Differential modulation of TLR3- and TLR4-mediated dendritic cell maturation and function by progesterone

The impact of reproductive hormones on T cell immunity; normal and assisted reproductive cycles

During pregnancy, a unique immune milieu is established systemically and locally at the maternal-fetal interface. While preparing for embryonic implantation, endometrial effectors significantly change their proportions and function, which are synchronized with hormonal changes. During assisted reproductive technology cycles, various cytokines, chemokines, and immune factors dynamically change with the altered receptor expressions on the immune effectors. Thus, the hormonal regulation of immune effectors is critical to maintaining the immune milieu. In this review, hormonal effects on T cell subsets are reviewed. Sex hormones affect T cell ontogeny and development, consequently affecting their functions. Like other T cell subsets, CD4+ T helper (Th) cells are modulated by estrogen, where low estrogen concentration promotes Th1-driven cell-mediated immunity in the uterus and in vitro by enhancing IFN-γ production, while a high estrogen level decreases it. The abundance and differentiation of T regulatory (Treg) cells are controlled by estrogen, inducing Treg expansion. Conversely, progesterone maintains immune homeostasis by balancing Th1/Th2 and Th17/Treg immunity, leading to maternal-fetal tolerance. Therefore, the understanding of the hormonal impact on various T cell subsets during the reproductive cycles is critical to improving reproductive outcomes in women with recurrent pregnancy losses, repeated implantation failures, and undergoing assisted reproductive cycles.

In Situ Array Microextraction and Metabolic Profiling of Small Extracellular Vesicles to Guide and Monitor Maternal Delivery

The advantages of small extracellular vesicles (sEV) in disease management have become increasingly prominent, with the main challenge lying in meeting the demands of large-scale extraction and high-throughput analysis, a crucial aspect in the realm of precision medicine. To overcome this challenge, an engineered on-plate aptamer array (16×24 spots) is developed for continuous scale-up microextraction of plasma sEV and their in situ metabolic analysis using mass spectrometry. With this integrated array strategy, metabolic profiles of sEV are acquired from the plasma of 274 antenatal or postpartum women, reducing analysis time by half (7.5 h) and sample volume by 95% (only 0.125 µL usage) compared to the traditional suspension method. Moreover, using machine learning algorithms on sEV metabolic profiles, a risk score system is constructed that accurately assesses the need for epidural analgesia during childbirth and the likelihood of post-administration fever. The system, based on admission samples, achieves an impressive 94% accuracy. Furthermore, post-administration fever can be identified from delivery samples, reaching an overall accuracy rate of 88%. This work offers real-time monitoring of the childbirth process that can provide timely guidance for maternal delivery, underscoring the significance of sEV detection in large-scale clinical samples for medicine innovation and advancement.

Hallmarks of sex bias in immuno-oncology: mechanisms and therapeutic implications

Sex differences are present across multiple non-reproductive organ cancers, with male individuals generally experiencing higher incidence of cancer with poorer outcomes. Although some mechanisms underlying these differences are emerging, the immunological basis is not well understood. Observations from clinical trials also suggest a sex bias in conventional immunotherapies with male individuals experiencing a more favourable response and female individuals experiencing more severe adverse events to immune checkpoint blockade. In this Perspective article, we summarize the major biological hallmarks underlying sex bias in immuno-oncology. We focus on signalling from sex hormones and chromosome-encoded gene products, along with sex hormone-independent and chromosome-independent epigenetic mechanisms in tumour and immune cells such as myeloid cells and T cells. Finally, we highlight opportunities for future studies on sex differences that integrate sex hormones and chromosomes and other emerging cancer hallmarks such as ageing and the microbiome to provide a more comprehensive view of how sex differences underlie the response in cancer that can be leveraged for more effective immuno-oncology approaches.

Diagnostic tests for progestogen hypersensitivity

Progesterone is an endogenous hormone, produced by the adrenal cortex, the gonads and in women, its source is the corpus luteum. Progesterone is produced in the late phase of the menstrual cycle, when implantation of the zygote does not occur, the corpus luteum involutes and the release of progesterone is suppressed, thus initiating menstruation. Progestogen Hypersensitivity were initially identified as hormone allergy and were related to endogenous reactions to hormones and alteration of ovarian function. Skin manifestations such as dermatitis or urticaria were initially reported and described as progesterone autoimmune dermatitis, although the immune-mediated mechanism was not clear. Currently there is no standardization for in vivo or in vitro tests for Progestogen Hypersensitivity diagnosis. In this review, we will address the different diagnostic methods of this disease.

Immune Cells, Gut Microbiota, and Vaccines: A Gender Perspective

The development of preventive and therapeutic vaccines has played a crucial role in preventing infections and treating chronic and non-communicable diseases, respectively. For a long time, the influence of sex differences on modifying health and disease has not been addressed in clinical and preclinical studies. The interaction of genetic, epigenetic, and hormonal factors plays a role in the sex-related differences in the epidemiology of diseases, clinical manifestations, and the response to treatment. Moreover, sex is one of the leading factors influencing the gut microbiota composition, which could further explain the different predisposition to diseases in men and women. In the same way, differences between sexes occur also in the immune response to vaccines. This narrative review aims to highlight these differences, focusing on the immune response to vaccines. Comparative data about immune responses, vaccine effectiveness, and side effects are reviewed. Hence, the intricate interplay between sex, immunity, and the gut microbiota will be discussed for its potential role in the response to vaccination. Embracing a sex-oriented perspective in research may improve the efficacy of the immune response and allow the design of tailored vaccine schedules.

Bovine serum albumin nanoparticles containing Poly (I:C) can enhance the neutralizing antibody response induced by envelope protein of Orthoflavivirus zikaense

Since the Orthoflavivirus zikaense (ZIKV) has been considered a risk for Zika congenital syndrome development, developing a safe and effective vaccine has become a high priority. Numerous research groups have developed strategies to prevent ZIKV infection and have identified the domain III of the ZIKV envelope protein (zEDIII) as a promising target. Subunit antigens are often poorly immunogenic, necessitating the use of adjuvants and/or delivery systems to induce optimal immune responses. The subject of nanotechnology has substantial expansion in recent years in terms of research and applications. Nanoparticles could be used as drug delivery systems and to increase the immunogenicity and stability of a given antigen. This work aims to characterize and validate the potential of a vaccine formulation composed of domain zEDIII and bovine serum albumin nanoparticles containing polyinosinic-polycytidylic acid (NPPI). NPPI were uptake in vitro by immature bone marrow dendritic cells and histological analysis of the skin of mice treated with NPPI showed an increase in cellularity. Immunization assay showed that mice immunized with zEDIII in the presence of NPPI produced neutralizing antibodies. Through the passive transfer of sera from immunized mice to ZIKV-infected neonatal mice, it was demonstrated that these antibodies provide protection, mitigating weight loss, clinical or neurological signs induced by infection, and significantly increased survival rates. Protection was further substantiated by the reduction in the number of viable infectious ZIKV, as well as a decrease in inflammatory cytokines and tissue alterations in the brains of infected mice. Taken together, data presented in this study shows that NPPI + zEDIII is a promising vaccine candidate for ZIKV.

Battle Within the Sexes: Differences in Male and Female Immunity and the Impact on Antitumor Responses

The immune system plays critical roles in regulating tumor progression. However, despite established differences in male and female immune cell function, our appreciation of sex as a variable in antitumor immune responses is only beginning to develop. Recent findings in mice have demonstrated for the first time that disparities in cancer incidence between the sexes are driven in part by differences in male and female T-cell responses. This review will discuss the growing body of literature demonstrating that male and female innate and adaptive immune responses against tumors are not equivalent and highlight the impact this may have on tumor responses to immunotherapies.

Sex dimorphism and cancer immunotherapy: May pregnancy solve the puzzle?

In the immunoncology era, growing evidence has shown a clear sex dimorphism in antitumor immune response with a potential impact on outcomes upon immunecheckpoint blockade (ICI) in patients with cancer. Sex dimorphism could affect tumor microenvironment composition and systemic anticancer immunity; however, the modifications induced by sex are heterogeneous. From a clinical perspective, six metanalyses have explored the role of sex in cancer patients receiving ICI with conflicting results. Environmental and reproductive factors may further jeopardize the sex-related heterogeneity in anticancer immune response. In particular, pregnancy is characterized by orchestrated changes in the immune system, some of which could be long lasting. A persistence of memory T-cells with a potential fetal-antigen specificity has been reported both in human and mice, suggesting that a previous pregnancy may positively impact cancer development or response to ICI, in case of fetal-antigen sharing from tumor cells. On the other hand, a previous pregnancy may also be associated with a regulatory memory characterized by increased tolerance and anergy towards cancer-fetal common antigens. Finally, fetal-maternal microchimerism could represent an additional source of chronic exposure to fetal antigens and may have important immunological implications on cancer development and ICI activity. So far, the role of pregnancy dimorphism (nulliparous vs parous) in women and the impact of pregnancy-related variables remain largely underexplored in cancer patients. In this review, we summarize the evidence regarding sex and pregnancy dimorphism in the context of immune response and anticancer immunotherapy and advocate the importance of analyzing pregnancy variables on ICIs clinical trials.

Sex hormone signaling and regulation of immune function

Immune responses to antigens, including innocuous, self, tumor, microbial, and vaccine antigens, differ between males and females. The quest to uncover the mechanisms for biological sex differences in the immune system has intensified, with considerable literature pointing toward sex hormonal influences on immune cell function. Sex steroids, including estrogens, androgens, and progestins, have profound effects on immune function. As such, drastic changes in sex steroid concentrations that occur with aging (e.g., after puberty or during the menopause transition) or pregnancy impact immune responses and the pathogenesis of immune-related diseases. The effect of sex steroids on immunity involves both the concentration of the ligand and the density and distribution of genomic and nongenomic receptors that serve as transcriptional regulators of immune cellular responses to affect autoimmunity, allergy, infectious diseases, cancers, and responses to vaccines. The next frontier will be harnessing these effects of sex steroids to improve therapeutic outcomes.

Crosstalk between reproductive and immune systems: the teleostean perspective

The bidirectional interaction between the hypothalamic-pituitary-gonadal (HPG) axis and the immune system plays a crucial role in the adaptation of an organism to its environment, its survival and the continuance of a species. Nonetheless, very little is known about this interaction among teleost, the largest group of extant vertebrates. Fishes being seasonal breeders, their immune system is exposed to seasonally changing levels of HPG hormones. On the contrary, the presence and infiltration of leukocytes, the expression of pattern recognition receptors as well as cytokines in gonads suggest their key role in teleostean gametogenesis as in the case of mammals. Moreover, the modulation of gametogenesis and steroidogenesis by lipopolysaccharide implicates the pathological significance of inflammation on reproduction. Thus, it is important to engage in the understanding of the interaction between these two important physiological systems, not only from a phylogenetic perspective but also due to the importance of fish as an important economic resource. In view of this, the authors have reviewed the crosstalk between the reproductive and immune systems in teleosts and tried to explore the importance of this interaction in their survival and reproductive fitness.

Biological Sex and Pregnancy Affect Influenza Pathogenesis and Vaccination

Males and females differ in the outcome of influenza A virus (IAV) infections, which depends significantly on age. During seasonal influenza epidemics, young children (< 5 years of age) and aged adults (65+ years of age) are at greatest risk for severe disease, and among these age groups, males tend to suffer a worse outcome from IAV infection than females. Following infection with pandemic strains of IAVs, females of reproductive ages (i.e., 15-49 years of age) experience a worse outcome than their male counterparts. Although females of reproductive ages experience worse outcomes from IAV infection, females typically have greater immune responses to influenza vaccination as compared with males. Among females of reproductive ages, pregnancy is one factor linked to an increased risk of severe outcome of influenza. Small animal models of influenza virus infection and vaccination illustrate that immune responses and repair of damaged tissue following IAV infection also differ between the sexes and impact the outcome of infection. There is growing evidence that sex steroid hormones, including estrogens, progesterone, and testosterone, directly impact immune responses during IAV infection and vaccination. Greater consideration of the combined effects of sex and age as biological variables in epidemiological, clinical, and animal studies of influenza pathogenesis is needed.

Sex—the most underappreciated variable in research: insights from helminth-infected hosts

The sex of a host affects the intensity, prevalence, and severity of helminth infection. In many cases, one sex has been found to be more susceptible than the other, with the prevalence and intensity of helminth infections being generally higher among male than female hosts; however, many exceptions exist. This observed sex bias in parasitism results primarily from ecological, behavioural, and physiological differences between males and females. Complex interactions between these influences modulate the risk of infection. Indeed, an interplay among sex hormones, sex chromosomes, the microbiome and the immune system significantly contributes to the generation of sex bias among helminth-infected hosts. However, sex hormones not only can modulate the course of infection but also can be exploited by the parasites, and helminths appear to have developed molecules and pathways for this purpose. Furthermore, host sex may influence the efficacy of anti-helminth vaccines; however, although little data exist regarding this sex-dependent efficacy, host sex is known to influence the response to vaccines. Despite its importance, host sex is frequently overlooked in parasitological studies. This review focuses on the key contributors to sex bias in the case of helminth infection. The precise nature of the mechanisms/factors determining these sex-specific differences generally remains largely unknown, and this represents an obstacle in the development of control methods. There is an urgent need to identify any protective elements that could be targeted in future therapies to provide optimal disease management with regard to host sex. Hence, more research is needed into the impact of host sex on immunity and protection.

Conditional knockout of oestrogen receptor alpha in CD11c+ cells impacts female survival and inflammatory cytokine profile in murine lupus

Oestrogen and oestrogen receptor alpha (ERα) have been implicated in systemic lupus erythematosus pathogenesis. ERα signalling influences dendritic cell (DC) development and function, as well as inflammation and downstream immune responses. We previously reported that ERα modulates multiple Toll-like receptor-stimulated pathways in both conventional and plasmacytoid DCs in lupus-prone mice. For example, CD11chi MHCII+ cell numbers are reduced in mice with global ERα deficiency or when expressing a short variant of ERα. Herein, RNA-seq analysis of CD11chi cells from bone marrow of NZM2410 mice expressing WT ERα versus ERα short versus ERα null revealed differentially expressed complement genes, interferon-related genes and cytokine signalling (e.g., IL-17 and Th17 pathways). To better understand the role of ERα in CD11c+ cells, lupus prone NZM2410 mice with selective deletion of the Esr1 gene in CD11c+ cells were generated. Phenotype and survival of these mice were similar with the exception of Cre positive (CrePos) female mice. CrePos females, but not males, all died unexpectedly prior to 35 weeks. DC subsets were not significantly different between groups. Since ERα is necessary for robust development of DCs, this result suggests that DC fate was determined prior to CD11c expression and subsequent ERα deletion (i.e., proximally in DC ontogeny). Overall, findings point to a clear functional role for ERα in regulating cytokine signalling and inflammation, suggesting that further study into ERα-mediated regulatory mechanisms in DCs and other immune cell types is warranted.

Sex and gender differences in community-acquired pneumonia

Awareness of the influence of sex ands gender on the natural history of several diseases is increasing. Community-acquired pneumonia (CAP) is the most common acute respiratory disease, and it is associated with both morbidity and mortality across all age groups. Although a role for sex- and gender-based differences in the development and associated complications of CAP has been postulated, there is currently high uncertainty on the actual contribution of these factors in the epidemiology and clinical course of CAP. More evidence has been produced on the topic during the last decades, and sex- and gender-based differences have also been extensively studied in COVID-19 patients since the beginning of the SARS-CoV-2 pandemic. This review aims to provide an extensive outlook of the role of sex and gender in the epidemiology, pathogenesis, treatment, and outcomes of patients with CAP, and on the future research scenarios, with also a specific focus on COVID-19.

Impact of Dialysis Clinical Operating Conditions on Human Serum Protein-Mediated Inflammatory Biomarkers Released in Patients Using Polyarylethersulfone Membranes

Hemodialysis (HD) is a life-sustaining treatment of crucial importance in managing end-stage renal disease (ESRD). However, this membrane-based therapy is associated with acute side-effects due to bioincompatibility issues and limitations on the removal of uremic toxins. The present study assessed the influence of hydrodynamic conditions applied during HD treatment on protein-mediated inflammatory and thrombotic responses. The membrane modules considered are commonly used in Canadian hospitals and are comprised of a polymer blend of polyarylether sulfone-polyvinylpyrrolidone (PAES). The membranes morphology and hydrophilicity were assessed using SEM, AFM, BET, and zeta potential. An in vitro study evaluated the adsorptive behavior of fibrinogen (FB) to the membrane under different flow conditions. Lower rates of 200 mL/min promoted slower and significant FB adsorption, leading to more severe inflammatory and thrombotic responses. Hydrodynamic conditions also affected the concentration of all inflammatory biomarkers. Lower flow rates triggered more complement activation as well as coagulation, clotting, and inflammatory responses compared to higher flow rates. At the end of the dialysis session, patients treated with a Qb of 200 mL/min presented a significant increase in the concentration of C5a (232%), properdin (114%), serpin (545%), IL-1α (50%), IL-6 (450%), and vWF (212%). IL-1β and TNF-α concentrations declined by 12.5 and 35.5%, respectively. Male patients experienced more severe inflammatory responses than female patients at the operating conditions considered. Comparing the pre- and post-dialysis levels of female and male patients, female patients experienced significantly higher levels of IL-6 and properdin, while male patients presented higher levels of C5a, IL-1α, and IL-6. The results of this study will help clinical doctors evaluate the impact of HD operating conditions on blood activations before prescribing treatment and inform expectations for outcomes in female and male patients.

Expression of glucocorticoid and androgen receptors in bone marrow-derived hematopoietic and nonhematopoietic murine endometrial cells

OBJECTIVE

To determine whether bone marrow (BM)-derived cells engrafting the murine endometrium express the glucocorticoid receptor (GR) and androgen receptor (AR). Recent data demonstrate that BM is a long-term source of multiple hematopoietic and nonhematopoietic endometrial cell types. Important roles for glucocorticoids and androgens in regulating endometrial functions, including decidualization and early embryo attachment/invasion, have very recently emerged. Whether endometrial cells of BM origin express glucocorticoid or ARs has not been previously studied.

DESIGN

Animal study.

SETTING

Basic science laboratory.

ANIMAL(S)

Wild-type C57BL/6J male mice expressing enhanced green fluorescent protein (GFP) and syngeneic wild-type C57BL/6J female mice aged 6-9 weeks.

INTERVENTION(S)

Murine bone marrow transplant.

MAIN OUTCOME MEASURE(S)

Bone marrow cells were harvested from adult wild-type C57BL/6 mice and subjected to flow cytometry to identify the percentage of hematopoietic and nonhematopoietic cells expressing GR or AR. Uterine tissue sections from lethally irradiated syngeneic adult female C57BL/6 mice that had been recipients of BM transplants from adult male transgenic donor mice ubiquitously expressing GFP were studied. Immunohistochemistry was performed in the uterine tissue sections of the recipient mice at 5, 9, and 12 months after transplant using specific anti-GR, anti-AR, anti-GFP, anti-CD45 (pan leukocyte marker), and anti-F4/80 (murine macrophage marker) primary antibodies. Confocal laser microscopy was used to localize and quantitate BM-derived (GFP⁺) cell types in the endometrial stromal and epithelial compartments and determine whether BM-derived cell types in the murine endometrium express GR or AR.

RESULT(S)

Hematopoietic cells comprised 93.6%-96.6% of all cells in the BM, of which 98.1% ± 0.2% expressed GR and 92.2% ± 4.4% expressed AR. Nonhematopoietic cells comprised 0.4%-1.3% of BM, of which 52.8% ± 5.9% expressed GR and 48.9% ± 3.4% expressed AR. After BM transplant, the proportion of cells originating from BM in the endometrial stromal compartment increased over time, reaching 13.5% ± 2.3% at 12 months after transplant. In the epithelial compartments, <1% of the cells were of BM origin at 12 months after transplant. Most (60%-72%) GR⁺ and/or AR⁺ BM-derived cells in the stroma were hematopoietic (CD45⁺) cells, of which 37%-51% were macrophages. Nonetheless, 28%-33% of GR⁺ cells, and 28%-40% of AR⁺ BM-derived cells, were nonhematopoietic (CD45^-) stromal cells of BM origin.

CONCLUSION(S)

A substantial number of BM-derived cells express GR and AR, suggesting a role for these cells in both glucocorticoid-regulated and androgen-regulated endometrial functions, such as proliferation and/or decidualization.

Gender-Diverse Inclusion in Immunological Research: Benefits to Science and Health

The differences between male and female immune systems are an under-researched field, ripe for discovery. This is evidenced by the stark sex biases seen in autoimmunity and infectious disease. Both the sex hormones (oestrogen and testosterone), as well as the sex chromosomes have been demonstrated to impact immune responses, in multiple ways. Historical shortcomings in reporting basic and clinical scientific findings in a sex-disaggregated manner have led not only to limited discovery of disease aetiology, but to potential inaccuracies in the estimation of the effects of diseases or interventions on females and gender-diverse groups. Here we propose not only that research subjects should include both cis-gender men and cis-gender women, but also transgender and gender-diverse people alongside them. The known interaction between the hormonal milieu and the sex chromosomes is inseparable in cis-gender human research, without the confounders of puberty and age. By inclusion of those pursuing hormonal affirmation of their gender identity- the individual and interactive investigation of hormones and chromosomes is permitted. Not only does this allow for a fine-tuned dissection of these individual effects, but it allows for discovery that is both pertinent and relevant to a far wider portion of the population. There is an unmet need for detailed treatment follow-up of the transgender community- little is known of the potential benefits and risks of hormonal supplementation on the immune system, nor indeed on many other health and disease outcomes. Our research team has pioneered the inclusion of gender-diverse persons in our basic research in adolescent autoimmune rheumatic diseases. We review here the many avenues that remain unexplored, and suggest ways in which other groups and teams can broaden their horizons and invest in a future for medicine that is both fruitful and inclusive.

Sex-biased adaptive immune regulation in cancer development and therapy

The cancer research field is finally starting to unravel the mystery behind why males have a higher incidence and mortality rate than females for nearly all cancer types of the non-reproductive systems. Here, we explain how sex - specifically sex chromosomes and sex hormones - drives differential adaptive immunity across immune-related disease states including cancer, and why males are consequently more predisposed to tumor development. We highlight emerging data on the roles of cell-intrinsic androgen receptors in driving CD8⁺ T cell dysfunction or exhaustion in the tumor microenvironment and summarize ongoing clinical efforts to determine the impact of androgen blockade on cancer immunotherapy. Finally, we outline a framework for future research in cancer biology and immuno-oncology, underscoring the importance of a holistic research approach to understanding the mechanisms of sex dimorphisms in cancer, so sex will be considered as an imperative factor for guiding treatment decisions in the future.

Progesterone and Inflammatory Response in the Oviduct during Physiological and Pathological Conditions

Progesterone has been shown to be a potent suppressor of several inflammatory pathways. During pregnancy, progesterone levels increase, allowing for normal pregnancy establishment and maintenance. The dysregulation of progesterone, as well as inflammation, leads to poor pregnancy outcomes. However, it is unclear how progesterone imbalance could impact inflammatory responses in the oviduct and subsequently result in early pregnancy loss. Therefore, in this review, we describe the role of progesterone signaling in regulating the inflammatory response, with a focus on the oviduct and pathological conditions in the Fallopian tubes.

Sex-Specific Environmental Impacts on Initiation and Progression of Multiple Sclerosis

The immunological mechanisms that contribute to multiple sclerosis (MS) differ between males and females. Females are 2–3 times more likely to develop MS compared to males, however the reason for this discrepancy is unknown. Once MS is established, there is a more inflammatory yet milder form of disease in females whereas males generally suffer from more severe disease and faster progression, neural degradation, and disability. Some of these differences relate to genetics, including genetic control of immune regulatory genes on the X-chromosome, as well as immune modulatory properties of sex hormones. Differences in MS development may also relate to how sex interacts with environmental risk factors. There are several environmental risk factors for MS including late-onset Epstein Barr virus infection, low serum vitamin D levels, low UV radiation exposure, smoking, obesity, and lack of physical activity. Most of these risk factors impact males and females differently, either due to biological or immunological processes or through behavioral differences. In this review, we explore these differences further and focus on how the interaction of environmental risk factors with sex hormones may contribute to significantly different prevalence and pathology of MS in males and females.

Progesterone: A Unique Hormone with Immunomodulatory Roles in Pregnancy

Progesterone is well known for its numerous endocrinologic roles in pregnancy but is also endowed with fascinating immunomodulatory capabilities. It can downregulate the induction of inflammatory reactions, the activation of immune cells and the production of cytokines, which are critical mediators of immune responses. These features appear to be critical to the success of pregnancy, given the ability of maternal immune reactivity to interfere with pregnancy and to contribute to several pregnancy complications. This review summarizes the contribution of maternal immune effectors in general, and cytokines in particular, to pregnancy complications such as recurrent miscarriage, pre-eclampsia and preterm labor; it describes the promise offered by supplementation with progesterone and the oral progestogen dydrogesterone, as well as the progesterone-induced blocking factor in the prevention and/or treatment of these serious complications.

Interferon Signaling in Estrogen Receptor-positive Breast Cancer: A Revitalized Topic

Cancer immunology is the most rapidly expanding field in cancer research, with the importance of immunity in cancer pathogenesis now well accepted including in the endocrine-related cancers. The immune system plays an essential role in the development of ductal and luminal epithelial differentiation in the mammary gland. Originally identified as evolutionarily conserved antipathogen cytokines, interferons (IFNs) have shown important immune-modulatory and antineoplastic properties when administered to patients with various types of cancer, including breast cancer. Recent studies have drawn attention to the role of tumor- and stromal-infiltrating lymphocytes in dictating therapy response and outcome of breast cancer patients, which, however, is highly dependent on the breast cancer subtype. The emerging role of tumor cell-inherent IFN signaling in the subtype-defined tumor microenvironment could influence therapy response with protumor activities in breast cancer. Here we review evidence with new insights into tumor cell-intrinsic and tumor microenvironment-derived IFN signaling, and the crosstalk of IFN signaling with key signaling pathways in estrogen receptor-positive (ER+) breast cancer. We also discuss clinical implications and opportunities exploiting IFN signaling to treat advanced ER+ breast cancer.

Evaluation of the sex steroids mediated modulation of leucocyte immune responses in an ophidian Natrix piscator

The immune-suppressive role of sex steroids in mammals is well documented, but information on other vertebrates is limited. The present study was planned to analyze the effect of testosterone and progesterone in the modulation of immune functions of leucocytes in a reptile, Natrix piscator. Reptiles are unique organisms and this study is novel in that it provides an insight into immune-reproductive cross-talk in a reptile. Leucocytes were isolated from peripheral blood, cultured with different concentrations of testosterone and progesterone and different immune parameters like phagocytosis, superoxide production, and nitrite release were assessed. Lymphocytes were isolated and cell-mediated immunity was assessed through proliferation responses utilizing tetrazolium salt. Concentration-dependent suppressive effects of both the steroids on immune responses were observed. A differential suppressive effect of testosterone was also observed when a lymphocyte proliferation assay was studied. Using receptor antagonists such as cyproterone acetate and mifepristone restored the immune responses of cultured cells. It was summarized that gonadal steroids mediate a direct suppressive effect on innate and cell-mediated immune responses of blood immune cells. It was concluded that when gonadal steroids are high in reproductive seasons, the immune functions are suppressed to gain optimum reproductive success.

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Reptilian immune responses are differentially affected by sex steroids.

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Testosterone interacts with nuclear receptors and suppress proliferative responses of lymphocytes.

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Superoxide anion production by blood immune cells are inhibited by gonadal steroids.

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Use of receptor antagonists resulted in amelioration of immune responses indicating the direct action of steroids.

Identification of Profound Metabolic Alterations in Human Dendritic Cells by Progesterone Through Integrated Bioinformatics Analysis

Maintaining the homeostasis of the decidual immune microenvironment at the maternal-fetal interface is essential for reproductive success. Dendritic cells (DCs) are the professional antigen-presenting cells and dominate this balance of immunogenicity and tolerance. Progesterone (P4) is highlighted as the “hormone of pregnancy” in most eutherian mammals because of its regulatory role in immune-endocrine behavior during pregnancy. Recent studies have shown that P4 is associated with the differentiation and function of DCs, however, the underlying mechanisms remain unidentified. In addition, while progress in the field of immunometabolism has highlighted the intimate connections between the metabolism phenotype and the immunogenic or tolerogenic fate of DCs, whether P4 can affect DCs metabolism and thus exert a functional manipulation has not yet been explored. In this study, we acquired human peripheral blood monocyte-derived DCs and conducted RNA sequencing (RNA-seq) on immature DCs (iDCs), P4-treated DCs (pDCs), and mature DCs (mDCs), aiming to comprehensively assess the effects of P4 on DCs. Our results showed pDCs performed a distinct differentially expressed genes (DEGs) profile compared with iDCs or mDCs. Further functional enrichment and weighted gene co-expression network (WGCNA) analysis found that these DEGs were related not only to the cellular components but also to the significant metabolic activities, including mitochondrial oxidative phosphorylation (OXPHOS) and fatty acid metabolism. In addition, these changes may be involved in the activation of various signaling pathways of PI3K/Akt/mTOR, AMPK/PGC1-α, and PPAR-γ. In summary, our work suggested that P4 induced profound metabolic alterations of mitochondrial OXPHOS and fatty acid metabolism in DCs. Our findings may provide new insights into the role of P4 in DCs.

Suppression of Dendritic Cell Maturation by Kefir Peptides Alleviates Collagen-Induced Arthritis in Mice

Arthritis is a disorder that is characterized by joint inflammation and other symptoms. Rheumatoid arthritis (RA), an autoimmune disease, is one of the most common arthritis in worldwide. Inflammation of the synovium is the main factor that triggers bone erosion in the joints in RA, but the pathogenesis of RA is not clearly understood. Kefir grain-fermented products have been demonstrated to enhance immune function and exhibit immune-modulating bioactivities. This study aims to explore the role of kefir peptides (KPs) on the regulation of dendritic cell, which are found in RA synovial fluid, and the protection effects of KPs on mice with collagen-induced arthritis (CIA). Immature mouse bone marrow-derived dendritic cells (BMDCs) were treated with KPs (2.2 and 4.4 mg/ml) and then exposed to lipopolysaccharide (LPS) to study the immune regulation function of KPs in dendritic cells. Mice with CIA (n = 5 per group) were orally administrated KPs (3.75 and 7.5 mg/day/kg) for 21 days and therapeutic effect of KPs on mice with arthritis were assessed. In this study, we found that KPs could inhibit surface molecule expression, reduce inflammatory cytokine release, and repress NF-κB and MAPK signaling in LPS-stimulated mouse BMDCs. In addition, a high dose of KPs (7.5 mg/kg) significantly alleviated arthritis symptoms, decreased inflammatory cytokine expression, suppressed splenic DC maturation and decrease the percentage of Th1 and Th17 in the spleens on mice with CIA. Our findings demonstrated that KPs ameliorate CIA in mice through the mechanism of suppressing DC maturation and inflammatory cytokine releases.

A genotype-phenotype screening system using conditionally immortalized immature dendritic cells

Here, we describe a protocol for CRISPR/Cas9-mediated gene knockout in conditionally immortalized immature dendritic cells (DCs), which can be limitlessly expanded before differentiation. This facilitates the genetic screening of DC functions in vitro including assessment of phagocytosis, cytokine production, expression of co-stimulatory or co-inhibitory molecules, and antigen presentation, as well as evaluation of the capacity to elicit anticancer immune responses in vivo. Altogether, these approaches described in this protocol allow investigators to link the genotype of DCs to their phenotype.

For complete details on the use and execution of this protocol, please refer to Le Naour et al. (2020).

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Conditionally immortalized immature dendritic cells (DCs) can be expanded without limits

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A CRISPR/Cas9 system allows for genetic screening of DC functions

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Different DC functions are assessed in vitro

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DC genotype-dependent anticancer immunity can be determined in mice

Administration of Exogenous Progesterone Protects Against Brucella abortus Infection-Induced Inflammation in Pregnant Mice

Progesterone has been recognized as essential for the establishment and maintenance of pregnancy, and is typically known as an immunosuppressive agent. However, its effects on mediating Brucella infection-induced inflammation have not been evaluated. Here we demonstrated that Brucella abortus infection inhibits progesterone levels in the pregnant mouse by suppressing the production of progesterone by placenta. Progesterone treatment significantly reduced the secretion of inflammatory cytokines in serum, macrophages, and trophoblasts of B. abortus-infected mice, leading to decreased placentitis and enhancing the pup viability. Mechanistically, this decreased inflammatory response results from inhibition of NF-kB activation by progesterone. Moreover, progesterone treatment suppresses B. abortus growth within trophoblasts associated with an inability of bacteria to escape the late endosome compartment in vitro. Collectively, our data illustrate that progesterone treatment might be useful therapeutically in protection against placentitis or abortion caused by B. abortus infection.

Viral infection of the ovaries compromises pregnancy and reveals innate immune mechanisms protecting fertility

Viral infections during pregnancy are a considerable cause of adverse outcomes and birth defects, and the underlying mechanisms are poorly understood. Among those, cytomegalovirus (CMV) infection stands out as the most common intrauterine infection in humans, putatively causing early pregnancy loss. We employed murine CMV as a model to study the consequences of viral infection on pregnancy outcome and fertility maintenance. Even though pregnant mice successfully controlled CMV infection, we observed highly selective, strong infection of corpus luteum (CL) cells in their ovaries. High infection densities indicated complete failure of immune control in CL cells, resulting in progesterone insufficiency and pregnancy loss. An abundance of gap junctions, absence of vasculature, strong type I interferon (IFN) responses, and interaction of innate immune cells fully protected the ovarian follicles from viral infection. Our work provides fundamental insights into the effect of CMV infection on pregnancy loss and mechanisms protecting fertility.

Effects of Hormone Therapy and Flavonoids Capable on Reversal of Menopausal Immune Senescence

Menopause, probably the most important natural change in a woman’s life and a major component of female senescence, is characterized, inter alia, by cessation of ovarian estrogen and progesterone production, resulting in a gradual deterioration of the female immune system. Hormone replacement therapy (HRT) is used in postmenopausal women to relieve some of the peri- and postmenopausal symptoms, while there is also evidence that the therapy may additionally partially reverse menopausal immune senescence. Flavonoids, and especially isoflavones, are widely used for the treatment of menopausal symptoms, although it is not at present clear whether they can reverse or alleviate other menopausal changes. HRT reverses the menopausal CD4/CD8 ratio and also limits the general peri- and postmenopausal inflammatory state. Moreover, the increased levels of interleukins (IL)-1β, IL-6, and IL-8, as well as of tumor necrosis factor-α (TNF-α) are decreased after the initiation of HRT. However, some reports show no effect of HRT on IL-4, IL-10, and IL-12. It is thus evident that the molecular pathways connecting HRT and female immune senescence need to be clarified. Interestingly, recent studies have suggested that the anti-inflammatory properties of isoflavones possibly interact with inflammatory cytokines when applied in menopause treatments, thereby potentially reversing immune senescence. This narrative review presents the latest data on the effect of menopausal therapies, including administration of flavonoid-rich products, on age-associated immune senescence reversal with the aim of revealing possible directions for future research and treatment development.

The human memory T cell compartment changes across tissues of the female reproductive tract

Memory CD4 T cells in tissues fulfill numerous functions that are critical for local immune homeostasis and protection against pathogens. Previous studies have highlighted the phenotypic and functional heterogeneity of circulating and tissue-resident memory CD4 T cells across different human tissues such as skin, lung, liver, and colon. Comparatively little is known in regard to memory CD4 T cells across tissues of the female reproductive tract (FRT). We examined CD4 T cells in donor-matched vaginal, ecto- and endocervical tissues, which differ in mucosal structure and exposure to external environmental stimuli. We hypothesized that this could be reflected by tissue-specific differences in the memory CD4 T cell compartment. We found differences in CD4 subset distribution across these tissues. Specifically, CD69⁺CD103⁺ CD4 T cells were significantly more abundant in vaginal than cervical tissues. In contrast, the transcriptional profiles of CD4 subsets were fairly conserved across FRT tissues. CD69⁺CD103⁺ CD4 T cells showed a T_H17 bias independent of tissue niche. Our data suggest that FRT tissues affect T cell subset distribution but have limited effects on the transcriptome of each subset. We discuss the implications for barrier immunity in the FRT.

Association between oral contraceptives and serious infections: A population-based cohort study

AIMS

Oral contraceptives (OC)s are commonly used worldwide. In a recent study, we showed that the use of OCs is associated with an increased risk for neutropenia. We aimed to investigate the clinical implications of this finding by examining the infection rates of 4 serious infections before, during and after OCs.

METHODS

A retrospective cohort study using the electronic medical records of a large health organization. We selected 2 retrospective cohorts of women aged 16-40 between years 2005 and 2019. The first cohort examined infection rates during 2 years before OC use and 2 consecutive years of adherent OC use. The second cohort included women who consumed OCs adherently for 2 years and then discontinued their use for 2 consecutive years. Women's infection rates were compared by χ² test, results were stratified by OC type and age.

RESULTS

Overall, 21 595 and 20 728 women were included in Cohorts 1 and 2 respectively. We found a statistically significant higher relative risk for infection while using OCs; the overall risk ratios (95% confidence intervals) for infection in Cohorts 1 and 2 were 1.35 (1.32-1.38) and 1.27 (1.24-1.31), respectively. The overall infection risk remained statistically significant when stratified by age.

CONCLUSIONS

This study demonstrates a high statistically and clinically significant risk for all infections followed during OC consumption, which is likely to have major clinical and economic implications. These findings may have implications to millions of women worldwide and should lead to more research on the safety of the pill.

Progesterone Suppresses Neisseria gonorrhoeae-Induced Inflammation Through Inhibition of NLRP3 Inflammasome Pathway in THP-1 Cells and Murine Models

Asymptomatic/subclinical gonococcal infections in females continue to be prevalent within the general population, thus emerging as a global health problem. However, the reasons for these clinical manifestations are unknown. Our group had previously found out that in females, asymptomatic gonococcal infections correlate with higher serum progesterone (P4) levels and lower IL-1β levels in cervical secretions. We used murine infection model and THP-1 cells to determine whether P4 exerts anti-inflammatory effects on gonococcal infections. In the murine infection model, P4 (1 mg/day) inhibited the inflammatory effects induced by gonococcal infections which led to decreased neutrophil infiltration, reduced polymorphonuclear neutrophils (PMNs) numbers, IL-1β, TNF-α, and IL-6 levels in vaginal secretions. In addition, P4 down-regulated the mRNA and protein levels of NLRP3, associated with lower mRNA levels of pro-IL-1β, repressed caspase-1 activity in genital tissues and THP-1 cells. Moreover, P4 suppressed the phosphorylation levels of NF-κB and attenuated Neisseria gonorrhoeae (N. gonorrhoeae, gonococci or GC)-induced ROS generation. This is consistent with the two signals required for activation of the NLRP3 (NOD-, LRR-, and pyrin domain-containing protein 3) inflammasome. In conclusion, our result shows that P4 suppresses the gonococci induced-inflammation, especially through the NLRP3 inflammasome pathway, and partially explains the pathogenesis of asymptomatic GC infection in women.

Sexual Dimorphism in Innate Immunity: The Role of Sex Hormones and Epigenetics

Sexual dimorphism refers to differences between biological sexes that extend beyond sexual characteristics. In humans, sexual dimorphism in the immune response has been well demonstrated, with females exhibiting lower infection rates than males for a variety of bacterial, viral, and parasitic pathogens. There is also a substantially increased incidence of autoimmune disease in females compared to males. Together, these trends indicate that females have a heightened immune reactogenicity to both self and non-self-molecular patterns. However, the molecular mechanisms driving the sexually dimorphic immune response are not fully understood. The female sex hormones estrogen and progesterone, as well as the male androgens, such as testosterone, elicit direct effects on the function and inflammatory capacity of immune cells. Several studies have identified a sex-specific transcriptome and methylome, independent of the well-described phenomenon of X-chromosome inactivation, suggesting that sexual dimorphism also occurs at the epigenetic level. Moreover, distinct alterations to the transcriptome and epigenetic landscape occur in synchrony with periods of hormonal change, such as puberty, pregnancy, menopause, and exogenous hormone therapy. These changes are also mirrored by changes in immune cell function. This review will outline the evidence for sex hormones and pregnancy-associated hormones as drivers of epigenetic change, and how this may contribute to the sexual dimorphism. Determining the effects of sex hormones on innate immune function is important for understanding sexually dimorphic autoimmune diseases, sex-specific responses to pathogens and vaccines, and how innate immunity is altered during periods of hormonal change (endogenous or exogenous).

Stress, Sex, and Sugar: Glucocorticoids and Sex-Steroid Crosstalk in the Sex-Specific Misprogramming of Metabolism

Early-life exposures to environmental insults can misprogram development and increase metabolic disease risk in a sex-dependent manner by mechanisms that remain poorly characterized. Modifiable factors of increasing public health relevance, such as diet, psychological stress, and endocrine-disrupting chemicals, can affect glucocorticoid receptor signaling during gestation and lead to sex-specific postnatal metabolic derangements. Evidence from humans and animal studies indicate that glucocorticoids crosstalk with sex steroids by several mechanisms in multiple tissues and can affect sex-steroid-dependent developmental processes. Nonetheless, glucocorticoid sex-steroid crosstalk has not been considered in the glucocorticoid-induced misprogramming of metabolism. Herein we review what is known about the mechanisms by which glucocorticoids crosstalk with estrogen, androgen, and progestogen action. We propose that glucocorticoid sex-steroid crosstalk is an understudied mechanism of action that requires consideration when examining the developmental misprogramming of metabolism, especially when assessing sex-specific outcomes.

Mutations in the Progesterone Receptor (PROGINS) May Reduce the Symptoms of Acute Hepatitis E and Protect Against Infection

BACKGROUND

Mutations in the progesterone receptor (PR) gene, PROGINS, have been studied in relation to hepatitis E virus (HEV) infection. Patients with the PROGINS gene may develop a worse clinical course of hepatitis E. The aim of our study was to evaluate the influence of PROGINS on the susceptibility to and the clinical course of HEV infection in HIV patients.

METHODS

This study included patients with HIV who were evaluated in previous prospective studies for the prevalence and incidence of HEV. The following three groups of patients were studied: (i) never infected, (ii) past infections, and (iii) recently infected. We determined the PR genotype to evaluate the proportion of patients who were homozygous for PROGINS according to HEV infection. We also compared the proportion of PROGINS carriers with a recent HEV infection according to their symptomatology.

RESULTS

In this study, 311 patients infected with HIV were included. Of those patients, 198 were homozygous wild type (63.7%), 91 were heterozygous (29.3%), and 22 were homozygous PROGINS (7.1%). We found that the homozygous PROGINS genotype in women was associated with a lower HEV seroprevalence. In addition, in patients with a recent HEV infection, none of those homozygous for PROGINS presented symptoms.

CONCLUSION

The PROGINS mutation plays a protective role against HEV infection and is associated with subclinical infection in HIV-infected patients, particularly women.

Pregnancy Immunogenetics and Genomics: Implications for Pregnancy-Related Complications and Autoimmune Disease

Pregnancy presents a singular physiological scenario during which the maternal immune system must accommodate the semiallogeneic fetus. Fluctuations between pro- and anti-inflammatory states are required throughout gestation to facilitate uterine tissue remodeling, fetal growth and development, and finally birth. Tolerance for the fetus must be established and maintained without fundamentally compromising the maternal immune system function, so that both the mother and fetus are protected from foreign insults. Here, we review our current understanding of how genetic variation at both maternal and fetal loci affects implantation and placenta formation, thereby determining the likelihood of a successful pregnancy outcome or the development of pregnancy-related complications. We also consider the impact of pregnancy on both the maternal and fetal systemic immune systems and the related implications for modulating ongoing autoimmune diseases and triggering their development.

Sex bias in autoimmunity

PURPOSE OF REVIEW

To give an overview of recently published articles addressing the mechanisms underlying sex bias in autoimmune disease.

RECENT FINDINGS

Recent studies investigating the origins of sex bias in autoimmune disease have revealed an extensive and interconnected network of genetic, hormonal, microbial, and environmental influences. Investigation of sex hormones has moved beyond profiling the effects of hormones on activity and prevalence of immune cell types to defining the specific immunity-related genes driving these changes. Deeper examination of the genetic content of the X and Y chromosomes and genetic escapees of X chromosome inactivation has revealed some key drivers of female-biased autoimmunity. Animal studies are offering further insights into the connections among microbiota, particularly that of the gut, and the immune system.

SUMMARY

Sex bias in autoimmune disease is the manifestation of a complex interplay of the sex chromosomes, sex hormones, the microbiota, and additional environmental and sociological factors.

The Wonder Years: What Can Primary School Children Teach Us About Immunity to Mycobacterium tuberculosis?

In high burden settings, the risk of infection with Mycobacterium tuberculosis increases throughout childhood due to cumulative exposure. However, the risk of progressing from tuberculosis (TB) infection to disease varies by age. Young children (<5 years) have high risk of disease progression following infection. The risk falls in primary school children (5 to <10 years), but rises again during puberty. TB disease phenotype also varies by age: generally, young children have intrathoracic lymph node disease or disseminated disease, while adolescents (10 to <20 years) have adult-type pulmonary disease. TB risk also exhibits a gender difference: compared to adolescent boys, adolescent girls have an earlier rise in disease progression risk and higher TB incidence until early adulthood. Understanding why primary school children, during what we term the "Wonder Years," have low TB risk has implications for vaccine development, therapeutic interventions, and diagnostics. To understand why this group is at low risk, we need a better comprehension of why younger children and adolescents have higher risks, and why risk varies by gender. Immunological response to M. tuberculosis is central to these issues. Host response at key stages in the immunopathological interaction with M. tuberculosis influences risk and disease phenotype. Cell numbers and function change dramatically with age and sexual maturation. Young children have poorly functioning innate cells and a Th2 skew. During the "Wonder Years," there is a lymphocyte predominance and a Th1 skew. During puberty, neutrophils become more central to host response, and CD4+ T cells increase in number. Sex hormones (dehydroepiandrosterone, adiponectin, leptin, oestradiol, progesterone, and testosterone) profoundly affect immunity. Compared to girls, boys have a stronger Th1 profile and increased numbers of CD8+ T cells and NK cells. Girls are more Th2-skewed and elicit more enhanced inflammatory responses. Non-immunological factors (including exposure intensity, behavior, and co-infections) may impact disease. However, given the consistent patterns seen across time and geography, these factors likely are less central. Strategies to protect children and adolescents from TB may need to differ by age and sex. Further work is required to better understand the contribution of age and sex to M. tuberculosis immunity.

Sex Hormones Regulate Innate Immune Cells and Promote Sex Differences in Respiratory Virus Infection

Sex differences in the incidence and severity of respiratory virus infection are widely documented in humans and murine models and correlate with sex biases in numbers and/or functional responses of innate immune cells in homeostasis and lung infection. Similarly, changes in sex hormone levels upon puberty, pregnancy, and menopause/aging are associated with qualitative and quantitative differences in innate immunity. Immune cells express receptors for estrogens (ERα and ERβ), androgens (AR), and progesterone (PR), and experimental manipulation of sex hormone levels or receptors has revealed that sex hormone receptor activity often underlies sex differences in immune cell numbers and/or functional responses in the respiratory tract. While elegant studies have defined mechanistic roles for sex hormones and receptors in innate immune cells, much remains to be learned about the cellular and molecular mechanisms of action of ER, PR, and AR in myeloid cells and innate lymphocytes to promote the initiation and resolution of antiviral immunity in the lung. Here, we review the literature on sex differences and sex hormone regulation in innate immune cells in the lung in homeostasis and upon respiratory virus infection.

Deciphering sex differences in the immune system and depression

Certain mood disorders and autoimmune diseases are predominately female diseases but we do not know why. Here, we explore the relationship between depression and the immune system from a sex-based perspective. This review characterizes sex differences in the immune system in health and disease. We explore the contribution of gonadal and stress hormones to immune function at the cellular and molecular level in the brain and body. We propose hormonal and genetic sex specific immune mechanisms that may contribute to the etiology of mood disorders.

The Impact of Sex on Alloimmunity

Transplantation outcomes are known to be affected by multiple factors, including donor and recipient sex. Aside from the physiological characteristics of male and female donor allografts, accumulating evidence suggests that additional features underlie sex-specific immune responses that affect graft survival. We discuss here aspects of innate and adaptive alloimmunity that are specific to males and females in the context of underlying genetic and hormonal factors. These differences likely contribute to the observed disparities in graft survival. Understanding these features in more detail may lead to improved strategies for optimizing the results of organ transplantation.

Progesterone-based compounds affect immune responses and susceptibility to infections at diverse mucosal sites

Over 100 million women worldwide are currently on progesterone-based contraceptives to improve their health outcomes through reduced maternal mortality and family planning. In addition to their role in reproduction, progesterone-based compounds modulate immune responses throughout the body, particularly at mucosal sites. By binding to receptors located in immune cells, including natural killer cells, macrophages, dendritic cells, and T cells, as well in non-immune cells, such as epithelial and endothelial cells, progesterone-based compounds alter cellular signaling and activity to affect the outcome of infections at diverse mucosal sites, including the genital, gastrointestinal, and respiratory tracts. As the use of progesterone-based compounds, in the form of contraceptives and hormone-based therapies, continue to increase worldwide, greater consideration should be given to how the immunomodulatory effects these compounds alter the outcome of diseases at mucosal sites beyond the reproductive tract, which has profound implications for women's health.

Sex-specific regulation of immune responses by PPARs

The prevalence of autoimmune, infectious and metabolic diseases is different for men and women owing to the respective ability of their immune systems to respond to self and foreign antigens. Although several factors, including hormones and the X-chromosome, have been suggested to contribute to such sex-specific immune responses, the underlying factors remain poorly defined. Recent studies using peroxisome proliferator-activated receptor (PPAR) ligands and knockout mice have identified sex-dimorphic expression of PPARs, and have shown that the inhibitory functions of PPAR in T cells are substantially affected by the sex hormones. In this review, we consider the sex-specific differences in PPARs and summarize the diverse PPAR-mediated, sex-specific properties of effector T-cell responses, such as T-cell activation, survival and differentiation, as well as their involvement in T-cell-related autoimmune diseases, including colitis, graft-versus-host disease and experimental autoimmune encephalomyelitis. Understanding PPAR-mediated sex differences in immune responses will provide more precise insights into the roles of PPARs in effector T cells.

Progesterone-Based Contraceptives Reduce Adaptive Immune Responses and Protection against Sequential Influenza A Virus Infections

In addition to their intended use, progesterone (P4)-based contraceptives promote anti-inflammatory immune responses, yet their effects on the outcome of infectious diseases, including influenza A virus (IAV) infection, are rarely evaluated. To evaluate their impact on immune responses to sequential IAV infections, adult female mice were treated with placebo or one of two progestins, P4 or levonorgestrel (LNG), and infected with a mouse-adapted H1N1 (maH1N1) virus. Treatment with P4 or LNG reduced morbidity but had no effect on pulmonary virus titers during primary H1N1 infection compared to placebo treatment. In serum and bronchoalveolar lavage fluid, total anti-IAV IgG and IgA titers and virus-neutralizing antibody titers but not hemagglutinin stalk antibody titers were lower in progestin-treated mice than placebo-treated mice. Females were challenged 6 weeks later with either an maH1N1 drift variant (maH1N1dv) or maH3N2 IAV. The level of protection following infection with the maH1N1dv was similar among all groups. In contrast, following challenge with maH3N2, progestin treatment reduced survival as well as the numbers and activity of H1N1- and H3N2-specific memory CD8⁺ T cells, including tissue-resident cells, compared with placebo treatment. In contrast to primary IAV infection, progestin treatment increased the titers of neutralizing and IgG antibodies against both challenge viruses compared with those achieved with placebo treatment. While the immunomodulatory properties of progestins protected immunologically naive female mice from the severe outcomes from IAV infection, it made them more susceptible to secondary challenge with a heterologous IAV, despite improving their antibody responses against a secondary IAV infection. Taken together, the immunomodulatory effects of progestins differentially regulate the outcome of infection depending on exposure history.IMPORTANCE The impact of hormone-based contraceptives on the outcome of infectious diseases outside the reproductive tract is rarely considered. Using a mouse model, we have made the novel observation that treatment with either progesterone or a synthetic analog found in hormonal contraceptives, levonorgestrel, impacts sequential influenza A virus infection by modulating antibody responses and decreasing the numbers and activity of memory CD8⁺ T cells. Progestins reduced the antibody responses during primary H1N1 virus infection but increased antibody titers following a sequential infection with either an H1N1 drift variant or an H3N2 virus. Following challenge with an H3N2 virus, female mice treated with progestins experienced greater mortality with increased pulmonary inflammation and reduced numbers and activity of CD8⁺ T cells. This study suggests that progestins significantly affect adaptive immune responses to influenza A virus infection, with their effect on the outcome of infection depending on exposure history.

Impact of in vitro treatments of physiological levels of estradiol and progesterone observed in pregnancy on bovine monocyte-derived dendritic cell differentiation and maturation

The specific factors which regulate differentiation and maturation of dendritic cells in bovine pregnancy remain unclear. We evaluated the influence of physiologically relevant in vitro treatments of progesterone (PG) and estradiol (E2) observed in late pregnancy on the differentiation and maturation of CD14+ monocyte-derived dendritic cell (moDC) from non-pregnant, lactating dairy cows (n=7). We found that moDC differentiated in the presence of both E2 and PG had impaired E. coli-induced phenotypic maturation, specifically a significant reduction in CD80 and MHC II expression. Contrary to our previous work characterizing moDC from late gestating dairy cattle, we did not observe an increase in CD14 expression relative to the untreated control; this increase was only observed in the current data in the dexamethasone-treated moDC. The moDC treated with a combination of both E2 and PG had significantly greater upregulation of anti-inflammatory cytokine IL-10 relative to the untreated control, but TNFα production was not suppressed; only dexamethasone-treated moDC showed abrogated TNFα production. These data suggest moDC may be regulated by E2 and PG to hinder phenotypic maturation and regulate inflammatory responses. Pregnancy-associated hormone profiles appear to be involved in the generation of maternal immune tolerance in pregnancy. These hormone-facilitated changes to moDC in pregnancy may also impede optimal immune responses to both invading pathogens and routine vaccinations administered in late gestation through limited antigen presentation and increased anti-inflammatory cytokine production. These results provide insight into maternal immune modulation and elucidate potential immune changes necessary to facilitate bovine pregnancy.