Female-predominant Autoimmune Diseases Research Articles

Serum autoantibodyome reveals that healthy individuals share common autoantibodies

SUMMARYAutoantibodies are a hallmark of both autoimmune disease and cancer, but they also occur in healthy individuals. Here, we perform a meta-analysis of nine datasets and focus on the common autoantibodies shared by healthy individuals. We report 77 common autoantibodies based on the protein microarray data obtained from probing 182 healthy individual sera on 7,653 human proteins and an additional 90 healthy individual sera on 1,666 human proteins. There is no gender bias; however, the number of autoantibodies increase with age, plateauing around adolescence. We use a bioinformatics pipeline to determine possible molecular-mimicry peptides that can contribute to the elicitation of these common autoantibodies. There is enrichment of intrinsic properties of proteins like hydrophilicity, basicity, aromaticity, and flexibility for common autoantigens. Subcellular localization and tissue-expression analysis reveal that several common autoantigens are sequestered from the circulating autoantibodies.

Progesterone Aggravates Lung Fibrosis in a Mouse Model of Systemic Sclerosis.

BackgroundGender-related factors have explained the higher prevalence of autoimmune diseases in women. Sex hormones play a key role in the immune system and parenchymal cells function; therefore, these hormones can be important in the pathogenesis of autoimmune diseases as a risk or beneficial factor. Lung fibrosis is the main cause of mortality in systemic sclerosis, a female predominant autoimmune disease. The objective of this study was to examine the effect of progesterone on lung fibrosis in a mouse model of systemic sclerosis.MethodsMice with bleomycin-induced lung fibrosis treated with progesterone subcutaneously for 21 and 28 days. Blood was collected for hormone and cytokine measurement at the end of treatment then, skin and lung tissues were harvested for histological assessment, gene expression, cytokine, hydroxyproline, and gelatinase measurement.ResultsTrichrome staining and hydroxyproline measurements showed that progesterone treatment increased the content of collagen in fibrotic and normal lung tissues. Progesterone increased α-SMA (P < 0.01), TGF- β (P < 0.05) and decreased MMP9 (P < 0.05) in fibrotic lung tissues. Also progesterone treatment decreased the gene expression of Col1a2 (P <0.05), Ctgf (P <01), End1 (0.001) in bleomycin- injured lung tissues. The serum level of TNF-α was decreased, but the serum level of cortisol was increased by progesterone treatment in fibrotic mice (P< 0.05).ConclusionOur results showed that progesterone aggravates lung fibrosis in a mouse model of systemic sclerosis.

What should we consider in the case of combined Down- and 47,XY,+i(X)(q10) Klinefelter syndromes? The unique case of a male newborn and review of the literature

BackgroundDouble aneuploidies - especially in combination with structural aberrations - are extremely rare among liveborns. The most frequent association is that of Down (DS) and Klinefelter syndromes (KS). We present the case of a male newborn with a unique 47,XY,+ 21[80%]/48,XY,+i(X)(q10),+ 21[20%] karyotype, hypothesize about his future phenotype, discuss the aspects of management and review the literature.Case presentationThe additional association of isochromosome Xq (i(X)(q10)) could be the result of a threefold non-disjunction event. 47,XY,+i(X)(q10) KS is not common and its symptoms differ from the classical KS phenotype. In combined DS and i(X)(q10) KS, the anticipatory phenotype is not simply the sum of the individual syndromic characteristics. This genotype is associated with higher risk for several diseases and certain conditions with more pronounced appearance: emotional and behavioral disorders; poorer mental and physical quality of life; lower muscle mass/tone/strength; connective tissue weakness; muscle hypotonia and feeding difficulties; osteopenia/−porosis with earlier beginning and faster progression; different types of congenital heart diseases; more common occurrence of hypertension; increased susceptibility to infections and female predominant autoimmune diseases; higher risk for hematological malignancies and testicular tumors.ConclusionsIn multiple aneuploidies, the alterations have the potential to weaken or enhance each other, or they may not have modifying effects at all. Prenatal ultrasound signs are not obligatory symptoms of numerous chromosomal anomalies (specifically those involving supernumerary sex chromosomes), therefore combined prenatal screening has pertinence in uncomplicated pregnancies as well.

Novel mechanism for estrogen receptor alpha modulation of murine lupus

Female sex is a risk factor for lupus. Sex hormones, sex chromosomes and hormone receptors are implicated in the pathogenic pathways in lupus. Estrogen receptor alpha (ERα) knockout (KO) mice are used for defining hormone receptor effects in lupus. Prior studies of ERα KO in lupus have conflicting results, likely due to sex hormone levels, different lupus strains and different ERα KO constructs. Our objective was to compare a complete KO of ERα vs. the original functional KO of ERα (expressing a short ERα) on disease expression and immune phenotype, while controlling sex hormone levels. We studied female lupus prone NZM2410 WT and ERα mutant mice. All mice (n = 44) were ovariectomized (OVX) for hormonal control. Groups of each genotype were estrogen (E2)-repleted after OVX. We found that OVXed NZM mice expressing the truncated ERα (ERα short) had significantly reduced nephritis and prolonged survival compared to both wildtype and the complete ERαKO (ERα null) mice, but surprisingly only if E2-repleted. ERα null mice were not protected regardless of E2 status. We observed significant differences in splenic B cells and dendritic cells and a decrease in cDC2 (CD11b+CD8−) dendritic cells, without a concomitant decrease in cDC1 (CD11b-CD8a+) cells comparing ERα short to ERα null or WT mice. Our data support a protective role for the ERα short protein. ERα short is similar to an endogenously expressed ERα variant (ERα46). Modulating its expression/activity represents a potential approach for treating female-predominant autoimmune diseases.

Therapeutic Interventions of Tissue Specific Autoimmune Onset in Systemic Lupus Erythematosus.

Systemic lupus erythematosus (lupus) is a female predominant autoimmune disease. The autoreactive B cells and T helper cells together are known to develop adverse immune responses in different tissues like kidney, bone, cardiovascular and central nervous system. Progression of disease is associated with deposition of immune complex which initiates tissue damage. The therapy for lupus still includes corticosteroids to reduce allergic manifestations and inflammatory immune responses. Recent observations suggested that, mycophenolate mofetil and cyclophosphamide treatment in combination with corticosteroids have benefit in lupus therapy. The prospect of B cell depletion by CD20 targeted monoclonal antibody Rituximab has been demonstrated in lupus patients. The CD52 specific monoclonal antibody Alemtuzumab is another proposition for lupus therapy. The drug Belimumab inhibits B cell activation by altering BAFF/APRIL signal cascade. Recent discovery of the CD22 targeted Epratuzumab also shows therapeutic prospect. The researches on new generation drugs for autoimmune lupus include search for inhibitors of CD40- CD40Ligand interactions, CD86 activation, selective modulation of complement cascades. The choice of inhibitors of transcription factor NF-κBp65 and selective modulators for estrogen receptor alpha are proposed areas of lupus drug discovery research. Keeping a close eye on the mechanisms of disease onset, a comprehensive view is provided on recent therapy of systemic lupus erythematosus.

Alterations of white matter structural networks in patients with non-neuropsychiatric systemic lupus erythematosus identified by probabilistic tractography and connectivity-based analyses.

PurposeSystemic lupus erythematosus (SLE) is a chronic inflammatory female-predominant autoimmune disease that can affect the central nervous system and exhibit neuropsychiatric symptoms. In SLE patients without neuropsychiatric symptoms (non-NPSLE), recent diffusion tensor imaging studies showed white matter abnormalities in their brains. The present study investigated the entire brain white matter structural connectivity in non-NPSLE patients by using probabilistic tractography and connectivity-based analyses.MethodsWhole-brain structural networks of 29 non-NPSLE patients and 29 healthy controls (HCs) were examined. The structural networks were constructed with interregional probabilistic connectivity. Graph theory analysis was performed to investigate the topological properties, and network-based statistic was employed to assess the alterations of the interregional connections among non-NPSLE patients and controls.ResultsCompared with HCs, non-NPSLE patients demonstrated significantly decreased global and local network efficiencies and showed increased characteristic path length. This finding suggests that the global integration and local specialization were impaired. Moreover, the regional properties (nodal efficiency and degree) in the frontal, occipital, and cingulum regions of the non-NPSLE patients were significantly changed and negatively correlated with the disease activity index. The distribution pattern of the hubs measured by nodal degree was altered in the patient group. Finally, the non-NPSLE group exhibited decreased structural connectivity in the left median cingulate-centered component and increased connectivity in the left precuneus-centered component and right middle temporal lobe-centered component.ConclusionThis study reveals an altered topological organization of white matter networks in non-NPSLE patients. Furthermore, this research provides new insights into the structural disruptions underlying the functional and neurocognitive deficits in non-NPSLE patients.

Evaluation of X Chromosome Inactivation with Respect to HLA Genetic Susceptibility in Rheumatoid Arthritis and Systemic Sclerosis.

BackgroundAutoimmune diseases, including rheumatoid arthritis (RA) and systemic sclerosis (SSc) are characterized by a strong genetic susceptibility from the Human Leucocyte Antigen (HLA) locus. Additionally, disorders of epigenetic processes, in particular non-random X chromosome inactivation (XCI), have been reported in many female-predominant autoimmune diseases. Here we test the hypothesis that women with RA or SSc who are strongly genetically predisposed are less susceptible to XCI bias.MethodsUsing methylation sensitive genotyping of the androgen receptor (AR) gene, XCI profiles were performed in peripheral blood mononuclear cells from 161 women with RA, 96 women with SSc and 100 healthy women. HLA-DRB1 and DQB1 were genotyped. Presence of specific autoantibodies was documented for patients. XCI skewing was defined as having a ratio ≥ 80:20 of cells inactivating the same X chromosome.Results110 women with RA, 68 women with SSc, and 69 controls were informative for the AR polymorphism. Among them 40.9% of RA patients and 36.8% of SSc patients had skewed XCI compared to 17.4% of healthy women (P = 0.002 and 0.018, respectively). Presence of RA-susceptibility alleles coding for the “shared epitope” correlated with higher skewing among RA patients (P = 0.002) and such correlation was not observed in other women, healthy or with SSc. Presence of SSc-susceptibility alleles did not correlate with XCI patterns among SSc patients.ConclusionData demonstrate XCI skewing in both RA and SSc compared to healthy women. Unexpectedly, skewed XCI occurs more often in women with RA carrying the shared epitope, which usually reflects severe disease. This reinforces the view that loss of mosaicism in peripheral blood may be a consequence of chronic autoimmunity.

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

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

The role of icaritin in regulating Foxp3/IL17a balance in systemic lupus erythematosus and its effects on the treatment of MRL/lpr mice

Systemic lupus erythematosus (SLE) is a female predominant autoimmune disease characterized by multi-organ dysfunctions. However, current available therapies control the disease at the cost of many potential adverse effects. The development of safer and more effective therapies for SLE is a critical unmet need. Icaritin (ICT) is an active monomer extracted from Chinese herbals named the Epimedium genus. In this study, we found that ICT exhibited the capacity of regulating Foxp3/IL17a balance, enhancing Treg cell suppressive activities, and inhibiting over-activation of CD4+T cells from SLE. We also observed that ICT regulated Foxp3/IL17a balance by increasing STAT5b expression and histone methylation modification. Subsequent experiments further confirmed that ICT-treated mice exhibited amelioration of renal damages and suggested that ICT may be a potential new drug for the treatment of SLE.

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.

An analysis of expression of lupus-associated miRNAs in splenic lymphocytes from male and female NZB/WF1 mice (P4074)

Abstract Systemic Lupus Erythematosus (SLE) is a prototype, female predominant autoimmune disease. The functional importance and pathogenic contribution of microRNAs (miRNAs) to lupus are now highly recognized. We reported recently a common set of lupus-associated miRNAs including miR-182-96-183 cluster, miR-155, miR-31, and miR-127 in three spontaneous murine lupus models including NZB/WF1. To understand whether miRNAs are differentially expressed in males versus females, and thereby contribute to increased susceptibility to lupus in female NZB/WF1, we analyzed the expression of above miRNAs in splenic lymphocytes from male and female NZB/WF1 mice at different disease stages. Our data indicated that there is no significant difference in the expression of above lupus-associated miRNAs between female and male NZB/WF1 at 17-18wk old, an age before the onset of disease. However, by 23 weeks of age (when NZB/WF1 begin to develop mild lupus disease) the expression levels of miR-182, miR-183, miR-127, and miR-31 were significantly up-regulated in female NZB/WF1 mice compared to age-matched male controls. The expression levels of these miRNAs were further increased in 30 wk old females, following the progression of lupus disease. There was also a slight increasing trend of the above miRNAs in 30 wk old male NZB/WF1 mice when compared to 23 wk old male mice, however it was not significant. Taken together, our study further suggested the association of these miRNAs with lupus development.

Hyperemesis, gestational hypertensive disorders, pregnancy losses and risk of autoimmune diseases in a Danish population-based cohort

The risk of some female predominant autoimmune diseases (ADs) has previously been shown to be higher in women who experience hyperemesis, gestational hypertensive disorders and idiopathic pregnancy losses. This study assessed the association between such pregnancy-related experiences and the subsequent risk of female predominant and other ADs.Our study cohort comprised 1.6 million Danish women born since 1955 for whom we had information about hyperemesis, gestational hypertensive disorders and pregnancy losses and subsequent hospital contacts for 31 ADs between 1982 and 2008. Ratios of first hospitalization rates (RRs) with 95% confidence intervals (CIs) were calculated using Poisson regression, adjusting for age, birth cohort, calendar period, marital status and childbirths.During 27.0 million person-years of follow-up 51,732 women were hospitalized with one or more ADs. Overall, compared with women without the specific pregnancy experiences, the risk of any AD was significantly increased for women with hyperemesis (RR = 1.41; 95% CI 1.30–1.51), gestational hypertensive disorders (1.21; 1.16–1.26), spontaneous abortions (1.10; 1.07–1.14), missed abortions (1.09; 1.04–1.13), stillbirths (1.25; 1.12–1.40), ectopic pregnancies (1.08; 1.02–1.14) and induced abortions (1.07; 1.04–1.09). Associations with female predominant ADs (i.e., ADs with a female:male ratio >2:1) were strongest in the first five years after the studied pregnancy experiences, but overall there was little difference between the RRs for groups of female predominant ADs and other ADs. Strong and potentially biological associations were observed for a number of specific ADs; including systemic lupus erythematosus, Graves’ disease, type 1 diabetes mellitus and pernicious anemia, and for some specific ADs associations persisted even more than five years after the abnormal pregnancy experience.Abnormal pregnancies are associated with increased risk of certain ADs, possibly because of underlying immunologic or hormonal factors that predispose to both adverse pregnancy experiences and AD development.

Estrogen and Signaling in the Cells of Immune System

Hypothalamus-pituitary-gonadal axis regulation of estrogen, which acts on reproductive tissues, is well established. However, it is also evident that estrogens physiologically act on not only reproductive tissues but also on a broad range of tissues such as immune system. It is well documented that estrogen regulates all facets of the immunoregulation thereby affecting the outcome of autoimmune and inflammatory immune responses. Given the broader role of estrogen in immunobiology, it is important to understand how estrogens act on the cells of the immune system. Estrogens act in estrogen receptor dependent and/or independent manner to affect the regulation of cytokines and chemokines. This review focuses on sources and biosynthesis of estrogens, differential expression of estrogen receptors on the cells of immune system, key signaling pathways and its effect on the induction of key pro- and anti-inflammatory cytokines. Since estrogen has contrasting effects in female-predominant autoimmune diseases such as multiple sclerosis (MS) and systemic lupus erythematosus (SLE), we briefly overview the mechanistic role of estrogen on these chronic diseases. Recent evidence suggests that estrogens also alter microRNAs, which regulate a broad range of transcription of genes. The review also addresses this and other newly discovered mechanisms of estrogen-induced immunomodulation in health and disease.

Childbirths and risk of female predominant and other autoimmune diseases in a population-based Danish cohort

To evaluate the possible biological role of pregnancy on the risk of autoimmune diseases we assessed associations between reproductive history and subsequent risk of autoimmune diseases characterized by female predominance and other autoimmune diseases.Our study cohort comprised 4.6 million Danes born since 1935 for whom a complete record of childbirths was available. Cohort members were followed for hospital contacts for 31 autoimmune diseases from 1982 to 2008. Female predominant autoimmune diseases were those with a female:male sex ratio >2:1. Ratios of first hospitalization rates were calculated using Poisson regression, adjusting for potential confounding by age, birth cohort, calendar period and marital status.During 45.5 million person-years of follow-up 102,260 women were hospitalized with one or more autoimmune diseases. Overall, compared with childless women, women with children were at a relative risk of 1.04 (1.02–1.06) for any autoimmune diseases, 1.11 (1.08–1.14) for female predominant and 0.97 (0.95–1.00) for other autoimmune diseases. Possibly biologically related associations with parity were found for Hashimoto thyroiditis (1.11; 1.00–1.24), Graves’ disease (1.19; 1.14–1.24), erythema nodosum (1.15; 1.01–1.32), psoriasis (1.08; 1.01–1.15), sarcoidosis (1.17; 1.06–1.28) and systemic lupus erythematosus (0.83; 0.74–0.93). Especially the one-year postpartum period was associated with an increased risk of Hashimoto thyroiditis, Graves’ disease and sarcoidosis.Overall, parity was associated with an 11% increased risk of female predominant autoimmune diseases. Pregnancies resulting in liveborn children therefore seem to contribute only little to the general female predominance in autoimmune diseases. However, for a number of autoimmune diseases; especially autoimmune thyroid diseases, erythema nodosum and sarcoidosis parity might somehow be involved in disease development.

X chromosome in autoimmune diseases

Autoimmune diseases altogether affect approximately 5% of the population in Western countries, with a higher prevalence in women. Exploring the biological differences between sexes, great attention was focused on hormones and, more recently, on fetal microchimerism, without reaching definitive evidence. Genetic factors are known to be crucial determinants of susceptibility, as shown by family and twin studies, although no specific genes predisposing women to autoimmunity have been identified thus far. In this article, we review recent data regarding X-chromosome abnormalities, such as inactivation patterns and X monosomy, that characterize some female-predominant autoimmune diseases. We believe that future high-throughput tools will help to identify specific clusters of genes on the sex chromosomes that are candidates for disease susceptibility or resistance.

Role of X chromosome defects in primary biliary cirrhosis

Similar to the majority of autoimmune conditions, primary biliary cirrhosis (PBC) is a chronic cholestatic liver disease characterized by a striking female predominance; it is characterized by high titer serum autoantibodies to mitochondrial antigens, elevated serum immunoglobulin M, progressive destruction of intrahepatic bile ducts, and ultimately liver cirrhosis and failure. Familiarity and high concordance rates for the disease among monozygotic twins strongly support the role of genetics in the disease. Experimental efforts have been dedicated by our and other research groups to investigate the role of X chromosome abnormalities (i.e. monosomyrates and inactivation patterns) in autoimmunity. Our recent work has demonstrated enhanced X monosomy in women with PBC as well as two other female-predominant autoimmune diseases, systemic sclerosis and autoimmune thyroid disease. We will review herein the most recent evidence on the role of the X chromosome in PBC onset and discuss the potential implications. Future developments of these findings will be discussed.

The X Chromosome in Female‐Predominant Autoimmune Diseases

Autoimmune diseases affect approximately 5% of the population in Western countries, with high female predominance. Family and twins studies have demonstrated that genetic factors are crucial determinants of susceptibility to autoimmune disease, but no specific genes have yet been identified. Recent studies indicate that X chromosome abnormalities, such as monosomy rates and inactivation patterns, occur in a number of female-predominant autoimmune diseases. We will review herein the most recent evidence on the role of the X chromosome in loss of tolerance and discuss its potential implications. Future studies will identify the X chromosome regions containing candidate genes for autoimmune susceptibility.

Preferential X chromosome loss but random inactivation characterize primary biliary cirrhosis

Recent work has demonstrated enhanced X monosomy in women with primary biliary cirrhosis (PBC) as well as two other female-predominant autoimmune diseases, systemic sclerosis and autoimmune thyroid disease. To further our understanding of these events, we have investigated the mechanisms of X chromosome loss and X chromosome inactivation (XCI) in 166 women with PBC and 226 rigorously age-matched healthy and liver disease controls. X chromosome analysis and determination of loss pattern was performed by quantitative fluorescent polymerase chain reaction (QF-PCR) with 4 X-linked short tandem repeats. Further definition of the XCI was based on analysis of methylation-sensitive restriction sites. Importantly, in PBC the X chromosome loss occurs not only more frequently but also in a preferential fashion. This observation supports our thesis that the enhanced X monosomy involves only one parentally derived chromosome and is not secondary to a constitutive non random pattern of XCI. In fact, in the presence of monosomy, the lost X chromosome is necessarily the inactive homologue. The finding that the X chromosome loss is preferential suggests the critical involvement of X chromosome gene products in the female predisposition to PBC and also emphasizes the need to determine the parental origin of the maintained chromosome to investigate the role of imprinting.

The X chromosome and systemic sclerosis

Similar to the majority of autoimmune rheumatic diseases, systemic sclerosis is characterized by a striking female predominance superimposed on a predisposing genetic background. At least two genetic mechanisms have been proposed that play a role in susceptibility to systemic sclerosis; firstly the maintenance of immune tolerance via genes on the X chromosomes and, secondly, fetal microchimerism. Based on these lines of evidence, experimental efforts have been most recently dedicated to investigating the role of X chromosome abnormalities (i.e. monosomy rates and inactivation patterns) in autoimmunity. We will review herein the most recent data on the role of the X chromosome in systemic sclerosis onset and discuss the potential implications. Women with systemic sclerosis manifest an enhanced rate of X monosomic cells in peripheral blood compared with healthy age-matched women. Furthermore, a severely skewed X chromosome inactivation pattern is found in women with systemic sclerosis. These observations, reproduced in other female-predominant autoimmune diseases, strongly support the role of the X chromosome in conferring susceptibility to tolerance breakdown and open novel scenarios to emphasize the unknown etiopathogenesis of systemic sclerosis. The implications of these findings will be discussed.

IFN-γ-inducing transcription factor, T-bet is upregulated by estrogen in murine splenocytes: Role of IL-27 but not IL-12

Estrogen is believed to be involved in regulation of the differentiation, survival, or function of diverse immune cells as well as in many autoimmune and inflammatory diseases. However, the mechanisms behind the immunomodulatory effects of estrogen are poorly understood. Previously, we have shown that natural estrogen can upregulate IFN-γ and IFN-γ-mediated-inflammatory events (iNOS, nitric oxide, COX-2). Since IFN-γ is regulated by T-bet, in this study, we investigated whether estrogen induces T-bet expression in primary murine splenocytes. We found that in vivo estrogen treatment primes splenocytes for early upregulation of T-bet upon activation by T cell stimulants, Concanavalin-A (Con-A) or anti-CD3 antibodies. The expression of T-bet protein was not altered by IL-12 while IFN-γ had partial effects on T-bet in splenocytes from estrogen-treated mice. Notably, T-bet expression increased in Con-A-activated splenocytes from estrogen-treated mice in the presence of IL-27. Together, our studies show that in vivo estrogen exposure primes lymphocytes towards Th1 type development by promoting/upregulating T-bet expression, which is upregulated in part by IFN-γ and IL-27. Given that T-bet is a potent inducer of IFN-γ, these studies may lead to new lines of investigation in relation to many female-predominant autoimmune diseases and inflammatory disorders.