S100A8 expression in oviduct mucosal epithelial cells is regulated by estrogen and affects mucosal immune homeostasis.

Chronic inflammation can cause oviduct mucosal damage and immune dysfunction, leading to infertility, early pregnancy loss, ectopic pregnancy, tumors, and a decrease in reproductive capacities in female animals. Estrogen can suppress immune responses in different tissues and oviducts, and regulate the oviduct immune balance; however, the underlying mechanisms remain unclear. The objective of this study was to explore the mechanism of estrogen-regulated oviduct mucosal immunity and discover new estrogen targets for regulating oviduct mucosal immune homeostasis. Sheep oviduct epithelial cells (SOECs) were treated with 17-ß estradiol (E2). Transcriptome sequencing and analysis showed differentially expressed S100 calcium-binding protein A (S100A) genes that may participate in the oviduct mucosa immunoregulation of estrogen. Quantitative polymerase chain reaction and immunocytochemistry analysis showed that S100A8 expression changed dynamically in E2-treated SOECs and peaked after 7 h of treatment. Estrogen nuclear receptors and G protein-coupled membrane receptors promoted E2-dependent S100A8 upregulation. The S100A8 gene was disrupted using the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 method. Levels of inflammatory factors interleukin (IL)-1ß and IL-4 were significantly upregulated in S100A8-knockdown SOECs, whereas those of the anti-inflammatory factor IL-10 was downregulated. Following S100A8 knockdown in SOECs treated with E2 for 7 h, IL-10 levels increased significantly. Estrogen affected oviduct mucosa immune function and dynamically regulated S100A8 in SOECs. S100A8 knockdown caused an excessive immune response, indicating that S100A8 is beneficial for maintaining immune homeostasis in the oviduct mucosa. Moreover, estrogen can compensate for the effect of S100A8 knockdown by upregulating IL-10.

The role of estradiol in the immune response against COVID-19.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is the pathogen agent causing coronavirus disease (COVID)-19, which was declared a global pandemic in 2020. The spike protein of this virus and the angiotensin-converter enzyme (ACE)-2 in host cells in humans play a vital role in infection and in COVID-19 pathogenesis. Estradiol is known to modulate the actions of immune cells, and, therefore, the antiviral mechanisms of these cells could also be modified by this hormone stimulus. Even though estradiol is not considered a protective factor, evidence shows that women with high levels of this hormone have a lower risk of developing severe symptoms and an even a lower incidence of death. Understanding the mechanism of action of estradiol with regard to viral infections and COVID-19 is essential for the improvement of therapeutic strategies. This review aims to describe the effects that estradiol exerts on immune cells during viral infections and COVID-19.

Follicle stimulating hormone and estradiol alter immune response in osteoarthritic mice in an opposite manner.

Although a number of studies have shown that the occurrence and progression of osteoarthritis (OA) is related to endocrine system dysfunction, there is limited evidence about what roles sex hormones play. The aim of the present study was to examine the capacity of 17ß-estradiol (ED) and follicle stimulating hormone (FSH) to alter the differentiation of bone marrow (BM) cells in arthritic mice. The experiments were conducted in collagenase-induced osteoarthritis in mice. Cartilage degradation was observed by safranin and toluidine blue staining. Flow cytometry was used to define different BM and synovial cell populations. The influence of FSH and ED on osteoclastogenesis was studied in BM cultures and on the osteoblastogenesis in primary calvarial cultures. The levels of IL-8, TNF-α, FSH, and osteocalcin were estimated by ELISA. FSH increased cartilage degradation and serum osteocalcin levels, while ED abolished it and lowered serum osteocalcin. FSH elevated the percentage of monocytoid CD14+/RANK+ and B cell CD19+/RANK+ cells in contrast to ED which inhibited the accumulation of these osteogenic populations. Also, ED changed the percentage of CD105+/F4/80+ and CD11c+ cells in the synovium. FSH augmented and ED suppressed macrophage colony-stimulating factor (M-CSF) + receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast (OC) formation, and this correlated with a respective increase and decrease of IL-8 secretion. FSH did not influence osteoblast (OB) formation while ED enhanced this process in association with changes of TNF-α, IL-8, and osteocalcin production. ED reduced osteoclast generation in bone. The key outcome of the current study is that both hormones influenced BM cell differentiation, with FSH favoring osteoclast formation and ED favoring osteoblast accumulation.

Supraphysiological estradiol promotes human T follicular helper cell differentiation and favours humoural immunity during in vitro fertilization.

During pregnancy, humoural immunity is essential for protection against many extracellular pathogens; however, autoimmune diseases may be induced or aggravated. T follicular helper (Tfh) cells contribute to humoural immunity. The aim of this study was to test whether Tfh cell function can be manipulated via hormones. Seventy-four women who underwent in vitro fertilization were recruited and divided into four groups: menstrual period (MP), controlled ovarian hyperstimulation (COH), embryo transfer (ET) and pregnant after embryo transfer (P). A flow cytometry analysis was performed to identify Tfh cells in peripheral blood mononuclear cells (PBMCs). Bioinformatics analysis revealed a possible pathway between Tfh and B cells. Enzyme-linked immunosorbent assays were used to detect interleukin (IL)-21 and IL-6. The quantitative polymerase chain reaction was performed to quantify BCL-6, BACH2, XBP-1, IRF-4 and G protein-coupled (GP)ER-1 mRNA expression. Compared with the MP group, the COH, ET and P groups showed more Tfh and B cells, as well as higher IL-21, IL-6, BCL-6 and BACH2 expression. Furthermore, Tfh cell frequency in PBMCs, as well as serum IL-21 and IL-6 levels, were all positively correlated with serum estradiol (E2 ) levels; the B cell percentage also correlated positively with Tfh cells in PBMCs. Combined with the bioinformatics analysis, XBP-1, IRF-4 and GPER-1 expression was related to E2 levels, both in vivo and in vitro. We speculate that E2 augments Tfh cells and favours humoural immunity. This study indicates that Tfh cell regulation may be a novel target in maintaining the maternal-foetal immune balance.

Human pregnancy levels of estrogen and progesterone contribute to humoral immunity by activating TFH /B cell axis.

Circulating TFH (cTFH ) cells express CXCR5, PD-1, and, when activated, ICOS, and release IL-21. According to the production of IFN-γ, IL-4, and IL-17 and expression of FoxP3, these cells are also classified as cTFH 1, cTFH 2, cTFH 17, and cTFR cells, respectively. This CD4+ T-cell subset is pivotal to efficient humoral immunity, and pregnancy appears to favor IgG production. Here, not only pregnancy amplified the in vivo production of anti-HBsAg IgG in HBV immunized women, but the frequency of cTFH cells was directly correlated with estradiol levels. In vitro, pregnancy-related dose of 17-ß-estradiol (E2) directly increased the percentage of different cTFH subsets. While E2 and progesterone (P4) increased the proportion of differentiated TFH cells derived from naïve CD4+ T-cells, only E2 amplified the release of IL-21 in those cell cultures. In addition, E2 and P4 increased the proportion of memory B cells and plasma cells, respectively. In SEB-activated B/TFH cell co-cultures, E2, in the presence of P4, increased the production of total IgG. Finally, among the hormones, P4 was stronger in upregulating the percentage of IL-10+ TFR cells. Collectively, our findings suggested that E2 and P4 cooperate in the humoral immune response by favoring the expansion of different cTFH and B cell subsets.

Sex and COVID-19: A Protective Role for Reproductive Steroids.

Evidence shows coronavirus disease 2019 (COVID-19)-induced symptom severity and mortality is more frequent in men than in women, suggesting sex steroids may play a protective role. Female reproductive steroids, estrogen and progesterone, and its metabolite allopregnanolone, are anti-inflammatory, reshape competence of immune cells, stimulate antibody production, and promote proliferation and repair of respiratory epithelial cells, suggesting they may protect against COVID-19 symptoms.

Level of sex hormones and their association with acetylsalicylic acid intolerance and nasal polyposis.

BACKGROUND: Chronic rhinosinusitis may be associated with nasal polyposis. Recurrence of disease is often observed and may be due to an intolerance of acetylsalicylic acid. Sex hormones are known to modulate allergic reactions and inflammation. Whether they may be involved in the development and progression of nasal polyposis has not been investigated yet. AIM: Examine the relationship between levels of sex hormones and nasal polyposis. METHODS: Hormonal levels (estradiol, testosterone and progesterone) in patients with nasal polyposis (n = 26) with or without acetylsalicylic acid-intolerance were determined and compared to hormonal levels in patients with septal deviation (n = 35). Cone-beam computed tomography scans were analysed by using scores as defined by Lund and Mackay and by Kennedy. RESULTS: Our results show a 5 times greater odds (p = 0.01) for developing nasal polyposis in the presence of lowered estradiol plasma levels than in the presence of normal / elevated levels. When analyzing females and males separately, a 6 times greater odds for females to develop nasal polyposis in the presence of lowered estradiol plasma levels was calculated (p = 0.02). Thus, females are more likely to develop nasal polyposis when they have lowered estradiol levels than males. In addition, female patients showed an increased risk for developing ASA intolerance (p = 0.01). CONCLUSION: Variation of sex hormones may be involved in nasal polyposis. Further studies including more patients to validate the presented results are required. SIGNIFICANCE: Retrospective clinical investigation suggesting a correlation between varying sex hormones and nasal polyposis.

Estradiol Enhances Antiviral CD4+ Tissue-Resident Memory T Cell Responses following Mucosal Herpes Simplex Virus 2 Vaccination through an IL-17-Mediated Pathway.

Estradiol (E2) is a sex hormone which has been shown to be protective against sexually transmitted infections such as herpes simplex virus 2 (HSV-2). However, few studies have examined the underlying mechanisms by which this occurs. Here, we investigated the effect of E2 on the establishment of memory T cells post-intranasal immunization with HSV-2. CD4+ T cell responses first appeared in the upper respiratory tract (URT) within 3 days postimmunization before being detected in the female reproductive tract (FRT) at 7 days. E2 treatment resulted in greater and earlier Th17 responses, which preceded augmented Th1 responses at these sites. The CD4+ T cells persisted in the URT for up to 28 days, and E2 treatment resulted in higher frequencies of memory T cells. Intranasal immunization also led to the establishment of CD4+ tissue-resident memory T cells (TRM cells) in the FRT, and E2 treatment resulted in increased Th1 and Th17 TRM cells. When the migration of circulating T cells into the FRT was blocked by FTY720, immunized E2-treated mice remained completely protected against subsequent genital HSV-2 challenge compared to non-E2 controls, confirming that TRM cells alone are adequate for protection in these mice. Finally, the enhanced vaginal Th1 TRM cells present in E2-treated mice were found to be modulated through an interleukin 17 (IL-17)-mediated pathway, as E2-treated IL-17A-deficient mice had impaired establishment of Th1 TRM cells. This study describes a novel role for E2 in enhancing CD4+ memory T cells and provides insight on potential strategies for generating optimal immunity during vaccination.IMPORTANCE Herpes simplex virus 2 (HSV-2) is a highly prevalent sexually transmitted infection for which there is currently no vaccine available. Interestingly, the female sex hormone estradiol has been shown to be protective against HSV-2. However, the underlying mechanisms by which this occurs remains relatively unknown. Our study demonstrates that under the influence of estradiol treatment, intranasal immunization with an attenuated strain of HSV-2 leads to enhanced establishment of antiviral memory T cell responses in the upper respiratory tract and female reproductive tract. In these sites, estradiol treatment leads to greater Th17 memory cells, which precede enhanced Th1 memory responses. Consequently, the T cell responses mounted by tissue-resident memory cells in the female reproductive tract of estradiol-treated mice are sufficient to protect mice against vaginal HSV-2 challenge. This study offers important insights regarding the regulation of mucosal immunity by hormones and on potential strategies for generating optimal immunity during vaccination.

Estradiol, Progesterone, Immunomodulation, and COVID-19 Outcomes.

Severe outcomes and death from the novel coronavirus disease 2019 (COVID-19) appear to be characterized by an exaggerated immune response with hypercytokinemia leading to inflammatory infiltration of the lungs and acute respiratory distress syndrome. Risk of severe COVID-19 outcomes is consistently lower in women than men worldwide, suggesting that female biological sex is instrumental in protection. This mini-review discusses the immunomodulatory and anti-inflammatory actions of high physiological concentrations of the steroids 17ß-estradiol (E2) and progesterone (P4). We review how E2 and P4 favor a state of decreased innate immune inflammatory response while enhancing immune tolerance and antibody production. We discuss how the combination of E2 and P4 may improve the immune dysregulation that leads to the COVID-19 cytokine storm. It is intended to stimulate novel consideration of the biological forces that are protective in women compared to men, and to therapeutically harness these factors to mitigate COVID-19 morbidity and mortality.

Age-associated decline in neural, endocrine, and immune responses in men and women: Involvement of intracellular signaling pathways.

The aim of this study was to investigate the alterations in the neuroendocrine-immune functions by using human peripheral blood mononuclear cells (hPBMCs) from three age groups (young, middle-aged, and old) of men and women for the analyses of lymphocyte proliferation and cytokine production, expression of cell signaling molecules, nitric oxide (NO) production, and expression of p-tyrosine hydroxylase (TH). Serum was examined for levels of testosterone in men, 17-ß-estradiol in women, and cortisol in both sexes. Lymphoproliferation, expression of p-ERK, p-CREB, p-Akt, and p-TH, and levels of serum sex steroid hormones declined with age in men and women. However, TNF-α production and serum cortisol level increased with age in men and women. mTOR expression was higher in older men while it was lower in older women. IFN-γ and IL-6 production and expression of p-TH and p-mTOR were differentially regulated in men and women. These results suggest that intracellular signaling mediators may be involved in the age-related alterations in the neuroendocrine-immune interactions in men and women.

[Autoimmune markers for non-invasive diagnosis of endometriosis in women]. / Autoimmunnye markery dlia neinvazivnoi diagnostiki éndometrioza u zhenshchin.

Endometriosis is a common estrogen-dependent chronic disease in women of reproductive age; it is associated with dysregulation of the immune response, local inflammation, and increased formation of autoantibodies. The aim of the study was to investigate the profile of autoantibodies in women with endometriosis and to evaluate their diagnostic value using new modifications of enzyme immunoassay. In women with endometriosis of stage III-IV (n=39), a wide spectrum of autoantibodies was detected, mainly of class G, including antibodies to endometrial antigens (tropomyosin 3, tropomodulin 3), the enzyme α-enolase, steroid (estradiol, progesterone) and gonadotropic hormones. At the same time, the frequency of detection of IgG antibodies to tropomyosin 3, α-enolase, estradiol and human chorionic gonadotropin and their levels in patients with endometriosis were higher than in healthy women (n=26) (p<0.05). IgG-antibodies to tropomyosin 3, α-enolase and estradiol were characterized by higher diagnostic value for endometriosis. The diagnostic value was significantly increased when these antibodies were combined: the AUC reached 0.875 [0.772-0.978] (p<0.0001), the sensitivity and specificity were 83.3% each. Thus, autoantibodies to tropomyosin 3, α-enolase, and estradiol are promising for inclusion in the panel of biomarkers for non-invasive diagnosis of endometriosis.

Seeking high-priority mutations enabling successful antibody-breeding: systematic analysis of a mutant that gained over 100-fold enhanced affinity.

"Antibody-breeding" has provided therapeutic/diagnostic antibody mutants with greater performance than native antibodies. Typically, random point mutations are introduced into the VH and VL domains of parent antibodies to generate diverse libraries of single-chain Fv fragments (scFvs), from which evolved mutants are selected. We produced an scFv against estradiol-17ß with 11 amino acid substitutions and a >100-fold improved affinity constant (Ka = 1.19 × 1010 M-1) over the parent scFv, enabling immunoassays with >30-fold higher sensitivity. We systematically analyzed contributions of these substitutions to the affinity enhancement. Comparing various partial scFv revertants based on their Kas indicated that a revertant with four substitutions (VH-L100gQ, VL-I29V, -L36M, -S77G) exhibited somewhat higher affinity (Ka = 1.46 × 1010 M-1). Finally, the VH-L100gQ substitution, occurring in VH complementarity-determining region (CDR) 3, was found to be the highest-priority for improving the affinity, and VL-I29V and/or VL-L36M cooperated significantly. These findings encouraged us to reconsider the potential of VH-CDR3-targeting mutagenesis, which has been frequently attempted. The substitution(s) wherein might enable a "high rate of return" in terms of selecting mutants with dramatically enhanced affinities. The "high risk" of generating a tremendous excess of "junk mutants" can be overcome with the efficient selection systems that we developed.

Establishment of an immunofiltration strip for the detection of 17ß-estradiol based on the photothermal effect of black phosphorescence.

Recently, the photothermal effect of nanomaterials has opened the door for new appealing strategy, which can generate a promising and powerful tool when combined with immunoassay. As a new kind of nanomaterial, black phosphorus (BP) has aroused widespread interest. In this study, a novel immunofiltration strip method with temperature as the readout signal based on the photothermal effect of BP nanosheets was established. The temperature was monitored by a portable temperature sensor. Using an indirect competitive strategy, it provides a simple, rapid, sensitive, and economic platform for the detection of 17ß-estradiol, a kind of endocrine disrupting compound that is frequently detected in environmental water or food samples. The higher the concentration of 17ß-estradiol in the sample, the less BP nanosheets are brought to bind to the strip surface, along with lower temperature variation when exposed to intensive laser irradiation. Under optimum conditions, a detection limit of 0.104 ng mL-1 was achieved. The feasibility of this assay was assessed by a standard addition method in water and milk samples, showing good performance and indicating potential application value for easy-to-use, inexpensive, and on-site monitoring of 17ß-estradiol.

Impact of conjugation strategies for targeting of antibodies in gold nanoparticles for ultrasensitive detection of 17ß-estradiol.

Antibody-coated nanoparticles have recently attracted considerable attention, with the focus falling on diagnostics. Nevertheless, controlled antibody bioconjugation remains a challenge. Here, we present two strategies of bioconjugation with the aim of evaluating the best approach for the coupling of antibodies on the surface of nanomaterials in an oriented way. We employed electrostatic interaction (physical adsorption) and covalent conjugation in the orientation of antibodies on the metallic surface as coupling methods, and their influence on the detection of 17ß-estradiol was addressed with localized surface plasmon resonance. The understanding of these mechanisms is fundamental for the development of reproducible inorganic bioconjugates with oriented surface as well sensibility of immunoassays.

Testosterone is positively and estradiol negatively associated with mucosal immunity in Amazonian adolescents.

OBJECTIVES: A core assumption of life history theory and the immunocompetence handicap hypothesis (ICHH) is that testosterone (T) upregulates energetic investment in mating effort at the expense of immunity. This tenet, along with observed positive relationships between estrogens and immunity, may contribute to the higher observed morbidity and mortality of males. In the present study, we examine the association between sex steroid hormones and mucosal immunity as well as sex differences in immunity in a rural Amazonian population of immune-challenged Bolivian adolescents. METHODS: Salivary steroid hormones (T [males only] and estradiol [E2 , females only]), Tsimane-specific age-standardized BMI z-scores, and salivary mucosal immunity (sIgA, secretory IgA) were measured in 89 adolescent males and females. RESULTS: Males had significantly higher sIgA levels than females, which may be due to the observed immune-endocrine associations found in the present study. Controlling for age and phenotypic condition, higher T significantly predicted higher sIgA; whereas higher E2 was associated with lower sIgA in females. CONCLUSIONS: Results stood in contrast to common interpretations of the ICHH, that is, that T should be inversely associated with immunity. Findings from the present study support the notion that the endocrine system likely affects immunity in a regulatory fashion, upregulating certain aspects of immunity while downregulating others. An important remaining question is the adaptive reason(s) for sex differences in endocrine-mediated immuno-redistribution.

IL-17 Production by γδ+ T Cells Is Critical for Inducing Th17 Responses in the Female Genital Tract and Regulated by Estradiol and Microbiota.

IL-17 can be produced by adaptive immune cells such as Th17 cells and by immune cells that produce IL-17 without prior priming. This latter category, which we will refer to as "innate," includes innate cells such as NK cells and innate lymphoid cells and innate-like T cell populations such as NKT cells and γδ+ T cells. Studies in mucosal tissues have shown that the induction of Th17 immunity is amplified by innate IL-17 produced within those tissues. However, the role of innate IL-17 and its effect on Th17 induction in the female genital tract (FGT) is largely unknown. In this study, we characterize the primary source of IL-17-secreting vaginal cells and show that innate IL-17 plays a critical role in priming adaptive Th17 responses in the FGT. Under homeostatic conditions, γδ+ T cells were the predominant source of innate IL-17 in the murine FGT, and this population was modulated by both the sex hormone estradiol and the presence of commensal microbiota. Compared with wild-type C57BL/6 mice, vaginal APCs isolated from IL-17A-deficient (IL-17A-/- ) mice were severely impaired at priming Th17 responses in APC-T cell cocultures. Furthermore, the defect in Th17 induction in the absence of innate IL-17 was associated with impairment of IL-1ß production by vaginal CD11c+ dendritic cells. Overall, our study describes a novel role for IL-17 in the FGT and further demonstrates the importance of factors in the vaginal microenvironment that can influence adaptive immune responses.

Development of anti-immunocomplex specific antibodies and non-competitive time-resolved fluorescence immunoassay for the detection of estradiol.

Detection of circulatory estradiol has widespread use in various clinical applications. Particularly, the use of estradiol-specific antibodies in immunoassays is routinely used, mainly due to the cost efficiency and simplicity of the sample handling process. However, the circulatory levels of estradiol can be extremely low in some conditions, and beyond the current detection limit of existing competitive immunoassays. We describe the generation of anti-immunocomplex specific antibodies derived from synthetic antibody repertoire and the development of high-performance non-competitive immunoassay for the detection of estradiol. Phage display selections were used to isolate new antibodies from synthetic antibody library with the use of existing estradiol specific Fab fragment. The found antibodies were consecutively used to set up a time-resolved fluorescence-based immunoassay (TRFIA), which can be used to detect estradiol with exceptional sensitivity and specificity. The limit of detection and EC50 were shown to be 3.0 pg mL-1 and 32.4 pg mL-1 respectively. Graphical abstract.

Surface plasmon resonance based indirect immunoassay for detection of 17ß-estradiol.

A surface plasmon resonance (SPR) based immunosensor is presented for highly sensitive and selective detection of 17ß-estradiol by the indirect competitive inhibition immuno assay, employing anti-17 ß-estradiol antibody as high molecular weight (HMW) interactant. Immobilization of estradiol-BSA conjugate onto the nano thin gold surface was accomplished by covalent amide linkage through self assembled monolayer. The proposed biosensor is simple to fabricate, reproducible and exhibit excellent sensitivity for estrogen (detection limit,1 pg mL-1) without any significant interference from structurally similar steroidal hormone, progesterone and non-steroidal compound bisphenol-A. The proposed surface displayed a high level of stability during repeated regeneration and immunoreaction cycles suitable for biosensor development.

Disruptions in the reproductive system of female rats after prenatal lipopolysaccharide-induced immunological stress: role of sex steroids.

Stress signals during fetal or early postnatal periods may disorganize reproductive axis development at different levels. This study was aimed to test the hypothesis that prenatal immunological stress induced by bacterial endotoxin, lipopolysaccharide (LPS), has impact on structure and function of the reproductive system in female offspring. Adult female Wistar rats were divided into two groups, a control group (n = 5) and a LPS group (n = 12). Rats were injected with LPS 50 µg/kg body or 0.9% saline intraperitoneally on the 12th day of pregnancy. After birth the female pups (n = 20 in each group) were divided into four groups: (group 1) 0.9% saline prenatally, sesame oil (vehicle) postnatally; (group 2) LPS prenatally, sesame oil postnatally; (group 3) LPS prenatally, fulvestrant postnatally; (group 4) LPS prenatally, flutamide postnatally. Pups were injected subcutaneously into the neck with fulvestrant (estrogen receptor antagonist), 1.5 mg/kg in sesame oil, from postnatal day (PND) 5 to PND14; or flutamide (androgen receptor antagonist), 20 mg/kg in sesame oil, from PND14 to PND30. Rats of the control group were injected with sesame oil during the same time period. Parameters were evaluated by ELISA (serum estradiol and testosterone) and ovarian histology. The main findings were: (1) prenatal stress during the critical period resulted in delayed vaginal opening, decreased body weight and serum concentrations of sex steroids, and significant disorders in ovarian development; (2) postnatal estradiol and testosterone antagonist treatments decreased follicular atresia through increasing the number of healthy follicles and restored endogenous steroid production. Lay summaryImmunological stress, caused by simulating infection through exposure to a bacterial toxin (LPS), during a critical period of fetal development in laboratory rats results in delayed reproductive maturity, decreased body weight and decreased secretion of sex steroids in female offspring, and abnormalities in the ovaries like those in polycystic ovarian syndrome. These prenatally toxin-induced sexual disorders in females could be corrected by estradiol/testosterone antagonists during the postnatal period.

The Role of Interleukin-10 in Mediating the Effect of Immune Challenge on Mouse Gonadotropin-Releasing Hormone Neurons In Vivo.

Immune challenge alters neural functioning via cytokine production. Inflammation has profound impact on the central regulation of fertility, but the mechanisms involved are not clearly defined. The anti-inflammatory cytokine interleukin (IL)-10 is responsible for balancing the immune response in the brain. To examine whether IL-10 has an effect on the function of the gonadotropin-releasing hormone (GnRH) neurons, we first examined the effect of immune responses with distinct cytokine profiles, such as the T cell-dependent (TD) and T cell-independent (TI) B-cell response. We investigated the effect of the TD and TI immune responses on ERK1/2 phosphorylation in GnRH neurons by administering fluorescein isothiocyanate/keyhole limpet hemocyanin (KLH-FITC) or dextran-FITC to female mice. Although dextran-FITC had no effect, KLH-FITC induced ERK1/2 phosphorylation in GnRH neurons after 6 d. KLH-FITC treatment increased the levels of IL-10 in the hypothalamus (HYP), but this treatment did not cause lymphocyte infiltration or an increase in the levels of proinflammatory cytokines. In IL-10 knock-out (KO) mice, KLH-FITC-induced ERK1/2 phosphorylation in the GnRH neurons was absent. We also showed that in IL-10 KO mice, the estrous cycle was disrupted. Perforated patch-clamp recordings from GnRH-GFP neurons, IL-10 immunohistochemistry, and in vitro experiments on acute brain slices revealed that IL-10 can directly alter GnRH neuron firing and induce ERK1/2 phosphorylation. These observations demonstrate that IL-10 plays a role in influencing signaling of GnRH neurons in the TD immune response. These results also provide the first evidence that IL-10 can directly alter the function of GnRH neurons and may help the maintenance of the integrity of the estrous cycle.