Natural killer cells express estrogen receptor-alpha and estrogen receptor-beta and can respond to estrogen via a non-estrogen receptor-alpha-mediated pathway

Surgery as a double-edged sword: a clinically feasible approach to overcome the metastasis-promoting effects of surgery by blunting stress and prostaglandin responses

Surgery remains an essential therapeutic approach for most solid malignancies, including breast cancer. However, surgery also constitutes a risk factor for promotion of pre-existing micrometastases and the initiation of new metastases through several mechanisms, including the release of prostaglandins and stress hormones (e.g., catecholamines and glucocorticoids). However, the perioperative period also presents an opportunity for cell mediated immunity (CMI) and other mechanisms to eradicate or control minimal residual disease, provided that the deleterious effects of surgery are minimized. Here, we discuss the key role of endogenous stress hormones and prostaglandins in promoting the metastatic process through their direct impact on malignant cells, and through their deleterious impact on anti-cancer CMI. We further discuss the effects of anesthetic techniques, the extent of surgery, pain alleviation, and timing within the menstrual cycle with respect to their impact on tumor recurrence and physiological stress responses. Last, we suggest an attractive perioperative drug regimen, based on a combination of a cyclooxygenase (COX)-2 inhibitor and a β-adrenergic blocker, which we found effective in attenuating immune suppression and the metastasis-promoting effects of surgery in several tumor models. This regimen is clinically applicable, and could potentially promote disease free survival in patients operated for breast and other types of cancer.

Sex steroids as inflammatory regulators

It is becoming increasingly clear that endogenous sex steroids are key players in a range of inflammatory contexts. Androgens and estrogens have been shown to have a profound influence on the function of inflammatory cells including macrophages and on the secretion and activation of a range of plasma-borne inflammatory mediators. The menopause and polymorphisms in estrogen receptor genes have separately been shown to affect the incidence of a range of inflammatory disorders. Sex steroids themselves have been shown to be protective in certain conditions; harmful in others. This review will summarize their documented effects on inflammatory processes, with particular focus on two areas that have received much recent attention: the antiatherosclerotic properties of estrogens in females and the wound healing effects of sex steroids.

Estrogen augments the T cell-dependent but not the T-independent immune response

Estrogen plays a critical regulatory role in the development and maintenance of immunity. Its role in the regulation of antibody synthesis in vivo is still not completely clear. Here, we have compared the effect of estrogen on T cell-dependent (TD) and T cell-independent type 2 (TI-2) antibody responses. The results provide the first evidence that estrogen enhances the TD but not the TI-2 response. Ovariectomy significantly decreased, while estrogen re-administration increased the number of hapten-specific IgM- and IgG-producing cells in response to TD antigen. In vitro experiments also show that estrogen may have a direct impact on B and T cells by inducing rapid signaling events, such as Erk and AKT phosphorylation, cell-specific Ca(2+) signal, and NFkappaB activation. These non-transcriptional effects are mediated by classical estrogen receptors and partly by an as yet unidentified plasma membrane estrogen receptor. Such receptor- mediated rapid signals may modulate the in vivo T cell-dependent immune response.

Genetic and hormonal factors in female-biased autoimmunity

Autoimmunity is controlled both by the environment and by genetic factors. One of the most well defined genetic factors is polymorphisms, with some alleles of particular genes promoting autoimmune diseases, whereas other alleles either not affecting susceptibility to disease or, in some cases actually inhibiting the appearance of such illnesses. Another genetically controlled factor, gender, also plays a profound role in the incidence of autoimmune diseases. For example, Systemic Lupus Erythematosus (SLE) occurs much more frequently in females than in males in both mice and man. The genetic differences that make some individuals susceptible to autoimmunity and protect others could act in many ways and affect many tissues. In this review we will discuss how gender may act on the cells of the immune system and thereby influence the predisposition of the host to autoimmune diseases.

Geoepidemiology of COPD and idiopathic pulmonary fibrosis

Progress in improving patient outcomes and advancing therapeutics in chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF) is hampered by phenotypic heterogeneity and variable responsiveness to clinical interventions that are not fully explained by currently held disease paradigms for COPD and IPF. Although these chronic lung diseases differ in their geoepidemiology and immunopathogenesis, emerging evidence suggest that organ-specific autoimmunity may underlie subphenotypes of COPD and IPF. In particular, the links to tobacco smoking, diet, gender, and environment are explored in this review. We also highlight potential mechanisms that could guide future investigations in both laboratory and clinical settings. A paradigm shift is needed in how we think about COPD and IPF, based on geoepidemiology and a broader understanding of disease pathogenesis that may ultimately lead to new therapies and improved patient outcomes.

Estrogen receptor-alpha and -beta and aromatase knockout effects on lower limb muscle mass and contractile function in female mice

Estrogen (E2) is reported to regulate skeletal muscle mass and contractile function; whether E2 exerts its effects through estrogen receptor-alpha (ERalpha) or -beta (ERbeta) is unclear. We determined the effect of ERalpha or ERbeta elimination on muscle mass and contractile function in multiple muscles of the lower limb, muscles with different locomotor tasks and proportions of fiber types I and II: soleus (Sol), plantaris (Plan), tibialis anterior (TA), and gastrocnemius (Gast) in mature female mice. To determine E2 elimination effects on muscle, we also used aromatase (Ar) knockout (KO) and wild-type (WT) mice. ERalpha and ArKO body weights were approximately 10 and 20% higher than WT. Although muscle mass tended to show a commensurate increase in both groups, only the TA was significantly larger in ERalpha (P<0.05). Ratios of muscle mass to body mass revealed significantly lower values for Gast and TA in ArKO mice (P<0.05). Tetanic tension (Po) per calculated anatomical cross-sectional area (aCSA) in ERalpha KO was lower in TA and Gast than in WT. Lower Po/aCSA in ERalpha KO Gast and TA was also supported histologically by significantly less Po/fiber areas (P<0.05). ArKO mice also had lower Po/aCSA in Gast and TA compared with WT. ERbeta KO and WT mice were comparable in all measures. Our results support the hypothesis that E2 effects on skeletal muscle are mediated in part via the ERalpha but that E2 effects may be mediated via more than one mechanism or receptor.

Gender and sex hormones in multiple sclerosis pathology and therapy

Several lines of evidence indicate that gender affects the susceptibility and course of multiple sclerosis (MS) with a higher disease prevalence and overall better prognosis in women than men. This sex dimorphism may be explained by sex chromosome effects and effects of sex steroid hormones on the immune system, blood brain barrier or parenchymal central nervous system (CNS) cells. The well known improvement in disease during late pregnancy has also been linked to hormonal changes and has stimulated recent clinical studies to determine the efficacy of and tolerance to sex steroid therapeutic approaches. Both clinical and experimental studies indicate that sex steroid supplementation may be beneficial for MS. This could be related to anti-inflammatory actions on the immune system or CNS and to direct neuroprotective properties. Here, clinical and experimental data are reviewed with respect to the effects of sex hormones or gender in the pathology or therapy of MS or its rodent disease models. The different cellular targets as well as some molecular mechanisms likely involved are discussed.

17beta-estradiol alters the activity of conventional and IFN-producing killer dendritic cells

Estrogens increase aspects of innate immunity and contribute to sex differences in the prevalence of autoimmune diseases and in response to infection. The goal of the present study was to assess whether exposure to 17beta-estradiol (E2) affects the development and function of bone marrow-derived dendritic cells and to determine whether similar changes are observed in CD11c(+) splenocytes exposed to E2 in vivo. E2 facilitated the differentiation of BM precursor cells into functional CD11c(+)CD11b(+)MHC class II(+) dendritic cells (DCs) with increased expression of the costimulatory molecules CD40 and CD86. Exposure of bone marrow-derived dendritic cells to E2 also enhanced production of IL-12 in response to the TLR ligands, CpG and LPS. In contrast, CD11c(+) cells isolated from the spleens of female C57BL/6 mice that were intact, ovariectomized, or ovariectomized with E2 replacement exhibited no differences in the number or activity of CD11c(+)CD11b(+)MHC class II(+) DCs. The presence of E2 in vivo, however, increased the number of CD11c(+)CD49b(+)NK1.1(low) cells and reduced numbers of CD11c(+)CD49b(+)NK1.1(high) cells, a surface phenotype for IFN-producing killer DCs (IKDCs). Ultrastructural analysis demonstrated that CD11c(+)NK1.1(+) populations were comprised of cells that had the appearance of both DCs and IKDCs. CD11c(+) splenocytes isolated from animals with supplemental E2 produced more IFN-gamma in response to IL-12 and IL-18. These data illustrate that E2 has differential effects on the development and function of DCs and IKDCs and provide evidence that E2 may strengthen innate immunity by enhancing IFN-gamma production by CD11c(+) cells.

Modulation of 17beta-estradiol on the number and cytotoxicity of NK cells in vivo related to MCM and activating receptors

Natural killer (NK) cells are key components of immune systems and their activities could be regulated by sex hormones. In the present study we investigate the effects of estrogen on the number and cytotoxic activity of NK cells in vivo. The number and cytotoxicity of NK cells in four groups (control, sham+vehicle, Ovx+vehicle and Ovx+E2) were determined. The results showed that 17beta-estradiol (E2) increased the number of NK cells, but reduced their cytotoxicity. The increase of NK cells proportions by E2 may be mediated by up-regulating the expression of MCM7 and MCM10 proteins, which are required for DNA replication licensing in cell proliferation. The suppressed cytotoxicity of splenic NK cells by E2 may be attributable to the down-regulation of NK cells activating receptors-CD69, NKp46, NKG2DL and 2B4 (CD244), which directly inhibited NK cell activation, resulting in the reduced secretion of the soluble factors-granzyme B and FasL. INF-gamma might also act as a negative regulator in the low cytotoxicity of NK cells. In addition, the number of the NK cells is not parallel to their cytotoxicity with a long-term exposure to E2 in vivo. These results suggest that E2-mediated low cytotoxicity of NK cells may regulate host immune response in pregnancy and some female predominant diseases.

Estrogenic regulation of host immunity against an estrogen receptor-negative human breast cancer

PURPOSE

The risk of developing breast cancer is positively correlated with exposure to increased levels of estrogen and/or an increased duration of estrogen exposure. Many different mechanisms have been proposed to explain the association of estrogens with breast cancer risk; however, the well-documented immune modulatory properties of estrogen have received little attention. In part, this is due to a lack of suitable models for studying this relationship.

EXPERIMENTAL DESIGN

We have developed an animal model using estrogen receptor (ER)-negative human breast cancer cell line, MDA-MB-468, xenografted into severe combined immunodeficient (SCID) mice. We also generated the ER-alpha knockout (ER-alphaKO) mice on the SCID background and then tested the ability of 17beta-estradiol to stimulate growth of xenografted ER-negative human breast cancer tumors in wild-type and ER-alphaKO SCID mice. We quantified vascularization of tumors, macrophage recruitment to the tumor site by immunocytochemistry, and inflammatory cytokine production.

RESULTS

We show that estrogen treatment of C57BL/6/SCID mice promotes the growth of xenografted ER-negative tumors in wild-type mice and this estrogen-induced tumor growth is abrogated in ER-alphaKO mice. Tumor neovascularization of estrogen-treated mice was unchanged versus control; however, estrogen treatment of the C57BL/6/SCID host suppressed macrophage recruitment to and inflammatory cytokine production at the tumor site.

CONCLUSIONS

These data are consistent with estrogen modulation of the inflammatory response as a contributing factor in estrogen-stimulated growth of an ER-negative tumor. This effect on the host innate immune response was mediated by ER-alpha.

Why do some breast cancer cells remain dormant?

Dormant breast cancer cells are a reality that cannot be overlooked. They may stay dormant either after a spread of cancer cells caused by surgery or after being generated by spontaneous or induced mutations in the course of breast gland growth. Some cases are presented in support of both possibilities, followed by a critical appraisal of the factors that may either keep them dormant or later stimulate their growth into a breast cancer.

Effects of 17β-estradiol on the maturation, nuclear factor kappa B p65 and functions of murine spleen CD11c-positive dendritic cells

Physiological gender differences in immune capabilities are now well recognized and suggest that sex steroid hormones such as estrogens may be involved in the regulation of the immunocompetence. In this paper, CD11c-positive murine spleen dendritic cells (SDCs) were treated with various concentrations of 17beta-estradiol (E2) for 24h. The viability, phenotype, nuclear factor kappa B p65 (NF-kappaBp65), endocytosis, stimulatory capacity and cytokine expression were analyzed. Our results showed that E2 increased the viability and MHC-II expression but decreased nuclear NF-kappaBp65 level and endocytosis of SDCs. E2 also increased the stimulatory capacity of SDCs from low-dose group but decreased it from middle- and high-dose ones. In addition, E2 increased the intracellular expression of IL-6 and IL-10 in SDCs, but no obvious change appeared in IL-12 and TNF-alpha. These data suggested that E2 might influence the immune responses by changing the viability, maturation, NF-kappaBp65, endocytosis, stimulatory capacity and cytokine expression of SDCs.

Sex hormones and SLE: influencing the fate of autoreactive B cells

The prevalence of systemic lupus erythematosus (SLE) is far higher in females than in males and numerous investigations to understand this gender bias have been conducted. While it is plausible that some sex-linked genes may contribute to the genetic predisposition for the disease, other likely culprits are the sex hormones estrogen and prolactin. In this chapter we review studies that have addressed the influence of sex hormones in SLE activity and discuss the recent data established in a BALB/c mouse transgenic for the heavy chain of an anti-DNA antibody. These mice are prone to develop lupus following exposure to exogenous sex hormones. We describe how estrogen and prolactin influence B cell maturation and selection, permitting B cells to mature to immunocompetence. Finally, we discuss the relevance and implications of these data for human disease.

Future Perspectives in the Medical Treatment of Endometriosis

In the last few years, our understanding of the pathogenesis of endometriosis at the cellular and molecular levels has improved significantly. This may give us the opportunity to use new, specific agents for the treatment of this disorder. Despite the effectiveness of the available treatments, novel therapeutic strategies may improve our ability to eliminate endometriotic lesions when present and to prevent the recurrence of endometriosis after surgical treatment. This review focuses on the new, experimental approaches to the medical treatment of endometriosis and its symptoms. The blockage of aromatase activity in endometriotic lesions with an aromatase inhibitor may represent a new step in the medical treatment of endometriosis. Preliminary clinical studies have demonstrated the efficacy of third-generation nonsteroidal aromatase inhibitors (ie, anastrozole and letrozole) in reducing the intensity of pain symptoms associated with the presence of endometriosis. The new selective progesterone receptor modulators may represent a valid hormonal treatment option. Therapeutic manipulation of the immune system through TNFalpha inhibitors may be beneficial in women with endometriosis. New pharmaceutical agents affecting inflammation, angiogenesis, and matrix metalloproteinase activity may prevent or inhibit the development of endometriosis. Further clinical trials may determine if these new therapies are superior to current medical treatment strategies for endometriosis.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians Learning.

OBJECTIVES

After completion of this article, the reader should be able to describe the new experimental medical treatments of endometriosis, state that the clinical use of nonsteroidal aromatase inhibitors for endometriosis appears to be efficacious but is based on preliminary clinical data, and recall that the drugs used for endometriosis in the future may include manipulation of the immune system.

Estrogen receptor alpha (ERalpha) deficiency in macrophages results in increased stimulation of CD4+ T cells while 17beta-estradiol acts through ERalpha to increase IL-4 and GATA-3 expression in CD4+ T cells independent of antigen presentation

The effects of 17beta-estradiol (E2) on immune function have been extensively reported. The effects are dependent on concentration and duration of exposure and potential differences in signaling between the known E2 receptors, estrogen receptors (ER) alpha and ERbeta. Through the use of ER-deficient mice, we and others have begun to demonstrate the role of the two known receptors in modulating immune functional activities. Previous studies have shown that cells of the innate immune system have altered function (bactericidal capacity) and patterns of cytokine expression (increased proinflammatory cytokine expression) through amelioration of ERalpha signaling. In this study, we extend these studies to analysis of T cell differentiation and proliferation in APC-dependent and APC-independent in vitro assay systems. Our results demonstrate that ERalpha deficiency in splenic macrophages, but not CD11c+ splenic dendritic cells pulsed with OVA significantly enhances proliferative responses and IFN-gamma production by transgenic OVA peptide-specific (OT-II) CD4+ T cells when compared with Ag-pulsed APC from wild-type littermates. The addition of E2 in this culture system did not significantly affect the production of IFN-gamma. In addition, when purified CD4+ T cells from ERalpha-deficient and wild-type littermates were stimulated with anti-CD3/CD28 Ab in the absence of E2, there were no significant differences in IFN-gamma or IL-4 production. However, the addition of E2 significantly increased IL-4 secretion, as well as increased GATA-3 mRNA levels from ERalpha-replete CD4+ T cells, while this effect was abrogated in ERalpha-deficient CD4+ T cells.

Effect of estrogen/progesterone hormone replacement therapy on natural killer cell cytotoxicity and immunoregulatory cytokine release by peripheral blood mononuclear cells of postmenopausal women

Sex steroids are known to affect immune responses; however, information on immunomodulatory effects of estrogen/progesterone hormone replacement therapy (HRT) is still limited. Therefore, the present study aimed to investigate the effect of estrogen/medroxyprogesterone HRT on natural killer (NK) cell cytotoxicity and immunoregulatory cytokine (IL-2, IL-4 and IFN-gamma) release by phytohemaglutinin (PHA)-stimulated peripheral blood mononuclear cells (PBMC) from 15 selected healthy postmenopausal women. NK cell cytotoxicity, cytokine production and serum levels of 17beta-estradiol (E2), progesterone (P) and FSH were tested in each patient before and after 90-days HRT. NK cell cytotoxicity was tested by (51)Cr-release assay using K562 erythroleukemic cells as target. Specific cytokine production and serum hormone levels were evaluated by enzyme-linked immunosorbent assay (ELISA) and immunochemiluminescent assays, respectively. HRT resulted in a significant decrease of Kupperman index, an increase of E2 and a decrease of FSH levels. These changes were associated with a significant decrease of NK cell cytotoxicity, IL-2 and IFN-gamma production. The levels of IL-4 production remained unchanged. Changes of NK cell cytotoxicity and cytokine release in individual patients did not correlate with changes of serum sex hormone levels. Nevertheless, the present results imply strongly that estrogen/progesterone HRT may affect cell-mediated immunity, thus being a potential factor influencing development and course of autoimmune disorders and neoplastic diseases.

Stimulation of the immune response in B6C3F1 mice by genistein is affected by exposure duration, gender, and litter order

The objective of this study was to determine whether immune responses could be differentially modulated by the phytoestrogen genistein (GEN) in mice from the 1st and 2nd litters, and whether the effects were persistent or reversible. B6C3F1 mice were exposed to a control or GEN-containing diet at 25, 250, and 1250 microg/g for the 1st litters, and 500 microg/g for the 2nd litters from d 0 of gestation to postnatal day (PND) 22, and through feeding after weaning. At PND42, anti-CD3 antibody-stimulated splenic T-cell proliferation and the percentages of T cells were increased in mice from the 1st litters at 250 and 1250 microg/g GEN but not from the 2nd litters. At PND84, the activity of IL-2-treated NK cells was significantly increased by GEN in mice from the 2nd litters but not from the 1st litters. The activity of cytotoxic T cells (CTLs) was also significantly increased by GEN in male mice from the 2nd litters. However, the increases in the CTL activity were not significant when the male mice were shifted from GEN-containing food to control food at PND22. Additionally, the increases in T-cell activities in female mice from the 1st litters and male mice from the 2nd litters were associated with a decrease in the percentage of CD4+CD25+ T regulatory cells. Overall, the results demonstrated that GEN could enhance the immune responses in mice from the 1st and 2nd litters; however, the effects varied depending on the exposure duration, gender, and litter order.

Sex-specific effects of neonatal exposures to low levels of cadmium through maternal milk on development and immune functions of juvenile and adult rats

Cadmium (Cd) is a major environmental contaminant. Although immunotoxic effects have been associated with Cd exposure, the inconsistency of experimental results underlines the need of an experimental approach more closely related to environmental conditions. We investigated the effects of exposing neonatal Sprague-Dawley rats to environmentally relevant doses of Cd through maternal milk. Dams received 10 parts per billion (ppb) or 5 parts per million (ppm) Cd chloride (CdCl2) in drinking water from parturition until the weaning of the pups. Half of the offspring was sampled at weaning time. The remaining juvenile rats received water without addition of Cd until adulthood. Cd accumulation in kidneys of juvenile rats fed from dams exposed to Cd indicated the transfer of the metal from mother to pups through maternal milk. This neonatal exposure resulted in decreased body, kidney and spleen weights of just weaned females but not of males. This effect was more pronounced in the less exposed females fed from dams exposed to 10 ppb Cd, which also displayed lower hepatic metallothionein-1 (MT-1) mRNA levels. The effect of Cd exposure on body and organ weights did not persist to adulthood. In contrast, we observed gender-specific effects of neonatal Cd exposure on the cytotoxic activity of splenic NK-cells of both juvenile and adult rats. Cd also strongly inhibited the proliferative response of Con A-stimulated thymocytes in both male and female adult rats 5 weeks after the cessation of Cd exposure. These immunotoxic effects were observed at doses much lower than those reported to produce similar effects when exposure occurred during adulthood. In conclusion, neonatal exposures to environmentally relevant levels of Cd through maternal milk represent a critical hazard liable to lead to both transitory and persistent immunotoxic effects.

Menstrual cycle hormones induce changes in functional interactions between lymphocytes and decidual vascular endothelial cells

During the secretory phase of the menstrual cycle, a natural killer (NK) cell subset expressing cluster of differentiation (CD)56bright appears in the decidualizing uterus and remains until onset of menses. If pregnancy occurs, decidual NK cells increase to become the predominant uterine lymphocytes of early pregnancy. To elucidate mechanisms of CD56bright cell recruitment to the uterus, an in vitro adhesion assay was used to assess the effect of the menstrual cycle, as well as cycle-associated hormones on adhesive properties of human lymphocytes. Adhesion of human peripheral blood lymphocytes to pregnant mouse lymph nodes and Peyer's Patches tissue sections was constant throughout the cycle. When uterine tissue was used as the substrate, adhesive CD56+ cells were found only in decidua basalis. Adhesion increased at the LH surge. Adhesion was mediated through both L-selectin and alpha4-integrin-dependent mechanisms. Furthermore, we observed increased adhesive function in CD56+ cells from male donors which had been cultured with estradiol or LH compared with cell aliquots cultured without additives. Lymphocytes adherent to mouse uterine tissue were predominantly CD56bright, suggesting that peripheral NK cells may be actively recruited to the uterus in an important, brief endocrine-regulated fashion at the time of ovulation to establish the decidual NK population of early pregnancy.

IgM production of lymphocytes from C57BL/6N mice was stimulated by estrogen treated splenic adherent cells

Estrogens have diverse effects on cell growth, differentiation and homeostatic functions, and have been shown to play an important role in regulating immune system. In this study, we examined the effect of 17beta-estradiol (E2) on antibody production by splenocytes isolated from C57BL/6N mice. Our results suggest that the activation of immunoglobulin (Ig) M production by E2 requires direct cell-cell interaction between adherent and non-adherent cells in mouse splenocyte population, and the primary target of E2 is adherent cell population. In addition, we indicated that ER antagonist ICI 182780 suppressed this enhancing effect of E2. Both ERalpha agonist and ERalpha agonist enhanced IgM production of mouse splenocytes. ERs are expressed on plasma membrane as well as in nucleus. However, a plasma membrane-associated ER specific ligand has no stimulation effect on IgM production. In conclusion, our results indicate that adherent cells stimulated by E2 up-regulate IgM production of lymphocytes through the direct cell-cell interactions, and the enhancing effect of E2 is arouse through ERalpha and ERbeta on these cells.

Sex hormones and the immune response in humans

In addition to their effects on sexual differentiation and reproduction, sex hormones appear to influence the immune system. This results in a sexual dimorphism in the immune response in humans: for instance, females produce more vigorous cellular and more vigorous humoral immune reactions, are more resistant to certain infections, and suffer a higher incidence of autoimmune diseases. Disease expression is also affected by the reproductive status of the female. As sex steroids--estrogens, progesterone and testosterone--differ between gender and within different reproductive stages, a lot of research has focussed on the effects of sex hormones on immune responses. Although there is also a vast literature on the effects of sex hormones on immune responses in animals, in this review we will focus on the most intriguing effects and mechanisms by which sex hormones affect different components of the immune system in humans.

A selective estrogen receptor-β agonist causes lesion regression in an experimentally induced model of endometriosis

BACKGROUND

Endometriosis is a common gynaecological problem of uncertain aetiology. It affects primarily young, reproductive-aged women and can result in chronic pelvic pain and infertility. Current approved therapies have significant side-effects and hysterectomy is employed as a final solution. ERB-041 is a selective estrogen receptor-beta (ERbeta) agonist that has anti-inflammatory activity in preclinical models of arthritis and inflammatory bowel disease, but is inactive in many preclinical models of classic estrogen activity. Because endometriosis is now thought to be, at least in part, an inflammatory disease, we evaluated ERB-041's activity in an experimentally induced model of endometriosis.

METHODS

Athymic nude mice (ovariectomized or intact) were implanted with tissue fragments of normal human endometrium. After establishment of lesions for 11-14 days, mice were treated with ERB-041 for 15-17 days. Upon euthanasia, the number of lesions, their size and location were noted. Five lesions were recovered for RNA analysis.

RESULTS

Across six studies, ERB-041 caused complete lesion regression in 40-75% of the mice studied. The compound appeared to be equally effective in gonad-intact as in ovariectomized mice, and analysed recovered lesions expressed ERalpha but not ERbeta mRNA.

CONCLUSIONS

ERB-041 and possibly other ERbeta selective agonists may be a useful new approach to treating endometriosis.

Estrogen's effects on central and circulating immune cells vary with reproductive age

Previous work from this lab has shown that estrogen attenuates inflammatory cytokine production following brain lesions in young adult female rats, but not in older, reproductive senescent females. The present study was designed to elucidate whether these effects result from estrogen's actions on brain-resident immune cells (microglia) or on circulating immune cells recruited to the brain from blood. Microglia, harvested from the olfactory bulbs of ovariectomized young adult and reproductive senescent animals, were pretreated with 17beta-estradiol and subsequently with the bacterial endotoxin LPS. LPS treatment significantly increased the pro-inflammatory cytokine IL-1beta in microglial cultures harvested from young and senescent females, but estrogen treatment had no effect on cytokine expression in either group. In young adult-derived microglia, LPS treatment also increased nitric oxide (NO), which was attenuated by estrogen, and MMP-9, which was not affected by estrogen. Reproductive senescent-derived microglia cultures had higher basal expression of NO and MMP-9 activity as compared to those from young adult microglial cultures, although LPS did not further stimulate these inflammatory markers. In blood cultures, LPS stimulated a dose-dependent increase in the inflammatory cytokine TNF-alpha expression in both young adult and reproductive senescent animals. Estrogen replacement significantly attenuated TNF-alpha induction by LPS in blood cultures derived from young adult females. Paradoxically, estrogen replacement increased LPS-induced TNF-alpha expression in blood cultures derived from reproductive senescent animals as compared to age-matched controls. The age and estrogen dependent effects on circulating immune cells found in whole blood cultures closely mimic the effects of estrogen on cytokine expression in the young and senescent animals that we reported in vivo, supporting the hypothesis that the immunosuppressive actions of estrogen replacement on neural injury may result from hormone-action on circulating immune cells.

Natural killer cells in pregnancy and recurrent pregnancy loss: endocrine and immunologic perspectives

The endocrine system and the immune system interact closely during implantation and maintenance of pregnancy. One of the most striking examples of this communication is at the level of the decidua (endometrium of pregnancy). Here, under the influence of sex steroids, there is a dramatic increase of a unique population of lymphocytes, the uterine natural killer (uNK) cells, in early pregnancy. These cells derive predominantly from a subset of peripheral blood NK cells, which under hormonal influence gets recruited to the uterus. In mice, uNK cells play an important role in the development of placental vasculature. The role of these cells in human pregnancy is still not definitively established; however, they are believed to promote placental and trophoblast growth and provide immunomodulation at the maternal-fetal interface. In contrast to their presumptive role in the maintenance of a healthy pregnancy, uNK cells and peripheral NK cells are dysregulated in unexplained recurrent pregnancy loss. Herein, we review NK cell populations, their changes in number and function in altered endocrine environments during the menstrual cycle and pregnancy, the current data on their potential role in unexplained recurrent pregnancy loss, and mechanisms for potential therapies targeted to NK cell function for this enigmatic disorder.

Estrogen receptor beta and breast cancer

A second estrogen receptor, estrogen receptor-beta, was identified in 1996 and has led to an intensive re-evaluation of the role of estrogens in normal physiological and disease processes. While much has been learnt about this new receptor, there remain many outstanding questions, particularly regarding its prognostic significance and therapeutic implications.

Estrogen as an immunomodulator

Estrogen's role in the sex differences observed in autoimmune diseases such as systemic lupus, multiple sclerosis, and rheumatoid arthritis have remained unclear. Complicating the understanding of the immunomodulatory effects of estrogen are (1) the effects of estrogen on multiple components of the immune response; (2) its varied effects on different systems in which it appears pro-autoimmune, as in murine lupus, or anti-inflammatory, as in EAE; and (3) its effects on other hormones which are potentially immunomodulatory. Recent reports have shed light on the role of estrogen in the modulation of lymphocyte survival and expansion and in the elaboration of Th1 versus Th2 cytokines and on the mechanisms by which estrogen can activate via multiple signaling and genomic pathways in immune cells.

Effect of ovarian hormones on periodical changes in immune resistance associated with estrous cycle in the beagle bitch

In bitches, the onset of pyometra, an infection of the uterus, characteristically occurs in the first half of the diestrous stage in the estrous cycle, in which the blood concentration of progesterone peaks and that of estradiol-17beta is lowest. To investigate the immunological mechanisms governing stage-specific onset of pyometra, peripheral blood mononuclear cells (PBMNCs) were collected from beagle bitches during different stages of the estrous cycle and examined using various immunological assays. When we examined the proliferative response of PBMNCs to PYO-252, that is a clone of Escherichia coli isolated from the uterus of a dog afflicted with pyometra, the response of PBMNCs significantly decreased in the first half (day 10) of diestrus, but increased in proestrus/estrus. No significant differences were observed in the responses to concanavaline A between stages of the cycle. Throughout the estrous cycle, canine PBMNCs did not respond to lipopolysaccharide derived from E. coli. The response of PBMNCs collected in anestrus to PYO-252 was significantly enhanced upon the addition of estradiol-17beta to the culture. In contrast, these responses were significantly suppressed in the presence of progesterone. Progesterone progenitor or metabolite molecules, which have a low affinity for the progesterone receptor, did not affect proliferative responses. Expression of gamma interferon (IFNgamma) in response to PYO-252 was also significantly enhanced by estradiol-17beta, but suppressed by progesterone. This evidence suggests that in the first half of the diestrous stage, suppressed activity of cellular immunity results from increasing progesterone concentration and minimal estrogen release. This marked decrease of immune resistance allows the expansion of E. coli, which enter the uterine cavity through the loosened cervical canal during estrus, leading to pyometra onset.

Oxytocin and estrogen receptor alpha and beta knockout mice provide discriminably different odor cues in behavioral assays

Social behavior involves both the recognition and pro-duction of social cues. Mice with selective deletion(knockout) of either the gene for oxytocin (OT) or genes for the estrogen receptor (ER) -c or -B display impaired social recognition. In this study we demonstrate that these gene knockout mice also provide discriminably different social stimuli in behavioral assays. In an odor choice test, which is a measure of social interest and discrimination, outbred female Swiss-Webster mice discriminated the urine odors of male knock-outs IKO: OTKO, alphaERKO, betaERKO) from the odors of their wildtype littermates (WT: OTWT, alphaERWT, betaERWT). Females showed marked initial choices of the urine odors of OTWT and betaERWT males over those of OTKOand PERKO males, and alphaERKO males over alphaERWT males. The odors of OTKO and betaERKO males also induced aversive, analgesic responses, with the odors of WTs having no significant effects. Odors of both the alphaERWT andalphaERKO males induced aversive, analgesic responses,with the odors of the WT inducing significantly greater analgesia. The odors of restraint stressed WT and KO males also elicited analgesia with, again, females dis-playing significantly greater responses to the odors of stressed OTKO and betaERKO males than their WTs, and significantly lower analgesia to the odors of stressedalphaERKO than alphaERWT males. These findings show that the KO mice are discriminated from their WTs on the basis of odor and that the various KOs differ in the relative attractiveness/aversiveness of their odors. Therefore, in behavioral assays one causal route by which gene inactivation alters the social behavior of knockout mice may be mediated through the partners'modified responses to their odors.

Natural killer cell activity and sensitivity to positive and negative modulation in uncomplicated obese subjects: relationships to leptin and diet composition

BACKGROUND

Natural killer (NK) cells are a key component of innate immunity; their activity is modulated by cytokines and hormones and is influenced by diet. In obesity, a higher risk of cancer and infections has been demonstrated. Studies on NK cell activity have yielded inconsistent results; NK cell sensitivity to modulators has not been assessed before.

OBJECTIVE

In this case-control study, we assessed both spontaneous NK cell activity and responsiveness to positive (interleukin (IL)-2) and negative (cortisol) modulators in uncomplicated obesity; we searched for correlations between NK cell activity and anthropometric, dietary and metabolic variables.

METHODS

In all, 21 obese (six males/15 females) and 21 age- and sex-matched healthy nonobese subjects underwent clinical examination and dietary and laboratory analyses. Spontaneous and modulated NK activities of peripheral blood mononuclear cells were measured by enzyme-release cytotoxicity assay.

RESULTS

Spontaneous NK cell activity was not different in obese subjects vs controls. IL-2 stimulated and cortisol inhibited NK cell activity in both populations. Cortisol-dependent inhibition was lower in the obese than in the control group (-24.4+/-2.9 vs -38.6+/-3.3%, P=0.002), but decreased sensitivity was restricted to women (P=0.0007). In obese subjects, cortisol-dependent inhibition negatively correlated with serum leptin levels (r=-0.54, P=0.02) and, in women, with body mass index (r=-0.63, P=0.01); IL-2-dependent stimulation positively correlated with dietary carbohydrates (r=0.61, P=0.005) and serum LDL levels (r=0.55, P=0.009) and negatively correlated with dietary lipids (r=-0.71, P=0.0006).

CONCLUSION

Spontaneous and IL-2-inducible NK cell activity is normal in uncomplicated obesity. Sensitivity to IL-2 correlates with fat and carbohydrate intake. Sensitivity to glucocorticoids negatively correlates with serum leptin levels and is significantly diminished in obese women, in whom it correlates with body mass index.

Neurotransmitters regulate the migration and cytotoxicity in natural killer cells

Natural killer (NK) cells and cytotoxic T lymphocytes (CTL), the functional coordination of which are governed by various signal substances, are crucial in the body's defense of tumor and virus-infected cells. We investigated the role of various neurotransmitters and hormones on the regulation of functional parameters, including NK cell cytotoxicity, and the migration of NK cells and CTL within a three-dimensional collagen lattice. Using peripheral blood CTL and NK cells, we show that the neurotransmitters endorphin, histamine and substance P increase NK cell cytotoxicity, while norepinephrine inhibits cytotoxicity. Moreover, substance P reduces migratory activity, while norepinephrine increases NK cell and CTL migration. Furthermore, all three steroid hormones which were investigated, namely cortisone, testosterone, and estradiol, had regulatory influence on both cytotoxicity and migration of NK cells. These results further specify the functional basis of the complex interconnection between the immune and neuro-endocrine systems.

Estrogen receptor-alpha deficiency promotes increased TNF-alpha secretion and bacterial killing by murine macrophages in response to microbial stimuli in vitro

In this series of studies, we determined the potential role of intracellular estrogen receptors (ER), ERalpha and ERbeta, on macrophage function in response to bacterial stimuli. The sex hormone 17beta-estradiol (E(2)) and ER have been shown to modulate inflammatory responses as well as T helper cell type 1 (TH1)/TH2 responses. The mechanisms E(2) and its receptors use to alter these immune functions remain largely unknown. ERalpha and ERbeta possess complex actions in tissues where they are expressed. We have characterized the receptor repertoire of murine dendritic cells and thioglycollate-elicited peritoneal macrophages (PM). Both cell types express mRNA for ERalpha. Neither cell type expressed detectable amounts of ERbeta mRNA, as determined by reverse transcriptase-polymerase chain reaction using exon-specific primers spanning each of the seven intron/exon junctions. Primary macrophages from ERalpha- and ERbeta-deficient severe combined immunodeficiency mice [ERalpha knockout (KO) and ERssKO, respectively] were used to delineate the effects and potential mechanisms via which steroid receptors modulate macrophage function. ERalpha-deficient PM exposed ex vivo to lipopolysaccharide or Mycobacterium avium exhibited significant increases in tumor necrosis factor alpha (TNF-alpha) secretion as well as reduction in bacterial load when compared with wild-type (WT) PM. In contrast, ERbeta-deficient PM possessed no significant difference in TNF-alpha secretion or in bacterial load when compared with WT littermates. These studies suggest that ERalpha, but not ERbeta, modulates murine PM function.

Dietary soy phytoestrogens and ERalpha signalling modulate interferon gamma production in response to bacterial infection

Diets rich in soy phytoestrogens have many potential health benefits but isoflavones such as genistein may suppress cell mediated immune function. The effect of dietary phytoestrogens on the host response to infection has not been extensively examined. Mice were fed a diet containing soy phytoestrogens and infected with Mycobacterium avium to establish a chronic infection and inflammatory response. As phytoestrogens may act through classical oestrogen receptors (ER), mice deficient in ERalpha signalling and wild type mice were evaluated for a panel of Type 1-associated cytokines (IFNgamma, IL-12 and IL-18) in the spleen. IFNgamma production in the spleen was increased approximately 4-fold in ERalpha-deficient mice fed a casein-based diet over wild type mice fed a casein-based diet (P < 0.05), suggesting a role for ERalpha in suppressing IFNgamma production. IL-18 levels in spleens of wild type mice were decreased compared to ERalpha-deficient mice on a casein diet. Splenic IL-12 and IL-18 levels were not affected in wild type and ERalpha-deficient mice on the phytoestrogen containing diets, with the exception that whole soy increased IL-12 levels in the tissues of ERalpha deficient mice. We conclude that ERalpha and dietary phytoestrogens can influence production of key regulatory cytokines in response to chronic bacterial infection.

Coordinate regulation of lymphocyte-endothelial interactions by pregnancy-associated hormones

Precursors of uterine NK cells home to the uterus during early pregnancy from multiple lymphohemopoietic sources. In mouse uterine tissue, pregnancy markedly up-regulates both L-selectin- and alpha(4) integrin-dependent adhesion pathways for circulating human CD56(bright) cells, the phenotype of human uterine NK cells. Based on roles for these adhesion molecules in lymphocyte homing, we examined effects of pregnancy or the steroid hormones 17beta-estradiol or progesterone on lymphocyte-endothelial interactions in secondary lymphoid tissues and in uterus. From preimplantation gestation day 3, specialized high endothelial venules in peripheral lymph nodes and Peyer's patches supported elevated L-selectin and alpha(4)beta(7) integrin-dependent lymphocyte adhesion under shear throughout pregnancy, as compared with high endothelial venules of virgin or postpartum donors. Squamous endothelium from nonlymphoid tissue was not affected. Pregnancy-equivalent endothelial responses were observed in lymph nodes and Peyer's patches from ovariectomized mice receiving 17beta-estradiol and/or progesterone replacement therapy. Adhesion of human CD56(bright) cells to uteri from pregnant or hormone-treated ovariectomized mice was enhanced through L-selectin- and alpha(4) integrin-dependent mechanisms and involved multiple vascular adhesion molecules including mucosal addressin cell adhesion molecule-1, VCAM-1, and peripheral lymph node addressin. Analysis of Tie2-green fluorescence protein transgenic mice demonstrated that CD56(bright) cells adhered primarily to vascular endothelium within the decidua basalis. Microdomain localization of adhesion involving large clusters of lymphocytes was induced on uteri from natural matings, but not pseudopregnancy. Steroid hormones also had independent effects on L-selectin function in splenic lymphocytes that mimicked physiological stimulation induced by pregnancy or fever-range temperatures. These results provide the first evidence for coordinated, organ-specific, steroid hormone-induced changes in lymphocyte homing mechanisms that could contribute to local and systemic immune responses during pregnancy.

In vitro and in vivo regulation of antioxidant response element-dependent gene expression by estrogens

Understanding estrogen's regulation of phase II detoxification enzymes is important in explaining how estrogen exposure increases the risk of developing certain cancers. Phase II enzymes such as glutathione-S-transferases (GST) and quinone reductase protect against developing chemically induced cancers by metabolizing reactive oxygen species. Phase II enzyme expression is regulated by a cis-acting DNA sequence, the antioxidant response element (ARE). It has previously been reported that several antiestrogens, but not 17beta-estradiol, could regulate ARE-mediated gene transcription. Our goal was to determine whether additional estrogenic compounds could regulate ARE-mediated gene expression both in vitro and in vivo. We discovered that physiological concentrations (10 nm) of 17beta-estradiol repressed GST Ya ARE-dependent gene expression in vitro. Treatment with other endogenous and anti-, xeno-, and phytoestrogens showed that estrogen receptor/ARE signaling is ligand, receptor subtype, and cell type specific. Additionally, GST and quinone reductase activities were significantly lowered in a dose-dependent manner after 17beta-estradiol exposure in the uteri of mice. In conclusion, we have shown that 17beta-estradiol, and other estrogens, down-regulate phase II enzyme activities. We propose estrogen-mediated repression of phase II enzyme activities may increase cellular oxidative DNA damage that ultimately can result in the formation of cancer in some estrogen-responsive tissues.

Regulation of nitric oxide-dependent vasodilation in coronary arteries of estrogen receptor-alpha-deficient mice

Estrogen has been shown to increase endothelium-dependent vasodilation and expression of endothelial nitric oxide (NO) synthase (eNOS); however, the role of estrogen receptors in mediating estrogen effects on endothelial function remains to be elucidated. The purpose of this study was to test the hypothesis that estrogen modulates NO-dependent vasodilation of coronary arteries through its action on estrogen receptor-alpha (ER-alpha) to increase protein levels of eNOS and Cu/Zn superoxide dismutase (SOD-1). Vasodilation to acetylcholine (ACh) and sodium nitroprusside was assessed in isolated coronary arteries from intact and ovariectomized female wild-type (WT) and ER-alpha knockout (ERalphaKO) mice. Protein levels for eNOS and SOD-1 were also evaluated. Vasodilation to ACh was not significantly altered in ERalphaKO mice compared with WT mice. Ovariectomy reduced responsiveness to ACh in ERalphaKO mice but not WT mice. Responses to sodium nitroprusside were not altered by disruption of ER-alpha or by ovariectomy. Supplementation with estrogen restored ACh-induced vasodilation in ovariectomized ERalphaKO mice. eNOS protein was reduced in ERalphaKO mice compared with WT mice. Ovariectomy caused a further reduction in eNOS protein in ERalphaKO mice, but this reduction was reversed by estrogen treatment. SOD-1 protein levels were increased by disruption of ER-alpha. Ovariectomy reduced SOD-1 protein in ERalphaKO mice, but this reduction was partially reversed by estrogen replacement. These results suggest that estrogen modulation of eNOS protein content is mediated in part through ER-alpha. NO-dependent responses are preserved in ERalphaKO mice, possibly through increased SOD-1 expression and enhanced bioavailability of NO.

Functional analysis of murine uterine natural killer cells genetically devoid of oestrogen receptors

Uterine Natural Killer (uNK) cell differentiation in vivo requires oestrogen (E) priming prior to progesterone (P). Hybridomas between uNK precursor and SP2/0 cells express message for E receptor (ER)alpha but nor PR. However, mature, rodent and human uNK cells lack these receptors. To functionally assess requirements for uNK cell expression of ERalpha or ERbeta during precursor differentiation, marrow was transplanted from either ERalpha(o/o) (alphaERKO) or ERbeta(o/o) (betaERKO) mice into alymphoid RAG-2(o/o)/gammac(o/o) females. Recipients were mated and their implantation sites were examined by light microscopy, morphometry and ultrastructure. High numbers of uNK cells were established from each donor strain. Graft-derived uNK cells were similar in number and morphology to uNK cells of normal mice, suggesting that neither alpha- nor beta-ER is required for uNK precursor cell differentiation. Induction of spiral artery modification in the transplant recipients indicated that graft-derived uNK cells had functional properties. A novel technique for rapid isolation of highly purified uNK cells from normal mice using Dolichos biflorus agglutinin (DBA) lectin-conjugated magnetic beads was employed to obtain RNA. Expression of alpha- and beta-ER was absent by RT-PCR from NK cells isolated from the uterus, supporting the conclusions from the in vivo study.