnn1b-Tg) mouse model that overexpresses beta-epithelial Na(+) channel in airways and mimics the CF phenotype, including lung inflammation. Human secretions and murine bronchoalveolar lavage fluid (BALF) was assayed for HMGB1 by Western blot and ELISA. Neutrophil chemotaxis was measured in vitro after incubation with human neutrophils. The collagen fragment proline-glycine-proline (PGP) was measured by tandem mass spectroscopy.

MEASUREMENTS AND MAIN RESULTS

HMGB1 was detected in CF sputum at higher levels than secretions from normal individuals. Scnn1b-Tg mice had elevated levels of HMGB1 by Western blot and ELISA. We demonstrated that dose-dependent chemotaxis of human neutrophils stimulated by purified HMGB1 was partially dependent on CXC chemokine receptors and that this could be duplicated in CF sputum and BALF from Scnn1b-Tg mice. Neutralization by anti-HMGB1 antibody, in both the sputum and BALF-reduced chemotaxis, which suggested that HMGB1 contributed to the chemotactic properties of these samples. Intratracheal administration of purified HMGB1 induced neutrophil influx into the airways of mice and promoted the release of PGP. PGP was also elevated in Scnn1b-Tg mice and CF serum.

CONCLUSIONS

HMGB1 expression contributes to pulmonary inflammation and lung matrix degradation in CF airway disease and deserves further investigation as a biomarker and potential therapeutic target.

Sex differences in stroke

Increasing evidence suggests that sex differences exist in the etiology, presentation, treatment, and outcome from stroke. The reasons for these sex disparities are becoming increasingly explored, but large gaps still exist in our knowledge. Experimental studies over the past several years have demonstrated intrinsic sex differences both in vivo and in animal models which may have relevance to our understanding of stroke in clinical populations. A greater understanding of the differences and similarities between males and females with respect to the risk factors, pathophysiology, and response to stroke will facilitate the design of future clinical trials and enhance the development of treatment strategies to improve stroke care in both sexes. This article reviews the current literature on sex differences in stroke with an emphasis on the clinical data, incorporating an analysis of bench research as it pertains to the bedside.

The proteasome inhibitor bortezomib inhibits intimal hyperplasia of autologous vein grafting in rat model

OBJECTIVE

Increasing evidence indicates that inflammation plays an important role in intimal hyperplasia (IH) induced by autologous vein grafts. The proteasome inhibitor bortezomib shows anti-inflammatory effects, so we used an autologous vein transplantation model to test whether bortezomib inhibits neointimal formation in transplant-induced vasculopathy.

MATERIALS AND METHODS

We subjected 88 rats to autologous external jugular vein grafting surgery randomly assigned to be treated with bortezomib or vehicle. After 24 or 72 hours, rats were humanely killed and vein grafts processed for real-time RT-PCR (24 and 72 hours), ELISA (24 hours), or neutrophil chemotaxis assay (24 hours). Subsequently, rats were humanely killed at 1 and 2 weeks after grafting with samples processed for morphometric analysis.

RESULTS

Bortezomib significantly inhibited IH at 2 weeks compared with untreated controls (P < .05). Expression of mRNA for vascular cell adhesion molecule-1, intercellular adhesion molecule-1, cytokine-induced neutrophil chemoattractant 2beta, monocyte chemoattractant-1, interleukin (IL)-1, IL-6, and tumor necrosis factor-alpha markedly increased in injured vessels during the first day after surgery declining over the following 3 days. Bortezomib significantly attenuated gene expression and protein levels of most inflammatory mediators (P < .05), simultaneously inhibiting neutrophil chemotactic activity of vessel homogenates.

CONCLUSIONS

Bortezomib inhibited neointimal formation at least partially by attenuating the inflammatory response in transplant-induced vasculopathy. It may become a novel vasoprotective agent in the clinical field.

Vascular actions of estrogens: functional implications

The impact of estrogen exposure in preventing or treating cardiovascular disease is controversial. But it is clear that estrogen has important effects on vascular physiology and pathophysiology, with potential therapeutic implications. Therefore, the goal of this review is to summarize, using an integrated approach, current knowledge of the vascular effects of estrogen, both in humans and in experimental animals. Aspects of estrogen synthesis and receptors, as well as general mechanisms of estrogenic action are reviewed with an emphasis on issues particularly relevant to the vascular system. Recent understanding of the impact of estrogen on mitochondrial function suggests that the longer lifespan of women compared with men may depend in part on the ability of estrogen to decrease production of reactive oxygen species in mitochondria. Mechanisms by which estrogen increases endothelial vasodilator function, promotes angiogenesis, and modulates autonomic function are summarized. Key aspects of the relevant pathophysiology of inflammation, atherosclerosis, stroke, migraine, and thrombosis are reviewed concerning current knowledge of estrogenic effects. A number of emerging concepts are addressed throughout. These include the importance of estrogenic formulation and route of administration and the impact of genetic polymorphisms, either in estrogen receptors or in enzymes responsible for estrogen metabolism, on responsiveness to hormone treatment. The importance of local metabolism of estrogenic precursors and the impact of timing for initiation of treatment and its duration are also considered. Although consensus opinions are emphasized, controversial views are presented to stimulate future research.

Transforming growth factor-beta signaling mediates hypoxia-induced pulmonary arterial remodeling and inhibition of alveolar development in newborn mouse lung

Hypoxia causes abnormal neonatal pulmonary artery remodeling (PAR) and inhibition of alveolar development (IAD). Transforming growth factor (TGF)-beta is an important regulator of lung development and repair from injury. We tested the hypothesis that inhibition of TGF-beta signaling attenuates hypoxia-induced PAR and IAD. Mice with an inducible dominant-negative mutation of the TGF-beta type II receptor (DNTGFbetaRII) and nontransgenic wild-type (WT) mice were exposed to hypoxia (12% O(2)) or air from birth to 14 days of age. Expression of DNTGFbetaRII was induced by 20 microg/g ZnSO(4) given intraperitoneally daily from birth. PAR, IAD, cell proliferation, and expression of extracellular matrix (ECM) proteins were assessed. In WT mice, hypoxia led to thicker, more muscularized resistance pulmonary arteries and impaired alveolarization, accompanied by increases in active TGF-beta and phosphorylated Smad2. Hypoxia-induced PAR and IAD were greatly attenuated in DNTGFbetaRII mice given ZnSO(4) compared with WT control mice and DNTGFbetaRII mice not given ZnSO(4). The stimulatory effects of hypoxic exposure on pulmonary arterial cell proliferation and lung ECM proteins were abrogated in DNTGFbetaRII mice given ZnSO(4). These data support the conclusion that TGF-beta plays an important role in hypoxia-induced pulmonary vascular adaptation and IAD in the newborn animal model.

Increased protein O-GlcNAc modification inhibits inflammatory and neointimal responses to acute endoluminal arterial injury

Inflammation plays a major role in vascular disease. We have shown that leukocyte infiltration and inflammatory mediator expression contribute to vascular remodeling after endoluminal injury. This study tested whether increasing protein O-linked-N-acetylglucosamine (O-GlcNAc) levels with glucosamine (GlcN) and O-(2-acetamido-2-deoxy-d-glucopyranosylidene) amino-N-phenylcarbamate (PUGNAc) inhibits acute inflammatory and neointimal responses to endoluminal arterial injury. Ovariectomized rats were treated with a single injection of GlcN (0.3 mg/g ip), PUGNAc (7 nmol/g ip) or vehicle (V) 2 h before balloon injury of the right carotid artery. O-GlcNAc-modified protein levels decreased markedly in injured arteries of V-treated rats at 30 min, 2 h, and 24 h after injury but returned to control (contralateral uninjured) levels after 14 days. Both GlcN and PUGNAc increased O-GlcNAc-modified protein levels in injured arteries compared with V controls at 30 min postinjury; the GlcN-mediated increase persisted at 24 h but was not evident at 14 days. Proinflammatory mediator expression increased markedly after injury and was reduced significantly (30-50%) by GlcN and PUGNAc. GlcN and PUGNAc also inhibited infiltration of neutrophils and monocytes in injured arteries. Chronic (14 days) treatment with GlcN reduced neointima formation in injured arteries by 50% compared with V controls. Acute GlcN and PUGNAc treatment increases O-GlcNAc-modified protein levels and inhibits acute inflammatory responses in balloon-injured rat carotid arteries; 14 day GlcN treatment inhibits neointima formation in these vessels. Augmenting O-GlcNAc modification of proteins in the vasculature may represent a novel anti-inflammatory and vasoprotective mechanism.

Relation of adult-onset asthma to coronary heart disease and stroke

Asthma was associated with atherosclerotic disease in several studies, with evidence that this association may be limited to women. However, most previous studies failed to account for the heterogeneity of asthma subtypes. We previously reported increased carotid intima-medial thickness in women with adult-onset asthma. In this study, the association of adult- and child-onset asthma with incident coronary heart disease (CHD) and stroke were examined. Subjects were classified according to self-report of physician-diagnosed asthma and age of asthma onset. Cox proportional hazards models were used to test the association of adult- and child-onset asthma with incident CHD and stroke, testing for gender interaction. Subanalysis was also performed using only never smokers. Women with adult-onset asthma experienced a 2-fold increase in incident CHD and stroke that was independent of other risk factors, including smoking, body mass index, and physical activity, and persisted when analysis was restricted to never smokers. No significant association was found in women with child-onset asthma or in men. In conclusion, adult-onset asthma may be a significant risk factor for CHD and stroke in women, but not men.

Sex differences and estrogen modulation of the cellular immune response after injury

Cell-mediated immunity is extremely important for resolution of infection and for proper healing from injury. However, the cellular immune response is dysregulated following injuries such as burn and hemorrhage. Sex hormones are known to regulate immunity, and a well-documented dichotomy exists in the immune response to injury between the sexes. This disparity is caused by differences in immune cell activation, infiltration, and cytokine production during and after injury. Estrogen and testosterone can positively or negatively regulate the cellular immune response either by aiding in resolution or by compounding the morbidity and mortality. It is apparent that the hormonal dysregulation is dependent not only on the type of injury sustained but also the amount of circulating hormones. Therefore, it may be possible to design sex-specific therapies to improve immunological function and patient outcome.

Role of matrix metalloproteinase-2 in newborn mouse lungs under hypoxic conditions

Hypoxia impairs normal neonatal pulmonary artery remodeling and alveolar development. Matrix metalloproteinase-2 (MMP-2), which regulates collagen breakdown, is important during development. Our objective was to test the hypothesis that hypoxia attenuates the normal postnatal increase in MMP-2 and evaluate alveolar development and pulmonary arterial remodeling in Mmp2 mice. C57BL/6 wild-type (WT), Mmp2, Mmp2, and MMP-inhibited (with doxycycline) mice were exposed to hypoxia (12% O2) or air from birth to 2 wk of age. Pulmonary arterial remodeling, alveolar development, and vascular collagen and elastin were evaluated. MMP-2 was estimated by quantitative real-time polymerase chain reaction, enzyme-linked immunosorbent assay, immunohistochemistry, and zymography. We observed that 1) in WT mice, hypoxia led to thicker-walled pulmonary arteries and impaired alveolarization, accompanied by decreased MMP-2 and increased tissue inhibitor of metalloproteinases-2 (TIMP-2); 2) Mmp2 mice in air had thicker-walled arteries, impaired alveolarization, and increased perivascular collagen and elastin compared with WT; 3) hypoxia further inhibited alveolarization but did not alter arterial thickening in Mmp2 mice. Mmp2 and MMP-inhibited mice also had thicker-walled arteries than WT in air, but alveolarization was not different. We conclude that hypoxia reduces the postnatal MMP-2 increase in the lung, which may contribute to abnormal pulmonary arterial remodeling and impaired alveolarization.

Redox features of the cell: a gender perspective

Reactive oxygen and nitrogen species have been implicated in diverse subcellular activities, including cell proliferation,differentiation and, in some instances, cell injury and death. The implications of reactive species inhuman pathology have also been studied in detail. However, although the role of free radicals in the pathogenesis of human diseases has been extensively analyzed in different systems (i.e., in vitro, ex vivo, and in vivo),it is still far from elucidated. In particular, the possible role of gender 4 differences in human pathophysiology associated with reactive species is a promising new field of investigation. Although the complex scenario this presents is still incomplete, important gender-associated "redox features" of cells have already been described in the literature. Here we summarize the different aspects of redox-associated molecules and enzymes in regard to gender differences in terms of the intracellular production and biochemical activity of reactive species. These are often associated with the pathogenetic mechanisms underlying several human morbidities(e.g., degenerative diseases) and can represent a specific target for new pharmacologic strategies. Gender differences may thus pose an important challenge for future studies aimed at the clinical management of diseases characterized by a redox imbalance.

Role of sex hormones in allergic inflammation in mice

BACKGROUND

A number of clinical studies have documented both a pro- and anti-inflammatory role for sex hormones in the context of lung inflammation and worsening of asthma.

OBJECTIVE

To determine the role of sex hormones in a murine model of allergic inflammation and airway hyper-responsiveness (AHR) induced by ovalbumin (OVA).

METHODS

Female BALB/c were sensitized to OVA on days 0 and 7 and subsequently challenged on day 14 over a 3-day period. Mice had their ovaries removed either 7 days before or 8 days after the first OVA injection on day 0. Pulmonary eosinophilia and AHR were measured 24 h following the last antigen challenge. In other experiments, ovariectomized mice (Ovx) were pre-treated with oestradiol benzoate. In further studies, the effect of the oestradiol antagonist tamoxifen on allergic inflammation in intact mice was evaluated. Spleens from all groups were collected for proliferation assays and measurement of cytokine release.

RESULTS

Removal of the ovaries 7 days before sensitization to OVA significantly inhibited lung eosinophilia and IL-5 levels in lung lavage. Furthermore, airway reactivity (maximum response) but not sensitivity (PC100) to methacholine were significantly reduced in these mice. Proliferation of spleen cells and release of IL-5 collected from Ovx mice was significantly attenuated compared with spleen cells obtained from non-Ovx mice. Ovx mice treated with oestradiol benzoate presented partially restored levels of eosinophils and IL-5 in sensitized mice. Moreover, pharmacological antagonism of the effect of endogenous oestrogen with tamoxifen significantly reduced the number of eosinophils in the lung of intact sensitized mice, reproducing the effect of ovariectomy, and suggested a role for oestrogen in the process of antigen sensitization in female mice. In contrast, removal of ovaries 8 days after the first OVA injection failed to alter significantly pulmonary eosinophilia or AHR to methacholine in comparison with non-Ovx mice. Moreover, removal of the ovaries 8 days after the sensitization period induced a significant increase in levels of IL-5 in lung fluid. Spleen cells collected from these mice also had a significantly higher proliferation index and production of IL-5 in response to OVA than non-Ovx mice. Treatment with oestradiol benzoate partially reduced levels of eosinophils present in the lung of Ovx mice, supporting an anti-inflammatory role of sex hormones during the effector phase of the response to inhaled antigen.

CONCLUSION

Sex hormones play a dual role in regulating allergic lung inflammation in mice.

Pulse pressure is an age-independent predictor of stroke development after cardiac surgery

Chronologic age is a strong predictor of adverse outcomes after cardiac surgery. The variability in age-related cardiovascular changes suggests that age may not be the most accurate predictor of adverse perioperative outcomes. Vascular stiffness has emerged as an important surrogate of vascular aging. In a retrospective review, we investigated the value of vascular stiffness, as assessed by brachial pulse pressure (PP) measurements, in predicting stroke in 703 patients (63.4% men and 36.6% women). Patients were followed for 348+/-215 days after cardiac surgery. We used a multivariable logistic model and unadjusted and adjusted Cox proportional-hazard models to assess the probability of stroke and the hazards of stroke over time. Stroke patients had a significantly higher PP (81.2 mm Hg versus 64.5 mm Hg; P=0.0006). In the logistic regression model, PP was an independent predictor of stroke development (unadjusted odds ratio: 1.35; 95% CI: 1.13 to 1.62, for every 10-mm Hg increase in PP; P=0.001). In the unadjusted and adjusted Cox models, PP again predicted stroke (hazard ratio: 1.32; 95% CI: 1.12 to 1.57; hazard ratio: 2.62; 95% CI: 1.49 to 4.60, respectively; P=0.001 for both) for every 10 mm Hg increase in PP. Age, gender, and diabetes were not independent predictors of stroke. Ejection fraction was inversely related to stroke in the adjusted model. Kaplan-Meier estimates and corresponding log-rank test indicated that the probability of stroke-free survival function was significantly lower (P=0.0067) in patients with PP >72 mm Hg versus <72 mm Hg. This analysis suggests that indices of vascular stiffness could be important predictors of neurologic complications.

The complex role of estrogens in inflammation

There is still an unresolved paradox with respect to the immunomodulating role of estrogens. On one side, we recognize inhibition of bone resorption and suppression of inflammation in several animal models of chronic inflammatory diseases. On the other hand, we realize the immunosupportive role of estrogens in trauma/sepsis and the proinflammatory effects in some chronic autoimmune diseases in humans. This review examines possible causes for this paradox. This review delineates how the effects of estrogens are dependent on criteria such as: 1) the immune stimulus (foreign antigens or autoantigens) and subsequent antigen-specific immune responses (e.g., T cell inhibited by estrogens vs. activation of B cell); 2) the cell types involved during different phases of the disease; 3) the target organ with its specific microenvironment; 4) timing of 17beta-estradiol administration in relation to the disease course (and the reproductive status of a woman); 5) the concentration of estrogens; 6) the variability in expression of estrogen receptor alpha and beta depending on the microenvironment and the cell type; and 7) intracellular metabolism of estrogens leading to important biologically active metabolites with quite different anti- and proinflammatory function. Also mentioned are systemic supersystems such as the hypothalamic-pituitary-adrenal axis, the sensory nervous system, and the sympathetic nervous system and how they are influenced by estrogens. This review reinforces the concept that estrogens have antiinflammatory but also proinflammatory roles depending on above-mentioned criteria. It also explains that a uniform concept as to the action of estrogens cannot be found for all inflammatory diseases due to the enormous variable responses of immune and repair systems.

Aged rats lose vasoprotective and anti-inflammatory actions of estrogen in injured arteries

OBJECTIVE

17beta-estradiol (E2) negatively modulates neointima formation, leukocyte infiltration, and proinflammatory mediator expression after vascular injury in young (10-wk-old) ovariectomized (OVX) rats. Trials of E2 in elderly postmenopausal women have not confirmed a vasoprotective effect. This study tested the hypothesis that responsiveness to E2 is lost in injured arteries of aged (12-mo-old) OVX rats.

DESIGN

E2- or vehicle-treated OVX rats underwent balloon injury of the carotid artery and were killed after 2 weeks for morphometric examination of arteries, after 24 hours for assessment of leukocyte infiltration, and after 2 hours for quantification of proinflammatory mediator mRNA expression.

RESULTS

Neointima formation was significantly reduced in aged compared with young vehicle-treated rats. E2 treatment had directionally opposite effects on intima/media ratios in aged (+75%) and young (-40%) rats. Injury induced increases in infiltrating total leukocytes, neutrophils, monocytes/macrophages, and expression of proinflammatory mediators in arteries of aged rats; E2 had no effect on these inflammatory responses to injury. Estrogen receptor alpha and beta protein expression were similar in carotid arteries of young and aged rats on immunofluorescence testing.

CONCLUSIONS

Aged OVX rats lose the vasoprotective and anti-inflammatory responses to exogenous E2 seen in younger animals. These results may be relevant to the lack of vasoprotection observed in outcome trials of estrogen therapy in postmenopausal women.

Estrogen modulates TNF-α-induced inflammatory responses in rat aortic smooth muscle cells through estrogen receptor-β activation

We have previously shown that 17β-estradiol (E2) attenuates responses to endoluminal injury of the rat carotid artery, at least in part, by decreasing inflammatory mediator expression and neutrophil infiltration into the injured vessel, with a major effect on the neutrophil-specific chemokine cytokine-induced neutrophil chemoattractant (CINC)-2β. Current studies tested the hypothesis that activated rat aortic smooth muscle cells (RASMCs) express these same inflammatory mediators and induce neutrophil migration in vitro and that E2 inhibits these processes by an estrogen receptor (ER)-dependent mechanism. Quiescent RASMCs treated with E2, the ERα-selective agonist propyl pyrazole triol (PPT), the ERβ-selective agonist diarylpropiolnitrile (DPN), or vehicle for 24 h were stimulated with tumor necrosis factor (TNF)-α and processed for real-time RT-PCR, ELISA, or chemotaxis assays 6 h later. TNF-α stimulated and E2 attenuated mRNA expression of inflammatory mediators, including P-selectin, intercellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VCAM)-1, monocyte chemoattractant protein (MCP)-1, and CINC-2β. DPN dose dependently attenuated TNF-α-induced mRNA expression of CINC-2β, whereas PPT had no effect. The anti-inflammatory effects of DPN and E2 were blocked by the nonselective ER-inhibitor ICI-182,780. ELISA confirmed the TNF-α-induced increase and E2-induced inhibition of CINC-2β protein secretion. TNF-α treatment of RASMCs produced a twofold increase in neutrophil chemotactic activity of conditioned media; E2 and DPN treatment markedly inhibited this effect. E2 inhibits activated RASMC proinflammatory mediator expression and neutrophil chemotactic activity through an ERβ-dependent mechanism.

The effect of 17beta-estradiol on IL-6 secretion and NF-kappaB DNA-binding activity in human retinal pigment epithelial cells

Toll-like receptors (TLRs) and inflammatory cascades participate in the pathology of age-related macular degeneration (AMD). The effect of estrogens on the development of AMD is poorly understood, although many studies indicate that these compounds can modulate inflammatory responses. In this study, we investigated the regulatory role of TLR agonists and 17beta-estradiol (E(2)) on IL-6 expression and NF-kappaB DNA-binding activity in human retinal pigment epithelial cells (ARPE-19). The inflammatory response of ARPE-19 cells to various TLR agonists, e.g. Pam, zymosan, flagellin, SLTA and lipopolysaccharide (LPS) exposures were examined via the secretion of IL-6 cytokine as analyzed by ELISA. In addition, the IL-6 responses to the estrogen-receptor agonist, E(2), and to the estrogen-receptor antagonist ICI 182.780 as well as to the NF-kappaB inhibitor helenalin were compared. The DNA-binding activity of NF-kappaB transcription factor of nuclear cell extracts was analyzed by the gel mobility shift assay (EMSA). TLR4 gene expression was studied by quantitave PCR. The TLR4 agonist, LPS, caused a clear IL-6 response that was attenuated by E(2) in ARPE-19-cells. The anti-inflammatory properties of E(2) were mediated through estrogen receptors and were associated with decreased NF-kappaB DNA-binding activity. The level of TLR4 gene expression was not affected by LPS exposure. Our results indicate that IL-6 expression is regulated through NF-kappaB transcription factor and stereoid-receptor signalling pathways in ARPE-19 cells.

17beta-Estradiol inhibits keratinocyte-derived chemokine production following trauma-hemorrhage

Neutrophil infiltration is a key step in the development of organ dysfunction following trauma-hemorrhage (T-H). Although we have previously shown that 17beta-estradiol (E2) prevents neutrophil infiltration and organ damage following T-H, the mechanism by which E2 inhibits neutrophil transmigration remains unknown. We hypothesized that E2 prevents neutrophil infiltration via modulation of keratinocyte-derived chemokine (KC), a major attractant for neutrophils. To examine this, male C3H/HeN mice were subjected to T-H or sham operation and thereafter resuscitated with Ringer lactate and E2 (1 mg/kg body wt) or vehicle. Animals were killed 2 h after resuscitation, and Kupffer cells were isolated. Plasma levels and Kupffer cell production capacities of KC, TNF-alpha, and IL-6 were determined by BD Cytometric Bead Arrays; lung mRNA expression of KC was measured with real-time PCR; myeloperoxidase activity assays were performed to determine neutrophil infiltration, and organ damage was assessed by edema formation. Treatment with E2 decreased systemic levels and restored Kupffer cell production of KC, TNF-alpha, and IL-6, as well as KC gene expression and protein in the lung. This was accompanied with a decrease in neutrophil infiltration and edema formation in the lung. These results suggest that E2 prevents lung neutrophil infiltration and organ damage in part by decreasing KC during posttraumatic immune response.

Female gender attenuates cytokine and chemokine expression and leukocyte recruitment in experimental rodent abdominal aortic aneurysms

Female gender appears to be protective in the development of abdominal aortic aneurysms (AAAs). This study sought to identify gender differences in cytokine and chemokine expression in an experimental rodent AAA model. Male and female rodent aortas were perfused with either saline (control) or elastase to induce AAA formation. Aortic diameter was determined and aortic tissue was harvested on postperfusion days 4 and 7. Cytokine and chemokine gene expression was examined using focused gene arrays. Immunohistochemistry was used to quantify aortic leukocyte infiltration. Data were analyzed by Student's t-tests and ANOVA. Elastase-perfused female rodents developed significantly smaller aneurysms compared to males by day 7 (93 +/- 10% vs. 201 +/- 25%, P = 0.003). Elastase-perfused female aortas exhibited a fivefold decrease in expression of the BMP family and ligands of the TNF superfamily compared to males. In addition, the expression of members of the TGF beta and VEGF families were three to fourfold lower in female elastase-perfused aortas compared to males. Multiple members of the interleukin, CC chemokine receptor, and CC ligand families were detectable in only the male elastase-perfused aortas. Female elastase-perfused aortas demonstrated a corollary twofold lower neutrophil count (females: 17.5 +/- 1.1 PMN/HPF; males: 41 +/- 5.2 neutrophils/HPF, P = 0.01) and a 1.5-fold lower macrophage count (females: 12 +/- 1.1 macrophages/HPF; males: 17.5 +/- 1.1 macrophages/HPF, P = 0.003) compared to male elastase-perfused aortas. This study documents decreased expression of multiple cytokines and chemokines and diminished leukocyte trafficking in female rat aortas compared to male aortas following elastase perfusion. These genes may contribute to the gender disparity seen in AAA formation.

Selective Agonists of Estrogen Receptor Isoforms

The cloning of estrogen receptors (ERs) and generation of ER-deficient mice have increased our understanding of the molecular mechanisms underlying the cardiovascular effects of estrogen. It is conceivable that clinical trials of estrogens so far failed to improve cardiovascular health because of the poor ER isoform selectivity and tissue specificity of endogenous hormones as well as incorrect treatment timing and regimens. Tissue-selective ER modulators (SERMs) may be safer agents than endogenous estrogens for cardiovascular disease. Yet, designing isoform-selective ER ligands (I-SERMs) with agonist or antagonist activity is required to pursue improved pharmacological control of ERs, especially taking into account emerging evidence for the beneficial role of vascular ER alpha activation. Ideally, the quest for unique ER ligands targeted to the vascular wall should lead to compounds that merge the pharmacological profiles of SERM and I-SERM agents. This review highlights the current bases for and approaches to selective ER modulation in the cardiovascular system.

Soy-isoflavone-enriched foods and markers of lipid and glucose metabolism in postmenopausal women: interactions with genotype and equol production

BACKGROUND

The hypocholesterolemic effects of soy foods are well established, and it has been suggested that isoflavones are responsible for this effect. However, beneficial effects of isolated isoflavones on lipid biomarkers of cardiovascular disease risk have not yet been shown.

OBJECTIVE

The objective was to investigate the effects of isolated soy isoflavones on metabolic biomarkers of cardiovascular disease risk, including plasma total, HDL, and LDL cholesterol; triacylglycerols; lipoprotein(a); the percentage of small dense LDL; glucose; nonesterified fatty acids; insulin; and the homeostasis model assessment of insulin resistance. Differences with respect to single nucleotide polymorphisms in selected genes [ie, estrogen receptor alpha (XbaI and PvuII), estrogen receptor beta (AluI), and estrogen receptor beta(cx) (Tsp509I), endothelial nitric oxide synthase (Glu298Asp), apolipoprotein E (Apo E2, E3, and E4), cholesteryl ester transfer protein (TaqIB), and leptin receptor (Gln223Arg)] and with respect to equol production were investigated.

DESIGN

Healthy postmenopausal women (n = 117) participated in a randomized, double-blind, placebo-controlled, crossover dietary intervention trial. Isoflavone-enriched (genistein-to-daidzein ratio of 2:1; 50 mg/d) or placebo cereal bars were consumed for 8 wk, with a wash-out period of 8 wk before the crossover.

RESULTS

Isoflavones did not have a significant beneficial effect on plasma concentrations of lipids, glucose, or insulin. A significant difference between the responses of HDL cholesterol to isoflavones and to placebo was found with estrogen receptor beta(cx) Tsp509I genotype AA, but not GG or GA.

CONCLUSIONS

Isoflavone supplementation, when provided in the form and dose used in this study, had no effect on lipid or other metabolic biomarkers of cardiovascular disease risk in postmenopausal women but may increase HDL cholesterol in an estrogen receptor beta gene-polymorphic subgroup.

Tissue-specific expression of estrogen receptors and their role in the regulation of neutrophil infiltration in various organs following trauma-hemorrhage

Although 17beta-estradiol (E2) administration after trauma-hemorrhage (T-H) reduces tissue neutrophil sequestration in male rodents, it remains unknown which of the estrogen receptor (ER) subtypes mediates this effect and whether the same ER subtype is involved in all the tissues. We hypothesized that the salutary effects of E2 on attenuation of neutrophil accumulation following T-H are tissue and receptor subtype-specific. Male Sprague-Dawley rats underwent sham operation or T-H (mean blood pressure, 40 mmHg for 90 min and then resuscitation). E2 (50 microg/kg), ER-alpha agonist propyl pyrazole triol (PPT; 5 microg/kg), ER-beta agonist diarylpropiolnitrile (DPN; 5 microg/kg), or vehicle (10% dimethyl sulfoxide) was administered subcutaneously during resuscitation. Twenty-four hours thereafter, tissue myeloperoxidase (MPO) activity (a marker of neutrophil sequestration), cytokine-induced neutrophil chemoattractant (CINC)-1, CINC-3, and intercellular adhesion molecule (ICAM)-1 levels in the liver, intestine, and lung were measured (n = 6 rats/group). ER-alpha and ER-beta mRNA levels in sham-operated rats were also determined. T-H increased MPO activity, CINC-1, CINC-3, and ICAM-1 levels in the liver, intestine, and lung. These parameters were improved significantly in rats receiving E2 after T-H. Administration of the ER-alpha agonist PPT but not the ER-beta agonist DPN improved the measured parameters in the liver. In contrast, DPN but not PPT significantly improved these parameters in the lung. In the intestine, ER subtype specificity was not observed. ER-alpha mRNA expression was highest in the liver, whereas ER-beta mRNA expression was greatest in the lung. Thus, the salutary effects of E2 administration on tissue neutrophil sequestration following T-H are receptor subtype and tissue-specific.

A novel peptide CXCR ligand derived from extracellular matrix degradation during airway inflammation

We describe the tripeptide neutrophil chemoattractant N-acetyl Pro-Gly-Pro (PGP), derived from the breakdown of extracellular matrix (ECM), which shares sequence and structural homology with an important domain on alpha chemokines. PGP caused chemotaxis and production of superoxide through CXC receptors, and administration of peptide caused recruitment of neutrophils (PMNs) into lungs of control, but not CXCR2-deficient mice. PGP was generated in mouse lung after exposure to lipopolysaccharide, and in vivo and in vitro blockade of PGP with monoclonal antibody suppressed PMN responses as much as chemokine-specific monoclonal antibody. Extended PGP treatment caused alveolar enlargement and right ventricular hypertrophy in mice. PGP was detectable in substantial concentrations in a majority of bronchoalveolar lavage samples from individuals with chronic obstructive pulmonary disease, but not control individuals. Thus, PGP's activity links degradation of ECM with neutrophil recruitment in airway inflammation, and PGP may be a biomarker and therapeutic target for neutrophilic inflammatory diseases.

Deficiencies in estrogen-mediated regulation of cerebrovascular homeostasis may contribute to an increased risk of cerebral aneurysm pathogenesis and rupture in menopausal and postmenopausal women

Despite the catastrophic consequence of ruptured intracranial aneurysms, very little is understood regarding their pathogenesis, and there are no reliable predictive markers for identifying at-risk individuals. Few studies have addressed the molecular pathological basis and mechanisms of intracranial aneurysm formation, growth, and rupture. The pathogenesis and rupture of cerebral aneurysms have been associated with inflammatory processes, and these have been implicated in the digestion and breakdown of vascular wall matrix. Epidemiological data indicate that the risk of cerebral aneurysm pathogenesis and rupture in women rises during and after menopause as compared to premenopausal women, and has been attributed to hormonal factors. Moreover, experimental evidence supports a role for estrogen in the modulation of each phase of the inflammatory response implicated in cerebral aneurysm pathogenesis and rupture. While the risk of aneurysm rupture in men also increases with age, this increased risk has been attributed to other recognized risk factors including cigarette smoking, use of alcohol, and history of hypertension, all of which are more common in men than women. We hypothesize, therefore, that decreases in both circulating estrogen levels and cerebrovascular estrogen receptor density may contribute to an increased risk of cerebral aneurysm pathogenesis and rupture in women during and after menopause. To test our hypothesis, experiments are needed to identify genes regulated by estrogen and to evaluate gene expression and intracellular mechanisms in cells/tissues exposed to varying concentrations and duration of treatment with estrogen, metabolites of estrogen, and selective estrogen receptor modulators (SERMs). Furthermore, it is not likely that the regulation of cerebrovascular homeostasis is due to the actions of estrogen alone, but rather the interplay of estrogen and other hormones and their associated receptor expression. The potential interactions of these hormones in the maintenance of normal cerebrovascular tone need to be elucidated. Additional studies are needed to define the role that estrogen and other sex hormones may play in the cerebrovascular circulation and the pathogenesis and rupture of cerebral aneurysms. Efforts directed at understanding the basic pathophysiological mechanisms of aneurysm pathogenesis and rupture promise to yield dividends that may have important therapeutic and clinical implications. The development of non-invasive tools such as molecular MRI for the detection of specific cells, molecular markers, and tissues may facilitate early diagnosis of initial pathophysiological changes that are undetectable by clinical examination or other diagnostic tools, and can also be used to evaluate the state of activity of cerebral aneurysm pathogenesis before, during, and after treatment.

17beta-estradiol potentiates ischemia-reperfusion injury in diabetic ovariectomized female rats

To investigate the effect of 17beta-estradiol (E2) on ischemia-reperfusion (I/R) injury in diabetic ovariectomized female rats. Streptozotocin(STZ)-induced diabetic female rats received E2 treatment for 2 weeks after ovariectomy (OVX). A period of 90 min of temporary middle cerebral artery occlusion (tMCAO) was used for the study. Rats were evaluated for physiological data including plasma glucose, E2, MAP, PaCO2 and PaO2 before and after tMCAO. P-selectin expression, myeloperoxidase (MPO) enzyme activity and the cerebral infarct volume were analyzed.

RESULTS

The infarct volume in the E2-treated OVX rats is bigger than that in intact and OVX groups. However, there is not a significant different area of cerebral infarct between diabetic OVX and intact rats. Significant upregulation of P-selectin expression and MPO activity of the ischemia-reperfusion hemisphere were observed in E2 + OVX, intact and OVX groups at 8, 24, 72 h in time manner after tMCAO compared with that of the contralateral hemisphere of cerebral ischemia-reperfusion. Both P-selectin expression and MPO activity in the E2 + OVX and intact rats are significantly higher than that in the untreated OVX rats. Chronic estrogen replacement therapy (ERT) potentiates the I/R injury in diabetes female rats. This may be related to the increased expression of P-selectin and MPO activity.

Altered CXCR2 signaling in beta-arrestin-2-deficient mouse models

CXCR2 is a G-protein-coupled receptor (GPCR) that binds the CXC chemokines, CXCL1-3 and CXCL5-8, and induces intracellular signals associated with chemotaxis. Many adaptor proteins are actively involved in the sequestration, internalization, and trafficking of CXCR2 and transduction of agonist-induced intracellular signaling. We have previously shown that adaptor protein beta-arrestin-2 (betaarr2) plays a crucial role in transducing signals mediated through CXCR2. To further investigate the role of betaarr2 on CXCR2-mediated signaling during acute inflammation, zymosan-induced neutrophils were isolated from peritoneal cavities of betaarr2-deficient (betaarr2(-/-)) and their wild-type (betaarr2(+/+)) littermate mice, and neutrophil CXCR2 signaling activities were determined by measurement of Ca(2+) mobilization, receptor internalization, GTPase activity, and superoxide anion production. The results showed that the deletion of betaarr2 resulted in increased Ca(2+) mobilization, superoxide anion production, and GTPase activity in neutrophils, but decreased receptor internalization relative to wild-type mice. Two animal models, the dorsal air pouch model and the excisional wound healing model, were used to further study the in vivo effects of betaarr2 on CXCR2-mediated neutrophil chemotaxis and on cutaneous wound healing. Surprisingly, the recruitment of neutrophils was increased in response to CXCL1 in the air pouch model and in the excisional wound beds of betaarr2(-/-) mice. Wound re-epithelialization was also significantly faster in betaarr2(-/-) mice than in betaarr2(+/+) mice. Taken together, the data indicate that betaarr2 is a negative regulator for CXCR2 in vivo signaling.

Estrogen Treatment Abrogates Neointima Formation in Human C-Reactive Protein Transgenic Mice

Objective— Previously we established that the vascular injury response was attenuated in ovariectomized wild-type rodents treated with 17β-estradiol (E 2 ). We also showed that the response to acute vascular injury in transgenic mice expressing human C-reactive protein (CRPtg) is exaggerated compared with their nontransgenic (NTG) counterparts. Herein we tested the hypothesis that E 2 modulates vascular injury in the CRPtg mouse.

Methods and Results— Intact (INT) or ovariectomized (OVX) CRPtg and NTG, treated with E 2 or vehicle, had their right common carotid artery ligated. Resultant neointima formation was exaggerated in CRPtg compared with NTG, whether INT or OVX, but was prevented in both genotypes by E 2 . Expression of human CRP protein (immunohistochemical analysis) and mRNA (laser microdissection followed by real-time quantitative RT-PCR) was detected in the neointima of OVX CRPtg and was greatly diminished by E 2 treatment. CRP was not detected in uninjured arteries or in the media of injured arteries, and blood CRP level was consistently low.

Conclusions— The exaggerated response to vascular injury in CRPtg is associated with increased neointimal expression of human CRP. E 2 reduces both neointima formation and neointimal expression of human CRP, suggesting that E 2 is vasoprotective.