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

Reconsidering Gender in Asthma: Is It All About Sex? A Perspective Review

Asthma is a prevalent chronic condition, affecting an estimated 260 million people worldwide, according to the 2021 Global Burden of Disease Study. This condition significantly impacts individuals of all ages. One notable finding is that asthma prevalence among adults was higher in females than males. Recent evidence suggests that these disparities in asthma prevalence and outcomes are likely due to complex interactions among hormonal, anatomical, and environmental factors, coupled with societal and behavioral influences. The interchangeable use of the terms "sex" and "gender" in the scientific literature is frequently inconsistent. Biological sex is defined by anatomical and physiological characteristics determined by genetics; "gender", on the other hand, is a more complex construct and a universally accepted definition is still lacking. This lack of clarity, coupled with potential knowledge gaps, misunderstandings, or the inherent difficulty in differentiating sex- and gender-related effects, often leads to the terms being poorly defined or used interchangeably. Such imprecise usage hinders accurate data interpretation and research progress. This paper provides a perspective review synthesizing current knowledge regarding the influence of sex and gender on asthma, specifically focusing on their impact on disease pathogenesis, clinical presentation, severity, and management strategies.

Interplay between endogenous hormones and immune systems in human metapneumovirus pathogenesis and management

The present review explores the role of endogenous hormones, such as cortisol, melatonin, thyroid hormones, sex hormones, and insulin, in the modulation of the immune response to a human metapneumovirus (hMPV) infection. hMPV is a respiratory pathogen responsible for severe infections, particularly in vulnerable populations like children and the elderly. The virus triggers inflammatory responses through various molecular processes, including cytokine production and immune signaling pathways. Notably, these processes can be influenced by endocrine factors, such as hormones. Cortisol, through hypothalamic-pituitary-adrenal (HPA) axis activation, modulates inflammation but may contribute to immunosuppression. Melatonin inhibits the NLRP3 inflammasome, reducing lung inflammation. Thyroid hormones regulate immune responses via nuclear factor kappa B (NF-κB) and JAK/STAT pathways, while hypothyroidism may alter infection severity. Sex hormones, particularly estrogens, enhance antiviral immunity, whereas androgens may have variable effects on immune modulation. Insulin influences inflammation through NF-κB suppression, with insulin resistance potentially worsening viral pathogenesis. Therapeutic implications suggest that modulating these hormonal pathways could aid in hMPV management. Strategies such as hormone therapy, glucocorticoid regulation, and nanoparticle-based drug delivery are potential routes of intervention. The aim of the present review is to understand the complex interplay between endogenous hormones and the immune system during an hMPV infection by describing the complex molecular mechanisms associated with these processes.

Exploring the Contribution of TLR7 to Sex-Based Disparities in Respiratory Syncytial Virus (RSV)-Induced Inflammation and Immunity

TLR7 plays a key role in recognizing viral RNA to initiate an immune response. Sex-based differences in the severity of RSV respiratory infections have been noted, and this may be related to higher expression of X-linked toll-like receptor 7 (TLR7) in female immune cells. Indeed, TLR7 has been shown to influence sex differences in responses to other respiratory viruses; however, its role in RSV infection remains underexplored. We infected adult C57Bl/6 or TLR7 knockout mice with RSV and compared the specific lung immune responses between different sexes. Gene expression analysis revealed that infected female mice had elevated levels of type I and II interferons, proinflammatory cytokines, chemokines, and viral transcripts in their lungs compared to males. Additionally, females exhibited increased numbers of macrophages and higher antibody responses in the airways. Deletion of TLR7 diminished the sex differences in certain cytokine and antibody responses. Furthermore, ex vivo infection of male alveolar macrophages with RSV resulted in greater production of proinflammatory cytokines and viral transcripts than in female macrophages, suggesting inherent sex differences in macrophage responses. These findings provide new insights into the mechanisms underlying sex differences in RSV pathophysiology and suggest that TLR7 contributes to an enhanced inflammatory response in females.

ANDROGENS PROTECT ILC2S FROM FUNCTIONAL SUPPRESSION DURING INFLUENZA VIRUS INFECTION

Biological sex differences in morbidity upon influenza A virus (IAV) infection are linked to stronger IFN-centered immune responses in females, yet the regulatory role of sex hormone receptors in immune cell subsets is incompletely understood. Lung-resident group 2 innate lymphoid cells (ILC2s) express notably high levels of androgen receptors (AR). In IAV infection, ILC2s produce type 2 cytokines and facilitate tissue repair, but they also may be functionally suppressed by type 1 cytokines. Here we report sex differences in the magnitude of lung ILC2 functional suppression at the peak of sublethal IAV infection. Relative to males, ILC2s in females show attenuated proliferation, decreased propensity for IL-5 and amphiregulin production and reduced expression of GATA3 and IL-33R, features supported by divergent transcriptomes. Equivalent inflammatory cytokine levels and viral load suggested sex differences in ILC2-intrinsic factors. Indeed, naïve female ILC2s showed elevated IFNGR expression and higher phospho-STAT1 levels following IFNγ stimulation, and lymphocyte-restricted STAT1 deficiency reversed IAV-induced suppression of female ILC2s. Lymphocyte-restricted AR deficiency or loss of androgens via orchiectomy led to increased IFNGR expression and suppression of male ILC2s. These data support the hypothesis that intrinsic AR activity regulates IFNGR-STAT1 signaling pathways to preserve canonical ILC2 function in males during IAV infection.

Exploring How Adipose Tissue, Obesity, and Gender Influence the Immune Response to Vaccines: A Comprehensive Narrative Review

Vaccines represent an essential tool for the prevention of infectious diseases. Upon administration, a complex interaction occurs between the vaccine formulation and the recipient's immune system, ultimately resulting in protection against disease. Significant variability exists in individual and population responses to vaccination, and these differences remain the focus of the ongoing research. Notably, well-documented factors, such as age, gender, and genetic predisposition, influence immune responses. In contrast, the effects of overweight and obesity have not been as thoroughly investigated. The evidence indicates that a high body mass index (BMI) constitutes a significant risk factor for infections in general, with adipose tissue playing a crucial role in modulating the immune response. Furthermore, suboptimal levels of vaccine seroconversion have been observed among individuals with obesity. This review provides a plausible examination of the immunity and protection conferred by various vaccines in individuals with an overweight status, offering a comprehensive analysis of the mechanisms to enhance vaccination efficiency.

Sex Differences in Long COVID

Importance

A substantial number of individuals worldwide experience long COVID, or post-COVID condition. Other postviral and autoimmune conditions have a female predominance, but whether the same is true for long COVID, especially within different subgroups, is uncertain.

Objective

To evaluate sex differences in the risk of developing long COVID among adults with SARS-CoV-2 infection.

Design, Setting, and Participants

This cohort study used data from the National Institutes of Health (NIH) Researching COVID to Enhance Recovery (RECOVER)-Adult cohort, which consists of individuals enrolled in and prospectively followed up at 83 sites in 33 US states plus Washington, DC, and Puerto Rico. Data were examined from all participants enrolled between October 29, 2021, and July 5, 2024, who had a qualifying study visit 6 months or more after their initial SARS-CoV-2 infection.

Exposure

Self-reported sex (male, female) assigned at birth.

Main Outcomes and Measures

Development of long COVID, measured using a self-reported symptom-based questionnaire and scoring guideline at the first study visit that occurred at least 6 months after infection. Propensity score matching was used to estimate risk ratios (RRs) and risk differences (95% CIs). The full model included demographic and clinical characteristics and social determinants of health, and the reduced model included only age, race, and ethnicity.

Results

Among 12 276 participants who had experienced SARS-CoV-2 infection (8969 [73%] female; mean [SD] age at infection, 46 [15] years), female sex was associated with higher risk of long COVID in the primary full (RR, 1.31; 95% CI, 1.06-1.62) and reduced (RR, 1.44; 95% CI, 1.17-1.77) models. This finding was observed across all age groups except 18 to 39 years (RR, 1.04; 95% CI, 0.72-1.49). Female sex was associated with significantly higher overall long COVID risk when the analysis was restricted to nonpregnant participants (RR, 1.50; 95%: CI, 1.27-1.77). Among participants aged 40 to 54 years, the risk ratio was 1.42 (95% CI, 0.99-2.03) in menopausal female participants and 1.45 (95% CI, 1.15-1.83) in nonmenopausal female participants compared with male participants.

Conclusions and Relevance

In this prospective cohort study of the NIH RECOVER-Adult cohort, female sex was associated with an increased risk of long COVID compared with male sex, and this association was age, pregnancy, and menopausal status dependent. These findings highlight the need to identify biological mechanisms contributing to sex specificity to facilitate risk stratification, targeted drug development, and improved management of long COVID.

A multi-omics approach to overeating and inactivity-induced muscle atrophy in db/db mice

BACKGROUND

Overeating and inactivity are associated with type 2 diabetes. This study aimed to investigate its pathological basis using integrated omics and db/db/mice, a model representing this condition.

METHODS

The study involved housing 8-week-old db/m and db/db mice for 8 weeks. Various analyses were conducted, including gene expression in skeletal muscle and small intestine using next-generation sequencing; cytokine arrays of serum; assessment of metabolites in skeletal muscle, stool, and serum; and analysis of the gut microbiota. Histone modifications in small intestinal epithelial cells were profiled using CUT&Tag.

RESULTS

Compared with db/m mice, db/db mice had 22.4% lower grip strength and approximately five times the visceral fat weight (P < 0.0001). Serum cytokine arrays showed a 2.8-fold relative concentration of VEGF-A in db/db mice (P < 0.0001) and lower concentrations of several other cytokines. mRNA sequencing revealed downregulation of Myh expression in skeletal muscle, upregulation of lipid and glucose transporters, and downregulation of amino acid transporters in the small intestine of db/db/mice. The concentrations of saturated fatty acids in skeletal muscle were significantly higher, and the levels of essential amino acids were lower in db/db mice. Analysis of the gut microbiota, 16S rRNA sequencing, revealed lower levels of the phylum Bacteroidetes (59.7% vs. 44.9%) and higher levels of the phylum Firmicutes (20.9% vs. 31.4%) in db/db mice (P = 0.003). The integrated signal of histone modifications of lipid and glucose transporters was higher, while the integrated signal of histone modifications of amino acid transporters was lower in the db/db mice.

CONCLUSIONS

The multi-omics approach provided insights into the epigenomic alterations in the small intestine, suggesting their involvement in the pathogenesis of inactivity-induced muscle atrophy in obese mice.

Epigenetic developmental mechanisms underlying sex differences in cancer

Cancer risk is modulated by hereditary and somatic mutations, exposures, age, sex, and gender. The mechanisms by which sex and gender work alone and in combination with other cancer risk factors remain underexplored. In general, cancers that occur in both the male and female sexes occur more commonly in XY compared with XX individuals, regardless of genetic ancestry, geographic location, and age. Moreover, XY individuals are less frequently cured of their cancers, highlighting the need for a greater understanding of sex and gender effects in oncology. This will be necessary for optimal laboratory and clinical cancer investigations. To that end, we review the epigenetics of sexual differentiation and its effect on cancer hallmark pathways throughout life. Specifically, we will touch on how sex differences in metabolism, immunity, pluripotency, and tumor suppressor functions are patterned through the epigenetic effects of imprinting, sex chromosome complement, X inactivation, genes escaping X inactivation, sex hormones, and life history.

RISING STARS: Androgens and immune cell function

Androgens can modulate immune cell function and may contribute to differences in the prevalence and severity of common inflammatory conditions. Although most immune cells are androgen targets, our understanding of how changes in androgen bioavailability can affect immune responses is incomplete. Androgens alter immune cell composition, phenotype, and activation by modulating the expression and secretion of inflammatory mediators or by altering the development and maturation of immune cell precursors. Androgens are generally associated with having suppressive effects on the immune system, but their impacts are cell and tissue context-dependent and can be highly nuanced even within immune cell subsets. In response to androgens, innate immune cells such as neutrophils, monocytes, and macrophages increase the production of the anti-inflammatory cytokine IL-10 and decrease nitric oxide production. Androgens promote the differentiation of T cell subsets and reduce the production of inflammatory mediators, such as IFNG, IL-4 and IL-5. Additionally, androgens/androgen receptor can promote the maturation of B cells. Thus, androgens can be considered as immunomodulatory agents, but further work is required to understand the precise molecular pathways that are regulated at the intersection between endocrine and inflammatory signals. This narrative review focusses on summarising our current understanding of how androgens can alter immune cell function and how this might affect inflammatory responses in health and disease.

Systemic immunological responses are dependent on sex and ovarian hormone presence following acute inhaled woodsmoke exposure

BACKGROUND

Rural regions of the western United States have experienced a noticeable surge in both the frequency and severity of acute wildfire events, which brings significant challenges to both public safety and environmental conservation efforts, with impacts felt globally. Identifying factors contributing to immune dysfunction, including endocrinological phenotypes, is essential to understanding how hormones may influence toxicological susceptibility.

METHODS

This exploratory study utilized male and female C57BL/6 mice as in vivo models to investigate distinct responses to acute woodsmoke (WS) exposure with a focus on sex-based differences. In a second set of investigations, two groups were established within the female mouse cohort. In one group, mice experienced ovariectomy (OVX) to simulate an ovarian hormone-deficient state similar to surgical menopause, while the other group received Sham surgery as controls, to investigate the mechanistic role of ovarian hormone presence in driving immune dysregulation following acute WS exposure. Each experimental cohort followed a consecutive 2-day protocol with daily 4-h exposure intervals under two conditions: control HEPA-filtered air (FA) and acute WS to simulate an acute wildfire episode.

RESULTS

Metals analysis of WS particulate matter (PM) revealed significantly increased levels of 63Cu, 182W, 208Pb, and 238U, compared to filtered air (FA) controls, providing insights into the specific metal components most impacted by the changing dynamics of wildfire occurrences in the region. Male and female mice exhibited diverse patterns in lung mRNA cytokine expression following WS exposure, with males showing downregulation and females displaying upregulation, notably for IL-1β, TNF-α, CXCL-1, CCL-5, TGF-β, and IL-6. After acute WS exposure, there were notable differences in the responses of macrophages, neutrophils, and bronchoalveolar lavage (BAL) cytokines IL-10, IL-6, IL-1β, and TNF-α. Significant diverse alterations were observed in BAL cytokines, specifically IL-1β, IL-10, IL-6, and TNF-α, as well as in the populations of immune cells, such as macrophages and polymorphonuclear leukocytes, in both Sham and OVX mice, following acute WS exposure. These findings elucidated the profound influence of hormonal changes on inflammatory outcomes, delineating substantial sex-related differences in immune activation and revealing altered immune responses in OVX mice due to ovarian hormone deficiency. In addition, the flow cytometry analysis highlighted the complex interaction between OVX surgery, acute WS exposure, and their collective impact on immune cell populations within the hematopoietic bone marrow niche.

CONCLUSIONS

In summary, both male and female mice, alongside females subjected to OVX and those who had sham surgery, exhibit significant variations in the expression of proinflammatory cytokines, chemokines, lung mRNA gene expression, and related functional networks linked to signaling pathways. These differences potentially act as mediators of sex-specific and hormonal influences in the systemic inflammatory response to acute WS exposure during a wildfire event. Understanding the regulatory roles of genes expressed differentially under environmental stressors holds considerable implications, aiding in identifying sex-specific therapeutic targets for addressing acute lung inflammation and injury.

An Evaluation of Type 1 Interferon Related Genes in Male and Female-Matched, SARS-CoV-2 Infected Individuals Early in the COVID-19 Pandemic

SARS-CoV-2 infection has claimed just over 1.1 million lives in the US since 2020. Globally, the SARS-CoV-2 respiratory infection spread to 771 million people and caused mortality in 6.9 million individuals to date. Much of the early literature showed that SARS-CoV-2 immunity was defective in the early stages of the pandemic, leading to heightened and, sometimes, chronic inflammatory responses in the lungs. This lung-associated 'cytokine storm' or 'cytokine release syndrome' led to the need for oxygen supplementation, respiratory distress syndrome, and mechanical ventilation in a relatively high number of people. In this study, we evaluated circulating PBMC from non-hospitalized, male and female, COVID-19+ individuals over the course of infection, from the day of diagnosis (day 0) to one-week post diagnosis (day 7), and finally 4 weeks after diagnosis (day 28). In our early studies, we included hospitalized and critically care patient PBMC; however, most of these individuals were lymphopenic, which limited our assessments of their immune integrity. We chose a panel of 30 interferon-stimulated genes (ISG) to evaluate by PCR and completed flow analysis for immune populations present in those PBMC. Lastly, we assessed immune activation by stimulating PBMC with common TLR ligands. We identified changes in innate cells, primarily the innate lymphoid cells (ILC, NK cells) and adaptive immune cells (CD4+ and CD8+ T cells) over this time course of infection. We found that the TLR-7 agonist, Resiquimod, and the TLR-4 ligand, LPS, induced significantly better IFNα and IFNγ responses in the later phase (day 28) of SARS-CoV-2 infection in those non-hospitalized COVID-19+ individuals as compared to early infection (day 0 and day 7). We concluded that TLR-7 and TLR-4 agonists may be effective adjuvants in COVID-19 vaccines for mounting immunity that is long-lasting against SARS-CoV-2 infection.

The Role of Biological Sex in Pre-Clinical (Mouse) mRNA Vaccine Studies

In this study, we consider the influence of biological sex-specific immune responses on the assessment of mRNA vaccines in pre-clinical murine studies. Recognising the established disparities in immune function attributed to genetic and hormonal differences between individuals of different biological sexes, we compared the mRNA expression and immune responses in mice of both biological sexes after intramuscular injection with mRNA incorporated within lipid nanoparticles. Regarding mRNA expression, no significant difference in protein (luciferase) expression at the injection site was observed between female and male mice following intramuscular administration; however, we found that female BALB/c mice exhibit significantly greater total IgG responses across the concentration range of mRNA lipid nanoparticles (LNPs) in comparison to their male counterparts. This study not only contributes to the scientific understanding of mRNA vaccine evaluation but also emphasizes the importance of considering biological sex in vaccine study designs during pre-clinical evaluation in murine studies.

Unique pathways downstream of TLR-4 and TLR-7 activation: sex-dependent behavioural, cytokine, and metabolic consequences

Introduction

Post-infection syndromes are characterised by fatigue, muscle pain, anhedonia, and cognitive impairment; mechanistic studies exploring these syndromes have focussed on pathways downstream of Toll-like receptor (TLR) 4 activation. Here, we investigated the mechanistic interplay between behaviour, metabolism, and inflammation downstream of TLR-7 activation compared to TLR-4 activation in male and female CD1 mice.

Methods

Animals received either a TLR-4 (LPS; 0.83 mg/kg) or TLR-7 (R848, 5 mg/kg) agonist, or saline, and behaviour was analysed in an Open Field (OF) at 24 h (n = 20/group). Plasma, liver, and prefrontal cortex (PFC) were collected for gene expression analysis at 24 h and 1H-NMR metabolomics.

Results

TLR-4 and TLR-7 activation decreased distance travelled and rearing in the OF, but activation of each receptor induced distinct cytokine responses and metabolome profiles. LPS increased IL-1β expression and CXCL1 in the PFC, but TLR7 activation did not and strongly induced PFC CXCL10 expression. Thus, TLR7 induced sickness behaviour is independent of IL-1β expression. In both cases, the behavioural response to TLR activation was sexually dimorphic: females were more resilient. However, dissociation was observed between the resilient female mice behaviour and the levels of gene cytokine expression, which was, in general, higher in the female mice. However, the metabolic shifts induced by immune activation were better correlated with the sex-dependent behavioural dimorphisms; increased levels of antioxidant potential in the female brain are intrinsic male/female metabolome differences. A common feature of both TLR4 and TLR7 activation was an increase in N-acetyl aspartate (NAA) in the PFC, which is likely be an allostatic response to the challenges as sickness behaviour is inversely correlated with NAA levels.

Discussion

The results highlight how the cytokine profile induced by one PAMP cannot be extrapolated to another, but they do reveal how the manipulation of the conserved metabolome response might afford a more generic approach to the treatment of post-infection syndromes.

Recovery from Respiratory Failure in Patients with Coronavirus Disease 2019

OBJECTIVE

Coronavirus disease 2019 (COVID-19) can cause hypoxic respiratory failure; long-term oxygen therapy (LTOT) duration is unknown.

MATERIAL AND METHODS

The aim was to investigate which patients would need LTOT after COVID-19 pneumonia. This single-center, prospective study was conducted at the Ankara University Faculty of Medicine, Department of Chest Diseases, between May 2021 and December 2021. The 70 patients hospitalized for COVID-19 pneumonia and discharged with LTOT due to hypoxemic respiratory failure were included. Patients were divided into 2 groups as group I (LTOT requirement <3 months) and group II (LTOT requirement continued ≥3 months).

RESULTS

The mean age was 64.4 ± 13.5 years, and 44 (62.9%) of them were male. The most frequently encountered comorbidities were cardiovascular disease (57.1%) and lung disease (22.9%). While PaO2 levels increased in both groups during the follow-up period, this increment was significantly higher in group I (PaO2: 66.6 ± 9.9 mm Hg, P < .001). The factors affecting the LTOT requirement were evaluated using binary logistic regression. On multivariate analyses of lymphocytes, ferritin, C-reactive protein, PaO2, SaO2, subpleural reticulation, and number of lobes affected (≥3 lobes), the SaO2 level and presence of subpleural reticulation were significantly different between the 2 groups [odds ratio (OR) (95% CI): 0.853 (0.749-0.971), P = .016] and [OR (95% CI): 0.171 (0.042-0.733), P = .017], respectively.

CONCLUSION

A significant proportion of patients who develop respiratory failure due to COVID-19 recover within the first 3 months. Factors determining the LTOT requirement for more than 3 months were SaO2 and the presence of subpleural reticulation.

Epigenetic regulation of Parkinson's disease risk variant GPNMB cg17274742 methylation by sex and exercise from Taiwan Biobank

Background

Parkinson's disease (PD) is a complex neurodegenerative disease with an elusive etiology that involves the interaction between genetic, behavioral, and environmental factors. Recently, epigenetic modifications, particularly DNA methylation, have been recognized to play an important role in the onset of PD. Glycoprotein non-metastatic melanoma protein B (GPNMB), a type I transmembrane protein crucial for immune cell activation and maturation, has emerged as a potential biomarker for the risk of PD. This research aims to investigate the influence of exercise and gender on the regulation of methylation levels of GPNMB cg17274742 in individuals.

Methods

We analyze data from 2,474 participants in the Taiwan Biobank, collected from 2008 and 2016. Methylation levels at the GPNMB cg17274742 CpG site were measured using Illumina Infinium MethylationEPIC beads. After excluding individuals with incomplete data or missing information on possible risk factors, our final analysis included 1,442 participants. We used multiple linear regression models to assess the association between sex and exercise with adjusted levels of GPNMB cg17274742 for age, BMI, smoking, drinking, coffee consumption, serum uric acid levels, and hypertension.

Results

Our results demonstrated that exercise significantly influenced the methylation levels of GPNMB cg17274742 in males (β = -0.00242; p = 0.0026), but not in females (β = -0.00002362; p = 0.9785). Furthermore, male participants who exercised showed significantly lower levels of methylation compared to the reference groups of the female and non-exercising reference groups (β = -0.00357; p = 0.0079). The effect of the interaction between gender and exercise on the methylation of GPNMB cg17274742 was statistically significant (p = 0.0078).

Conclusion

This study suggests that gender and exercise can modulate GPNMB cg17274742, with hypomethylation observed in exercise men. More research is needed to understand the underlying mechanisms and implications of these epigenetic changes in the context of risk and prevention strategies.

Menstrual disturbances following COVID-19 vaccination: A probable puzzle about the role of endocrine and immune pathways

Menstruation is a monthly shedding of the uterine wall, presented by menstrual bleeding in women of reproductive age. Menstruation is regulated by fluctuation of estrogen and progesterone, as well as other endocrine and immune pathways. Many women experienced menstrual disturbances after vaccination against the novel coronavirus in the last two years. Vaccine-induced menstrual disturbances have led to discomfort and concern among reproductive-age women, such that some decided not to receive the subsequent doses of the vaccine. Although many vaccinated women report these menstrual disturbances, the mechanism is still poorly understood. This review article discusses the endocrine and immune changes following COVID-19 vaccination and the possible mechanisms of vaccine-related menstrual disturbances.

Pregnancy-induced differential expression of SARS-CoV-2 and influenza a viral entry factors in the lower respiratory tract

Despite differences in the clinical presentation of coronavirus disease-19 and pandemic influenza in pregnancy, fundamental mechanistic insights are currently lacking because of the difficulty in recruiting critically ill pregnant subjects for research studies. Therefore, to better understand host-pathogen interaction during pregnancy, we performed a series of foundational experiments in pregnant rats at term gestation to assess the expression of host entry factors for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza A virus (IAV) and genes associated with innate immune response in the lower respiratory tract. We report that pregnancy is characterized by a decrease in host factors mediating SARS-CoV-2 entry and an increase in host factors mediating IAV entry. Furthermore, using flow cytometric assessment of immune cell populations and immune provocation studies, we show an increased prevalence of plasmacytoid dendritic cells and a Type I interferon-biased environment in the lower respiratory tract of pregnancy, contrary to the expected immunological indolence. Our findings, therefore, suggest that the dissimilar clinical presentation of COVID-19 and pandemic influenza A in pregnancy could partly be due to differences in the extent of innate immune activation from altered viral tropism and indicate the need for comparative mechanistic investigations with live virus studies.

Variation in mouse chemical signals is genetically controlled and environmentally modulated

In most mammals and particularly in mice, chemical communication relies on the detection of ethologically relevant fitness-related cues from other individuals. In mice, urine is the primary source of these signals, so we employed proteomics and metabolomics to identify key components of chemical signalling. We show that there is a correspondence between urinary volatiles and proteins in the representation of genetic background, sex and environment in two house mouse subspecies Mus musculus musculus and M. m. domesticus. We found that environment has a strong influence upon proteomic and metabolomic variation and that volatile mixtures better represent males while females have surprisingly more sex-biased proteins. Using machine learning and combined-omics techniques, we identified mixtures of metabolites and proteins that are associated with biological features.

Acute upper respiratory infections admissions in England and Wales

Acute respiratory infections block the bronchial and/or nasal systems' airways. These infections may present in a variety of ways, from minor symptoms like the common cold to more serious illnesses like pneumonia or lung collapse. Acute respiratory infections cause over 1.3 million infant deaths under the age of 5 each year throughout the world. Among all illnesses, respiratory infections make for 6% of the worldwide disease burden. We aimed to examine the admissions related to acute upper respiratory infections admissions in England and Wales for the period between April 1999 and April 2020. This was an ecological study using publicly available data extracted from the Hospital Episode Statistics database in England, and the Patient Episode Database for Wales for the period between April 1999 and April 2020. The acute upper respiratory infections-related hospital admissions were identified using the Tenth Revision of the International Statistical Classification of Diseases and Related Health Problems 5th Edition (used by National Health Service [NHS] to classify diseases and other health conditions) (J00-J06). The total annual number of admissions for various reasons increased by 1.09-fold (from 92,442 in 1999 to 193,236 in 2020), expressing an increase in hospital admission rate of 82.5% (from 177.30 [95% confidence interval {CI}: 176.15-178.44] in 1999 to 323.57 [95%CI: 322.13-325.01] in 2020 per 100,000 persons, P < .01). The most common causes were acute tonsillitis and acute upper respiratory infections of multiple and unspecified sites, which accounted for 43.1% and 39.4%, respectively. Hospital admissions rate due to acute upper respiratory infections increased sharply during the study period. The rates of hospital admissions were higher among those in the age group below 15 and 75 years and above for the majority of respiratory infections, with a higher incidence in females.

Melatonin and Cytokines Modulate Daily Instrumental Activities of Elderly People with SARS-CoV-2 Infection

The Comprehensive Geriatric Assessment analyzes the health and quality of life of the elderly. Basic and instrumental daily activities may be compromised due to neuroimmunoendocrine changes, and studies suggest that possible immunological changes occur during infections in the elderly. Thus, this study aimed to analyze cytokine and melatonin levels in serum and correlate the Comprehensive Geriatric Assessment in elderly patients with SARS-CoV-2 infection. The sample consisted of 73 elderly individuals, 43 of whom were without infection and 30 of whom had positive diagnoses of COVID-19. Blood samples were collected to quantify cytokines by flow cytometry and melatonin by ELISA. In addition, structured and validated questionnaires were applied to assess basic (Katz) and instrumental (Lawton and Brody) activities. There was an increase in IL-6, IL-17, and melatonin in the group of elderly individuals with infection. In addition, a positive correlation was observed between melatonin and IL-6 and IL-17 in elderly patients with SARS-CoV-2 infection. Furthermore, there was a reduction in the score of the Lawton and Brody Scale in the infected elderly. These data suggest that the melatonin hormone and inflammatory cytokines are altered in the serum of the elderly with SARS-CoV-2 infection. In addition, there is a degree of dependence, mainly regarding the performance of daily instrumental activities, in the elderly. The considerable impact on the elderly person's ability to perform everyday tasks necessary for independent living is an extremely important result, and changes in cytokines and melatonin probably are associated with alterations in these daily activities of the elderly.

Sex hormones in SARS-CoV-2 susceptibility: key players or confounders?

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has a clear sex disparity in clinical outcomes. Hence, the interaction between sex hormones, virus entry receptors and immune responses has attracted major interest as a target for the prevention and treatment of SARS-CoV-2 infections. This Review summarizes the current understanding of the roles of androgens, oestrogens and progesterone in the regulation of virus entry receptors and disease progression of coronavirus disease 2019 (COVID-19) as well as their therapeutic value. Although many experimental and clinical studies have analysed potential mechanisms by which female sex hormones might provide protection against SARS-CoV-2 infectivity, there is currently no clear evidence for a sex-specific expression of virus entry receptors. In addition, reports describing an influence of oestrogen, progesterone and androgens on the course of COVID-19 vary widely. Current data also do not support the administration of oestradiol in COVID-19. The conflicting evidence and lack of consensus results from a paucity of mechanistic studies and clinical trials reporting sex-disaggregated data. Further, the influence of variables beyond biological factors (sex), such as sociocultural factors (gender), on COVID-19 manifestations has not been investigated. Future research will have to fill this knowledge gap as the influence of sex and gender on COVID-19 will be essential to understanding and managing the long-term consequences of this pandemic.

Sex chromosome complement and sex steroid signaling underlie sex differences in immunity to respiratory virus infection

Epidemiological studies have revealed sex differences in the incidence and morbidity of respiratory virus infection in the human population, and often these observations are correlated with sex differences in the quality or magnitude of the immune response. Sex differences in immunity and morbidity also are observed in animal models of respiratory virus infection, suggesting differential dominance of specific immune mechanisms. Emerging research shows intrinsic sex differences in immune cell transcriptomes, epigenomes, and proteomes that may regulate human immunity when challenged by viral infection. Here, we highlight recent research into the role(s) of sex steroids and X chromosome complement in immune cells and describe how these findings provide insight into immunity during respiratory virus infection. We focus on the regulation of innate and adaptive immune cells by receptors for androgen and estrogens, as well as genes with a propensity to escape X chromosome inactivation. A deeper mechanistic knowledge of these pathways will help us to understand the often significant sex differences in immunity to endemic or pandemic respiratory pathogens such as influenza viruses, respiratory syncytial viruses and pathogenic coronaviruses.

Vitamin D and estrogen steroid hormones and their immunogenetic roles in Infectious respiratory (TB and COVID-19) diseases

The role of steroid hormones against infectious diseases has been extensively studied. From immunomodulatory action to direct inhibition of microorganism growth, hormones D3 (VD3) and 17β-estradiol (E2), and the genetic pathways modulated by them, are key targets for a better understanding pathogenesis of infectious respiratory diseases (IRD) such as tuberculosis (TB) and the coronavirus disease-19 (COVID-19). Currently, the world faces two major public health problems, the outbreak of COVID-19, accounting for more than 6 million so far, and TB, more than 1 million deaths per year. Both, although resulting from different pathogens, the Mtb and the SARS-CoV-2, respectively, are considered serious and epidemic. TB and COVID-19 present similar infection rates between men and women, however the number of complications and deaths resulting from the two infections is higher in men when compared to women in childbearing age, which may indicate a role of the sex hormone E2 in the context of these diseases. E2 and VD3 act upon key gene pathways as important immunomodulatory players and supporting molecules in IRDs. This review summarizes the main roles of these hormones (VD3 and E2) in modulating immune and inflammatory responses and their relationship with TB and COVID-19.

Low-Dose Sodium Salicylate Promotes Ovulation by Regulating Steroids via CYP17A1

To meet the current demand of assisted reproduction and animal breeding via superovulation and reduce the impact of hormone drugs, it is necessary to develop new superovulation drugs. This study examined the role of inflammation and steroids in ovulation. Sodium salicylate can regulate inflammation and steroids. However, the effect of sodium salicylate on ovulation has not been studied. In this study, mice were intraperitoneally injected with different concentrations of sodium salicylate for four consecutive days. The effects of sodium salicylate on oocyte quality and on the number of ovulations were examined, and these effects were compared with those of pregnant horse serum gonadotropin (PMSG)/follicle-stimulating hormone (FSH) treatment. We found that low-dose sodium salicylate increased the levels of ovulation hormones and inflammation by promoting the expression of CYP17A1. Sodium salicylate had the same effect as the commonly used superovulation drug PMSG/FSH and reduced the histone methylation level. Sodium salicylate can promote ovulation in mice and Awang sheep. It can greatly decrease the use of hormone drugs, reduce breeding costs and physical impacts, and can thus be used for livestock breeding.

Risk Factors of Severe COVID-19: A Review of Host, Viral and Environmental Factors

The clinical course and outcome of COVID-19 are highly variable, ranging from asymptomatic infections to severe disease and death. Understanding the risk factors of severe COVID-19 is relevant both in the clinical setting and at the epidemiological level. Here, we provide an overview of host, viral and environmental factors that have been shown or (in some cases) hypothesized to be associated with severe clinical outcomes. The factors considered in detail include the age and frailty, genetic polymorphisms, biological sex (and pregnancy), co- and superinfections, non-communicable comorbidities, immunological history, microbiota, and lifestyle of the patient; viral genetic variation and infecting dose; socioeconomic factors; and air pollution. For each category, we compile (sometimes conflicting) evidence for the association of the factor with COVID-19 outcomes (including the strength of the effect) and outline possible action mechanisms. We also discuss the complex interactions between the various risk factors.

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.

A population-based cohort study of sex and risk of severe outcomes in covid-19

There is a male sex disadvantage in morbidity and mortality due to COVID-19. Proposed explanations to this disparity include gender-related health behaviors, differential distribution of comorbidities and biological sex differences. In this study, we investigated the association between sex and risk of severe COVID-19 while adjusting for comorbidities, socioeconomic factors, as well as unmeasured factors shared by cohabitants which are often left unadjusted. We conducted a total-population-based cohort study (n = 1,854,661) based on individual-level register data. Cox models was used to estimate the associations between sex and risk for severe COVID-19. We additionally used a within-household design and conditional Cox models aiming to account for unmeasured factors shared by cohabitants. A secondary aim was to compare the risk of COVID-19 related secondary outcomes between men and women hospitalized due to COVID-19 using logistic regression. Men were at higher risk for hospitalization (HR = 1.63;95%CI = 1.57–1.68), ICU admission (HR = 2.63;95%CI = 2.38–2.91) and death (HR = 1.81;95%CI = 1.68–1.95) due to COVID-19, based on fully adjusted models. However, the effect of sex varied significantly across age groups: Among people in their 50s, men had > four times higher risk of COVID-19 death. The within-household design did not provide any further explanation to the sex disparity. Among patients hospitalized due to COVID-19, men had an increased risk for viral pneumonia, acute respiratory distress syndrome, acute respiratory insufficiency, acute kidney injury, and sepsis which persisted in fully adjusted models. Recognition of the combined effect of sex and age on COVID-19 outcomes has implications for policy strategies to reduce the adverse effects of the disease.

Testosterone induces sexual dimorphism during infection with Plasmodium berghei ANKA

Malaria is the most lethal parasitic disease worldwide; men exhibit higher mortality and more severe symptomatology than women; however, in most studies of immune response in malaria, sex is not considered a variable. Sex hormones 17β-oestradiol and testosterone are responsible for the main physiological differences between sexes. When interacting with their receptors on different immune cells, they modify the expression of genes that modulate cell proliferation, differentiation, and synthesis of cytokines. The immunosuppressive activity of testosterone is well accepted; however, its participation in the sexual dimorphism of the immune response to malaria has not been studied. In this work, we analysed whether altering the concentration of testosterone, through increasing the concentration of this hormone for exogenous administration for three weeks, or gonadectomy before infection with Plasmodium berghei ANKA affects different cells of the immune response necessary for parasite clearance. We also assessed the concentration of pro-and anti-inflammatory cytokines in male and female CBA/Ca mice infected or not with the parasite. Our results show that testosterone changes affect females more than males, resulting in sex-associated patterns. Testosterone administration increased parasitaemia in intact males while reducing it in intact females leading to a dimorphic pattern. In addition, gonadectomy increased parasitaemia in both sexes. Moreover, testosterone administration prevented both weight loss caused by the infection in females and hypothermia in gonadectomized mice of both sexes. Boosting testosterone concentration increased CD3+ and CD8+ populations but decreased the B220+ cells exclusively in females. Additionally, testosterone reduced IFN-γ concentration and increased IL-6 levels only in females, while in males, testosterone increased the number of NK cells. Finally, gonadectomy decreased TNF-α concentration in both sexes. Our results demonstrate that testosterone induces different patterns depending on sex and testosterone concentration. The results of this work contribute to understanding the impact of modifying testosterone concentration on the immune response specific against Plasmodium and the participation of this hormone in sexual dimorphism in malaria.

Correlation between Type I Interferon Associated Factors and COVID-19 Severity

Antiviral type I interferons (IFN) produced in the early phase of viral infections effectively inhibit viral replication, prevent virus-mediated tissue damages and promote innate and adaptive immune responses that are all essential to the successful elimination of viruses. As professional type I IFN producing cells, plasmacytoid dendritic cells (pDC) have the ability to rapidly produce waste amounts of type I IFNs. Therefore, their low frequency, dysfunction or decreased capacity to produce type I IFNs might increase the risk of severe viral infections. In accordance with that, declined pDC numbers and delayed or inadequate type I IFN responses could be observed in patients with severe coronavirus disease (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), as compared to individuals with mild or no symptoms. Thus, besides chronic diseases, all those conditions, which negatively affect the antiviral IFN responses lengthen the list of risk factors for severe COVID-19. In the current review, we would like to briefly discuss the role and dysregulation of pDC/type I IFN axis in COVID-19, and introduce those type I IFN-dependent factors, which account for an increased risk of COVID-19 severity and thus are responsible for the different magnitude of individual immune responses to SARS-CoV-2.

Progesterone as an Anti-Inflammatory Drug and Immunomodulator: New Aspects in Hormonal Regulation of the Inflammation

The specific regulation of inflammatory processes by steroid hormones has been actively studied in recent years, especially by progesterone (P₄) and progestins. The mechanisms of the anti-inflammatory and immunomodulatory P₄ action are not fully clear. The anti-inflammatory effects of P₄ can be defined as nonspecific, associated with the inhibition of NF-κB and COX, as well as the inhibition of prostaglandin synthesis, or as specific, associated with the regulation of T-cell activation, the regulation of the production of pro- and anti-inflammatory cytokines, and the phenomenon of immune tolerance. The specific anti-inflammatory effects of P₄ and its derivatives (progestins) can also include the inhibition of proliferative signaling pathways and the antagonistic action against estrogen receptor beta-mediated signaling as a proinflammatory and mitogenic factor. The anti-inflammatory action of P₄ is accomplished through the participation of progesterone receptor (PR) chaperones HSP90, as well as immunophilins FKBP51 and FKBP52, which are the validated targets of clinically approved immunosuppressive drugs. The immunomodulatory and anti-inflammatory effects of HSP90 inhibitors, tacrolimus and cyclosporine, are manifested, among other factors, due to their participation in the formation of an active ligand–receptor complex of P₄ and their interaction with its constituent immunophilins. Pharmacological agents such as HSP90 inhibitors can restore the lost anti-inflammatory effect of glucocorticoids and P₄ in chronic inflammatory and autoimmune diseases. By regulating the activity of FKBP51 and FKBP52, it is possible to increase or decrease hormonal signaling, as well as restore it during the development of hormone resistance. The combined action of immunophilin suppressors with steroid hormones may be a promising strategy in the treatment of chronic inflammatory and autoimmune diseases, including endometriosis, stress-related disorders, rheumatoid arthritis, and miscarriages. Presumably, the hormone receptor- and immunophilin-targeted drugs may act synergistically, allowing for a lower dose of each.

Female offspring gestated in hypothyroxinemia and infected with human Metapneumovirus (hMPV) suffer a more severe infection and have a higher number of activated CD8+ T lymphocytes

Maternal thyroid hormones (THs) are essential for the appropriate development of the fetus and especially for the brain. Recently, some studies have shown that THs deficiency can also alter the immune system development of the progeny and their ability to mount an appropriate response against infectious agents. In this study, we evaluated whether adult mice gestated under hypothyroxinemia (Hpx) showed an altered immune response against infection with human metapneumovirus (hMPV). We observed that female mice gestated under Hpx showed higher clinical scores after seven days of hMPV infection. Besides, males gestated under Hpx have higher lung viral loads at day seven post-infection. Furthermore, the female offspring gestated in Hpx have already reduced the viral load at day seven and accordingly showed an increased proportion of activated (CD71⁺ and FasL⁺) CD8⁺ T cells in the lungs, which correlated with a trend for a higher histopathological clinical score. These results support that T₄ deficiency during gestation might condition the offspring differently in males and females, enhancing their ability to respond to hMPV.

A sesquiterpene isolated from the stems and leaves of Dioscorea opposita thunb. Transforms the composition of immune cells through ERβ in a mouse model of LPS-induced lung injury

Acute lung injury (ALI) is a common critical disease with a high mortality rate. Natural products have marked efficacy in the prevention and treatment of ALI, in addition, estrogen and its receptors are involved in the pathogenesis and development of lung injury. Our previous research shows that sesquiterpenes isolated from the stems and leaves of Dioscorea opposita Thunb. have anti-inflammatory and estrogenic-like activity. In the present study, sesquiterpene (A1) is a natural extract from the stems and leaves of Dioscorea opposita Thunb. with a view to determining whether A1 can improve lung function in a mouse model of LPS-induced ALI and exploring the involvement of the estrogen receptor β (ERβ) pathway. A1 (20 or 40 mg/kg, i. g., 2 times/day) was administered for 3 d, followed by the induction of ALI via an intratracheal LPS drip (5 mg/kg/2 h). The lung function and levels of inflammation, immune cells, apoptosis, and ERβ expression were examined. The antagonistic activity of specific ERβ blocker (THC, 1 μM) against A1 (20 μM) in co-cultured BEAS-2B cells and splenic lymphocytes induced with LPS (1 μg/mL, 24 h) was also investigated to assess whether the observed effects of A1 were mediated by ERβ. A1 improved lung function, regulated the immune system, and decreased inflammation and apoptosis. Moreover, A1 increased the expression of ERβ in LPS-induced mice, and antagonism of ERβ decreased the protective effects of A1 in a co-culture system. A1 had anti-ALI effects that might partially mediated through ERβ signaling. Our data provide molecular justification for the use of A1 in the treatment of ALI.

17β-Oestradiol Protects from Hepatitis C Virus Infection through Induction of Type I Interferon

Background and Aims: Sex hormones are widely recognised to act as protective factors against several viral infections. Specifically, females infected by the hepatitis C virus display higher clearance rates and reduced disease progression than those found in males. Through modulation of particle release and spread, 17β-oestradiol controls HCV’s life cycle. We investigated the mechanism(s) behind oestrogen’s antiviral effect. Methods: We used cell culture-derived hepatitis C virus in in vitro assays to evaluate the effect of 17β-oestradiol on the innate immune response. Host immune responses were evaluated by enumerating gene transcripts via RT-qPCR in cells exposed to oestrogen in the presence or absence of viral infection. Antiviral effects were determined by focus-forming unit assay or HCV RNA quantification. Results: Stimulation of 17β-oestradiol triggers a pre-activated antiviral state in hepatocytes, which can be maintained for several hours after the hormone is removed. This induction results in the elevation of several innate immune genes, such as interferon alpha and beta, tumour necrosis factor, toll-like receptor 3 and interferon regulatory factor 5. We demonstrated that this pre-activation of immune response signalling is not affected by a viral presence, and the antiviral state can be ablated using an interferon-alpha/beta receptor alpha inhibitor. Finally, we proved that the oestrogen-induced stimulation is essential to generate an antiviral microenvironment mediated by activation of type I interferons. Conclusion: Resulting in viral control and suppression, 17β-oestradiol induces an interferon-mediated antiviral state in hepatocytes. Oestrogen-stimulated cells modulate the immune response through secretion of type I interferon, which can be countered by blocking interferon-alpha/beta receptor alpha signalling.

Sex hormones and immune system: Menopausal hormone therapy in the context of COVID-19 pandemic

The fatal outcomes of COVID-19 are related to the high reactivity of the innate wing of immunity. Estrogens could exert anti-inflammatory effects during SARS-CoV-2 infection at different stages: from increasing the antiviral resistance of individual cells to counteracting the pro-inflammatory cytokine production. A complex relationship between sex hormones and immune system implies that menopausal hormone therapy (MHT) has pleiotropic effects on immunity in peri- and postmenopausal patients. The definite immunological benefits of perimenopausal MHT confirm the important role of estrogens in regulation of immune functionalities. In this review, we attempt to explore how sex hormones and MHT affect immunological parameters of the organism at different level (in vitro, in vivo) and what mechanisms are involved in their protective response to the new coronavirus infection. The correlation of sex steroid levels with severity and lethality of the disease indicates the potential of using hormone therapy to modulate the immune response and increase the resilience to adverse outcomes. The overall success of MHT is based on decades of experience in clinical trials. According to the current standards, MHT should not be discontinued in COVID-19 with the exception of critical cases.

Pandemics, past and present: The role of biological anthropology in interdisciplinary pandemic studies

Biological anthropologists are ideally suited for the study of pandemics given their strengths in human biology, health, culture, and behavior, yet pandemics have historically not been a major focus of research. The COVID‐19 pandemic has reinforced the need to understand pandemic causes and unequal consequences at multiple levels. Insights from past pandemics can strengthen the knowledge base and inform the study of current and future pandemics through an anthropological lens. In this paper, we discuss the distinctive social and epidemiological features of pandemics, as well as the ways in which biological anthropologists have previously studied infectious diseases, epidemics, and pandemics. We then review interdisciplinary research on three pandemics–1918 influenza, 2009 influenza, and COVID‐19–focusing on persistent social inequalities in morbidity and mortality related to sex and gender; race, ethnicity, and Indigeneity; and pre‐existing health and disability. Following this review of the current state of pandemic research on these topics, we conclude with a discussion of ways biological anthropologists can contribute to this field moving forward. Biological anthropologists can add rich historical and cross‐cultural depth to the study of pandemics, provide insights into the biosocial complexities of pandemics using the theory of syndemics, investigate the social and health impacts of stress and stigma, and address important methodological and ethical issues. As COVID‐19 is unlikely to be the last global pandemic, stronger involvement of biological anthropology in pandemic studies and public health policy and research is vital.

Sex Steroids Effects on Asthma: A Network Perspective of Immune and Airway Cells

A multitude of evidence has suggested the differential incidence, prevalence and severity of asthma between males and females. A compilation of recent literature recognized sex differences as a significant non-modifiable risk factor in asthma pathogenesis. Understanding the cellular and mechanistic basis of sex differences remains complex and the pivotal point of this ever elusive quest, which remains to be clarified in the current scenario. Sex steroids are an integral part of human development and evolution while also playing a critical role in the conditioning of the immune system and thereby influencing the function of peripheral organs. Classical perspectives suggest a pre-defined effect of sex steroids, generalizing estrogens popularly under the “estrogen paradox” due to conflicting reports associating estrogen with a pro- and anti-inflammatory role. On the other hand, androgens are classified as “anti-inflammatory,” serving a protective role in mitigating inflammation. Although considered mainstream and simplistic, this observation remains valid for numerous reasons, as elaborated in the current review. Women appear immune-favored with stronger and more responsive immune elements than men. However, the remarkable female predominance of diverse autoimmune and allergic diseases contradicts this observation suggesting that hormonal differences between the sexes might modulate the normal and dysfunctional regulation of the immune system. This review illustrates the potential relationship between key elements of the immune cell system and their interplay with sex steroids, relevant to structural cells in the pathophysiology of asthma and many other lung diseases. Here, we discuss established and emerging paradigms in the clarification of observed sex differences in asthma in the context of the immune system, which will deepen our understanding of asthma etiopathology.

The Hepatoprotective and Hepatotoxic Roles of Sex and Sex-Related Hormones

Most liver diseases, including acute liver injury, drug-induced liver injury, viral hepatitis, metabolic liver diseases, and end-stage liver diseases, are strongly linked with hormonal influences. Thus, delineating the clinical manifestation and underlying mechanisms of the “sexual dimorphism” is critical for providing hints for the prevention, management, and treatment of those diseases. Whether the sex hormones (androgen, estrogen, and progesterone) and sex-related hormones (gonadotrophin-releasing hormone, luteinizing hormone, follicle-stimulating hormone, and prolactin) play protective or toxic roles in the liver depends on the biological sex, disease stage, precipitating factor, and even the psychiatric status. Lifestyle factors, such as obesity, alcohol drinking, and smoking, also drastically affect the involving mechanisms of those hormones in liver diseases. Hormones deliver their hepatic regulatory signals primarily via classical and non-classical receptors in different liver cell types. Exogenous sex/sex-related hormone therapy may serve as a novel strategy for metabolic liver disease, cirrhosis, and liver cancer. However, the undesired hormone-induced liver injury should be carefully studied in pre-clinical models and monitored in clinical applications. This issue is particularly important for menopause females with hormone replacement therapy (HRT) and transgender populations who want to receive gender-affirming hormone therapy (GAHT). In conclusion, basic and clinical studies are warranted to depict the detailed hepatoprotective and hepatotoxic mechanisms of sex/sex-related hormones in liver disease. Prolactin holds a promising perspective in treating metabolic and advanced liver diseases.

The influence of age and sex in sarcoidosis

PURPOSE OF REVIEW

This review aims to describe how the clinical manifestations of sarcoidosis may be shaped by the effects of sex hormones and by age dependent changes in immune functions and physiology This review is intended to highlight the need to consider the effects of sex and sex in future studies of sarcoidosis.

RECENT FINDINGS

The clinical manifestations of sarcoidosis differ based on sex and gender There is emerging evidence that female and male hormones and X-linked genes are important determinants of immune responses to environmental antigens, which has important implications for granuloma formation in the context of sarcoidosis Furthermore, sex hormone levels predictably change throughout adolescence and adulthood, and this occurs in parallel with the onset immune senescence and changes in physiology with advanced age.

SUMMARY

Recent studies indicate that sex and age are important variables shaping the immune response of humans to environmental antigens We posit herein that sex and age are important determinants of sarcoidosis clinical phenotypes Many gaps in our understanding of the roles played by sex and gender in sarcoidosis, and these need to be considered in future studies.

Epigenetic mechanisms regulate sex-specific bias in disease manifestations

Abstract

Sex presents a vital determinant of a person’s physiology, anatomy, and development. Recent clinical studies indicate that sex is also involved in the differential manifestation of various diseases, affecting both clinical outcome as well as response to therapy. Genetic and epigenetic changes are implicated in sex bias and regulate disease onset, including the inactivation of the X chromosome as well as sex chromosome aneuploidy. The differential expression of X-linked genes, along with the presence of sex-specific hormones, exhibits a significant impact on immune system function. Several studies have revealed differences between the two sexes in response to infections, including respiratory diseases and COVID-19 infection, autoimmune disorders, liver fibrosis, neuropsychiatric diseases, and cancer susceptibility, which can be explained by sex-biased immune responses. In the present review, we explore the input of genetic and epigenetic interplay in the sex bias underlying disease manifestation and discuss their effects along with sex hormones on disease development and progression, aiming to reveal potential new therapeutic targets.

Key messages

Sex is involved in the differential manifestation of various diseases.

Epigenetic modifications influence X-linked gene expression, affecting immune response to infections, including COVID-19.

Epigenetic mechanisms are responsible for the sex bias observed in several respiratory and autoimmune disorders, liver fibrosis, neuropsychiatric diseases, and cancer.

Sex-Biased Control of Inflammation and Metabolism by a Mitochondrial Nod-Like Receptor

Mitochondria regulate steroid hormone synthesis, and in turn sex hormones regulate mitochondrial function for maintaining cellular homeostasis and controlling inflammation. This crosstalk can explain sex differences observed in several pathologies such as in metabolic or inflammatory disorders. Nod-like receptor X1 (NLRX1) is a mitochondria-associated innate receptor that could modulate metabolic functions and attenuates inflammatory responses. Here, we showed that in an infectious model with the human protozoan parasite, Leishmania guyanensis, NLRX1 attenuated inflammation in females but not in male mice. Analysis of infected female and male bone marrow derived macrophages showed both sex- and genotype-specific differences in both inflammatory and metabolic profiles with increased type I interferon production, mitochondrial respiration, and glycolytic rate in Nlrx1-deficient female BMDMs in comparison to wild-type cells, while no differences were observed between males. Transcriptomics of female and male BMDMs revealed an altered steroid hormone signaling in Nlrx1-deficient cells, and a “masculinization” of Nlrx1-deficient female BMDMs. Thus, our findings suggest that NLRX1 prevents uncontrolled inflammation and metabolism in females and therefore may contribute to the sex differences observed in infectious and inflammatory diseases.

Biological sex: an understudied factor driving disease susceptibility in pigs

Biological sex is a major host factor influencing risk for infectious disease-associated mortality, and chronic inflammatory and metabolic diseases. Research in human and rodent models -has revealed sex differences that exist across organ systems during health and disease that may contribute to sex biases in disease risk. Despite the robust and growing literature on the role of sex as a risk factor in human disease, comparatively little attention has been focused on investigating the role of biological sex in disease susceptibility in agriculturally important animal populations such as the pig. To date, comparisons between sexes have focused on carcass composition, growth rate, and feed efficiency in pigs. However, there is a large gap in the literature regarding the effects of biological sex on other integral aspects of health and disease. The objective of this review is to highlight the available literature reporting sex differences in pig health and biology with an emphasis on sex differences in mortality, immunity, and gastrointestinal (GI) physiology and to address biological sex as a significant biological variable in disease risk and research study design. A basic overview of the biology of sex differences including the major hormonal and genetic/chromosomal mechanisms of sexual differentiation and the developmental periods in which sex differences emerge will be covered. This review will also discuss how production-relevant management and environmental factors (e.g., wean age, castration, stress, and nutrition) interact with biological sex to shape host immune and GI development and function. Perceived gaps in knowledge and areas of future research will also be discussed.

Immunological Changes in Pregnancy and Prospects of Therapeutic Pla-Xosomes in Adverse Pregnancy Outcomes

Stringent balance of the immune system is a key regulatory factor in defining successful implantation, fetal development, and timely parturition. Interference in these primary regulatory mechanisms, either at adolescence or prenatal state led to adverse pregnancy outcomes. Fertility restoration with the help of injectable gonadotrophins/progesterone, ovulation-inducing drugs, immunomodulatory drugs (corticosteroids), and reproductive surgeries provides inadequate responses, which manifest its own side effects. The development of a potential diagnostic biomarker and an effectual treatment for adverse pregnancy outcomes is a prerequisite to maternal and child health. Parent cell originated bi-layered-intraluminal nano-vesicles (30-150 nm) also known as exosomes are detected in all types of bodily fluids like blood, saliva, breast milk, urine, etc. Exosomes being the most biological residual structures with the least cytotoxicity are loaded with cargo in the form of RNAs (miRNAs), proteins (cytokines), hormones (estrogen, progesterone, etc.), cDNAs, and metabolites making them chief molecules of cell-cell communication. Their keen involvement in the regulation of biological processes has portrayed them as the power shots of cues to understand the disease's pathophysiology and progression. Recent studies have demonstrated the role of immunexosomes (immunomodulating exosomes) in maintaining unwavering immune homeostasis between the mother and developing fetus for a healthy pregnancy. Moreover, the concentration and size of the exosomes are extensively studied in adverse pregnancies like preeclampsia, gestational diabetes mellitus (GDM), and preterm premature rupture of membrane (pPROMs) as an early diagnostic marker, thus giving in-depth information about their pathophysiology. Exosomes have also been engineered physically as well as genetically to enhance their encapsulation efficiency and specificity in therapy for cancer and adverse pregnancies. Successful bench to bedside discoveries and interventions in cancer has motivated developmental biologists to investigate the role of immunexosomes and their active components. Our review summarizes the pre-clinical studies for the use of these power-shots as therapeutic agents. We envisage that these studies will pave the path for the use of immunexosomes in clinical settings for reproductive problems that arise due to immune perturbance in homeostasis either at adolescence or prenatal state.

Estradiol Aggravate Nocardia farcinica Infections in Mice

Males are generally more susceptible to Nocardia infection than females, with a male-to-female ratio of 2 and higher clinical disease. 17β-Estradiol has been implicated in affecting the sex-based gap by inhibiting the growth of N. brasiliensis in experiments, but the underlying mechanisms have not yet been fully clarified. In the present study, however, we report increased severity in N. farcinica IFM 10152-infected female mice compared with male mice with increased mortality, elevated lung bacterial loads and an exaggerated pulmonary inflammatory response, which was mimicked in ovariectomized female mice supplemented with E2. Similarly, the overwhelming increase in bacterial loads was also evident in E2-treated host cells, which were associated with downregulating the phosphorylation level of the MAPK pathway by binding the estrogen receptor. We conclude that although there are more clinical cases of Nocardia infection in males, estrogen promotes the survival of the bacteria, which leads to aggravated inflammation in females. Our data emphasize the need to include and separately analyze both sexes in future studies of Nocardia to understand the sex differences in immune responses and disease pathogenesis.

Hiding in Plain Sight: Factors Influencing the Neuroinflammatory Response to Sport-Related Concussion

Sport-related concussion (SRC) is a major concern among athletes and clinicians around the world. Research into fluid biomarkers of SRC has made significant progress in understanding the complex underlying pathophysiology of concussion. However, little headway has been made toward clinically validating any biomarkers to improve the clinical management of SRC. A major obstacle toward clinical translation of any fluid biomarker is the heterogeneity of SRC overlapping with multiple physiological systems involved in pathology and recovery. Neuroinflammation post-SRC is one such system that may confound fluid biomarker data on many fronts. Neuroinflammatory processes consist of cell mediators, both within the central nervous system and the periphery, that play vital roles in regulating the response to brain injury. Further, neuroinflammation is influenced by many biopsychosocial variables present in most athletic populations. In this commentary, we propose that future fluid biomarker research should take a systems biology approach in the context of the neuroinflammatory response to SRC. We highlight how biological variables, such as age, sex, immune challenges, and hypothalamic-pituitary-adrenal (HPA)-axis responses to stress, may alter neuroinflammation. Further, we underscore the importance of accounting for health and lifestyle variables, such as diet, exercise, sleep, and pre-morbid medical factors, when measuring inflammatory markers of SRC. To successfully move toward clinical translation, fluid biomarker research should take a more holistic approach in study design and data interpretation, collecting information on hidden variables that may be influencing the neuroinflammatory response to SRC.

Plasma miRNA profile at COVID-19 onset predicts severity status and mortality

BACKGROUND

MicroRNAs (miRNAs) have a crucial role in regulating immune response against infectious diseases, showing changes early in disease onset and before the detection of the pathogen. Thus, we aimed to analyze the plasma miRNA profile at COVID-19 onset to identify miRNAs as early prognostic biomarkers of severity and survival.

METHODS AND RESULTS

Plasma miRNome of 96 COVID-19 patients that developed asymptomatic/mild, moderate and severe disease was sequenced together with a group of healthy controls. Plasma immune-related biomarkers were also assessed. COVID-19 patients showed 200 significant differentially expressed (SDE) miRNAs concerning healthy controls, with upregulated putative targets of SARS-CoV-2, and inflammatory miRNAs. Among COVID-19 patients, 75 SDE miRNAs were observed in asymptomatic/mild compared to symptomatic patients, which were involved in platelet aggregation and cytokine pathways, among others. Moreover, 137 SDE miRNAs were identified between severe and moderate patients, where miRNAs targeting the SARS CoV-2 genome were the most strongly disrupted. Finally, we constructed a mortality predictive risk score (miRNA-MRS) with ten miRNAs. Patients with higher values had a higher risk of 90-days mortality (hazard ratio=4.60; p-value<0.001). Besides, the discriminant power of miRNA-MRS was significantly higher than the observed for age and gender (AUROC=0.970 vs. 0.881; p=0.042).

CONCLUSIONS

SARS-CoV-2 infection deeply disturbs the plasma miRNome from an early stage of COVID-19, making miRNAs highly valuable as early predictors of severity and mortality.

The role of isoflavones in augmenting the effects of radiotherapy

Cancer is one of the major health problems and the second cause of death worldwide behind heart disease. The traditional soy diet containing isoflavones, consumed by the Asian population in China and Japan has been identified as a protective factor from hormone-related cancers. Over the years the research focus has shifted from emphasizing the preventive effect of isoflavones from cancer initiation and promotion to their efficacy against established tumors along with chemo- and radiopotentiating effects. Studies performed in mouse models and results of clinical trials emphasize that genistein or a mixture of isoflavones, containing in traditional soy diet, could be utilized to both potentiate the response of cancer cells to radiotherapy and reduce radiation-induced toxicity in normal tissues. Currently ongoing clinical research explores a potential of another significant isoflavone, idronoxil, also known as phenoxodiol, as radiation enhancing agent. In the light of the recent clinical findings, this article reviews the accumulated evidence which support the clinically desirable interactions of soy isoflavones with radiation therapy resulting in improved tumor treatment. This review discusses important aspects of the development of isoflavones as anticancer agents, and mechanisms potentially relevant to their activity in combination with radiation therapy of cancer. It gives a critical overview of studies characterizing isoflavone targets such as topoisomerases, ENOX2/PMET, tyrosine kinases and ER receptor signaling, and cellular effects on the cell cycle, DNA damage, cell death, and immune responses.

Tissue-resident immunity in the lung: a first-line defense at the environmental interface

The lung is a vital organ that incessantly faces external environmental challenges. Its homeostasis and unimpeded vital function are ensured by the respiratory epithelium working hand in hand with an intricate fine-tuned tissue-resident immune cell network. Lung tissue-resident immune cells span across the innate and adaptive immunity and protect from infectious agents but can also prove to be pathogenic if dysregulated. Here, we review the innate and adaptive immune cell subtypes comprising lung-resident immunity and discuss their ontogeny and role in distinct respiratory diseases. An improved understanding of the role of lung-resident immunity and how its function is dysregulated under pathological conditions can shed light on the pathogenesis of respiratory diseases.

Nanoparticle-Induced Airway Eosinophilia Is Independent of ILC2 Signaling but Associated With Sex Differences in Macrophage Phenotype Development

The majority of lung diseases occur with a sex bias in terms of prevalence and/or severity. Previous studies demonstrated that, compared with males, female mice develop greater eosinophilic inflammation in the airways after multiwalled carbon nanotube (MWCNT) exposure. However, the mechanism by which this sex bias occurs is unknown. Two immune cells that could account for the sex bias are type II innate lymphoid cells (ILC2s) and alveolar macrophages (AMs). In order to determine which immune cell type was responsible for MWCNT-induced airway eosinophil recruitment and subsequent sex differences in inflammation and disease, male and female C57BL/6 mice were exposed to MWCNTs (2 mg/kg) via oropharyngeal aspiration, and the respiratory immune response was assessed 7 d later. Greater eosinophilia and eotaxin 2 levels were observed in MWCNT-treated females and corresponded with greater changes in airway hyperresponsiveness than those in MWCNT-treated males. In MWCNT-treated females, there was a significant increase in the frequency of ILC2s within the lungs compared with control animals. However, depletion of ILC2s via α-CD90.2 administration did not decrease eosinophil recruitment 24 h and 7 d after MWCNT exposure. AMs isolated from control and MWCNT-treated animals demonstrated that M2a macrophage phenotype gene expression, ex vivo cytokine production, and activation of (p)STAT6 were upregulated to a significantly greater degree in MWCNT-treated females than in males. Our findings suggest that sex differences in AM phenotype development, not ILC2 signaling, are responsible for the observed female bias in eosinophilic inflammation after MWCNT inhalation.

Sex-Related Factors in Cardiovascular Complications Associated to COVID-19

Coronavirus disease 2019 (COVID-19), the pandemic infection caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), presents with an extremely heterogeneous spectrum of symptoms and signs. The clinical manifestations seem to be correlated with disease severity. COVID-19 susceptibility and mortality show a significant sex imbalance, with men being more prone to infection and showing a higher rate of hospitalization and mortality compared to women. Such variability can be ascribed to both sex-related biological factors and gender-related behavioral cues. This review will discuss the potential mechanisms accounting for sex/gender influence in vulnerability to COVID-19. Cardiovascular diseases play a central role in determining COVID-19 outcome, whether they are pre-existent or arose upon infection. We will pay particular attention to the impact of sex and gender on cardiovascular manifestations related to COVID-19. Finally, we will discuss the sex-dependent variability in some biomarkers for the evaluation of COVID-19 infection and prognosis. The aim of this work is to highlight the significance of gendered medicine in setting up personalized programs for COVID-19 prevention, clinical evaluation and treatment.

Predisposing factors to acquisition of acute respiratory tract infections in the community: a systematic review and meta-analysis

Background

Preventing respiratory tract infections (RTIs) could have profound effects on quality of life, primary care workload, antibiotic prescribing and stewardship. We aimed to identify factors that increase and decrease RTI acquisition within Organisation for Economic Cooperation and Development (OECD) member countries.

Methods

Systematic search of Medline, Embase, Cochrane and ISI Web of Knowledge for studies conducted up to July 2020 reporting predisposing factors for community RTI acquisition. Pooled odds ratios were calculated using a random-effects model.

Results

23 studies investigated risk factors associated with community-acquired pneumonia (n = 15); any RTI (n = 4); influenza like illness (n = 2); and lower RTI (n = 2). Demographic, lifestyle and social factors were: underweight BMI (pooled odds ratio (OR_p 2.14, 95% CI 1.58 to 2.70, p = 0.97); male sex (OR_p 1.30, 95% CI 1.27 to 1.33, p = 0.66); contact with pets (OR_p 1.35, 95% CI 1.16 to 1.54, p = 0.72); contact with children (OR_p 1.35, 95% CI 1.15 to 1.56, p = 0.05); and ex-smoking status (OR_p 1.57, 95% CI 1.26 to 1.88, p = 0.76). Health-related factors were: chronic liver condition (OR_p 1.30, 95% CI 1.09 to 1.50, p = 0.34); chronic renal condition (OR_p 1.47, 95% CI 1.09 to 1.85, p = 0.14); and any hospitalisation in previous five years (OR_p 1.64, 95% CI 1.46 to 1.82, p = 0.66).

Conclusions

We identified several modifiable risk factors associated with increased likelihood of acquiring RTIs in the community, including low BMI, contact with children and pets. Modification of risk factors and increased awareness of vulnerable groups could reduce morbidity, mortality and antibiotic use associated with RTIs.

PROSPERO registration

CRD42019134176.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06954-3.