Estrogen potentiates treatment with T-cell receptor protein of female mice with experimental encephalomyelitis

Benzophenone-3 exposure alters composition of tumor infiltrating immune cells and increases lung seeding of 4T1 breast cancer cells

Environmental chemicals are a persistent and pervasive part of everyday life. A subset of environmental chemicals are xenoestrogens, compounds that bind to the estrogen receptor (ER) and drive estrogen-related processes. One such chemical, benzophenone-3 (BP3), is a common chemical in sunscreen. It is a potent UV protectant but also is quickly absorbed through the skin. While it has been approved by the FDA, there is a renewed interest in the safety of BP3, particularly in relation to breast cancer. The focus of this study was to examine the impact that BP3 has on triple negative breast cancer (TNBC) through alterations to cells in the immune microenvironment. In this study, we exposed female mice to one of two doses of BP3 before injecting them with a TNBC cell line. Several immune endpoints were examined both in the primary tissues and from in vitro studies of T cell behavior. Our studies revealed that in the lung tumor microenvironment, exposure to BP3 not only increased the number of metastases, but also the total area of tumor coverage. We also found that BP3 caused alterations in immune populations in a tissue-dependent manner, particularly in T cells. Taken together, our data suggest that while BP3 may not directly affect the proliferation of TNBC, growth and metastasis of TNBC-derived tumors can be altered by BP3 exposures via the alterations in the immune populations of the tumor microenvironment.

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.

Pulsed administration for physiological estrogen replacement in mice

Estrogens are important regulators of body physiology and have major effects on metabolism, bone, the immune- and central nervous systems. The specific mechanisms underlying the effects of estrogens on various cells, tissues and organs are unclear and mouse models constitute a powerful experimental tool to define the physiological and pathological properties of estrogens. Menopause can be mimicked in animal models by surgical removal of the ovaries and replacement therapy with 17β-estradiol in ovariectomized (OVX) mice is a common technique used to determine specific effects of the hormone. However, these studies are complicated by the non-monotonic dose-response of estradiol, when given as therapy. Increased knowledge of how to distribute estradiol in terms of solvent, dose, and administration frequency, is required in order to accurately mimic physiological conditions in studies where estradiol treatment is performed. In this study, mice were OVX and treated with physiological doses of 17β-estradiol-3-benzoate (E2) dissolved in miglyol or PBS. Subcutaneous injections were performed every 4 days to resemble the estrus cycle in mice. Results show that OVX induces an osteoporotic phenotype, fat accumulation and impairment of the locomotor ability, as expected. Pulsed administration of physiological doses of E2 dissolved in miglyol rescues the phenotypes induced by OVX. However, when E2 is dissolved in PBS the effects are less pronounced, possibly due to rapid wash out of the steroid.

Estrogen Receptor-α Suppresses Liver Carcinogenesis and Establishes Sex-Specific Gene Expression

Estrogen protects females from hepatocellular carcinoma (HCC). To determine whether this protection is mediated by classic estrogen receptors, we tested HCC susceptibility in estrogen receptor-deficient mice. In contrast to a previous study, we found that diethylnitrosamine induces hepatocarcinogenesis to a significantly greater extent when females lack Esr1, which encodes Estrogen Receptor-α. Relative to wild-type littermates, Esr1 knockout females developed 9-fold more tumors. Deficiency of Esr2, which encodes Estrogen Receptor-β, did not affect liver carcinogenesis in females. Using microarrays and QPCR to examine estrogen receptor effects on hepatic gene expression patterns, we found that germline Esr1 deficiency resulted in the masculinization of gene expression in the female liver. Six of the most dysregulated genes have previously been implicated in HCC. In contrast, Esr1 deletion specifically in hepatocytes of Esr1 conditional null female mice (in which Cre was expressed from the albumin promoter) resulted in the maintenance of female-specific liver gene expression. Wild-type adult females lacking ovarian estrogen due to ovariectomy, which is known to make females susceptible to HCC, also maintained female-specific expression in the liver of females. These studies indicate that Esr1 mediates liver cancer risk, and its control of sex-specific liver gene expression involves cells other than hepatocytes.

Regulation of aromatase in cancer

The regulation of aromatase, an enzyme involved in the biosynthesis of estrogen in normal and cancer cells, has been associated with growth factor signaling and immune response modulation. The tissue-specific regulatory roles of these factors are of particular importance as local aromatase expression is strongly linked to cancer development/progression and disease outcomes in patients. Therefore, aromatase has become a chemotherapeutic target and aromatase inhibitors (AIs) are used in the clinic for treating hormone-dependent cancers. Although AIs have shown promising results in the treatment of cancers, the emerging increase in AI-resistance necessitates the development of new and improved targeted therapies. This review discusses the role of tumor and stromal-derived growth factors and immune cell modulators in regulating aromatase. Current single-agent and combination therapies with or without AIs targeting growth factors and immune checkpoints are also discussed. This review highlights recent studies that show new connections between growth factors, mediators of immune response, and aromatase regulation.

Nuclear receptors, cholesterol homeostasis and the immune system

Cholesterol is essential for maintaining membrane fluidity in eukaryotes. Additionally, the synthetic cascade of cholesterol results in precursor molecules important for cellular function such as lipid raft formation and protein prenylation. As such, cholesterol homeostasis is tightly regulated. Interestingly, it is now known that some cholesterol precursors and many metabolites serve as active signaling molecules, binding to different classes of receptors including the nuclear receptors. Furthermore, many cholesterol metabolites or their nuclear receptors have been implicated in the regulation of the immune system in normal physiology and disease. Therefore, in this focused review, cholesterol homeostasis and nuclear receptors involved in this regulation will be discussed, with particular emphasis on how these cascades influence the immune system.

Diffusion tensor imaging identifies aspects of therapeutic estrogen receptor β ligand-induced remyelination in a mouse model of multiple sclerosis

Diffusion tensor imaging (DTI) has been shown to detect white matter degeneration in multiple sclerosis (MS), a neurodegenerative autoimmune disease that presents with diffuse demyelination of the central nervous system. However, the utility of DTI in evaluating therapeutic remyelination has not yet been well-established. Here, we assessed the ability of DTI to distinguish between remyelination and neuroprotection following estrogen receptor β ligand (Indazole chloride, IndCl) treatment, which has been previously shown to stimulate functional remyelination, in the cuprizone (CPZ) diet mouse model of MS. Adult C57BL/6 J male and female mice received a normal diet (control), demyelination-inducing CPZ diet (9wkDM), or CPZ diet followed by two weeks of a normal diet (i.e., remyelination period) with either IndCl (RM + IndCl) or vehicle (RM + Veh) injections. We evaluated tissue microstructure of the corpus callosum utilizing in vivo and ex vivo DTI and immunohistochemistry (IHC) for validation. Compared to control mice, the 9wkDM group showed decreased fractional anisotropy (FA), increased radial diffusivity (RD), and no changes in axial diffusivity (AD) both in vivo and ex vivo. Meanwhile, RM + IndCl groups showed increased FA and decreased RD ex vivo compared to the RM + Veh group, in accordance with the evidence of remyelination by IHC. In conclusion, the DTI technology used in the present study can identify some changes in myelination and is a valuable translational tool for evaluating MS pathophysiology and therapeutic efficacy.

Inflammation-induced Gro1 triggers senescence in neuronal progenitors: effects of estradiol

BACKGROUND

Inflammation has been proposed to contribute to the decline in adult hippocampal neurogenesis. Proinflammatory cytokines activate transcription of chemokine growth-regulated oncogene α (Gro1) in human and murine hippocampal neuronal progenitor cells (NPC). The goal of this study was to investigate the effects of Gro1 on hippocampal neurogenesis in the presence of inflammation.

METHODS

Human hippocampal NPC were transfected with lentivirus expressing Gro1, and murine NPC and hippocampal neuronal HT-22 cells were treated with Gro1 protein. A plasmid expressing mGro1 was electroporated in the hippocampus of newborn mice that were sacrificed 10 days later. Adult male and female mice were injected with lipopolysaccharide (LPS; 1 mg/kg, i.p in five daily injections) or normal saline. Adult male mice were implanted with pellets releasing 17-β estradiol (E2; 2.5 mg/pellet, 41.666 μg/day release) or placebo for 6 weeks and challenged with LPS or normal saline as above. In both experiments, mice were sacrificed 3 h after the last injection. Hippocampal markers of neurogenesis were assessed in vitro and in vivo by Western blot, real-time PCR, and immunohisto/cytochemistry.

RESULTS

Gro1 induced premature senescence in NPC and HT-22 cells, activating senescence-associated β-galactosidase and the cell cycle inhibitor p16 and suppressing neuroblast proliferation and expression of doublecortin (DCX) and neuron-specific class III beta-tubulin (Tuj-1), both neuroblast markers, while promoting proliferation of neural glial antigen 2 (Ng2)-positive oligodendrocytes. Gro1 overexpression in the hippocampus of newborn mice resulted in decreased neuroblast development, as evidenced by decreased DCX expression and increased expression of platelet-derived growth factor α receptor (PDGFαR), a marker of oligodendrocyte precursors. In adult mice, Gro1 was induced in response to LPS treatment in male but not in female hippocampus, with a subsequent decrease in neurogenesis and activation of oligodendrocyte progenitors. No changes in neurogenesis were observed in females. Treatment with E2 blunted LPS-induced Gro1 in the male hippocampus.

CONCLUSIONS

Inflammation-induced Gro1 triggers neuroblast senescence, thus suppressing new neuron development in the hippocampus. Sex-dependent differences in Gro1 response are attributed to estradiol, which blunts these changes, protecting the female hippocampus from the deleterious effects of inflammation-induced Gro1 on neurogenesis.

Estrogen Promotes Mandibular Condylar Fibrocartilage Chondrogenesis and Inhibits Degeneration via Estrogen Receptor Alpha in Female Mice

Temporomandibular joint degenerative disease (TMJ-DD) is a chronic form of TMJ disorder that specifically afflicts people over the age of 40 and targets women at a higher rate than men. Prevalence of TMJ-DD in this population suggests that estrogen loss plays a role in the disease pathogenesis. Thus, the goal of the present study was to determine the role of estrogen on chondrogenesis and homeostasis via estrogen receptor alpha (ERα) during growth and maturity of the joint. Young and mature WT and ERαKO female mice were subjected to ovariectomy procedures and then given placebo or estradiol treatment. The effect of estrogen via ERα on fibrocartilage morphology, matrix production, and protease activity was assessed. In the young mice, estrogen via ERα promoted mandibular condylar fibrocartilage chondrogenesis partly by inhibiting the canonical Wnt signaling pathway through upregulation of sclerostin (Sost). In the mature mice, protease activity was partly inhibited with estrogen treatment via the upregulation and activity of protease inhibitor 15 (Pi15) and alpha-2-macroglobulin (A2m). The results from this work provide a mechanistic understanding of estradiol on TMJ growth and homeostasis and can be utilized for development of therapeutic targets to promote regeneration and inhibit degeneration of the mandibular condylar fibrocartilage.

Differential effects of high-physiological oestrogen on the degeneration of mandibular condylar cartilage and subchondral bone

The striking predilection of temporomandibular disorders (TMD) in women, especially during gonad-intact puberty or reproductive years, indicates that oestrogen plays an important role in the progression of TMD, but the underlying mechanism remains unclear. In this study, unilateral anterior crossbite (UAC) was used to create temporomandibular joint osteoarthritis (TMJ OA) models in rats, while 17β-estradiol (E₂) injections were applied to mimic patients with high-physiological levels of oestrogen. Micro-CT scanning, histological staining and real-time PCR assays were preformed to observe the degenerative changes in the mandibular condylar cartilage and subchondral bone. The results showed that obvious degradation was found in the condylar cartilage and subchondral bone of rats with UAC procedure, including decreased cartilage thickness, loss of extracellular matrix, increased apoptotic chondrocytes and expression of pro-inflammatory and catabolic factors, decreased bone mineral density and increased osteoclast activity. E₂ supplements aggravated the condylar cartilage degradation but reversed the abnormal bone resorption in the subchondral bone induced by UAC. Our results revealed that high-physiological oestrogen plays a destructive role in condylar cartilage but a protective role in subchondral bone at the early stage of TMJ OA. These dual and distinct effects should be given serious consideration in future OA treatments.

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.

Modeling estrogen receptor-positive breast cancers in mice: is it the best we can do?

The continuous supplementation of mice with supraphysiological doses of estrogen 
for the growth of estrogen receptor-positive breast cancers has been linked to toxicity in the host and perturbation of cancer cells' function that can misguide preclinical studies. Thus, alternative experimental models with circulating levels of estrogens higher than those of mice may represent more suitable hosts to model estrogen receptor-positive breast cancers.

SERMs have substance-specific effects on bone, and these effects are mediated via ERαAF-1 in female mice

The bone-sparing effect of estrogens is mediated primarily via estrogen receptor (ER)α, which stimulates gene transcription through activation function (AF)-1 and AF-2. The role of ERαAF-1 for the estradiol (E2) effects is tissue specific. The selective ER modulators (SERMs) raloxifene (Ral), lasofoxifene (Las), and bazedoxifene (Bza) can be used to treat postmenopausal osteoporosis. They all reduce the risk for vertebral fractures, whereas Las and partly Bza, but not Ral, reduce the risk for nonvertebral fractures. Here, we have compared the tissue specificity of Ral, Las, and Bza and evaluated the role of ERαAF-1 for the effects of these SERMs, with an emphasis on bone parameters. We treated ovariectomized (OVX) wild-type (WT) mice and OVX mice lacking ERαAF-1 (ERαAF-1(0)) with E2, Ral, Las, or Bza. All three SERMs increased trabecular bone mass in the axial skeleton. In the appendicular skeleton, only Las increased the trabecular bone volume/tissue volume and trabecular number, whereas both Ral and Las increased the cortical bone thickness and strength. However, Ral also increased cortical porosity. The three SERMs had only a minor effect on uterine weight. Notably, all evaluated effects of these SERMs were absent in ovx ERαAF-1(0) mice. In conclusion, all SERMs had similar effects on axial bone mass. However, the SERMs had slightly different effects on the appendicular skeleton since only Las increased the trabecular bone mass and only Ral increased the cortical porosity. Importantly, all SERM effects require a functional ERαAF-1 in female mice. These results could lead to development of more specific treatments for osteoporosis.

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.

Estrogen regulates T helper 17 phenotype and localization in experimental autoimmune arthritis

INTRODUCTION

The incidence and progression of many autoimmune diseases are sex-biased, which might be explained by the immunomodulating properties of endocrine hormones. Treatment with estradiol potently inhibits experimental autoimmune arthritis. Interleukin-17-producing T helper cells (Th17) are key players in several autoimmune diseases, particularly in rheumatoid arthritis. The aim of this study was to investigate the effects of estrogen on Th17 cells in experimental arthritis.

METHODS

Ovariectomized DBA/1 mice treated with 17β-estradiol (E2) or placebo were subjected to collagen-induced arthritis (CIA), and arthritis development was assessed. Th17 cells in joints and lymph nodes were studied by flow cytometry. Lymph node Th17 cells were also examined in ovariectomized estrogen receptor α-knockout mice (ERα-/-) and wild-type littermates, treated with E2 or placebo and subjected to antigen-induced arthritis.

RESULTS

E2-treated mice with established CIA showed reduced severity of arthritis and fewer Th17 cells in joints compared with controls. Interestingly, E2-treated mice displayed increased Th17 cells in lymph nodes during the early phase of the disease, dependent on ERα. E2 increased the expression of C-C chemokine receptor 6 (CCR6) on lymph node Th17 cells as well as the expression of the corresponding C-C chemokine ligand 20 (CCL20) within lymph nodes.

CONCLUSIONS

This is the first study in which the effects of E2 on Th17 cells have been characterized in experimental autoimmune arthritis. We report that E2 treatment results in an increase of Th17 cells in lymph nodes during the early phase of arthritis development, but leads to a decrease of Th17 in joints during established arthritis. Our data suggest that this may be caused by interference with the CCR6-CCL20 pathway, which is important for Th17 cell migration. This study contributes to the understanding of the role of estrogen in the development of autoimmune arthritis and opens up new fields for research concerning the sex bias in autoimmune disease.

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.

Multiple functional therapeutic effects of the estrogen receptor β agonist indazole-Cl in a mouse model of multiple sclerosis

Currently available immunomodulatory therapies do not stop the pathogenesis underlying multiple sclerosis (MS) and are only partially effective in preventing the onset of permanent disability in patients with MS. Identifying a drug that stimulates endogenous remyelination and/or minimizes axonal degeneration would reduce the rate and degree of disease progression. Here, the effects of the highly selective estrogen receptor (ER) β agonist indazole chloride (Ind-Cl) on functional remyelination in chronic experimental autoimmune encephalomyelitis (EAE) mice were investigated by assessing pathologic, functional, and behavioral consequences of both prophylactic and therapeutic (peak EAE) treatment with Ind-Cl. Peripheral cytokines from autoantigen-stimulated splenocytes were measured, and central nervous system infiltration by immune cells, axon health, and myelination were assessed by immunohistochemistry and electron microscopy. Therapeutic Ind-Cl improved clinical disease and rotorod performance and also decreased peripheral Th1 cytokines and reactive astrocytes, activated microglia, and T cells in brains of EAE mice. Increased callosal myelination and mature oligodendrocytes correlated with improved callosal conduction and refractoriness. Therapeutic Ind-Cl-induced remyelination was independent of its effects on the immune system, as Ind-Cl increased remyelination within the cuprizone diet-induced demyelinating model. We conclude that Ind-Cl is a refined pharmacologic agent capable of stimulating functionally relevant endogenous myelination, with important implications for progressive MS treatment.

Serine protease inhibition attenuates rIL-12-induced GZMA activity and proinflammatory events by modulating the Th2 profile from estrogen-treated mice

Estrogen has potent immunomodulatory effects on proinflammatory responses, which can be mediated by serine proteases. We now demonstrate that estrogen increased the extracellular expression and IL-12-induced activity of a critical member of serine protease family Granzyme A, which has been shown to possess a novel inflammatory persona. The inhibition of serine protease activity with inhibitor 4-(2-aminoethyl) benzenesulfonyl fluoride hydrochloride significantly diminished enhanced production of proinflammatory interferon-γ, IL-1β, IL-1α, and Granzyme A activity even in the presence of a Th1-inducing cytokine, IL-12 from splenocytes from in vivo estrogen-treated mice. Inhibition of serine protease activity selectively promoted secretion of Th2-specific IL-4, nuclear phosphorylated STAT6A, signal transducer and activator of transcription (STAT)6A translocation, and STAT6A DNA binding in IL-12-stimulated splenocytes from estrogen-treated mice. Inhibition with 4-(2-aminoethyl) benzenesulfonyl fluoride hydrochloride reversed the down-regulation of Th2 transcription factors, GATA3 and c-Maf in splenocytes from estrogen-exposed mice. Although serine protease inactivation enhanced the expression of Th2-polarizing factors, it did not reverse estrogen-modulated decrease of phosphorylated STAT5, a key factor in Th2 development. Collectively, data suggest that serine protease inactivity augments the skew toward a Th2-like profile while down-regulating IL-12-induced proinflammatory Th1 biomolecules upon in vivo estrogen exposure, which implies serine proteases as potential regulators of inflammation. Thus, these studies may provide a potential mechanism underlying the immunomodulatory effect of estrogen and insight into new therapeutic strategies for proinflammatory and female-predominant autoimmune diseases.

The role of total and cartilage-specific estrogen receptor alpha expression for the ameliorating effect of estrogen treatment on arthritis

INTRODUCTION

Estrogen (E2) delays onset and decreases severity of experimental arthritis. The aim of this study was to investigate the importance of total estrogen receptor alpha (ERα) expression and cartilage-specific ERα expression in genetically modified mice for the ameliorating effect of estrogen treatment in experimental arthritis.

METHODS

Mice with total (total ERα-/-) or cartilage-specific (Col2α1-ERα-/-) inactivation of ERα and wild-type (WT) littermates were ovariectomized, treated with E2 or placebo, and induced with antigen-induced arthritis (AIA). At termination, knees were collected for histology, synovial and splenic cells were investigated by using flow cytometry, and splenic cells were subjected to a T-cell proliferation assay.

RESULTS

E2 decreased synovitis and joint destruction in WT mice. Amelioration of arthritis was associated with decreased frequencies of inflammatory cells in synovial tissue and decreased splenic T-cell proliferation. E2 did not affect synovitis or joint destruction in total ERα-/- mice. In Col2α1-ERα-/- mice, E2 protected against joint destruction to a similar extent as in WT mice. In contrast, E2 did not significantly ameliorate synovitis in Col2α1-ERα-/- mice.

CONCLUSIONS

Treatment with E2 ameliorates both synovitis and joint destruction in ovariectomized mice with AIA via ERα. This decreased severity in arthritis is associated with decreased synovial inflammatory cell frequencies and reduced splenic T-cell proliferation. ERα expression in cartilage is not required for estrogenic amelioration of joint destruction. However, our data indicate that ERα expression in cartilage is involved in estrogenic effects on synovitis, suggesting different mechanisms for the amelioration of joint destruction and synovitis by E2.

Prospects for a T-cell receptor vaccination against myasthenia gravis

T-cell receptor (TCR) vaccination has been proposed as a specific therapy against autoimmune diseases. It is already used in clinical trials, which are supported by pharmaceutical companies for the treatment of multiple sclerosis, rheumatoid arthritis and psoriasis. Current vaccine developments are focusing on enhancement of immunogenicity as well as selecting the best route of immunization and adjuvant to favor the therapeutic effect. In the meantime, academic laboratories are tackling the regulatory mechanisms involved in the beneficial effect of the vaccines to further understand how to control the therapeutic tool. Indeed, several examples in experimental models of autoimmune diseases indicate that any specific therapy may rely on a delicate balance between the pathogenic and regulatory mechanisms. This review presents a critical analysis of the potential of such therapy in myasthenia gravis, a prototype antibody-mediated disease. Indeed, a specific pathogenic T-cell target population and a TCR-specific regulatory mechanism mediated by anti-TCR antibodies and involved in protection from the disease have recently been identified in a patient subgroup. The presence of spontaneous anti-TCR antibodies directed against the pathogenic T-cells that may be boosted by a TCR vaccine provides a rationale for such therapy in myasthenia gravis. The development of this vaccine may well benefit from experience gained in the other autoimmune diseases in which clinical trials are ongoing.

Effect of gender on recovery after spinal cord injury

Spinal cord injury (SCI) is a debilitating condition that affects thousands of new individuals each year, the majority of which are males. Males with SCI tend to be injured at an earlier age, mostly during sports or motor vehicle accidents, whereas females tend be injured later in life, particularly in the age group 65 and older. In both experimental and clinical studies, the question as to whether gender affects outcome has been addressed in a variety of patient groups and animal models. Results from experimental paradigms have suggested that a gender bias in outcome exists that favors females and appears to involve the advantageous or disadvantageous effects of the gonadal sex hormones estrogen and progesterone or testosterone, respectively. However, other studies have shown an absence of gender differences in outcome in specific SCI models and work has also questioned the involvement of female sex hormones in the observed outcome improvements in females. Similar controversy exists clinically, in studies that have examined gender disparities in outcome after SCI. The current review examines the experimental and clinical evidence for a gender bias in outcome following SCI and discusses issues that have made it difficult to conclusively answer this question.

Estradiol treatment and hormonal fluctuations during the estrous cycle modulate the expression of estrogen receptors in the auditory system and the prepulse inhibition of acoustic startle response

Estrogens' effects on hearing are documented across species, but the responsible molecular mechanisms remain unknown. The presence of estrogen receptors (ER) throughout the auditory system offers a potential pathway of direct estrogenic effects on auditory function, but little is known about how each ER's expression is regulated by the overall hormonal status of the body. In the present study, we determined the effects of ovariectomy and chronic 17β-estradiol treatment on mRNA and protein expression of ERα and ERβ in peripheral (cochlea) and central (inferior colliculus) auditory structures of mice, as well as on auditory-related behavior using the acoustic startle response (ASR), prepulse inhibition (PPI), and habituation of the startle response. 17β-Estradiol treatment down-regulated ERα but not ERβ and increased PPI and latency of the ASR. Neither the magnitude nor the habituation of ASR was affected. Furthermore, ER's mRNA and protein expression in the inner ear were analyzed throughout the estrous cycle (proestrus, estrus, metestrus, and diestrus), revealing a negative correlation of circulating estrogens with ERα expression, whereas ERβ was stable. Our findings show that ER not only are present in both the peripheral and central auditory system but also that circulating estrogen levels down-regulate ERα expression in the auditory system and affect PPI and the latency of ASR, suggesting a key role of ERα as a hormone-induced modulator of the auditory system and behavior.

Gonadal hormones and oxidative stress interaction differentially affects survival of male and female mice after lung Klebsiella pneumoniae infection

Survival of mice after Klebsiella pneumoniae infection and phagocytosis by alveolar macrophages (AMs), in the presence or absence of ozone (O(3)) exposure prior to infection, is sex dependent. The objective of this work was to study the role of gonadal hormones, 5α-dihydrotestosterone (DHT) and 17β-estradiol (E(2)), on mouse survival after filtered air (FA) or O(3) exposure. Gonadectomized female (G×F) and male (G×M) mice implanted with control or hormone pellets (DHT in G×F, or E(2) in G×M), exposed to O(3) (2 ppm, 3h) or FA, and infected with K. pneumoniae were monitored for survival. Survival in G×F was identical after FA or O(3) exposure; in G×M O(3) exposure resulted in lower survival compared to FA. In O(3)-exposed females, gonadectomy resulted in increased survival compared to intact females or to G×M+E(2). A similar effect was observed in G×F+DHT. The combined negative effect of oxidative stress and hormone on survival was higher for E(2). Gonadectomy eliminated (females) or minimized (males) the previously observed sex differences in survival in response to oxidative stress, and hormone treatment restored them. These findings indicate that gonadal hormones and/or oxidative stress have a significant effect on mouse survival.

Neuroprotective effects of estrogens and androgens in CNS inflammation and neurodegeneration

Multiple sclerosis (MS) is a disease characterized by inflammation and demyelination. Currently, the cause of MS is unknown. Experimental autoimmune encephalomyelitis (EAE) is the most common mouse model of MS. Treatments with the sex hormones, estrogens and androgens, are capable of offering disease protection during EAE and are currently being used in clinical trials of MS. Beyond endogenous estrogens and androgens, treatments with selective estrogen receptor modulators (SERMs) for estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ) are also capable of providing disease protection. This protection includes, but is not limited to, prevention of clinical disease, reduction of CNS inflammation, protection against demyelination, and protection against axonal loss. In EAE, current efforts are focused on using conditional cell specific knockouts of sex hormone receptors to identify the in vivo targets of these estrogens and androgens as well as downstream molecules responsible for disease protection.

GPR30 FORMS AN INTEGRAL PART OF E2-PROTECTIVE PATHWAY IN EXPERIMENTAL AUTOIMMUNE ENCEPHALOMYELITIS

A major focus of our laboratory has been an in-depth evaluation as to how estrogens exert a pronounced protective effect on clinical and histological disease in the animal model of multiple sclerosis (MS), experimental autoimmune encephalomyelitis (EAE). An important issue regarding their therapeutic application has been the undesirable estrogenic side effects thought to be mediated primarily through 17β-estradiol (E2) binding to intracellular estrogen receptor alpha (ERα). With the discovery and characterization of GPR30 as the putative membrane estrogen receptor, we sought to study whether signaling through GPR30 was sufficient to mediate protection against EAE without engagement of ERα. Treatment of EAE in WT mice with G-1, a selective GPR30 agonist, retained estradiol's ability to protect against clinical and histological EAE without estrogenic side effects. G-1 treatment deviated cytokine profiles and enhanced suppressive activity of CD4(+)Foxp3(+) Treg cells through a GPR30- and programmed death 1 (PD-1)-dependent mechanism. This novel finding was indicative of the protective effect of GPR30 activation in EAE and provides a strong foundation for the clinical application of GPR30 agonists such as G-1 in MS. However, future studies are needed to elucidate cross-signaling and evaluate possible additive effects of combined signaling through both GPR30 and ER-α. Deciphering the possible mechanism of involvement of GPR30 in estrogen-mediated protection against EAE may result in lowering treatment doses of E2 and GPR30 agonists that could minimize risks and maximize immunoregulation and therapeutic effects in MS. Alternatively, one might envision using E2 derivatives with reduced estrogenic activity alone or in combination with GPR30 agonists as therapies for both male and female MS patients.

The multi-faceted influences of estrogen on lymphocytes: toward novel immuno-interventions strategies for autoimmunity management

Early studies of the immune system disclosed that, generally, females exhibit stronger responses to a variety of antigens than males. Perhaps as a result of this response, women are more prone to developing autoimmune diseases than men. Yet, the precise cellular and molecular mechanisms remain under investigation. Recently, interferon-gamma and the related pro-inflammatory interleukin-12 were found to be under effects of sex steroid hormones, with potential implications in regulating immune cells and autoimmune responses. In B lymphocytes, functional binding sites for estrogen receptors were identified in the promoter of the gene encoding activation-induced deaminase, an enzyme required for somatic hypermutation, and class-switch recombination. The observation that estrogen exerts direct impacts on antibody affinity-maturation provides a potential mechanism that could account for generating pathogenic high-affinity auto-antibodies. Further deciphering the multi-faceted influences of sex hormones on the responsiveness of immune cells could lead to novel therapeutic interventions for autoimmunity management.

Estrogen-induced protection against experimental autoimmune encephalomyelitis is abrogated in the absence of B cells

Increased remissions in multiple sclerosis (MS) during pregnancy suggest that elevated levels of sex steroids exert immunoregulatory activity. Estrogen (E2=17β-estradiol) protects against experimental autoimmune encephalomyelitis (EAE), but the cellular basis for E2-induced protection remains unclear. Studies demonstrate that depletion of B cells prior to induction of EAE exacerbates disease severity, implicating regulatory B cells. We thus evaluated pathogenic and E2-induced protective mechanisms in B-cell-deficient (μMT(-/-)) mice. EAE-protective effects of E2 were abrogated in μMT(-/-) mice, with no reduction in disease severity, cellular infiltration or pro-inflammatory factors in the central nervous system compared to untreated controls. E2 treatment of WT mice selectively upregulated expression of PD-L1 on B cells and increased the percentage of IL-10-producing CD1d(high) CD5(+) regulatory B cells. Upregulation of PD-L1 was critical for E2-mediated protection since E2 did not inhibit EAE in PD-L1(-/-) mice. Direct treatment of B cells with E2 significantly reduced proliferation of MOG(35-55)-specific T cells that required estrogen receptor-α (ERα). These results demonstrate, for the first time, a requirement for B cells in E2-mediated protection against EAE involving direct E2 effects on regulatory B cells mediated through ERα and the PD-1/PD-L1 negative co-stimulatory pathway. E2-primed B cells may represent an important regulatory mechanism in MS and have strong implications for women receiving current MS therapies that cause B-cell depletion.

Estrogens in rheumatoid arthritis; the immune system and bone

Rheumatoid arthritis (RA) is an autoimmune disease that is more common in women than in men. The peak incidence in females coincides with menopause when the ovarian production of sex hormones drops markedly. RA is characterized by skeletal manifestations where production of pro-inflammatory mediators, connected to the inflammation in the joint, leads to bone loss. Animal studies have revealed distinct beneficial effects of estrogens on arthritis, and a positive effect of hormone replacement therapy has been reported in women with postmenopausal RA. This review will focus on the influence of female sex hormones in the pathogenesis and progression of RA.

Female-biased incidence of experimental autoimmune encephalomyelitis reflects sexually dimorphic expression of surface CTLA-4 (CD152) on T lymphocytes

BACKGROUND

Autoimmune reactions occur naturally and in most cases are controlled by regulatory mechanisms. However, unwanted autoimmune responses still appear in 5% to 7% of the population, in strikingly greater frequencies in women compared with men. The chronic inflammation characteristic of autoimmune diseases is mainly initiated and maintained by autoreactive CD4(+) T lymphocytes. Costimu-lation is required for an optimal response of T lymphocytes: CD28 is a T-cell activator, whereas CTLA-4 (cytotoxic T-lymphocyte antigen 4, also known as CD152) downregulates T-cell activity. Together these costimulatory molecules provide a balance in T-cell immune response.

OBJECTIVE

The aim of this study was to elucidate the role of the inhibitory receptor CTLA-4 in the quality of sex-specific immune responses.

METHODS

At the German Rheumatism Research Center (DRFZ), Berlin, Germany, between 2006 and 2010, we tested mouse strains commonly used for the development of experimental autoimmune encephalomyelitis, the animal model of multiple sclerosis (MS). The SJL mouse strain not only mimics MS pathogenesis, but also exhibits the female predominance that occurs in patients with MS.

RESULTS

Cells derived from SJL females revealed increased proliferation and a doubled frequency of T-helper (Th)1- and Th2-like cytokines, compared with their male counterparts. Moreover, activated Th cells from male mice express significantly higher frequencies (61%) of CTLA-4 expressed at the cell surface in comparison with those of females (46%). Accordingly, close to 50% reduction of CTLA-4 expression occurred in cells of both sexes after the addition of estrogen. We observed that interferon (IFN)-γ(high) production in females occurred in a higher frequency in CD4(+) T cells cultured under neutral conditions (24.6% in females, 15.9% in males). Moreover, we observed that the IFN-yhigh producers were mainly present in females (4.5% vs 0.4% in males).

CONCLUSION

Our results suggest that induction of CTLA-4 expression could serve as a target for an immunomodulatory strategy to downregulate immune responses in sexually dimorphic autoimmune diseases.

Regulatory role of resveratrol on Th17 in autoimmune disease

The immune system is balanced with cells that respond to microbes by developing into effector cells and cells that regulate the activity of effector cells. In many immune responses a subset of effector T cells termed Th17 are necessary for complete immunity because the cytokine IL-17 that they produce is critical to elimination of the pathogen. However, the activity of Th17 must be balance with development of regulatory T cells termed T(regs). Usually, when the activity of the effector cells is excessive and not balanced by regulatory cells of the immune system, there is the increased risk for development of autoimmune diseases. Therefore in many autoimmune diseases the activity of Th17 exceeds that of T(regs). Therapeutics for treatment of autoimmune diseases such as Multiple Sclerosis (MS) have focused upon immunosuppression, immunomodulation, or even immunoablation of effector cells such as Th17 followed by hematopoietic stem cell transplantation. Very few approaches have attempted to therapeutically increase immune regulatory cells such as T(regs) in the treatment of autoimmune disease. This review will focus upon the potential `or the use of resveratrol, a natural plant compound that has already been shown to be a potent anti-inflammatory compound, as a complementary therapeutic for MS that increases the activity of T(regs) even though it also increases development of Th17.

Cyclin D1 enhances the response to estrogen and progesterone by regulating progesterone receptor expression

Estrogen and progesterone are the defining hormones of normal female development, and both play critical roles in breast carcinogenesis. Cyclin D1 is a breast cancer oncogene whose amplification is linked to poor prognosis in estrogen and progesterone receptor-positive breast cancers. Here we report that cyclin D1 regulates progesterone receptor expression, consequently enhancing responses to estrogen and progesterone. Estrogen treatment of cyclin D1 transgenic mice increased progesterone receptor expression and induced mammary hyperplasias that were stimulated by progesterone and blocked by a progesterone antagonist. Progesterone receptor levels decreased in cyclin D1 knockout mice. Cyclin D1 regulated progesterone receptor expression through a novel estrogen- and cyclin D1-responsive enhancer in DNA encoding part of the 3' untranslated region of the progesterone receptor gene. Small inhibitory RNAs for cyclin D1 decreased progesterone receptor expression and estrogen receptor binding to the 3' enhancer region in human breast cancer cells. Since estrogen and progesterone regulate cyclin D1, our results suggest that cyclin D1's participation in a feed-forward loop could contribute to increased breast cancer risks associated with estrogen and progesterone combinations. Additionally, its regulation of the progesterone receptor identifies a novel role for cyclin D1 in ovarian hormone control of breast development and breast carcinogenesis.

PPAR-alpha contributes to the anti-inflammatory activity of 17beta-estradiol

Because studies have shown that 17beta-estradiol (E2) produces anti-inflammatory effects after various adverse circulatory conditions, we have recently demonstrated that E2 significantly reduced the acute lung injury. Moreover, previous results suggest that peroxisome proliferator-activated receptor-alpha (PPAR-alpha), an intracellular transcription factor activated by fatty acids, plays a role in the control of inflammation. With the aim to characterize the role of PPAR-alpha in estrogen-mediated anti-inflammatory activity, we tested the efficacy of E2 in an experimental model of lung inflammation, carrageenan-induced pleurisy, comparing ovariectomized wild-type (WT) and PPAR-alpha lacking (PPAR-alphaKO) mice. Results indicate that E2-mediated anti-inflammatory activity is weakened in PPAR-alphaKO mice, compared with WT control groups. In particular, E2 was less effective in PPAR-alphaKO, compared with WT mice, in inhibition of cell migration as well as lung injury, NF-kB activation, TNF-alpha production, and inducible nitric-oxide synthase (iNOS) activation. Moreover, macrophages from PPAR-alphaKO were less susceptible to E2-induced iNOS inhibition in vitro compared with macrophages from WT mice. Moreover, the results indicate that PPAR-alpha was required for estrogen receptor up-regulation, following E2 treatment. These results show for the first time that PPAR-alpha contributes to the anti-inflammatory activity of E2.

Estrogen controls vitamin D3-mediated resistance to experimental autoimmune encephalomyelitis by controlling vitamin D3 metabolism and receptor expression

Multiple sclerosis (MS) is an autoimmune, neurodegenerative disease with a rapidly increasing female gender bias. MS prevalence decreases with increasing sunlight exposure, supporting our hypothesis that the sunlight-dependent hormone 1,25-dihydroxyvitamin D(3) (1,25-(OH)(2)D(3)) is a natural inhibitor of autoimmune T cell responses in MS. We found that vitamin D(3) inhibited experimental autoimmune encephalomyelitis (EAE) in intact female mice, but not in ovariectomized females or males. To learn whether 17beta-estradiol (E(2)) is essential for vitamin D(3)-mediated protection, ovariectomized female mice were given E(2) or placebo and evaluated for vitamin D(3)-mediated EAE resistance. Diestrus-level E(2) implants alone provided no benefit, but they restored vitamin D(3)-mediated EAE resistance in the ovariectomized females. Synergy between E(2) and vitamin D(3) occurred through vitamin D(3)-mediated enhancement of E(2) synthesis, as well as E(2)-mediated enhancement of vitamin D receptor expression in the inflamed CNS. In males, E(2) implants did not enable vitamin D(3) to inhibit EAE. The finding that vitamin D(3)-mediated protection in EAE is female-specific and E(2)-dependent suggests that declining vitamin D(3) supplies due to sun avoidance might be contributing to the rapidly increasing female gender bias in MS. Moreover, declining E(2) synthesis and vitamin D(3)-mediated protection with increasing age might be contributing to MS disease progression in older women.

Congruent Effects of Estrogen and T-Cell Receptor Peptide Therapy on Regulatory T Cells in EAE and MS

Both estrogen (E2) and T-cell receptor (TCR) peptides have beneficial effects on the clinical course of experimental autoimmune encephalomyelitis (EAE) and possibly multiple sclerosis (MS) that involve distinct but congruent mechanisms. Of interest, these two approaches share an ability to enhance expression of the FoxP3 gene and associated activity of regulatory T (Treg) cells. E2 increases the number and activity of FoxP3(+) T cells through Esr-1 signaling during TCR activation of CD4(+)CD25(-) T cells. In contrast, TCR peptide therapy appears to increase the frequency of regulatory FoxP3(+) T cells specific for self-TCR determinants expressed by targeted pathogenic T cells. The combined effects on Treg expansion and activation induced by these distinct immunoregulatory approaches may account for their potent effects on clinical EAE and argue for a similar combined therapeutic approach for MS.

Sex hormones, brain damage and clinical course of Multiple Sclerosis

There is evidence that gender influences the clinical course of Multiple Sclerosis (MS). Symptom prevalence as well as characteristics differs between the sexes. These differences can be, at least partly, explained by gender differences in the characteristics of tissue damage and disease progression measured by Magnetic Resonance Imaging (MRI). The interaction between sex hormones and MS damage, supported by both MRI and clinical evidence, seems to play an important role in the clinical and sub-clinical gender bias in MS. Experimental data testing directly the effects of sex hormones on brain damage and their clinical relevance show that sex hormones have the potential of exerting anti-inflammatory and protective effects on brain tissue. Both data in experimental models and patient studies discussed in this review encourages a gender-based approach to MS.

Gender and sex hormones in multiple sclerosis pathology and therapy

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

Evaluation of endocrine profile, hypothalamic-pituitary-testis axis and semen quality in multiple sclerosis

Several endocrine and sexual disturbances have been demonstrated in multiple sclerosis (MS) patients of both sexes. The endocrine profile, hypothalamic-pituitary-testis (HPT) axis and semen quality were evaluated in male patients with MS. A total of 68 male MS patients aged 18 years or older were recruited. Forty-eight age-matched healthy male volunteers served as controls. All subjects underwent complete physical examination and routine semen analysis. Two blood samples were drawn from each participant at 15-min intervals for the determination of the resting levels of: luteinising-hormone (LH), follicle-stimulating hormone (FSH), prolactin, testosterone, oestradiol and sex hormone binding globulin. The HPT axis was assessed using gonadotrophin-releasing hormone (GnRH) and human chorionic gonadotrophin tests. The mean basal serum levels for LH, FSH and testosterone in MS patients were significantly lower than the mean for normal controls (P = 0.01). The injection of GnRH analogue did not yield a significant increase in FSH and LH levels in the MS patients compared to normal controls (P = 0.001). Total sperm count, sperm motility and percent normal sperm morphology were lower in MS patients compared to controls. MS subjects with progressive disease had higher and more severe HPT axis abnormalities than that for patients with relapsing remitting MS. Most subjects with MS have hypogonadotrophic hypogonadism state and fertility impairment. It appears that the damage to HPT axis is both in pituitary and testicular levels. Further studies are needed to better elucidate the underlying pathophysiology of HPT axis dysregulation.

17Beta-estradiol expands IgA-producing B cells in mice deficient for the mu chain

Oestrogen is not only a sex hormone but also an important regulator of the immune system. Expression of the heavy chain of IgM (mu) is essential for B-cell differentiation. However, a small number of IgA-positive B cells can be found in mice lacking the mu chain (muMT-/-). The aim of this study was to investigate the effects of oestrogen on this alternative B-cell pathway in muMT-/- mice. Our results clearly demonstrate that oestrogen increases the frequency of IgA-producing B cells in muMT-/- mice in both bone marrow and spleen cells. We also show that mature IgM-producing B cells are not required for oestrogen-mediated suppression of granulocyte-mediated inflammation or thymic involution. In conclusion, we demonstrate that 17beta-estradiol benzoate increases the frequency of IgA-producing B cells in muMT-/- mice, suggesting that oestrogen can influence the alternative B-cell pathway found in muMT-/- mice.

Effects of progesterone in the spinal cord of a mouse model of multiple sclerosis

The spinal cord is a target of progesterone (PROG), as demonstrated by the expression of intracellular and membrane PROG receptors and by its myelinating and neuroprotective effects in trauma and neurodegeneration. Here we studied PROG effects in mice with experimental autoimmune encephalomyelitis (EAE), a model of multiple sclerosis characterized by demyelination and immune cell infiltration in the spinal cord. Female C57BL/6 mice were immunized with a myelin oligodendrocyte glycoprotein peptide (MOG(40-54)). One week before EAE induction, mice received single pellets of PROG weighing either 20 or 100 mg or remained free of steroid treatment. On average, mice developed clinical signs of EAE 9-10 days following MOG administration. The spinal cord white matter of EAE mice showed inflammatory cell infiltration and circumscribed demyelinating areas, demonstrated by reductions of luxol fast blue (LFB) staining, myelin basic protein (MBP) and proteolipid protein (PLP) immunoreactivity (IR) and PLP mRNA expression. In motoneurons, EAE reduced the expression of the alpha 3 subunit of Na,K-ATPase mRNA. In contrast, EAE mice receiving PROG showed less inflammatory cell infiltration, recovery of myelin proteins and normal grain density of neuronal Na,K-ATPase mRNA. Clinically, PROG produced a moderate delay of disease onset and reduced the clinical scores. Thus, PROG attenuated disease severity, and reduced the inflammatory response and the occurrence of demyelination in the spinal cord during the acute phase of EAE.

Role of sex hormones in allergic inflammation in mice

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Transforming growth factor activity is a key determinant for the effect of estradiol on fatty streak deposit in hypercholesterolemic mice

OBJECTIVE

Whereas estradiol prevents fatty streak deposit in immunocompetent apoE-/- or LDLr-/- mice, it is totally ineffective in immunodeficient mice, underlining the key role of immunoinflammation in this effect. In the present work, the role of several major pro- and antiinflammatory cytokines involved in the atheromatous process was evaluated in the effect of estradiol on fatty streak constitution.

METHODS AND RESULTS

The preventive effect of estradiol was fully maintained in LDLr-/- mice grafted with bone marrow from either IFN-gamma or interleukin (IL)-12-deficient mice, showing that this beneficial effect was not mediated through a specific decrease in the production of these 2 proinflammatory cytokines. Furthermore, IL-10-/- apoE-/- mice remained protected by estradiol, excluding a significant contribution of this antiinflammatory cytokine. In contrast, the protective effect of estradiol was (1) associated with enhanced aortic expression of TGF-beta1 in apoE-/- mice during early steps of atherogenesis; (2) abolished and even reversed in apoE-/- mice administered with a neutralizing anti-TGF-beta antibody; (3) abolished in LDLr-/- mice grafted with bone marrow from Smad3-deficient mice.

CONCLUSIONS

The status of the TGF-beta pathway crucially determines the antiatherogenic effect of estradiol in hypercholesterolemic mice, whereas neither IFN-gamma, IL-12, nor IL-10 are specifically involved in this protection.