Estrogen induces a potent suppression of experimental autoimmune encephalomyelitis and collagen-induced arthritis in mice

Estrogen receptor alpha signaling in dendritic cells modulates autoimmune disease phenotype in mice

Estrogen is a disease-modifying factor in multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE) via estrogen receptor alpha (ERα). However, the mechanisms by which ERα signaling contributes to changes in disease pathogenesis have not been completely elucidated. Here, we demonstrate that ERα deletion in dendritic cells (DCs) of mice induces severe neurodegeneration in the central nervous system in a mouse EAE model and resistance to interferon beta (IFNβ), a first-line MS treatment. Estrogen synthesized by extragonadal sources is crucial for controlling disease phenotypes. Mechanistically, activated ERα directly interacts with TRAF3, a TLR4 downstream signaling molecule, to degrade TRAF3 via ubiquitination, resulting in reduced IRF3 nuclear translocation and transcription of membrane lymphotoxin (mLT) and IFNβ components. Diminished ERα signaling in DCs generates neurotoxic effector CD4+ T cells via mLT-lymphotoxin beta receptor (LTβR) signaling. Lymphotoxin beta receptor antagonist abolished EAE disease symptoms in the DC-specific ERα-deficient mice. These findings indicate that estrogen derived from extragonadal sources, such as lymph nodes, controls TRAF3-mediated cytokine production in DCs to modulate the EAE disease phenotype.

Effects of biological sex and pregnancy in experimental autoimmune encephalomyelitis: It's complicated

Experimental autoimmune encephalomyelitis (EAE) can be induced in many animal strains by inoculation with central nervous system antigens and adjuvant or by the passive transfer of lymphocytes reactive with these antigens and is widely used as an animal model for multiple sclerosis (MS). There are reports that female sex and pregnancy affect EAE. Here we review the effects of biological sex and the effects of pregnancy on the clinical features (including disease susceptibility) and pathophysiology of EAE. We also review reports of the possible mechanisms underlying these differences. These include sex-related differences in the immune system and in the central nervous system, the effects of hormones and the sex chromosomes and molecules unique to pregnancy. We also review sex differences in the response to factors that can modify the course of EAE. Our conclusion is that the effects of biological sex in EAE vary amongst animal models and should not be widely extrapolated. In EAE, it is therefore essential that studies looking at the effects of biological sex or pregnancy give full information about the model that is used (i.e. animal strain, sex, the inducing antigen, timing of EAE induction in relation to pregnancy, etc.). In addition, it would be preferable if more than one EAE model were used, to show if any observed effects are generalizable. This is clearly a field that requires further work. However, understanding of the mechanisms of sex differences could lead to greater understanding of EAE, and suggest possible therapies for MS.

Sex bias in lymphocytes: Implications for autoimmune diseases

Autoimmune diseases are characterized by a significant sex dimorphism, with women showing increased susceptibility to disease. This is, at least in part, due to sex-dependent differences in the immune system that are influenced by the complex interplay between sex hormones and sex chromosomes, with contribution from sociological factors, diet and gut microbiota. Sex differences are evident in the number and function of lymphocyte populations. Women mount a stronger pro-inflammatory response than males, with increased lymphocyte proliferation, activation and pro-inflammatory cytokine production, whereas men display expanded regulatory cell subsets. Ageing alters the immune landscape of men and women in differing ways, resulting in changes in autoimmune disease susceptibility. Here we review the current literature on sex differences in lymphocyte function, the factors that influence this, and the implications for autoimmune disease. We propose that improved understanding of sex bias in lymphocyte function can provide sex-specific tailoring of treatment strategies for better management of autoimmune diseases.

Sex and gender differences in autoimmune demyelinating CNS disorders: Multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD) and myelin-oligodendrocyte-glycoprotein antibody associated disorder (MOGAD)

Multiple sclerosis (MS), Neuromyelitis optica spectrum disorder (NMOSD) and Myelin-Oligodendrocyte-Glycoprotein antibody associated disorder (MOGAD) are demyelinating disorders of the central nervous system (CNS) of autoimmune origin. Here, we summarize general considerations on sex-specific differences in the immunopathogenesis and hormonal influences as well as key clinical and epidemiological elements. Gender-specific issues are widely neglected starting with the lacking separation of sex as a biological variable and gender comprising the sociocultural components. As for other autoimmune diseases, female preponderance is common in MS and NMOSD. However, sex distribution in MOGAD seems equal. As in MS, immunotherapy in NMOSD and MOGAD is crucial to prevent further disease activity. Therefore, we assessed data on sex differences of the currently licensed disease-modifying treatments for efficacy and safety. This topic seems widely neglected with only fragmented information resulting from post-hoc analyses of clinical trials or real-world post-marketing studies afflicted with lacking power and/or inherent sources of bias. In summary, biological hypotheses of sex differences including genetic factors, the constitution of the immune system and hormonal influences are based upon human and preclinical data, especially for the paradigmatic disease of MS whereas specific data for NMOSD and MOGAD are widely lacking. Epidemiological and clinical differences between men and women are well described for MS and to some extent for NMOSD, yet, with remaining contradictory findings. MOGAD needs further detailed investigation. Sex-specific analyses of safety and efficacy of long-term immunotherapies need to be addressed in future studies designed and powered to answer the pressing questions and to optimize and individualize treatment.

Modulatory role of prenatal alcohol exposure and adolescent stress on the response to arthritis challenge in adult female rats

Background

There are known environmental risk factors associated with rheumatoid arthritis; however, less is known regarding how the prenatal environment impacts later-life risk for rheumatoid arthritis. Based on preliminary clinical data suggesting that individuals with fetal alcohol spectrum disorder (FASD) are at higher risk for autoimmune disorders, this study investigated the modulatory impact of prenatal alcohol exposure (PAE) on the inflammatory disease profile in an adjuvant-induced arthritis rat model.

Methods

Pregnant rats received liquid ethanol or control diet throughout gestation. To model the increased exposure to stressors often experienced by individuals with FASD, adolescent offspring were exposed to chronic mild stress (CMS) or remained undisturbed. In adulthood, experimental arthritis was initiated and rats terminated either at the peak or following resolution from inflammation to assess endocrine, immune, and histopathological outcomes.

Findings

PAE rats had an increased incidence and severity of, and impaired recovery from, arthritis. Increased joint damage was observed in PAE animals, even in the face of apparent recovery from the clinical signs of arthritis, while it appeared that oestradiol may have a protective role. Moreover, with the combination of PAE and adolescent stress, increased macrophage density was detected in the synovium of PAE but not control rats.

Interpretation

These findings demonstrate that PAE alters the severity and course of arthritis, highlighting the potential immunomodulatory impact of adverse prenatal exposures. In particular, these data have implications for understanding preliminary data that suggest a heightened propensity for autoimmune disorders in individuals with FASD.

Recipient sex and estradiol levels affect transplant outcomes in an age-specific fashion

Sex-specific influences have been shown for a variety of diseases. Whether donor or recipient sex and sex hormone levels impact alloimmune responses remains unclear. In unifactorial and multifactorial analyses of more than 400 000 SRTR listed kidney transplant patients, we found that younger female recipients had an inferior death-censored graft survival that was independent of donor sex. In contrast, graft survival was superior in older female recipients, suggesting the impact of recipient sex hormones over chromosomal sex mismatches. Those clinical changes were delineated in experimental skin and heart transplant models showing a prolongation of graft survival in ovariectomized young female recipients. In contrast, graft survival was comparable in ovariectomized and naïve old female recipients. Young ovariectomized mice showed reduced amounts and a compromised T cell proliferation. Deprivation of female hormones dampened the production of interferon (IFN)-γ and interleukin (IL)-17+ by CD4+ T cells while augmenting systemic counts of Tregs. Increasing estradiol concentrations in vitro promoted the switch of naïve CD4+ T cells into Th1 cells; high physiological estradiol concentrations dampening Th1 responses, promoted Tregs, and prolonged graft survival. Thus, clinical observations demonstrate age-specific graft survival patterns in female recipients. Estrogen levels, in turn, impact the fate of T cell subsets, providing relevant and novel information on age- and sex-specific alloimmunity.

Sex Differences in the Immune System Become Evident in the Perinatal Period in the Four Core Genotypes Mouse

We have used the four core genotypes (FCG) mouse model, which allows a distinction between effects of gonadal secretions and chromosomal complement, to determine when sex differences in the immune system first appear and what influences their development. Using splenic T cell number as a measure that could be applied to neonates with as yet immature immune responses, we found no differences among the four genotypes at postnatal day 1, but by day 7, clear sex differences were observed. These sex differences were unexpectedly independent of chromosomal complement and similar in degree to gonadectomized FCG adults: both neonatal and gonadectomized adult females (XX and XY) showed 2-fold the number of CD4+ and 7-fold the number of CD8+ T cells versus their male (XX and XY) counterparts. Appearance of this long-lived sex difference between days 1 and 7 suggested a role for the male-specific perinatal surge of testicular testosterone. Interference with the testosterone surge significantly de-masculinized the male CD4+, but not CD8+ splenic profile. Treatment of neonates demonstrated elevated testosterone limited mature cell egress from the thymus, whereas estradiol reduced splenic T cell seeding in females. Neonatal male splenic epithelium/stroma expressed aromatase mRNA, suggesting capacity for splenic conversion of perinatal testosterone into estradiol in males, which, similar to administration of estradiol in females, would result in reduced splenic T cell seeding. These sex steroid effects affected both CD4+ and CD8+ cells and yet interference with the testosterone surge only significantly de-masculinized the splenic content of CD4+ cells. For CD8+ cells, male cells in the thymus were also found to express one third the density of sphingosine-1-phosphate thymic egress receptors per cell compared to female, a male characteristic most likely an indirect result of Sry expression. Interestingly, the data also support a previously unrecognized role for non-gonadal estradiol in the promotion of intra-thymic cell proliferation in neonates of both sexes. Microarray analysis suggested the thymic epithelium/stroma as the source of this hormone. We conclude that some immune sex differences appear long before puberty and more than one mechanism contributes to differential numbers and distribution of T cells.

Pregnancy-Induced Changes in microRNA Expression in Multiple Sclerosis

Pregnancy affects the disease course in multiple sclerosis (MS), particularly in the third trimester, where the relapse rate is reduced by as much as two thirds. This study aimed at identifying changes in microRNA (miRNA) and immune cell phenotypes in pregnant MS patients. Discovery and validation studies to detect differentially expressed miRNAs were performed with quantitative real-time PCR on peripheral blood mononuclear cells (PBMC). Flow cytometry analysis was performed on PBMC stained with antibodies directed against surface markers of antigen presenting cells (APCs), NK-cells, NKT cells, CD4+ and CD8+ T cells and subsets of these cell types, including PDL1 and PDL2 expressing subsets. RNA was extracted from whole blood, monocytes, and NK-cells to investigate expression and correlation between regulated miRNAs and mRNAs. In total, 15 miRNAs were validated to be differentially expressed between third trimester pregnant and postpartum MS patients (Benjamini-Hochberg false discovery rate from p = 0.03–0.00004). Of these, 12 miRNAs were downregulated in pregnancy and 6 of the 15 miRNAs were altered by more than ±2-fold (+2.99- to -6.38-fold). Pregnant MS patients had a highly significant increase in the percentage of monocytes and a decrease of NK-cells and myeloid dendritic cells compared to non-pregnant MS patients. We confirm previous reports of a relative increase in CD56-bright NK-cells and a decrease in CD56-dim NK-cells in third trimester of pregnancy and report an increase in non-committed follicular helper cells. PDL1 and PDL2 expression was increased in pregnant patients together with IL10. Also, in monocytes IL10, PDL1, and PDL2 were upregulated whereas miR-1, miR-20a, miR-28, miR-95, miR-146a, miR-335, and miR-625 were downregulated between pregnant and untreated MS patients. IL10, PDL1, and PDL2 were predicted targets of MS pregnancy-changed miRNAs, further supported by their negative correlations. Additionally, previously identified pregnancy-regulated mRNAs were identified as predicted targets of the miRNAs. PDL1 and PDL2 bind PD-1 expressed on T cells with an inhibitory effect on T-cell proliferation and increase in IL10 production. These results indicate that some of the effects behind the disease-ameliorating third trimester of pregnancy might be caused by changed expression of miRNAs and immunoregulatory molecules in monocytes.

The role of sex hormones in women with multiple sclerosis: From puberty to assisted reproductive techniques

BACKGROUND

Multiple Sclerosis is a multifactorial chronic autoimmune disease, affecting predominantly females in the fertile age. Sex hormones changes during a woman's life, from puberty to menopause, including pregnancy and puerperium, may influence the onset and course of Multiple Sclerosis. The effect of estrogen levels on immune, clinical and radiological aspects of Multiple Sclerosis, also stimulated investigation on the effect of sexual hormones therapies, such as oral contraceptives and assisted reproductive technique, on the Multiple Sclerosis course.

SEARCH STRATEGY AND SELECTION CRITERIA

A literature search for original articles and reviews was conducted in the databases, including PubMed, Scopus, and ClinicalTrials.gov of the U.S. National Library of Medicine site from 1988 to 2020.

RESULTS AND CONCLUSION

This review reports the effects of the physiological and iatrogenic hormonal changes either on immune or clinical or paraclinical features in the different life stages of women affected by Multiple Sclerosis.

Estriol in regulation of cell-mediated immune reactions in multiple sclerosis

The effect of pregnancy hormone estriol (E₃) on innate and adaptive immunity cells functions in patients with multiple sclerosis (MS) in comparison with healthy donors (HD) was studied. E₃ inhibited phagocytic activity of neutrophils and enhanced monocytes IDO activity. Treg percentage increased and number of Th17 and iNKT cells decreased under E₃ influence. At the same time, E₃ stimulated production of IL-10 and inhibited secretion of IL-17. The hormonal effects were realized on the cells of both HD and MS patients. Thus, the MS amelioration during pregnancy may be related to E₃ influence.

The sex-specific patterns of changes in hypothalamic-pituitary-gonadal axis during experimental autoimmune encephalomyelitis

Multiple sclerosis develops during reproductive years in a sex-specific manner. Various neuroendocrine changes have been described in this inflammatory, demyelinating, and debilitating disease. We here aimed to determine the extent and sex specificity of alterations in the hypothalamic-pituitary-gonadal axis in the rat model of multiple sclerosis named experimental autoimmune encephalomyelitis. During the disease course, the hypothalamic tissue showed transient upregulation of inflammatory marker genes Gfap, Cd68, Ccl2, and Il1b in both sexes, but accompanied by sex-specific downregulation of Kiss1 (in females only) and Gnrh1 (in males only) expression. In females, the expression of gonadotrope-specific genes Lhb, Cga, and Gnrhr was also inhibited, accompanied by decreased basal but not stimulated serum luteinizing hormone levels and a transient arrest of the estrous cycle. In contrast, Fshb expression and serum progesterone levels were transiently elevated, findings consistent with the maintenance of the corpora lutea, and elevated immunohistochemical labeling of ovarian StAR, a rate limiting protein in steroidogenic pathway. In males, downregulation of Gnrhr expression and basal and stimulated serum luteinizing hormone and testosterone levels were accompanied by inhibited testicular StAR protein expression. We propose that inflammation of hypothalamic tissue downregulates Kiss1 and Gnrh1 expression in females and males, respectively, leading to sex-specific changes downstream the axis.

Pregnancy, postpartum and parity: Resilience and vulnerability in brain health and disease

Risk and resilience in brain health and disease can be influenced by a variety of factors. While there is a growing appreciation to consider sex as one of these factors, far less attention has been paid to sex-specific variables that may differentially impact females such as pregnancy and reproductive history. In this review, we focus on nervous system disorders which show a female bias and for which there is data from basic research and clinical studies pointing to modification in disease risk and progression during pregnancy, postpartum and/or as a result of parity: multiple sclerosis (MS), depression, stroke, and Alzheimer's disease (AD). In doing so, we join others (Shors, 2016; Galea et al., 2018a) in aiming to illustrate the importance of looking beyond sex in neuroscience research.

Neuroimmunologic disorders in pregnancy

Pregnancy influences the course of neuroimmunologic conditions, which include multiple sclerosis (MS), neuromyelitis optica spectrum disorder, and autoimmune encephalitis. The outcomes differ significantly for each disorder, reflecting the impact of hormonal changes, T-cell subsets, and placental factors on disease pathogenesis. In recent years, numerous data have emerged regarding MS activity throughout pregnancy and postpartum. Historically, the misconception that pregnancy worsens MS outcomes led patients to abstain from childbearing. Now, more women with these disorders, empowered by up-to-date information and better baseline disease control, are choosing to conceive. Nevertheless, the management of MS and related disorders in the pregnancy and postpartum period is complicated and requires a nuanced approach. Since standardized treatment guidelines around pregnancy are currently lacking, neurologists, together with obstetricians, must engage patients in a shared decision-making process that weighs the benefits to the mother and risks to the fetus. This chapter outlines the pathophysiology of neuroimmunologic disorders during pregnancy and postpartum, the impact of these diseases on childbearing, including fertility, pregnancy, delivery, and peurperium, as well as existing recommendations for treatment.

Comparative analysis of gene expression profiles in children with type 1 diabetes mellitus

Type 1 diabetes (T1D) is an autoimmune disease that is typically diagnosed in children. The aim of the present study was to identify potential genes involved in the pathogenesis of childhood T1D. Two datasets of mRNA expression in children with T1D were obtained from the Gene Expression Omnibus (GEO). Differentially expressed genes (DEGs) in children with T1D were identified. Functional analysis was performed and a protein‑protein interaction (PPI) network was constructed, as was a transcription factor (TF)‑target network. The expression of selected DEGs was further assessed using reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) analysis. Electronic validation and diagnostic value analysis of the identified DEGs [cytokine inducible SH2 containing protein (CISH), SR‑related CTD associated factor 11 (SCAF11), estrogen receptor 1 (ESR1), Rho GTPase activating protein 25 (ARHGAP25), major histocompatibility complex, class II, DR β4 (HLA‑DRB4) and interleukin 23 subunit α (IL23A)] was performed in the GEO dataset. Compared with the normal control group, a total of 1,467 DEGs with P<0.05 were identified in children with T1D. CISH and SCAF11 were determined to be the most up‑ and downregulated genes, respectively. Heterogeneous nuclear ribonucleoprotein D (HNRNPD; degree=33), protein kinase AMP‑activated catalytic subunit α1 (PRKAA1; degree=11), integrin subunit α4 (ITGA4; degree=8) and ESR1 (degree=8) were identified in the PPI network as high‑degree genes. ARHGAP25 (degree=12), HNRNPD (degree=10), HLA‑DRB4 (degree=10) and IL23A (degree=9) were high‑degree genes identified in the TF‑target network. RT‑qPCR revealed that the expression of HNRNPD, PRKAA1, ITGA4 and transporter 2, ATP binding cassette subfamily B member was consistent with the results of the integrated analysis. Furthermore, the results of the electronic validation were consistent with the bioinformatics analysis. SCAF11, CISH and ARHGAP25 were identified to possess value as potential diagnostic markers for children with T1D. In conclusion, identifying DEGs in children with T1D may contribute to our understanding of its pathogenesis, and such DEGs may be used as diagnostic biomarkers for children with T1D.

Impact of sex hormones on immune function and multiple sclerosis development

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) affecting young people and leading to demyelination and neurodegeneration. The disease is clearly more common in women, in whom incidence has been rising. Gender differences include: earlier disease onset and more frequent relapses in women; and faster progression and worse outcomes in men. Hormone-related physiological conditions in women such as puberty, pregnancy, puerperium, and menopause also exert significant influence both on disease prevalence as well as on outcomes. Hormonal and/or genetic factors are therefore believed to be involved in regulating the course of disease. In this review, we discuss clinical evidence for the impact of sex hormones (estrogens, progesterone, prolactin, and testosterone) on MS and attempt to elucidate the hormonal and immunological mechanisms potentially underlying these changes. We also review current knowledge on the relationship between sex hormones and resident CNS cells and provide new insights in the context of MS. Understanding these molecular mechanisms may contribute to the development of new and safer treatments for both men and women.

A case for gender-based approach to multiple sclerosis therapeutics

Despite established sex differences in multiple sclerosis (MS) risk and course, sex-specific efficacy and toxicity of existing MS therapies, and possible sex-specific therapeutic approaches, remain underexplored. We systematically reviewed published sex differences from Phase III pivotal trials for FDA or EMA-approved MS disease modifying therapies (DMTs), along with additional information from pharmaceutical companies, for pre-specified or post-hoc baseline characteristics, efficacy and safety outcomes by sex, and sex-specific concerns. Then, we reviewed trials testing hormonal therapies in MS. None of the Phase III clinical trials performed baseline sex-specific analyses or were powered to evaluated DMTs in menopausal/older populations. Some recent trials performed pre-specified or post-hoc stratification of outcomes by sex. Sex-specific hormonal intervention trials were limited. Adequately powered, pre-specified analyses accounting for baseline sex and age are required to maximize safety and efficacy in specific patient populations.

Estriol: emerging clinical benefits

OBJECTIVE

Estriol is the main estrogen in pregnancy, but has received less attention outside gestation. It is well known that pregnancy has an immunosuppressive effect on many autoimmune diseases such as multiple sclerosis, psoriasis, thyroiditis, uveitis, and rheumatoid arthritis. Emerging evidence indicates that estriol has potential immunomodulatory benefits for many disease states including autoimmune, inflammatory, and neurodegenerative conditions. In this review, we discuss emerging roles for estriol in the treatment of menopausal symptoms, osteoporosis, cancer, hyperlipidemia, vascular disease, and multiple sclerosis. Estriol appears to offer a potentially cost-effective approach to a variety of conditions and may offer a wide range of health benefits.

METHODS

We reviewed the English language MEDLINE literature with estriol in the title with emphasis on publications including nonpregnant females between January 1974 and August 2016. Approximately 393 such articles were considered and 72 articles have been referenced in this review.

RESULTS

Estriol offers considerable benefits for postmenopausal women with reduced risks that are normally associated with traditional hormone therapies. These benefits include improved control of menopausal symptoms and better urogenital health. Moreover, the immunomodulatory role of estriol in reducing proinflammatory cytokines may be an important new therapeutic option for chronic autoimmune and neurodegenerative illnesses. Since it is a relatively weak estrogen, there is potential for use in men for conditions such as multiple sclerosis.

CONCLUSIONS

We conclude transvaginal estriol potentially offers a suitable physiologic delivery and cost-effective alternative to currently available estrogen regimens in selected patients. Additional studies on mode of delivery, safety, and efficacy merit further investigation.

The importance of studying sex differences in disease: The example of multiple sclerosis

To date, scientific research has often focused on one sex, with assumptions that study of the other sex would yield similar results. However, many diseases affect males and females differently. The sex of a patient can affect the risk for both disease susceptibility and progression. Such differences can be brought to the laboratory bench to be investigated, potentially bringing new treatments back to the clinic. This method of research, known as a "bedside to bench to bedside" approach, has been applied to studying sex differences in multiple sclerosis (MS). Females have greater susceptibly to MS, while males have worse disease progression. These two characteristics of the disease are influenced by the immune system and the nervous system, respectively. Thus, sex differences in each system must be studied. Personalized medicine has been at the forefront of research recently, and studying sex differences in disease fits with this initiative. This review will discuss the known sex differences in MS and highlight how investigating them can lead to new insights and potential treatments for both men and women. © 2016 Wiley Periodicals, Inc.

Pregnancy: Effect on Multiple Sclerosis, Treatment Considerations, and Breastfeeding

Multiple sclerosis (MS) commonly affects women in childbearing years making pregnancy issues important for patients with MS and their families. Pregnancy is a naturally occurring disease modifier of MS associated with a 70% reduction in relapse rates in the third trimester. This relapse rate reduction during the last trimester is roughly equal to the most effective disease-modifying treatments for MS. Given this efficacy, various pregnancy factors have been tested to determine which play a part in pregnancy's protection, and some have been translated to completed and ongoing phase II clinical trials. In contrast to protective effects during pregnancy, the postpartum period entails increased relapse risk, which may be due to either abrupt removal of protective pregnancy factors after delivery or to unique deleterious factors inherent to the postpartum period. The effect of breastfeeding on MS remains unclear. The best predictor for whether a patient will have a postpartum relapse is the incidence of her having active relapsing MS prior to pregnancy. The medical management of MS during pregnancy and the postpartum period is challenging given the risks of medication exposure to the fetus in utero and to the infant through breast milk. This review will focus on clinical aspects of pregnancy, including the effects of pregnancy on MS disease activity, as well as the medical management of MS during pregnancy and postpartum.

The role of the prolactin/vasoinhibin axis in rheumatoid arthritis: an integrative overview

Rheumatoid arthritis (RA) is a chronic, autoimmune, inflammatory disease destroying articular cartilage and bone. The female preponderance and the influence of reproductive states in RA have long linked this disease to sexually dimorphic, reproductive hormones such as prolactin (PRL). PRL has immune-enhancing properties and increases in the circulation of some patients with RA. However, PRL also suppresses the immune system, stimulates the formation and survival of joint tissues, acquires antiangiogenic properties upon its cleavage to vasoinhibins, and protects against joint destruction and inflammation in the adjuvant-induced model of RA. This review addresses risk factors for RA linked to PRL, the effects of PRL and vasoinhibins on joint tissues, blood vessels, and immune cells, and the clinical and experimental data associating PRL with RA. This information provides important insights into the pathophysiology of RA and highlights protective actions of the PRL/vasoinhibin axis that could lead to therapeutic benefits.

A putative mechanism on remission of multiple sclerosis during pregnancy: estrogen-induced indoleamine 2,3-dioxygenase by dendritic cells

The basis for the reduced relapse rate of multiple sclerosis (MS) during pregnancy remains unexplained but, if defined, could create novel treatment options. Estrogen constitutes one candidate molecule, but the mechanism by which estrogen may affect MS during pregnancy is unclear. In this study, we used monocyte-derived dendritic cells (DCs) from MS patients to explore the estrogen (17-b-estradiol)-related pathway of immune modulation. Estrogen induced the expression of indoleamine 2,3-dioxygenase (IDO) on DCs, limiting T-cell proliferation and both Th1 and Th2 cytokine production. The suppression of T-cell proliferation mediated by estrogenexposed DCs was partly abolished by the IDO-inhibitor, 1-methyl-dl-tryptophan, indicating that estrogen-exposed DCs induced IDO-dependent T-cell suppression. Our data support the hypothesis that the change in the clinical course of MS observed in pregnancy may be related to the estrogen DC-IDO axis, which could represent a novel target for MS therapy.

The influence of sex hormones on cytokines in multiple sclerosis and experimental autoimmune encephalomyelitis: a review

The female predominance of multiple sclerosis (MS) has suggested that hormonal differences between the sexes must confer some protective effect on males or enhance the susceptibility of females to this disease. There has been evidence that gonadal hormones can modulate the immune response regulated by antigen presenting cells and T cells. These cells control the immune response by the production of interacting pro- and anti-inflammatory cytokines. The first include the acute phase pro-inflammatory cytokines of the innate immune response as well as the T-helper 1 (Th1) cytokines, while the later contain the Th2 cytokines as well as the suppressor cytokines. There is some evidence that MS and experimental autoimmune encephalitis (EAE) are Th1 cell-mediated diseases. For this reason many studies have been done to influence the pro-inflammatory cytokine production of these Th1 cells in favour of an anti-inflammatory immune response as mediated by Th2 cells. However the role of the regulatory T cells in this context is not clearly understood. Here we review the studies concerning the role of sex hormones on the cytokine production in relation to the disease course of MS and EAE and in particular in the light of the recent revival of the regulatory T cells and their suppressive cytokines.

Gender-specific differences in PPARγ regulation of follicular helper T cell responses with estrogen

Peroxisome proliferator-activated receptor gamma (PPARγ), a master regulator of adipocyte differentiation, has recently been connected with effector T cells, though its role is still not clear. Here, we investigated the roles of PPARγ in follicular helper T (T_FH) cell responses regarding gender specificity. NP-OVA immunization in female but not male CD4-PPARγ^KO mice induced higher proportions of T_FH cells and germinal center (GC) B cells following immunization than were seen in wild type mice. Treatment with the PPARγ agonist pioglitazone significantly reduced T_FH cell responses in female mice while pioglitazone and estradiol (E2) co-treatment ameliorated T_FH cells and GC responses in male mice. E2 treatment significantly enhanced PPARγ expression in male T cells, while T cell activation in the estrus but not in the diestrus stage of the menstrual cycle of females was inhibited by pioglitazone, suggesting that an estrogen-sufficient environment is important for PPARγ-mediated T cell regulation. These results demonstrate gender-based differences in sensitivities of PPARγ in T_FH responses. These findings suggest that appropriate function of PPARγ is required in the regulation of female GC responses and that therapeutic strategies for autoimmune diseases using PPARγ agonists need to be tailored accordingly.

Nudging oligodendrocyte intrinsic signaling to remyelinate and repair: Estrogen receptor ligand effects

Demyelination in multiple sclerosis (MS) leads to significant, progressive axonal and neuronal degeneration. Currently existing immunosuppressive and immunomodulatory therapies alleviate MS symptoms and slow, but fail to prevent or reverse, disease progression. Restoration of damaged myelin sheath by replenishment of mature oligodendrocytes (OLs) should not only restore saltatory axon conduction, but also provide a major boost to axon survival. Our previous work has shown that therapeutic treatment with the modestly selective generic estrogen receptor (ER) β agonist diarylpropionitrile (DPN) confers functional neuroprotection in a chronic experimental autoimmune encephalomyelitis (EAE) mouse model of MS by stimulating endogenous remyelination. Recently, we found that the more potent, selective ERβ agonist indazole-chloride (Ind-Cl) improves clinical disease and motor performance. Importantly, electrophysiological measures revealed improved corpus callosal conduction and reduced axon refractoriness. This Ind-Cl treatment-induced functional remyelination was attributable to increased OL progenitor cell (OPC) and mature OL numbers. At the intracellular signaling level, transition of early to late OPCs requires ERK1/2 signaling, and transition of immature to mature OLs requires mTOR signaling; thus, the PI3K/Akt/mTOR pathway plays a major role in the late stages of OL differentiation and myelination. Indeed, therapeutic treatment of EAE mice with various ERβ agonists results in increased brain-derived neurotrophic factor (BDNF) and phosphorylated (p) Akt and p-mTOR levels. It is notable that while DPN's neuroprotective effects occur in the presence of peripheral and central inflammation, Ind-Cl is directly neuroprotective, as demonstrated by remyelination effects in the cuprizone-induced demyelination model, as well as immunomodulatory. Elucidating the mechanisms by which ER agonists and other directly remyelinating agents modulate endogenous OPC and OL regulatory signaling is critical to the development of effective remyelinating drugs. The discovery of signaling targets to induce functional remyelination will valuably contribute to the treatment of demyelinating neurological diseases, including MS, stroke, and traumatic brain and spinal cord injury.

Estrogens, inflammation and cognition

The effects of estrogens are pleiotropic, affecting multiple bodily systems. Changes from the body's natural fluctuating levels of estrogens, through surgical removal of the ovaries, natural menopause, or the administration of exogenous estrogens to menopausal women have been independently linked to an altered immune profile, and changes to cognitive processes. Here, we propose that inflammation may mediate the relationship between low levels of estrogens and cognitive decline. In order to determine what is known about this connection, we review the literature on the cognitive effects of decreased estrogens due to oophorectomy or natural menopause, decreased estrogens' role on inflammation--both peripherally and in the brain--and the relationship between inflammation and cognition. While this review demonstrates that much is unknown about the intersection between estrogens, cognition, inflammation, we propose that there is an important interaction between these literatures.

Selective oestrogen receptor modulators lasofoxifene and bazedoxifene inhibit joint inflammation and osteoporosis in ovariectomised mice with collagen-induced arthritis

OBJECTIVE

RA predominantly affects post-menopausal women and is strongly associated with development of generalised osteoporosis. To find treatments that target both joint manifestations and osteoporosis in RA is desirable. The third generation of selective oestrogen receptor modulators (SERMs) [lasofoxifene (LAS) and bazedoxifene (BZA)] are new treatment options for post-menopausal osteoporosis. The aim of this study was to investigate the effects of LAS and BZA on arthritic disease and inflammation-associated bone loss using CIA in mice.

METHODS

Female DBA/1 mice were ovariectomised and subjected to CIA as a model of post-menopausal RA. Mice received treatment with LAS, BZA, 17β-estradiol (E2) as reference or vehicle. Arthritis development was assessed and BMD was determined by peripheral quantitative CT of the femurs. Serologic markers of inflammation and cartilage destruction were analysed. Immune cells in lymph nodes were studied by flow cytometry.

RESULTS

LAS and BZA reduced the clinical severity of arthritis as well as the grade of histologic synovitis and erosions on cartilage and bone. Moreover, SERMs protected against generalised bone loss in CIA by increasing trabecular BMD. Both SERMs decreased serum marker of cartilage destruction and LAS reduced serum IL-6 levels. SERMs did not alter Th17 cells in lymph nodes as E2 did.

CONCLUSION

The anti-osteoporotic drugs LAS and BZA were found to be potent inhibitors of joint inflammation and bone destruction in experimental arthritis. This study provides new important knowledge regarding the treatment regimen of post-menopausal women with RA who suffer from increased risk for osteoporosis.

Estrogen anti-inflammatory activity on human monocytes is mediated through cross-talk between estrogen receptor ERα36 and GPR30/GPER1

Estrogens are known modulators of monocyte/macrophage functions; however, the underlying mechanism has not been clearly defined. Recently, a number of estrogen receptor molecules and splice variants were identified that exert different and sometimes opposing actions. We assessed the expression of estrogen receptors and explored their role in mediating estrogenic anti-inflammatory effects on human primary monocytes. We report that the only estrogen receptors expressed are estrogen receptor-α 36-kDa splice variant and G-protein coupled receptor 30/G-protein estrogen receptor 1, in a sex-independent manner. 17-β-Estradiol inhibits the LPS-induced IL-6 inflammatory response, resulting in inhibition of NF-κB transcriptional activity. This is achieved via a direct physical interaction of ligand-activated estrogen receptor-α 36-kDa splice variant with the p65 component of NF-κB in the nucleus. G-protein coupled receptor 30/G-protein estrogen receptor 1, which also physically interacts with estrogen receptor-α 36-kDa splice variant, acts a coregulator in this process, because its inhibition blocks the effect of estrogens on IL-6 expression. However, its activation does not mimic the effect of estrogens, on neither IL-6 nor NF-κB activity. Finally, we show that the estrogen receptor profile observed in monocytes is not modified during their differentiation to macrophages or dendritic cells in vitro and is shared in vivo by macrophages present in atherosclerotic plaques. These results position estrogen receptor-α 36-kDa splice variant and G-protein coupled receptor 30 as important players and potential therapeutic targets in monocyte/macrophage-dependent inflammatory processes.

The immunologic effects of estrogen on psoriasis: A comprehensive review

BACKGROUND

Immunological changes in pregnancy are associated with improvements in some pre-existing immune-mediated skin diseases. Estrogen has been hypothesized to contribute to these changes by creating a shift from Th1 and Th17 to Th2 immunity. As this hypothesis would predict, psoriasis (a primarily Th17 mediated immune disease) tends to improve during pregnancy. However, the precise mechanism by which estrogen induces immunological change in psoriasis remains poorly understood.

OBJECTIVE

To summarize the immunologic effects of estrogen as they relate to psoriasis during pregnancy.

METHODS

We performed an English-language PubMed search of articles from September 2004 to September 2014 combining the key terms "psoriasis," "estrogen," "autoimmune disease," and "pregnancy."

RESULTS

Estrogen appears to up-regulate Th2 cytokines and down-regulate Th1 and Th17 cytokines. This shift was initially observed in murine systems, which showed decreased mixed lymphocyte reactions of splenocytes and increased antibody production during pregnancy. Antigen stimulated splenocytes produced fewer Th1 cytokines and more Th2 cytokines in pregnant mice. IL17 producing T cells were significantly decreased in healthy pregnancies compared to non-pregnant controls.

LIMITATIONS

This review is limited by the paucity of studies evaluating immunological changes of psoriasis in pregnancy among human subjects.

CONCLUSIONS

Increased estrogen production in pregnancy is associated with decreased Th1 and Th17 cytokine production. While estrogen may be responsible for some of these immune shifts resulting in disease improvement, there remains no definitive evidence to prove the hypothesis that estrogen is responsible for such improvement.

Pharmacotherapy with 17β-estradiol and progesterone prevents development of mouse experimental autoimmune encephalomyelitis

BACKGROUND

Pregnant women with multiple sclerosis (MS) show disease remission in the third trimester concomitant with high circulating levels of sex steroids. Rodent experimental autoimmune encephalomyelitis (EAE) is an accepted model for MS. Previous studies have shown that monotherapy with estrogens or progesterone exert beneficial effects on EAE. The aim of the present study was to determine if estrogen and progesterone cotherapy of C57BL/6 female mice provided substantial protection from EAE.

METHODS

A group of mice received single pellets of progesterone (100 mg) and 17 β-estradiol (2.5 mg) subcutaneously 1 week before EAE induction, whereas another group were untreated before EAE induction. On day 16 we compared the two EAE groups and control mice in terms of clinical scores, spinal cord demyelination, expression of myelin basic protein and proteolipid protein, macrophage cell infiltration, neuronal expression of brain-derived neurotrophic factor mRNA and protein, and the number of glial fribrillary acidic protein (GFAP)-immunopositive astrocytes.

RESULTS

Clinical signs of EAE were substantially attenuated by estrogen and progesterone treatment. Steroid cotherapy prevented spinal cord demyelination, infiltration of inflammatory cells and GFAP+ astrogliocytes to a great extent. In motoneurons, expression of BDNF mRNA and protein was highly stimulated, indicating concomitant beneficial effects of the steroid on neuronal and glial cells.

CONCLUSIONS

Cotherapy with estrogen and progesterone inhibits the development of major neurochemical abnormalities and clinical signs of EAE. We suggest that a combination of neuroprotective, promyelinating and immuno-suppressive mechanisms are involved in these beneficial effects.

Role of the immunogenic and tolerogenic subsets of dendritic cells in multiple sclerosis

Multiple sclerosis (MS) is an immune-mediated disorder in the central nervous system (CNS) characterized by inflammation and demyelination as well as axonal and neuronal degeneration. So far effective therapies to reverse the disease are still lacking; most therapeutic drugs can only ameliorate the symptoms or reduce the frequency of relapse. Dendritic cells (DCs) are professional antigen presenting cells (APCs) that are key players in both mediating immune responses and inducing immune tolerance. Increasing evidence indicates that DCs contribute to the pathogenesis of MS and might provide an avenue for therapeutic intervention. Here, we summarize the immunogenic and tolerogenic roles of DCs in MS and review medicinal drugs that may affect functions of DCs and have been applied in clinic for MS treatment. We also describe potential therapeutic molecules that can target DCs by inducing anti-inflammatory cytokines and inhibiting proinflammatory cytokines in MS.

Sex-Based Differences in Multiple Sclerosis (Part I): Biology of Disease Incidence

Multiple sclerosis (MS) is a chronic autoimmune demyelinating disease that leads to neuron damage and progressive disability. One major feature of multiple sclerosis (MS) is that it affects women three times more often than men. In this chapter, we overview the evidence that the autoimmune component of MS, which predominates in the early stages of this disease, is more robust in women than in men and undergoes a sharp increase with the onset of puberty. In addition, we discuss the common rodent models of MS that have been used to study the sex-based differences in the development of central nervous system (CNS) autoimmunity. We then address the biological underpinnings of this enhanced MS risk in women by first reviewing the autoimmune mechanisms that are thought to lead to the initiation of this disease and then honing in on how these mechanisms differ between the sexes. Finally, we review what is known about the hormonal and genetic basis of these sex differences in CNS autoimmunity.

Estriol strongly inhibits DNCB-induced contact dermatitis: role of antigen-specific antibodies in pathogenesis

The endogenous estrogens are important modulators of the immune system and its functions. However, their effects are rather complex and many aspects have not been studied. In this study, we used the 1-chloro-2,4-dinitrobenzene (DNCB)-induced contact dermatitis as a disease model and investigated the effect of estriol (E3), along with two other estrogens, 17β-estradiol and estrone, on the pathogenesis of contact hypersensitivity. A series of parameters, such as ear swelling, skin inflammation, antigen-specific immunoglobulins, and lymphocyte compositions in peripheral lymphoid organs, were evaluated in mice following development of contact dermatitis. We found that administration of all three estrogens elicited strong inhibition of DNCB-induced dermatitis, while E3 exerted the strongest suppressive effect. Administration of E3 alleviated dermatitis, and this effect was accompanied by decreases in serum DNCB-specific immunoglobulins, such as IgA, IgG1, IgG2a, and IgG2b. Besides, treatment with E3 reduced B cell population, especially IgG-producing cells in the peripheral lymphoid organs following the induction of dermatitis. These observations consistently suggest that the antibody (Ab)-mediated humoral immune reactions play a critical role in the pathogenesis of DNCB-induced contact dermatitis. The results from this study demonstrate, for the first time, that estrogen administration has a strong suppressive effect on the pathogenesis of contact dermatitis. These findings offer important insights concerning the pathogenic role of antigen-specific Abs in contact dermatitis and the treatment of chemical-induced, Ab-mediated skin hypersensitivity reactions in humans.

Multiple sclerosis at menopause: Potential neuroprotective effects of estrogen

Multiple sclerosis (MS) is an autoimmune demyelinating and neurodegenerative condition of the central nervous system that preferentially afflicts women more than men. Low estrogen states such as menopause and the postpartum period favor exacerbations of multiple sclerosis in women with the disease. Existing and emerging evidence suggests a role for estrogen in the alleviation of symptoms and reversal of pathology associated with MS. While clinical evidence is sparse regarding the benefit of estrogen therapy for women at risk for MS exacerbations, scientific data demonstrates that estrogen potentiates numerous neuroprotective effects on the central nervous system (CNS). Estrogens play a wide range of roles involved in MS disease pathophysiology, including increasing antiinflammatory cytokines, decreasing demyelination, and enhancing oxidative and energy producing processes in CNS cells.

Future treatment approaches to multiple sclerosis

The modern treatment era for multiple sclerosis (MS) began in 1993 with the approval of the first disease-modifying agent. Since then the field has greatly expanded, with 10 therapies currently approved to treat MS. These treatments are effective to reduce relapses and changes on MRI, and slow disability. However, despite these medications some patients continue to have exacerbations, accumulate disability, and develop progressive disease due to partial effectiveness. New molecules with novel mechanisms of action and targets are being explored. Hopefully these agents will yield even greater efficacy without significant safety concerns. As more aggressive therapies are available to treat MS, the goals and expectations of treatment are also likely to change. Some of the emerging therapies, including alemtuzumab, daclizumab, rituximab, ocrelizumab, laquinimod, estriol, 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins), vitamin D, and stem cell transplantation, will be discussed in this chapter. In the future, therapies with different mechanisms may be combined, but this will need to be evaluated in clinical trials. Neuroprotection and repair definitely warrant further study. The future of MS treatment is very exciting, especially as our armamentarium expands.

Gender differences in autoimmune disease

Autoimmune diseases are a range of diseases in which the immune response to self-antigens results in damage or dysfunction of tissues. Autoimmune diseases can be systemic or can affect specific organs or body systems. For most autoimmune diseases there is a clear sex difference in prevalence, whereby females are generally more frequently affected than males. In this review, we consider gender differences in systemic and organ-specific autoimmune diseases, and we summarize human data that outlines the prevalence of common autoimmune diseases specific to adult males and females in countries commonly surveyed. We discuss possible mechanisms for sex specific differences including gender differences in immune response and organ vulnerability, reproductive capacity including pregnancy, sex hormones, genetic predisposition, parental inheritance, and epigenetics. Evidence demonstrates that gender has a significant influence on the development of autoimmune disease. Thus, considerations of gender should be at the forefront of all studies that attempt to define mechanisms that underpin autoimmune disease.

XY sex chromosome complement, compared with XX, in the CNS confers greater neurodegeneration during experimental autoimmune encephalomyelitis

Women are more susceptible to multiple sclerosis (MS) and have more robust immune responses than men. However, men with MS tend to demonstrate a more progressive disease course than women, suggesting a disconnect between the severity of an immune attack and the CNS response to a given immune attack. We have previously shown in an MS model, experimental autoimmune encephalomyelitis, that autoantigen-sensitized XX lymph node cells, compared with XY, are more encephalitogenic. These studies demonstrated an effect of sex chromosomes in the induction of immune responses, but did not address a potential role of sex chromosomes in the CNS response to immune-mediated injury. Here, we examined this possibility using XX versus XY bone marrow chimeras reconstituted with a common immune system of one sex chromosomal type. We found that experimental autoimmune encephalomyelitis mice with an XY sex chromosome complement in the CNS, compared with XX, demonstrated greater clinical disease severity with more neuropathology in the spinal cord, cerebellum, and cerebral cortex. A candidate gene on the X chromosome, toll-like receptor 7, was then examined. Toll-like receptor 7 expression in cortical neurons was higher in mice with XY compared with mice with XX CNS, consistent with the known neurodegenerative role for toll-like receptor 7 in neurons. These results suggest that sex chromosome effects on neurodegeneration in the CNS run counter to effects on immune responses, and may bear relevance to the clinical enigma of greater MS susceptibility in women but faster disability progression in men. This is a demonstration of a direct effect of sex chromosome complement on neurodegeneration in a neurological disease.

The Endocrine Milieu and CD4 T-Lymphocyte Polarization during Pregnancy

Acceptance of the fetal semi-allograft by the mother's immune system has become the focus of intensive research. CD4+ T cells are important actors in the establishment of pregnancy. Th1/Th2 paradigm has been expanded to include CD4+ regulatory T (Treg) and T helper 17 (Th17) cells. Pregnancy hormones exert very significant modulatory properties on the maternal immune system. In this review, we describe mechanisms by which the endocrine milieu modulates CD4 T cell polarization during pregnancy. We first focused on Treg and Th17 cells and on their importance for pregnancy. Secondly, we review the effects of pregnancy hormones [progesterone (P4) and estradiol (E2)] on immune cells previously described, with a particular attention to human chorionic gonadotropin (hCG). The importance of Treg cells for pregnancy is evidenced. They are recruited before implantation and are essential for pregnancy maintenance. Decreased number or less efficient Treg cells are implicated in fertility disorders. As for Th17 cells, the few available studies suggest that they have a negative impact on fertility. Th17 frequency is increased in infertile patients. With the combination of its pro-effects on Th2 and Treg cells and anti-effects on Th1 and Th17 cells, P4 contributes to establishment of a favorable environment for pregnancy. E2 effects are more dependent on the context but it seems that E2 promotes Treg and Th2 cells while it inhibits Th1 cells. hCG positively influences activities of Treg and uterine natural killer cells. This embryo signal is an essential actor for the success of pregnancy, both as the endocrine factor regulating P4 secretion by the ovarian corpus luteum, but also as a paracrine agent during implantation as well as an angiogenic and immunologic mediator during the course of gestation. Luteinizing hormone (LH) immune properties begin to be studied but its positive impact on Treg cells suggests that LH could be a considerable immunomodulator in the mouse.

The influence of pregnancy on systemic immunity

Adaptations in maternal systemic immunity are presumed to be responsible for observed alterations in disease susceptibility and severity as pregnancy progresses. Epidemiological evidence as well as animal studies have shown that influenza infections are more severe during the second and third trimesters of pregnancy, resulting in greater morbidity and mortality, although the reason for this is still unclear. Our laboratory has taken advantage of 20 years of experience studying the murine immune response to respiratory viruses to address questions of altered immunity during pregnancy. With clinical studies and unique animal model systems, we are working to define the mechanisms responsible for altered immune responses to influenza infection during pregnancy and what roles hormones such as estrogen or progesterone play in these alterations.

Estrogenic modulation of uropathogenic Escherichia coli infection pathogenesis in a murine menopause model

Recurrent urinary tract infections (UTIs), primarily caused by uropathogenic Escherichia coli (UPEC), annually affect over 13 million patients in the United States. Menopausal women are disproportionally susceptible, suggesting estrogen deficiency is a significant risk factor for chronic and recurrent UTI. How estrogen status governs susceptibility to UTIs remains unknown, and whether hormone therapy protects against UTIs remains controversial. Here, we used a mouse model of surgical menopause by ovariectomy and demonstrate a protective role for estrogen in UTI pathogenesis. We found that ovariectomized mice had significantly higher bacteriuria, a more robust inflammatory response, and increased production of the proinflammatory cytokine interleukin-6 (IL-6) upon UPEC infection compared to sham-operated controls. We further show that response of the urothelial stem cell niche to infection, normally activated to restore homeostasis after infection, was aberrant in ovariectomized mice with defective superficial urothelial cell differentiation. Finally, UPEC-infected ovariectomized mice showed a significant increase in quiescent intracellular bacterial reservoirs, which reside in the urothelium and can seed recurrent infections. Importantly, this and other ovariectomy-induced outcomes of UTI were reversible upon estrogen supplementation. Together, our findings establish ovariectomized mice as a model for UTIs in menopausal women and pinpoint specific events during course of infection that are most susceptible to estrogen deficiency. These findings have profound implications for the understanding of the role of estrogen and estrogen therapy in bladder health and pathogen defense mechanisms and open the door for prophylaxis for menopausal women with recurrent UTIs.

Effect of gonadal steroid hormones on formalin-induced temporomandibular joint inflammation

We have recently demonstrated that gonadal steroid hormones decrease formalin-induced temporomandibular joint nociception in rats. Given that the attenuation of inflammation is a potential mechanism underlying this antinociceptive effect, we evaluated the effect of gonadal steroid hormones on formalin-induced temporomandibular joint inflammation. Plasma extravasation, a major sign of acute inflammation, and neutrophil migration, an important event related to tissue injury, were evaluated. Formalin induced significantly lower temporomandibular joint plasma extravasation and neutrophil migration in proestrus females than in males and in diestrus females. Since estradiol serum level is high in proestrus females and low in diestrus females and in males, these findings suggest that the high physiological level of estradiol decreases temporomandibular joint inflammation. Estradiol but not progesterone administration in ovariectomized females significantly decreased formalin-induced plasma extravasation and neutrophil migration, an effect that was blocked by the estrogen receptor antagonist ICI 182780. Plasma extravasation and neutrophil migration were not affected by orchiectomy, but testosterone or estradiol administration in orchidectomized males significantly decreased them. The androgen receptor antagonist flutamide blocked the anti-inflammatory effect of testosterone while ICI 182780 blocked that of estradiol in males. Previous intravenous administration of a nonspecific selectin inhibitor significantly decreased formalin-induced temporomandibular joint nociception and neutrophil migration in males, revealing a potent and positive correlation between temporomandibular joint nociception and inflammation. Taken together, these findings demonstrate a pronounced anti-inflammatory effect of estradiol and testosterone in the temporomandibular joint region and suggest that this effect may mediate, at least in part, the antinociceptive effect of these hormones.

What Have We Learned about the Pathogenesis of Rheumatoid Arthritis from TNF-Targeted Therapy?

Studies of cytokine regulation in rheumatoid arthritis led to the development of TNFα inhibitors which are now used for a number of indications, including rheumatoid arthritis, inflammatory bowel disease, psoriasis, psoriatic arthritis, and ankylosing spondylitis. The widespread use of biologics in the clinic offers unique opportunities for probing disease pathogenesis and this paper provides an overview of rheumatoid arthritis, with a particular emphasis on the impact of anti-TNFα therapy on pathogenetic mechanisms. An overview is also provided on the most commonly used animal models that mimic RA, including adjuvant-induced arthritis, collagen-induced arthritis, TNFα-transgenic mice, and the K/BxN and SKG models. These models have led to significant discoveries relating to the importance of pro-inflammatory cytokines in the pathogenesis of rheumatoid arthritis, resulting from disregulation of the normally finely tuned balance of pro- and anti-inflammatory cytokine signalling. In addition, experimental evidence is discussed suggesting how genetic and environmental factors can contribute to disease susceptibility. The role of effector and regulatory T cells is discussed in the light of the relatively disappointing therapeutic effects of T cell modifying agents such as anti-CD4 antibody and cyclosporin. It is concluded that comprehensive analyses of mechanisms of action of biologics and other drugs entering the clinic will be essential to optimise therapy, with the ultimate aim of providing a cure.

Determinants of central nervous system adult neurogenesis are sex, hormones, mouse strain, age, and brain region

Multiple sclerosis is a sexually dimorphic (SD) disease that causes oligodendrocyte death, but SD of glial cells is poorly studied. Here, we analyze SD of neural progenitors in 6-8 weeks and 6-8 months normal C57BL/6, SJL/J, and BALB/c mice in the subventricular zone (SVZ), dorsolateral horn (DLC), corpus callosum (CC), and parenchyma. With a short 2-h bromodeoxyuridine (BrdU) pulse, no gender and strain differences are present at 6-8 weeks. At 6-8 months, the number of BrdU(+) cells decreases twofold in each sex, strain, and region, indicating that a common aging mechanism regulates BrdU incorporation. Strikingly, 2× more BrdU(+) cells are found in all brain regions in 6-8 months C57BL/6 females versus males, no gender differences in 6-8 months SJL/J, and fewer BrdU(+) cells in females versus males in BALB/cs. The number of BrdU(+) cells modestly fluctuates throughout the estrous cycle in C57BL/6 and SJLs. Castration causes a dramatic increase in BrdU(+) cells in SVZ and DLC. These findings indicate that testosterone is a major regulator of adult neural proliferation. At 6-8 months, the ratio of PDGFRα(+) cells in the CC to BrdU(+) cells in the DLC of both strains, sexes, estrous cycle, and castrated mice was essentially the same, suggesting that BrdU(+) cells in the DLC differentiate into CC oligodendrocytes. The ratio of TUNEL(+) to BrdU(+) cells does not match proliferation, indicating that these events are differentially regulated. Differential regulation of these two processes leads to the variation in glial numbers between gender and strain. Explanations of neural proliferation based upon data from one sex or strain may be very misleading.

Role of estrogen receptor signaling required for endometriosis-like lesion establishment in a mouse model

Endometriosis results from ectopic invasion of endometrial tissue within the peritoneal cavity. Aberrant levels of the estrogen receptor (ER), ERα and ERβ, and higher incidence of autoimmune disorders are observed in women with endometriosis. An immunocompetent mouse model of endometriosis was used in which minced uterine tissue from a donor was dispersed into the peritoneal cavity of a recipient. Wild-type (WT), ERα-knockout (αERKO), and βERKO mice were donors or recipients to investigate the roles of ERα, ERβ, and estradiol-mediated signaling on endometriosis-like disease. Mice were treated with vehicle or estradiol, and resulting location, number, and size of endometriosis-like lesions were assessed. In comparison with WT lesions in WT hosts, αERKO lesions in WT hosts were smaller and fewer in number. The effect of ER status and estradiol treatment on nuclear receptor status, proliferation, organization, and inflammation within lesions were examined. αERKO lesions in WT hosts did not form distal to the incision site, respond to estradiol, or proliferate but did have increased inflammation. WT lesions in αERKO hosts did respond to estradiol, proliferate, and show decreased inflammation with treatment, but surprisingly, progesterone receptor expression and localization remained unchanged. Only minor differences were observed between WT lesions in βERKO hosts and βERKO lesions in WT hosts, demonstrating the estradiol-mediated signaling responses are predominately through ERα. In sum, these results suggest ER in both endometriosis-like lesions and their environment influence lesion characteristics, and understanding these interactions may play a critical role in elucidating this enigmatic disease.

Sex-related factors in multiple sclerosis susceptibility and progression

The pathogenesis of multiple sclerosis (MS) involves complex interactions between genetic susceptibility and environmental triggers. Clinical observations suggest that the study of sex differences might provide important insight into mechanisms of pathogenesis and progression of the disease in patients. MS occurs more frequently in women than in men, indicating that sex-related factors have an effect on an individual's susceptibility to developing the condition. These factors include hormonal, genetic and environmental influences, as well as gene-environment interactions and epigenetic mechanisms. Interestingly, women do not have a poorer prognosis than men with MS despite a higher incidence of the disease and more-robust immune responses, which suggests a mechanism of resilience. Furthermore, the state of pregnancy has a substantial effect on disease activity, characterized by a reduction in relapse rates during the third trimester but an increased relapse rate in the postpartum period. However, pregnancy has little effect on long-term disability in women with MS. The unravelling of the mechanisms underlying these clinical observations in the laboratory and application of the results to the clinical setting is a unique and potentially fruitful strategy to develop novel therapeutic approaches for MS.

Estrogen treatment prevents gray matter atrophy in experimental autoimmune encephalomyelitis

Gray matter atrophy is an important correlate to clinical disability in multiple sclerosis (MS), and many treatment trials include atrophy as an outcome measure. Atrophy has been shown to occur in experimental autoimmune encephalomyelitis (EAE), the most commonly used animal model of MS. The clinical severity of EAE is reduced in estrogen-reated mice, but it remains unknown whether estrogen treatment can reduce gray matter atrophy in EAE. In this study, mice with EAE were treated with either estrogen receptor (ER)-α ligand or ER-β ligand, and diffusion tensor images (DTI) were collected and neuropathology was performed. DTI showed atrophy in the cerebellar gray matter of vehicle-treated EAE mice compared with healthy controls but not in ER-α or ER-β ligand-treated EAE mice. Neuropathology demonstrated that Purkinje cell numbers were decreased in vehicle-treated EAE mice, whereas neither ER ligand-treated EAE groups showed a decrease. This is the first report of a neuroprotective therapy in EAE that unambiguously prevents gray matter atrophy while sparing a major neuronal cell type. Fractional anisotropy (FA) in the cerebellar white matter was decreased in vehicle- and ER-β ligand-treated but not in ER-α ligand-treated EAE mice. Inflammatory cell infiltration was increased in vehicle- and ER-β ligand-treated but not in ER-α ligand-treated EAE mice. Myelin staining was decreased in vehicle-treated EAE mice and was spared in both ER ligand-treated groups. This is consistent with decreased FA as a potential biomarker for inflammation rather than myelination or axonal damage in the cerebellum in EAE.