Estrogen signaling effects on muscle-specific immune responses through controlling the recruitment and function of macrophages and T cells

Sex-Based Differences in Muscle Stem Cell Regulation Following Exercise

Sexual dimorphism, driven by the sex hormones testosterone and estrogen, influences body composition, muscle fiber type, and inflammation. Research related to muscle stem cell (MuSC) responses to exercise has mainly focused on males. We propose a novel hypothesis that there are sex-based differences in MuSC regulation following exercise, such that males have more MuSCs, whereas females demonstrate a greater capacity for regeneration.

The beneficial roles and mechanisms of estrogens in immune health and infection disease

Multiple epidemiologic studies have revealed that gender is considered one of the important factors in the frequency and severity of certain infectious diseases, in which estrogens may play a vital role. There is growing evidence that estrogens as female sex hormone can modulate multiple biological functions outside of the reproductive system, such as in brain and cardiovascular system. However, it is largely unknown about the roles and mechanisms of estrogens/estrogen receptors in immune health and infection disease. Thence, by reading a lot of literature, we summarized the regulatory mechanisms of estrogens/estrogen receptors in immune cells and their roles in certain infectious diseases with gender differences. Therefore, estrogens may have therapeutic potentials to prevent and treat these infectious diseases, which needs further clinical investigation.

Spaceflight induces changes in gene expression profiles linked to insulin and estrogen

Organismal adaptations to spaceflight have been characterized at the molecular level in model organisms, including Drosophila and C. elegans. Here, we extend molecular work to energy metabolism and sex hormone signaling in mice and humans. We found spaceflight induced changes in insulin and estrogen signaling in rodents and humans. Murine changes were most prominent in the liver, where we observed inhibition of insulin and estrogen receptor signaling with concomitant hepatic insulin resistance and steatosis. Based on the metabolic demand, metabolic pathways mediated by insulin and estrogen vary among muscles, specifically between the soleus and extensor digitorum longus. In humans, spaceflight induced changes in insulin and estrogen related genes and pathways. Pathway analysis demonstrated spaceflight induced changes in insulin resistance, estrogen signaling, stress response, and viral infection. These data strongly suggest the need for further research on the metabolic and reproductive endocrinologic effects of space travel, if we are to become a successful interplanetary species.

Skeletal muscle niche, at the crossroad of cell/cell communications

Skeletal muscle is composed of a variety of tissue and non-tissue resident cells that participate in homeostasis. In particular, the muscle stem cell niche is a dynamic system, requiring direct and indirect communications between cells, involving local and remote cues. Interactions within the niche must happen in a timely manner for the maintenance or recovery of the homeostatic niche. For instance, after an injury, pro-myogenic cues delivered too early will impact on muscle stem cell proliferation, delaying the repair process. Within the niche, myofibers, endothelial cells, perivascular cells (pericytes, smooth muscle cells), fibro-adipogenic progenitors, fibroblasts, and immune cells are in close proximity with each other. Each cell behavior, membrane profile, and secretome can interfere with muscle stem cell fate and skeletal muscle regeneration. On top of that, the muscle stem cell niche can also be modified by extra-muscle (remote) cues, as other tissues may act on muscle regeneration via the production of circulating factors or the delivery of cells. In this review, we highlight recent publications evidencing both local and remote effectors of the muscle stem cell niche.

Differentiation, regulation and function of regulatory T cells in non-lymphoid tissues and tumors

Regulatory T cells (Tregs) play a substantial role in inhibiting excessive immune response. A large number of studies have focused on the tissue homeostasis maintenance and remodeling characteristics of Tregs in non-lymphoid tissues, such as the skin, colon, lung, brain, muscle, and adipose tissues. Herein, we overview the kinetics of Treg migration to non-lymphoid tissues and adaptation to the specific tissue microenvironment through the development of tissue-specific chemokine receptors, transcription factors, and phenotypes. Additionally, tumor-infiltrating Tregs (Ti-Tregs) play an important role in tumor generation and immunotherapy resistance. The phenotypes of Ti-Tregs are related to the histological location of the tumor and there is a large overlap between the transcripts of Ti-Tregs and those of tissue-specific Tregs. We recapitulate the molecular underpinnings of tissue-specific Tregs, which might shed new light on Treg-based therapeutic targets and biomarkers for inflammatory diseases and cancer.

HIV-Host Cell Interactions

The development of antiretroviral drugs (ARVs) was a great milestone in the management of HIV infection. ARVs suppress viral activity in the host cell, thus minimizing injury to the cells and prolonging life. However, an effective treatment has remained elusive for four decades due to the successful immune evasion mechanisms of the virus. A thorough understanding of the molecular interaction of HIV with the host cell is essential in the development of both preventive and curative therapies for HIV infection. This review highlights several inherent mechanisms of HIV that promote its survival and propagation, such as the targeting of CD4⁺ lymphocytes, the downregulation of MHC class I and II, antigenic variation and an envelope complex that minimizes antibody access, and how they collaboratively render the immune system unable to mount an effective response.

17beta-estradiol alleviates contusion-induced skeletal muscle injury by decreasing oxidative stress via SIRT1/PGC-1α/Nrf2 pathway

PURPOSE

This study aimed to investigate the role of 17β-estradiol (E₂) in the repair of contusion-induced myoinjury in mice and to identify the underlying molecular mechanisms.

METHODS

In vivo, contusion protocol was performed for preparing mice myoinjury model, and Injection (i.p.) of 17β-estradiol (E₂) or estrogen receptor antagonist ICI 182,780, or ovariectomy (OVX), was used to alter estrogen level of animal models. In vitro, C₂C₁₂ myoblasts were treated with H₂O₂ (oxidative stress inducer), SIRT1 inhibitor EX527, or aromatase inhibitor anastrozole. Serum E₂ level was assessed by enzyme-linked immunosorbent assay (ELISA). Muscle damage repair was evaluated by H&E staining and the activities of serum creatine kinase (CK) and lactate dehydrogenase (LDH). The oxidative stress was estimated by the levels of catalase (CAT), superoxide dismutase (SOD), and malondialdehyde (MDA). Western blot was performed to measure the protein expressions of SIRT1, PGC-1α, Nrf2, and HO-1.

RESULTS

We observed the elevated serum E₂ levels and the upregulated oxidative stress in damaged muscle in female mice after contusion-induction. The E₂ administration in vivo alleviated contusion-induced myoinjury in OVX mice by reducing CK and LDH activities, suppressing oxidative stress, and enhancing the expression levels of SIRT1, PGC-1α, Nrf2, and HO-1. These effects were inhibited by treatment with an ERα/β antagonist. Moreover, EX527 or anastrozole treatment exacerbated H₂O₂-induced growth inhibition and oxidative stress, and expression downregulation of SIRT1, PGC-1α, Nrf2, and HO-1 in C₂C₁₂ cells in vitro.

CONCLUSION

Our results suggest that E₂ is a positive intervention factor for muscle repair followed contusion-induced myoinjury, through its effects on suppressing oxidative stress via activating the SIRT1/PGC-1α/Nrf2 pathway.

Anti-tumor effect of infant-derived Enterococcus via the inhibition of proliferation and inflammation as well as the promotion of apoptosis

Probiotic Enterococcus hirae WEHI01 and Enterococcus faecium WEFA23 from infants were previously found to effectively inhibit the development of melanoma. In this study, their immunomodulatory and antitumor mechanisms were systemically studied. In vitro assay showed that E. hirae WEHI01 and E. faecium WEFA23 achieved biphasic immune regulation, which was revealed by the activation of resting spleen lymphocytes and RAW264.7 macrophages, as well as the anti-inflammation effect when immune cells were treated with LPS. The antitumor effects of E. hirae WEHI01 and E. faecium WEFA23 in vitro and vivo were then investigated. CCK8 and the cell scratch assay showed that the conditioned media, which were co-incubated with Enterococcus and spleen lymphocytes, significantly inhibited the proliferation and migration of B16F10, HepG-2 and HT-29 cells. The results of the tumor-bearing mice model experiment showed that E. faecium WEFA23 inhibition of the growth of tumors in mice, and the anti-tumor mechanism involved three aspects, namely tumor proliferation (decreasing expressions of LDHA, VEGF, MMP2, MMP9 and HIF-1α), inhibition of the pro-inflammation state (decreasing expressions of IL-6, TGF-β and IL-17) and the promotion of apoptosis (increasing expression of Bax/Bcl-2, caspase-3 and p53). The results suggest that the two strains of Enterococcus could be promising candidates for treating melanoma with a highly inhibitory effect.

Estrogen Receptor Signaling in the Immune System

The immune system functions in a sexually dimorphic manner, with females exhibiting more robust immune responses than males. However, how female sex hormones affect immune function in normal homeostasis and in autoimmunity is poorly understood. In this review, we discuss how estrogens affect innate and adaptive immune cell activity and how dysregulation of estrogen signaling underlies the pathobiology of some autoimmune diseases and cancers. The potential roles of the major circulating estrogens, and each of the 3 estrogen receptors (ERα, ERβ, and G-protein coupled receptor) in the regulation of the activity of different immune cells are considered. This provides the framework for a discussion of the impact of ER modulators (aromatase inhibitors, selective estrogen receptor modulators, and selective estrogen receptor downregulators) on immunity. Synthesis of this information is timely given the considerable interest of late in defining the mechanistic basis of sex-biased responses/outcomes in patients with different cancers treated with immune checkpoint blockade. It will also be instructive with respect to the further development of ER modulators that modulate immunity in a therapeutically useful manner.

An integrated study of hormone-related sarcopenia for modeling and comparative transcriptome in rats

Sarcopenia is a senile disease with high morbidity, serious complications and limited clinical treatments. Menopause increases the risk of sarcopenia in females, while the exact pathogenesis remains unclear. To systematically investigate the development of hormone-related sarcopenia, we established a model of sarcopenia by ovariectomy and recorded successive characteristic changes. Furthermore, we performed the transcriptome RNA sequencing and bioinformatics analysis on this model to explore the underlying mechanism. In our study, we identified an integrated model combining obesity, osteoporosis and sarcopenia. Functional enrichment analyses showed that most of the significantly enriched pathways were down-regulated and closely correlated with endocrine and metabolism, muscle dysfunction, cognitive impairment and multiple important signaling pathways. We finally selected eight candidate genes to verify their expression levels. These findings confirmed the importance of estrogen in the maintenance of skeletal muscle function and homeostasis, and provided potential targets for further study on hormone-related sarcopenia.

Use of Antiandrogens as Therapeutic Agents in COVID-19 Patients

COVID-19, caused by the severe acute respiratory syndrome coronavirus 2 (SARS CoV-2), is estimated to have caused over 6.5 million deaths worldwide. The emergence of fast-evolving SARS-CoV-2 variants of concern alongside increased transmissibility and/or virulence, as well as immune and vaccine escape capabilities, highlight the urgent need for more effective antivirals to combat the disease in the long run along with regularly updated vaccine boosters. One of the early risk factors identified during the COVID-19 pandemic was that men are more likely to become infected by the virus, more likely to develop severe disease and exhibit a higher likelihood of hospitalisation and mortality rates compared to women. An association exists between SARS-CoV-2 infectiveness and disease severity with sex steroid hormones and, in particular, androgens. Several studies underlined the importance of the androgen-mediated regulation of the host protease TMPRSS2 and the cell entry protein ACE2, as well as the key role of these factors in the entry of the virus into target cells. In this context, modulating androgen signalling is a promising strategy to block viral infection, and antiandrogens could be used as a preventative measure at the pre- or early hospitalisation stage of COVID-19 disease. Different antiandrogens, including commercial drugs used to treat metastatic castration-sensitive prostate cancer and other conditions, have been tested as antivirals with varying success. In this review, we summarise the most recent updates concerning the use of antiandrogens as prophylactic and therapeutic options for COVID-19.

Regulatory T cells-centered regulatory networks of skeletal muscle inflammation and regeneration

As the understanding of skeletal muscle inflammation is increasingly clarified, the role of Treg cells in the treatment of skeletal muscle diseases has attracted more attention in recent years. A consensus has been reached that the regulation of Treg cells is the key to completing the switch of inflammation and repair of skeletal muscle, whose presence directly determine the repairing quality of the injured skeletal muscle. However, the functioning process of Treg cells remains unreported, thereby making it necessary to summarize the current role of Treg cells in skeletal muscle. In this review, the characteristics, origins, and cellular kinetics of these Treg cells are firstly described; Then, the relationship between Treg cells and muscle satellite cells (MuSCs), conventional T cells (Tconv) is discussed (the former is involved in the entire repair and regeneration process, while the latter matters considerably in causing most skeletal muscle autoimmune diseases); Next, focus is placed on the control of Treg cells on the phenotypic switch of macrophages, which is the key to the switch of inflammation; Finally, factors regulating the functional process of Treg cells are analyzed, and a regulatory network centered on Treg cells is summarized. The present study summarizes the cell-mediated interactions in skeletal muscle repair over the past decade, and elucidates the central role of regulatory T cells in this process, so that other researchers can more quickly and comprehensively understand the development and direction of this very field. It is believed that the hereby proposed viewpoints and problems can provide fresh visions for the latecomers.

Essential roles of the cytokine oncostatin M in crosstalk between muscle fibers and immune cells in skeletal muscle after aerobic exercise

Crosstalk between muscle fibers and immune cells is well known in the processes of muscle repair after exercise, especially resistance exercise. In aerobic exercise, however, this crosstalk is not fully understood. In the present study, we found that macrophages, especially anti-inflammatory (M2) macrophages, and neutrophils accumulated in skeletal muscles of mice 24 h after a single bout of an aerobic exercise. The expression of oncostatin M (OSM), a member of the interleukin 6 family of cytokines, was also increased in muscle fibers immediately after the exercise. In addition, we determined that deficiency of OSM in mice inhibited the exercise-induced accumulation of M2 macrophages and neutrophils, whereas intramuscular injection of OSM increased these immune cells in skeletal muscles. Furthermore, the chemokines related to the recruitment of macrophages and neutrophils were induced in skeletal muscles after aerobic exercise, which were attenuated in OSM-deficient mice. Among them, CC chemokine ligand 2, CC chemokine ligand 7, and CXC chemokine ligand 1 were induced by OSM in skeletal muscles. Next, we analyzed the direct effects of OSM on the skeletal muscle macrophages, because the OSM receptor β subunit was expressed predominantly in macrophages in the skeletal muscle. OSM directly induced the expression of these chemokines and anti-inflammatory markers in the skeletal muscle macrophages. From these findings, we conclude that OSM is essential for aerobic exercise-induced accumulation of M2 macrophages and neutrophils in the skeletal muscle partly through the regulation of chemokine expression in macrophages.

Skeletal Muscle Regeneration in Cardiotoxin-Induced Muscle Injury Models

Skeletal muscle injuries occur frequently in daily life and exercise. Understanding the mechanisms of regeneration is critical for accelerating the repair and regeneration of muscle. Therefore, this article reviews knowledge on the mechanisms of skeletal muscle regeneration after cardiotoxin-induced injury. The process of regeneration is similar in different mouse strains and is inhibited by aging, obesity, and diabetes. Exercise, microcurrent electrical neuromuscular stimulation, and mechanical loading improve regeneration. The mechanisms of regeneration are complex and strain-dependent, and changes in functional proteins involved in the processes of necrotic fiber debris clearance, M1 to M2 macrophage conversion, SC activation, myoblast proliferation, differentiation and fusion, and fibrosis and calcification influence the final outcome of the regenerative activity.

The importance of biological sex in cardiac cachexia

Cardiac cachexia is a catabolic muscle wasting syndrome observed in approximately 1 in 10 heart failure patients. Increased skeletal muscle atrophy leads to frailty and limits mobility which impacts quality of life, exacerbates clinical care, and is associated with higher rates of mortality. Heart failure is known to exhibit a wide range of prevalence and severity when examined across individuals of different ages and with co-morbidities related to diabetes, renal failure and pulmonary dysfunction. It is also recognized that men and women exhibit striking differences in the pathophysiology of heart failure as well as skeletal muscle homeostasis. Given that both skeletal muscle and heart failure physiology are in-part sex dependent, the diagnosis and treatment of cachexia in heart failure patients may depend on a comprehensive examination of how these organs interact. In this review we explore the potential for sex-specific differences in cardiac cachexia. We summarize advantages and disadvantages of clinical methods used to measure muscle mass and function and provide alternative measurements that should be considered in preclinical studies. Additionally, we summarize sex-dependent effects on muscle wasting in preclinical models of heart failure, disuse, and cancer. Lastly, we discuss the endocrine function of the heart and outline unanswered questions that could directly impact patient care.

Regulatory T cells in skeletal muscle repair and regeneration: recent insights

Skeletal muscle repair and regeneration after injury is a multi-stage process, involving a dynamic inflammatory microenvironment consisting of a complex network formed by the interaction of immune cells and their secreted cytokines. The homeostasis of the inflammatory microenvironment determines whether skeletal muscle repair tissues will ultimately form scar tissue or regenerative tissue. Regulatory T cells (Tregs) regulate homeostasis within the immune system and self-immune tolerance, and play a crucial role in skeletal muscle repair and regeneration. Dysregulated Tregs function leads to abnormal repair. In this review, we discuss the role and mechanisms of Tregs in skeletal muscle repair and regeneration after injury and provide new strategies for Treg immunotherapy in skeletal muscle diseases.

Mechanisms of Estrogen Influence on Skeletal Muscle: Mass, Regeneration, and Mitochondrial Function

Human menopause is widely associated with impaired skeletal muscle quality and significant metabolic dysfunction. These observations pose significant challenges to the quality of life and mobility of the aging population, and are of relevance when considering the significantly greater losses in muscle mass and force-generating capacity of muscle from post-menopausal females relative to age-matched males. In this regard, the influence of estrogen on skeletal muscle has become evident across human, animal, and cell-based studies. Beneficial effects of estrogen have become apparent in mitigation of muscle injury and enhanced post-damage repair via various mechanisms, including prophylactic effects on muscle satellite cell number and function, as well as membrane stability and potential antioxidant influences following injury, exercise, and/or mitochondrial stress. In addition to estrogen replacement in otherwise deficient states, exercise has been found to serve as a means of augmenting and/or mimicking the effects of estrogen on skeletal muscle function in recent literature. Detailed mechanisms behind the estrogenic effect on muscle mass, strength, as well as the injury response are beginning to be elucidated and point to estrogen-mediated molecular cross talk amongst signalling pathways, such as apoptotic signaling, contractile protein modifications, including myosin regulatory light chain phosphorylation, and the maintenance of muscle satellite cells. This review discusses current understandings and highlights new insights regarding the role of estrogen in skeletal muscle, with particular regard to muscle mass, mitochondrial function, the response to muscle damage, and the potential implications for human physiology and mobility.

Association of severity and mortality of Covid-19 cases among acute kidney injury and sexual dimorphism

Introduction

The outbreak of coronavirus disease 2019 (Covid-19) severely impacted global health and economic status. The native receptor-ligand interaction of Angiotensin-converting enzyme 2 (ACE2) and S protein induces host cell pathogenesis via immunosuppression.

Material and Methods

The emerging evidence reports the sex disparity in Covid-19 induced mortality rate which affects abundantly men population. Although the biological interaction of Covid-19 with receptor upregulates the viral genome protein interactions and initiates the predictive multiorgan failure followed by acute kidney injury (AKI) in Covid-19 infected male population.

Conclusion

Besides, the knowledge and lessons learned from the study depict that cellular and molecular links may explain the risk and severity of Covid-19 and AKI in the male population and lead to management of Covid-19 induced AKI. Therefore, this review explored the pathways associated with the pathogenesis of two diseased conditions with sex disparity.

Skeletal muscle wasting: the estrogen side of sexual dimorphism

The importance of defining sex differences across various biological and physiological mechanisms is more pervasive now than it has been over the past 15-20 years. As the muscle biology field pushes to identify small molecules and interventions to prevent, attenuate, or even reverse muscle wasting, we must consider the effect of sex as a biological variable. It should not be assumed that a therapeutic will affect males and females with equal efficacy or equivalent target affinities under conditions where muscle wasting is observed. With that said, it is not surprising to find that we have an unclear or even a poor understanding of the effects of sex or sex hormones on muscle wasting conditions. Although recent investigations are beginning to establish experimental approaches that will allow investigators to assess the impact of sex-specific hormones on muscle wasting, the field still needs rigorous scientific tools that will allow the community to address critical hypotheses centered around sex hormones. The focus of this review is on female sex hormones, specifically estrogens, and the roles that these hormones and their receptors play in skeletal muscle wasting conditions. With the overall review goal of assembling the current knowledge in the area of sexual dimorphism driven by estrogens with an effort to provide insights to interested physiologists on necessary considerations when trying to assess models for potential sex differences in cellular and molecular mechanisms of muscle wasting.

The Renin-Angiotensin-Aldosterone System in Postmenopausal Women: The Promise of Hormone Therapy

Estradiol (E2) plays an underrecognized role in modulating body-wide systems, including important interactions with the renin-angiotensin-aldosterone system (RAAS). The RAAS is an immunomodulating system that is critical for maintaining homeostasis across multiple organ systems. The diverse interactions between E2 and the RAAS help maintain cardiometabolic homeostasis, including successful physiologic responses to trauma and infectious pathogens. Estradiol deficiency (ie, menopause) results in impaired responses and increased susceptibility to infectious pathogens. Both immune and cardiometabolic function decline with reduced E2 production, in part because the RAAS becomes dysregulated by E2 deficiency, leaving RAAS predominantly in its proinflammatory state and predisposing to systemic low-grade inflammation. Estradiol deficiency and RAAS dysregulation contribute to impaired immune responses and increased incidence of cardiac hypertrophy, hypertension, atherosclerotic cardiovascular disease, arrhythmias, and heart failure. The RAAS consists of dual, counterbalancing pathways-proinflammatory and anti-inflammatory. Estradiol is a signaling agent that plays a major role in determining which RAAS pathway predominates. The proinflammatory pathway is activated early in response to infection or trauma, followed by up-regulation of the anti-inflammatory pathway, to resolve inflammation and to restore homeostasis. Estradiol influences activation of the "switch" to restore the anti-inflammatory state. The dysregulated RAAS is a primary target of current cardiovascular therapeutics focused on blocking portions of its proinflammatory pathway. However, RAAS-modifying pharmaceuticals often provide imperfect solutions to these physiologic disruptions and underscore the need for improved approaches to menopausal medicine. Estradiol therapy and optimal lifestyle practices combined with RAAS-modifying pharmaceuticals may be an ideal strategy to optimize postmenopausal health.

Estrogen modulates the skeletal muscle regeneration process and myotube morphogenesis: morphological analysis in mice with a low estrogen status

The purpose of this study was to elucidate the functions of estrogen and two estrogen receptors (ERs; ERα and ERβ) in the myoregeneration process and morphogenesis. Cardiotoxin (CTX) was injected into the tibialis anterior (TA) muscles of ovariectomized (OVX) mice to induce muscle injury, and subsequent myoregeneration was morphologically assessed. The diameter of regenerated myotubes in OVX mice was significantly smaller than that in intact mice at all time points of measurement. OVX mice also showed lower muscle recovery rates and slower speeds than did intact mice. ER protein levels showed a predominance of ERβ over ERα in both intact and OVX states. The ERβ level was increased significantly at 7 days after CTX injection in OVX mice and remained at a high level until 14 days. In addition, continuous administration of E2 to OVX mice in which muscle injury was induced resulted in a significantly larger diameter of regenerated myotubes than that in mice that did not receive estrogen. The results indicate that estrogen is an essential factor in the myoregeneration process since estrogen depletion delayed myoregeneration in injured muscles and administration of estrogen under the condition of a low estrogen status rescued delayed myoregeneration. The results strongly suggested that ERβ may be a factor that promotes myoregeneration more than does ERα.

Estrogen receptor β alleviates inflammatory lesions in a rat model of inflammatory bowel disease via down-regulating P2X7R expression in macrophages

Estrogen receptor beta (ERβ) agonists could inhibit inflammation in animal models of inflammatory bowel disease (IBD). However, the mechanism underlying such effect and the potential role of P2 × 7 receptor (P2X7R) remains unclear. In the present study, we examined whether the effect of ERβ activation in IBD rats was related to P2X7R. Overexpression of ERβ using a recombinant lentivirus in IBD rats improved the IBD-like symptoms, including weight loss, disease activity index (DAI) scores, and inflammatory responses. ERβ agonists DPN and ERB-041 attenuated P2X7R expression in macrophages from colitis rats and in a murine macrophage cell line (RAW264.7) in response to either lipopolysaccharide (LPS) or adenosine triphosphate (ATP). DPN and ERB-041 also blocked increased production of TNF-α, IL-6, and IL-1β in the rectocolon of colitis rats. The two ERβ agonists reversed LPS- and ATP-induced up-regulation of P2X7R and its downstream proteins, including NLRP3, ASC, caspase-1, and pro-IL-1β, in RAW264.7 cells. Also, in both the rectocolon of colitis rats and RAW264.7 cells, ERβ agonists reversed the up-regulation of extracellular regulated protein kinases (ERK), the Janus kinase 2 (JAK2), and signal transducer and activator of transcription 3 (STAT3), but not up-regulation of serine threonine kinase or cAMP-response element binding protein (CREB). Blockade of JAK2 or STAT3 phosphorylation significantly reduced the ability of DPN to down-regulate P2X7R expression and the ability of ERB-041 and DPN to inhibit IL-1β release from RAW264.7 cells. We found that ERβ and P2X7R co-localized in the macrophages of rat rectocolon and in RAW264.7 cells. Deletion of macrophages from colitis rats with clodronate abolished the inhibitory effect of DPN. These results suggest that ERβ plays an important anti-inflammatory role in IBD rats by down-regulating P2X7R expression and inhibiting IL-1β release from macrophages through the JAK2/STAT3 signaling pathway.

Differential effects of estradiol and progesterone on human T cell activation in vitro

Estradiol (E2) and progesterone (P4) are steroid hormones important for the regulation of immune responses during pregnancy. Their increasing levels coincide with an improvement of T cell-mediated diseases such as multiple sclerosis (MS). Although immune-endocrine interactions are involved in this phenomenon, the relative contribution of hormones is not known. We here report a direct comparison of E2- and P4-mediated effects on human CD4⁺ T cells, key cells in immune regulation. T cells were stimulated to obtain different activation levels and exposed to a broad range of hormone concentrations. Activation level was assessed by CD69/CD25 expression by flow cytometry, and secreted proteins (n = 196) were measured in culture supernatants using proximity extension assay and electrochemiluminescence immunoassay. We found that in low activated cells, pregnancy-relevant E2 concentrations increased activation and the secretion of several immune- and inflammation-related proteins. P4, on the other hand, showed a biphasic pattern, where serum-related concentrations upregulated activation and protein secretion while placenta-relevant concentrations induced a prominent dampening irrespective of the initial activation level. Our results demonstrate the importance of P4 as a major hormone in the immune modulation of T cells during pregnancy and emphasize the need to further evaluate its potency in the treatment of diseases like MS.

Tamoxifen Suppresses the Immune Response to Plasmodium berghei ANKA and Exacerbates Symptomatology

Malaria is the most lethal parasitic disease in the world. Mortality and severity in symptoms are higher in men than women, suggesting that oestrogens, which are in higher concentration in females than in males, may regulate the immune response against malaria. Tamoxifen, a selective oestrogen receptor modulator used in breast cancer treatment due to its antagonistic effect on oestrogen receptors α and β, is also studied because of its potential therapeutic use for several parasitic diseases. However, most studies, including one in malaria, have not addressed the immunomodulatory role of tamoxifen. In this work, we evaluated the effect of tamoxifen on the immune response of CBA/Ca mice against Plasmodium berghei ANKA. This study showed for the first time that tamoxifen increased parasite load, aggravated symptoms by decreasing body temperature and body weight, and worsened anaemia. Additionally, tamoxifen significantly increased the splenic index and the percentages of CD4⁺ and NK⁺ cells on day eight post-infection. By contrast, tamoxifen decreased both CD8⁺ and B220⁺ populations in the spleen and decreased the serum levels of IL-2, IL-6, and IL-17. Our findings support the notion that tamoxifen is a potent immunomodulator in malaria-infected mice and suggest caution when administering it to malaria-infected women with breast cancer.

The effect of estrogen in coronavirus disease 2019

The outcomes of coronavirus disease 2019 (COVID-19) vary between men and women. Some statistical reports have shown that men have a higher risk of developing COVID-19 and suffer from worse outcomes than females. Although there are many factors that can explain the high prevalence of COVID-19 in men, such as lifestyle habits and the different profile of comorbidities among sexes, the distinctions between male and female immune systems cannot be ignored. It has been sufficiently shown that sex differences have a critical influence on the shaping of immune response, which then leads to different pathogenesis in infectious diseases. Compared with males, females typically have a more effective innate and adaptive immune response to viral infections in COVID-19. What’s more, there is a growing body of evidence showing that estrogen exerts an effect on the regulation of immune response. This article examines the effect and mechanism of estrogen on COVID-19.

Newer insights into the pathobiological and pharmacological basis of the sex disparity in patients with pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) affects more women than men, although affected females tend to survive longer than affected males. This sex disparity in PAH is postulated to stem from the diverse roles of sex hormones in disease etiology. In animal models, estrogens appear to be implicated not only in pathologic remodeling of pulmonary arteries, but also in protection against right ventricular (RV) hypertrophy. In contrast, the male sex hormone testosterone is associated with reduced survival in male animals, where it is associated with increased RV mass, volume, and fibrosis. However, it also has a vasodilatory effect on pulmonary arteries. Furthermore, patients of both sexes show varying degrees of response to current therapies for PAH. As such, there are many gaps and contradictions regarding PAH development, progression, and therapeutic interventions in male versus female patients. Many of these questions remain unanswered, which may be due in part to lack of effective experimental models that can consistently reproduce PAH pulmonary microenvironments in their sex-specific forms. This review article summarizes the roles of estrogens and related sex hormones, immunological and genetical differences, and the benefits and limitations of existing experimental tools to fill in gaps in our understanding of the sex-based variation in PAH development and progression. Finally, we highlight the potential of a new tissue chip-based model mimicking PAH-afflicted male and female pulmonary arteries to study the sex-based differences in PAH and to develop personalized therapies based on patient sex and responsiveness to existing and new drugs.

Deregulated estrogen receptor signaling and DNA damage response in breast tumorigenesis

Carriers of BRCA1 mutations have a higher chance of developing cancers in hormone-responsive tissues like the breast, ovary and prostate, compared to other tissues. These tumors generally exhibit basal-like characters and do not express estrogen receptor (ER) or progesterone receptor (PR). Intriguingly, BRCA1 mutated breast cancers have a less favorable clinical outcome, as they will not respond to hormone therapy. BRCA1 has been reported to exhibit ligand dependent and independent transcriptional inhibition of ER-α; however, there exists a controversy on whether BRCA1 induces or inhibits ER-α expression. The mechanisms associated with resistance of BRCA1 mutated cancers to hormone therapy, as well as the tissue restriction exhibited by BRCA1 mutated tumors are still largely unknown. BRCA1 mutated tumors possess increased DNA damages and decreased genomic integrity, as BRCA1 plays a cardinal role in high fidelity DNA damage repair pathways, like homologous recombination (HR). The existence of cross regulatory signaling networks between ER-α and BRCA1 speculates a role of ER on BRCA1 dependent DDR pathways. Thus, the loss or haploinsufficiency of BRCA1 and the consequential deregulation of ER-α signaling may result in persistence of unrepaired DNA damages, eventually leading to tumorigenesis. Therefore, understanding of this cross-talk between ER-α and BRCA1, with regard to DDR, will provide critical insights to steer drug development and therapy for breast/ovarian cancers. This review discusses the mechanisms by which estrogen and ER signaling influence BRCA1 mediated DNA damage response and repair pathways in the mammalian system.

Neuroimmunomodulation by estrogen in health and disease

Systemic homeostasis is maintained by the robust bidirectional regulation of the neuroendocrine-immune network by the active involvement of neural, endocrine and immune mediators. Throughout female reproductive life, gonadal hormones undergo cyclic variations and mediate concomitant modulations of the neuroendocrine-immune network. Dysregulation of the neuroendocrine-immune network occurs during aging as a cumulative effect of declining neural, endocrine and immune functions and loss of compensatory mechanisms including antioxidant enzymes, growth factors and co-factors. This leads to disruption of homeostasis and sets the stage for the development of female-specific age-associated diseases such as autoimmunity, osteoporosis, cardiovascular diseases and hormone-dependent cancers. Ovarian hormones especially estrogen, play a key role in the maintenance of health and homeostasis by modulating the nervous, endocrine and immune functions and thereby altering neuroendocrine-immune homeostasis. Immunologically estrogen's role in the modulation of Th1/Th2 immune functions and contributing to pro-inflammatory conditions and autoimmunity has been widely studied. Centrally, hypothalamic and pituitary hormones influence gonadal hormone secretion in murine models during onset of estrous cycles and are implicated in reproductive aging-associated acyclicity. Loss of estrogen affects neuronal plasticity and the ensuing decline in cognitive functions during reproductive aging in females implicates estrogen in the incidence and progression of neurodegenerative diseases. Peripherally, sympathetic noradrenergic (NA) innervations of lymphoid organs and the presence of both adrenergic (AR) and estrogen receptors (ER) on lymphocytes poise estrogen as a potent neuroimmunomodulator during health and disease. Cyclic variations in estrogen levels throughout reproductive life, perimenopausal surge in estrogen levels followed by its precipitous decline, concomitant with decline in central hypothalamic catecholaminergic activity, peripheral sympathetic NA innervation and associated immunosuppression present an interesting study to explore female-specific age-associated diseases in a new light.

Could Estrogen Protect Women From COVID-19?

The apparent gender differences in favor of women in the risk of contracting and dying from coronavirus disease 2019 (COVID-19), and the fact that such trends have also been observed in recent epidemics including severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), have prompted the obvious question: Are the reasons life-style or biological? True, women generally make healthier lifestyle choices as compared to men. Women do not smoke or drink as much as men, and they have a lower burden of those diseases (heart disease, diabetes or chronic lung conditions) that are known to be significant factors in the higher death rates among men with COVID-19. But there is compelling evidence for a role for biological factors. Genes are likely to play an important role. The X chromosome, of which women possess two, contains the largest number of immune-related genes of the whole human genome, theoretically giving women double the advantage over men in mounting an efficient and rapid immune response. A fundamental difference between women and men is their hormonal milieu, and it is not unreasonable to suppose that the dominant female hormone estrogen could influence the response to infection. In this paper we evaluate the evidence and mechanisms by which estrogen could provide protection to women from a variety of viruses, perhaps including the coronavirus that causes COVID-19.

Learning from Monocyte-Macrophage Fusion and Multinucleation: Potential Therapeutic Targets for Osteoporosis and Rheumatoid Arthritis

Excessive bone resorption by osteoclasts (OCs) covers an essential role in developing bone diseases, such as osteoporosis (OP) and rheumatoid arthritis (RA). Monocytes or macrophages fusion and multinucleation (M-FM) are key processes for generating multinucleated mature cells with essential roles in bone remodelling. Depending on the phenotypic heterogeneity of monocyte/macrophage precursors and the extracellular milieu, two distinct morphological and functional cell types can arise mature OCs and giant cells (GCs). Despite their biological relevance in several physiological and pathological responses, many gaps exist in our understanding of their formation and role in bone, including the molecular determinants of cell fusion and multinucleation. Here, we outline fusogenic molecules during M-FM involved in OCs and GCs formation in healthy conditions and during OP and RA. Moreover, we discuss the impact of the inflammatory milieu on modulating macrophages phenotype and their differentiation towards mature cells. Methodological approach envisaged searches on Scopus, Web of Science Core Collection, and EMBASE databases to select relevant studies on M-FM, osteoclastogenesis, inflammation, OP, and RA. This review intends to give a state-of-the-art description of mechanisms beyond osteoclastogenesis and M-FM, with a focus on OP and RA, and to highlight potential biological therapeutic targets to prevent extreme bone loss.

Maresin1 Promotes M2 Macrophage Polarization Through Peroxisome Proliferator-Activated Receptor-γ Activation to Expedite Resolution of Acute Lung Injury

BACKGROUND

Acute lung injury (ALI), manifested by progressive hypoxemia and respiratory distress, is associated with high morbidity and mortality, which lacks the effective therapies in clinics. Our previous studies demonstrated that maresin1 (MaR1), a specialized proresolving mediator, could effectively mitigate the inflammation of lipopolysaccharide (LPS)-induced ALI. However, whether MaR1 impacts the macrophage polarization to alleviate ALI remains unclear. Our study explored the effects and underlying mechanisms of MaR1 on the macrophage phenotypes in ALI.

MATERIAL AND METHODS

Male BALB/c mice were subjected to endotracheal instillation of LPS to induce ALI and then intravenously injected with MaR1 or normal saline. Intraperitoneal administration of peroxisome proliferator-activated receptor-γ (PPAR-γ) inhibitor GW9662 was given 30 mins before MaR1. We measured the pathohistologic changes, pulmonary edema, inflammatory cytokines, and the flow cytometry of macrophage phenotypes.

RESULTS

Our results illustrated that MaR1 ameliorated lung injury and increased monocyte or macrophage recruitment and the release of anti-inflammatory cytokines. The flow cytometry showed that MaR1 promoted polarization of CD11c^-CD206⁺ (M2) macrophages and inhibited polarization of CD11c⁺CD206^- (M1) macrophages. Besides, the western blotting revealed that MaR1 increased the expression of PPAR-γ. The pretreatment with PPAR-γ antagonist GW9662 could significantly suppress the polarization of M2 macrophages and antagonize the protective effects of MaR1 on LPS-stimulated ALI.

CONCLUSIONS

MaR1 was able to promote M2 macrophage polarization by reversing LPS-mediated PPAR-γ inhibition, thereby expediting the recovery of LPS-stimulated ALI.

Sex differences in SARS-CoV-2 infection rates and the potential link to prostate cancer

The recent outbreak of infections and the pandemic caused by SARS-CoV-2 represent one of the most severe threats to human health in more than a century. Emerging data from the United States and elsewhere suggest that the disease is more severe in men. Knowledge gained, and lessons learned, from studies of the biological interactions and molecular links that may explain the reasons for the greater severity of disease in men, and specifically in the age group at risk for prostate cancer, will lead to better management of COVID-19 in prostate cancer patients. Such information will be indispensable in the current and post-pandemic scenarios.

Advance in Drug Delivery for Ageing Skeletal Muscle

The age-related loss of skeletal muscle, sarcopenia, is characterized by progressive loss of muscle mass, reduction in muscle strength, and dysfunction of physical performance. It has become a global health problem leading to several adverse outcomes in the ageing population. Research on skeletal muscle loss prevention and treatment is developing quickly. However, the current clinical approaches to sarcopenia are limited. Recently, novel drug delivery systems offer new possibilities for treating aged muscle loss. Herein, we briefly recapitulate the potential therapeutic targets of aged skeletal muscle and provide a concise advance in the drug delivery systems, mainly focus on the use of nano-carriers. Furthermore, we elaborately discuss the prospect of aged skeletal muscle treatment by nanotechnology approaches.

Role of Regulatory T Cells in Regulating Fetal-Maternal Immune Tolerance in Healthy Pregnancies and Reproductive Diseases

Regulatory T cells (Tregs) are a specialized subset of T lymphocytes that function as suppressive immune cells and inhibit various elements of immune response in vitro and in vivo. While there are constraints on the number or function of Tregs which can be exploited to evoke an effective anti-tumor response, sufficient expansion of Tregs is essential for successful organ transplantation and for promoting tolerance of self and foreign antigens. The immune-suppressive property of Tregs equips this T lymphocyte subpopulation with a pivotal role in the establishment and maintenance of maternal tolerance to fetal alloantigens, which is necessary for successful pregnancy. Elevation in the level of pregnancy-related hormones including estrogen, progesterone and human chorionic gonadotropin promotes the recruitment and expansion of Tregs, directly implicating these cells in the regulation of fetal-maternal immune tolerance. Current studies have provided evidence that a defect in the number or function of Tregs contributes to the etiology of several reproductive diseases, such as recurrent spontaneous abortion, endometriosis, and pre-eclampsia. In this review, we provide insight into the underlying mechanism through which Tregs contribute to pregnancy-related immune tolerance and demonstrate the association between deficiencies in Tregs and the development of reproductive diseases.

Mouse testicular transcriptome after modulation of non-canonical oestrogen receptor activity

The aims of this study were to shed light on the role of G-protein-coupled membrane oestrogen receptor (GPER) and oestrogen-related receptor (ERR) in mouse testis function at the gene expression level, as well as the involvement of GPER and ERR in cellular and molecular processes. Male mice were injected (50µg kg-1,s.c.) with the GPER antagonist G-15, the ERRα inverse agonist XCT790 or the ERRβ/ERRγ agonist DY131. Next-generation sequencing (RNA-Seq) was used to evaluate gene expression. Bioinformatic analysis of read abundance revealed that 50, 86 and 171 transcripts were differentially expressed in the G-15-, XCT790- and DY131-treated groups respectively compared with the control group. Annotated genes and their protein products were categorised regarding their associated biological processes and molecular functions. In the XCT790-treated group, genes involved in immunological processes were upregulated. In the DY131-treated group, genes with increased expression were primarily engaged in protein modification (protein folding and small protein conjugation). In addition, the expression of genes recognised as oncogenes, such as BMI1 proto-oncogene, polycomb ring finger (Bmi1) and nucleophosphin 1 (Npm1), was significantly increased in all experimental groups. This study provides detailed information regarding the genetic changes in the testicular transcriptome of the mouse in response to modulation of non-canonical oestrogen receptor activity.