Differential roles of estrogen receptors α and β in control of B-cell maturation and selection

Updated advances of linking psychosocial factors and sex hormones with systemic lupus erythematosus susceptibility and development

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease that primarily affects women, especially those of reproductive age. Genetics, environment, and gene-environment interactions play key roles in the development of SLE. Despite the numerous susceptibility genes of SLE identified to date, gene therapy is far from a clinical reality. Thus, more attention should be paid to the risk factors and underlying mechanisms of SLE. Currently, it is reported that psychosocial factors and sex hormones play vital roles in patients with SLE, which still need further investigated. The purpose of this review is to update the roles and mechanisms of psychosocial factors and sex hormones in the susceptibility and development of SLE. Based on review articles and reports in reputable peer-reviewed journals and government websites, this paper summarized psychosocial factors (e.g., alexithymia, depression, anxiety, negative emotions, and perceived stress) and sex hormones (e.g., estrogens, progesterone, androgens, and prolactin) involved in SLE. We further explore the mechanisms linking these factors with SLE susceptibility and development, which can guide the establishment of practical measures to benefit SLE patients and offer new ideas for therapeutic strategies.

Gender differences in clinical presentation and vascular pattern in patients with Takayasu arteritis

Objective: To compare clinical characteristics and pattern of vascular involvement at disease onset according to gender specificity in patients with Takayasu arteritis (TA).Methods: Data from 117 TA patients (11 male, 106 female), diagnosed according to the American College of Rheumatology criteria, from our centre were retrospectively collected. Differences between men and women regarding demographic features, diagnostic delay, signs and symptoms attributed to TA, and arteries involved at diagnosis were compared. Data were obtained from three published articles describing gender differences in TA. A global analysis of these three cohorts plus ours (a total of 578 patients; 108 men, 470 women) was performed.Results: In our TA cohort, age at disease onset and age at diagnosis were not significantly different between genders. Diagnostic delay was higher in men. Male patients showed higher involvement of iliac arteries (right, p = 0.016; left, p = 0.021); females suffered more frequently from upper limb claudication (p = 0.026). In the overall analysis, men had higher prevalence of arterial hypertension (p = 0.007) and more frequent involvement of abdominal aorta (p = 0.026), renal arteries (right, p < 0.001; left, p < 0.001), and iliac arteries (right, p = 0.009; left, p = 0.002). Women more frequently exhibited upper limb claudication (p = 0.042) and involvement of left subclavian artery (p = 0.005), carotid arteries (right, p < 0.001; left, p < 0.001), and supradiaphragmatic aorta (ascending, p = 0.050; arch, p < 0.001; descending, p = 0.003). Inflammatory markers were more frequently raised in women (p = 0.005).Conclusions: In TA patients, gender has a strong influence on pattern of vascular involvement and consequently on clinical presentation. Specifically, women have a higher involvement of the supradiaphragmatic vessels, whereas in men the abdominal vessels are more frequently affected.

Sex Differences in Older Adults' Immune Responses to Seasonal Influenza Vaccination

Background: Sex differences in immune responses to influenza vaccine may impact efficacy across populations. Methods: In a cohort of 138 older adults (50-74 years old), we measured influenza A/H1N1 antibody titers, B-cell ELISPOT response, PBMC transcriptomics, and PBMC cell compositions at 0, 3, and 28 days post-immunization with the 2010/11 seasonal inactivated influenza vaccine. Results: We identified higher B-cell ELISPOT responses in females than males. Potential mechanisms for sex effects were identified in four gene clusters related to T, NK, and B cells. Mediation analysis indicated that sex-dependent expression in T and NK cell genes can be partially attributed to higher CD4+ T cell and lower NK cell fractions in females. We identified strong sex effects in 135 B cell genes whose expression correlates with ELISPOT measures, and found that cell subset differences did not explain the effect of sex on these genes' expression. Post-vaccination expression of these genes, however, mediated 41% of the sex effect on ELISPOT responses. Conclusions: These results improve our understanding of sexual dimorphism in immunity and influenza vaccine response.

Sex Hormones in Acquired Immunity and Autoimmune Disease

Women have stronger immune responses to infections and vaccination than men. Paradoxically, the stronger immune response comes at a steep price, which is the high incidence of autoimmune diseases in women. The reasons why women have stronger immunity and higher incidence of autoimmunity are not clear. Besides gender, sex hormones contribute to the development and activity of the immune system, accounting for differences in gender-related immune responses. Both innate and adaptive immune systems bear receptors for sex hormones and respond to hormonal cues. This review focuses on the role of sex hormones particularly estrogen, in the adaptive immune response, in health, and autoimmune disease with an emphasis on systemic lupus erythematosus.

Female predisposition to TLR7-driven autoimmunity: gene dosage and the escape from X chromosome inactivation

Women develop stronger immune responses than men, with positive effects on the resistance to viral or bacterial infections but magnifying also the susceptibility to autoimmune diseases like systemic lupus erythematosus (SLE). In SLE, the dosage of the endosomal Toll-like receptor 7 (TLR7) is crucial. Murine models have shown that TLR7 overexpression suffices to induce spontaneous lupus-like disease. Conversely, suppressing TLR7 in lupus-prone mice abolishes SLE development. TLR7 is encoded by a gene on the X chromosome gene, denoted TLR7 in humans and Tlr7 in the mouse, and expressed in plasmacytoid dendritic cells (pDC), monocytes/macrophages, and B cells. The receptor recognizes single-stranded RNA, and its engagement promotes B cell maturation and the production of pro-inflammatory cytokines and antibodies. In female mammals, each cell randomly inactivates one of its two X chromosomes to equalize gene dosage with XY males. However, 15 to 23% of X-linked human genes escape X chromosome inactivation so that both alleles can be expressed simultaneously. It has been hypothesized that biallelic expression of X-linked genes could occur in female immune cells, hence fostering harmful autoreactive and inflammatory responses. We review here the current knowledge of the role of TLR7 in SLE, and recent evidence demonstrating that TLR7 escapes from X chromosome inactivation in pDCs, monocytes, and B lymphocytes from women and Klinefelter syndrome men. Female B cells where TLR7 is thus biallelically expressed display higher TLR7-driven functional responses, connecting the presence of two X chromosomes with the enhanced immunity of women and their increased susceptibility to TLR7-dependent autoimmune syndromes.

piMGM: incorporating multi-source priors in mixed graphical models for learning disease networks

Motivation

Learning probabilistic graphs over mixed data is an important way to combine gene expression and clinical disease data. Leveraging the existing, yet imperfect, information in pathway databases for mixed graphical model (MGM) learning is an understudied problem with tremendous potential applications in systems medicine, the problems of which often involve high-dimensional data.

Results

We present a new method, piMGM, which can learn with accuracy the structure of probabilistic graphs over mixed data by appropriately incorporating priors from multiple experts with different degrees of reliability. We show that piMGM accurately scores the reliability of prior information from a given expert even at low sample sizes. The reliability scores can be used to determine active pathways in healthy and disease samples. We tested piMGM on both simulated and real data from TCGA, and we found that its performance is not affected by unreliable priors. We demonstrate the applicability of piMGM by successfully using prior information to identify pathway components that are important in breast cancer and improve cancer subtype classification.

Availability and implementation

http://www.benoslab.pitt.edu/manatakisECCB2018.html.

Supplementary information

Supplementary data are available at Bioinformatics online.

Testosterone is an endogenous regulator of BAFF and splenic B cell number

Testosterone deficiency in men is associated with increased risk for autoimmunity and increased B cell numbers through unknown mechanisms. Here we show that testosterone regulates the cytokine BAFF, an essential survival factor for B cells. Male mice lacking the androgen receptor have increased splenic B cell numbers, serum BAFF levels and splenic Baff mRNA. Testosterone deficiency by castration causes expansion of BAFF-producing fibroblastic reticular cells (FRCs) in spleen, which may be coupled to lower splenic noradrenaline levels in castrated males, as an α-adrenergic agonist decreases splenic FRC number in vitro. Antibody-mediated blockade of the BAFF receptor or treatment with the neurotoxin 6-hydroxydopamine revert the increased splenic B cell numbers induced by castration. Among healthy men, serum BAFF levels are higher in men with low testosterone. Our study uncovers a previously unrecognized regulation of BAFF by testosterone and raises important questions about BAFF in testosterone-mediated protection against autoimmunity.

Testosterone deficiency is associated with autoimmunity and increased B cell numbers, but the underlying mechanism is unclear. Here the authors show that testosterone may modulate the production of B cell survival factor BAFF by fibroblastic reticular cells via regulation of splenic neurotransmitter levels.

Estrogen induces St6gal1 expression and increases IgG sialylation in mice and patients with rheumatoid arthritis: a potential explanation for the increased risk of rheumatoid arthritis in postmenopausal women

BACKGROUND

Rheumatoid arthritis (RA) preferentially affects women, with the peak incidence coinciding with estrogen decrease in menopause. Estrogen (E2) may therefore have intrinsic immune-regulatory properties that vanish with menopause. Fc sialylation is a crucial factor determining the inflammatory effector function of antibodies. We therefore analyzed whether E2 affects immunoglobulin G (IgG) sialylation.

METHODS

Postmenopausal (ovariectomized) mice were immunized with ovalbumin and treated with E2 or vehicle. Total and ovalbumin-specific IgG concentrations, sialylation, and Fcγ receptor expression were analyzed. Postmenopausal women with RA receiving hormone replacement therapy, including E2, or no treatment were analyzed for IgG sialylation. Furthermore, effects of E2 on the expression of the sialylation enzyme β-galactoside α2,6-sialyltransferase 1 (St6Gal1) were studied in mouse and human antibody-producing cells.

RESULTS

E2 treatment significantly increased Fc sialylation of total and ovalbumin-specific IgG in postmenopausal mice. Furthermore, E2 led to increased expression of inhibitory Fcγ receptor IIb on bone marrow leukocytes. Treatment with E2 also increased St6Gal1 expression in mouse and human antibody-producing cells, providing a mechanistic explanation for the increase in IgG-Fc sialylation. In postmenopausal women with RA, treatment with E2 significantly increased the Fc sialylation of IgG.

CONCLUSIONS

E2 induces anti-inflammatory effector functions in IgG by inducing St6Gal1 expression in antibody-producing cells and by increasing Fc sialylation. These observations provide a mechanistic explanation for the increased risk of RA in conditions with low estrogen levels such as menopause.

Natural Anti-Estrogen Receptor Alpha Antibodies Able to Induce Estrogenic Responses in Breast Cancer Cells: Hypotheses Concerning Their Mechanisms of Action and Emergence

The detection of human anti-estrogen receptor α antibodies (ERαABs) inducing estrogenic responses in MCF-7 mammary tumor cells suggests their implication in breast cancer emergence and/or evolution. A recent report revealing a correlation between the titer of such antibodies in sera from patients suffering from this disease and the percentage of proliferative cells in samples taken from their tumors supports this concept. Complementary evidence of the ability of ERαABs to interact with an epitope localized within the estradiol-binding core of ERα also argues in its favor. This epitope is indeed inserted in a regulatory platform implicated in ERα-initiated signal transduction pathways and transcriptions. According to some experimental observations, two auto-immune reactions may already be advocated to explain the emergence of ERαABs: one involving probably the idiotypic network to produce antibodies acting as estrogenic secretions and the other based on antibodies able to abrogate the action of a natural ERα inhibitor or to prevent the competitive inhibitory potency of released receptor degradation products able to entrap circulating estrogens and co-activators. All of this information, the aspect of which is mainly fundamental, may open new ways in the current tendency to combine immunological and endocrine approaches for the management of breast cancer.

Targeting estrogen/estrogen receptor alpha enhances Bacillus Calmette-Guérin efficacy in bladder cancer

Recent studies showed the potential linkage of estrogen/estrogen receptor signaling with bladder tumorigenesis, yet detailed mechanisms remain elusive. Here we found a new potential therapy with the combination of Bacillus Calmette Guerin (BCG) and the anti-estrogen ICI 182,780 led to better suppression of bladder cancer (BCa) than BCG alone. Mechanism dissection found ICI 182,780 could promote BCG attachment/internalization to the BCa cells through increased integrin-α5β1 expression and IL-6 release, which may enhance BCG-induced suppression of BCa cell growth via recruiting more monocytes/macrophages to BCa cells and increased TNF-α release. Consistently, in vivo studies found ICI 182,780 could potentiate the anti-BCa effects of BCG in the carcinogen-induced mouse BCa models. Together, these in vitro and in vivo results suggest that combining BCG with anti-estrogen may become a new therapeutic approach with better efficacy to suppress BCa progression and recurrence.

HSC extrinsic sex-related and intrinsic autoimmune disease-related human B-cell variation is recapitulated in humanized mice

B cells play a major role in antigen presentation and antibody production in the development of autoimmune diseases, and some of these diseases disproportionally occur in females. Moreover, immune responses tend to be stronger in female vs male humans and mice. Because it is challenging to distinguish intrinsic from extrinsic influences on human immune responses, we used a personalized immune (PI) humanized mouse model, in which immune systems were generated de novo from adult human hematopoietic stem cells (HSCs) in immunodeficient mice. We assessed the effect of recipient sex and of donor autoimmune diseases (type 1 diabetes [T1D] and rheumatoid arthritis [RA]) on human B-cell development in PI mice. We observed that human B-cell levels were increased in female recipients regardless of the source of human HSCs or the strain of immunodeficient recipient mice. Moreover, mice injected with T1D- or RA-derived HSCs displayed B-cell abnormalities compared with healthy control HSC-derived mice, including altered B-cell levels, increased proportions of mature B cells and reduced CD19 expression. Our study revealed an HSC-extrinsic effect of recipient sex on human B-cell reconstitution. Moreover, the PI humanized mouse model revealed HSC-intrinsic defects in central B-cell tolerance that recapitulated those in patients with autoimmune diseases. These results demonstrate the utility of humanized mouse models as a tool to better understand human immune cell development and regulation.

Ratio of Circulating Estrogen Receptors Beta and Alpha (ERβ/ERα) Indicates Endoscopic Activity in Patients with Crohn's Disease

BACKGROUND

Data supporting a role of female hormones and/or their receptors in inflammatory bowel disease (IBD) are increasing, but most of them are derived from animal models. Estrogen receptors alpha (ERα) and beta (ERβ) participate in immune and inflammatory response, among a variety of biological processes. Their effects are antagonistic, and the net action of estrogens may depend on their relative proportions.

AIM

To determine the possible association between the balance of circulating ERβ and ERα (ERβ/ERα) and IBD risk and activity.

METHODS

Serum samples from 145 patients with IBD (79 Crohn's disease [CD] and 66 ulcerative colitis [UC]) and 39 controls were retrospectively studied. Circulating ERα and ERβ were measured by ELISA. Disease activities were assessed by clinical and endoscopic indices specific for CD and UC.

RESULTS

Low values of ERβ/ERα ratio were directly associated with clinical (p = 0.019) and endoscopic (p = 0.002) disease activity. Further analyses by type of IBD confirmed a strong association between low ERβ/ERα ratio and CD clinical (p = 0.011) and endoscopic activity (p = 0.002). The receiver operating curve (ROC) analysis showed that an ERβ/ERα ratio under 0.85 was a good marker of CD endoscopic activity (area under the curve [AUC]: 0.84; p = 0.002; sensitivity: 70%; specificity: 91%). ERβ/ERα ratio was not useful to predict UC activity.

CONCLUSIONS

An ERβ/ERα ratio under 0.85 indicated CD endoscopic activity. The determination of serum ERβ/ERα might be a useful noninvasive screening tool for CD endoscopic activity.

Sex differences in stroke across the lifespan: The role of T lymphocytes

Stroke is a sexually dimorphic disease. Ischemic sensitivity changes throughout the lifespan and outcomes depend largely on variables like age, sex, hormonal status, inflammation, and other existing risk factors. Immune responses after stroke play a central role in how these factors interact. Although the post-stroke immune response has been extensively studied, the contribution of lymphocytes to stroke is still not well understood. T cells participate in both innate and adaptive immune responses at both acute and chronic stages of stroke. T cell responses also change at different ages and are modulated by hormones and sex chromosome complement. T cells have also been implicated in the development of hypertension, one of the most important risk factors for vascular disease. In this review, we highlight recent literature on the lymphocytic responses to stroke in the context of age and sex, with a focus on T cell response and the interaction with important stroke risk factors.

Recruited mast cells in the tumor microenvironment enhance bladder cancer metastasis via modulation of ERβ/CCL2/CCR2 EMT/MMP9 signals

Early clinical studies suggested that infiltrating mast cells could be associated with a poor outcome in bladder cancer (BCa) patients. The mechanisms of how mast cells influence the BCa progression, however, are unclear. Using the human clinical BCa sample survey and in vitro co-culture systems, we found BCa cells could recruit more mast cells than the surrounding non-malignant urothelial cells. The consequences of this better recruitment of mast cells toward BCa cells could then enhance BCa cell invasion. Mechanism dissection revealed that the enhanced BCa cell invasion could function via up-regulation of the estrogen receptor beta (ER&beta;) in both mast cells and BCa cells, which resulted in the increased CCL2/CCR2/EMT/MMP9 signals. Using the pre-clinical mouse BCa model, we further validated the mast cell-promoted BCa invasion. Interruption of the newly identified ER&beta;/CCL2/CCR2/EMT/MMP9 pathway via either ER&beta;-siRNA, ER&beta; antagonist PHTPP, or CCR2 antagonist can effectively reverse the mast cell-enhanced BCa cells invasion. Together, our finding could lead to the development of an alternative new therapeutic approach to better treat BCa metastasis.

Estrogen receptor alpha promotes lupus in (NZB×NZW)F1 mice in a B cell intrinsic manner

Lupus is a systemic autoimmune disease characterized by the production of autoreactive antibodies against nuclear antigens. Women are disproportionately affected by lupus, and this sex bias is thought to be due, in large part, to the ability of estrogens to promote lupus pathogenesis. Previously, we have shown that global deletion of estrogen receptor alpha (ERα) significantly attenuated loss of tolerance, immune cell activation, autoantibody production, and the development of lupus nephritis. Here we show that targeted deletion of ERα specifically in B cells retards production of pathogenic autoantibodies and the development of nephritis in lupus-prone (NZB×NZW)F1 mice. Furthermore, we observed that ERα deletion in B cells was associated with decreased B cell activation in young, pre-autoimmune (NZB×NZW)F1 females. Altogether, these data suggest that ERα acts in a B cell-intrinsic manner to control B cell activation, autoantibody production, and lupus nephritis.

The immunoendocrinology of systemic lupus erythematosus

Immunoendocrinology or the study of the effects of sex steroids and sex chromatin on immune diseases was pioneered by Henry G. Kunkel. In the disease lupus (SLE) the prevalence of female disease is high; the sex ratio is 10 females to every male after puberty. Since Kunkel's death the influences of triggering epitopes like viruses, histocompatibility, the hypothalamic pituitary-adrenocortical axis, nervous system and the effect of sex steroids are all recognized as contributing factors to pathogenesis. It is too simple to say that sex and genetics are the final reason for the female predominance of SLE. Today the likely cause of the disease involves the epigenetics of sex chromatin and the factors detailed above.

Non-genomic oestrogen receptor signal in B lymphocytes: An approach towards therapeutic interventions for infection, autoimmunity and cancer

The non-genomic membrane bound oestrogen receptor (mER) regulates intracellular signals through receptor-ligand interactions. The mER, along with G-protein coupled oestrogen receptor GPR 30 (GPER), induces diverse cell signalling pathways in murine lymphocytes. The mER isoform ER-alpha46 has recently been demonstrated in human B and T lymphocytes as an analogue receptor for chemokine CCL18, the signalling events of which are not clearly understood. Ligand-induced mER and GPER signalling events are shared with BCR, CD19 mediated intracellular signalling through phospholipase C, PIP2/IP3/PI3 mediated activation of Akt, MAP kinase, and mTOR. Oestrogen has the ability to induce CD40-mediated activation of B cells. The complete signalling pathways of mER, GPR30 and their interaction with other signals are targeted areas for novel drug development in B cells during infection, autoimmunity and cancer. Therefore, an in depth investigation is critical for determining shared signal outputs during B cell activation. Here, we focus on the mode of action of membrane bound ER in B cells as therapeutic checkpoints.

Estrogen-mediated downregulation of AIRE influences sexual dimorphism in autoimmune diseases

Autoimmune diseases affect 5% to 8% of the population, and females are more susceptible to these diseases than males. Here, we analyzed human thymic transcriptome and revealed sex-associated differences in the expression of tissue-specific antigens that are controlled by the autoimmune regulator (AIRE), a key factor in central tolerance. We hypothesized that the level of AIRE is linked to sexual dimorphism susceptibility to autoimmune diseases. In human and mouse thymus, females expressed less AIRE (mRNA and protein) than males after puberty. These results were confirmed in purified murine thymic epithelial cells (TECs). We also demonstrated that AIRE expression is related to sexual hormones, as male castration decreased AIRE thymic expression and estrogen receptor α-deficient mice did not show a sex disparity for AIRE expression. Moreover, estrogen treatment resulted in downregulation of AIRE expression in cultured human TECs, human thymic tissue grafted to immunodeficient mice, and murine fetal thymus organ cultures. AIRE levels in human thymus grafted in immunodeficient mice depended upon the sex of the recipient. Estrogen also upregulated the number of methylated CpG sites in the AIRE promoter. Together, our results indicate that in females, estrogen induces epigenetic changes in the AIRE gene, leading to reduced AIRE expression under a threshold that increases female susceptibility to autoimmune diseases.

The Immune System Is a Natural Target for Estrogen Action: Opposing Effects of Estrogen in Two Prototypical Autoimmune Diseases

Analogous to other physiological systems, the immune system also demonstrates remarkable sex differences. Although the reasons for sex differences in immune responses are not precisely understood, it potentially involves differences in sex hormones (estrogens, androgens, and differential sex hormone receptor-mediated events), X-chromosomes, microbiome, epigenetics among others. Overall, females tend to have more responsive and robust immune system compared to their male counterparts. It is therefore not surprising that females respond more aggressively to self-antigens and are more susceptible to autoimmune diseases. Female hormone (estrogen or 17β-estradiol) can potentially act on all cellular subsets of the immune system through estrogen receptor-dependent and -independent mechanisms. This minireview highlights differential expression of estrogen receptors on immune cells, major estrogen-mediated signaling pathways, and their effect on immune cells. Since estrogen has varied effects in female-predominant autoimmune diseases such as multiple sclerosis and systemic lupus erythematosus, we will mechanistically postulate the potential differential role of estrogen in these chronic debilitating diseases.

17-β-estradiol affects BLyS serum levels and the nephritogenic autoantibody network accelerating glomerulonephritis in NZB/WF1 mice

Systemic lupus erythematosus (SLE) is an autoimmune disease that predominantly affects fertile women, suggesting sex hormones are involved in disease pathogenesis. B lymphocyte stimulator (BLyS) has been found to be elevated in SLE patients and to drive a lupus-like syndrome in transgenic mice. Our aim was to evaluate the effects of estrogen administration on BLyS and nephritogenic anti-C1q and anti-dsDNA antibodies in lupus-prone NZB/WF1 mice. We implanted pellets releasing 17-β-estradiol (18.8 µg/day) on the back side the ear of 10 NZB/WF1 mice (group 1), and compared them with 10 mice intraperitoneally injected with PBS 200 μl twice a week (group 2), as controls. We evaluated BLyS, anti-dsDNA and anti-C1q serum levels starting one week after pellet implantation. We also analyzed time to proteinuria onset, proteinuria-free survival and overall survival. Kidneys, spleen, liver and lungs were harvested for histological analysis. Mice were bred until natural death. BLyS serum levels were higher in group 1 than in group 2 mice at each evaluation. Group 1 mice developed nephritogenic antibodies and proteinuria significantly earlier and at higher levels than controls. Direct correlation between BLyS and anti-C1q (R (2 )= 0.6962, p < 0.0001) or anti-dsDNA (R (2 )= 0.5953, p < 0.0001), and between anti-C1q and anti-dsDNA autoantibodies (R (2 )= 0.5615, p < 0.0001) were found. Proteinuria-free and global survival rates were significantly lower in group 1 than in controls. Histological analyses showed more severe abnormalities in group 1 mice. Estrogen administration is associated with increased levels of BLyS as well as of anti-C1q and anti-dsDNA antibodies, leading to accelerated glomerulonephritis and disease progression in NZB/WF1 mice.

Bisphenol A (BPA) stimulates the interferon signaling and activates the inflammasome activity in myeloid cells

Environmental factors contribute to the development of autoimmune diseases, including systemic lupus erythematosus (SLE), which exhibits a strong female bias (female-to-male ratio 9:1). However, the molecular mechanisms remain largely unknown. Because a feedforward loop between the female sex hormone estrogen (E2) and type I interferon (IFN-α/β)-signaling induces the expression of certain p200-family proteins (such as murine p202 and human IFI16) that regulate innate immune responses and modify lupus susceptibility, we investigated whether treatment of myeloid cells with bisphenol A (BPA), an environmental estrogen, could regulate the p200-family proteins and activate innate immune responses. We found that treatment of murine bone marrow-derived cells (BMCs) and human peripheral blood mononuclear cells with BPA induced the expression of ERα and IFN-β, activated the IFN-signaling, and stimulated the expression of the p202 and IFI16 proteins. Further, the treatment increased levels of the NLRP3 inflammasome and stimulated its activity. Accordingly, BPA-treatment of BMCs from non lupus-prone C57BL/6 and the lupus-prone (NZB×NZW)F1 mice activated the type I IFN-signaling, induced the expression of p202, and activated an inflammasome activity. Our study demonstrates that BPA-induced signaling in the murine and human myeloid cells stimulates the type I IFN-signaling that results in an induction of the p202 and IFI16 innate immune sensors for the cytosolic DNA and activates an inflammasome activity. These observations provide novel molecular insights into the role of environmental BPA exposures in potentiating the development of certain autoimmune diseases such as SLE.

Mucosal B Cells Are Associated with Delayed SIV Acquisition in Vaccinated Female but Not Male Rhesus Macaques Following SIVmac251 Rectal Challenge

Many viral infections, including HIV, exhibit sex-based pathogenic differences. However, few studies have examined vaccine-related sex differences. We compared immunogenicity and protective efficacy of monomeric SIV gp120 with oligomeric SIV gp140 in a pre-clinical rhesus macaque study and explored a subsequent sex bias in vaccine outcome. Each immunization group (16 females, 8 males) was primed twice mucosally with replication-competent Ad-recombinants encoding SIV_smH4env/rev, SIV₂₃₉gag and SIV₂₃₉nefΔ_1–13 and boosted twice intramuscularly with SIV_mac239 monomeric gp120 or oligomeric gp140 in MF59 adjuvant. Controls (7 females, 5 males) received empty Ad and MF59. Up to 9 weekly intrarectal challenges with low-dose SIV_mac251 were administered until macaques became infected. We assessed vaccine-induced binding, neutralizing, and non-neutralizing antibodies, Env-specific memory B cells and plasmablasts/plasma cells (PB/PC) in bone marrow and rectal tissue, mucosal Env-specific antibodies, and Env-specific T-cells. Post-challenge, only one macaque (gp140-immunized) remained uninfected. However, SIV acquisition was significantly delayed in vaccinated females but not males, correlated with Env-specific IgA in rectal secretions, rectal Env-specific memory B cells, and PC in rectal tissue. These results extend previous correlations of mucosal antibodies and memory B cells with protective efficacy. The gp140 regimen was more immunogenic, stimulating elevated gp140 and cyclic V2 binding antibodies, ADCC and ADCP activities, bone marrow Env-specific PB/PC, and rectal gp140-specific IgG. However, immunization with gp120, the form of envelope immunogen used in RV144, the only vaccine trial to show some efficacy, provided more significant acquisition delay. Further over 40 weeks of follow-up, no gp120 immunized macaques met euthanasia criteria in contrast to 7 gp140-immunized and 2 control animals. Although males had higher binding antibodies than females, ADCC and ADCP activities were similar. The complex challenge outcomes may reflect differences in IgG subtypes, Fc glycosylation, Fc-R polymorphisms, and/or the microbiome, key areas for future studies. This first demonstration of a sex-difference in SIV vaccine-induced protection emphasizes the need for sex-balancing in vaccine trials. Our results highlight the importance of mucosal immunity and memory B cells at the SIV exposure site for protection.

Viral infections can have different disease courses in men and women. Following HIV infection, women generally exhibit lower viral loads and higher CD4 counts than men, but paradoxically progress faster to AIDS. Sex differences result from effects of X-linked genes and hormonal influences, and are believed to be largely based on immune response differences. Nevertheless, little is known about potential sex differences following vaccination. Here we report for the first time a sex bias in response to a SIV vaccine in rhesus macaques, showing that female animals were better protected against acquisition of SIV compared to males. The vaccine-induced immune responses that contributed to this better protection were viral-specific antibodies and immune antibody-secreting B cells, both at the local rectal site of SIV exposure. These results suggest that HIV/SIV vaccines should be better designed to target mucosal exposure sites. Additionally, they indicate that more vaccine studies should include animals of both sexes to address potential differences. Our study also illustrates that inclusion of both sexes can lead to greater complexity in vaccine trial outcomes, necessitating more in depth analyses. However, we believe sex balancing to be particularly important, as approximately 50% of HIV infections worldwide occur in women.

Estrogen receptor alpha prevents bladder cancer via INPP4B inhibited akt pathway in vitro and in vivo

Clinical reports show males have a higher bladder cancer (BCa) incidence than females. The sexual difference of BCa occurrence suggests that estrogen and its receptors may affect BCa development. Estrogen receptor alpha (ERα) is the classic receptor to convey estrogen signaling, however, the function of ERα in BCa development remains largely unknown. To understand the in vivo role of ERα in BCa development, we generated total and urothelial specific ERα knockout mice (ERαKO) and used the pre- carcinogen BBN to induce BCa. Earlier reports showed that ERα promotes breast and ovarian cancers in females. Surprisingly and of clinical importance, our results showed that ERα inhibits BCa development and loss of the ERα gene results in an earlier onset and higher incidence of BBN-induced in vivo mouse BCa. Supportively, carcinogen induced malignant transformation ability was reduced in ERα expressing urothelial cells as compared to ERα negative cells. Mechanism studies suggest that ERα could control the expression of INPP4B to reduce AKT activity and consequently reduce BCa cell growth. In addition, IHC staining of clinical sample analyses show that INPP4B expression, in correlation with reduced ERα, is significantly reduced in human BCa specimens. Together, this is the first report using the in vivo cre-loxP gene knockout mouse model to characterize ERα roles in BCa development. Our studies provide multiple in vitro cell studies and in vivo animal model data as well as human BCa tissue analyses to prove ERα plays a protective role in BCa initiation and growth at least partly via modulating the INPP4B/Akt pathway.

Sex, the aging immune system, and chronic disease

The immune systems of men and women differ in significant ways, especially after puberty. In particular, females are generally more prone to autoimmunity, but experience lower rates of infections and chronic inflammatory disease. Sex hormones, genes encoded on the sex chromosomes, and gender-specific behaviors likely contribute to these differences. The aging process is associated with changes in the composition and function of the immune system and these changes may occur at an accelerated rate in men as compared to women. Moreover, after the age of menopause, the incidence of chronic inflammatory disease in women approaches or exceeds that observed in males. At the same time, the incidence of autoimmunity in post-menopausal women is decreased or equivalent to the rates observed in similarly-aged men. Additional studies addressing the influence of sex on the pathogenesis of chronic and autoimmune diseases in the aged are warranted.

Effects of lasofoxifene and bazedoxifene on B cell development and function

The third generation selective estrogen receptor modulators lasofoxifene (las) and bazedoxifene (bza) are indicated for treatment of postmenopausal osteoporosis. 17β-Estradiol (E2) and the second generation SERM raloxifene (ral) have major effects on the immune system, particularly on B cells. Treatment with E2 or ral inhibits B lymphopoiesis and treatment with E2, but not ral, stimulates antibody production. The effects of las and bza on the immune system have not been studied. Therefore, the aim of this study was to investigate their role in B cell development, maturation, and function. C57BL/6 mice were sham-operated or ovariectomized (ovx) and treated with vehicle, E2, ral, las, or bza. All substances increased total bone mineral density in ovx mice, as measured by peripheral quantitative computed tomography. In uterus, bza alone lacked agonistic effect in ovx mice and even acted as an antagonist in sham mice. As expected, E2 decreased B cell numbers at all developmental stages from pre-BI cells (in bone marrow) to transitional 1 (T1) B cells (in spleen) and increased marginal zone (MZ) B cells as determined by flow cytometry. However, treatment with las or bza only decreased the last stages of bone marrow B cell development and splenic T1 B cells, but had no effect MZ B cells. E2 increased antibody-producing cells quantified by ELISPOT, but las or bza did not. In conclusion, las and bza differ from E2 by retaining normal number of cells at most B cell stages during B lymphopoiesis and maturation and by not increasing antibody-producing cells.

A dynamic network of estrogen receptors in murine lymphocytes: fine-tuning the immune response

The actual level of circulating estrogen (17β-estradiol, E2) has a serious impact on regulation of diverse immune cell functions, where their classical cytoplasmic receptors, ERα and ERβ, act as nuclear transcriptional regulators of multiple target genes. There is growing evidence, however, for rapid, "non-nuclear" regulatory effects of E2 on lymphocytes. Such effects are likely mediated by putative membrane-associated receptor(s) (mER), but the mechanistic details and the involved signaling pathways still remained largely unknown because of their complexity. Here, we show that in lymphocytes, mERs can signalize themselves, and upon ligation, they are able to coordinate translocation of other E2Rs to the PM. Our data firmly imply existence of a complex, dynamic network of at least seven ER forms in murine lymphocytes: cytoplasmic and membrane-linked forms of ERα, ERβ, or GPR30 and a mER that can receive extracellular E2 signals. The latter mERs are likely palmitoylated, as they are enriched in lipid-raft microdomains, and their E2 binding is also cholesterol dependent. The data also support that ligation of mERs can induce rapid regulatory signals to lymphocytes and then internalize and let the E2 liberate in lysosomes. In addition, they can dynamically control the cell-surface linkage of other cytoplasmic ERs. As demonstrated by the differential effects of mER or cytoplasmic ER ligation on the proliferation of activated T and B lymphocytes, such a dynamic E2R network can be considered as a tool to manage accommodation/fine-tuning of lymphocytes to rapidly changing hormone levels.

Oestrogen receptors β1 and βcx have divergent roles in breast cancer survival and lymph node metastasis

Background:

The expression of oestrogen receptor (ER) α characterises a subset of breast cancers associated with good response to endocrine therapy. However, the clinical significance of the second ER, ERβ1, and its splice variant ERβcx is still unclear.

Methods:

We here report an assessment of ERα, ERβ1 and ERβcx by immunohistochemistry using quantitative digital image analysis of 340 primary tumours and corresponding sentinel lymph nodes.

Results:

No differences were seen in ER levels in primary tumours vs lymph node metastases. ERβ1 and ERβcx were equally distributed among age groups and tumour histological grades. Loss of ERβ1 in the primary tumour was strongly associated with poor survival. Its prognostic impact was particularly evident in young patients and in high-grade tumours. The worst outcome was seen in the tumours lacking both ERα and ERβ1. ERβcx expression in the primary tumour correlated with a higher risk of lymph node metastasis, and with poor survival when expressed in sentinel node lymphocytes.

Conclusions:

Our study reveals highly significant although antagonising roles of ERβ1 and ERβcx in breast cancer. Consequently, we suggest that the histopathological assessment of ERβ1 is of value as a prognostic and potentially predictive biomarker.

Estrogen receptor α and β in the normal immune system and in lymphoid malignancies

Estrogens regulate various normal and pathophysiological processes including cancers. Cellular signaling by estrogens is mediated by estrogen receptor α (ERα) and β (ERβ), respectively. Binding of agonists to the ERs affects gene transcription. The main endogenous estrogen, 17β-estradiol (E2), binds to both ERα and ERβ with similar affinity. However, the ligand-binding pocket of ERα and ERβ are slightly different which has allowed the development of selective ER ligands. Importantly, while estrogens via ERα stimulate proliferation, signaling via ERβ inhibits proliferation and promotes apoptosis. In both normal and cancer cells the ERs are co-expressed with ER splice variants which may modify the transcriptional activity of the wild-type receptors. Estrogens have prominent effects on immune functions and both ERα and ERβ are expressed in immune cells and lymphoid malignancies. With regard to lymphoid malignancies, most show estrogen influence as several epidemiological studies of lymphoid cancers demonstrate gender differences in incidence and prognosis with males being more affected. In line with these findings, recent results generated by us have shown that ERβ selective agonists inhibit growth and induce apoptosis in human and murine lymphomas in vivo in xenograft experiments. This suggests that ERβ selective agonists in the future may be useful in the treatment of lymphomas.

A role for gut-associated lymphoid tissue in shaping the human B cell repertoire

Transitional 2 B cells home to gut-associated lymphoid tissue and present an activated phenotype in healthy subjects, but gut immune compartments are depleted in SLE.

We have tracked the fate of immature human B cells at a critical stage in their development when the mature B cell repertoire is shaped. We show that a major subset of bone marrow emigrant immature human B cells, the transitional 2 (T2) B cells, homes to gut-associated lymphoid tissue (GALT) and that most T2 B cells isolated from human GALT are activated. Activation in GALT is a previously unknown potential fate for immature human B cells. The process of maturation from immature transitional B cell through to mature naive B cell includes the removal of autoreactive cells from the developing repertoire, a process which is known to fail in systemic lupus erythematosus (SLE). We observe that immature B cells in SLE are poorly equipped to access the gut and that gut immune compartments are depleted in SLE. Thus, activation of immature B cells in GALT may function as a checkpoint that protects against autoimmunity. In healthy individuals, this pathway may be involved in generating the vast population of IgA plasma cells and also the enigmatic marginal zone B cell subset that is poorly understood in humans.

Mapping ERβ genomic binding sites reveals unique genomic features and identifies EBF1 as an ERβ interactor

Considerable effort by numerous laboratories has resulted in an improved understanding of estrogen and SERM action mediated by the two estrogen receptors, ERα and ERβ. However, many of the targets for ERβ in cell physiology remain elusive. Here, the C4-12/Flag.ERβ cell line which stably expressed Flag.ERβ is used to study ERβ genomic functions without ERα interference. Mapping ERβ binding sites in these cells reveals ERβ unique distribution and motif enrichment patterns. Accompanying our mapping results, nascent RNA profiling is performed on cells at the same treatment time. The combined results allow the identification of ERβ target genes. Gene ontology analysis reveals that ERβ targets are enriched in differentiation, development and apoptosis. Concurrently, E2 treatment suppresses proliferation in these cells. Within ERβ binding sites, while the most prevalent binding motif is the canonical ERE, motifs of known ER interactors are also enriched in ERβ binding sites. Moreover, among enriched binding motifs are those of GFI, REST and EBF1, which are unique to ERβ binding sites in these cells. Further characterization confirms the association between EBF1 and the estrogen receptors, which favors the N-terminal region of the receptor. Furthermore, EBF1 negatively regulates ERs at the protein level. In summary, by studying ERβ genomic functions in our cell model, we confirm the anti-proliferative role of ERβ and discover the novel cross talk of ERβ with EBF1 which has various implications in normal physiology.

Role of oestrogen receptors in bladder cancer development

Early studies documented the existence of sexual dimorphism in bladder cancer occurrence and progression, with a greater bladder cancer incidence in males than females. However, the progression of bladder cancer after diagnosis is much quicker in females than males. These findings can be explained by the effects of female hormones (predominantly oestrogens) and their binding receptors, including oestrogen receptor 1 (ESR1; also known as ERα), oestrogen receptor 2 (ESR2; also known as ERβ), and GPR30 protein on bladder cancer incidence and progression. Results from studies using various in vitro cell lines and in vivo mouse models demonstrate differential roles of oestrogen receptors in cancer initiation and progression. ERα suppresses bladder cancer initiation and invasion, whereas ERβ promotes bladder cancer initiation and progression. Mechanistic studies suggest that ERα and ERβ exert these effects via modulation of the AKT pathway and DNA replication complex, respectively. Targeting these signalling pathways--for example, with ERα agonists, ERβ antagonists, or selective oestrogen receptor modulators such as 4-[2-phenyl-5,7-bis(trifluoromethyl)pyrazolo[1,5-a]pyrimidin-3-yl]phenol (also known as PHTPP)--could lead to the development of new therapeutic approaches for controlling bladder cancer progression.

Gonadal steroids and humoral immunity

Humoral immune responses are sexually dimorphic. Female individuals generally exhibit more-robust antibody responses to vaccines and, in the clinical setting as well as in experimental models, are more likely than male individuals to produce autoreactive antibodies of pathogenic potential. A number of differences between the sexes might account for these observations, including differences in the dosage of specific X-chromosome and Y-chromosomal genes, increased exposure of female individuals to antigenic stimulation in childbearing, and differences in circulating concentrations of gonadal steroid hormones. The role of gonadal steroids in modulating such humoral immune responses has been studied for nearly a century, but advances in our knowledge of B-lymphocyte development and function, the mechanisms of immune tolerance, and the molecular basis of gonadal steroid hormone action are now yielding new understanding of the influence of gonadal steroid hormones on the humoral immune system. This Review examines how oestrogens and androgens modulate B-lymphocyte development and function, focusing on the areas of B-cell production in the bone marrow, the maintenance of immune tolerance for self antigens, and the processes of immunoglobulin heavy chain gene somatic hypermutation and class switch recombination during maturation of cells involved in humoral immune responses.

Estrogen receptor-alpha mediates Toll-like receptor-2 agonist-induced monocyte chemoattractant protein-1 production in mesangial cells

TLR2 agonists are well known for inducing NF-kB activation and inflammation, while estrogen receptor-alpha (ER-α) is a regulator of estrogen-mediated anti-inflammatory responses. In the present work, we determined the role of ER-α and phosphorylated ER-α in TLR2 agonist-induced MCP1 production in mesangial cells. We found that TLR2 agonists induced nuclear localization of phospho-ER-α (serine 118), and estrogen and TLR2 agonists both induced phosphorylation of ER-α at the serine 118 and 104/106 positions. Incubation of MRL/lpr mesangial cells with estrogen was found to attenuate TLR2 agonist-mediated MCP1 production. To determine the mode of action of ER-α/pER-α (serine-118), we used the ER-α inhibitor MPP and transfected mesangial cells with ER-α siRNA. ER-α inhibition was found to decrease MCP1 production in mesangial cells. Thus, ER-α/pER-α is an intermediate regulator for both TLR2-mediated MCP1 production during inflammation and estrogen-mediated anti-inflammatory signals in mesangial cells.

B cells as effectors and regulators of sex-biased arthritis

B cells have been implicated both with pathogenic as well as protective capabilities in induction and regulation of autoimmune diseases. Rheumatoid arthritis (RA) is an autoimmune disease that occurs more often in women than men. A significant role of B cells as antibody producing and antigen-presenting cells has been demonstrated in RA. Predisposition to RA is associated with the presence of certain HLA class II alleles that share sequences with DRB1*0401. To determine the role of HLA genes and B cells in vivo, we have generated transgenic mice carrying HLA genes, DRB1*0401 and DQ8, known to be associated with susceptibility to RA. Humanized mice can be induced to develop arthritis that mimics human disease in clinical, histopathological and sex bias. Effect of hormones on immune cells and their function has been described in humans and mice and has been suggested to be the major reason for female bias of autoimmune diseases. An immune response to an antigen requires presentation by HLA molecules thus suggesting a critical role of MHC in combination with sex hormones in susceptibility to develop rheumatoid arthritis. Based on our observations, we hypothesize that modulation of B cells by estrogen, presentation of modified antigens by DR4 and production of antigen-specific B cell modulating cytokines leads to autoreactivity in females. These data suggest that considering patient's sex may be crucial in selecting the optimal treatment strategy. Humanized mice expressing RA susceptible and resistant haplotype provide a means to investigate mechanism sex-bias of arthritis and future strategies for therapy.

A global DNA methylation and gene expression analysis of early human B-cell development reveals a demethylation signature and transcription factor network

The epigenetic changes during B-cell development relevant to both normal function and hematologic malignancy are incompletely understood. We examined DNA methylation and RNA expression status during early B-cell development by sorting multiple replicates of four separate stages of pre-B cells derived from normal human fetal bone marrow and applied high-dimension DNA methylation scanning and expression arrays. Features of promoter and gene body DNA methylation were strongly correlated with RNA expression in multipotent progenitors (MPPs) both in a static state and throughout differentiation. As MPPs commit to pre-B cells, a predominantly demethylating phenotype ensues, with 79% of the 2966 differentially methylated regions observed involving demethylation. Demethylation events were more often gene body associated rather than promoter associated; predominantly located outside of CpG islands; and closely associated with EBF1, E2F, PAX5 and other functional transcription factor (TF) sites related to B-cell development. Such demethylation events were accompanied by TF occupancy. After commitment, DNA methylation changes appeared to play a smaller role in B-cell development. We identified a distinct development-dependent demethylation signature which has gene expression regulatory properties for pre-B cells, and provide a catalog reference for the epigenetic changes that occur in pre-B-cell leukemia and other B-cell-related diseases.

Emerging roles for the interferon-inducible p200-family proteins in sex bias in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a complex autoimmune disease involving multiple organs. The disease is characterized by the production of pathogenic autoantibodies to DNA and certain nuclear antigens, chronic inflammation, and immune dysregulation. Genetic studies involving SLE patients and mouse models have indicated that multiple lupus susceptible genes contribute to the disease phenotype. Notably, the development of SLE in patients and in certain mouse models exhibits a strong sex bias. In addition, several lines of evidence indicates that activation of interferon-α (IFN-α) signaling in immune cells and alterations in the expression of certain immunomodulatory cytokines contribute to lupus pathogenesis. Studies have implicated factors, such as the X chromosomal gene dosage effect and the sex hormones, in gender bias in SLE. However, the molecular mechanisms remain unclear. Additionally, it remains unclear whether these factors influence the "IFN-signature," which is associated with SLE. In this regard, a mutually positive regulatory feedback loop between IFNs and estrogen receptor-α (ERα) has been identified in immune cells. Moreover, studies indicate that the expression of certain IFN-inducible p200-family proteins that act as innate immune sensors for cytosolic DNA is differentially regulated by sex hormones. In this review, we discuss how the modulation of the expression of the p200-family proteins in immune cells by sex hormones and IFNs contributes to sex bias in SLE. An improved understanding of the regulation and roles of the p200-family proteins in immune cells is critical to understand lupus pathogenesis as well as response (or the lack of it) to various therapies.

Subset size, activation threshold and distribution of autoreactive MZ and FO B cells do not differ in a sex-specific manner in the NZB/W F1 murine lupus model: an experimental mouse study

OBJECTIVES

Systemic lupus erythematosus (SLE) shows a strong sex bias, preferentially affecting females, and B cells are thought to play a pivotal role in its pathogenesis. Here, we compared the splenic B-cell compartments, their autoreactivity and activation threshold of female and male NZB/W F1, a murine lupus model reflecting the sex bias observed in patients with SLE.

METHODS

Autoantibody levels and the amount of autoantibody secreting cells were determined using ELISA and ELISPOT. Flow cytometry and immunofluorescence were applied to analyse the composition of the splenic B-cell pool. Purified follicular (FO) and marginal zone (MZ) B cells were stimulated and the frequency of autoreactive cells was determined. Finally, the proliferative response of FO and MZ B cells upon stimulation was assessed using CFSE dilution and [(3)H]-Thymidin incorporation.

RESULTS

Higher autoantibody titres were detected in female NZB/W F1 mice, which were mainly produced in the spleen. Analysing the composition of the splenic B-cell subsets, no differences were found prior to disease development. Autoreactive dsDNA-specific B cells were mostly found in the MZ compartment, while SmD1((83-119))-reactive cells were more evenly distributed. Equal frequencies of autoreactive B cells were found in female and malemice, and no difference in the response to polyclonal stimuli of the cells of both sexes was detected.

CONCLUSIONS

No differences in the composition or functionality of splenic B cells were observed that account for the different disease course in both sexes.