Estrogen accelerates immune complex glomerulonephritis but ameliorates T cell-mediated vasculitis and sialadenitis in autoimmune MRL lpr/lpr mice

Hormones and B-cell development in health and autoimmunity

The development of B cells into antibody-secreting plasma cells is central to the adaptive immune system as they induce protective and specific antibody responses against invading pathogens. Various studies have shown that, during this process, hormones can play important roles in the lymphopoiesis, activation, proliferation, and differentiation of B cells, and depending on the signal given by the receptor of each hormone, they can have a positive or negative effect. In autoimmune diseases, hormonal deregulation has been reported to be related to the survival, activation and/or differentiation of autoreactive clones of B cells, thus promoting the development of autoimmunity. Clinical manifestations of autoimmune diseases have been associated with estrogens, prolactin (PRL), and growth hormone (GH) levels. However, androgens, such as testosterone and progesterone (P4), could have a protective effect. The objective of this review is to highlight the links between different hormones and the immune response mediated by B cells in the etiopathogenesis of systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and multiple sclerosis (MS). The data collected provide insights into the role of hormones in the cellular, molecular and/or epigenetic mechanisms that modulate the B-cell response in health and disease.

The conneXion between sex and immune responses

There are notable sex-based differences in immune responses to pathogens and self-antigens, with female individuals exhibiting increased susceptibility to various autoimmune diseases, and male individuals displaying preferential susceptibility to some viral, bacterial, parasitic and fungal infections. Although sex hormones clearly contribute to sex differences in immune cell composition and function, the presence of two X chromosomes in female individuals suggests that differential gene expression of numerous X chromosome-linked immune-related genes may also influence sex-biased innate and adaptive immune cell function in health and disease. Here, we review the sex differences in immune system composition and function, examining how hormones and genetics influence the immune system. We focus on the genetic and epigenetic contributions responsible for altered X chromosome-linked gene expression, and how this impacts sex-biased immune responses in the context of pathogen infection and systemic autoimmunity.

Wechselwirkungen zwischen neuroendokrinem System und Immunsystem bei chronisch-entzündlichen Systemerkrankungen

Hormonelle und neuronale Signalwege können die Manifestation einer chronisch-entzündlichen Systemerkrankung entweder begünstigen oder verhindern. Bei bereits manifester Erkrankung modulieren Hormone und Neurotransmitter den Krankheitsverlauf, in dem sie die Krankheitsaktivität erhöhen oder abschwächen. Beispiele hierfür sind der entzündungshemmende Einfluss der körpereigenen und exogenen Glukokortikoide und die entzündungsfördernden Effekte von Stress bei chronisch-entzündlichen Systemerkrankungen. Bei chronisch-entzündlichen Systemerkrankungen ringt das aktivierte Immunsystem mit dem Gehirn und anderen Organsystemen um Energie, was zu vielfältigen Erkrankungsfolgen und Folgeerkrankungen führt: „sickness behaviour“ mit Fatigue-Symptomatik und depressiven Symptomen, Schlafstörungen, Anorexie, Fehl- und Mangelernährung, Knochenabbau, Muskelabbau und kachektische Fettsucht, Insulinresistenz mit Hyperinsulinämie (begleitet von einer Resistenz gegenüber dem Insulin-like growth factor 1), Dyslipidämie, Veränderungen der Steroidhormonachsen, Störungen der Hypothalamus-Hypophysen-Gonaden-Achse, erhöhter Sympathikotonus, herabgesetzte Aktivität des parasympathischen Nervensystems, arterielle Hypertonie und Volumenbelastung, Entzündungsanämie und zirkadiane Rhythmik der Symptomausprägung. Diese für die Patienten gravierenden Folgeerkrankungen, welche den chronisch-entzündlichen Systemerkrankungen inhärent sind, sollten konsequent therapiert werden.

Sex steroids and autoimmune rheumatic diseases: state of the art

In autoimmune rheumatic diseases, oestrogens can stimulate certain immune responses (including effects on B cells and innate immunity), but can also have dose-related anti-inflammatory effects on T cells, macrophages and other immune cells. By contrast, androgens and progesterone have predominantly immunosuppressive and anti-inflammatory effects. Hormone replacement therapies and oral contraception (and also pregnancy) enhance or decrease the severity of autoimmune rheumatic diseases at a genetic or epigenetic level. Serum androgen concentrations are often low in men and in women with autoimmune rheumatic diseases, suggesting that androgen-like compounds might be a promising therapeutic approach. However, androgen-to-oestrogen conversion (known as intracrinology) is enhanced in inflamed tissues, such as those present in patients with autoimmune rheumatic diseases. In addition, it is becoming evident that the gut microbiota differs between the sexes (known as the microgenderome) and leads to sex-dependent genetic and epigenetic changes in gastrointestinal inflammation, systemic immunity and, potentially, susceptibility to autoimmune or inflammatory rheumatic diseases. Future clinical research needs to focus on the therapeutic use of androgens and progestins or their downstream signalling cascades and on new oestrogenic compounds such as tissue-selective oestrogen complex to modulate altered immune responses.

Environmental factors in the pathogenesis of primary Sjögren's syndrome

Primary Sjögren's syndrome (SS) is a systemic autoimmune disease in which exocrine organs, primarily the salivary and lacrimal glands, are targets of chronic inflammation, leading to severe dryness of eyes and mouth. Fatigue and arthralgia are also common, and extraglandular manifestations involving the respiratory, nervous and vascular systems occur in a subset of patients. Persistent activation of the type I interferon system, and autoreactive B and T cells with production of disease-associated autoantibodies are central to the pathogenesis. Genetic polymorphisms that associate with an increased risk of SS have been described, though the risk-increase contributed by the respective variant is generally low. It is thus becoming increasingly clear that genetics cannot alone account for the development of SS and that other, presumably exogenous, factors must play a critical role. Relatively few studies have investigated exposure to potential risk factors prior to SS disease onset. Rather, many factors have been studied in prevalent cases. In this review, we summarize current literature on exogenous factors in the pathogenesis of SS including infections, hormones, smoking, solvents and additional compounds. We delineate for which factors there is current evidence of increased disease risk, and for which our present knowledge is confined to suggesting their role in SS pathogenesis. Finally, we outline future perspectives in the continued search for environmental risk factors for SS, a research area of great importance considering the possibilities for preventive measures.

The Role of Estrogen Membrane Receptor (G Protein-Coupled Estrogen Receptor 1) in Skin Inflammation Induced by Systemic Lupus Erythematosus Serum IgG

Skin injury is the second most common clinical manifestation in patients with systemic lupus erythematosus (SLE). Estrogen may affect the onset and development of SLE through its receptor. In this study, we investigated the role of estrogen membrane receptor G protein-coupled estrogen receptor 1 (GPER1) in skin injury of SLE. We found that skin injury induced by SLE serum was more severe in female mice and required monocytes. Estrogen promoted activation of monocytes induced by lupus IgG through the membrane receptor GPER1 which was located in lipid rafts. Blockade of GPER1 and lipid rafts reduced skin inflammation induced by SLE serum. The results we obtained suggest that GPER1 plays an important role in the pathogenesis of skin inflammation induced by lupus IgG and might be a therapeutic target in skin lesions of patients with SLE.

Effects of a tissue-selective estrogen complex on B lymphopoiesis and B cell function

BACKGROUND/OBJECTIVE

17β-estradiol (E2) has major effects on the immune system. It induces thymic atrophy, inhibits both T and B lymphopoiesis and stimulates antibody production treatment with E2 has protective effects on the skeleton but is associated with negative side effects in reproductive organs. A tissue-selective estrogen complex (TSEC) comprise of estrogens combined with a selective estrogen receptor modulator (SERM). TSEC therapy displays the bone-protective effects of estrogen, while the negative side effects on reproductive organs are blocked by the SERM. In a recent publication we showed that treatment with the TSEC E2+bazedoxifene (bza) potently inhibits experimental arthritis and associated osteoporosis. In order to elucidate immunological mechanisms involved in those effects, the aim of this study was to investigate how E2+bza treatment affects the healthy immune system.

METHODS

Ovariectomized C57BL/6N mice were treated with vehicle, E2, bza or E2+bza. Weights of uterus and thymus were determined and fluorescence-activated cell sorting was used to analyze B cell populations in bone marrow and spleen. Immunoglobulin production from B cells in bone marrow and spleen were determined using ELISPOT.

RESULTS

Addition of bza to E2-treatment totally antagonized the E2-mediated proliferative effect on uterus. On the contrary, addition of bza to E2-treatment did not block the E2-induced thymic atrophy or inhibition of B lymphopoiesis, and did not block the E2-induced increase in immunoglobulin secretion from bone marrow B cells.

CONCLUSIONS

Addition of bza to E2-treatment blocks E2-induced uteroproliferation but does not alter E2-mediated effects on thymus, B lymphopoiesis or B cell function.

Impact of Estrogen Therapy on Lymphocyte Homeostasis and the Response to Seasonal Influenza Vaccine in Post-Menopausal Women

It is widely recognized that changes in levels of ovarian steroids modulate severity of autoimmune disease and immune function in young adult women. These observations suggest that the loss of ovarian steroids associated with menopause could affect the age-related decline in immune function, known as immune senescence. Therefore, in this study, we determined the impact of menopause and estrogen therapy (ET) on lymphocyte subset frequency as well as the immune response to seasonal influenza vaccine in three different groups: 1) young adult women (regular menstrual cycles, not on hormonal contraception); 2) post-menopausal (at least 2 years) women who are not receiving any form of hormone therapy (HT) and 3) post-menopausal hysterectomized women receiving ET. Although the numbers of circulating CD4 and CD20 B cells were reduced in the post-menopausal group receiving ET, we also detected a better preservation of naïve B cells, decreased CD4 T cell inflammatory cytokine production, and slightly lower circulating levels of the pro-inflammatory cytokine IL-6. Following vaccination, young adult women generated more robust antibody and T cell responses than both post-menopausal groups. Despite similar vaccine responses between the two post-menopausal groups, we observed a direct correlation between plasma 17β estradiol (E2) levels and fold increase in IgG titers within the ET group. These findings suggest that ET affects immune homeostasis and that higher plasma E2 levels may enhance humoral responses in post-menopausal women.

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.

Aromatase and regulation of the estrogen-to-androgen ratio in synovial tissue inflammation: common pathway in both sexes

Sex hormones play an active role in inflammatory responses, with androgens being anti-inflammatory, whereas estrogens have both pro- and anti-inflammatory effects. In rheumatoid arthritis (RA) patients, low levels of androgens and high levels of estrone are found in the synovial fluid. Aromatase is the key enzyme for the conversion of androgens into estrogens. Proinflammatory cytokines stimulate aromatase activity so that the inflammatory milieu can induce conversion of androgens to estrogens. Moreover, testosterone inhibits aromatase activity. As local androgen levels are low in RA, this can contribute to high aromatase activity in the synovium. Importantly, aromatase-converted estrogens are converted into proproliferative and proinflammatory 16-hydroxylated estrogens. A hormone involved in aromatase activity is vitamin D, which downregulates aromatase in human RA macrophages. Collectively, evidence suggests a key role of aromatase in sex hormone balance during chronic inflammation and points to the importance of vitamin D as a possible new tool for aromatase modulation.

Hormonal milieu at time of B cell activation controls duration of autoantibody response

A strong gender bias is seen in many autoimmune diseases including systemic lupus erythematosus (SLE). To investigate the basis for the female preponderance in SLE, we have been studying BALB/c mice in which B cells express the R4A heavy chain of an anti-DNA antibody in association with an endogenous light chain repertoire (R4Atg mice). In unmanipulated mice, approximately 5% of B cells express the R4A transgene. R4Atg mice do not spontaneously develop elevated serum titers of anti-DNA antibodies. Administration of either estradiol (E2) or prolactin (Pr) results in escape from tolerance of autoreactive B cells, expressed as an increase in transgene-expressing B cells and elevated serum titers of anti-DNA antibodies. We previously demonstrated that autoreactive B cells maturing in an estrogenic milieu develop as marginal zone (MZ) B cells; when these same B cells mature in the presence of increased prolactin, they develop as follicular (Fo) B cells. To determine the long term consequence of this differential maturation of DNA-reactive B cells, we treated R4Atg BALB/c mice with E2 or Pr for 6 weeks until serum titers of anti-DNA antibody were high, at which time hormonal exposure was discontinued. In E2-treated mice, the anti-DNA titers remained high even 3 months after discontinuation of hormone exposure. Nascent B cells underwent normal tolerance induction, but existing autoreactive MZ B cells persisted and continued to secrete autoantibody. In contrast, Pr caused only a short-term increase in anti-DNA antibody titers. By 3 months after cessation of hormone treatment, serum anti-DNA antibody titers and B cell subsets were indistinguishable from those in placebo (P) treated mice. These findings suggest that autoantibody responses are sustained for variable lengths of time depending on the B cell subset producing the autoantibodies. This observation may be relevant to understanding the heterogeneous presentation of patients with SLE and to the design of therapies targeting specific B-cell populations in autoimmune disease.

Type I IFN signature in primary Sjögren's syndrome patients

Primary Sjögren's syndrome (pSS) is a systemic autoimmune disease characterized by lymphocytic infiltrates in salivary and lacrimal glands. Clinical manifestations range from ocular and oral dryness to vasculitis and severe fatigue. pSS is a disease with heterogeneous symptoms and a variable response to the available treatment. Recently, a key role for Interferon (IFN) type I has been implicated in the pathogenesis of pSS. As type I IFN consists of 17 different subtypes, it cannot be easily assessed using a conventional ELISA. Therefore the expression of type I IFN inducible genes--the so-called type I IFN signature--is assessed in salivary gland tissue and blood from patients as a readout for type I IFN activity. In this review we discuss the potential of type I IFN as a novel biomarker for disease activity, subclassification of patients, prediction of therapy response and most importantly as a target for therapeutic intervention.

Psoriasis: female skin changes in various hormonal stages throughout life--puberty, pregnancy, and menopause

Psoriasis is one of the most prevalent immune mediated skin diseases worldwide. Despite the large prevalence in both men and women, the pathogenesis of this disease has not yet been fully clarified. Nowadays, it is believed that psoriasis is most likely a T helper Th1/Th17 induced inflammatory disease. Stressful life situations are known to cause flare-ups and psoriasis activity may be linked to stress from major life events. We know that stress greatly affects both the hormone and immune systems and that there are many different hormonal phases throughout a woman's lifetime. The severity of psoriasis may fluctuate or be influenced by each phase and this relationship can be seen as disease frequency seems to peak during puberty, postpartum, and menopause when hormone levels fall, while symptoms improve during pregnancy, a state when hormone levels are increased.

Endocrine-disrupting chemical exposure and the American alligator: a review of the potential role of environmental estrogens on the immune system of a top trophic carnivore

Endocrine-disrupting chemicals (EDCs) alter cellular and organ system homeostasis by interfering with the body's normal physiologic processes. Numerous studies have identified environmental estrogens as modulators of EDC-related processes in crocodilians, notably in sex determination. Other broader studies have shown that environmental estrogens dysregulate normal immune function in mammals, birds, turtles, lizards, fish, and invertebrates; however, the effects of such estrogenic exposures on alligator immune function have not been elucidated. Alligators occupy a top trophic status, which may give them untapped utility as indicators of environmental quality. Environmental estrogens are also prevalent in the waters they occupy. Understanding the effects of these EDCs on alligator immunity is critical for managing and assessing changes in their health and is thus the focus of this review.

The role of carnitine on ovariectomy and inflammation-induced osteoporosis in rats

This study was carried out to assess the protective bone-sparing effect of carnitine with anti-inflammatory properties on chronic inflammation-induced bone loss in ovariectomised (OVX) rats. A total of 64 rats were divided into eight groups. Sixteen rats were sham-operated (SH) while the others were ovariectomised (OVX). (1) SH, (2) sham + inflammation (SHinf), (3) OVX, (4) ovariectomy + inflammation (OVXinf), (5) OVX + CAR1, (6) OVX + CAR2, (7) OVXinf + CAR1, (8) OVXinf + CAR2. After the ovariectomy surgery, all the groups (3, 4, 5, 6, 7, and 8) were allowed to recover for two months. Sixty days after the OVX, inflammation was induced by subcutaneous injections of talc in groups 2, 4, 7, and 8. Group 5 and 7 were given 50 mg/kg CAR; Group 6 and 8 were given 100 mg/kg CAR from the 60th to the 80th day. Serum levels of TNF-α, IL-1, IL-6, OP, and OC were assessed to determine inflammation and to evaluate osteoblastic activity. Bone mineral density (BMD) was assessed by dual energy X-ray absorptiometry in femur bones of rats. Carnitine administration was able to restore BMD up to values measured in both the OVX and the SH animals. The serum levels of TNF-α, IL-1β, and IL-6 were increased significantly in the OVXinf rats compared with the SH group. In OVX rats, inflammation which is evaluated by serum cytokine levels exacerbated this bone loss, as supported by values of BMD of the total femur. The two different doses of carnitine reduced bone loss and improved inflammatory biomarkers.

Role of neuroendocrine and neuroimmune mechanisms in chronic inflammatory rheumatic diseases--the 10-year update

BACKGROUND

Neuroendocrine immunology in musculoskeletal diseases is an emerging scientific field. It deals with the aspects of efferent neuronal and neurohormonal bearing on the peripheral immune and musculoskeletal systems. This review aims to add new information that appeared since 2001.

SEARCH STRATEGY

The following PubMed search sentence was used to find a total of 15,462 references between 2001 and March 2013: "(rheum* OR SLE OR vasculitis) AND (nerve OR hormone OR neurotransmitter OR neuropeptide OR steroid)." In a continuous process, year by year, this search strategy yielded relevant papers that were screened and collected in a database, which build the platform of this review.

RESULTS

The main findings are the anti-inflammatory role of androgens, the loss of androgens (androgen drain), the bimodal role of estrogens (support B cells and inhibit macrophages and T cells), increased conversion of androgens to estrogens in inflammation (androgen drain), disturbances of the gonadal axis, inadequate amount of HPA axis hormones relative to inflammation (disproportion principle), biologics partly improve neuroendocrine axes, anti-corticotropin-releasing hormone therapies improve inflammation (antalarmin), bimodal role of the sympathetic nervous system (proinflammatory early, anti-inflammatory late-most probably due to catecholamine-producing local cells), anti-inflammatory role of alpha melanocyte-stimulating hormone, vasoactive intestinal peptide, and the Vagus nerve via α7 nicotinergic receptors. Circadian rhythms of hypothalamic origin are responsible for circadian rhythms of symptoms (neuroimmune link revealed). Important new pain-sensitizing immunological pathways were found in the last decade.

CONCLUSIONS

The last decade brought much new information that gave birth to the first therapies of chronic inflammatory diseases on the basis of neuroendocrine immune targets. In addition, a new theory linked evolutionary medicine, neuroendocrine regulation of distribution of energy-rich fuels, and volume regulation that can explain many disease sequelae in patients with chronic inflammatory diseases.

Exosomal secretion of death bullets: a new way of apoptotic escape?

Ovariectomy/estrogen deficiency causes selective apoptosis of the serous epithelial cells of the submandibular glands (SMG) in female mice. Because such apoptosis does not occur in healthy, estrogen-deficient male mice, it was hypothesized that dihydrotestosterone (DHT) protects epithelial SMG cells against apoptosis. The antiapoptotic effect of DHT on human epithelial HSG cells exposed to tumor necrosis factor-α and cycloheximide was studied. Correspondingly, the proapoptotic effect of androgen deficiency was studied in orchiectomized (ORX) androgen-knockout (ARKO) and wild-type (WT) mice. The health state of the SMG cells was studied with Alcian blue-periodic acid Schiff (AB-PAS) and amylase staining and transmission electron microscopy (TEM). The eventual protective antiapoptotic effect of dehydroepiandrosterone (DHEA) treatment was tested in this model. Apoptosis was assessed using immunohistochemisty of cleaved effector caspase-3 and its activator caspase-8 and the TUNEL assay. To test for the bioavailability, intracrine metabolism and sex steroid effects of DHEA, cystein-rich secretory protein-3 (CRISP-3), and leucine-isoleucine-valine transport system 1 (LIV-1) were used as androgen- and estrogen-regulated biomarkers, respectively. DHT protected HSG cells against induced apoptosis. In mice, androgen deficiency resulted in extensive activation of apoptotic caspase-8/3 cascade in serous epithelial cells. However, in salivary glands, active caspases were not translocated to nuclei but secreted to salivary ducts in exosome-like particles, which are associated with weak AB-PAS and amylase staining of the androgen-deprived cells and reduced number of intracellular secretory granules. DHEA treatment suppressed induction of proapoptotic caspases and almost normalized mucins and amylase and ultramophology of the serous epithelial cells in WT ORX but not ARKO ORX mice. According to the CRISP-3 and LIV-1 markers, DHEA probably exerted its effects via intracrine conversion to DHT.

The TLR-mediated response of plasmacytoid dendritic cells is positively regulated by estradiol in vivo through cell-intrinsic estrogen receptor α signaling

Plasmacytoid dendritic cells (pDCs) produce large amounts of type I interferons (IFN-α/β) in response to viral or endogenous nucleic acids through activation of their endosomal Toll-like receptors (TLR-7 and TLR-9). Enhanced TLR-7-mediated IFN-α production by pDCs in women, compared with men, has been reported, but whether sex hormones, such as estrogens, are involved in this sex-based difference is unknown. Here we show, in humanized mice, that the TLR-7-mediated response of human pDCs is increased in female host mice relative to male. In a clinical trial, we establish that treatment of postmenopausal women with 17β-estradiol markedly enhances TLR-7- and TLR-9-dependent production of IFN-α by pDCs stimulated by synthetic ligands or by nucleic acid-containing immune complexes. In mice, we found exogenous and endogenous estrogens to promote the TLR-mediated cytokine secretion by pDCs through hematopoietic expression of estrogen receptor (ER) α. Genetic ablation of ERα gene in the DC lineage abrogated the enhancing effect of 17β-estradiol on their TLR-mediated production of IFN-α, showing that estrogens directly target pDCs in vivo. Our results uncover a previously unappreciated role for estrogens in regulating the innate functions of pDCs, which may account for sex-based differences in autoimmune and infectious diseases.

17β-Estradiol (E-2) administration to male (NZB × SWR)F1 mice results in increased IdLNF1-reactive memory T-lymphocytes and accelerated glomerulonephritis

While it has been shown that estradiol treatment accelerates the onset of lupus nephritis with autoantibody production and kidney damage in both male and female lupus-prone mice, the specific mechanism(s) involved are unknown. Our previous work has shown that alterations in IdLNF1-reactive T cells and IdLNF1+ antibodies correlated closely with the onset of autoimmune nephritis in female F1 progeny of SWR and NZB (SNF1) mice, supporting a critical role for the IdLNF1 idiotype in the development of disease. Since male SNF1 mice normally do not develop nephritis, we tested whether administration of 17β-estradiol (E-2) to male SNF1 mice would increase IdLNF1 IgG levels and autoreactive T cells, and further, induce nephritis. We found that E-2-treated male SNF1 mice developed nephritis with the same time course and mean survival as normal female SNF1 mice. Moreover, it appeared that the mechanism involved increased serum IdLNF1+IgG and its deposition in kidney glomeruli, preceded by astriking twofold increase in T-lymphocytes expressing the memory phenotype (CD44+CD45RBlo) predominantly in the IdLNF1-reactive T-cell population. In addition, we noted that cells with this phenotype were increased in the nephritic kidneys of treated mice, suggesting a direct involvement of those cells in the renal pathology. E-2 treatment also induced increased numbers of pathogenic IdLNF1+ antibody-producing B cells and elevated presentation of pathogenic IdLNF1+ peptide. Taken together, these results suggest a mechanism of E-2-induced acceleration of autoimmune disease in lupus-prone mice may involve expansion of autoreactive idiotypic T and B-cell populations.

Estrogen and insulin replacement therapy modulates the expression of insulin-like growth factor-I receptors in the salivary glands of diabetic mice

Diabetes mellitus results in various complications, also compromising the salivary glands. Hormone levels and interactions with cellular receptors are altered, intensifying the damage caused by this disease. Hormone replacement therapy alone or combined with other treatments may reverse this damage, but doubts still exist regarding the efficacy of this procedure. The objective of this study was to evaluate the effect of estrogen replacement therapy combined with insulin treatment on salivary secretory cells and on the expression of insulin-like growth factor (IGF)-I receptors in salivary glands of spontaneously diabetic (NOD) mice. Twenty-five mice were divided into five groups of five animals each: group I (NOD diabetic), group II (NOD diabetic treated with insulin), group III (NOD diabetic treated with estrogen), group IV (NOD diabetic treated with insulin and estrogen), and group V (control Balb/c mice). Group II received insulin, group III received estrogen, and group IV received insulin plus estrogen administered daily for 20 days. Groups I and V received saline for the same period of time to simulate treatment. Glucose and estrogen levels were monitored during treatment, and salivary gland samples were collected at the end of treatment for stereological analysis and immunofluorescence detection of IGF-I receptors. Tissue restructuring and regulation of IGF-I receptors expression were observed in animals submitted to estrogen replacement therapy plus insulin. Estrogen effectively promoted the recovery of salivary secretory cells, demonstrating that this hormone alone, and especially when combined with insulin, might be important for the reversal of hyperglycemia-induced tissue injury.

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 receptors in immunity and autoimmunity

Due to the female predominance of autoimmune diseases, the role of gender and sex hormones in the immune system is of long-term interest. Estrogen's primary effects are mediated via estrogen receptors alpha and beta (ER α/β) that are expressed on most immune cells. ERs are nuclear hormone receptors that can either directly bind to estrogen response elements in gene promoters or serve as cofactors with other transcription factors (i.e., NFkB/AP1). Cytoplasmic ER and membrane associated ER impact specific kinase signaling pathways. ERs have prominent effects on immune function in both the innate and adaptive immune responses. Genetic deficiency of ERα in murine models of lupus resulted in significantly decreased disease and prolonged survival, while ERβ deficiency had minimal to no effect in autoimmune models. The protective effect of ERα in lupus is multifactoral. In arthritis models, ERα agonists appears to mediate a protective effect. The modulation of ERα function appears to be a potential target for therapy in autoimmunity.

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.

The MRL/lpr mouse strain as a model for neuropsychiatric systemic lupus erythematosus

To date, CNS disease and neuropsychiatric symptoms of systemic lupus erythematosus (NP-SLE) have been understudied compared to end-organ failure and peripheral pathology. In this review, we focus on a specific mouse model of lupus and the ways in which this model reflects some of the most common manifestations and potential mechanisms of human NP-SLE. The mouse MRL lymphoproliferation strain (a.k.a. MRL/lpr) spontaneously develops the hallmark serological markers and peripheral pathologies typifying lupus in addition to displaying the cognitive and affective dysfunction characteristic of NP-SLE, which may be among the earliest symptoms of lupus. We suggest that although NP-SLE may share common mechanisms with peripheral organ pathology in lupus, especially in the latter stages of the disease, the immunologically privileged nature of the CNS indicates that early manifestations of particularly mood disorders maybe derived from some unique mechanisms. These include altered cytokine profiles that can activate astrocytes, microglia, and alter neuronal function before dysregulation of the blood-brain barrier and development of clinical autoantibody titres.

Effect of oestrogen on T cell apoptosis in patients with systemic lupus erythematosus

Defective control of T cell apoptosis is considered to be one of the pathogenetic mechanisms in systemic lupus erythematosus (SLE). Oestrogen has been known to predispose women to SLE and also to exacerbate activity of SLE; however, the role of oestrogen in the apoptosis of SLE T cells has not yet been documented. In this study, we investigated the direct effect of oestrogen on the activation-induced cell death of T cells in SLE patients. The results demonstrated that oestradiol decreased the apoptosis of SLE T cells stimulated with phorbol 12-myristate 13-acetate (PMA) plus ionomycin in a dose-dependent manner. In addition, oestradiol down-regulated the expression of Fas ligand (FasL) in activated SLE T cells at the both protein and mRNA levels. In contrast, testosterone increased FasL expression dose-dependently in SLE T cells stimulated with PMA plus ionomycin. The inhibitory effect of oestradiol on FasL expression was mediated through binding to its receptor, as co-treatment of tamoxifen, an oestrogen receptor inhibitor, completely nullified the oestradiol-induced decrease in FasL mRNA expression. Moreover, pre-treatment of FasL-transfected L5178Y cells with either oestradiol or anti-FasL antibody inhibited significantly the apoptosis of Fas-sensitive Hela cells when two types of cells were co-cultured. These data suggest that oestrogen inhibits activation-induced apoptosis of SLE T cells by down-regulating the expression of FasL. Oestrogen inhibition of T cell apoptosis may allow for the persistence of autoreactive T cells, thereby exhibiting the detrimental action of oestrogen on SLE activity.

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

It is clear that estrogen can accelerate and exacerbate disease in some lupus-prone mouse strains. It also appears that estrogen can contribute to disease onset or flare in a subset of patients with lupus. We have previously shown estrogen alters B-cell development to decrease lymphopoiesis and increase the frequency of marginal zone B cells. Furthermore, estrogen diminishes B-cell receptor signaling and allows for the increased survival of high-affinity DNA-reactive B cells. Here, we analyze the contribution of estrogen receptor α or β engagement to the altered B-cell maturation and selection mediated by increased exposure to estrogen. We demonstrate that engagement of either estrogen receptor α or β can alter B-cell maturation, but only engagement of estrogen receptor α is a trigger for autoimmunity. Thus, maturation and selection are regulated differentially by estrogen. These observations have therapeutic implications.

Sugar-free, glycine-stabilized intravenous immunoglobulin prevents skin but not renal disease in the MRL/lpr mouse model of systemic lupus

Intravenous immunoglobulin (IVIG) has a therapeutic potential in many autoimmune diseases. Based on its immune modulating and complement inhibiting effects, IVIG has been tested in systemic lupus erythematosus (SLE), but due to osmotic tubular injury caused by immunoglobulin-stabilizing sugar components, lupus nephritis had been accelerated in some patients, thus IVIG use in SLE has been abandoned. The availability of non-sugar-stabilized IVIG raised the possible re-evaluation of IVIG for SLE. We investigated high-dose, long-term non-sugar-stabilized IVIG treatment on skin and renal SLE manifestations in the MRL/lpr mouse model. Animals were treated once a week with glycine-stabilized IVIG or saline (0.2 ml/ 10 g BW) from 6 weeks until they were humanely killed at 5 months of age. IVIG diminished macroscopic cutaneous lupus compared with saline treated mice. Histology and complement-3 immunostaining also demonstrated a significant reduction of skin disease after IVIG treatment. However, renal histology and function were similar in both groups. Compared with typical osmotic tubular damage induced by 5% sucrose and 10% maltose (used for IVIG stabilization), we did not observe any osmotic tubular injury in the glycine-stabilized IVIG treated mice. Our data demonstrate a beneficial effect of IVIG on skin lupus without renal side-effects. Deeper understanding of the organ-specific pathomechanism may aid an individualized SLE therapy.

The impact of hormone replacement therapy on humoral and cell-mediated immune responses in vivo in post-menopausal women with rheumatoid arthritis

It is well known that oestrogen has immunomodulatory properties. We have previously shown disease ameliorating effects of hormone replacement therapy (HRT) in post-menopausal women with rheumatoid arthritis (RA). The aim of this study was to investigate the effects of HRT and the patients inflammatory state on humoral and cell-mediated immune responses. Eighty-eight post-menopausal RA women were allocated to receive HRT (oestradiol and noretisterone acetate), vitamin D3 and calcium or vitamin D3 and calcium alone in a 2-year randomized controlled trial. Immunoglobulins (IgM, IgG and IgA) in serum were measured by nephelometry and rheumatoid factor (RF) concentration by enzyme-linked immunosorbent assay. Immunization with influenza vaccine was performed to quantitate humoral response to recall antigen and tuberculin skin test with purified protein derivative (PPD) to test T-cell-mediated immune response. These immune related measures were correlated with demographic and disease-related variables. HRT during 2 years did not alter concentrations of Ig, RF, IgM response to influenza vaccine or the PPD reaction. The increase in IgM against influenza vaccine was significantly positively correlated with signs of disease activity; C-reactive protein, disease activity score 28 and inversely with haemoglobin. In contrast, PPD reactivity was inversely associated with disease activity. In conclusion, long-term HRT in RA does not influence Ig or autoantibody concentrations in serum and has no significant impact on humoral and cell-mediated immune responses to recall antigens. Interestingly, high disease activity was associated to increased humoral but decreased cell-mediated immune responses irrespectively of hormone treatment.

Hormonal regulation of B-cell function and systemic lupus erythematosus

The prevalence of systemic lupus erythematosus (SLE) is far higher in females than in males and numerous investigations to understand this gender bias have been performed, which propose as casual actors genetic predispositions and sex hormones effects. We will describe in this review how the sex hormones estrogen and prolactin influence B cell maturation and selection, permitting B cells to mature to immunocompetence in a mouse model of lupus. Finally, we will discuss the relevance and implications of these results for human disease.

Estrogen distinctively modulates spleen DC from (NZB x NZW) F1 female mice in various disease development stages

Estrogen is important in the pathogenesis of systemic lupus erythematosus (SLE). The modulation of estrogen on dendritic cells (DCs) may involve in SLE development. Our purpose was to find out whether in vitro the effect of estrogen on DCs is correlated with the disease progression in vivo. We compared the effects of 17beta-estradiol (E2) on spleen DCs from SLE murine model-(NZB x NZW) F1 female mice before and after the disease onset. Results showed that E2 changed the surface molecule CD40, cytokines IL-6, IL-10, IL-12 and TNFalpha and stimulatory ability of spleen DCs from the mice. Selective estrogen receptor modulator-tamoxifen (TAM) could antagonize E2 effects and E2 could influence estrogen receptor (ER alpha) level in DCs. The changes of DCs from various age old mice were different even contrast. So E2 participates in SLE through modulating DCs by binding ER alpha. The effects of E2 on DCs from mice in various disease progression stages were different.

Autosomal loci associated with a sex-related difference in the development of autoimmune phenotypes in a lupus model

Sex-related differences (SrD) are a general characteristic of human autoimmune diseases. There is an increasing body of evidence that suggests a link between sex-related hormones and autoimmune onsets. Here, through a genetic approach using a lupus mouse model, we attempted to show the involvement of genetic factors in the development of SrD in autoimmune diseases. Using MRL/lpr x (MRL/lpr x C57BL/6.Fas(lpr))F1 (MBN2) mice, the whole genome was searched to identify linkage loci to autoimmune phenotypes inherited from a lupus MRL/Mp.Fas(lpr) (MRL/lpr) strain of mice, which exhibits glomerulonephritis, splenomegaly and antinuclear autoantibody. The genome-wide association study confirmed four linkage loci on chromosomes 4, 7, 13, and 17. Furthermore, differential analyses performed using male and female groups of MBN2 mice revealed that two loci located on chromosomes 4 (41-72 cM, MRL/lpr allele) and 7 (4-21 cM, B6/lpr allele) were male specific and suppressed autoimmune phenotypes. Notably, the sum effect of the two loci adequately explained a range of SrD developed in the MBN2 mice. Our present findings suggest the presence of a male-predominant mechanism underlying the development of SrD in autoimmunity, depending on the effects of autosomal loci under an undefined male-specific condition.

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.

Sexual Dimorphism in Superantigen Shock Involves Elevated TNF-α and TNF-α–induced Hepatic Apoptosis

RATIONALE

There is conflicting evidence regarding sex differences in the outcome from severe sepsis and toxic shock. Superantigen-mediated toxic shock affects a higher proportion of female patients.

OBJECTIVES

The objective of the current study was to investigate sexual dimorphism in superantigen-associated sepsis and in superantigen-mediated shock and to identify the key mechanisms responsible for this sex difference.

METHODS

We measured mortality and serum cytokines after induction of sepsis with isogenic superantigen-positive and superantigen-negative Streptococcus pyogenes in HLA class II transgenics. During superantigen-mediated toxic shock, we measured mortality, T-cell responses, systemic tumor necrosis factor (TNF)-alpha and TNF receptors, TNF-alpha-induced hepatocyte apoptosis, and conditioning of these responses by tamoxifen treatment.

MEASUREMENTS AND MAIN RESULTS

In both superantigen-associated sepsis and in superantigen-mediated shock, serum TNF-alpha was increased in females compared with males. This was not attributable to a detectable difference in splenic TNF-alpha transcription; rather, serum soluble TNF receptors were higher in males. Pretreatment of females with the estrogen receptor modulator tamoxifen increased serum soluble TNF receptors, reduced the early serum TNF-alpha response, and improved mortality in females challenged with staphylococcal enterotoxin B. Lethal superantigen shock was characterized by hepatocyte apoptosis, and was reproduced by injection of TNF-alpha. Females had enhanced susceptibility to TNF-alpha-mediated lethality. TNF-alpha-induced hepatocyte apoptosis was greater in females, and was reduced by tamoxifen pretreatment.

CONCLUSIONS

Sexual dimorphism in experimental superantigen toxic shock results from increased systemic TNF-alpha in females, coupled with an increased susceptibility to TNF-alpha-induced hepatocyte apoptosis. Both processes are abrogated by estrogen receptor modulators.

The complex role of estrogens in inflammation

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

Structure-function relationship of estrogen receptor alpha and beta: impact on human health

17Beta-estradiol (E2) controls many aspects of human physiology, including development, reproduction and homeostasis, through regulation of the transcriptional activity of its cognate receptors (ERs). The crystal structures of ERs with agonists and antagonists and the use of transgenic animals have revealed much about how hormone binding influences ER conformation(s) and how this conformation(s), in turn, influences the interaction of ERs with co-activators or co-repressors and hence determines ER binding to DNA and cellular outcomes. This information has helped to shed light on the connection between E2 and the development or progression of numerous diseases. Current therapeutic strategy in the treatment of E2-related pathologies relies on the modulation of ER trancriptional activity by anti-estrogens; however, data accumulated during the last five years reveal that ER activities are not only restricted to the nucleus. ERs are very mobile proteins continuously shuttling between protein targets located within various cellular compartments (e.g., membrane, nucleus). This allows E2 to generate different and synergic signal transduction pathways (i.e., non-genomic and genomic) which provide plasticity for cell response to E2. Understanding the structural basis and the molecular mechanisms by which ER transduce E2 signals in target cells will allow to create new pharmacologic therapies aimed at the treatment of a variety of human diseases affecting the cardiovascular system, the reproductive system, the skeletal system, the nervous system, the mammary gland, and many others.

Miscellaneous diseases affected by pregnancy

Miscellaneous groups of dermatoses are associated with pregnancy and affected by gestation, but they do not coincide with any known classifications. They are inflammatory in nature and include psoriasis, acne, hidradenitis suppurativa, atopic dermatitis, and erythema multiforme. Such dermatoses can either improve or worsen during pregnancy. This review focuses on the changes that can occur during the pregnant state.

Immune responses and bone loss: the estrogen connection

In addition to its effects on sexual differentiation and reproduction, estrogen has important impact on the immune system and on bone. It has also been evident that the effects of estrogen on bone to a large extent are mediated via its action on immune cells. Estrogen has a dichotomous impact on the immune system by downregulation of inflammatory immune responses but simultaneous upregulation of immunoglobulin production. Consequently, immune-mediated diseases in humans and in animal models are modulated by estrogen. Estrogen deficiency after ovariectomy in mice and after menopause in women is associated with significant bone loss. In rheumatic diseases such as rheumatoid arthritis (RA), osteoporosis is frequent, and in patients with postmenopausal RA, the degree of bone loss is dramatically increased. Hormone replacement therapy (HRT) in murine and human arthritis has beneficial effects on bone loss, as expected, but it also ameliorates inflammation and inflammation-triggered joint destruction. Long-term use of HRT has been associated with increased risk of breast cancer, thrombosis, and possibly also stroke. Accordingly, there is great need for new activators of estrogen receptors (ERs) selectively reproducing only the beneficial effects of estrogen. To achieve this aim, better knowledge of the mechanisms of how activation of ER-alpha and ER-beta modulates the immune system and bone at the cellular and molecular levels is necessary.

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

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

Estrogen enhances susceptibility to experimental autoimmune myasthenia gravis by promoting type 1-polarized immune responses

Myasthenia gravis (MG) is an organ-specific autoimmune disease caused in most cases by autoantibodies against the nicotinic acetylcholine receptor (AChR). It is now well documented that many autoimmune diseases, including MG, are more prevalent in women than in men, and that fluctuations in disease severity occur during pregnancy. These observations raise the question of the potential role of sex hormones, such as estrogens, as mediators of sex differences in autoimmunity. In the present study, we have analyzed the effect of 17beta-estradiol (E2) on the pathogenesis of experimental autoimmune myasthenia gravis (EAMG), an animal model of MG. We show that treatment with E2 before Ag priming is necessary and sufficient to promote AChR-specific Th1 cell expansion in vivo. This time-limited exposure to E2 enhances the production of anti-AChR IgG2a(b) (specific for b allotype; e.g., B6) and IgG2b, but not IgG1, and significantly increases the severity of EAMG in mice. Interestingly, the E2-mediated augmentation in AChR-specific Th1 response correlates with an enhanced production of IL-12 by splenic APCs through the recruitment of CD8alpha(+) dendritic cells. These data provide the first evidence that estrogen enhances EAMG, and sheds some light on the role of sex hormones in immune responses and susceptibility to autoimmune disease in women.

A soy diet accelerates renal damage in autoimmune MRL/Mp-lpr/lpr mice

Isoflavones, which are phytoestrogens present in large quantities in soy and soy-derived products, have estrogenic activity, inhibit protein tyrosine kinase, and exert other effects in the human body. Thus, the recent spread of soy consumption in Western populations emphasizes the need to more fully understand the potential effects in the body, especially in abnormal immune conditions. In the present study, the influence of a soy diet on lupus disease in MRL/Mp-lpr/lpr (MRL/lpr) mice was investigated. Weanling female MRL/lpr mice (4 weeks) were fed a soy diet (20% soybean protein and 5% soybean oil). The soy diet exacerbated renal damage; findings in this mouse strain included accelerated proteinuria, elevated serum creatinine concentrations, and reduced creatinine clearance. No effects were detected, however, in C3H/HeN mice, which have the same H-2(k) genetic background as MRL/lpr mice do. A tendency toward an increase in thymus weight and proliferation of T cells in spleen and B cells in lymph nodes were found at the age of 16 weeks. These findings indicate that a soy diet, in comparison with a casein diet, significantly exacerbates the clinical course of this autoimmune disease. Further research on the mechanism of this effect of soy-rich diets is needed, and isoflavone supplementation for systemic lupus erythematosus patients should be carefully reevaluated.

[Estrogen use in systemic lupus erythematosus]

The role of exogenous estrogen in the initiation and maintenance of human systemic lupus erythematosus (SLE) remains very controversial. To review the current literature of the safety of using exogenous estrogens in patients with SLE, a Medline search for articles published between 1970 et 2004 regarding this relationship was performed. Although cohort studies suggest an increase in the incidence of SLE with both oral contraceptives and hormone replacement therapy, recent retrospective studies suggest that the risk of flares is not increased with hormone replacement therapy. Large prospective double blind placebo controlled studies inclusive of all ethnic groups such as the Safety of Estrogen in Lupus Erythematosus National Assessment (SELENA) trial had to provide the basis for definitive recommendations but it had been interrupted after WHI study results.