Sex steroid signaling: implications for lung diseases

Intracrine Regulation of Estrogen and Other Sex Steroid Levels in Endometrium and Non-gynecological Tissues; Pathology, Physiology, and Drug Discovery

Our understanding of the intracrine (or local) regulation of estrogen and other steroid synthesis and degradation expanded in the last decades, also thanks to recent technological advances in chromatography mass-spectrometry. Estrogen responsive tissues and organs are not passive receivers of the pool of steroids present in the blood but they can actively modify the intra-tissue steroid concentrations. This allows fine-tuning the exposure of responsive tissues and organs to estrogens and other steroids in order to best respond to the physiological needs of each specific organ. Deviations in such intracrine control can lead to unbalanced steroid hormone exposure and disturbances. Through a systematic bibliographic search on the expression of the intracrine enzymes in various tissues, this review gives an up-to-date view of the intracrine estrogen metabolisms, and to a lesser extent that of progestogens and androgens, in the lower female genital tract, including the physiological control of endometrial functions, receptivity, menopausal status and related pathological conditions. An overview of the intracrine regulation in extra gynecological tissues such as the lungs, gastrointestinal tract, brain, colon and bone is given. Current therapeutic approaches aimed at interfering with these metabolisms and future perspectives are discussed.

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

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

Sex differences in respiratory function

Men Are from Mars, Women Are from Venus. John Gray used this provocative title for his book to describe the fundamental psychological differences between the sexes. Many other controlled studies and brain scans demonstrate that men and women are physically and mentally different. The purpose of this physiology masterclass is to illustrate how sex-related differences are present in respiratory function and their possible clinical implications.

An overview of sex-related differences in respiratory function and their possible clinical implicationshttp://ow.ly/106m30jqOSW

Gender differences in bronchiectasis: a real issue?

Gender differences in chronic respiratory disease, including cystic fibrosis and non-cystic fibrosis bronchiectasis are clinically apparent and of increasing importance. Differences in disease prevalence, severity and outcome are all described, however, the precise cause of the gender dichotomy and their associated underlying mechanisms have been poorly characterised. A lack of dedicated clinical and epidemiological research focused in this area has led to a paucity of data and therefore a lack of understanding of its key drivers. Diagnosis, disease pathogenesis and treatment response are all complex but important aspects of bronchiectasis with an evident gender bias. Broadening our understanding of the interplay between microbiology, host physiology and the environment in the context of chronic lung diseases, such as bronchiectasis, is critical to unravelling mechanisms driving the observed gender differences. In this review, epidemiological, biological and environmental evidence related to gender in bronchiectasis is summarised. This illustrates gender differences as a “real issue” with the objective of mapping out a future framework upon which a gender-tailored medical approach may be incorporated into the diagnosis, monitoring and treatment of bronchiectasis.

CF and non-CF bronchiectasis are complex multifactorial chronic pulmonary diseases demonstrating gender differences in their prevalence, severity and infections, some of which are attributable to sex hormoneshttp://ow.ly/beDf30jseK4

Sex differences in sleep apnea and comorbid neurodegenerative diseases

Sleep apnea is a disorder, which increasingly affects people worldwide. Whether the associated hypoxic events during sleep are central or obstructive in origin, the end result is excessive daytime sleepiness and an increased risk for several comorbidities, such as cardiovascular and neurodegenerative disorders. Sleep apnea is diagnosed more frequently in men than women, suggesting a role of sex hormones in the pathology of the disease. Furthermore, there are sex differences in the development and progression of comorbid diseases associated with sleep apnea. Therefore, treatment of sleep apnea may be clinically relevant for prevention of subsequent sex-specific comorbid disorders. While the impact sleep apnea has on cardiovascular events has been the subject of many research studies, the role of sleep apnea in neurodegeneration is less established. Here we review known risk factors for sleep apnea and the implications of the observed sex differences in this disease. We also summarize the evidence and mechanisms for how sleep apnea may contribute to the onset of neurodegenerative disorders, such as Alzheimer's disease and Parkinson's disease.

Studying allergic inflammation and spirometry over menstrual cycles in well-controlled asthmatic women: Changes in progesterone and estradiol affect neither FENO levels nor lung function

It has been reported that female sex hormones influence on allergic inflammation and ventilation parameters in asthma but conclusions drawn by different researchers are divergent. The aim of our study was to assess the impact of progesterone (Pg) and estradiol (E) on the dynamics of allergic inflammation and spirometry test results in regularly menstruating women with stable allergic asthma. 13 women (28 days menstrual cycle), aged 18-45, taking no hormonal contraceptives, with mild and moderate asthma, without reported exacerbations at the near-ovulation and/or menstruation time, were monitored during two consecutive menstrual cycles. They had 4 visits per cycle (the first day of menstruation was assumed to be day 1 of the cycle; visits were carried out on days: 3-4, 10-11, 13-14 and 23-24). At each visit asthma symptoms, asthma control test (ACT) results, asthma treatment, fractioned nitric oxide (FENO) levels, spirometry test results, Pg and E, levels were analyzed. As a result of the study, no essential variability in FENO values and ventilation parameters' values in the course of menstruation cycle were observed. Negative correlation between FENO values and Pg concentrations was demonstrated (r = 0.27), but no correlation between FENO values and E levels was shown. No relationship between the ACT values and ventilation parameters and the levels of the sex hormones under investigation was detected. We conclude that changing levels of estradiol and progesterone (regardless of the negative correlation of progesterone and FENO values) affect neither the dynamics of allergic inflammation nor pulmonary function in women with stable allergic mild/moderate asthma.

Hormonal Smartphone Diagnostics

Mobile point-of-care diagnostics are paramount for the provision of healthcare. Hormonal diagnostics are powerful tools to monitor timely changes in human physiology. Hormone concentrations in serum directly correlate with urine excretions with minor time delays. Therefore, rapid tests for hormones in urine have been widely used for decades as means of early diagnostics, particularly in lateral flow immunoassay formats. However, the challenge of reading and interpreting these binary tests remains. Here we present a method for utilizing mobile technologies to quantitatively read and interpret hormonal test strips. The method demonstrates the detection of a urinary by-product of progesterone, pregnanediol glucuronide (PdG), and its relation to ovulation and the fertility cycle.

Gender aspects and influence of hormones on bronchial asthma - Secondary publication and update

There is good evidence for gender-specific differences in asthma regarding all affected areas, from intra- to extra-cellular mediators to the whole organ structure und functioning of the lung. These result from complex, in parts synergistic, in other parts opposing, effects - especially of female sex hormones, and rather protective effects of male hormones against asthma, which include effects on the cellular immune system. Additionally, there are gender differences of sociocultural origin, regarding presentation, doctor's diagnosis and treatment of asthma symptoms, as well as the undertaken coping strategies concerning the female or male patient's complaints. Taking into account gender-specific differences in asthma would contribute to improved individual diagnosis and therapies.

Arginase 1 deletion in myeloid cells affects the inflammatory response in allergic asthma, but not lung mechanics, in female mice

BACKGROUND

(Over-)expression of arginase may limit local availability of arginine for nitric oxide synthesis. We investigated the significance of arginase1 (ARG1) for the development of airway hyperresponsiveness (AHR) and lung inflammation in female mice with ovalbumin (OVA)-induced allergic asthma.

METHODS

Arg1 was ablated in the lung by crossing Arg1 fl/fl and Tie2Cre tg/- mice. OVA sensitization and challenge were conducted, and AHR to methacholine was determined using the Flexivent system. Changes in gene expression, chemokine and cytokine secretion, plasma IgE, and lung histology were quantified using RT-qPCR, ELISA, and immunohistochemistry, respectively.

RESULTS

Arg1 ablation had no influence on the development of OVA-induced AHR, but attenuated OVA-induced increases in expression of Arg2 and Nos2, Slc7a1, Slc7a2, and Slc7a7 (arginine transporters), Il4, Il5 and Il13 (TH2-type cytokines), Ccl2 and Ccl11 (chemokines), Ifng (TH1-type cytokine), Clca3 and Muc5ac (goblet cell markers), and OVA-specific IgE. Pulmonary IL-10 protein content increased, but IL-4, IL-5, IL-13, TNFα and IFNγ content, and lung histopathology, were not affected. Arg1 elimination also decreased number and tightness of correlations between adaptive changes in lung function and inflammatory parameters in OVA/OVA-treated female mice. OVA/OVA-treated female mice mounted a higher OVA-IgE response than males, but the correlation between lung function and inflammation was lower. Arg1-deficient OVA/OVA-treated females differed from males in a more pronounced decline of arginine-metabolizing and -transporting genes, higher plasma arginine levels, a smaller OVA-specific IgE response, and no improvement of peripheral lung function.

CONCLUSION

Complete ablation of Arg1 in the lung affects mRNA abundance of arginine-transporting and -metabolizing genes, and pro-inflammatory genes, but not methacholine responsiveness or accumulation of inflammatory cells.

Different inhibitory potential of sex hormones on NNK detoxification in vitro: A possible explanation for gender-specific lung cancer risk

Smoking women are probably at a higher risk to develop lung cancer than men. Different explanations exist for these findings, a gender-specific impairment of tobacco carcinogen metabolism being one of them. In this study, we examined the inhibition of NNK reduction to NNAL, the first and most important detoxication step of this tobacco-specific carcinogen. It is mediated by different carbonyl reductases of the SDR (CBR1 and 11βHSD1) and AKR (AKR1B10, AKR1C1, AKR1C2 and AKR1C4) superfamilies. Inhibition constants of NNK reduction were determined with male (testosterone) and female (estradiol, progesterone) sex hormones and the contraceptives ethinylestradiol and drospirenone in A549 cells and with purified enzymes. Female sex hormones turned out to be stronger inhibitors than testosterone. The gestagen progesterone and its synthetic derivative drospirenone are the strongest inhibitors with Ki-values similar to hormone levels in pregnant women or women using hormonal contraceptives. Therefore, pregnancy or hormonal contraception may commit these women as high risk groups. The results of this study support the hypothesis that women bear a higher lung cancer risk when smoking because of female sex hormones acting as inhibitors of NNK detoxication.

Neonatal rat age, sex and strain modify acute antioxidant response to ozone

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death in the US and its impact continues to increase in women. Oxidant insults during critical periods of early life appear to increase risk of COPD through-out the life course. To better understand susceptibility to early life exposure to oxidant air pollutants we used Fisher (F344), Sprague-Dawley (SD) and Wistar (WIS) male and female neonatal rat pups to assess: (A) if strain (i.e. genetics), sex, or stage of early life development affected baseline lung antioxidant or redox enzyme levels and (B) if these same factors modulated antioxidant responsiveness to acute ozone exposure (1 ppm × 2 h) on post-natal day (PND) 14, 21, or 28. In air-exposed pups from PND14-28, some parameters were unchanged (e.g. uric acid), some decreased (e.g. superoxide dismutase), while others increased (e.g. glutathione recycling enzymes) especially post-weaning. Lung total glutathione levels decreased in F344 and SD pups, but were relatively unchanged in WIS pups. Post-ozone exposure, data suggest that: (1) the youngest (PND14) pups were the most adversely affected; (2) neonatal SD and WIS pups, especially females, were more prone to ozone effects than males of the same age and (3) F344 neonates (females and males) were less susceptible to oxidative lung insult, not unlike F344 adults. Differences in antioxidant levels and responsiveness between sexes and strains and at different periods of development may provide a basis for assessing later life health outcomes - with implications for humans with analogous genetic or dietary-based lung antioxidant deficits.

Higher prevalence of clinical cardiovascular comorbidities in postmenopausal women with self-reported premenopausal hirsutism and/or oligo-amenorrhea

Hirsutism is a common condition, being present in about 5–15% of women. It is characterized by the growth of terminal hair in a pattern typical for men, like as hair growth in upper lip, chin, cheek and lower and upper abdomen. Not infrequently, hirsutism is followed by other signs of hyerandrogenism such as alopecia, acne, and seborrhea. The current study evaluated the association between a self-reported history of hirsutism and oligo-amenorrhea during reproductive age and the presence of several comorbidities in women after menopause. A total of 1057 women were investigated in a cross-sectional study, and information on the age at menarche, menstrual history, complaints about excessive hair growth, and disease development was obtained. Participants from the study were postmenopausal women aged >55 y who attended ac primary care service at least once during the 24-month period. Exclusion criteria included the presence of cognitive impairment and/or communication difficulties. Main outcomes were the presence of comorbidities after menopause. The prevalence of comorbidities was significantly higher in women with a history of hirsutism and/or oligo-amenorrhea [OR = 1.6 (95% CI 1.1–2.4), p = 0.002] or isolated hirsutism [OR 2.0 (95% CI 1.3–3.2), p = 0.004]. The prevalence of stroke, angina or myocardial infarction, cardiac failure, chronic obstructive pulmonary disease, and osteoarthritis were significantly higher in postmenopausal women who had experienced hirsutism and/or oligomenorrhea (p < 0.03). Limitations of the study came from the absence of a clear differentiation between hirsutism and hypertrichosis. According our results, the presence of hirsutism and oligo-amenorrhea during the female reproductive period may indicate susceptibility to important diseases at old age.

Menstrual and reproductive factors and lung cancer risk: A pooled analysis from the international lung cancer consortium

Many clinical features of lung cancer are different in women and men. Sex steroid hormones exert effects in nonreproductive organs, such as the lungs. The association between menstrual and childbearing factors and the risk of lung cancer among women is still debated. We performed a pooled analysis of eight studies contributing to the International Lung Cancer Consortium (4,386 cases and 4,177 controls). Pooled associations between menstrual or reproductive factors and lung cancer were estimated using multivariable unconditional logistic regression. Subgroup analyses were done for menopause status, smoking habits and histology. We found no strong support for an association of age at menarche and at menopause with lung cancer, but peri/postmenopausal women were at higher risk compared to premenopausal (OR 1.47, 95% CI 1.11-1.93). Premenopausal women showed increased risks associated with parity (OR 1.74, 95% CI 1.03-2.93) and number of children (OR 2.88, 95% CI 1.21-6.93 for more than 3 children; p for trend 0.01) and decreased with breastfeeding (OR 0.54, 95% CI 0.30-0.98). In contrast, peri/postmenopausal subjects had ORs around unity for the same exposures. No major effect modification was exerted by smoking status or cancer histology. Menstrual and reproductive factors may play a role in the genesis of lung cancer, yet the mechanisms are unclear, and smoking remains the most important modifiable risk factor. More investigations in large well-designed studies are needed to confirm these findings and to clarify the underlying mechanisms of gender differences in lung cancer risk.

Women Epidemiology Lung Cancer (WELCA) study: reproductive, hormonal, occupational risk factors and biobank

Background

Lung cancer aetiology and clinical aspects have been mainly studied in men, although specific risk factors probably exist in women. Here we present the rationale, design and organization of the WELCA study (Women Epidemiology Lung CAncer) that has been launched to investigate lung cancer in women, focusing particularly on hormonal and occupational factors.

Methods/Design

WELCA is a population based case-control study and planned to recruit 1000 cases and 1000 controls in three years, based on study power calculation. Eligible cases are female patients newly diagnosed with lung cancer, living in Paris and the Ile de France area and aged up to 75 years. Almost all Parisian pneumology and oncology clinical departments are involved. The control group is a random sample of the population living in the same area, frequency-matched on age and additionally stratified on the distribution of socio-professional categories of women residing there. After acquisition of written consent, research nurses administer standardized computer assisted questionnaires to all the subjects in face-to-face interviews and acquire anthropometric measures. Besides usual socio-demographic characteristics, information is gathered about menstrual and reproductive factors, hormonal treatments, lifestyle and leisure characteristics, occupational history, personal and familial medical history. Biological samples are also collected, in order to establish a biobank for molecular epidemiology studies. Molecular characteristics of the tumours will be obtained and patients will be followed up for five years.

Discussion

The WELCA study aims to answer key questions in lung cancer aetiology and clinical characteristics specifically in women. The role of hormonal impregnation is investigated, and the interactions with cigarette smoking or body mass index (BMI) will be analyzed in detail. The occupational history of the subjects is carefully reconstructed, focusing in particular on the service sector. The creation of a biobank for collection of serum, plasma, DNA and tumour tissue will allow the genetic and biochemical characterization of both the subjets and the tumours. The follow-up of the patients will help in disentangling the role of hormonal factors and tumour molecular characteristics in survival.

Increased levels of enzymes involved in local estradiol synthesis in chronic obstructive pulmonary disease

INTRODUCTION

Steroid hormones are involved in lung development, pulmonary inflammation, and lung cancer. Estrogen signaling and exposure may play a role in pulmonary disorders, including COPD. In both genders, estrogens can be generated locally in the lungs and this contributes importantly to the tissue exposure to these steroids.

OBJECTIVE

To characterize and assess differences in localization of estrogen receptors and enzymes involved in the local generation of estrogens in COPD.

METHODS

Estrogen Receptor alpha (ERα/ESR1), Estrogen Receptor beta (ERβ/ESR2) and G-protein-coupled estrogen receptor 1 (GPER) were explored by real-time (RT)-PCR analysis (mRNA expression), immunohistochemistry and western blotting in controls and COPD patients. mRNA expression of the enzymes involved in the local estrogen generation - i.e. aromatase (CYP19A1), 17beta-hydroxysteroid dehydrogenases (17β-HSDs) 1, 2, 4, 5, 7 and 12, steroid sulfatase (STS) and sulfotransferase (SULT1E1) - were analyzed by RT-PCR.

RESULTS

ERα, ERβ and GPER were expressed in lung tissue, but no differences were observed between patients and controls. The main enzymes involved in local estrogen generation were also present in both normal and COPD lung tissue. In lungs of COPD patients compared with controls, we observed increased expression of the enzymes 17β-HSD type 1 and aromatase (positive association), both involved in the local synthesis of active estrogens.

CONCLUSION

All ER subtypes are present in the lung. The shift in local mRNA level of estrogen metabolic enzymes suggests that exposure to estrogens is involved in the pathogenesis of COPD.

Differential Expression of Estrogen Receptor Variants in Response to Inflammation Signals in Human Airway Smooth Muscle

The prevalence of asthma is higher in pre-pubescent and aging males, and in post-pubertal females, strongly indicating that sex steroids (especially estrogen) may be an important modulator in lung disease. We recently demonstrated that airway smooth muscle (ASM) expresses both alpha and beta forms of the estrogen receptor (ERα and ERβ) in males and females, and that these receptors regulate intracellular [Ca²⁺ ] and ASM contractility. Although both ERα and ERβ have multiple splice variants, it is unclear if and how the expression of these variants is modulated under conditions such as chronic inflammation/asthma. In order to test the hypothesis that the differential expression of ERα and ERβ variants contributes to the pathogenesis of asthma, we profiled the expression of various ERα and ERβ genes in asthmatic and inflamed (TNFα- or IL-13-treated) ASM. Gene expression was assessed at both the mRNA and protein levels in asthmatic ASM cells or non-asthmatic cells treated with TNFα (20 ng/ml) or IL-13 (50 ng/ml). We observed marked variation in the expression of ER isoforms in response to inflammatory stimuli, and in non-asthmatic versus asthmatic ASM. Changes in protein levels of ERα and ERβ corresponded with the observed differential mRNA patterns. Pharmacological studies implicate cytosolic (p42/44 MAPK and PI3 K) and nuclear (NFκB, STAT6, and AP-1) signaling pathways as putative mechanisms that mediate and/or regulate effects of inflammation on ER expression. We conclude that variations in ASM ER expression profiles occur with inflammation and that ER variants could contribute to estrogen signaling in airway diseases such as asthma. J. Cell. Physiol. 232: 1754-1760, 2017. © 2016 Wiley Periodicals, Inc.

Asthma in adolescence: Is there any news?

Asthma is a chronic disease that has a significant impact quality of life, which is particularly important in adolescence. We will discuss aspects of epidemiology, the clinical spectrum, diagnostics, and management of asthma in adolescence. In particular, we will highlight the psychological implications of having asthma during this developmental period. Data published in the past 10 years, since we last reviewed the subject, will be the main focus of this paper. The care of the teenager with asthma should take into account the rapid physical, emotional, cognitive, and social changes that occur during normal adolescence. The diagnostic process may be more difficult since teenagers tend to deny their illness. Thus, both under-diagnosis and under-assessment of asthma severity may lead to under-treatment and potentially avoidable morbidity and even mortality. Conversely, teenagers may be often misdiagnosed as having asthma or their asthma severity may be overestimated leading to inappropriate and sometimes excessive treatment. Educational programs, environmental avoidance measures, proper use of medications along with a skilled approach, and a caring attitude of health providers are all very important for successful management. Pediatr Pulmonol. 2017;52:129-138. © 2016 Wiley Periodicals, Inc.

Association between asthma and female sex hormones

CONTEXT AND OBJECTIVE:

The relationship between sex hormones and asthma has been evaluated in several studies. The aim of this review article was to investigate the association between asthma and female sex hormones, under different conditions (premenstrual asthma, use of oral contraceptives, menopause, hormone replacement therapy and pregnancy).

DESIGN AND SETTING:

Narrative review of the medical literature, Universidade Federal do Tocantins (UFT) and Universidade Federal de São Paulo (Unifesp).

METHODS:

We searched the CAPES journal portal, a Brazilian platform that provides access to articles in the MEDLINE, PubMed, SciELO, and LILACS databases. The following keywords were used based on Medical Subject Headings: asthma, sex hormones, women and use of oral contraceptives.

RESULTS:

The associations between sex hormones and asthma remain obscure. In adults, asthma is more common in women than in men. In addition, mortality due to asthma is significantly higher among females. The immune system is influenced by sex hormones: either because progesterone stimulates progesterone-induced blocking factor and Th2 cytokines or because contraceptives derived from progesterone and estrogen stimulate the transcription factor GATA-3.

CONCLUSIONS:

The associations between asthma and female sex hormones remain obscure. We speculate that estrogen fluctuations are responsible for asthma exacerbations that occur in women. Because of the anti-inflammatory action of estrogen, it decreases TNF-α production, interferon-γ expression and NK cell activity. We suggest that further studies that highlight the underlying physiopathological mechanisms contributing towards these interactions should be conducted.

Emerging concepts in smooth muscle contributions to airway structure and function: implications for health and disease

Airway structure and function are key aspects of normal lung development, growth, and aging, as well as of lung responses to the environment and the pathophysiology of important diseases such as asthma, chronic obstructive pulmonary disease, and fibrosis. In this regard, the contributions of airway smooth muscle (ASM) are both functional, in the context of airway contractility and relaxation, as well as synthetic, involving production and modulation of extracellular components, modulation of the local immune environment, cellular contribution to airway structure, and, finally, interactions with other airway cell types such as epithelium, fibroblasts, and nerves. These ASM contributions are now found to be critical in airway hyperresponsiveness and remodeling that occur in lung diseases. This review emphasizes established and recent discoveries that underline the central role of ASM and sets the stage for future research toward understanding how ASM plays a central role by being both upstream and downstream in the many interactive processes that determine airway structure and function in health and disease.

A potential role for estrogen in cigarette smoke-induced microRNA alterations and lung cancer

Alteration in the expression of microRNAs (miRNAs) is associated with oncogenesis and cancer progression. In this review we aim to suggest that elevated levels of estrogens and their metabolites inside the lungs as a result of cigarette smoke exposure can cause widespread repression of miRNA and contribute to lung tumor development. Anti-estrogenic compounds, such as the components of cruciferous vegetables, can attenuate this effect and potentially reduce the risk of lung cancer (LC) among smokers.

Androgen-metabolizing enzymes: A structural perspective

Androgen-metabolizing enzymes convert cholesterol, a relatively inert molecule, into some of the most potent chemical messengers in vertebrates. This conversion involves thermodynamically challenging reactions catalyzed by P450 enzymes and redox reactions catalyzed by Aldo-Keto Reductases (AKRs). This review covers the structures of these enzymes with a focus on active site interactions and proposed mechanisms. Due to their role in a number of diseases, particularly in cancer, androgen-metabolizing enzymes have been targets of drug design. Hence we will also highlight how existing knowledge of structure is being used to this end.

The effects of urban particulate matter on the nasal epithelium by gender: An experimental study in mice

Nose is the first portion of the respiratory system into contact with air pollution particles, including organic compounds that could act as endocrine releasers. The objective was to identify and quantify estrogenic receptor-β (ERβ), aryl hydrocarbon receptor (AhR), the cytochrome P450 enzymes CYP1A1, 1A2, 1B1, and mucus profile in the nasal epithelium of mice. BALB/c mice male (n = 32) and female (n = 82) in proestrus, estrus and diestrus were divided into two groups: 1) exposed to ambient air; 2) concentrated ambient particles (CAPs) to achieve an accumulated dose (concentration vs. time product) of 600 μg/m(3), the time of the exposure was controlled to ensure the same concentration for all groups (5 days per week for 40-51 days). RT-PCR (Erβ-1, Erβ-2, Ahr, Cyp1a1, Cyp1a2, Cyp1b1), immunohistochemistry and morphometry (ERβ, AhR) were used to analyze. The mucus profiles were examined using acid (Alcian Blue) and neutral (periodic acid Schiff's) stains. Exposed females had significantly lower levels of Erβ-2 mRNA than exposed males (p = 0.036). Cyp1b1 mRNA in diestrus females was significantly lower in the CAP-exposed group compared with the ambient air group (p ≤ 0.05). ERβ expression in the epithelium and submucosa nucleus was lower in estrus exposed to CAPs compared with ambient air. CAPs increases AhR in the epithelium (p = 0.044) and submucosa (p = 0.001) nucleus of female when compared with male mice. Exposure to CAPs, also led to relatively increased acidic content in the mucus of males (p = 0.048), but decreased acidic content in that of females (p = 0.04). This study revealed sex-dependent responses to air pollution in the nasal epithelium that may partially explain the predisposition of females to airway respiratory diseases.

Increasing awareness of sex differences in airway diseases

There is growing epidemiologic data demonstrating sex differences with respect to prevalence and progression of airway diseases, including asthma, chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF) and non-CF-related bronchiectasis. In asthma, for example, young boys have increased exacerbations and higher morbidity than girls which distinctly reverses after adolescence and into adulthood. In COPD, a disease that was historically considered an illness of men, the number of women dying per year is now greater than in men. Finally, women with CF-related bronchiectasis have a decreased median life expectancy relative to men and a higher risk of respiratory infections despite equal prevalence of the disease. A number of studies now exist demonstrating mechanisms behind these sex differences, including influences of genetic predisposition, sex hormones and comorbidities. The notable sex disparity has potential diagnostic, therapeutic and prognostic implications and for the practicing respiratory or general physician, a familiarity with these distinctions may augment effective management of patients with airway diseases. This review seeks to concisely summarize the data regarding gender-based differences in airway diseases, outline the current understanding of contributing factors and discuss therapeutic implications for clinicians.

Sex Steroids Influence Brain-Derived Neurotropic Factor Secretion From Human Airway Smooth Muscle Cells

Brain derived neurotropic factor (BDNF) is emerging as an important player in airway inflammation, remodeling, and hyperreactivity. Separately, there is increasing evidence that sex hormones contribute to pathophysiology in the lung. BDNF and sex steroid signaling are thought to be intricately linked in the brain. There is currently little information on BDNF and sex steroid interactions in the airway but is relevant to understanding growth factor signaling in the context of asthma in men versus women. In this study, we assessed the effect of sex steroids on BDNF expression and secretion in human airway smooth muscle (ASM). Human ASM was treated with estrogen (E2 ) or testosterone (T, 10 nM each) and intracellular BDNF and secreted BDNF measured. E2 and T significantly reduced secretion of BDNF; effects prevented by estrogen and androgen receptor inhibitor, ICI 182,780 (1 μM), and flutamide (10 μM), respectively. Interestingly, no significant changes were observed in intracellular BDNF mRNA or protein expression. High affinity BDNF receptor, TrkB, was not altered by E2 or T. E2 (but not T) significantly increased intracellular cyclic AMP levels. Notably, Epac1 and Epac2 expression were significantly reduced by E2 and T. Furthermore, SNARE complex protein SNAP25 was decreased. Overall, these novel data suggest that physiologically relevant concentrations of E2 or T inhibit BDNF secretion in human ASM, suggesting a potential interaction of sex steroids with BDNF in the airway that is different from brain. The relevance of sex steroid-BDNF interactions may lie in their overall contribution to airway diseases such as asthma.

Women and Lung Disease. Sex Differences and Global Health Disparities

There is growing evidence that a number of pulmonary diseases affect women differently and with a greater degree of severity than men. The causes for such sex disparity is the focus of this Blue Conference Perspective review, which explores basic cellular and molecular mechanisms, life stages, and clinical outcomes based on environmental, sociocultural, occupational, and infectious scenarios, as well as medical health beliefs. Owing to the breadth of issues related to women and lung disease, we present examples of both basic and clinical concepts that may be the cause for pulmonary disease disparity in women. These examples include those diseases that predominantly affect women, as well as the rising incidence among women for diseases traditionally occurring in men, such as chronic obstructive pulmonary disease. Sociocultural implications of pulmonary disease attributable to biomass burning and infectious diseases among women in low- to middle-income countries are reviewed, as are disparities in respiratory health among sexual minority women in high-income countries. The implications of the use of complementary and alternative medicine by women to influence respiratory disease are examined, and future directions for research on women and respiratory health are provided.