Effect of an inhaled glucocorticosteroid on airway mucosal blood flow in mild asthma

Interleukin-17A and vascular remodelling in severe asthma; lack of evidence for a direct role

BACKGROUND

Bronchial vascular remodelling may contribute to the severity of airway narrowing through mucosal congestion. Interleukin (IL)-17A is associated with the most severe asthmatic phenotype but whether it might contribute to vascular remodelling is uncertain.

OBJECTIVE

To assess vascular remodelling in severe asthma and whether IL-17A directly or indirectly may cause endothelial cell activation and angiogenesis.

METHODS

Bronchial vascularization was quantified in asthmatic subjects, COPD and healthy subjects together with the number of IL-17A⁺ cells as well as the concentration of angiogenic factors in the sputum. The effect of IL-17A on in vitro angiogenesis, cell migration and endothelial permeability was assessed directly on primary human lung microvascular endothelial cells (HMVEC-L) or indirectly with conditioned medium derived from normal bronchial epithelial cells (NHBEC), fibroblasts (NHBF) and airway smooth muscle cells (ASMC) after IL-17A stimulation.

RESULTS

Severe asthmatics have increased vascularity compared to the other groups, which correlates positively with the concentrations of angiogenic factors in sputum. Interestingly, we demonstrated that increased bronchial vascularity correlates positively with the number of subepithelial IL-17A⁺ cells. However IL-17A had no direct effect on HMVEC-L function but it enhanced endothelial tube formation and cell migration through the production of angiogenic factors by NHBE and ASMC.

CONCLUSIONS & CLINICAL RELEVANCE

Our results shed light on the role of IL-17A in vascular remodelling, most likely through stimulating the synthesis of other angiogenic factors. Knowledge of these pathways may aid in the identification of new therapeutic targets.

A novel modelling approach to energy transport in a respiratory system

In this paper, energy transport in a respiratory tract is modelled using the finite element method for the first time. The upper and lower respiratory tracts are approximated as a 1-dimensional domain with varying cross-sectional and surface areas, and the radial heat conduction in the tissue is approximated using the 1-dimensional cylindrical coordinate system. The governing equations are solved using 1-dimensional linear finite elements with convective and evaporative boundary conditions on the wall. The results obtained for the exhalation temperature of the respiratory system have been compared with the available animal experiments. The study of a full breathing cycle indicates that evaporation is the main mode of heat transfer, and convection plays almost negligible role in the energy transport. This is in-line with the results obtained from animal experiments.

Tracheobronchopathy From Inhaled Corticosteroids

Inhaled corticosteroids (ICSs) have become the mainstay of asthma control. They are also recommended as an add-on therapy to long-acting beta agonists and anticholinergics in moderate to severe COPD with recurrent exacerbations. Ultimately this clinical practice has led to the widespread use of ICSs, which are supported by a more favorable side effect profile than that of systemic steroids.

The role of the endothelium in asthma and chronic obstructive pulmonary disease (COPD)

COPD and asthma are important chronic inflammatory disorders with a high associated morbidity. Much research has concentrated on the role of inflammatory cells, such as the neutrophil, in these diseases, but relatively little focus has been given to the endothelial tissue, through which inflammatory cells must transmigrate to reach the lung parenchyma and cause damage. There is evidence that there is an abnormal amount of endothelial tissue in COPD and asthma and that this tissue and its’ progenitor cells behave in a dysfunctional manner. This article reviews the evidence of the involvement of pulmonary endothelium in COPD and asthma and potential treatment options for this.

Oscillations of Skin Microvascular Blood Flow in Patients with Asthma

OBJECTIVE

This research is aimed at studying the features of skin blood flow oscillations in patients with severe persistent atopic BA during a period of fine control over symptoms.

METHODS

The study of microcirculation was carried out by LDF at rest and in response to a transient ischemia in 20 patients. The time-amplitude adaptive wavelet analysis of the blood flow oscillations was conducted to elucidate the peculiarities of microcirculatory regulation system functioning.

RESULTS

No significant changes were revealed for SBP and the oscillation amplitudes in the cardiac (0.6-2 Hz) and respiratory (0.145-0.6 Hz) intervals, both at rest and in response to transient ischemia, in patients compared to the control group. A consistent twofold decrease in the oscillation amplitudes was found in the neurogenic (0.021-0.052 Hz) interval at rest, as well as in the myogenic (0.052-0.145 Hz) and NO-dependent endothelial (0.0095-0.021 Hz) intervals both at rest and during the postocclusive reactive hyperemia in patients with lung obstruction (FEV1 < 80%) in comparison with a control group.

CONCLUSIONS

The amplitudes of skin blood flow oscillations in the myogenic, neurogenic and NO-dependent endothelial intervals in patients with obstruction are different from those in patients without obstruction.

Tracheobronchial smooth muscle atrophy and separation

We report a case series involving 4 patients with chronic obstructive pulmonary disease who were on an appropriate medical regimen including a high dose of inhaled corticosteroids (ICS). During bronchoscopy, patients were found to have an excessive dynamic collapse of the posterior wall and its separation from the ends of the adjacent cartilaginous rings. This was causing a near-total occlusion of the tracheal and bronchial lumen during exhalation, thereby presenting with an obstructive pattern on the pulmonary functions. We suspect that this was caused by the atrophy of the smooth muscles of the tracheobronchial wall. We reviewed the literature to explore the mechanisms causing atrophy of the bronchial smooth muscle, focusing on the potential role of long-term ICS use.

Immediate antiinflammatory effects of inhaled budesonide in patients with asthma

BACKGROUND

In patients with asthma, single doses of inhaled glucocorticosteroids (ICS) have been reported to have antiinflammatory actions that can be detected several hours after drug administration. However, the onset and duration of the effect have not been investigated. We therefore measured airway blood flow ([Formula: see text]aw) as an index of airway inflammation to determine the time course and dose dependence of the antiinflammatory action of an ICS in 20 patients with moderate asthma receiving regular ICS treatment.

METHODS

[Formula: see text]aw and spirometry were measured before and serially for 360 minutes after a single inhaled dose of 360 μg, 720 μg, and 1,440 μg budesonide or placebo as well as after four repetitive 720-μg budesonide doses given 30 minutes apart.

RESULTS

Baseline mean [Formula: see text]aw was increased and FEV1 was decreased without significant differences among the 5 treatment days. After budesonide inhalation, there was a transient, dose-dependent decrease in mean [Formula: see text]aw from 12 to 21%, with significant differences from baseline at 60 and 90 minutes for the 720-μg and 1,440-μg doses (P < 0.05). Thirty minutes after four repetitive budesonide administrations, mean [Formula: see text]aw was 28% below baseline (P < 0.05) and remained 11% below baseline after 270 minutes. There was no change in mean FEV1 after any of the treatments.

CONCLUSIONS

In subjects with moderate asthma who use ICS regularly, inhaled budesonide caused a transient dose-dependent vasoconstriction in the airway, thereby reversing one manifestation of airway inflammation. These results suggest that a pure controller medication can have immediate beneficial effects not paralleled by changes in airflow. Clinical trial registered with www.clinicaltrials.gov (NCT 01219738).

Inhaled corticosteroid treatment modulates ZNF432 gene variant's effect on bronchodilator response in asthmatics

BACKGROUND

Single nucleotide polymorphisms (SNPs) influence a patient's response to inhaled corticosteroids and β2-agonists, and the effect of treatment with inhaled corticosteroids is synergistic with the effect of β2-agonists. We hypothesized that use of inhaled corticosteroids could influence the effect of SNPs associated with a bronchodilator response.

OBJECTIVE

To assess whether, among subjects with asthma, the association of SNPs with bronchodilator response is different between those treated with inhaled corticosteroids versus those on placebo.

METHODS

A genome-wide association analysis was conducted by using 581 white subjects from the Childhood Asthma Management Program. By using data for 449,540 SNPs, we conducted a gene by environment analysis in PLINK with inhaled corticosteroid treatment as the environmental exposure and bronchodilator response as the outcome measure. We attempted to replicate the top 12 SNPs in the Leukotriene Modifier or Corticosteroid or Corticosteroid-Salmeterol Trial.

RESULTS

The combined P value for the Childhood Asthma Management Program and Leukotriene Modifier or Corticosteroid or Corticosteroid-Salmeterol Trial populations was 4.8 × 10(-8) for rs3752120, which is located in the zinc finger protein gene ZNF432 and has an unknown function.

CONCLUSIONS

Inhaled corticosteroids appear to modulate the association of bronchodilator response with variant(s) in the ZNF432 gene among adults and children with asthma.

Role of Inhaled Steroids in Vascular Airway Remodelling in Asthma and COPD

In chronic obstructive airway diseases, such as asthma and chronic obstructive pulmonary disease (COPD), changes in bronchial microvasculature are present in response to inflammatory stimuli. Vascular changes may significantly contribute to airway wall remodelling. Angiogenesis and vascular leakage are prevalent in asthma, while vasodilation and vascular leakage dominate in COPD. An endothelial dysfunction may be present both in asthma and in COPD. Vascular changes may occur simultaneously with the thickening of the airway wall and the narrowing of the bronchial lumen. Consequently, pharmacological control of bronchial vascular remodelling may be crucial for symptom control in asthma and COPD. In asthmatic airways, inhaled steroids can downregulate vascular remodelling by acting on proangiogenic factors. Additionally, studies on combination therapy with long-acting β2-agonists and inhaled steroids have provided evidence of a possible synergistic action on components of vascular remodelling in asthma. In COPD, there is less experimental evidence on the effect of inhaled steroids on airway microvascular changes. Importantly, vascular endothelial growth factor (VEGF), the most specific growth factor for vascular endothelium, is crucially involved in the pathophysiology of airway vascular remodelling, both in asthma and COPD. The inhibition of VEGF and its receptor may be useful in the treatment of the vascular changes in the airway wall.

Acute effects of salmeterol and fluticasone propionate alone and in combination on airway blood flow in patients with asthma

BACKGROUND

The airway contains airway smooth muscle and airway vascular smooth muscle. The acute effects of inhaled long-acting β(2)-adrenergic agonists (LABAs) alone, or in combination with an inhaled glucocorticoid (ICS), on airway smooth muscle tone in asthma are known; however, to the best of our knowledge, their effect on airway vascular smooth muscle tone has not been investigated previously. The objective of this study was to investigate the immediate effects of a LABA and an ICS alone and in combination on airway blood flow (Qaw) as an index of airway vascular smooth muscle tone in patients with stable asthma.

METHODS

Fourteen subjects with moderate asthma inhaled single doses of salmeterol (50 μg), fluticasone propionate (250 μg), salmeterol/fluticasone propionate (50/250 μg), or placebo; Qaw was measured before and serially for 240 min after drug administration.

RESULTS

Mean Qaw increased after salmeterol and salmeterol/fluticasone propionate, with peaks at 60 min of 34% and 40%, respectively, and returned to baseline by 240 min after inhalation. Fluticasone propionate alone caused a transient decrease in mean Qaw. The maximal changes in Qaw, which occurred at different times, were 60% for salmeterol, 67% for salmeterol/fluticasone propionate, and -19% for fluticasone propionate (P < .05 vs placebo for all).

CONCLUSIONS

The LABA salmeterol has an acute vasodilator action on the airway of subjects with stable asthma. The addition of fluticasone propionate, which by itself causes vasoconstriction, does not attenuate the salmeterol-induced vasodilation, suggesting that fluticasone propionate potentiates the vasodilator effect of salmeterol. The vasodilation could be of clinical benefit by promoting the vascular clearance of inflammatory mediators including spasmogens from the airway.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT01231230; URL: www.clinicaltrials.gov.

Genomic and non-genomic actions of glucocorticoids in asthma

Glucocorticoids are the mainstay of asthma therapy. They are primarily used to suppress airway inflammation, which is the central pathological change in asthmatic patients’ airways. This is achieved by many different mechanisms. The classical mechanism is by suppression of the genetic transcription of many inflammatory cytokines that are key in asthma pathophysiology (transrepression). On the other hand, the transcription of certain inhibitory cytokines is activated by glucocorticoids (transactivation), a mechanism that also mediates many of the adverse effects of glucocorticoids. The onset of action through these mechanisms is often delayed (4-24 hours). Other mechanisms mediated through non-genomic pathways are increasingly appreciated. These are delivered in part by binding of glucocorticoids to nonclassical membrane-bound glucocorticoid receptors or by potentiating the α1-adrenergic action on the bronchial arterial smooth muscles, in addition to other mechanisms. These effects are characterized by their rapid onset and short duration of action. Understanding these different mechanisms will help in the development of new and better drugs to treat this common disease and to develop new improved strategies in our approach to its management. Here, the genomic and non-genomic mechanisms of actions of glucocorticoids in asthma are briefly reviewed, with special emphasis on the current updates of the non-genomic mechanisms.

Airway endothelial dysfunction in asthma and chronic obstructive pulmonary disease: a challenge for future research

Endothelial dysfunction in the extrapulmonary circulation has been linked to cardiovascular disease. Recent investigations have revealed that in the airway circulation, cigarette smoking, chronic obstructive pulmonary disease (COPD), and asthma are also accompanied by endothelial dysfunction. Inhaled glucocorticosteroids can partially or fully restore normal endothelium-dependent vasodilation in these conditions, thereby identifying the airway endothelium as a novel therapeutic target in the treatment of airway disease. The role of the defective endothelium-dependent vasodilation in the pathophysiology in asthma and COPD is still subject to speculation. However, there appears to be an association between COPD and extrapulmonary vascular dysfunction, and the possibility exists that the use of inhaled glucocorticosteroids has a beneficial effect on cardiovascular disease in COPD as suggested by database studies showing that inhaled glucocorticosteroids reduce the incidence of nonfatal and fatal cardiovascular events in COPD.

The bronchial circulation--worth a closer look: a review of the relationship between the bronchial vasculature and airway inflammation

Until recently, the bronchial circulation has been relatively ignored in the research and clinical arenas, perhaps because of its small volume and seeming dispensability relative to the pulmonary circulation. Although the bronchial circulation only receives around 1% of the cardiac output in health, it serves functions that are critical to maintaining airway and lung function. The bronchial circulation also plays an important role in many lung and airway diseases; through its ability to increase in size, the bronchial circulation is able to provide lung parenchymal perfusion when the pulmonary circulation is compromised, and more recently the role of the bronchial circulation in the pathogenesis of inflammatory airway disease has been explored. Due to the anatomic variability and small volume of the bronchial circulation, much of the research to date has necessitated the use of animal models and invasive procedures. More recently, non-invasive techniques for measuring bronchial blood flow in the mucosal microvascular network have been developed and offer a new avenue for the study of this circulation in humans. In conjunction with molecular research, measurement of airway blood flow (Q(aw)) may help elucidate the role of the bronchial circulation in inflammatory airway disease and become a useful tool for monitoring therapy.

Relationships between cortisol level, mortality and chronic diseases in older persons

CONTEXT

High cortisol level is known to be associated with osteoporosis, hypertension, diabetes mellitus (DM), susceptibility to infections and depression and may protect against chronic obstructive pulmonary disease.

OBJECTIVE

This study assesses the association between cortisol level, 6- to 7.5-year mortality risk and prevalence of chronic diseases.

DESIGN/SETTING/PARTICIPANTS

Subjects were selected from the Longitudinal Aging Study Amsterdam, an ongoing multidisciplinary cohort study in a general population of older persons (>/=65 years). Serum cortisol was measured in 1181 men and women in 1995/1996 (second cycle) and salivary cortisol in 998 men and women in 2001/2002 (fourth cycle).

MAIN OUTCOME MEASURES

Six to seven and a half year mortality and prevalence of chronic diseases.

RESULTS

Men with high salivary morning cortisol had a higher mortality risk than men with low levels [hazard ratio (HR) = 1.63, P = 0.04 for the third vs. the lowest tertile]. Women with high salivary evening cortisol had a higher mortality risk than women with low levels (HR = 1.82, P = 0.04 for the third vs. the lowest tertile). In men, high serum cortisol was independently associated with chronic nonspecific lung disease (CNSLD): odds ratio (OR) = 0.72, P < 0.01; hypertension: OR = 1.38, P < 0.01; DM: OR = 1.38, P = 0.02. In women, high salivary evening cortisol was independently associated with DM: OR = 1.33, P = 0.01 and CNSLD: OR = 0.58, P = 0.02. No independent association between cortisol and number of chronic diseases was found.

CONCLUSION

High salivary cortisol levels are associated with increased mortality risk in a general older population. High cortisol levels are associated with higher risks of hypertension and DM and lower risk of CNSLD.

Inhaled corticosteroids as combination therapy with beta-adrenergic agonists in airways disease: present and future

Inhaled corticosteroid (ICS) therapy in combination with long-acting beta-adrenergic agonists represents the most important treatment for chronic airways diseases such as asthma and chronic obstructive pulmonary disease (COPD). ICS therapy forms the basis for treatment of asthma of all severities, improving asthma control, lung function and preventing exacerbations of disease. Use of ICS has also been established in the treatment of COPD, particularly symptomatic patients, who experience useful gains in quality of life, likely from an improvement in symptoms such as breathlessness and in reduction in exacerbations, and an attenuation of the yearly rate of deterioration in lung function. The addition of long-acting beta-agonist (LABA) therapy with ICS increases the efficacy of ICS effects in moderate-to-severe asthma. Thus, a 800 mug daily dose of the ICS budesonide reduced severe exacerbation rates by 49% compared to a low dose of 200 mug daily, and addition of the LABA formoterol to budesonide (800 mug) led to a 63% reduction. In COPD, the effects of ICS are less prominent but there are beneficial effects on the decline in FEV(1) and the rate of exacerbations. A reduction in the rate of decline in FEV(1) of 16 ml/year with a 25% reduction in exacerbation rate has been reported with the salmeterol and fluticasone combination. A non-significant 17.5% reduction in all-cause mortality rate with ICS and LABA is reported. Chronic inflammation is a feature of both asthma and COPD, although there are site and characteristic differences. ICS targets this inflammation although this effect of ICS is less effective in patients with severe asthma and with COPD; however, addition of LABA may potentiate the anti-inflammatory effects of ICS. An important consideration is the presence of corticosteroid insensitivity in these patients. Currently available ICS have variably potent binding activities to specific glucocorticoid receptors, leading to inhibition of gene expression by either binding to DNA and inducing anti-inflammatory genes or by repressing the induction of pro-inflammatory mediators. Local side effects of ICS include oral candidiasis, hoarseness and dysphonia, while systemic side effects, such as easy bruising and reduction in growth velocity or bone mineral densitometry, are usually restricted to doses above maximally recommended doses. Use of LABA alone in patients with asthma increases the risk of asthma-related events including deaths, but this is less observed with the combination of ICS and LABA. Therefore, use of LABA alone is not recommended for asthma therapy. Future progress in ICS development will be characterised by the introduction of ICS with greater efficacy with a limited side-effect profile, and by longer-acting ICS that can be used in combination with once-daily LABAs. Other agents that could improve the efficacy of corticosteroids or reverse corticosteroid insensitivity may be added to ICS. ICS in combination with LABAs will continue to remain the main focus of treatment of airways diseases.

Rapid corticosteroid effect on beta(2)-adrenergic airway and airway vascular reactivity in patients with mild asthma

BACKGROUND

Long-term glucocorticoid therapy has been suggested to improve airway and airway vascular smooth muscle responsiveness to inhaled beta(2)-agonists in patients with asthma.

OBJECTIVE

We sought to assess whether a single dose of an inhaled glucocorticoid acutely potentiates beta(2)-adrenergic airway and airway vascular smooth muscle reactivity in asthma.

METHODS

In 10 asthmatic and 10 healthy subjects, airway blood flow and FEV(1) were measured before and 30 minutes after fluticasone or placebo inhalation and 15 minutes after the subsequent inhalation of racemic albuterol (0.6 mg or 1.25 mg) or (R)-albuterol (0.3 mg or 0.6 mg).

RESULTS

In healthy subjects all albuterol formulations increased airway blood flow equally after placebo or fluticasone pretreatment. In asthmatic subjects airway blood flow response was blunted after placebo and acutely restored after fluticasone pretreatment. Fluticasone pretreatment did not increase FEV(1) responses to any albuterol formulation, except 0.6 mg racemic albuterol.

CONCLUSION

A single dose of an inhaled glucocorticoid restores beta(2)-adrenergic airway vasodilator responses in patients with mild asthma. The mechanism of this rapid glucocorticoid effect remains to be clarified.

Acute severe asthma

Acute severe asthma remains a major economic and health burden. The natural history of acute decompensations is one of resolution and only about 0.4% of patients succumb overall. Mortality in medical intensive care units is higher but is less than 3% of hospital admissions. "Near-fatal" episodes may be more frequent, but precise figures are lacking. However, about 30% of medical intensive care unit admissions require intubation and mechanical ventilation with mortality of 8%. Morbidity and mortality increase with socioeconomic deprivation and ethnicity. Seventy to 80% of patients in emergency departments clear within 2 hours with standardized care. The relapse rate varies between 7 and 15%, depending on how aggressively the patient is treated. The airway obstruction in the 20-30% of people resistant to adrenergic agonists in the emergency department slowly reverses over 36-48 hours but requires intense treatment to do so. Current therapeutic options for this group consist of ipratropium and corticosteroids in combination with beta2 selective drugs. Even so, such regimens are not optimal and better approaches are needed. The long-term prognosis after a near-fatal episode is poor and mortality may approach 10%.

Asthma remission in a patient with rheumatoid arthritis while on antiangiogenesis therapy during a rheumatoid arthritis trial demonstrated by forced oscillation and spirometry

Asthma is a chronic inflammatory condition. An integral part of the inflammation is angiogenesis (neovascularization). This report describes a patient with rheumatoid arthritis (RA) and moderately severe asthma despite maintenance on inhaled corticosteroids (ics) and intermittent systemic steroids (ss). While enrolled in a clinical trial for RA employing MEDI-522 (Vitaxin), her asthma symptoms remitted substantially, with significant improvement in spirometry and airflow resistance measured by forced oscillation. The patient was able to discontinue ics and required no ss while taking MEDI-522. After termination of the clinical trial, the patient's asthma symptoms again increased and required reinstitution of ics for control.

Normal bronchial blood flow in COPD is unaffected by inhaled corticosteroids and correlates with exhaled nitric oxide

BACKGROUND

In COPD patients, there is reduced vascularity and inflammation of the bronchi, which may have opposite effects on bronchial blood flow (QAW). We studied the relationship of QAW with the fraction of exhaled nitric oxide (FENO), which is a potent vasodilator. We also investigated the vascular response to budesonide and a beta(2)-agonist.

METHODS

We measured QAW in 17 patients with COPD (mean [+/- SEM] age, 67 +/- 3 years; 10 male patients; mean FEV(1), 57 +/- 3% predicted; mean FEV(1)/FVC ratio, 54 +/- 4%), all of whom were ex-smokers, and in 16 age-matched nonsmoking volunteers (mean age, 64 +/- 4 years) and compared this to FENO. QAW was measured using the acetylene dilution method.

RESULTS

Mean QAW was similar in patients with COPD (34.29 +/- 1.09 microL/mL/min) compared to healthy subjects (35.50 +/- 1.74 microL/mL/min; p > 0.05) and was not affected by long-term treatment (35.89 +/- 1.63 microL/mL/min) or short-term treatment (32.50 +/- 1.24 microL/mL/min; p < 0.05) with inhaled budesonide. QAW positively correlated with the diffusion of carbon monoxide (ie, carbon monoxide transfer coefficient: r = 0.74; p < 0.05). FENO levels were mildly elevated in steroid-treated patients (10.89 +/- 0.87 parts per billion [ppb]) and untreated patients (9.40 +/- 0.86 ppb) compared to the control group (8.22 +/- 0.57 ppb; p < 0.05) and were correlated with QAW (r = 0.6; p < 0.05). Ten minutes after the inhalation of 200 microg of albuterol, QAW was more elevated in healthy control subjects (59.33 +/- 2.40 microL/mL/min) compared to COPD patients (38.00 +/- 0.58 microL/mL/min; p < 0.05), indicating that COPD patients may have a reduced bronchial vascular reactivity.

CONCLUSIONS

QAW is normal in COPD patients and is not affected by therapy with inhaled corticosteroids or beta(2)-agonists. In addition, QAW correlates with levels of FENO, which may have a regulatory role.

A simplified noninvasive method to measure airway blood flow in humans

Our laboratory has previously developed and validated a noninvasive soluble gas uptake method to measure airway blood flow (Qaw) in humans (Onorato DJ, Demirozu MC, Breitenbücher A, Atkins ND, Chediak AD, and Wanner A. Am J Respir Crit Care Med 149: 1132-1137, 1994; Scuri M, McCaskill V, Chediak AD, Abraham WM, and Wanner A. J Appl Physiol 79: 1386-1390, 1995). The method has the disadvantage of requiring eight breath-hold maneuvers for a single Qaw measurement, a complicated data analysis, and the inhalation of a potentially explosive gas mixture containing dimethylether (DME) and O2. Because of these shortcomings, the method thus far has not been used in other laboratories. We now simplified the method by having the subjects inhale 500 ml of a 10% DME-90% N2 gas mixture to fill the anatomical dead space, followed by a 5- or 15-s breath hold, and measuring the instantaneous DME and N2 concentrations and volume at the airway opening during the subsequent exhalation. From the difference in DME concentration in phase 1 of the expired N2 wash-in curve multiplied by the phase 1 dead space volume and divided by the mean DME concentration and the solubility coefficient for DME in tissue, Qaw can be calculated by using Fick's equation. We compared the new method to the validated old method in 10 healthy subjects and found mean +/- SE Qaw values of 34.6 +/- 2.3 and 34.6 +/- 2.8 microl.min(-1).ml(-1), respectively (r = 0.93; upper and lower 95% confidence limit +2.48 and -2.47). Using the new method, the mean coefficient of variation for two consecutive measurements was 4.4% (range 0-10.4%); inhalation of 1.2 mg albuterol caused a 53 +/- 14% increase in Qaw (P = 0.02) and inhalation of 2.4 mg methoxamine caused a 32 +/- 7% decrease in Qaw (P = 0.07). We conclude that the new method provides reliable values of and detects the expected changes in Qaw with vasoactive drugs. The simplicity and improved safety of the method should improve its acceptability for the noninvasive assessment of Qaw in clinical research.

Airway blood flow reactivity in healthy smokers and in ex-smokers with or without COPD

STUDY OBJECTIVES

Cigarette smoking has been associated with impaired endothelium-dependent relaxation responses in the brachial and coronary arteries (endothelial dysfunction). The aim of the present study was to determine whether the airway circulation is also affected and whether pharmacologic treatment has an effect on endothelial function in patients with COPD.

METHODS AND PATIENTS

Airway blood flow (Qaw) responses to therapy with inhaled albuterol, which causes endothelium-dependent vasodilation, were measured with a noninvasive soluble-gas-uptake technique in age-matched healthy current smokers (n = 10), healthy ex-smokers (n = 10), ex-smokers with COPD (n = 10), and healthy lifetime nonsmokers. In the ex-smokers with COPD, the albuterol responsiveness measurement was repeated after 4 weeks of treatment with fluticasone/salmeterol and after a drug washout period of 4 or 8 weeks.

RESULTS

The mean (+/- SE) baseline Qaw values ranged between 40.7 +/- 3.9 and 50.9 +/- 2.8 microL/min/mL anatomic dead space in the four groups (differences were not significant). The mean FEV(1) was 53.4 +/- 2.3% predicted in the ex-smokers with COPD. Albuterol inhalation increased mean Qaw significantly in lifetime nonsmokers (50.1 +/- 8.3% predicted; p < 0.05) and healthy ex-smokers (37.2 +/- 3.4% predicted; p < 0.05), but not in healthy current smokers (13.9 +/- 3.2% predicted; difference was not significant) and ex-smokers with COPD (9.7 +/- 4.5% predicted; difference was not significant). While fluticasone/salmeterol did not change Qaw significantly, it restored albuterol responsiveness (67.6 +/- 11.1% predicted; p < 0.05) in the ex-smokers with COPD; this effect was no longer seen after the drug washout period.

CONCLUSIONS

Cigarette smoking is associated with a blunted vasodilator response to inhaled albuterol in the airway as an expression of endothelial dysfunction, with a partial recovery of albuterol responsiveness after smoking cessation in healthy ex-smokers but not in ex-smokers with COPD. In the latter group, combined glucocorticoid/long-acting beta(2)-adrenergic agonist treatment restores albuterol responsiveness. The role of endothelial dysfunction in the physiopathology of COPD remains to be examined.

Inhaled corticosteroids reduce asthma-associated airway hyperperfusion through genomic and nongenomic mechanisms

Inhaled corticosteroids have both genomic and nongenomic actions on the tracheobronchial (airway) vasculature in patients with bronchial asthma. Genomic actions involve the activation or repression of target genes associated with inflammation, and reduce inflammatory hyperperfusion in the airway. In contrast, nongenomic actions are mediated by rapid cellular mechanisms, and induce transient vasoconstriction. This article reviews recent progress on the mechanisms by which inhaled corticosteroids reverse inflammatory blood flow changes in the airway in asthma.

Airway blood flow reactivity in smokers

Cigarette smoking has been associated with impaired endothelium-dependent relaxation responses in the brachial and coronary arteries (endothelial dysfunction). The aim of the present study was to determine if the airway circulation is also affected and if airway treatment has an effect on endothelial function. Airway blood flow (Q(aw)) responses to inhaled albuterol as an index of endothelial function were measured in age-matched healthy current smokers, healthy ex-smokers, ex-smokers with COPD and healthy lifetime non-smokers; in the ex-smokers with COPD, the albuterol responsiveness was repeated after a 4-week treatment with an inhaled glucocorticoid/beta(2)-adrenergic agonist combination drug. Mean baseline Q(aw) was similar in the four groups. Albuterol inhalation increased mean Q(aw) in lifetime non-smokers (50.1+/-8.3%; p<0.05) and in healthy ex-smokers (37.2+/-3.4%; p<0.05) but not in healthy current smokers (13.9+/-3.2%; p=NS) and ex-smokers with COPD (9.7+/-4.5%; p=NS). While drug treatment per se did not change Q(aw) significantly, it restored albuterol responsiveness (+67.6+/-11.1%; p<0.05) in the ex-smokers with COPD. Thus, cigarette smoking is associated with endothelial dysfunction in the airway, with a partial recovery of endothelial function after smoking cessation in healthy ex-smokers but not in ex-smokers with COPD. In the latter, combined glucocorticoid/beta(2)-adrenergic agonist treatment restores albuterol responsiveness.

Correlation of exhaled breath temperature with bronchial blood flow in asthma

In asthma elevated rates of exhaled breath temperature changes (Δe°T) and bronchial blood flow (Q_aw) may be due to increased vascularity of the airway mucosa as a result of inflammation.

We investigated the relationship of Δe°T with Q_aw and airway inflammation as assessed by exhaled nitric oxide (NO). We also studied the anti-inflammatory and vasoactive effects of inhaled corticosteroid and β₂-agonist.

Δe°T was confirmed to be elevated (7.27 ± 0.6 Δ°C/s) in 19 asthmatic subjects (mean age ± SEM, 40 ± 6 yr; 6 male, FEV₁ 74 ± 6 % predicted) compared to 16 normal volunteers (4.23 ± 0.41 Δ°C/s, p < 0.01) (30 ± 2 yr) and was significantly increased after salbutamol inhalation in normal subjects (7.8 ± 0.6 Δ°C/ s, p < 0.05) but not in asthmatic patients. Q_aw, measured using an acetylene dilution method was also elevated in patients with asthma compared to normal subjects (49.47 ± 2.06 and 31.56 ± 1.6 μl/ml/min p < 0.01) and correlated with exhaled NO (r = 0.57, p < 0.05) and Δe°T (r = 0.525, p < 0.05). In asthma patients, Q_aw was reduced 30 minutes after the inhalation of budesonide 400 μg (21.0 ± 2.3 μl/ml/min, p < 0.05) but was not affected by salbutamol.

Δe°T correlates with Q_aw and exhaled NO in asthmatic patients and therefore may reflect airway inflammation, as confirmed by the rapid response to steroids.

Effect of montelukast and fluticasone propionate on airway mucosal blood flow in asthma

Asthma is associated with an increase in airway blood flow (Qaw), presumably as a manifestation of airway inflammation. We therefore determined the effect of the antiinflammatory agents montelukast (ML) and fluticasone propionate (FP) on Qaw in 12 patients with mild intermittent asthma. Using a double-blind approach, Qaw along with FEV(1) and Vmax(50) were determined before and after a 2-week treatment period with either ML (10 mg/day), FP (440 microg/day), or 10 mg of ML plus 440 microg of FP daily, separated by 2-week washout periods. Mean (+/- SEM) Qaw ranged from 68 +/- 4.2 to 71.8 +/- 5.9 microl x minute(-1) x ml(-1) anatomic dead space before the treatment periods. ML, FP, and ML plus FP decreased mean Qaw by 21.5, 20.8, and 26.9%, respectively (p < 0.05 for all). No significant difference was observed among the three regimens. FEV(1) and Vmax(50) were not changed by any of the treatments. We conclude that at the dosages used, ML and FP are equipotent in reducing Qaw in patients with mild asthma, and that the magnitude of the response is not greater if the two drugs are combined. The results also suggest that the vascular effects of these agents can be assessed independent of their effects on airway function.

Pharmacology of airway inflammation in asthma and COPD

The current asthma therapies are not cures and symptoms return soon after treatment is stopped even after long term treatment. Although inhaled glucocorticoids are highly effective in controlling airway inflammation in asthma, they are ineffective in the small group of patients with glucocorticoid-dependent and -resistant asthma. With very few exceptions, COPD is caused by tobacco smoking, and smoking cessation is the only truly effective treatment of COPD available. Current pharmacological treatment of COPD is unsatisfactory, as it does not significantly influence the severity of the disease or its natural course. Glucocorticoids are scarcely effective in COPD patients without concomitant asthma. Bronchodilators improves symptoms and quality of life, in COPD patients, but, with the exception of tiotropium, they do not significantly influence the natural course of the disease. Theophylline is the only drug which has been demonstrated to have a significant effect on airway inflammation in patients with COPD. Here we review the pharmacology of currently used antiinflammatory therapies for asthma and COPD and their proposed mechanisms of action. Recent understanding of disease mechanisms in severe steroid-dependent and -resistant asthma and in COPD, has lead to the development of novel compounds, which are in various stages of clinical development. We review the current status of some of these new potential drugs.

Molecular targets for steroids in airway vascular smooth muscle

The actions of norepinephrine (NE) released from airway sympathetic nerves are partially terminated by the extraneuronal catecholamine uptake. Because various steroid hormones inhibit extraneuronal uptake, it could be responsible for the airway vasoconstriction caused by inhaled glucocorticosteroids (GSs) in vivo. Using bronchial arteries obtained from donor lungs rejected for transplantation, we showed that a plasma membrane-associated transporter is responsible for NE uptake by airway vascular smooth muscle. We identified this transporter, namely the extraneuronal monoamine transporter (EMT), by demonstrating its function and mRNA expression. Furthermore, we showed that the rapid, nongenomic inhibitory GS effect on EMT is likely mediated through the activation of specific K+ channels in the plasma membrane. We believe that our studies identified new molecular targets for GSs in modulating noradrenergic control of airway vascular tone.

Faster rise of exhaled breath temperature in asthma: a novel marker of airway inflammation?

In asthma there is increased vascularity of the airway mucosa, altering heat loss in the airways. We hypothesized that as a result of these inflammatory changes, asthmatic patients would have elevated rates of the exhaled air temperature increase (Deltae degrees T). We measured Deltae degrees T in 18 asthmatic subjects (mean age +/- SEM, 38 +/- 8 yr; 9 male, FEV(1) 74 +/- 10%) and 16 normal volunteers (mean age +/- SEM, 33 +/- 3 yr) and compared it with exhaled nitric oxide (NO) as a marker of inflammation. Deltae degrees T was measured during a flow- and pressure-controlled single exhalation with a fast response (1 ms) thermometer. The end-expiratory plateau temperature was similar in asthmatic compared with normal subjects (35.75 +/- 0.6 degrees C and 34.45 +/- 0.8 degrees C, p > 0.05). However, Deltae degrees T was greater in asthmatic subjects (8.17 +/- 0.83 degrees C/s and 4.12 +/- 0.41 degrees C/s, p < 0.01) and correlated with NO (r = 0.65, p = 0.034). Deltae degrees T was increased in normal subjects (from 4.28 +/- 0.8 degrees C/s to 7.60 +/- 0.5 degrees C/s, p < 0.01) but not in asthmatic patients (from 8.28 +/- 0.41 degrees C/s to 8.80 +/- 0.41 degrees C/s, p > 0.05) after the inhalation of albuterol, indicating that Deltae degrees T may reflect bronchial blood flow. Asthmatic subjects have elevated Deltae degrees T. This may represent a novel, noninvasive means of measuring airway blood flow and inflammation in asthma.

Steroid sensitivity of norepinephrine uptake by human bronchial arterial and rabbit aortic smooth muscle cells

We have shown that an inhaled glucocorticosteroid (GS) causes alpha(1)-adrenergic antagonist-blockable, rapid, and transient bronchial vasoconstriction in healthy and asthmatic subjects. Steroids inhibit norepinephrine (NE) uptake by non-neuronal cells, thereby increasing NE concentration at alpha-adrenergic receptor sites. This could explain the GS-induced bronchial vasoconstriction. We therefore studied expression of the steroid-sensitive extraneuronal monoamine transporter (EMT) and steroid sensitivity of NE uptake in human bronchial artery and rabbit aorta (as a substitute for the limited supply of human bronchial artery). NE uptake was measured using a semiquantitative, sucrose-potassium phosphate-glyoxylic acid fluorescence method that we newly adapted for use in single cells. Both human bronchial arteries and rabbit aorta expressed messenger RNA for EMT, and steroids blocked NE uptake into freshly dissociated human bronchial arterial and rabbit aortic smooth-muscle cells (SMCs). In the latter, inhibition of NE uptake by steroids was not altered, either by a protein synthesis inhibitor (cycloheximide) or by a transcription inhibitor (actinomycin D), and corticosterone made membrane-impermeant by conjugation to bovine serum albumin inhibited NE uptake equipotently. These data show that NE uptake into bronchial arterial and rabbit aortic SMCs is sensitive to steroids, possibly mediated by EMT, and suggest a mechanism for GS-induced bronchial vasoconstriction.

Fluticasone inhibits but does not reverse allergen-induced structural airway changes

Ethical and technical reasons limit the possibility of evaluating the effects of inhaled corticosteroids on structural changes in airways of humans with asthma. We therefore evaluated whether fluticasone propionate (FP) modifies airway remodeling, induced by repeated allergen exposure in rats. Sensitized BN rats were exposed to aerosolized ovalbumin (OA) for 2 wk. To assess the effect of FP on the development of or on established airway remodeling, animals were treated with aerosolized FP or placebo during allergen exposure or for 2 wk afterward. Compared with animals exposed to phosphate-buffered saline (PBS), OA-challenged animals developed an increase in total airway wall area, enhanced fibronectin deposition, epithelial cell proliferation, goblet cell hyperplasia, and airway hyperresponsiveness. Concomitant treatment with FP decreased all allergen-induced structural changes without being able to reverse them to normal. Initiating FP treatment after the allergen exposure had no effect on any of the OA-induced structural airway changes. The increase in total airway wall area, enhanced fibronectin deposition, and epithelial cell proliferation persisted. The goblet cell hyperplasia disappeared spontaneously. In conclusion, concomitant treatment with FP partly inhibits structural airway changes as well as hyperresponsiveness induced by OA exposure. Post hoc treatment fails to reverse established airway remodeling.

Adrenergic airway vascular smooth muscle responsiveness in healthy and asthmatic subjects

The purpose of the present study was to determine the responsiveness of airway vascular smooth muscle (AVSM) as assessed by airway mucosal blood flow (Qaw) to inhaled methoxamine (alpha(1)-agonist; 0.6-2.3 mg) and albuterol (beta(2)-agonist; 0.2-1.2 mg) in healthy [n = 11; forced expiratory volume in 1 s, 92 +/- 4 (SE) % of predicted] and asthmatic (n = 11, mean forced expiratory volume in 1 s, 81 +/- 5%) adults. Mean baseline values for Qaw were 43.8 +/- 0.7 and 54.3 +/- 0.8 microl. min(-1). ml(-1) of anatomic dead space in healthy and asthmatic subjects, respectively (P < 0.05). After methoxamine inhalation, the maximal mean change in Qaw was -13.5 +/- 1.0 microl. min(-1). ml(-1) in asthmatic and -7.1 +/- 2.1 microl. min(-1). ml(-1) in healthy subjects (P < 0.05). After albuterol, the mean maximal change in Qaw was 3.0 +/- 0.8 microl. min(-1). ml(-1) in asthmatic and 14.0 +/- 1.1 microl. min(-1). ml(-1) in healthy subjects (P < 0.05). These results demonstrate that the contractile response of AVSM to alpha(1)-adrenoceptor activation is enhanced and the dilator response of AVSM to beta(2)-adrenoceptor activation is blunted in asthmatic subjects.