Testosterone induces hyporesponsiveness by interfering with IP3 receptors in guinea pig airway smooth muscle

Chamaecyparis lawsoniana and Its Active Compound Quercetin as Ca2+ Inhibitors in the Contraction of Airway Smooth Muscle

The Cupressaceae family includes species considered to be medicinal. Their essential oil is used for headaches, colds, cough, and bronchitis. Cedar trees like Chamaecyparis lawsoniana (C. lawsoniana) are commonly found in urban areas. We investigated whether C. lawsoniana exerts some of its effects by modifying airway smooth muscle (ASM) contractility. The leaves of C. lawsoniana (363 g) were pulverized mechanically, and extracts were obtained by successive maceration 1:10 (w:w) with methanol/CHCl3. Guinea pig tracheal rings were contracted with KCl, tetraethylammonium (TEA), histamine (HIS), or carbachol (Cch) in organ baths. In the Cch experiments, tissues were pre-incubated with D-600, an antagonist of L-type voltage-dependent Ca2+ channels (L-VDCC) before the addition of C. lawsoniana. Interestingly, at different concentrations, C. lawsoniana diminished the tracheal contractions induced by KCl, TEA, HIS, and Cch. In ASM cells, C. lawsoniana significantly diminished L-type Ca2+ currents. ASM cells stimulated with Cch produced a transient Ca2+ peak followed by a sustained plateau maintained by L-VDCC and store-operated Ca2+ channels (SOCC). C. lawsoniana almost abolished this last response. These results show that C. lawsoniana, and its active metabolite quercetin, relax the ASM by inhibiting the L-VDCC and SOCC; further studies must be performed to obtain the complete set of metabolites of the extract and study at length their pharmacological properties.

Estrogenic Modulation of Ionic Channels, Pumps and Exchangers in Airway Smooth Muscle

To preserve ionic homeostasis (primarily Ca²⁺, K⁺, Na⁺, and Cl^-), in the airway smooth muscle (ASM) numerous transporters (channels, exchangers, and pumps) regulate the influx and efflux of these ions. Many of intracellular processes depend on continuous ionic permeation, including exocytosis, contraction, metabolism, transcription, fecundation, proliferation, and apoptosis. These mechanisms are precisely regulated, for instance, through hormonal activity. The lipophilic nature of steroidal hormones allows their free transit into the cell where, in most cases, they occupy their cognate receptor to generate genomic actions. In the sense, estrogens can stimulate development, proliferation, migration, and survival of target cells, including in lung physiology. Non-genomic actions on the other hand do not imply estrogen's intracellular receptor occupation, nor do they initiate transcription and are mostly immediate to the stimulus. Among estrogen's non genomic responses regulation of calcium homeostasis and contraction and relaxation processes play paramount roles in ASM. On the other hand, disruption of calcium homeostasis has been closely associated with some ASM pathological mechanism. Thus, this paper intends to summarize the effects of estrogen on ionic handling proteins in ASM. The considerable diversity, range and power of estrogens regulates ionic homeostasis through genomic and non-genomic mechanisms.

Theophylline-Induced Relaxation Is Enhanced after Testosterone Treatment via Increased KV1.2 and KV1.5 Protein Expression in Guinea Pig Tracheal Smooth Muscle

Theophylline is a drug commonly used to treat asthma due to its anti-inflammatory and bronchodilatory properties. Testosterone (TES) has been suggested to reduce the severity of asthma symptoms. This condition affects boys more than girls in childhood, and this ratio reverses at puberty. We reported that guinea pig tracheal tissue chronic exposure to TES increases the expression of β₂-adrenoreceptors and enhances salbutamol-induced K⁺ currents (IK⁺). Herein, we investigated whether the upregulation of K⁺ channels can enhance the relaxation response to methylxanthines, including theophylline. Chronic incubation of guinea pig tracheas with TES (40 nM, 48 h) enhanced the relaxation induced by caffeine, isobutylmethylxanthine, and theophylline, an effect that was abolished by tetraethylammonium. In tracheal myocytes, chronic incubation with TES increased theophylline-induced IK⁺; flutamide reversed this effect. The increase in IK⁺ was blocked by 4-aminopyridine by ~82%, whereas iberiotoxin reduced IK⁺ by ~17%. Immunofluorescence studies showed that chronic TES exposure increased the expression of K_V1.2 and K_V1.5 in airway smooth muscle (ASM). In conclusion, chronic exposure to TES in guinea pig ASM promotes upregulation of K_V1.2 and K_V1.5 and enhances theophylline relaxation response. Therefore, gender should be considered when prescribing methylxanthines, as teenage boys and males are likely to respond better than females.

Supplementation With Spirulina platensis Improves Tracheal Reactivity in Wistar Rats by Modulating Inflammation and Oxidative Stress

Spirulina platensis has shown effectiveness in the treatment of allergic rhinitis in rats, but its action in tracheal reactivity or on markers of relaxation and antioxidant profile has not yet been possible to determine. In this paper, the animals were divided into the groups healthy (SG) and supplemented with S. platensis at doses of 50 (SG50), 150 (SG150), and 500 mg/kg (SG500). We also evaluated nitrite levels, lipid peroxidation, and antioxidant activity through biochemical analysis. For contractile reactivity, only SG500 (pEC50 = 5.2 ± 0.06 showed reduction in carbachol contractile potency. Indomethacin caused a higher contractile response to carbachol in SG150 and SG500. For relaxation, curves for SG150 (pEC50 = 5.0 ± 0.05) and SG500 (pEC50 = 7:3 ± 0:02) were shifted to the left, more so in SG500. We observed an increase in nitrite in the trachea only with supplementation of 500 mg/kg (54.0 ± 8.0 µM), also when compared to SG50 (37.0 ± 10.0 µM) and SG150 (38.0 ± 7.0 µM). We observed a decrease in lipid peroxidation in the plasma and an increase in oxidation inhibition for the trachea and lung in SG150 and SG500, suggesting enhanced antioxidant activity. S. platensis (150/500 mg/kg) decreased the contractile response and increased relaxation by increasing antioxidant activity and nitrite levels and modulating the inflammatory response.

Could Lower Testosterone in Older Men Explain Higher COVID-19 Morbidity and Mortalities?

The health scourge imposed on humanity by the COVID-19 pandemic seems not to recede. This fact warrants refined and novel ideas analyzing different aspects of the illness. One such aspect is related to the observation that most COVID-19 casualties were older males, a tendency also noticed in the epidemics of SARS-CoV in 2003 and the Middle East respiratory syndrome in 2012. This gender-related difference in the COVID-19 death toll might be directly involved with testosterone (TEST) and its plasmatic concentration in men. TEST has been demonstrated to provide men with anti-inflammatory and immunological advantages. As the plasmatic concentration of this androgen decreases with age, the health benefit it confers also diminishes. Low plasmatic levels of TEST can be determinant in the infection’s outcome and might be related to a dysfunctional cell Ca²⁺ homeostasis. Not only does TEST modulate the activity of diverse proteins that regulate cellular calcium concentrations, but these proteins have also been proven to be necessary for the replication of many viruses. Therefore, we discuss herein how TEST regulates different Ca²⁺-handling proteins in healthy tissues and propose how low TEST concentrations might facilitate the replication of the SARS-CoV-2 virus through the lack of modulation of the mechanisms that regulate intracellular Ca²⁺ concentrations.

Transient receptor potential cation channel subfamily V (TRPV) and its importance in asthma

Transient receptor potential (TRP) ion channels play critical roles in physiological and pathological conditions. Increasing evidence has unveiled the contribution of TRP vanilloid (TRPV) family in the development of asthma. The TRPV family is a group (TRPV1-TRPV6) of polymodal channels capable of sensing thermal, acidic, mechanical stress, and osmotic stimuli. TRPVs can be activated by endogenous ligands including, arachidonic acid derivatives or endocannabinoids. While TRPV1-TRPV4 are non-selective cation channels showing a predominance for Ca²⁺ over Na ⁺ influx, TRPV5 and TRPV6 are only Ca²⁺ permeable selective channels. Asthma is a chronic inflammatory bronchopulmonary disorder involving airway hyperresponsiveness (AHR) and airway remodeling. Patients suffering from allergic asthma display an inflammatory pattern driven by cytokines produced in type-2 helper T cells (Th2) and type 2 innate lymphoid cells (ILC2s). Ion channels are essential regulators in airway smooth muscle (ASM) and immune cells physiology. In this review, we summarize the contribution of TRPV1, TRPV2, and TRPV4 to the pathogenesis of asthma. TRPV1 is associated with hypersensitivity to environmental pollutants and chronic cough, inflammation, AHR, and remodeling. TRPV2 is increased in peripheral lymphocytes of asthmatic patients. TRPV4 contributes to ASM cells proliferation, and its blockade leads to a reduced eosinophilia, neutrophilia, as well as an abolished AHR. In conclusion, TRPV2 may represent a novel biomarker for asthma in children; meanwhile, TRPV1 and TRPV4 seem to be essential contributors to the development and exacerbations of asthma. Moreover, these channels may serve as novel therapeutic targets for this ailment.

Sex Hormones and Lung Inflammation

Inflammation is a characteristic marker in numerous lung disorders. Several immune cells, such as macrophages, dendritic cells, eosinophils, as well as T and B lymphocytes, synthetize and release cytokines involved in the inflammatory process. Gender differences in the incidence and severity of inflammatory lung ailments including asthma, chronic obstructive pulmonary disease (COPD), pulmonary fibrosis (PF), lung cancer (LC), and infectious related illnesses have been reported. Moreover, the effects of sex hormones on both androgens and estrogens, such as testosterone (TES) and 17β-estradiol (E2), driving characteristic inflammatory patterns in those lung inflammatory diseases have been investigated. In general, androgens seem to display anti-inflammatory actions, whereas estrogens produce pro-inflammatory effects. For instance, androgens regulate negatively inflammation in asthma by targeting type 2 innate lymphoid cells (ILC2s) and T-helper (Th)-2 cells to attenuate interleukin (IL)-17A-mediated responses and leukotriene (LT) biosynthesis pathway. Estrogens may promote neutrophilic inflammation in subjects with asthma and COPD. Moreover, the activation of estrogen receptors might induce tumorigenesis. In this chapter, we summarize the most recent advances in the functional roles and associated signaling pathways of inflammatory cellular responses in asthma, COPD, PF, LC, and newly occurring COVID-19 disease. We also meticulously deliberate the influence of sex steroids on the development and progress of these common and severe lung diseases.

Testosterone-to-estradiol ratio and lung function in a prospective study of Puerto Rican youth

BACKGROUND

Age- and sex-related differences in asthma may be due to changes in sex hormone levels.

OBJECTIVE

To evaluate whether a change in free testosterone or free testosterone-to-estradiol ratio is associated with changes in lung function and eosinophils in the Puerto Rican youth.

METHODS

We tested for the association between the change in sex hormone levels and change in lung function or change in eosinophils in a prospective study of 317 children (with and without asthma) followed up from ages 6 to 14 years to ages 10 to 20 years (146 females, 171 males) in San Juan, Puerto Rico. Serum levels of testosterone, estradiol, sex hormone-binding globulin, and progesterone were measured at 2 study visits, approximately 4.9 years apart. Using testosterone and sex hormone-binding globulin levels, we derived free testosterone and the free testosterone-to-estradiol ratio. Multivariable linear regression was used for the analysis of change in lung function and eosinophils, conducted separately by sex.

RESULTS

In girls, each quartile increment in the free testosterone-to-estradiol ratio was associated with a 2.03% increment in percent predicted forced expiratory volume in 1 second (FEV₁)/forced vital capacity (FVC) between study visits. In males, each quartile increment in the free testosterone-to-estradiol ratio was associated with a 3.27% increment in percent predicted FEV₁ and a 1.81% increment in percent predicted FEV₁/FVC between study visits. In girls with asthma, an increased free testosterone-to-estradiol ratio was significantly associated with decreased eosinophils between visits (P=0.03).

CONCLUSION

In Puerto Rican youth, increased free testosterone-to-estradiol ratio over time was associated with an increased FEV₁/FVC in both sexes, and with an increased FEV₁ in males.

Sex-Steroid Signaling in Lung Diseases and Inflammation

Sex/gender difference exists in the physiology of multiple organs. Recent epidemiological reports suggest the influence of sex-steroids in modulating a wide variety of disease conditions. Sex-based discrepancies have been reported in pulmonary physiology and various chronic inflammatory responses associated with lung diseases like asthma, chronic obstructive pulmonary disease (COPD), pulmonary fibrosis, and rare lung diseases. Notably, emerging clinical evidence suggests that several respiratory diseases affect women to a greater degree, with increased severity and prevalence than men. Although sex-specific differences in various lung diseases are evident, such differences are inherent to sex-steroids, which are major biological variables in men and women who play a central role to control these differences. The focus of this chapter is to comprehend the sex-steroid biology in inflammatory lung diseases and to understand the mechanistic role of sex-steroids signaling in regulating these diseases. Exploring the roles of sex-steroid signaling in the regulation of lung diseases and inflammation is crucial for the development of novel and effective therapy. Overall, we will illustrate the importance of differential sex-steroid signaling in lung diseases and their possible clinical implications for the development of complementary and alternative medicine to treat lung diseases.

Wnt Signaling Is Deranged in Asthmatic Bronchial Epithelium and Fibroblasts

Both canonical and non-canonical Wnt signaling pathway alterations have been documented in pulmonary disease pathogenesis and progression; therefore, they can be an attractive target for pharmaceutical management of severe asthma. Wnt/β-catenin signaling was shown to link early embryonic lung development impairment to later in life asthmatic airway remodeling. Here we explored the changes in Wnt signaling associated with asthma initiation and progression in epithelial and fibroblasts using a comprehensive approach based on in silico analysis and followed by in vitro validation. In summary, the in silico analysis showed that the bronchial epithelium of severe asthmatic patients showed a deranged balance between Wnt enhancer and Wnt inhibitors. A Th2-high phenotype is associated with upregulated Wnt-negative regulators, while inflammatory and neutrophilic severe asthmatics showed higher canonical Wnt signaling member enrichment. Most of these genes are regulators of healthy lung development early in life and, if disturbed, can make people susceptible to developing asthma early in life and prone to developing a severe phenotype. Most of the Wnt members are secreted, and their effect can be in an autocrine fashion on the bronchial epithelium, paracrine on nearby adjacent structural cells like fibroblasts and smooth muscles, or systemic in blood. Our results showed that canonical Wnt signaling is needed for the proper response of cells to proliferative stimuli, which puts cells under stress. Cells in response to this proliferative stress will activate the senescence mechanism, which is also dependent on Wnt signaling. Inhibition of Wnt signaling using FH535 inhibits both proliferation and senescence markers in bronchial fibroblasts compared to DMSO-treated cells. In fibroblasts from asthmatic patients, inhibition of Wnt signaling did not show that effect as the Wnt signaling is deranged besides other pathways that might be non-functional.

Androgen receptor activation alleviates airway hyperresponsiveness, inflammation, and remodeling in a murine model of asthma

Epidemiological studies demonstrate an apparent sex-based difference in the prevalence of asthma, with a higher risk in boys than girls, which is reversed postpuberty, where women become more prone to asthma than men, suggesting a plausible beneficial role for male hormones, especially androgens as a regulator of pathophysiology in asthmatic lungs. Using a murine model of asthma developed with mixed allergen (MA) challenge, we report a significant change in airway hyperresponsiveness (AHR), as demonstrated by increased thickness of epithelial and airway smooth muscle layers and collagen deposition, as well as Th2/Th17-biased inflammation in the airways of non-gonadectomized (non-GDX) and gonadectomized (GDX) male mice. Here, compared with non-GDX mice, MA-induced AHR and inflammatory changes were more prominent in GDX mice. Activation of androgen receptor (AR) using 5α-dihydrotestosterone (5α-DHT, AR agonist) resulted in decreased Th2/Th17 inflammation and remodeling-associated changes, resulting in improved lung function compared with MA alone challenged mice, especially in GDX mice. These changes were not observed with Flutamide (Flut, AR antagonist). Overall, we show that AR exerts a significant and beneficial role in asthma by regulating AHR and inflammation.

Non-genomic actions of sex hormones on pregnant uterine contractility in rats: An in vitro study at term

AIMS

The non-genomic (prompt) actions of sex steroids on pregnant uterine contractility are not fully explored yet, the aim of our study was to clarify such effects of 17-β estradiol (E2), progesterone (P4) and testosterone (T) on late (22-day) pregnant uterine contractions together with the signaling pathways in rats in vitro.

METHODS

The uterine effects of sex steroids on KCl-stimulated contractions were examined in the presence of genomic pathway blocker actinomycin D and cycloheximide, sex hormone receptor antagonists (flutamide, fulvestrant, mifepristone) and also after removing the endometrium. The modifications in uterine G-protein activation and cAMP levels were also detected.

RESULTS

T and E2 both relaxed the uterine contractions in the concentration range of 10^-8-10^-3 M with an increase in the activated G-protein and cAMP levels of the uterus, while P4 was ineffective. Cycloheximide, actinomycin D, antagonist for T and E2 were not able to modify the responses along with the endothelium removal. Mifepristone blocked the relaxing effects of T and E2 and reduced the activation of G-protein and the formation of cAMP.

SIGNIFICANCE

T and E2 can inhibit KCl-stimulated contractions in the late pregnant uterus in high concentrations and in a non-genomic manner. Their actions are mediated by a G-protein coupled receptor that can be blocked by mifepristone. A single and high dose of T or E2 might be considered in premature contractions, however, further preclinical and clinical studies are required for the approval of such a therapeutic intervention.

Sex steroids skew ACE2 expression in human airway: a contributing factor to sex differences in COVID-19?

The incidence, severity, and mortality of ongoing coronavirus infectious disease 19 (COVID-19) is greater in men compared with women, but the underlying factors contributing to this sex difference are still being explored. In the current study, using primary isolated human airway smooth muscle (ASM) cells from normal males versus females as a model, we explored the effect of estrogen versus testosterone in modulating the expression of angiotensin converting enzyme 2 (ACE2), a cell entry point for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Using confocal imaging, we found that ACE2 is expressed in human ASM. Furthermore, Western analysis of ASM cell lysates showed significantly lower ACE2 expression in females compared with males at baseline. In addition, ASM cells exposed to estrogen and testosterone for 24 h showed that testosterone significantly upregulates ACE2 expression in both males and females, whereas estrogen downregulates ACE2, albeit not significant compared with vehicle. These intrinsic and sex steroids induced differences may help explain sex differences in COVID-19.

Serum free testosterone and asthma, asthma hospitalisations and lung function in British adults

OBJECTIVE

We examined the relation between serum-free testosterone and asthma, wheeze, asthma hospitalisations and lung function in older adults.

DESIGN

Cross-sectional study.

SETTING

UK.

PARTICIPANTS

256 419 adults aged 40 to 69 years, recruited from 2006 to 2010.

MAIN OUTCOME MEASURES

Multivariable logistic or linear regression was used for the analysis of free testosterone and physician-diagnosed asthma, current wheeze, asthma hospitalisations and lung function measures, which was adjusted for serum estradiol, smoking status and other covariates.

RESULTS

Free testosterone levels above the lowest quartile (Q1) were significantly associated with lower odds of asthma in both women (adjusted OR (aOR) for Q4 (the highest quartile) versus Q1=0.67, 95% CI=0.64 to 0.71) and men (aOR for Q4 versus Q1=0.87, 95% CI=0.82 to 0.91). Among subjects with asthma, free testosterone levels above Q1 were significantly associated with lower odds of current wheeze in women (aOR range=0.78 to 0.87), and free testosterone levels in Q4 were associated with lower odds of current wheeze in men (aOR for Q4 versus Q1=0.86, 95% CI=0.77 to 0.95). Among women with asthma, free testosterone levels in Q4 were also associated with lower odds of ≥1 asthma hospitalisation. Among men, free testosterone was positively associated with FEV₁ and FVC. Among women, free testosterone was negatively and weakly associated with FVC.

CONCLUSION

In a large study of British adults, elevated free testosterone levels are associated with lower odds of asthma and current wheeze in women and men, lower odds of asthma hospitalisations in women, and higher FEV₁ and FVC in men. DISSEMINATION TO PARTICIPANTS, AND RELATED PATIENT AND PUBLIC COMMUNITIES: The results of the study will be linked to the UK Biobank website.

Aster tataricus attenuates asthma efficiently by simultaneously inhibiting tracheal ring contraction and inflammation

Asthma is an airway chronic inflammatory disease with significant morbidity, mortality and huge social economic burden. Previous research demonstrated that the root of Aster tataricus (RA) may have the potential to treat asthma, but the efficacy and mechanism were not clear. In this study, preliminary results in vitro showed that Fr-75 eluted from RA extract could not only completely inhibit the tracheal ring contraction raised by KCl in 20 min, but also effectively affect the tracheal ring contraction induced by KCl-, Ach- and His in a concentration-dependent manner (3.91-250 μg/mL). Further results on cells exhibited that Fr-75 could decrease the concentration of intracellular Ca²⁺ as well. These results revealed the underlying mechanism in vitro that the inhibition of tracheal ring contraction might be due to the decline of the intracellular Ca²⁺ concentration, which caused by suppressing calcium channel, antagonizing the muscarinic and histamine receptors. Also, results in vivo exhibited that Fr-75 could distinctly ease the symptoms of ovalbumin-sensitized mice, including relieving the pathological injury, increasing the latency to preconvulsive dyspnea and to enhanced pause, reducing the inflammatory cells, chemokines and cytokines in BALF and lung tissue. In general, it could be speculated that RA fraction may attenuate asthma through dilating the tracheal ring contraction and alleviating the lung inflammation simultaneously.

Testosterone augments β2 adrenergic receptor genomic transcription increasing salbutamol relaxation in airway smooth muscle

Androgens in asthmatic men may be linked to asthma severity, acting via nongenomic and genomic effects. This ailment affects boys more than girls during infancy, and this proportion reverses in puberty. Plasmatic androgen concentration in young men increases at this age and might be related to lower asthma symptoms. Nongenomic actions occur in a brief period and are independent of the androgen receptor (AR), while genomic effects depend on AR, take hours-days and are modified by transcription or protein synthesis inhibitors. Guinea pig tracheas chronic incubation with testosterone (TES, 40 nM, 48 h) potentiates salbutamol-induced relaxation, an effect that was reversed by flutamide, not observed when tissues were pre-incubated with TES-bovine serum albumin (TES-BSA) nor when tissues were preincubated with TES for 15-60 min. In tracheal myocytes, TES chronic incubation increases salbutamol-induced K⁺ currents (IK⁺), an effect that was also reversed by flutamide, actinomycin D and cycloheximide and not seen with TES-BSA. The increment in IK⁺ was blocked by 4-aminopyridine and iberiotoxin, indicating that delayed rectifier K⁺ and high-conductance Ca²⁺ activated K⁺ channels were involved in the TES potentiation effect. Immunofluorescence studies showed that chronic TES augmented the β₂ adrenergic receptor (β₂-AR) expression in ASM and this finding was corroborated by q-PCR and Western blot assays. β₂-AR affinity for salbutamol after TES incubation was increased. In conclusion, chronic exposure to physiological TES concentration of the guinea pig ASM promotes β₂-AR upregulation favoring β₂ adrenergic responses and probably limiting the severity of the asthmatic exacerbations in teenage boys and men.

Vascular mechanisms of testosterone: The non-genomic point of view

Testosterone (T) is the predominant endogenous androgen in the bloodstream. At the vascular level, T presents genomic and non-genomic effects, and both effects may overlap. The genomic actions assume that androgens can freely cross the plasma membrane of target cells and bind to nuclear androgen receptors, inducing gene transcription and protein synthesis. The non-genomic effects have a more rapid onset and may be related to the interaction with protein/receptor/ion channels of the plasma membrane. The key T effect at the vascular level is vasorelaxation, which is primarily due to its rapid effect. Thus, the main purpose of this review is to discuss the T non-genomic effects at the vascular level and the molecular pathways involved in its vasodilator effect observed in in vivo and in vitro studies. In this sense, the nuclear receptor activation, the influence of vascular endothelium and the activation or inhibition of ion channels (potassium and calcium channels, respectively) will be reviewed regarding all the data that corroborated or not. Moreover, this review also provides a brief update on the association of T with the risk factors for cardiovascular diseases, namely metabolic syndrome, type 2 diabetes mellitus, obesity, atherosclerosis, dyslipidaemia, and hypertension. In summary, in this paper we consider the non-genomic vascular mode of action of androgen in physiological conditions and the main risk factors for cardiovascular diseases.

Androgen Effects on the Adrenergic System of the Vascular, Airway, and Cardiac Myocytes and Their Relevance in Pathological Processes

INTRODUCTION

Androgen signaling comprises nongenomic and genomic pathways. Nongenomic actions are not related to the binding of the androgen receptor (AR) and occur rapidly. The genomic effects implicate the binding to a cytosolic AR, leading to protein synthesis. Both events are independent of each other. Genomic effects have been associated with different pathologies such as vascular ischemia, hypertension, asthma, and cardiovascular diseases. Catecholamines play a crucial role in regulating vascular smooth muscle (VSM), airway smooth muscle (ASM), and cardiac muscle (CM) function and tone.

OBJECTIVE

The aim of this review is an updated analysis of the role of androgens in the adrenergic system of vascular, airway, and cardiac myocytes. Body. Testosterone (T) favors vasoconstriction, and its concentration fluctuation during life stages can affect the vascular tone and might contribute to the development of hypertension. In the VSM, T increases α1-adrenergic receptors (α ₁-ARs) and decreases adenylyl cyclase expression, favoring high blood pressure and hypertension. Androgens have also been associated with asthma. During puberty, girls are more susceptible to present asthma symptoms than boys because of the increment in the plasmatic concentrations of T in young men. In the ASM, β ₂-ARs are responsible for the bronchodilator effect, and T augments the expression of β ₂-ARs evoking an increase in the relaxing response to salbutamol. The levels of T are also associated with an increment in atherosclerosis and cardiovascular risk. In the CM, activation of α _1A-ARs and β ₂-ARs increases the ionotropic activity, leading to the development of contraction, and T upregulates the expression of both receptors and improves the myocardial performance.

CONCLUSIONS

Androgens play an essential role in the adrenergic system of vascular, airway, and cardiac myocytes, favoring either a state of health or disease. While the use of androgens as a therapeutic tool for treating asthma symptoms or heart disease is proposed, the vascular system is warmly affected.

Androgens are effective bronchodilators with anti-inflammatory properties: A potential alternative for asthma therapy

Changes in plasma androgen levels in asthmatic men may be linked to asthma severity, seemingly acting through nongenomic and genomic effects. Nongenomic effects include rapid relaxation of carbachol or antigenic challenge pre-contracted guinea pig airway smooth muscle (ASM) in vitro: testosterone (TES) blocks l-type voltage dependent Ca²⁺ channels, stored operated Ca²⁺ channels, inositol 1,4,5-trisphosphate receptors and promotes prostaglandin E₂ biosynthesis. In ASM at rest, TES lowers basal intracellular Ca²⁺ concentration and tension, maintaining a proper airway patency keeping steady smooth muscle tension and basal intracellular Ca²⁺ concentration at rest. Moreover, the bronchospasm in sensitized guinea-pigs was ablated by dehydroepiandrosterone (DHEA), a precursor of steroids, TES and its metabolites 5α- and 5β-dihydrotestosterone (DHT). On the other hand, genomic effects related to androgens' anti-inflammatory properties in asthma have been recently studied. Briefly, TES negatively regulates type 2 immune response sustained by CD4+ Th2 and group 2 innate lymphoid cells, diminishing allergic airway inflammation in males. Also, novel findings establish that TES decreases interleukin (IL)-17A protein expression produced by CD4+ Th17 cells and therefore neutrophilic airway inflammation. Clearly, DHEA, TES or its 5β-reduced metabolite that possesses minimal androgenic effect, might have potential therapeutic capacities in the treatment of severe asthma via mechanisms distinct from corticosteroid treatment.

Factors related to changes in the asthma male: female ratio by age in 403 Mexican counties

BACKGROUND

Asthma is more frequent in males during childhood and in females after adolescence, which has been attributed to changes in sexual hormones levels.

OBJECTIVE

We explored changes of the asthma male: female ratio (AMFR) by age group in a large population (nationwide), and its ecological association (at county level) with some medical, geographical, or sociodemographic factors.

METHODS

Registries of the largest medical institution in Mexico (∼37.5 million subjects assigned to a family physician) were analyzed and the AMFR calculated using asthma incidences.

RESULTS

In boys, asthma incidence peaked at 0 to 4 years and progressively decreased, reaching a plateau in adulthood. In girls, asthma incidence showed a bimodal pattern, with maximal rates at 0 to 4 years old, and again at 50 to 54 years old. In the ecological analysis performed in more than 400 counties, the AMFR in adults (≥15 years old) inversely correlated with population density (r = -0.256) and altitude (r = -0.144), and directly correlated with acute respiratory tract infections (ARTI, r = 0.215), diabetes (r = 0.186), marginalization (r = 0.179), pneumonias (r = 0.166), and mean maximal temperature (r = 0.142), all with P < .01. In the multiple linear regression, only population density (P < .001) and ARTI (P = .006) remained statistically significant in the final model.

CONCLUSION

Asthma incidence in males and females did not match the expected sexual hormones variations, and other factors such as population density and ARTI also influenced the AMFR. These findings challenge the traditional belief that sexual hormones are major determinants of the AMFR.

Androgen Receptor-Mediated Regulation of Intracellular Calcium in Human Airway Smooth Muscle Cells

BACKGROUND/AIMS

With the prevalence of asthma being greater in women, detrimental effects of female sex steroids have been explored, but potential protective effects of androgens are not established. Airway smooth muscle (ASM) is a key cell type in contractility and remodelling of asthma. There are no data on expression and functionality of androgen receptor (AR) in human ASM cells.

METHODS

We used primary human ASM cells from non-asthmatics vs. asthmatics to determine AR expression at baseline and with inflammation measured using Western blotting/qRT-PCR, and the role of AR in regulating intracellular Ca2+ ([Ca2+]i) measured using Fluo-3 loaded real time [Ca2+]i imaging.

RESULTS

We found that compared to females, baseline AR is greater in male ASM and increases with inflammation/asthma. Androgens, via AR, blunted TNFα or IL-13-induced enhancement of ASM [Ca2+]i in both males and females, with retained efficacy in asthmatics. AR effects involve reduced Ca2+ influx via L-type channels and store-operated Ca2+ entry, the latter by downregulating STIM1 and Orai1 and increasing TMEM66.

CONCLUSION

Our data show AR expression is increased in female ASM with asthma, but has retained functionality that could be used to reduce [Ca2+]i towards alleviating airway hyperresponsiveness.

Maintenance of intracellular Ca2+ basal concentration in airway smooth muscle (Review)

In airway smooth muscle, the intracellular basal Ca²⁺ concentration [_b(Ca²⁺)_i] must be tightly regulated by several mechanisms in order to maintain a proper airway patency. The _b[Ca²⁺]_i is efficiently regulated by sarcoplasmic reticulum Ca²⁺-ATPase 2b, plasma membrane Ca²⁺-ATPase 1 or 4 and by the Na⁺/Ca²⁺ exchanger. Membranal Ca²⁺ channels, including the L-type voltage dependent Ca²⁺ channel (L-VDCC), T-type voltage dependent Ca²⁺ channel (T-VDCC) and transient receptor potential canonical 3 (TRPC3), appear to be constitutively active under basal conditions via the action of different signaling pathways, and are responsible for Ca²⁺ influx to maintain _b[Ca²⁺]_i. The two types of voltage-dependent Ca²⁺ channels (L- and T-type) are modulated by phosphorylation processes mediated by mitogen-activated protein kinase kinase (MEK) and extracellular-signal-regulated kinase 1 and 2 (ERK1/2). The MEK/ERK signaling pathway can be activated by G-protein-coupled receptors through the α_q subunit when the endogenous ligand (i.e., acetylcholine, histamine, leukotrienes, etc.) is present under basal conditions. It may also be stimulated when receptor tyrosine kinases are occupied by the appropriate ligand (cytokines, growth factors, etc.). ERK1/2 phosphorylates L-VDCC on Ser⁴⁹⁶ of the β₂ subunit and Ser¹⁹²⁸ of the α₁ subunit, decreasing or increasing the channel activity, respectively, and enabling it to switch between an open and closed state. T-VDCC is also probably phosphorylated by ERK1/2, although further research is required to identify the phosphorylation sites. TRPC3 is directly activated by diacylglycerol produced by phospholipase C (PLC_β or _γ). Constitutive inositol 1,4,5-trisphosphate production induces the release of Ca²⁺ from the sarcoplasmic reticulum through inositol triphosphate receptor 1. This ion induces Ca²⁺-induced Ca²⁺ release through the ryanodine receptor 2 (designated as Ca²⁺ ‘sparks’). Therefore, several Ca²⁺ handling mechanisms are finely tuned to regulate basal intracellular Ca²⁺ concentrations. It is conceivable that alterations in any of these processes may render airway smooth muscle susceptible to develop hyperresponsiveness that is observed in ailments such as asthma.

Testosterone Decreases House Dust Mite-Induced Type 2 and IL-17A-Mediated Airway Inflammation

As adults, women are twice as likely as men to have asthma; however, the mechanisms explaining this sexual dimorphism remain unclear. Increased type 2 cytokines and/or IL-17A, leading to increased airway eosinophils and neutrophils, respectively, are associated with asthma. Previous studies showed that testosterone, signaling through the androgen receptor (AR), decreased Th2-mediated allergic inflammation and type 2 innate immune responses during allergic inflammation. Therefore, we hypothesized that testosterone and AR signaling attenuate type 2 and IL-17A-mediated airway inflammation. To test our hypothesis, sham-operated and gonadectomized female and male mice were intranasally challenged with house dust mite (HDM) or vehicle (PBS) for 3 wk. Testosterone decreased and ovarian hormones increased HDM-induced eosinophilic and neutrophilic inflammation, IgE production, and airway hyperresponsiveness, as well as decreased the numbers of IL-13⁺ CD4 Th2 cells and IL-17A⁺ CD4 Th17 cells in the lung. Next, using wild-type male and female mice and AR^tfm male mice that are unable to signal through the AR, we determined AR signaling intrinsically attenuated IL-17A⁺ Th17 cells but indirectly decreased IL-13⁺ CD4 Th2 cells in the lung by suppressing HDM-induced IL-4 production. In vitro Th2 and Th17 differentiation experiments showed AR signaling had no direct effect on Th2 cell differentiation but decreased IL-17A protein expression and IL-23R mRNA relative expression from Th17 cells. Combined, these findings show AR signaling attenuated type 2 and IL-17A inflammation through different mechanisms and provide a potential explanation for the increased prevalence of asthma in women compared with men.