Genomics of sex hormone receptor signaling in hepatic sexual dimorphism

Estrogen receptor α suppresses hepatocellular carcinoma by restricting M2 macrophage infiltration through the YAP-CCL2 axis

PURPOSE

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide, with significant differences in incidence and outcomes between men and women. Estrogen receptor alpha (ERα) expression is associated with sex-based differences and poor prognostic outcomes in HCC. However, the detailed function of ERα in the tumor microenvironment of HCC remains unclear.

METHODS

Bioinformatics analysis of differentially expressed genes in HCC samples was performed from publicly available databases, and ERα was selected. The function of ERα was examined in the cell experiments. A co-culture system was built to study function of ERα-treated liver cells on macrophages in vitro. The precise mechanism was determined using quantitative real-time PCR, western blotting, immunohistochemistry, mass spectrometry, co-immunoprecipitation, and dual-luciferase reporter assay.

RESULTS

ERα played an important role in the pathogenesis of sexual dimorphism in HCC. ERα mainly acted on macrophages in the tumor microenvironment (TME) of HCC and reduced M2 macrophage infiltration through CCL2. By acting on NF2 and 14-3-3theta, ERα enhanced YAP phosphorylation and attenuated the nuclear translocation of YAP, thereby suppressing CCL2 expression. It also acted as a transcription factor that regulated CCL2 expression at the transcriptional level.

CONCLUSION

ERα/YAP/CCL2 signaling reduced M2 macrophages infiltration to inhibit HCC progression, revealing the effect of ERα in cancer cells on immune cells in HCC microenvironment.

Chr23-miR-200s and Dmrt1 Control Sexually Dimorphic Trade-Off Between Reproduction and Growth in Zebrafish

In animals, a trade-off exists between reproduction and growth, which are the most fundamental traits. Males and females exhibit profound differences in reproduction and growth in fish species. However, the precise molecular mechanism governing this phenomenon is still not clear. Here, we uncovered that chr23-miR-200s and dmrt1 knockout specifically caused an impairment in reproduction and an increase in body growth in female and male zebrafish, respectively. Chr23-miR-200s and Dmrt1 directly regulate the stat5b gene by targeting its 3'UTR and promoter. The loss of stat5b completely abolished the elevated growth performance in chr23-miR-200s-KO or dmrt1-/- zebrafish. Moreover, the dmrt1 transgenic zebrafish had significantly lower body length and body weight than the control males, accompanied by a significant reduction in stat5b expression in the liver of transgenic fish. In summary, our study proposes a regulatory model elucidating the roles of chr23-miR-200s and Dmrt1 in controlling the sexually dimorphic trade-off between reproduction and growth.

Therapeutic prospects of sex hormone receptor signaling in hormone-responsive cancers

Globally, hormone-responsive cancers afflict millions of people contributing to cancer-related morbidity and mortality. While hormone-responsive cancers overburden patients, their close families, and even health budgets at the local levels, knowledge of these cancers particularly their biology and possible avenues for therapy remains poorly exploited. Herewith, this review highlights the role of sex hormones (estrogens and androgens) in the pathophysiology of hormone-responsive cancers and the exploration of therapeutic targets. Major scientific databases including but not limited to Scopus, PubMed, Science Direct, Web of Science core collections, and Google Scholar were perused using a string of search terms: Hormone-responsive cancers, androgens and cancers, estrogens and cancer, androgen receptor signalling, estrogen receptor signalling, etc.

Sex hormones differently regulate lipid metabolism genes in primary human hepatocytes

BACKGROUND

Prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) is higher in men than in women. Hormonal and genetic causes may account for the sex differences in MASLD. Current human in vitro liver models do not sufficiently take the influence of biological sex and sex hormones into consideration.

METHODS

Primary human hepatocytes (PHHs) were isolated from liver specimen of female and male donors and cultured with sex hormones (17β-estradiol, testosterone and progesterone) for up to 72 h. mRNA expression levels of 8 hepatic lipid metabolism genes were analyzed by RT-qPCR. Sex hormones and their metabolites were determined in cell culture supernatants by LC-MS analyses.

RESULTS

A sex-specific expression was observed for LDLR (low density lipoprotein receptor) with higher mRNA levels in male than female PHHs. All three sex hormones were metabolized by PHHs and the effects of hormones on gene expression levels varied depending on hepatocyte sex. Only in female PHHs, 17β-estradiol treatment affected expression levels of PPARA (peroxisome proliferator-activated receptor alpha), LIPC (hepatic lipase) and APOL2 (apolipoprotein L2). Further changes in mRNA levels of female PHHs were observed for ABCA1 (ATP-binding cassette, sub-family A, member 1) after testosterone and for ABCA1, APOA5 (apolipoprotein A-V) and PPARA after progesterone treatment. Only the male PHHs showed changing mRNA levels for LDLR after 17β-estradiol and for APOA5 after testosterone treatment.

CONCLUSIONS

Male and female PHHs showed differences in their expression levels of hepatic lipid metabolism genes and their responsiveness towards sex hormones. Thus, cellular sex should be considered, especially when investigating the pathophysiological mechanisms of MASLD.

Nomogram built based on machine learning to predict recurrence in early-stage hepatocellular carcinoma patients treated with ablation

Introduction

To analyze the risk factors affecting recurrence in early-stage hepatocellular carcinoma (HCC) patients treated with ablation and then establish a nomogram to provide a clear and accessible representation of the patients' recurrence risk.

Methods

Collect demographic and clinical data of 898 early-stage HCC patients who underwent ablation treatment at Beijing You'an Hospital, affiliated with Capital Medical University from January 2014 to December 2022. Patients admitted from 2014 to 2018 were included in the training cohort, while 2019 to 2022 were in the validation cohort. Lasso and Cox regression was used to screen independent risk factors for HCC patients recurrence, and a nomogram was then constructed based on the screened factors.

Results

Age, gender, Barcelona Clinic Liver Cancer (BCLC) stage, tumor size, globulin (Glob) and γ-glutamyl transpeptidase (γ-GT) were finally incorporated in the nomogram for predicting the recurrence-free survival (RFS) of patients. We further confirmed that the nomogram has optimal discrimination, consistency and clinical utility by the C-index, Receiver Operating Characteristic Curve (ROC), calibration curve and Decision Curve Analysis (DCA). Moreover, we divided the patients into different risk groups and found that the nomogram can effectively identify the high recurrence risk patients by the Kaplan-Meier curves.

Conclusion

This study developed a nomogram using Lasso-Cox regression to predict RFS in early-stage HCC patients following ablation, aiding clinicians in identifying high-risk groups for personalized follow-up treatments.

High-pressure Hydrodynamic Injection as a Method of Establishing Hepatitis B Virus Infection in Mice

Among several existing mouse models for hepatitis B virus (HBV) infection, the high-pressure hydrodynamic injection (HDI) method is frequently used in HBV research due to its economic advantages and ease of implementation. The use of the HDI method is influenced by factors such as mouse genetic background, age, sex, and the type of HBV plasmid used. This overview provides a multidimensional analysis and comparison of various factors that influence the effectiveness of the HBV mouse model established through HDI. The goal is to provide a summary of information for researchers who create HBV models in mice.

Expression Analysis of Lipocalin 2 (LCN2) in Reproductive and Non-Reproductive Tissues of Esr1-Deficient Mice

Estrogen receptor alpha (ERα) is widely expressed in reproductive organs, but also in non-reproductive tissues of females and males. There is evidence that lipocalin 2 (LCN2), which has diverse immunological and metabolic functions, is regulated by ERα in adipose tissue. However, in many other tissues, the impact of ERα on LCN2 expression has not been studied yet. Therefore, we used an Esr1-deficient mouse strain and analyzed LCN2 expression in reproductive (ovary, testes) and non-reproductive tissues (kidney, spleen, liver, lung) of both sexes. Tissues collected from adult wild-type (WT) and Esr1-deficient animals were analyzed by immunohistochemistry, Western blot analysis, and RT-qPCR for Lcn2 expression. In non-reproductive tissues, only minor genotype- or sex-specific differences in LCN2 expression were detected. In contrast, significant differences in LCN2 expression were observed in reproductive tissues. Particularly, there was a strong increase in LCN2 in Esr1-deficient ovaries when compared to WTs. In summary, we found an inverse correlation between the presence of ERα and the expression of LCN2 in testes and ovaries. Our results provide an important basis to better understand LCN2 regulation in the context of hormones and in health and disease.

Clinical Concerns on Sex Steroids Variability in Cisgender and Transgender Women Athletes

In the female athletic community, there are several endogenous and exogenous variables that influence the status of the hypothalamus-pituitary-ovarian axis and serum sex steroid hormones concentrations (e. g., 17β-estradiol, progesterone, androgens) and their effects. Moreover, female athletes with different sex chromosome abnormalities exist (e. g., 46XX, 46XY, and mosaicism). Due to the high variability of sex steroid hormones serum concentrations and responsiveness, female athletes may have different intra- and inter-individual biological and functional characteristics, health conditions, and sports-related health risks that can influence sports performance and eligibility. Consequently, biological, functional, and/or sex steroid differences may exist in the same and in between 46XX female athletes (e. g., ovarian rhythms, treated or untreated hypogonadism and hyperandrogenism), between 46XX and 46XY female athletes (e. g., treated or untreated hyperandrogenism/disorders of sexual differentiation), and between transgender women and eugonadal cisgender athletes. From a healthcare perspective, dedicated physicians need awareness, knowledge, and an understanding of sex steroid hormones' variability and related health concerns in female athletes to support physiologically healthy, safe, fair, and inclusive sports participation. In this narrative overview, we focus on the main clinical relationships between hypothalamus-pituitary-ovarian axis function, endogenous sex steroids and health status, health risks, and sports performance in the heterogeneous female athletic community.

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.

Androgen receptor functions in pericentral hepatocytes to decrease gluconeogenesis and avoid hyperglycemia and obesity in male mice

BACKGROUND

Although the impact of hepatic androgen receptor (AR) pathway on liver pathogenesis was documented, its physiological function in normal liver is remained unclear. This study aims to investigate if hepatic AR acts on metabolism, the major liver function, using a hepatic-specific AR-transgenic (H-ARTG) mouse model.

METHODS

We established the albumin promoter driven H-ARTG mice and included wild type (WT) and H-ARKO mice for study. The body weight, specific metabolic parameters and results from various tolerance tests were compared in different groups of mice fed a chow diet, from 2 to 18 months of age. Glucose feeding and insulin treatment were used to study the expression and zonal distribution pattern of AR and related genes in liver at different prandial stages.

RESULTS

The body weight of H-ARTG mice fed a chow diet was 15 % lower than that of wild-type mice, preceded by lower blood glucose and liver triglyceride levels caused by AR reduced hepatic gluconeogenesis. The opposite phenotypes identified in H-ARKO and castrated H-ARTG mice support the critical role of activated AR in decreasing gluconeogenesis and triglyceride levels in liver. Hepatic AR acting by enhancing the expression of cytosolic glycerol-3-phosphate dehydrogenase (cGPDH), a key of glycerophosphate shuttle, was identified as one mechanism to decrease gluconeogenesis from glycerol. We further found AR normally expressed in zone 3 of hepatic lobules. Its level fluctuates dependent on the demand of glucose, decreased by fasting but increased by glucose uptake or insulin stimulation.

CONCLUSION

AR is a newly identified zone 3 hepatic gene with function in reducing blood glucose and body weight in mice. It suggests that stabilization of hepatic AR is a new direction to prevent hyperglycemia, obesity and nonalcoholic fatty liver disease (NAFLD) in males.

Morphofunctional State and Circadian Rhythms of the Liver of Female Rats under the Influence of Chronic Alcohol Intoxication and Constant Lighting

A separate and combined effect of constant illumination and chronic alcohol intoxication (CAI) on diurnal dynamics of micromorphometric parameters of hepatocytes in female Wistar rats and p53, Ki-67, PER2, BMAL1, and ADH5 expression in these cells were studied. The increase in apoptotic activity and proliferation in all animals under the action of chronodestructors is shown. All experimental animals showed a decrease in BMAL1 expression and increase in PER2 expression; ADH5 is overexpressed under the influence of ethanol. Circadian rhythms (CRs) of BMAL1, PER2, p53, and Ki-67 expression persist in all groups, except combined action of chronodestructors, and ADH5 CRs persist in all groups—thus, these rhythms in females are quite stable. CRs of the hepatocyte nuclei area are preserved in all the studied groups, although they undergo a significant shift. At the same time, the CRs of the hepatocyte area are destroyed under the action of light, both independently and in combination with CAI, and the CR of the nuclear-cytoplasmic ratio (NCR) is destroyed by exposure to CAI. It can be assumed that CRs of the hepatocyte area are significantly affected by dark deprivation and NCR rhythm is sensitive to ethanol consumption, while the stability of studied genes’ expression rhythms at separate influences of studied chronodestructors is maintained by yet unknown adaptation mechanisms. It is necessary to note that, according to our previous studies of male rats, rat females show significantly greater stability of the studied CRs.

Tff3 Deficiency Protects against Hepatic Fat Accumulation after Prolonged High-Fat Diet

Trefoil factor 3 (Tff3) protein is a small secretory protein expressed on various mucosal surfaces and is involved in proper mucosal function and recovery via various mechanisms, including immune response. However, Tff3 is also found in the bloodstream and in various other tissues, including the liver. Its complete attenuation was observed as the most prominent event in the early phase of diabetes in the polygenic Tally Ho mouse model of diabesity. Since then, its role in metabolic processes has emerged. To elucidate the complex role of Tff3, we used a new Tff3-deficient mouse model without additional metabolically relevant mutations (Tff3-/-/C57BL/6NCrl) and exposed it to a high-fat diet (HFD) for a prolonged period (8 months). The effect was observed in male and female mice compared to wild-type (WT) counter groups (n = 10 animals per group). We monitored the animals’ general metabolic parameters, liver morphology, ultrastructure and molecular genes in relevant lipid and inflammatory pathways. Tff3-deficient male mice had reduced body weight and better glucose utilization after 17 weeks of HFD, but longer HFD exposure (32 weeks) resulted in no such change. We found a strong reduction in lipid accumulation in male Tff3-/-/C57BL/6NCrl mice and a less prominent reduction in female mice. This was associated with downregulated peroxisome proliferator-activated receptor gamma (Pparγ) and upregulated interleukin-6 (Il-6) gene expression, although protein level difference did not reach statistical significance due to higher individual variations. Tff3-/-/C57Bl6N mice of both sex had reduced liver steatosis, without major fatty acid content perturbations. Our research shows that Tff3 protein is clearly involved in complex metabolic pathways. Tff3 deficiency in C57Bl6N genetic background caused reduced lipid accumulation in the liver; further research is needed to elucidate its precise role in metabolism-related events.

Long or Irregular Menstrual Cycles and Risk of Prevalent and Incident Nonalcoholic Fatty Liver Disease

CONTEXT

The association of menstrual cycle length and irregularity with the risk of non-alcoholic fatty liver disease (NAFLD) is unknown.

OBJECTIVE

We examined this association in large cross-sectional and cohort studies.

METHODS

The cross-sectional study included 72 092 women younger than 40 years who underwent routine health examinations; the longitudinal analysis included the subset of 51 118 women without NAFLD at baseline. Long or irregular cycles were defined as menstrual cycles of 40 days or longer or too irregular to estimate. Abdominal ultrasonography was performed to identify NAFLD. Multivariable Cox proportional hazard regression analyses were performed to estimate hazard ratios (HRs) and 95% CIs for incident NAFLD according to menstrual cycle regularity and length, with 26- to 30-day cycles as the reference.

RESULTS

At baseline, 27.7% had long or irregular menstrual cycles and 7.1% had prevalent NAFLD. Long or irregular menstrual cycles were positively associated with prevalent NAFLD. During a median follow-up of 4.4 years, incident NAFLD occurred in 8.9% of women. After adjustment for age, body mass index, insulin resistance, and other confounders, the multivariable-adjusted HR for NAFLD comparing long or irregular menstrual cycles to the reference group was 1.22 (95% CI, 1.14-1.31); this association strengthened in the time-dependent analysis with an HR of 1.49 (95% CI, 1.38-1.60).

CONCLUSION

Long or irregular menstrual cycles were associated with increased risk of both prevalent and incident NAFLD in young, premenopausal women. Women with long or irregular menstrual cycles may benefit from lifestyle modification advice to reduce the risk of NAFLD and associated cardiometabolic diseases.

Relative contributions of sex hormones, sex chromosomes, and gonads to sex differences in tissue gene regulation

Sex differences in physiology and disease in mammals result from the effects of three classes of factors that are inherently unequal in males and females: reversible (activational) effects of gonadal hormones, permanent (organizational) effects of gonadal hormones, and cell-autonomous effects of sex chromosomes, as well as genes driven by these classes of factors. Often, these factors act together to cause sex differences in specific phenotypes, but the relative contribution of each and the interactions among them remain unclear. Here, we used the four core genotypes (FCG) mouse model with or without hormone replacement to distinguish the effects of each class of sex-biasing factors on transcriptome regulation in liver and adipose tissues. We found that the activational hormone levels have the strongest influence on gene expression, followed by the organizational gonadal sex effect, and last, sex chromosomal effect, along with interactions among the three factors. Tissue specificity was prominent, with a major impact of estradiol on adipose tissue gene regulation and of testosterone on the liver transcriptome. The networks affected by the three sex-biasing factors include development, immunity and metabolism, and tissue-specific regulators were identified for these networks. Furthermore, the genes affected by individual sex-biasing factors and interactions among factors are associated with human disease traits such as coronary artery disease, diabetes, and inflammatory bowel disease. Our study offers a tissue-specific account of the individual and interactive contributions of major sex-biasing factors to gene regulation that have broad impact on systemic metabolic, endocrine, and immune functions.

Constitutively Active STAT5b Feminizes Mouse Liver Gene Expression

STAT5 is an essential transcriptional regulator of the sex-biased actions of GH in the liver. Delivery of constitutively active STAT5 (STAT5CA) to male mouse liver using an engineered adeno-associated virus with high tropism for the liver is shown to induce widespread feminization of the liver, with extensive induction of female-biased genes and repression of male-biased genes, largely mimicking results obtained when male mice are given GH as a continuous infusion. Many of the STAT5CA-responding genes were associated with nearby (< 50 kb) sites of STAT5 binding to liver chromatin, supporting the proposed direct role of persistently active STAT5 in continuous GH-induced liver feminization. The feminizing effects of STAT5CA were dose-dependent; moreover, at higher levels, STAT5CA overexpression resulted in some histopathology, including hepatocyte hyperplasia, and increased karyomegaly and multinuclear hepatocytes. These findings establish that the persistent activation of STAT5 by GH that characterizes female liver is by itself sufficient to account for the sex-dependent expression of a majority of hepatic sex-biased genes. Moreover, histological changes seen when STAT5CA is overexpressed highlight the importance of carefully evaluating such effects before considering STAT5 derivatives for therapeutic use in treating liver disease.

Krüppel-like Factor 9 (KLF9) Suppresses Hepatocellular Carcinoma (HCC)-Promoting Oxidative Stress and Inflammation in Mice Fed High-Fat Diet

Obesity, oxidative stress, and inflammation are risk factors for hepatocellular carcinoma (HCC). We examined, in mice, the effects of Krüppel-like factor 9 (KLF9) knockout on: adiposity, hepatic and systemic oxidative stress, and hepatic expression of pro-inflammatory and NOX/DUOX family genes, in a high-fat diet (HFD) context. Male and female Klf9^+/+ (wild type, WT) and Klf9^-/- (knockout, KO) mice were fed HFD (beginning at age 35 days) for 12 weeks, after which liver and adipose tissues were obtained, and serum adiponectin and leptin levels, liver fat content, and markers of oxidative stress evaluated. Klf9^-/- mice of either sex did not exhibit significant alterations in weight gain, adipocyte size, adipokine levels, or liver fat content when compared to WT counterparts. However, Klf9^-/- mice of both sexes had increased liver weight/size (hepatomegaly). This was accompanied by increased hepatic oxidative stress as indicated by decreased GSH/GSSG ratio and increased homocysteine, 3-nitrotyrosine, 3-chlorotyrosine, and 4HNE content. Decreased GSH to GSSG ratio and a trend toward increased homocysteine levels were observed in the corresponding Klf9^-/- mouse serum. Gene expression analysis showed a heightened pro-inflammatory state in livers from Klf9^-/- mice. KLF9 suppresses hepatic oxidative stress and inflammation, thus identifying potential mechanisms for KLF9 suppression of HCC and perhaps cancers of other tissues.

Hepatic glucocorticoid-induced transcriptional regulation is androgen-dependent after chronic but not acute glucocorticoid exposure

Glucocorticoids exert their pleiotropic effects by activating the glucocorticoid receptor (GR), which is expressed throughout the body. GR-mediated transcription is regulated by a multitude of tissue- and cell type-specific mechanisms, including interactions with other transcription factors such as the androgen receptor (AR). We previously showed that the transcription of canonical glucocorticoid-responsive genes is dependent on active androgen signaling, but the extent of this glucocorticoid-androgen crosstalk warrants further investigation. In this study, we investigated the overall glucocorticoid-androgen crosstalk in the hepatic transcriptome. Male mice were exposed to GR agonist corticosterone and AR antagonist enzalutamide in order to determine the extent of androgen-dependency after acute and chronic exposure. We found that a substantial proportion of the hepatic transcriptome is androgen-dependent after chronic exposure, while after acute exposure the transcriptomic effects of glucocorticoids are largely androgen-independent. We propose that prolonged glucocorticoid exposure triggers a gradual upregulation of AR expression, instating a situation of androgen dependence which is likely not driven by direct AR-GR interactions. This indirect mode of glucocorticoid-androgen interaction is in accordance with the absence of enriched AR DNA-binding near AR-dependent corticosterone-regulated genes after chronic exposure. In conclusion, we demonstrate that glucocorticoid effects and their interaction with androgen signaling are dependent on the duration of exposure and believe that our findings contribute to a better understanding of hepatic glucocorticoid biology in health and disease.

Hepatic sexual dimorphism - implications for non-alcoholic fatty liver disease

The liver is often thought of as a single functional unit, but both its structural and functional architecture make it highly multivalent and adaptable. In any given physiological situation, the liver can maintain metabolic homeostasis, conduct appropriate inflammatory responses, carry out endobiotic and xenobiotic transformation and synthesis reactions, as well as store and release multiple bioactive molecules. Moreover, the liver is a very resilient organ. This resilience means that chronic liver diseases can go unnoticed for decades, yet culminate in life-threatening clinical complications once the adaptive capacity of the liver is overwhelmed. Non-alcoholic fatty liver disease (NAFLD) predisposes individuals to cirrhosis and increases liver-related and cardiovascular disease-related mortality. This Review discusses the accumulating evidence of sexual dimorphism in NAFLD, which is currently rarely considered in preclinical and clinical studies. Increased awareness of the mechanistic causes of hepatic sexual dimorphism could lead to improved understanding of the biological processes that are dysregulated in NAFLD, to the identification of relevant therapeutic targets and to improved risk stratification of patients with NAFLD undergoing therapeutic intervention.

Beyond the X Factor: Relevance of Sex Hormones in NAFLD Pathophysiology

Non-alcoholic fatty liver disease (NAFLD) is a major health issue worldwide, being frequently associated with obesity, unbalanced dietary regimens, and reduced physical activity. Despite their greater adiposity and reduced physical activity, women show a lower risk of developing NAFLD in comparison to men, likely a consequence of a sex-specific regulation of liver metabolism. In the liver, sex differences in the uptake, synthesis, oxidation, deposition, and mobilization of lipids, as well as in the regulation of inflammation, are associated with differences in NAFLD prevalence and progression between men and women. Given the major role of sex hormones in driving hepatic sexual dimorphism, this review will focus on the role of sex hormones and their signaling in the regulation of hepatic metabolism and in the molecular mechanisms triggering NAFLD development and progression.

The Influence of Glucocorticoid Receptor on Sex Differences of Gene Expression Profile in Skeletal Muscle

Skeletal muscle functions as a locomotory system and maintains whole-body metabolism. Sex differences in such skeletal muscle morphology and function have been documented; however, their underlying mechanisms remain elusive. Glucocorticoids are adrenocortical hormones maintaining homeostasis, including regulating whole-body energy metabolism in addition to stress response. In skeletal muscle, glucocorticoids can reduce the synthesis of muscle proteins and simultaneously accelerate the breakdown of proteins to regulate skeletal muscle mass and energy metabolism via a transcription factor glucocorticoid receptor (GR). We herein evaluated the related contributions of the GR to sex differences of gene expression profiles in skeletal muscle using GR-floxed (GRf/f) and skeletal muscle-specific GR knockout (GRmKO) mice. There were no differences in GR mRNA and protein expression levels in gastrocnemius muscle between males and females. A DNA microarray analysis using gastrocnemius muscle from GRf/f and GRmKO mice revealed that, although most gene expression levels were identical in both sexes, genes related to cholesterol and apolipoprotein synthesis and fatty acid biosynthesis and the immunological system were predominantly expressed in males and females, respectively, in GRf/f but not in GRmKO mice. Moreover, many genes were up-regulated in response to starvation in GRf/f but not in GRmKO mice, many of which were sex-independent and functioned to maintain homeostasis, while genes that showed sex dominance related to a variety of functions. Although the genes expressed in skeletal muscle may be predominantly sex-independent, sex-dominant genes may relate to sex differences in energy metabolism and the immune system and could be controlled by the GR.

Sex-dependent dynamics of metabolism in primary mouse hepatocytes

The liver is one of the most sexually dimorphic organs. The hepatic metabolic pathways that are subject to sexual dimorphism include xenobiotic, amino acid and lipid metabolism. Non-alcoholic fatty liver disease and hepatocellular carcinoma are among diseases with sex-dependent prevalence, progression and outcome. Although male and female livers differ in their abilities to metabolize foreign compounds, including drugs, sex-dependent treatment and pharmacological dynamics are rarely applied in all relevant cases. Therefore, it is important to consider hepatic sexual dimorphism when developing new treatment strategies and to understand the underlying mechanisms in model systems. We isolated primary hepatocytes from male and female C57BL6/N mice and examined the sex-dependent transcriptome, proteome and extracellular metabolome parameters in the course of culturing them for 96 h. The sex-specific gene expression of the general xenobiotic pathway altered and the female-specific expression of Cyp2b13 and Cyp2b9 was significantly reduced during culture. Sex-dependent differences of several signaling pathways increased, including genes related to serotonin and melatonin degradation. Furthermore, the ratios of male and female gene expression were inversed for other pathways, such as amino acid degradation, beta-oxidation, androgen signaling and hepatic steatosis. Because the primary hepatocytes were cultivated without the influence of known regulators of sexual dimorphism, these results suggest currently unknown modulatory mechanisms of sexual dimorphism in vitro. The large sex-dependent differences in the regulation and dynamics of drug metabolism observed during cultivation can have an immense influence on the evaluation of pharmacodynamic processes when conducting initial preclinical trials to investigate potential new drugs.

Endocrine disrupting chemicals and metabolic disorders in the liver: What if we also looked at the female side?

Endocrine disrupting chemicals (EDCs) are linked to the worldwide epidemic incidence of metabolic disorders and fatty liver diseases, which affects quality of life and represents a high economic cost to society. Energy homeostasis exhibits strong sexual dimorphic traits, and metabolic organs respond to EDCs depending on sex, such as the liver, which orchestrates both drug elimination and glucose and lipid metabolism. In addition, fatty liver diseases show a strong sexual bias, which in part could also originate from sex differences observed in gut microbiota. The aim of this review is to highlight significant differences in endocrine and metabolic aspects of the liver, between males and females throughout development and into adulthood. It is also to illustrate how the male and female liver differently cope with exposure to various EDCs such as bisphenols, phthalates and persistent organic chemicals in order to draw attention to the need to include both sexes in experimental studies. Interesting data come from analyses of the composition and diversity of the gut microbiota in males exposed to the mentioned EDCs showing significant correlations with hepatic lipid accumulation and metabolic disorders but information on females is lacking or incomplete. As industrialization increases, the list of anthropogenic chemicals to which humans will be exposed will also likely increase. In addition to strengthening existing regulations, encouraging populations to protect themselves and promoting the substitution of harmful chemicals with safe products, innovative strategies based on sex differences in the gut microbiota and in the gut-liver axis could be optimistic outlook.

Hepatic steatosis and steatohepatitis: a functional meta-analysis of sex-based differences in transcriptomic studies

Background

Previous studies have described sex-based differences in the epidemiological and clinical patterns of non-alcoholic fatty liver disease (NAFLD); however, we understand relatively little regarding the underlying molecular mechanisms. Herein, we present the first systematic review and meta-analysis of NAFLD transcriptomic studies to identify sex-based differences in the molecular mechanisms involved during the steatosis (NAFL) and steatohepatitis (NASH) stages of the disease.

Methods

Transcriptomic studies in the Gene Expression Omnibus database were systematically reviewed following the PRISMA statement guidelines. For each study, NAFL and NASH in premenopausal women and men were compared using a dual strategy: gene-set analysis and pathway activity analysis. Finally, the functional results of all studies were integrated into a meta-analysis.

Results

We reviewed a total of 114 abstracts and analyzed seven studies that included 323 eligible patients. The meta-analyses identified significantly altered molecular mechanisms between premenopausal women and men, including the overrepresentation of genes associated with DNA regulation, vinculin binding, interleukin-2 responses, negative regulation of neuronal death, and the transport of ions and cations in premenopausal women. In men, we discovered the overrepresentation of genes associated with the negative regulation of interleukin-6 and the establishment of planar polarity involved in neural tube closure.

Conclusions

Our meta-analysis of transcriptomic data provides a powerful approach to identify sex-based differences in NAFLD. We detected differences in relevant biological functions and molecular terms between premenopausal women and men. Differences in immune responsiveness between men and premenopausal women with NAFLD suggest that women possess a more immune tolerant milieu, while men display an impaired liver regenerative response.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13293-021-00368-1.

Effect of menopausal status on the survival and recurrence of sex-classified hepatocellular carcinoma after liver resection: a case-matched study with propensity score matching

OBJECTIVE

To investigate the impact of menopausal status on the prognosis for sex-classified Hepatocellular carcinoma (HCC) and to establish prognostic nomograms for patients after liver resection.

RESULTS

After propensity score matching (PSM), statistically significant differences in both overall survival (OS) and recurrence-free survival (RFS) were found between men and women HCC patients. Based on Cox regression analysis, these differences were evident in the normal menstruation (N) group expanded with male patients, but not in either the expanded postmenopausal (P) or intermediate (I) groups. Sex disparity was also apparent in the recurrence-free survival (RFS) of the total HCC patients. Integrated with independent factors, nomograms for the OS and RFS of the expanded N group showed higher C-indices of 0.773 and 0.724, respectively, than those of nomograms for the total patients and BCLC stage (P<0.001).

CONCLUSION

Sex disparity appears to affect both the survival and recurrence of HCC only in normal menstruation women and their matched men. For predicting survival, prognostic nomograms derived from the expanded N group of HCC patients were more accurate for patients with the same clinical conditions.

METHODS

The patients (390 females and 1920 males), who underwent curative liver resection for HCC during 2008 to 2012, were screened. The 390 women were divided into three groups: normal menstruation, intermediate, and postmenopausal. To overcome selection bias, the three groups of females were matched with males at a ratio of 1:2, using propensity score matching. Based on further Cox regression analysis, independent factors were integrated into nomograms for OS and RFS by R rms. The accuracy and discrimination of the nomograms were evaluated by the C-index, calibration curve, and decision curve analysis.

Non-alcoholic Fatty Liver Disease as a Canonical Example of Metabolic Inflammatory-Based Liver Disease Showing a Sex-Specific Prevalence: Relevance of Estrogen Signaling

There is extensive evidence supporting the interplay between metabolism and immune response, that have evolved in close relationship, sharing regulatory molecules and signaling systems, to support biological functions. Nowadays, the disruption of this interaction in the context of obesity and overnutrition underlies the increasing incidence of many inflammatory-based metabolic diseases, even in a sex-specific fashion. During evolution, the interplay between metabolism and reproduction has reached a degree of complexity particularly high in female mammals, likely to ensure reproduction only under favorable conditions. Several factors may account for differences in the incidence and progression of inflammatory-based metabolic diseases between females and males, thus contributing to age-related disease development and difference in life expectancy between the two sexes. Among these factors, estrogens, acting mainly through Estrogen Receptors (ERs), have been reported to regulate several metabolic pathways and inflammatory processes particularly in the liver, the metabolic organ showing the highest degree of sexual dimorphism. This review aims to investigate on the interaction between metabolism and inflammation in the liver, focusing on the relevance of estrogen signaling in counteracting the development and progression of non-alcoholic fatty liver disease (NAFLD), a canonical example of metabolic inflammatory-based liver disease showing a sex-specific prevalence. Understanding the role of estrogens/ERs in the regulation of hepatic metabolism and inflammation may provide the basis for the development of sex-specific therapeutic strategies for the management of such an inflammatory-based metabolic disease and its cardio-metabolic consequences.

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

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

Sex Chromosomes and Sex Phenotype Contribute to Biased DNA Methylation in Mouse Liver

Sex biases in the genome-wide distribution of DNA methylation and gene expression levels are some of the manifestations of sexual dimorphism in mammals. To advance our understanding of the mechanisms that contribute to sex biases in DNA methylation and gene expression, we conducted whole genome bisulfite sequencing (WGBS) as well as RNA-seq on liver samples from mice with different combinations of sex phenotype and sex-chromosome complement. We compared groups of animals with different sex phenotypes, but the same genetic sexes, and vice versa, same sex phenotypes, but different sex-chromosome complements. We also compared sex-biased DNA methylation in mouse and human livers. Our data show that sex phenotype, X-chromosome dosage, and the presence of Y chromosome shape the differences in DNA methylation between males and females. We also demonstrate that sex bias in autosomal methylation is associated with sex bias in gene expression, whereas X-chromosome dosage-dependent methylation differences are not, as expected for a dosage-compensation mechanism. Furthermore, we find partial conservation between the repertoires of mouse and human genes that are associated with sex-biased methylation, an indication that gene function is likely to be an important factor in this phenomenon.

Sex- and age-dependent effects of maternal organophosphate flame-retardant exposure on neonatal hypothalamic and hepatic gene expression

After the phase-out of polybrominated diphenyl ethers, their replacement compounds, organophosphate flame retardants (OPFRs) became ubiquitous in home and work environments. OPFRs, which may act as endocrine disruptors, are detectable in human urine, breast milk, and blood samples collected from pregnant women. However, the effects of perinatal OPFR exposure on offspring homeostasis and gene expression remain largely underexplored. To address this knowledge gap, virgin female mice were mated and dosed with either a sesame oil vehicle or an OPFR mixture (tris(1,3-dichloro-2-propyl)phosphate, tricresyl phosphate, and triphenyl phosphate, 1 mg/kg each) from gestational day (GD) 7 to postnatal day (PND) 14. Hypothalamic and hepatic tissues were collected from one female and one male pup per litter on PND 0 and PND 14. Expression of genes involved in energy homeostasis, reproduction, glucose metabolism, and xenobiotic metabolism were analyzed using quantitative real-time PCR. In the mediobasal hypothalamus, OPFR increased Pdyn, Tac2, Esr1, and Pparg in PND 14 females. In the liver, OPFR increased Pparg and suppressed Insr, G6pc, and Fasn in PND 14 males and increased Esr1, Foxo1, Dgat2, Fasn, and Cyb2b10 in PND 14 females. We also observed striking sex differences in gene expression that were dependent on the age of the pup. Collectively, these data suggest that maternal OPFR exposure alters hypothalamic and hepatic development by influencing neonatal gene expression in a sex-dependent manner. The long-lasting consequences of these changes in expression may disrupt puberty, hormone sensitivity, and metabolism of glucose, fatty acids, and triglycerides in the maturing juvenile.

Hepatic ERα accounts for sex differences in the ability to cope with an excess of dietary lipids

Objective

Among obesity-associated metabolic diseases, non-alcoholic fatty liver disease (NAFLD) represents an increasing public health issue due to its emerging association with atherogenic dyslipidemia and cardiovascular diseases (CVDs). The lower prevalence of NAFLD in pre-menopausal women compared with men or post-menopausal women led us to hypothesize that the female-inherent ability to counteract this pathology might strongly rely on estrogen signaling.

In female mammals, estrogen receptor alpha (ERα) is highly expressed in the liver, where it acts as a sensor of the nutritional status and adapts the metabolism to the reproductive needs. As in the male liver this receptor is little expressed, we here hypothesize that hepatic ERα might account for sex differences in the ability of males and females to cope with an excess of dietary lipids and counteract the accumulation of lipids in the liver.

Methods

Through liver metabolomics and transcriptomics we analyzed the relevance of hepatic ERα in the metabolic response of males and females to a diet highly enriched in fats (HFD) as a model of diet-induced obesity.

Results

The study shows that the hepatic ERα strongly contributes to the sex-specific response to an HFD and its action accounts for opposite consequences for hepatic health in males and females.

Conclusion

This study identified hepatic ERα as a novel target for the design of sex-specific therapies against fatty liver and its cardio-metabolic consequences.

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Hepatic ERα contributes to sex-specific response to a fat-enriched diet.

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Hepatic ERα action accounts for contrasting consequences in males and females.

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In males, hepatic ERα action does not prevent liver lipid accumulation.

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The lack of ERα is responsible for an altered plasma lipid profile in males.

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In females, liver ERα controls lipid catabolism and counteracts NAFLD development.

Effect of diet in females (F1) from prenatally undernourished mothers on metabolism and liver function in the F2 progeny is sex-specific

PURPOSE

Poor maternal nutrition sensitises to the development of metabolic diseases and obesity in adulthood over several generations. The prevalence increases when offspring is fed with a high-fat (HF) diet after weaning. This study aims to determine whether such metabolic profiles can be transmitted to the second generation and even aggravated when the mothers were exposed to overnutrition, with attention to potential sex differences.

METHODS

Pregnant Wistar rats were subjected to ad libitum (control) or 70% food-restricted diet (FR) during gestation (F0). At weaning, F1 females were allocated to three food protocols: (1) standard diet prior to and throughout gestation and lactation, (2) HF diet prior to and standard diet throughout gestation and lactation, and (3) HF diet prior to and throughout gestation and lactation. F2 offspring was studied between 16 and 32 weeks of age.

RESULTS

FR-F2 offspring on standard diet showed normal adiposity and had no significant metabolic alterations in adulthood. Maternal HF diet resulted in sex-specific effects with metabolic disturbances more apparent in control offspring exposed to HF diet during gestation and lactation. Control offspring displayed glucose intolerance associated with insulin resistance in females. Female livers overexpressed lipogenesis genes and those of males the genes involved in lipid oxidation. Gene expression was significantly attenuated in the FR livers. Increased physical activity associated with elevated corticosterone levels was observed in FR females on standard diet and in all females from overnourished mothers.

CONCLUSIONS

Maternal undernutrition during gestation (F0) improves the metabolic health of second-generation offspring with more beneficial effects in females.

Trans-acting non-synonymous variant of FOXA1 predisposes to hepatocellular carcinoma through modulating FOXA1-ERα transcriptional program and may have undergone natural selection

Interplay of pioneer transcription factor forkhead box A1 (FOXA1) and estrogen receptor has been implicated in sexual dimorphism in hepatocellular carcinoma (HCC), but etiological relevance of its polymorphism was unknown. In the case control study (1152 patients versus1242 controls), we observed significant increase in HCC susceptibility in hepatitis B virus carriers associated with a non-synonymous Thr83Ala variant of FOXA1 (odds ratio [OR], 1.28; 95% confidence interval [CI], 1.11−1.48, for Ala83-containing genotype, after validation in an independent population with 933 patients versus 1030 controls), a tightly linked (CGC)5/6or7 repeat polymorphism at its promoter (OR 1.32; 95% CI 1.10–1.60, for (CGC)6or7-repeat-containing genotype), and their combined haplotype (OR 1.50; 95% CI 1.24–1.81, for (CGC)6or7−Ala83 haplotype). The susceptible FOXA1-Ala83 impairs its interaction with ERα, attenuates transactivation toward some of their dual target genes, such as type 1 iodothyronine deiodinase, UDP glucuronosyltransferase 2 family, polypeptide B17 and sodium/taurocholate cotransporting polypeptide, but correlates with strengthened cellular expression of α-fetoprotein (AFP) and elevated AFP serum concentration in HCC patients (n = 1096). The susceptible FOXA1 cis-variant with (CGC)6or7 repeat strengthens the binding to transcription factor early growth response 1 and enhances promoter activity and gene expression. Evolutionary population genetics analyses with public datasets reveal significant population differentiation and unique haplotype structure of the derived protective FOXA1-Thr83 and suggest that it may have undergone positive natural selection in Chinese population. These findings epidemiologically highlight the functional significance of FOXA1-ERα transcriptional program and regulatory network in liver cancer development.

Coordination between the circadian clock and androgen signaling is required to sustain rhythmic expression of Elovl3 in mouse liver

ELOVL3 is a very long-chain fatty acid elongase, and its mRNA levels display diurnal rhythmic changes exclusively in adult male mouse livers. This cyclical expression of hepatic Elovl3 is potentially controlled by the circadian clock, related hormones, and transcriptional factors. It remains unknown, however, whether the circadian clock, in conjunction with androgen signaling, functions in maintaining the rhythmic expression of Elovl3 in a sexually dimorphic manner. Under either zeitgeber or circadian time, WT mouse livers exhibited a robust circadian rhythmicity in the expression of circadian clock genes and Elovl3 In contrast, male Bmal1-/- mice displayed severely weakened expression of hepatic circadian clock genes, resulting in relatively high, but nonrhythmic, Elovl3 expression levels. ChIP assays revealed that NR1D1 binds to the Elovl3 promoter upon circadian change in WT mouse livers in vivo, and a diminished binding was observed in male Bmal1-/- mouse livers. Additionally, female mouse livers exhibited constant low levels of Elovl3 expression. Castration markedly reduced Elovl3 expression levels in male mouse livers but did not disrupt circadian variation of Elovl3 Injection of female mice with 5α-dihydrotestosterone induced Elovl3 rhythmicity in the liver. In AML12 cells, 5α-dihydrotestosterone also elevated Elovl3 expression in a time-dependent manner. In contrast, flutamide efficiently attenuated this induction effect. In conclusion, a lack of either the circadian clock or androgen signaling impairs hepatic Elovl3 expression, highlighting the observation that coordination between the circadian clock and androgen signaling is required to sustain the rhythmic expression of Elovl3 in mouse liver.

Personalized therapy when tackling nonalcoholic fatty liver disease: a focus on sex, genes, and drugs

INTRODUCTION

Nonalcoholic fatty liver disease (NAFLD) is the most frequent liver disease in the world. It describes a term for a group of hepatic diseases including steatosis, fibrosis, and cirrhosis that can finally lead to hepatocellular carcinoma. There are many factors influencing NAFLD initiation and progression, such as obesity, dyslipidemia, insulin resistance, genetic factors, and hormonal changes. However, there is also lean-NAFLD which is not associated with obesity. NAFLD is considered to be a sexually dimorphic disease. In most cases, men have a higher prevalence for the disease compared to premenopausal women. Areas covered: In this review, we first summarize the NAFLD disease epidemiology, pathology, and diagnosis. We describe NAFLD progression with the focus on sexual and genetic differences for disease development and pharmacological treatment. Personalized treatment for multifactorial NAFLD is discussed in consideration of different factors, including genetics, gender and sex. Expert opinion: The livers of female and male NAFLD patients have different metabolic capacities which influence the metabolism of all drugs applied to such patients. This aspect is not yet sufficiently taken into account. The liver computational models might quicken the pace toward assessing personalized disease progression and treatment options.

Daily cycle in hepatic lipid metabolism in obese mice, Neotomodon alstoni: Sex differences

Disruption of circadian rhythms influences the pathogenesis of obesity, particularly with the basic regulation of food intake and metabolism. A link between metabolism and the circadian clock is the peroxisome proliferator-activated receptors (PPARs). The Neotomodon alstoni mouse, known as the "Mexican volcano mouse," may develop obesity if fed a normo-caloric diet. This manuscript documents the changes in part of the hepatic lipid homeostasis in both sexes of lean and obese N. alstoni mice, comparing the daily changes in the BMAL1 clock protein, in regulators of lipid metabolism (PGC-1α, PPARα-γ, SREBP-1c, and CPT-1α) and in free fatty acid (FFA) and hepatic triacylglyceride (TAG) metabolites in light-dark cycles. Hepatic tissue and blood were collected at 5, 10, 15, 19, and 24 h. Samples were analyzed by western blotting to determine the relative presence of protein. The results indicate that obesity affects daily changes in lipid metabolism and the BMAL1 profile in females considerably more than in males. These results suggest that the impact of obesity on lipid metabolism has important differences according to sex.

Estrogen, estrogen receptors, and hepatocellular carcinoma: Are we there yet?

A protective role of the sex steroid hormone estrogen in hepatocellular carcinoma (HCC) was suggested a few decades ago according to clinical data showing higher HCC morbidity and mortality among males. Several recent studies further confirmed the anti-cancer effects of estrogen in the liver. However, it remains to be identified how to exploit estrogen signalling within clinical settings for HCC treatment. There are several unresolved issues related to the estrogen pathway in liver cells. The main problems include the absence of a clear understanding of which estrogen receptor (ER) isoform is predominantly expressed in normal and malignant liver cells, the ER isoform expression difference between males and females, and which ER isoform should be targeted when designing HCC therapy. Some of those questions were recently addressed by Iyer and co-authors. The current editorial review critically analyses the study by Iyer et al (WJG, 2017) that investigated the expression of ER subtypes in liver samples collected from patients with a healthy liver, hepatitis C virus cirrhosis, and HCC. ER presence was evaluated in association with gender, intracellular localization, inflammation marker NF-κB, and proliferation-related effector cyclin D1. The study limitations and advantages are discussed in light of recent advances in the HCC and estrogen signalling areas.