Exhaled nitric oxide in the diagnosis and management of asthma

Ability of Exhaled Nitric Oxide to Discriminate for Airflow Obstruction Among Frequent Exacerbators of Clinically Diagnosed Asthma

OBJECTIVE

Fraction of exhaled nitric oxide (FE_NO) has been proposed as a non-invasive biomarker for allergic inflammation seen in asthma. Many asthmatics in clinical practice have never had spirometry and recent data report misdiagnoses in patients with physician diagnosed (PD) asthma. The aim of this study was to assess the ability of FE_NO to discriminate between those with and without airflow obstruction (AO) among patients with PD-asthma.

METHODS

Frequent exacerbators of PD-asthma (with 2 or more asthma exacerbations leading to emergency room visit or hospitalization within last 12 months) were enrolled. All patients underwent diagnostic evaluations including spirometry, FE_NO testing and serum immunoglobulin (IgE) and eosinophils. Serial spirometry and methacholine challenge testing (MCT) were performed as indicated. AO was defined by a decreased FEV1/FVC ratio (< 70% and/or < LLN), or a positive MCT.

RESULTS

Of the 222 patients with PD-asthma, AO was found in 136 (vs. 86 without AO). 81.6% of patients with AO and 66.2% without AO completed FE_NO testing. There was no significant difference in the mean FE_NO levels among patients with or without AO (40.8 vs. 30.4 ppb, P = 0.10). Likewise, there was no difference in the serum IgE levels and serum eosinophils.

CONCLUSIONS

Our analyses suggest that FE_NO levels do not help discriminate between those with and without AO in patients with PD-asthma. Patients who experience symptoms of asthma may have elevated FE_NO levels above the suggested cut points of 20-25 ppb. Objective confirmation of AO should be considered in all patients with PD-asthma, irrespective of FE_NO levels.

Health status and lung function in the Swedish alpha 1-antitrypsin deficient cohort, identified by neonatal screening, at the age of 37-40 years

BACKGROUND

Severe alpha 1-antitrypsin (AAT) deficiency (genotype PiZZ) is a well-known risk factor for COPD. A cohort of PiZZ and PiSZ individuals was identified by the Swedish national neonatal AAT screening program in 1972-1974 and followed up regularly since birth. Our aim was to study the lung function, respiratory symptoms and health status at the age of 38 years in comparison with a random sample of control subjects selected from the population registry.

METHODS

The study group included 120 PiZZ, 46 PiSZ and 164 control subjects (PiMM), who answered a questionnaire on smoking habits and symptoms and the Saint George Respiratory Questionnaire (SGRQ) on quality of life. A total of 89 PiZZ, 33 PiSZ and 92 PiMM subjects underwent spirometry.

RESULTS

Four percent of the PiZZ, 2% of the PiSZ and 12% of the control subjects were current smokers (P=0.008), and 17% of the PiZZ, 9% of the PiSZ and 21% of the control subjects had stopped smoking. The PiZZ current smokers had a significantly higher (ie, poorer) median activity score according to the SGRQ than the PiZZ never-smokers (P=0.032). The PiMM current smokers had significantly higher activity score (P<0.001), symptom score (P<0.001), and total score (P=0.001) according to the SGRQ than the PiMM never-smokers. The PiZZ current smokers had a significantly lower postbronchodilator forced expiratory volume in 1 second (FEV1)% of predicted value (P=0.019) and FEV1/forced vital capacity (FVC) ratio (P=0.032) than the PiZZ never-smokers. The proportion of subjects with a FEV1/FVC ratio of <0.70, indicating COPD, was significantly higher in the PiZZ current smokers than in the PiZZ never-smokers (P=0.001). Among the PiSZ and PiMM subjects, the differences in lung function between the smoking subgroups were insignificant.

CONCLUSION

PiZZ current smokers were found to have signs of COPD before 40 years of age. Smoking is less common among the AAT-deficient subjects identified by neonatal screening than among their peers in the general population.

Addressing the misdiagnosis of asthma in adults: where does it go wrong?

INTRODUCTION

Asthma is diagnosed based on patients' respiratory symptoms of wheeze, cough, chest tightness and/or dyspnea together with physiologic evidence of variable and reversible expiratory airflow limitation. A high prevalence of overdiagnosis, underdiagnosis and misdiagnosis of adult asthma has been reported in the literature. Areas covered: Misdiagnosis of asthma in adults can occur in the community due to physicians' failure to confirm airflow limitation using spirometry, the relatively poor sensitivity of spirometry to absolutely rule in asthma, the complexity of multiple asthma phenotypes and endotypes, and the inherent day to day variability of asthma symptoms and airflow limitation. Consequences of asthma misdiagnosis to the patient and to the healthcare system include increased medication costs, increased potential side effects related to unnecessary use of medications and lost opportunities to diagnose the true cause of patients' respiratory symptoms. Expert commentary: Here we provide a review of the problem of misdiagnosis of adult asthma and suggestions for how to decrease the risk of misdiagnosis.

Diagnostic significance of nitric oxide concentrations in exhaled air from the airways in allergic rhinitis patients

INTRODUCTION

The effect of nitric oxide (NO) on the human body is very important due its physiological regulation of the following functions of airways: modulation of ciliary movement and maintenance of sterility in sinuses.

AIM

To evaluate the diagnostic significance of NO concentrations in exhaled air from the upper and lower airways in patients diagnosed with allergic rhinitis (AR).

MATERIAL AND METHODS

The subjects included in the study were a group of 30 people diagnosed with sensitivity to environmental allergens and a control group consisting of 30 healthy subjects. The measurement of NO in the air exhaled from the lower and upper airways was performed using an on-line method by means of Restricted Exhaled Breath (REB), as well as using the measurement procedure (chemiluminescence) set out in the guidelines prepared in 2005 by the American Thoracic Society and the European Respiratory Society.

RESULTS

In the late phase of the allergic reaction, higher values of the level of exhaled NO concentration from the lower airways were observed in the groups of subjects up to the threshold values of 25.17 ppb in the group of subjects with year-round allergic rhinitis and 21.78 ppb in the group with diagnosed seasonal allergic rhinitis. The difference in the concentration of NO exhaled from the lungs between the test group and the control group in the 4(th) h of the test was statistically significant (p = 0.045).

CONCLUSIONS

Exhaled NO should be considered as a marker of airway inflammation. It plays an important role in the differential diagnosis of allergy.

Correlation of nasal nitric oxide measurement with computed tomography findings in chronic rhinosinusitis

Nitric oxide (NO) is a biological messenger produced by mammalian cells serving various functions including regulation of blood flow, platelet function, immunity, and neurotransmission. The paranasal sinuses and nasal mucosa are a major source of exhaled NO. The aim of the study is to compare the nasal NO (nNO) levels in patients with chronic rhinosinusitis with those of common cold patients and controls and to correlate CT scores with nNO levels. The nasal concentration of NO was measured by electroluminescence in 13 healthy volunteers, in 13 patients suffering from common cold and 13 patients with chronic rhinosinusitis. The concentration of NO was correlated with symptom scores, endoscopic findings and CT findings. The measured levels of NO did not differ between healthy volunteers and common cold patients, but they were significantly lower in patients suffering from chronic rhinosinusitis. As NO is a regulator of mucociliary activity and has bacteriostatic and antiviral effects, the decreased concentration of nNO in patients suffering from sinusitis suggests that lack of NO may contribute to the pathogenesis of this disease. Thus, nNO, which is easily measured, provides a valuable non-invasive objective measure of chronic rhinosinusitis.

A phase 1, randomized, placebo-controlled, dose-escalation study of an anti-IL-13 monoclonal antibody in healthy subjects and mild asthmatics

AIMS

IL-13 is implicated as an important mediator of the pathology of asthma. This first clinical study with GSK679586, a novel humanized anti-IL-13 IgG1 monoclonal antibody, evaluated the safety, pharmacokinetics and pharmacodynamics of escalating single and repeat doses of GSK679586.

METHODS

In this randomized, double-blind study, healthy subjects received single intravenous infusions of GSK679586 (0.005, 0.05, 0.5, 2.5, 10 mg kg(-1)) or placebo and mild intermittent asthmatics received two once monthly intravenous infusions of GSK679586 (2.5, 10, 20 mg kg(-1)) or placebo.

RESULTS

GSK679586 displayed approximately linear pharmacokinetics (based on AUC and C(max)) with limited accumulation upon repeat administration. In mild intermittent asthmatics, treatment with GSK679586 produced an increase in serum total IL-13 concentrations, indicative of GSK679586-IL-13 complex formation. Additionally, mean levels of exhaled nitric oxide (FeNO), a marker of pulmonary inflammation, were reduced relative to baseline at 2.5, 10 and 20 mg kg(-1) doses of GSK679586 at both 2 weeks (19%, 44% and 52% decreases) and 8 weeks (29%, 55% and 42% decreases) after the second infusion. GSK679586 was well tolerated; the incidence of AEs was comparable across all presumed biologically active doses and there were no treatment-related SAEs.

CONCLUSIONS

GSK679586 demonstrated dose-dependent pharmacological activity in the lungs of mild intermittent asthmatics. These findings, together with the favourable safety profile and advantageous PK characteristics of a monoclonal antibody (e.g. a long half-life supporting less frequent dosing), warrant further investigation of GSK679586 in a broader asthma patient population.

Early respiratory and ocular involvement in X-linked hypohidrotic ectodermal dysplasia

X-linked hypohidrotic ectodermal dysplasia (XLHED; ectodysplasin deficiency) has been classically described as affecting hair, sweat glands, and dentition. What may be underappreciated is the effect ectodysplasin deficiency has on glands surrounding the airways and eyes and the resulting chronic health issues. In this study, 12 male children (age range 6-13 years) and 14 male adults with XLHED (18-58 years of age) were investigated by pulmonary function tests, measurement of fractional exhaled nitric oxide, and by ophthalmologic assessments. Twelve healthy individuals (six children, six adults) served as controls. Signs of airway constriction and inflammation were detected in eight children with XLHED, including the youngest subject, and in ten adult XLHED patients. Increased tear osmolarity, reduced tear film break-up time, and other ocular abnormalities were also present at an early age. Five of 12 XLHED subjects not reporting a history of asthma and 7 of the 12 patients not reporting a history of dry eye issues showed at least two abnormal test results in the respective organ system. The presence of residual sweat ducts, suggestive of partial ectodysplasin gene expression, correlated with milder disease in two XLHED subjects with mutations affecting the collagen-like domain of ectodysplasin.

CONCLUSION

The high prevalence of asthma-like symptoms in XLHED patients as young as 6 years and a similar prevalence of dry eye problems indicate that screening evaluation, regular monitoring, and consideration of therapeutic intervention should begin in early childhood.

Breath isoprene concentrations in persons undergoing general anesthesia and in healthy volunteers

Human breath contains an abundance of volatile organic compounds (VOCs). Analysis of breath VOC may be used for diagnosis of various diseases or for on-line monitoring in anesthesia and intensive care. However, VOC concentrations largely depend on the breath sampling method and have a large inter-individual variability. For the development of breath tests, the influence of breath sampling methods and study subject characteristics on VOC concentrations has to be known. Therefore, we investigated the VOC isoprene in 62 study subjects during anesthesia and 16 spontaneously breathing healthy volunteers to determine (a) the influence of artificial and spontaneous ventilation and (b) the influence of study subject characteristics on breath isoprene concentrations. We used ion molecule reaction mass spectrometry for high-resolution breath-by-breath analysis of isoprene. We found that persons during anesthesia had significantly increased inspiratory and end-expiratory isoprene breath concentrations. Measured isoprene concentrations (median [first quartile-third quartile]) were in the anesthesia group: 54 [40-79] ppb (inspiratory) and 224 [171-309] ppb (end-expiratory), volunteer group: 14 [11-17] ppb (inspiratory) and 174 [124-202] ppb (end-expiratory). Higher end-tidal CO(2) concentrations in ventilated subjects were associated with higher expiratory isoprene levels. Furthermore, inspiratory and end-expiratory isoprene concentrations were correlated during anesthesia (r = 0.603, p < 0.001). Multivariate analysis showed that men had significantly higher end-expiratory isoprene concentrations than women. Rebreathing of isoprene from the anesthesia machine possibly accounts for the observed increase in isoprene in the anesthesia group.

Effect of urbanisation on asthma, allergy and airways inflammation in a developing country setting

BACKGROUND

Asthma is a growing public health problem in developing countries. However, few studies have studied the role of urbanisation in this phenomenon. It was hypothesised that children living in a peri-urban setting in Peru have higher rates of asthma and allergy than rural counterparts.

METHODS

1441 adolescents aged 13-15 years were enrolled from two settings: a peri-urban shanty town in Lima (n = 725) and 23 rural villages in Tumbes (n = 716). Participants filled in questionnaires on asthma and allergy symptoms, environmental exposures and sociodemographics, and underwent spirometry, and exhaled nitric oxide (eNO) and allergy skin testing. Indoor particulate matter (PM) concentrations were measured in 170 households.

RESULTS

Lima adolescents had higher rates of lifetime wheezing (22% vs 10%), current asthma symptoms (12% vs 3%) and physician-diagnosed asthma (13% vs 2%; all p <0.001). Current rhinitis (23% vs 12%), eczema (12% vs 0.4%), atopy (56% vs 38%), personal history of cigarette smoking (7.4% vs 1.3%) and mean indoor PM (31 vs 13 μg/m(3)) were also higher in Lima (all p < 0.001). The peri-urban environment of Lima was associated with a 2.6-fold greater odds (95% CI 1.3 to 5.3) of asthma in multivariable regression. Forced expiratory volumes were higher and FEV(1)/FVC (forced expiratory volume in 1 s/forced vital capacity) ratios were lower in Lima (all p < 0.001). Higher eNO values in Lima (p < 0.001) were attributable to higher rates of asthma and atopy.

CONCLUSIONS

Peri-urban adolescents had more asthma, atopy and airways inflammation and were exposed to more indoor pollution. The findings provide evidence of the risks posed to lung health by peri-urban environments in developing countries.

Adiposity, adipokines, and exhaled nitric oxide in healthy adults without asthma

BACKGROUND

Epidemiological studies have shown that obesity/adiposity is closely associated with asthma in terms of development, severity, and control of asthma. However, effects of obesity/adiposity on airway inflammation are not well known in subjects without asthma. We assessed whether fractional exhaled nitric oxide (FeNO), a marker of eosinophilic airway inflammation, was associated with obesity/adiposity in nonasthmatic healthy adults.

METHODS

We measured FeNO and serum levels of adipose-derived hormones and adipokines in 117 adult subjects without a previous diagnosis of asthma or current asthmatic symptoms. Associations between FeNO and measures of obesity/adiposity [body mass index (BMI), body fat mass, and body fat percentages] were examined by correlation analyses and uni- and multivariate linear regression analyses.

RESULTS

FeNO was not significantly associated with BMI, body fat mass, or body fat percentage by a multivariate linear regression model, adjusting for age, gender, chronic rhinitis, atopy, and lung function. No significant association of FeNO with serum levels of leptin, adiponectin, tumor necrosis factor (TNF)-α, or interleukin (IL)-6 was observed.

CONCLUSIONS

These findings suggest that in healthy subjects without asthma, obesity/adiposity has no significant effect on eosinophilic airway inflammation and that hormones and systemic inflammation derived from adipose tissue do not affect eosinophilic airway inflammation.

Monitoring asthma control in children with allergies by soft computing of lung function and exhaled nitric oxide

BACKGROUND

Asthma control is emphasized by new guidelines but remains poor in many children. Evaluation of control relies on subjective patient recall and may be overestimated by health-care professionals. This study assessed the value of spirometry and fractional exhaled nitric oxide (FeNO) measurements, used alone or in combination, in models developed by a machine learning approach in the objective classification of asthma control according to Global Initiative for Asthma guidelines and tested the model in a second group of children with asthma.

METHODS

Fifty-three children with persistent atopic asthma underwent two to six evaluations of asthma control, including spirometry and FeNO. Soft computing evaluation was performed by means of artificial neural networks and principal component analysis. The model was then tested in a cross-sectional study in an additional 77 children with allergic asthma.

RESULTS

The machine learning method was not able to distinguish different levels of control using either spirometry or FeNO values alone. However, their use in combination modeled by soft computing was able to discriminate levels of asthma control. In particular, the model is able to recognize all children with uncontrolled asthma and correctly identify 99.0% of children with totally controlled asthma. In the cross-sectional study, the model prospectively identified correctly all the uncontrolled children and 79.6% of the controlled children.

CONCLUSIONS

Soft computing analysis of spirometry and FeNO allows objective categorization of asthma control status.

Exhaled breath condensate and airway inflammation

PURPOSE OF REVIEW

The collection of exhaled breath condensate (EBC) is a noninvasive method for evaluation of airway inflammation. This article reviews recent data concerning the ability of EBC markers to reflect alterations in asthma and chronic obstructive pulmonary disease or environment and occupation-induced changes.

RECENT FINDINGS

The recovery of biomarkers in EBC is affected by physical characteristics of the condensing device and collecting circumstances as well as environmental conditions or exercise. The complexities of nitrogen oxide chemistry make assessment of nitric oxide metabolites in EBC and exhaled nitric oxide complementary. Analysing of EBC markers is valuable in asthma, as changes were reported irrespective of current anti-inflammatory treatment or atopic status as well as in monitoring cigarette smoking-related airway inflammation in chronic obstructive pulmonary disease patients. Hyperinflation in chronic obstructive pulmonary disease might be a potential confounder for the level of inflammation markers in EBC. In general, patterns of markers are likely to more accurately reflect the complex pathophysiological processes and therefore should be evaluated rather than a single marker.

SUMMARY

EBC might be of particular interest in preventive medicine as inflammatory processes triggered may precede changes in lung function. Robust and easy-to-handle condensing devices and analytical methods are warranted to spread the use of EBC.

Novel biomarkers in asthma: chemokines and chitinase-like proteins

PURPOSE OF REVIEW

Allergic asthma is a frequent lung disease in Western civilizations and is characterized by airway inflammation and tissue remodeling. Without early diagnosis and specific treatment, asthma results in a loss of lung function, impaired quality of life and the risk to die from uncontrolled asthma attacks. Thus, there is a need for specific biomarkers to detect asthma as soon as possible and to initiate the correct clinical treatment.

RECENT FINDINGS

Recent studies have highlighted the potential role of the chemokine (C-C motif) ligand 17 and the chitinase-like protein YKL-40 as novel biomarkers in asthma. Patient studies suggest that these proteins could be useful to identify asthmatics, to characterize disease severity or both in patients with asthma. Functional studies indicate that these molecules are more than correlated epiphenomena and instead contribute in significant ways to asthma pathogenesis.

SUMMARY

Assessments of chemokine (C-C motif) ligand 17 and YKL-40 may allow physicians to more accurately diagnose and predict the course of asthma and thereby allow therapy to be appropriately tailored for a given patient.

Physical characteristics and aerosol performance of naringin dry powders for pulmonary delivery prepared by spray-drying

The aim of the present work was to develop dry powders containing naringin for a direct administration to the lung to combat oxidative stress. Naringin microparticles were prepared by spray-drying the neat flavonoid (2-5% w/v) from different water/ethanol co-solvents. The spray-dried powders were characterised for morphology, density, particle size distribution, residual humidity, crystallinity, solubility, thermal behaviour and respirable fraction. The fine fraction of the powders was measured by single-stage glass impinger and Andersen cascade impactor, using the Turbospin device for the deposition tests, wherein the dose to be aerosolised was premetered in a gelatine capsule. By increasing the ethanol content, the feed liquid turned from a suspension into a solution: the spray of flavonoid suspensions led to powders with high crystallinity degree, low water solubility and high bulk density, while the spray of drug solutions led to more amorphous particles, with higher solubility, lower density and improved aerodynamic behaviour. The optimisation of the operative parameters produced enhanced aerosol performance of the flavonoid powders containing only the active compound.