Endocrine regulation of airway contractility is overlooked

Allosteric modulator potentiates β2AR agonist-promoted bronchoprotection in asthma models

Asthma is a chronic inflammatory disease associated with episodic airway narrowing. Inhaled β2-adrenergic receptor (β2AR) agonists (β2-agonists) promote - with limited efficacy - bronchodilation in asthma. All β2-agonists are canonical orthosteric ligands that bind the same site as endogenous epinephrine. We recently isolated a β2AR-selective positive allosteric modulator (PAM), compound-6 (Cmpd-6), which binds outside of the orthosteric site and modulates orthosteric ligand functions. With the emerging therapeutic potential of G-protein coupled receptor allosteric ligands, we investigated the impact of Cmpd-6 on β2AR-mediated bronchoprotection. Consistent with our findings using human β2ARs, Cmpd-6 allosterically potentiated β2-agonist binding to guinea pig β2ARs and downstream signaling of β2ARs. In contrast, Cmpd-6 had no such effect on murine β2ARs, which lack a crucial amino acid in the Cmpd-6 allosteric binding site. Importantly, Cmpd-6 enhanced β2 agonist-mediated bronchoprotection against methacholine-induced bronchoconstriction in guinea pig lung slices, but - in line with the binding studies - not in mice. Moreover, Cmpd-6 robustly potentiated β2 agonist-mediated bronchoprotection against allergen-induced airway constriction in lung slices obtained from a guinea pig model of allergic asthma. Cmpd-6 similarly enhanced β2 agonist-mediated bronchoprotection against methacholine-induced bronchoconstriction in human lung slices. Our results highlight the potential of β2AR-selective PAMs in the treatment of airway narrowing in asthma and other obstructive respiratory diseases.

Mechanistic Links Between Obesity and Airway Pathobiology Inform Therapies for Obesity-Related Asthma

Obesity-related asthma is associated with a high disease burden and a poor response to existent asthma therapies, suggesting that it is a distinct asthma phenotype. The proposed mechanisms that contribute to obesity-related asthma include the effects of the mechanical load of obesity, adipokine perturbations, and immune dysregulation. Each of these influences airway smooth muscle function. Mechanical fat load alters airway smooth muscle stretch affecting airway wall geometry, airway smooth muscle contractility, and agonist delivery; weight loss strategies, including medically induced weight loss, counter these effects. Among the metabolic disturbances, insulin resistance and free fatty acid receptor activation influence distinct signaling pathways in the airway smooth muscle downstream of both the M2 muscarinic receptor and the β2 adrenergic receptor, such as phospholipase C and the extracellular signal-regulated kinase signaling cascade. Medications that decrease insulin resistance and dyslipidemia are associated with a lower asthma disease burden. Leptin resistance is best understood to modulate muscarinic receptors via the neural pathways but there are no specific therapies for leptin resistance. From the immune perspective, monocytes and T helper cells are involved in systemic pro-inflammatory profiles driven by obesity, notably associated with elevated levels of interleukin-6. Clinical trials on tocilizumab, an anti-interleukin antibody, are ongoing for obesity-related asthma. This armamentarium of therapies is distinct from standard asthma medications, and once investigated for its efficacy and safety among children, will serve as a novel therapeutic intervention for pediatric obesity-related asthma. Irrespective of the directionality of the association between asthma and obesity, airway-specific mechanistic studies are needed to identify additional novel therapeutic targets for obesity-related asthma.

The impacts of parity on spirometric parameters: a systematic review

Introduction: The relationship between parity and health outcomes has been debated in the scientific literature in terms of 'selection-pressure'. However, no previous review has raised the impacts of parity on spirometric parameters. This Systematic Review aimed to review the impacts of parity on spirometric parameters.Areas covered: PubMed and Scopus were searched on October 1^st, 2020, using the combination of the following two medical subject headings: 'Parity' and 'Respiratory Function Tests'. Only original articles published in English/French were retained. Ten studies investigated the impacts of parity on spirometric parameters: six included healthy females, three involved unhealthy females [chronic obstructive pulmonary disease, defect in protease inhibitor, and some other conditions] and one included a mixed population of healthy/unhealthy females. The studies reported conflicting results: no impact, positive impact (multiparity is associated with larger forced-expiratory-volume in one second, forced- and slow- vital-capacity, and inspiratory-capacity), or negative impact (multiparous females has lower bronchial flows, higher static volumes, an accelerated lung-aging, a tendency to an obstructive-ventilatory-defect and/or to lung-hyperinflation, and increased protease inhibitor levels).Expert opinion: The ten studies presented some limitations that made data interpretation relatively difficult. Future research to identify the 'real' impact of parity on spirometric parameters are therefore encouraged.

Association between obesity and lung function changes by sex and age in adults with asthma

OBJECTIVE

The lung function changes presenting before and after asthma treatment in obese people remain largely unknown. This study aimed to investigate the association between obesity and lung function changes before and after treatment in adults with asthma.

METHODS

We enrolled 937 newly diagnosed asthma patients from Cohort for Reality and Evolution of Adult Asthma in Korea cohort in 2015-2017, who performed follow-up spirometry after three months of asthma treatment. The percentage changes (Δ) between the spirometry results before and after treatment were calculated. Patients were categorized into four body mass index (BMI) groups; underweight (<18.5), normal (18.5-22.9), overweight (23.0-24.9), and obese (≥25.0). Association between percent change of pulmonary function and BMI was analyzed according to sex and/or age (< 45 yrs, 45-65 yrs, ≥ 65 yrs), which were statistically corrected for age, sex, smoking status, and medication history.

RESULTS

There was no consistent correlation between BMI and each lung function parameter. However, there were significant differences between BMI and ΔFEV₁/FVC before and after 3 months of controller treatment. The obese asthmatics showed significantly lower ΔFEV₁/FVC (6.0 ± 13.5%) than the underweight (12.6 ± 21.4%, P = 0.044) or normal weight (9.1 ± 14.6%, P = 0.031). Middle-aged women had higher BMI (24.11 ± 3.60 vs. 22.39 ± 3.52) and lower ΔFEV₁/FVC (5.7 ± 11.9% vs. 8.9 ± 14.3%, P = 0.012) than young women.

CONCLUSIONS

Obesity is negatively correlated with the ΔFEV₁/FVC before and after controller treatment. Sex and age differentially contribute to lung function changes in response to asthma medications in adult asthmatics, showing a significant decrease in the ΔFEV₁/FVC in middle-aged women.

Effect of gestational and lactational nonylphenol exposure on airway inflammation in ovalbumin-induced asthmatic rat pups

To investigate the effect of gestational and lactational nonylphenol (NP) exposure on airway inflammation in ovalbumin (OVA)-induced asthmatic pups. Dams were gavaged with NP at dose levels of 25 mg/kg/day (low dose), 50 mg/kg/day (middle dose), 100 mg/kg/day (high dose) and groundnut oil alone (vehicle control) respectively from gestational day 7 to postnatal day 21. The results showed that the NP content in the lung tissues of pups in the 100 mg/kg NP group was significantly higher than that of the control group (P = 0.004). In the 100 mg/kg NP group, the infiltration of lymphocytes and eosinophils with thicken smooth muscle layer and inflammatory cells in the lumen were observed in the lung tissues of pups. Osmiophilic lamellar bodies were found in the cytoplasm of type II epithelial cells; mitochondria were clearly swollen. Compared with the control group, the levels of interleukin-4 (IL-4) in BALF (P = 0.042) and ovalbumin-specific serum immunoglobulin E (OVA-sIgE) (P = 0.005) in the OVA group were significantly higher. 25 mg/kg NP-OVA co-exposure synergistically decreased nuclear factor-κB (NF-κB) mRNA expression in the lung tissues of pups; Exposure to 50 mg/kg NP combined with OVA antagonized the increased expression of high mobility group box 1 (HMGB1) mRNA in the lung tissue. The combined exposure to 50 mg/kg NP and OVA synergistically increased HMGB1 protein expression in the lung tissues. 25 mg/kg NP-OVA co-exposure antagonized the increased nuclear factor-κB (NF-κB) protein expression in the lung tissues. There was a positive correlation between NP content and HMGB1 protein expression in the lung tissue of asthmatic pups (r = 0.602, P < 0.001). In conclusion, gestational and lactational exposure to 100 mg/kg NP in maternal rats exacerbated airway inflammation in OVA-induced asthmatic pups, and there is an interactive effect between NP and OVA. When the perinatal rats were exposed to 100 mg/kg NP, the levels of HMGB1 and NF-κB in the lung tissues of OVA-induced asthmatic pups were increased.

[Extracellular molecules controlling the contraction of airway smooth muscle and their potential contribution to bronchial hyperresponsiveness]

INTRODUCTION

A significant portion of symptoms in some lung diseases results from an excessive constriction of airways due to the contraction of smooth muscle and bronchial hyperresponsiveness. A better understanding of the extracellular molecules that control smooth muscle contractility is necessary to identify the underlying causes of the problem.

STATE OF KNOWLEDGE

Almost a hundred molecules, some of which newly identified, influence the contractility of airway smooth muscle. While some molecules activate the contraction, others activate the relaxation, thus acting directly as bronchoconstrictors and bronchodilators, respectively. Other molecules do not affect contraction directly but rather influence it indirectly by modifying the effect of bronchoconstrictors and bronchodilators. These are called bronchomodulators. Some of these bronchomodulators increase the contractile effect of bronchoconstrictors and could thus contribute to bronchial hyperresponsiveness.

PROSPECTS

Considering the high number of molecules potentially involved, as well as the level of functional overlap between some of them, identifying the extracellular molecules responsible for excessive airway constriction in a patient is a major contemporary challenge.

Virgin Coconut Oil Supplementation Prevents Airway Hyperreactivity of Guinea Pigs with Chronic Allergic Lung Inflammation by Antioxidant Mechanism

Asthma is a chronic inflammatory disease of the airways characterized by immune cell infiltrates, bronchial hyperresponsiveness, and declining lung function. Thus, the possible effects of virgin coconut oil on a chronic allergic lung inflammation model were evaluated. Morphology of lung and airway tissue exhibited peribronchial inflammatory infiltrate, epithelial hyperplasia, and smooth muscle thickening in guinea pigs submitted to ovalbumin sensitization, which were prevented by virgin coconut oil supplementation. Additionally, in animals with lung inflammation, trachea contracted in response to ovalbumin administration, showed a greater contractile response to carbachol (CCh) and histamine, and these responses were prevented by the virgin coconut oil supplementation. Apocynin, a NADPH oxidase inhibitor, did not reduce the potency of CCh, whereas tempol, a superoxide dismutase mimetic, reduced potency only in nonsensitized animals. Catalase reduced the CCh potency in nonsensitized animals and animals sensitized and treated with coconut oil, indicating the participation of superoxide anion and hydrogen peroxide in the hypercontractility, which was prevented by virgin coconut oil. In the presence of L-NAME, a nitric oxide synthase (NOS) inhibitor, the CCh curve remained unchanged in nonsensitized animals but had increased efficacy and potency in sensitized animals, indicating an inhibition of endothelial NOS but ineffective in inhibiting inducible NOS. In animals sensitized and treated with coconut oil, the CCh curve was not altered, indicating a reduction in the release of NO by inducible NOS. These data were confirmed by peribronchiolar expression analysis of iNOS. The antioxidant capacity was reduced in the lungs of animals with chronic allergic lung inflammation, which was reversed by the coconut oil, and confirmed by analysis of peribronchiolar 8-iso-PGF2α content. Therefore, the virgin coconut oil supplementation reverses peribronchial inflammatory infiltrate, epithelial hyperplasia, smooth muscle thickening, and hypercontractility through oxidative stress and its interactions with the NO pathway.

Female reproductive history in relation to chronic obstructive pulmonary disease and lung function in UK biobank: a prospective population-based cohort study

OBJECTIVES

Sex differences in respiratory physiology and predilection for developing chronic obstructive pulmonary disease (COPD) have been documented, suggesting that female sex hormones may influence pathogenesis. We investigated whether aspects of female reproductive health might play a role in risk of COPD among women.

DESIGN

Population-based prospective cohort study.

SETTING

UK Biobank recruited across 22 centres in the UK between 2006 to 2010.

PRIMARY AND SECONDARY OUTCOMES MEASURES

We examined a range of female reproductive health indicators in relation to risk of COPD-related hospitalisation/death (n=271 271) using Cox proportional hazards regression; and lung function (n=273 441) using linear regression.

RESULTS

Parity >3 was associated with greater risk of COPD-related hospitalisation/death (adjusted HR 1.45; 95% CI: 1.16 to 1.82) and lower forced expiratory volume at 1 second/forced vital capacity ratio (FEV₁/FVC) (adjusted mean difference -0.06; 95% CI: -0.07 to 0.04). Any oral contraception use was associated with lower risk of COPD-related hospitalisation/death (adjusted HR 0.85; 95% CI: 0.74 to 0.97) and greater FEV₁/FVC (adjusted mean difference 0.01; 95% CI: 0.003 to 0.03). Late menarche (age >15) and early menopause (age <47) were also associated with greater risk of COPD-related hospitalisation/death (but not lung function), while endometriosis was associated with greater FEV₁/FVC (not COPD-related hospitalisation/death). Early menarche (age <12 years) was associated with lower FEV₁/FVC (but not COPD hospitalisation/death). Associations with polycystic ovary syndrome (PCOS) or ovarian cysts, any hormone replacement therapy (HRT) use, hysterectomy-alone and both hysterectomy and bilateral oophorectomy were in opposing directions for COPD-related hospitalisation/death (greater risk) and FEV₁/FVC (positive association).

CONCLUSIONS

Multiple female reproductive health indicators across the life course are associated with COPD-related hospitalisation/death and lung function. Further studies are necessary to understand the opposing associations of PCOS/ovarian cysts, HRT and hysterectomy with COPD and objective measures of airway obstruction.

Dehydroepiandrosterone Supplementation May Benefit Women with Asthma Who Have Low Androgen Levels: A Pilot Study

Introduction

Among individuals with severe asthma, FEV₁ is low in individuals with low dehydroepiandrosterone (DHEA) sulfate (DHEAS) levels. In the Severe Asthma Research Program (SARP), no women with DHEAS > 200 μg/dL had an FEV₁ < 60% predicted. DHEA has benefited patients with COPD and pulmonary hypertension in small trials. Therefore, we hypothesized that DHEA supplementation may improve FEV₁ in asthmatic women with low DHEAS.

Methods

Premenopausal, nonsmoking, otherwise healthy women, 18-50 years old, with mild or moderate asthma and baseline FEV₁ > 60% predicted received 100 mg DHEA orally every 12 h for 2 weeks. Spirometry and DHEAS were measured at the initial visit and 2 weeks later, after completion of DHEA treatment. Based on our previous work, the primary outcome variable for this pilot study was post-albuterol spirometry in the low-DHEAS group. Subjects also continued their other routine asthma management.

Results

Serum DHEAS increased with DHEA treatment in women with starting DHEAS < 200 µg/dL: this increase was from 71 ± 23 to 725 ± 295 µg/dL (n = 10; p = 0.0001). The increase in the high-DHEAS group was smaller. Post-albuterol FEV₁ increased by 51 mL, from 3.026 ± 0.5 to 3.077 ± 0.49 L (n = 10; p = 0.034 by paired t test, significant after Bonferroni), in women with low DHEAS. In the high-DHEAS group (baseline DHEAS ≥ 200 µg/dl), post-albuterol FEV₁ did not change significantly (n = 3, p = NS). Three subjects were excluded: one had comorbid COPD, one could not perform spirometry, and one did not take the DHEA. There were no adverse effects of DHEA treatment in this trial.

Conclusions

Endocrine treatments (corticosteroids) are a mainstay of anti-inflammatory management for moderate and severe asthma. Their use has improved asthma outcomes. Androgens also reduce airway inflammation and promote airway smooth muscle relaxation, but are rarely used clinically for asthma treatment. Our results suggest that the over-the-counter steroid DHEA may improve lung function in asthma outcomes among women with DHEAS < 200 ug/dL.

Asthma, exercise and metabolic dysregulation in paediatrics

Asthma is the most frequent chronic disease in childhood. Chest tightness, cough, wheezing and dyspnoea during or after exercise may be unique manifestations of asthma in up to 90% of subjects. Physical activity may be reduced by uncontrolled asthma symptoms and parental beliefs, impairing physical fitness of asthmatic children. Clinicians working in the field of allergy are aware of evidence supporting the benefits of physical activity for patients with asthma. Treatment of asthma is required in order to obtain its control and to avoid any limitation in sports and active play participation. As exercise performance in children with controlled asthma is not different from that of healthy controls, any exercise limitation cannot be accepted. Overweight and obesity may interfere with asthma and exercise, leading to dyspnoea symptoms. Evidences on the effect of insulin resistance on airway smooth muscle and on bronchial hyperactivity are presented. CONCLUSION: Exercise is part of the strategy to obtain the best control of asthma in childhood, but we have to optimise the asthma control therapy before starting exercise programming. Furthermore, it is crucial to give best attention on the effects of obesity and insulin resistance, because they could in turn influence patients' symptoms.

Respiratory Effects and Systemic Stress Response Following Acute Acrolein Inhalation in Rats

Previous studies have demonstrated that exposure to the pulmonary irritant ozone causes myriad systemic metabolic and pulmonary effects attributed to sympathetic and hypothalamus-pituitary-adrenal (HPA) axis activation, which are exacerbated in metabolically impaired models. We examined respiratory and systemic effects following exposure to a sensory irritant acrolein to elucidate the systemic and pulmonary consequences in healthy and diabetic rat models. Male Wistar and Goto Kakizaki (GK) rats, a nonobese type II diabetic Wistar-derived model, were exposed by inhalation to 0, 2, or 4 ppm acrolein, 4 h/d for 1 or 2 days. Exposure at 4 ppm significantly increased pulmonary and nasal inflammation in both strains with vascular protein leakage occurring only in the nose. Acrolein exposure (4 ppm) also caused metabolic impairment by inducing hyperglycemia and glucose intolerance (GK > Wistar). Serum total cholesterol (GKs only), low-density lipoprotein (LDL) cholesterol (both strains), and free fatty acids (GK > Wistar) levels increased; however, no acrolein-induced changes were noted in branched-chain amino acid or insulin levels. These responses corresponded with a significant increase in corticosterone and modest but insignificant increases in adrenaline in both strains, suggesting activation of the HPA axis. Collectively, these data demonstrate that acrolein exposure has a profound effect on nasal and pulmonary inflammation, as well as glucose and lipid metabolism, with the systemic effects exacerbated in the metabolically impaired GKs. These results are similar to ozone-induced responses with the exception of lung protein leakage and ability to alter branched-chain amino acid and insulin levels, suggesting some differences in neuroendocrine regulation of these two air pollutants.

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.

Lung responses in murine models of experimental asthma: Value of house dust mite over ovalbumin sensitization

Ovalbumin (OVA) sensitization has limitations in modelling asthma. Thus, we examined the value of allergic sensitization using a purified natural allergen, house dust mite (HDM), over the sensitization performed with OVA. Mice were sham-treated, or sensitized with OVA- or HDM with identical chronology. Airway resistance, tissue damping and elastance were assessed under control conditions and after challenging the animals with methacholine (MCh) and the specific allergen. Inflammatory profile of the bronchoalveolar lavage fluid was characterized and lung histology was performed. While no difference in the lung responsiveness to the specific allergen was noted, hyperresponsiveness to MCh was observed only in the HDM-sensitized animals in the lung peripheral parameters. Lung inflammation differed between the models, but excessive bronchial smooth muscle remodelling occurred only with OVA. In conclusion, we demonstrate that a purified natural allergen offers a more relevant murine model of human allergic asthma by expressing the key features of this chronic inflammatory disease both in the lung function and structure.

Progestogen Hypersensitivity: An Evidence-Based Approach to Diagnosis and Management in Clinical Practice

Heterogeneous presentations of disease pose particular diagnostic and management challenges to the clinician. Progestogen hypersensitivity (PH) classically consists of hypersensitivity symptoms to endogenous progesterone during the luteal phase of the menstrual cycle. However, with the rise of assisted fertility and the exponential growth in the use of exogenous progestins for contraception, PH's prevalence and symptom heterogeneity have increased. In this article, we focus on the clinical approach to PH diagnosis with an emphasis on key elements of the history, physical, and testing modalities. We also review the current evidence for successful management and treatment across a broad range of patients.

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.

Pediatric Obesity-Related Asthma: The Role of Metabolic Dysregulation

The burden of obesity-related asthma among children, particularly among ethnic minorities, necessitates an improved understanding of the underlying disease mechanisms. Although obesity is an independent risk factor for asthma, not all obese children develop asthma. Several recent studies have elucidated mechanisms, including the role of diet, sedentary lifestyle, mechanical fat load, and adiposity-mediated inflammation that may underlie the obese asthma pathophysiology. Here, we review these recent studies and emerging scientific evidence that suggest metabolic dysregulation may play a role in pediatric obesity-related asthma. We also review the genetic and epigenetic factors that may underlie susceptibility to metabolic dysregulation and associated pulmonary morbidity among children. Lastly, we identify knowledge gaps that need further exploration to better define pathways that will allow development of primary preventive strategies for obesity-related asthma in children.

Acute Ozone-Induced Pulmonary and Systemic Metabolic Effects Are Diminished in Adrenalectomized Rats

Acute ozone exposure increases circulating stress hormones and induces metabolic alterations in animals. We hypothesized that the increase of adrenal-derived stress hormones is necessary for both ozone-induced metabolic effects and lung injury. Male Wistar-Kyoto rats underwent bilateral adrenal demedullation (DEMED), total bilateral adrenalectomy (ADREX), or sham surgery (SHAM). After a 4 day recovery, rats were exposed to air or ozone (1 ppm), 4 h/day for 1 or 2 days and responses assessed immediately postexposure. Circulating adrenaline levels dropped to nearly zero in DEMED and ADREX rats relative to SHAM. Corticosterone tended to be low in DEMED rats and dropped to nearly zero in ADREX rats. Adrenalectomy in air-exposed rats caused modest changes in metabolites and lung toxicity parameters. Ozone-induced hyperglycemia and glucose intolerance were markedly attenuated in DEMED rats with nearly complete reversal in ADREX rats. Ozone increased circulating epinephrine and corticosterone in SHAM but not in DEMED or ADREX rats. Free fatty acids (P = .15) and branched-chain amino acids increased after ozone exposure in SHAM but not in DEMED or ADREX rats. Lung minute volume was not affected by surgery or ozone but ozone-induced labored breathing was less pronounced in ADREX rats. Ozone-induced increases in lung protein leakage and neutrophilic inflammation were markedly reduced in DEMED and ADREX rats (ADREX > DEMED). Ozone-mediated decreases in circulating white blood cells in SHAM were not observed in DEMED and ADREX rats. We demonstrate that ozone-induced peripheral metabolic effects and lung injury/inflammation are mediated through adrenal-derived stress hormones likely via the activation of stress response pathway.

Glucagon induces airway smooth muscle relaxation by nitric oxide and prostaglandin E₂

Glucagon is a hyperglycemic pancreatic hormone that has been shown to provide a beneficial effect against asthmatic bronchospasm. We investigated the role of this hormone on airway smooth muscle contraction and lung inflammation using both in vitro and in vivo approaches. The action of glucagon on mouse cholinergic tracheal contraction was studied in a conventional organ bath system, and its effect on airway obstruction was also investigated using the whole-body pletysmographic technique in mice. We also tested the effect of glucagon on lipopolysaccharide (LPS)-induced airway hyperreactivity (AHR) and inflammation. The expression of glucagon receptor (GcgR), CREB, phospho-CREB, nitric oxide synthase (NOS)-3, pNOS-3 and cyclooxygenase (COX)-1 was evaluated by western blot, while prostaglandin E₂ (PGE₂) and tumour necrosis factor-α were quantified by enzyme-linked immunoassay and ELISA respectively. Glucagon partially inhibited carbachol-induced tracheal contraction in a mechanism clearly sensitive to des-His1-[Glu9]-glucagon amide, a GcgR antagonist. Remarkably, GcgR was more expressed in the lung and trachea with intact epithelium than in the epithelium-denuded trachea. In addition, the glucagon-mediated impairment of carbachol-induced contraction was prevented by either removing epithelial cells or blocking NOS (L-NAME), COX (indomethacin) or COX-1 (SC-560). In contrast, inhibitors of either heme oxygenase or COX-2 were inactive. Intranasal instillation of glucagon inhibited methacholine-induced airway obstruction by a mechanism sensitive to pretreatment with L-NAME, indomethacin and SC-560. Glucagon induced CREB and NOS-3 phosphorylation and increased PGE₂ levels in the lung tissue without altering COX-1 expression. Glucagon also inhibited LPS-induced AHR and bronchoalveolar inflammation. These findings suggest that glucagon possesses airway-relaxing properties that are mediated by epithelium-NOS-3-NO- and COX-1-PGE₂-dependent mechanisms.

A short review of adipokines, smooth muscle and uterine contractility

Obesity is a major health problem worldwide. The prevalence of obesity is increasing in both developed and developing countries. In the UK, for example, 60% of adults are overweight and 25% are obese. Obesity is associated with many pathological complications including respiratory, cardiovascular and endocrine, but it also affects fertility and is associated with many reproductive complications. This has led us and others to investigate links between women with high BMI, pregnancy outcome and uterine function. These studies in turn have led investigators to ask how obesity can have such an impact on reproduction and, as part of this, to consider the role of the adipokines released from adipose tissues. Our focus in this short review is on adipokines and myometrial activity, and for completeness we overview their effects on other smooth muscles. To date four adipokines (leptin, visfatin, apelin and ghrelin) have been investigated and all affect myometrial contractility, but some more potently than others. We consider the possible mechanisms involved in how adipokines may modify uterine contractility, and discuss the potential impact on labor and delivery.