Sexual dimorphism in the content of progesterone and estrogen receptors, and their cofactors in the lung of adult rats

Roles of steroid receptors in the lung and COVID-19

COVID-19 symptoms and mortality are largely due to its devastating effects in the lungs. The disease is caused by the SARS (Severe Acute Respiratory Syndrome)-CoV-2 coronavirus, which requires host cell proteins such as ACE2 (angiotensin-converting enzyme 2) and TMPRSS2 (transmembrane serine protease 2) for infection of lung epithelia. The expression and function of the steroid hormone receptor family is important in many aspects that impact on COVID-19 effects in the lung - notably lung development and function, the immune system, and expression of TMPRSS2 and ACE2. This review provides a brief summary of current knowledge on the roles of the steroid hormone receptors [androgen receptor (AR), glucocorticoid receptor (GR), progesterone receptor (PR), mineralocorticoid receptor (MR) and oestrogen receptor (ER)] in the lung, their effects on host cell proteins that facilitate SARS-CoV-2 uptake, and provides a snapshot of current clinical trials investigating the use of steroid receptor (SR) ligands to treat COVID-19.

Sex Differences in Immunometabolism: An Unexplored Area

The last three decades have seen a growing interest in research in the field of immunometabolism, likely because of promising discoveries made in this field. This includes demonstration of the crucial roles of cellular metabolism in the regulation of functional plasticity of various immune cells, their cross talk with major metabolic tissues (and consequently in the regulation of metabolic homeostasis) at the systemic level, and their potential in improving the efficacy of current immunotherapy or developing new therapeutics for a variety of metabolic and immune diseases (Lee YS, Wollam J, Olefsky JM, Cell 172:22-40, 2018). Surprisingly, sex differences, which are integral to metabolic and immune health and disease, have received a short shrift from researchers in this field. The purpose of this chapter in this protocols book in the Immunometabolism: Methods in Molecular Biology series is to bring attention to this understudied, but crucial, feature of immunometabolism within the scientific community. Sex differences in adipose (and by extension, metabolic) and immune functions are pervasive in metabolic and immune health and disease; it is likely that a better insight into them may open new research directions to better capitalize on the promising discoveries made in this field, and thereby contribute to the development of sex-based precision medicine. It is counterintuitive to ignore a fundamental aspect of immunometabolism, and thereby limit our ability to capitalize on its promising features in improving or maintaining health, and for the therapeutic targeting of associated diseases. Here we briefly discuss the potential drivers and touch upon some unanswered questions in sex differences in immunometabolism, especially those that require attention from the scientific community.

Sex-specific effects of sex steroids on alveolar epithelial Na+ transport

Alveolar fluid clearance mediates perinatal lung transition to air breathing in newborn infants, which is accomplished by epithelial Na⁺ channels (ENaC) and Na-K-ATPase. Male sex represents a major risk factor for developing respiratory distress, especially in preterm infants. We previously showed that male sex is associated with reduced epithelial Na⁺ transport, possibly contributing to the sexual dimorphism in newborn respiratory distress. This study aimed to determine sex-specific effects of sex steroids on epithelial Na⁺ transport. The effects of testosterone, 5α-dihydrotestosterone (DHT), estradiol, and progesterone on Na⁺ transport and Na⁺ channel expression were determined in fetal distal lung epithelial (FDLE) cells of male and female rat fetuses by Ussing chamber and mRNA expression analyses. DHT showed a minor effect only in male FDLE cells by decreasing epithelial Na⁺ transport. However, flutamide, an androgen receptor antagonist, did not abolish the gender imbalance, and testosterone lacked any effect on Na⁺ transport in male and female FDLE cells. In contrast, estradiol and progesterone increased Na⁺ transport and Na⁺ channel expression especially in females, and prevented the inhibiting effect of DHT in males. Estrogen receptor inhibition decreased Na⁺ channel expression and eliminated the sex differences. In conclusion, female sex steroids stimulate Na⁺ transport especially in females and prevent the inhibitory effect of DHT in males. The ineffectiveness of testosterone suggests that Na⁺ transport is largely unaffected by androgens. Thus, the higher responsiveness of female cells to female sex steroids explains the higher Na⁺ transport activity, possibly leading to a functional advantage in females.

Sexual Dimorphism in the Regulation of Estrogen, Progesterone, and Androgen Receptors by Sex Steroids in the Rat Airway Smooth Muscle Cells

The role of sex hormones in lung is known. The three main sex steroid receptors, estrogen, progesterone, and androgen, have not been sufficiently studied in airway smooth muscle cells (ASMC), and the sex hormone regulation on these receptors is unknown. We examined the presence and regulation of sex hormone receptors in female and male rat ASMC by Western blotting and flow cytometry. Gonadectomized rats were treated with 17β-estradiol, progesterone, 17β-estradiol + progesterone, or testosterone. ASMC were enzymatically isolated from tracheas and bronchi. The experiments were performed with double staining flow cytometry (anti-α-actin smooth muscle and antibodies to each hormone receptor). ERα, ERβ, tPR, and AR were detected in females or males. ERα was upregulated by E2 and T and downregulated by P4 in females; in males, ERα was downregulated by P4, E + P, and T. ERβ was downregulated by each treatment in females, and only by E + P and T in males. tPR was downregulated by P4, E + P, and T in females. No hormonal regulation was observed in male receptors. AR was downregulated in males treated with E + P and T. We have shown the occurrence of sex hormone receptors in ASMC and their regulation by the sex hormones in female and male rats.

Male Sex is Associated with a Reduced Alveolar Epithelial Sodium Transport

Respiratory distress syndrome (RDS) is the most frequent pulmonary complication in preterm infants. RDS incidence differs between genders, which has been called the male disadvantage. Besides maturation of the surfactant system, Na⁺ transport driven alveolar fluid clearance is crucial for the prevention of RDS. Na⁺ transport is mediated by the epithelial Na⁺ channel (ENaC) and the Na,K-ATPase, therefore potential differences in their expression or activity possibly contribute to the gender imbalance observed in RDS. Fetal distal lung epithelial (FDLE) cells of rat fetuses were separated by sex and analyzed regarding expression and activity of the Na⁺ transporters. Ussing chamber experiments showed a higher baseline short-circuit current (I_SC) and amiloride-sensitive ΔI_SC in FDLE cells of female origin. In addition, maximal amiloride-sensitive ΔI_SC and maximal ouabain-sensitive ΔI_SC of female cells were higher when measured in the presence of a permeabilized basolateral or apical membrane, respectively. The number of FDLE cells per fetus recoverable during cell isolation was also significantly higher in females. In addition, lung wet-to-dry weight ratio was lower in fetal and newborn female pups. Female derived FDLE cells had higher mRNA levels of the ENaC- and Na,K-ATPase subunits. Furthermore, estrogen (ER) and progesterone receptor (PR) mRNA levels were higher in female cells, which might render female cells more responsive, while concentrations of placenta-derived sex steroids do not differ between both genders during fetal life. Inhibition of ER-β abolished the sex differences in Na⁺ transport and female cells were more responsive to estradiol stimulation. In conclusion, a higher alveolar Na⁺ transport, possibly attributable to a higher expression of hormone receptors in female FDLE cells, provides an explanation for the well known sex-related difference in RDS occurrence and outcome.

Sex dependent regulation of osteoblast response to implant surface properties by systemic hormones

Background

Osseointegration depends on the implant surface, bone quality and the local and systemic host environment, which can differ in male and female patients. This study was undertaken in order to determine if male and female cells respond differently to titanium surfaces that have micron-scale roughness and if interactions of calciotropic hormones [1α,25(OH)₂D₃ and 17β-oestradiol (E₂)] and microstructured surfaces on osteoblasts are sex dependent.

Methods

Osteoblasts from 6-week old Sprague-Dawley rats were cultured on tissue culture polystyrene (TCPS) or on titanium (Ti) disks with two different surface topographies, a smooth pretreated (PT) surface and a coarse grit-blasted/acid-etched (SLA) surface, and treated with 1α,25(OH)₂D₃, E₂, or E₂ conjugated to bovine serum albumin (E₂-BSA).

Results

Male and female cells responded similarly to Ti microstructure with respect to cell number and levels of osteocalcin, transforming growth factor-β1, osteoprotegerin and prostaglandin E₂ in their conditioned media, exhibiting a more differentiated phenotype on SLA than on PT or TCPS. E₂ and E₂-BSA increased differentiation and local factor production, an effect that was microstructure dependent and found only in female osteoblasts. 1α,25(OH)₂D₃ increased osteoblast differentiation and local factor production in female and male cells, but the effect was more robust in male cells.

Conclusions

Male and female rat osteoblasts respond similarly to surface microstructure but exhibit sexual dimorphism in substrate-dependent responses to systemic hormones. Oestrogen affected only female cells while 1α,25(OH)₂D₃ had a greater effect on male cells. These results suggest that successful osseointegration in males and females may depend on the implant surface design and correct levels of calciotropic hormones.

Progesterone induces scolex evagination of the human parasite Taenia solium: evolutionary implications to the host-parasite relationship

Taenia solium cysticercosis is a health problem in underdeveloped and developed countries. Sex hormones are involved in cysticercosis prevalence in female and male pigs. Here, we evaluated the effects of progesterone and its antagonist RU486 on scolex evagination, which is the initial step in the development of the adult worm. Interestingly, progesterone increased T. solium scolex evagination and worm growth, in a concentration-independent pattern. Progesterone effects could be mediated by a novel T. solium progesterone receptor (TsPR), since RU486 inhibits both scolex evagination and worm development induced by progesterone. Using RT-PCR and western blot, sequences related to progesterone receptor were detected in the parasite. A phylogenetic analysis reveals that TsPR is highly related to fish and amphibian progesterone receptors, whereas it has a distant relation with birds and mammals. Conclusively, progesterone directly acts upon T. solium cysticerci, possibly through its binding to a progesterone receptor synthesized by the parasite.

Activity and intracellular location of estrogen receptors alpha and beta in human bronchial epithelial cells

Gender differences in lung disease and cancer are well-established. We reported estrogenic transcriptional responses in lung adenocarcinoma cells from females but not males despite similar estrogen receptor (ER) expression. Here we tested the hypothesis that normal human bronchial epithelial cells (HBECs) show gender-independent estrogenic responses. We report that a small sample of HBECs express approximately twice as much ERbeta as ERalpha. ERalpha and ERbeta were located in the cytoplasm, nucleus, and mitochondria. In contrast to lung adenocarcinoma cells, estradiol (E2) induced estrogen response element (ERE)-mediated luciferase reporter activity in transiently transfected HBECs regardless of donor gender. Overexpression of ERalpha-VP16 increased ERE-mediated transcriptional activity in all HBECs. E2 increased and 4-hydroxytamoxifen and ICI 182,780 inhibited HBEC proliferation and cyclin D1 expression in a cell line-specific manner. In conclusion, the response of HBECs to ER ligands is gender-independent suggesting that estrogenic sensitivity may be acquired during lung carcinogenesis.

Sex steroidal hormones and respiratory control

There is a growing public awareness that sex hormones can have an impact on a variety of physiological processes. Yet, despite almost a century of research, we still do not have a clear picture as to the effects of sex hormones on the regulation of breathing. Considerable data has accumulated showing that estrogen, progesterone and testosterone can influence respiratory function in animals and humans. Several disorders of breathing such as obstructive sleep apnea (OSA) and sudden infant death syndrome (SIDS) show clear sex differences in their prevalence, lending weight to the importance of sex hormones in respiratory control. This review focuses on questions such as: how early do sex hormones influence breathing? Which is the most effective? Where do sex hormones exert their effects? What mechanisms are involved? Are there age-associated changes? A clearer understanding of how sex hormones influence the control of breathing could enable sex- and age-specific therapeutic interventions for diseases of the respiratory control system.

Targeting aromatase and estrogen signaling in human non-small cell lung cancer

Lung cancer has become increasingly common in women, and gender differences in the physiology and pathogenesis of the disease have suggested a role for estrogens. In the lung recent data have shown local production of estrogens from androgens via the action of aromatase enzyme and higher levels of estrogen in tumor tissue as compared with surrounding normal lung tissue. High levels of aromatase expression are also maintained in metastases as compared with primary tumors. Consistent with these findings, clinical studies suggest that aromatase expression may be a useful predictive biomarker for prognosis in the management of non-small cell lung cancer (NSCLC), the most common form of lung malignancy. Low levels of aromatase associate with a higher probability of long-term survival in older women with early stage NSCLC. Treatment of lung NSCLC xenografts in vivo with an aromatase inhibitor (exemestane) alone or combined with standard cisplatin chemotherapy elicits a significant reduction in tumor progression as compared to paired controls. Further, lung cancer progression is also governed by complex interactions between estrogen and growth factor signaling pathways to stimulate the growth of NSCLC as well as tumor-associated angiogenesis. We find that combination therapy with the multitargeted growth factor receptor inhibitor vandetanib and the estrogen receptor antagonist fulvestrant inhibit tumor growth more effectively than either treatment administered alone. Thus, incorporation of antiestrogen treatment strategies in standard antitumor therapies for NSCLC may contribute to improved patient outcome, an approach that deserves to be tested in clinical trials.

Estrous cycle alters naphthalene metabolism in female mouse airways

Previous studies have shown variability in naphthalene cytotoxicity, expression of CYP2F2 gene and protein, and naphthalene metabolism in random cycling female mice (NIH:Swiss). CYP2F2 metabolizes naphthalene to cytotoxic metabolites in lungs of mice. This study was designed to address the question: do hormonal changes associated with the estrous cycle alter metabolism of naphthalene in the lung? Adult virgin female mice were manipulated into defined stages of the reproductive cycle: estrus, proestrus, and noncycling. Cycling was confirmed by cytology on vaginal swabs. At specific cycle times, extrapulmonary (tracheal and bronchial) and intrapulmonary (bronchiolar) conducting airways were microdissected from the lung parenchyma and incubated with naphthalene, and the products of naphthalene metabolism were trapped and measured using high-performance liquid chromatography. Circulating estradiol levels were measured at necropsy using an enzyme-linked immunosorbent assay. CYP2F2 gene expression was determined by airway level using real-time reverse transcription-polymerase chain reaction and did not vary by estrous cycle stage in intrapulmonary airways but did in extrapulmonary airways. Metabolism of naphthalene varied significantly by estrous cycle stage with the highest level of total metabolism occurring in proestrus (when estrogen is lowest) in intrapulmonary airways. Total activity and metabolite profiles in both extrapulmonary and intrapulmonary airways were affected by cycle stage. We conclude that the hormonal patterns associated with different stages of the estrous cycle 1) alter metabolism of naphthalene in the lungs of mice and 2) alter naphthalene metabolism differentially in extrapulmonary versus intrapulmonary airways.

Changes in the content of steroid receptor coactivator-1 and silencing mediator for retinoid and thyroid hormone receptors in the rat brain during the estrous cycle

In this work, we determined the variations in the content of the steroid receptor coactivator (SRC-1) and the silencing mediator for retinoic acid and thyroid hormone receptors corepressor (SMRT) in the hypothalamus, the preoptic area, and the hippocampus of adult intact rats during the estrous cycle by Western blot. SRC-1 content changed only in the hypothalamus where its lowest content was found on diestrus day with a significant increase at proestrus. This increase was maintained on estrus day. In contrast, SMRT content changed only in the preoptic area where it diminished at metestrus in comparison with the other days of the cycle. SRC-1 content was higher than that of SMRT in the hypothalamus throughout the estrous cycle, whereas SMRT content was higher in the preoptic area. In the hippocampus, there were no significant differences in the content of any cofactor. These results demonstrate that SRC-1 and SMRT content change in a tissue-specific manner in the rat brain during the estrous cycle, and suggest that the transcriptional activity of steroid hormone receptors in the rat brain in physiological conditions is regulated by changes in SRC-1 and SMRT content.