Exhaled nitric oxide, systemic inflammation, and the spirometric response to inhaled fluticasone propionate in severe chronic obstructive pulmonary disease: a prospective study

Clinical utilization of airway inflammatory biomarkers in the prediction and monitoring of clinical outcomes in patients with chronic obstructive pulmonary disease

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) accounts for 545 million people living with chronic respiratory disorders and is the third leading cause of morbidity and mortality around the world. COPD is a progressive disease, characterized by episodes of acute worsening of symptoms such as cough, dyspnea, and sputum production.

AREAS COVERED

Airway inflammation is a prominent feature of COPD. Chronic airway inflammation results in airway structural remodeling and emphysema. Persistent airway inflammation is a treatable trait of COPD and plays a significant role in disease development and progression. In this review, the authors summarize the current and emerging biomarkers that reveal the heterogeneity of airway inflammation subtypes, clinical outcomes, and therapeutic response in COPD.

EXPERT OPINION

Airway inflammation can be broadly categorized as eosinophilic (type 2 inflammation) and non-eosinophilic (non-type 2 inflammation) in COPD. Currently, blood eosinophil counts are incorporated in clinical practice guidelines to identify COPD patients who are at a higher risk of exacerbations and lung function decline, and who are likely to respond to inhaled corticosteroids. As new therapeutics are being developed for the chronic management of COPD, it is essential to identify biomarkers that will predict treatment response.

Fractional nitric oxide measurement in exhaled air (FeNO): perspectives in the management of respiratory diseases

Exhaled nitric oxide (NO) production, upregulated by inflammatory cytokines and mediators in central and peripheral airways, can be easily and non-invasively detected in exhaled air in asthma and other respiratory conditions as a promising tool for disease monitoring. The American Thoracic Society and European Respiratory Society released recommendations that standardize the measurement of the fractional exhaled NO (FeNO). In asthma, increased FeNO reflects eosinophilic-mediated inflammatory pathways and, as a biomarker of T2 inflammation can be used to identify asthma T2 phenotype. In this setting its measurement has shown to be an important tool especially in the diagnostic process, in the assessment and evaluation of poor adherence or predicting positive response to inhaled corticosteroids treatment, in phenotyping severe asthma patients and as a biomarker to predict the response to biologic treatments. The discovery of the role of NO in the pathogenesis of different diseases affecting the airways and the possibility to estimate the predominant site of increased NO production has provided new insight on its regulatory role in the airways, making it suitable for a potential extended use in clinical practice for different pulmonary diseases, even though its role remains less clear than in asthma. Monitoring FeNO in pulmonary obstructive lung diseases including chronic bronchitis and emphysema, interstitial lung diseases, obstructive sleep apnea and other pulmonary diseases is still under debate but has opened up a window to the role NO may play in the management of these diseases. The use of FeNO is reliable, cost effective and recommendable in both adults and children, and should be implemented in the management of patients with asthma and other respiratory conditions.

Cleaning up alpha-1 antitrypsin deficiency related liver disease

PURPOSE OF REVIEW

Alpha-1 antitrypsin deficiency (AATD) is one of the most common genetic disorders arising due to mutations in alpha-1 antitrypsin (AAT) gene affecting primarily the lung and the liver. This review summarizes the pathophysiology and clinical manifestation of different AATD genotypes and discusses the recent therapeutic developments. The focus is on the severe, rare homozygous Pi∗ZZ and the common heterozygous Pi∗MZ genotype.

RECENT FINDINGS

Pi∗ZZ individuals harbor an up to 20 times higher risk of liver fibrosis and cirrhosis than noncarriers and liver transplantation is currently the only available therapeutic option. AATD constitutes a proteotoxic disorder arising from hepatic AAT accumulation and the currently most promising data come from a phase 2, open-label trial of fazirsiran, a hepatocyte-targeted siRNA. Pi∗MZ subjects display an increased risk of advanced liver disease and at the latter stage, a faster deterioration than individuals without AAT mutation.

SUMMARY

Although the fazirsiran data offer a glimpse of hope to AATD patients, a consensus on appropriate study endpoint, a careful patient selection as well as monitoring of long-term safety will be essential for an approval.

Fractional Exhaled Nitric Oxide Guided-Therapy in Chronic Obstructive Pulmonary Disease: A Stratified, Randomized, Controlled Trial

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) with eosinophilic airway inflammation represents a distinct phenotype that might respond to treatment with inhaled corticosteroids. Fractional exhaled nitric oxide (FENO) might predict eosinophilic inflammation and guide treatment option. We hypothesized that COPD patients with different baseline levels of FENO might have differentiated response to treatment with salmeterol/fluticasone (SFC) or tiotropium (TIO).

METHODS

This open-label, randomized-controlled trial enrolled treatment-naïve COPD patients who were stratified into high- (≥23.5ppb) and low-FENO group, followed by 12-week treatment with SFC or TIO. A linear mixed model with repeated measures was applied to analyze the changes in FENO (primary outcome), COPD assessment test (CAT) score, FEV₁, and parameters in induced sputum and blood after treatment.

RESULTS

134 patients were divided into 4 subgroups: low-FENO/SFC (n=30), low-FENO/TIO (n=29), high-FENO/SFC (n=37), and high-FENO/TIO (n=38). At baseline, FENO 23.5ppb clearly differentiated between eosinophilic and non-eosinophilic inflammation groups based on the eosinophils in induced sputum and blood. FENO significantly correlated with sputum and blood eosinophils at baseline. High-FENO/SFC (vs. high-FENO/TIO) subgroup had significant reduction in FENO and sputum inflammation profiles (including eosinophils, macrophages, matrix metalloproteinase-9, and interlukin-8) after treatment. These differences were not replicated between low-FENO/SFC and low-FENO/TIO subgroups. The improvement in CAT and FEV₁ after treatment was indiscriminate between SFC and TIO in the low- and high-FENO groups.

CONCLUSION

High baseline FENO can serve as an indicator of eosinophilic airway inflammation in COPD patients who may respond favorably to treatment with inhaled corticosteroids/long-acting β₂-agonists.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Identifier: NCT02546349.

Role of oxidative stress in the pathogenesis of COPD

Chronic inhalation of cigarette smoke is a prominent cause of chronic obstructive pulmonary disease (COPD) and provides an important source of exogenous oxidants. In addition, several inflammatory and structural cells are a source of endogenous oxidants in the lower airways of COPD patients, even in former smokers. This suggests that oxidants play a key role in the pathogenesis of COPD. This oxidative stress is counterbalanced by the protective effects of the various endogenous antioxidant defenses of the lower airways. A large amount of data from animal models and patients with COPD have shown that both the stable phase of the disease, and during exacerbations, have increased oxidative stress in the lower airways compared with age-matched smokers with normal lung function. Thus, counteracting the increased oxidative stress may produce clinical benefits in COPD patients. Smoking cessation is currently the most effective treatment of COPD patients and reduces oxidative stress in the lower airways. In addition, many drugs used to treat COPD have some antioxidant effects, however, it is still unclear if their clinical efficacy is related to pharmacological modulation of the oxidant/antioxidant balance. Several new antioxidant compounds are in development for the treatment of COPD.

Diagnostic value of fractional exhaled nitric oxide in differentiating the asthma-COPD overlap from COPD: a systematic review and meta-analysis

BACKGROUND

Patients with asthma-COPD overlap (ACO) account for 15-20% of chronic obstructive pulmonary disease (COPD), and the incidence increases with age. Patients with ACO have worse outcomes without proper treatment than those with COPD alone. However, the current diagnostic criteria of ACO are mainly based on symptom features and lack of objective indicators. Recently, several studies have demonstrated that fractional exhaled nitric oxide (FeNO) was higher in ACO than in COPD alone. Thus, this study aims to determine the diagnostic value of FeNO in differentiating ACO from COPD and assisting clinical decision-making.

METHODS

We conducted searches in the databases including PubMed, Web of Science, Cochrane Library, and Embase to extract original studies.

RESULTS

In all, 10 studies involving 1335 participants were included in this meta-analysis. FeNO level was significantly higher in ACO patients than in patients with COPD alone (WMD = 11.15ppb, 95%CI = 9.01‒13.28; I² = 18.0%, p = 0.000). The sensitivity and specificity of FeNO in distinguishing ACO from COPD were both 0.71, and the area under the receiver-operating characteristic curve (AUC) was 0.76, indicating that FeNO has moderate diagnostic accuracy in differentiating ACO from COPD.

CONCLUSION

FeNO as an inflammatory biomarker is effective in differentiating ACO from COPD and assisting in clinical decision-making.

ACO (Asthma-COPD Overlap) Is Independent from COPD, a Case in Favor: A Systematic Review

Asthma and chronic obstructive pulmonary disease (COPD) are now recognized to be able to co-exist as asthma-COPD overlap (ACO). It is clinically relevant to evaluate whether patients with COPD concurrently have components of asthma in primary care. This is because: (i) ACO is a relatively common condition among asthma (over 40 years of age) or COPD irrespective of its diagnosis criteria; (ii) patients with ACO can have higher frequency of exacerbation and more rapid decline in lung function than those with asthma or COPD; and (iii) asthmatic features such as eosinophilic airway inflammation are promising indicators for prediction of inhaled corticosteroid-responsiveness in COPD. The aim of this review to evaluate diagnostic markers for ACO. We searched PubMed for articles related to ACO published until 2020. Articles associated with diagnostic biomarkers were included. We identified a total of 25 studies, some of which have revealed that a combination of biomarkers such as fractional exhaled nitric oxide and serum immunoglobulin E is useful to discern type 2 inflammation in the airways of COPD. Here, we review the current understanding of the clinical characteristics, biomarkers and molecular pathophysiology of ACO in the context of how ACO can be differentiated from COPD.

Role of Type2 Inflammatory Biomarkers in Chronic Obstructive Pulmonary Disease

Airway inflammation in chronic obstructive pulmonary disease (COPD) is typically thought to be driven by Type1 immune responses, while Type2 inflammation appears to be present in definite proportions in the stable state and during exacerbations. In fact, some COPD patients showed gene expression of Type2 inflammation in the airway, and this subset was associated with the inhaled corticosteroid (ICS) response. Interestingly enough, the relationship between COPD and diseases associated with Type2 inflammation from the perspective of impaired lung development is increasingly highlighted by recent epidemiologic studies on the origin of COPD. Therefore, many researchers have shown an interest in the prevalence and the role of existent Type2 biomarkers such as sputum and blood eosinophils, exhaled nitric oxide fraction, and atopy, not only in asthma but also in COPD. Although the evidence about Type2 biomarkers in COPD is inconsistent and less robust, Type2 biomarkers have shown some potential when analyzing various clinical outcomes or therapeutic response to ICS. In this article, we review the existent and emerging Type2 biomarkers with clinically higher applicability in the management of COPD.

Role of the Bronchodilator Test Defined by the Forced Vital Capacity in Chronic Obstructive Pulmonary Disease Phenotyping

Purpose

In clinical practice, some chronic obstructive pulmonary disease (COPD) patients experienced a remarkable increase in forced vital capacity (FVC) after bronchodilator administration, whereas forced expiratory volume in the first second (FEV1) remains substantially unchanged. We assume this may relate to airway inflammatory type. We aim to analyze the clinical characteristics and explore the usefulness of the bronchodilator test, especially FVC, in this new COPD phenotype.

Patients and Methods

A total of 346 COPD patients with exacerbation who underwent bronchodilator tests, fractional exhaled nitric oxide (FeNO) measurements and blood eosinophil counts were analyzed. The characteristics, FeNO levels, and blood eosinophil counts were compared between patients with and without significant bronchodilator responsiveness in terms of FVC.

Results

Patients with significant FVC responsiveness displayed poorer lung function and higher FeNO levels compared with those without considerable FVC responsiveness (Z= −5.042 to −0.375, p=0.000–0.022). There is a discernible linear relationship between FeNO levels and FVC responsiveness to bronchodilator use (r=0.251, P=0.001). The application of bronchodilator responsiveness of FVC for detecting high FeNO levels in COPD patients exhibited relatively high sensitivity (61.8%) and specificity (86.7%).

Conclusion

We demonstrated that COPD patients with significant FVC responsiveness had higher FeNO levels than non-responders and established a simple method for detecting high FeNO values. FVC responders may be identified as a separate group of COPD patients.

Associations between inhaled doses of PM2.5-bound polycyclic aromatic hydrocarbons and fractional exhaled nitric oxide

Exposure to fine particulate matter (PM_2.5) is linked to various respiratory outcomes. However, the associations of concentrations of PM_2.5-bound polycyclic aromatic hydrocarbons (PM_2.5-bound PAHs) with airway inflammatory indices remains unclear. To assess effects of short-term exposure to PM_2.5-bound PAHs on fractional exhaled nitric oxide (FeNO), we conducted a pilot study with repeated measures. We recruited 20 postgraduate students in Wuhan city, China, and repeatedly measured outdoor and indoor (including dormitories, offices and laboratories) PM_2.5-bound PAHs concentrations, urinary monohydroxy polycyclic aromatic hydrocarbons (OH-PAHs) and FeNO levels in the four seasons. Subsequently, we estimated inhaled doses of PM_2.5-bound PAHs based on the micro-environmental PM_2.5-bound PAHs concentrations, time-activity patterns and referred inhalation rates. We assessed the association of inhaled doses of PM_2.5-bound PAHs with FeNO using linear mixed-effects regression models. We found the positive associations of urinary ∑OH-PAHs levels with inhaled doses of indoor PM_2.5-bound PAHs (including dormitories and offices) (all p < 0.05). A one-unit increase in inhaled doses of PM_2.5-bound PAHs or in urinary concentrations of ∑OH-PAHs was corresponded to a maximum FeNO increase of 13.5% (95% CI: 5.4, 22.2) at lag2 day or of 6.8% (95% CI: 3.4, 10.2) at lag1 day. Inhaled doses of PM_2.5-bound PAHs or urinary OH-PAHs was positively related to increased FeNO, they may be accepted as a short-term biomarker of exposure to PAHs in air. Exposure to PM_2.5-bound PAHs in indoor air may contribute more to the body burden of PAHs than outdoor air, and exhibited stronger effect on increased FeNO rather than urinary OH-PAHs.

Treatment of chronic obstructive pulmonary disease in patients with different fractional exhaled nitric oxide levels

Some patients with chronic obstructive pulmonary disease (COPD) have eosinophilic inflammation which may be evaluated via the measurement of fractional exhaled nitric oxide (FeNO) like asthma. The aim of this prospective study was to assess whether FeNO levels can be used to identify patients with COPD with eosinophilic inflammation who may respond to inhaled corticosteroid (ICS) therapy.This study included patients (N = 112) with COPD (age >18 years) who were divided into 4 groups depending upon whether they had high (≥25 parts per billion [ppb]) or low (<25 ppb) pretreatment (baseline) FeNO and if they were treated with either ICS plus long-acting β-agonist (ICS + LABA) or a long-acting muscarinic antagonist (LAMA). The 4 groups were: high FeNO/ICS + LABA, high FeNO/LAMA, low FeNO/ICS + LABA, and low FeNO/LAMA. Outcomes assessed included FeNO, COPD assessment test (CAT), and pulmonary function.The high FeNO/ICS + LABA group had the greatest reduction from baseline in FeNO levels (-25.80 ppb ± 27.14) compared with the high FeNO/LAMA, low FeNO/ICS + LABA, and low FeNO/LAMA groups (range, -4.45 to 1.31 ppb; P < .001). The high FeNO/ICS + LABA group also showed the greatest improvement in CAT (-7.20), which was statistically larger than the low FeNO/ICS + LABA and low FeNO/LAMA groups (-1.72 and -2.03, respectively). No difference in pulmonary function following treatment was observed across the 4 groups.This study found that patients with high FeNO showed the greatest reduction in FeNO and improvement in CAT with ICS + LABA therapy, supporting the use of FeNO to identify patients who would benefit from ICS use.

Investigating Fractional Exhaled Nitric Oxide in Chronic Obstructive Pulmonary Disease (COPD) and Asthma-COPD Overlap (ACO): A Scoping Review

Chronic obstructive pulmonary disease (COPD) is the most common fixed airflow limitation. Individuals may present with the features of both asthma and COPD called asthma-COPD overlap (ACO) with more severity and worse health-related quality of life than COPD or asthma. One of the promising biomarkers that could be used in clinical practice to differentiate ACO from COPD is fractional exhaled nitric oxide (F_ENO). The role of Fractional exhaled nitric oxide (F_ENO) in COPD/ACO remains unknown. This scoping review aims to investigate the role of F_ENO measurement to differentiate COPD from ACO, to anticipate disease severity/progression and treatment response. A structured comprehensive literature search was performed in major databases including Medline, EMBASE, CINAHL, Cochrane Library, Web of Science, and BIOSIS from 2005 onwards. Thirty-eight studies were retrieved. Based on the synthesis of the reviewed literature, six themes emerged. Thirty-four articles covered more than one theme. From which, 24 articles were on modifying factors in F_ENO measurement, 18 on F_ENO in COPD compared with healthy subjects, and seven on F_ENO in ACO compared with COPD, 22 on F_ENO and disease severity/progression,12 on F_ENO and biomarkers, and eight on F_ENO and treatment response. F_ENO measurement cannot be used alone in the clinical settings of COPD patients. Although F_ENO level is higher in ACO patients than COPD-only, it is still unclear if there is a F_ENO cut-off that can be used to make the diagnosis of ACO and/or to guide therapy with inhaled corticosteroids/glucocorticoids in COPD patients.

Late-onset asthma: current perspectives

Because the pathophysiology of asthma has diverse characteristics, to manage the disease effectively, it is important for clinicians to distinguish among the clinical phenotypes. Among them, adult-onset asthma, that is, late-onset asthma (LOA), is increasing because of the aging of the population. The phenotype of LOA is largely divided into two types according to the presence or absence of eosinophilic inflammation, T-helper (Th)2- and non-Th2-associated LOA. Especially in Th2 LOA related to rhinosinusitis, as pulmonary function at onset is poor and asthma exacerbations occur frequently, it is important to detect this phenotype in the early phase by using a biomarker of Th2-type inflammation such as fractional exhaled nitric oxide (FENO). As non-Th2-LOA is often resistant to corticosteroids, this phenotype often requires another treatment strategy such as macrolide, diet, or smoking cessation. We often struggle with the management of LOA patients due to a lack of evidence; therefore, the elucidation of the mechanism of LOA contributes to increased efficiency of diagnosis and treatment of LOA. Age-related immune system and structural changes are thought to be associated with the pathophysiology of LOA. In the former case, changes in inflammatory cell function such as variations in the innate immune response and acquisition of autoimmunity or upregulation of oxidative stress are thought to be involved in the mechanism. Meanwhile, the latter can also become triggers or exacerbating factors of LOA via enhancement of airway hyperresponsiveness, decline in lung function, increased air trapping, and reduction in chest wall compliance. Therefore, appropriate individualized management in LOA may be possible through precisely assessing the pathophysiology based on age-related functional changes, including the immune and structural system.

The recent advances of phenotypes in acute exacerbations of COPD

Exacerbations of COPD are clinically relevant events with therapeutic and prognostic implications. Yet, significant heterogeneity of clinical presentation and disease progression exists within acute exacerbations of COPD (AECOPD). Currently, different phenotypes have been widely used to describe the characteristics among patients with AECOPD. This has proved to be significant in the treatment and prediction of the outcomes of the disease. In this review of published literature, the phenotypes of AECOPD were classified according to etiology, inflammatory biomarkers, clinical manifestation, comorbidity, the frequency of exacerbations, and so on. This review concentrates on advancements in the use of phenotypes of AECOPD.

The use of cellular and molecular biomarkers to manage COPD exacerbations

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) exacerbations are a common cause of respiratory morbidity and mortality, and have various etiologies. Multiple cellular and molecular biomarkers have been associated with exacerbations. Quantitative sputum cell counts are able to identify the presence and type of bronchitis, which is an important contributor to exacerbations. Their utility to monitor bronchitis and to help treat exacerbations has been evaluated, yet they are not used in routine clinical practice. Areas covered: This review will provide a brief summary of biomarkers utilized in COPD, with a focus on the application of cellular markers for the management of exacerbations. A case study will demonstrate the application of these methods. With quantitative sputum cell counts, the presence of eosinophilic bronchitis predicts corticosteroid-responsiveness, while neutrophilic bronchitis identifies infection and suggests the need for antibiotics. Gastroesophageal reflux-related aspiration and heart failure can also be identified by examining sputum. Expert commentary: Quantitative sputum cytometry is an essential tool in the management of exacerbations of COPD, particularly those prone to frequent exacerbations. Treatment based on sputum cell counts is superior to current guideline-based recommendations to prevent future exacerbations and hospitalizations in observational and single-centre controlled trials. Large multicentre clinical trials are necessary to confirm this.

Utilising exhaled nitric oxide information to enhance diagnosis and therapy of respiratory disease - current evidence for clinical practice and proposals to improve the methodology

INTRODUCTION

A non-invasive tool to diagnose respiratory diseases and to follow treatment has long been looked-for. Exhaled nitric oxide (NO) is a promising marker of inflammation in asthma but nearly 25-years of research has shown that it works in only certain endotypes of asthma. The modelling of NO dynamics of the lung can give more information than a single F_ENO value. Areas covered: The estimation of the NO production in the conducting airways and in the gas exchange area has given new insight of the NO production in diseases beyond asthma. In this article, we discuss the importance of methodology for NO measurement in the exhaled breath and the indication of applying this technique to detect respiratory disorders. This narrative review is an attempt to examine and discuss the physiological basis underlying exhaled NO measurements and the clinical evidence of the usefulness of this method in asthma and various other respiratory disorders. Expert commentary: Estimation of the NO parameters would aid in our understanding of the NO dynamics of the lung and thereby give more knowledge how to interpret the measured F_ENO value in clinical practice.

Inhaled corticosteroids with combination inhaled long-acting beta2-agonists and long-acting muscarinic antagonists for chronic obstructive pulmonary disease

BACKGROUND

Management of chronic obstructive pulmonary disease (COPD) commonly involves long-acting bronchodilators including beta-agonists (LABA) and muscarinic antagonists (LAMA). In individuals with persistent symptoms or frequent exacerbations, inhaled corticosteroids (ICS) are also used. LABA and LAMA bronchodilators are now available in single combination inhalers. However, the benefits and risks of adding ICS to combination LABA/LAMA inhalers remains unclear.

OBJECTIVES

To assess the effect of adding an inhaled corticosteroid (ICS) to combination long-acting beta₂-agonist (LABA)/long-acting muscarinic antagonist (LAMA) inhalers for the treatment of stable COPD.

SEARCH METHODS

We carried out searches using the Cochrane Airways Group Specialised Register of Trials (searched 20 September 2016), Cochrane Central Register of Controlled Trials (CENTRAL; 2015, Issue 12) in the Cochrane Library (searched 15 December 2015) and MEDLINE (searched 15 December 2015). We also searched ClinicalTrials.gov, World Health Organisation (WHO) trials portal and pharmaceutical company clinical trials' databases up to 7 Janurary 2016.

SELECTION CRITERIA

We included parallel-group, randomised controlled trials (RCTs) of three weeks' duration or longer which compared treatment of stable COPD with ICS in addition to combination LABA/LAMA inhalers against combination LABA/LAMA inhalers alone.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We identified a total of 586 records in our search. Following removal of duplicates, 386 abstracts were assessed for inclusion. Six studies were identified as potentially relevant; however, all failed to meet the inclusion criteria on full-text assessment or after contacting the corresponding author to clarify study characteristics.

AUTHORS' CONCLUSIONS

There are currently no studies published assessing the effect of ICS in addition to combination LABA/LAMA inhalers for the treatment of stable COPD. As combination LABA/LAMA inhalers are now widely available, there is a need for well-designed RCTs to investigate whether ICS provides any added therapeutic benefit.

Response of exhaled nitric oxide to inhaled corticosteroids in patients with stable COPD: A systematic review and meta-analysis

INTRODUCTION

To our knowledge, no meta-analysis has investigated the response of FeNO levels to corticosteroid treatment in ex-smokers with chronic obstructive pulmonary disease (COPD).

OBJECTIVES

This meta-analysis assessed the potential role of fraction of exhaled nitric oxide (FeNO) as a biomarker for corticosteroid response in ex-smokers with stable COPD.

METHODS

Medline, Cochrane, EMBASE, Google Scholar databases were searched until November 5, 2014 using the following terms: corticosteroid, chronic obstructive pulmonary disease, COPD, nitric oxide, NO, exhaled nitric oxide. Only randomized controlled trials (RCT) or two-arm prospective studies were included. The primary outcome measure was FeNO before and after treatment with inhaled corticosteroids (ICS) in ex-smokers with COPD. Sensitivity analysis was also performed.

RESULTS

Five studies were included in the analysis with a total of 171 COPD patients. All five studies included 125 ex-smokers and two of these also included 46 current smokers. There was a significant decrease of FeNO in ex-smoking COPD patients following inhaled corticosteroid treatment (-7.51, 95% CI: -11.51 to -3.51; P =0.003); and in a population of subjects that included both smokers and ex-smokers (-1.99, 95% CI: -3.41 to -0.56; P =0.006).

CONCLUSION

Our findings indicate that FeNO levels significantly decreased with corticosteroid treatment in ex-smokers with COPD. Additional studies are required to evaluate whether concurrent smoking has significant effect on FeNO response to ICS.

Exacerbations of COPD

Exacerbations of chronic obstructive pulmonary disease (COPD) are defined as sustained worsening of a patient’s condition beyond normal day-to-day variations that is acute in onset, and that may also require a change in medication and/or hospitalization. Exacerbations have a significant and prolonged impact on health status and outcomes, and negative effects on pulmonary function. A significant proportion of exacerbations are unreported and therefore left untreated, leading to a poorer prognosis than those treated. COPD exacerbations are heterogeneous, and various phenotypes have been proposed which differ in biologic basis, prognosis, and response to therapy. Identification of biomarkers could enable phenotype-driven approaches for the management and prevention of exacerbations. For example, several biomarkers of inflammation can help to identify exacerbations most likely to respond to oral corticosteroids and antibiotics, and patients with a frequent exacerbator phenotype, for whom preventative treatment is appropriate. Reducing the frequency of exacerbations would have a beneficial impact on patient outcomes and prognosis. Preventative strategies include modification of risk factors, treatment of comorbid conditions, the use of bronchodilator therapy with long-acting β₂-agonists or long-acting muscarinic antagonists, and inhaled corticosteroids. A better understanding of the mechanisms underlying COPD exacerbations will help to optimize use of the currently available and new interventions for preventing and treating exacerbations.

Effect of Personal Exposure to PM2.5 on Respiratory Health in a Mexican Panel of Patients with COPD

Background: Air pollution is a problem, especially in developing countries. We examined the association between personal exposure to particulate matter with an aerodynamic diameter less than 2.5 µm (PM_2.5) on respiratory health in a group of adults with chronic obstructive pulmonary disease (COPD). Methods: All participants resided in Mexico City and during follow-up, personal exposure to PM_2.5, respiratory symptoms, medications, and daily activity were registered daily. Peak expiratory flow (PEF) was measured twice daily, from February through December, 2000, in 29 adults with moderate, severe, and very severe COPD. PEF changes were estimated for each 10 µg/m³ increment of PM_2.5, adjustment for severity of COPD, minimum temperature, and day of the sampling. Results: For a 10-µg/m³ increase in the daily average of a two-day personal exposure to PM_2.5, there was a significant 33% increase in cough (95% CI, range, 5‒69%), and 23% in phlegm (95% CI, range, 2‒54%), a reduction of the PEF average in the morning of −1.4 L/min. (95% CI , range, −2.8 to −0.04), and at night of −3.0 L/min (95% CI, range, −5.7 to −0.3), respectively. Conclusions: Exposure to PM_2.5 was associated with reductions in PEF and increased respiratory symptoms in adults with COPD. The PEF reduction was observed both at morning and at night.

Application of nitric oxide measurements in clinical conditions beyond asthma

Fractional exhaled nitric oxide (FeNO) is a convenient, non-invasive method for the assessment of active, mainly Th2-driven, airway inflammation, which is sensitive to treatment with standard anti-inflammatory therapy. Consequently, FeNO serves as a valued tool to aid diagnosis and monitoring in several asthma phenotypes. More recently, FeNO has been evaluated in several other respiratory, infectious, and/or immunological conditions. In this short review, we provide an overview of several clinical studies and discuss the status of potential applications of NO measurements in clinical conditions beyond asthma.

The asthma COPD overlap syndrome (ACOS)

Asthma and chronic obstructive pulmonary disease (COPD) have traditionally been viewed as distinct clinical entities. Recently, however, much attention has been focused on patients with overlapping features of both asthma and COPD: those with asthma COPD overlap syndrome (ACOS). Although no universal definition criteria exist, recent publications attempted to define patients with ACOS based on differences in clinical features, radiographic findings, and diagnostic tests. Patients with ACOS make up a large percentage of those with obstructive lung disease and have a higher overall health-care burden. Identifying patients with ACOS has significant therapeutic implications particularly with the need for early use of inhaled corticosteroids and the avoidance of use of long-acting bronchodilators alone in such patients. However, unlike asthma and COPD, no evidence-based guidelines for the management of ACOS currently exist. Future research is needed to improve our understanding of ACOS and to achieve the best management strategies.

"Correct use of inhaled corticosteroids in chronic obstructive pulmonary disease": a consensus document

INTRODUCTION

Indications for inhaled corticosteroids (IC) in combination with long-acting bronchodilators (LABD) are well defined in clinical practice guidelines. However, there are some doubts about their efficacy and safety. The aim of this document is to establish an expert consensus to clarify these issues.

METHOD

A coordinator group was formed, which systematically reviewed the scientific evidence with the aim of identifying areas of uncertainty about the efficacy of ICs, the adverse effects associated with their use and criteria for withdrawal. Their proposals were submitted to a panel of experts and the Delphi technique was used to test the level of consensus.

RESULTS

Twenty-five experts participated in the panel, and consensus was reached on the use of IC in the mixed chronic obstructive pulmonary disease (COPD)-asthma phenotype and in frequent exacerbators, and on not using IC in association with LABD for improving lung function in COPD. There was no general consensus on restricting the use of IC to prevent adverse effects. The panel did agree that IC withdrawal is feasible but should be undertaken gradually, and patients who have discontinued must be evaluated in the short term.

CONCLUSIONS

Consensus was reached regarding the indication of IC in mixed COPD-asthma and frequent exacerbator phenotypes. The potential for adverse effects must be taken into consideration, but there is no consensus on whether limiting use is justified. The withdrawal of ICs was uniformly agreed to be feasible.

Techniques of assessing small airways dysfunction

The small airways are defined as those less than 2 mm in diameter. They are a major site of pathology in many lung diseases, not least chronic obstructive pulmonary disease (COPD) and asthma. The small airways are frequently involved early in the course of these diseases, with significant pathology demonstrable often before the onset of symptoms or changes in spirometry and imaging. Despite their importance, they have proven relatively difficult to study. This is in part due to their relative inaccessibility to biopsy and their small size which makes their imaging difficult. Traditional lung function tests may only become abnormal once there is a significant burden of disease within them. This has led to the term 'the quiet zone' of the lung. In recent years, more specialised tests have been developed which may detect these changes earlier, perhaps offering the possibility of earlier diagnosis and intervention. These tests are now moving from the realms of clinical research laboratories into routine clinical practice and are increasingly useful in the diagnosis and monitoring of respiratory diseases. This article gives an overview of small airways physiology and some of the routine and more advanced tests of airway function.

Characterization of airway inflammation in patients with COPD using fractional exhaled nitric oxide levels: a pilot study

Objective

To characterize fractional exhaled nitric oxide (FeNO) levels that may be indicative of Th2-mediated airway inflammation in patients with chronic obstructive pulmonary disease (COPD).

Methods

This single-visit, outpatient study was conducted in 200 patients aged 40 years and older with COPD. All patients underwent spirometry and FeNO testing. COPD severity was classified according to the Global initiative for chronic Obstructive Lung Disease (GOLD) 2010 guidelines.

Results

Patients who participated in the study had a mean age of 63.9±11.3 years and a mean smoking history of 46±29 pack years. Patients had a mean forced expiratory volume in 1 second % predicted of 53.9%±22.1%. The percentage of patients classified with COPD severity Stage I, II, III, and IV was 13%, 40%, 39%, and 8%, respectively. In addition, according to current procedural terminology codes, 32% of patients were classified as mixed COPD/asthma, 26% as COPD/emphysema, and 42% as all other codes. The mean FeNO level for all patients was 15.3±17.2 parts per billion (ppb). Overall, 89% of patients had a FeNO <25 ppb, 8% had a FeNO 25–50 ppb, and 3% had a FeNO >50 ppb. The percentages of patients with FeNO in the intermediate or high ranges of FeNO were greatest among patients with mixed COPD/asthma (intermediate, 11.5%; high, 6.6%) compared with COPD/emphysema (intermediate, 8%; high, 0) and all other codes (intermediate, 6.3%; high, 1.3%).

Conclusion

Increases in FeNO were identified in a subset of patients with COPD, particularly in those previously diagnosed with both COPD and asthma. Since FeNO is useful for identifying patients with airway inflammation who will have a beneficial response to treatment with an inhaled corticosteroid, these data may have important implications for the management of COPD patients.

Exhaled nitric oxide as a biomarker in COPD and related comorbidities

Chronic Obstructive Pulmonary Disease (COPD) is defined as a disease characterized by persistent, progressive airflow limitation. Recent studies have underlined that COPD is correlated to many systemic manifestations, probably due to an underlying pattern of systemic inflammation. In COPD fractional exhaled Nitric Oxide (FeNO) levels are related to smoking habits and disease severity, showing a positive relationship with respiratory functional parameters. Moreover FeNO is increased in patients with COPD exacerbation, compared with stable ones. In alpha-1 antitrypsin deficiency, a possible cause of COPD, FeNO levels may be monitored to early detect a disease progression. FeNO measurements may be useful in clinical setting to identify the level of airway inflammation, per se and in relation to comorbidities, such as pulmonary arterial hypertension and cardiovascular diseases, either in basal conditions or during treatment. Finally, some systemic inflammatory diseases, such as psoriasis, have been associated with higher FeNO levels and potentially with an increased risk of developing COPD. In these systemic inflammatory diseases, FeNO monitoring may be a useful biomarker for early diagnosis of COPD development.

The relationship between airflow obstruction, emphysema extent, and small airways function in COPD

BACKGROUND

The severities of COPD (FEV(1) % predicted) and airflow obstruction (FEV(1)/FVC) are considered to be due to both emphysema and small airways disease. To our knowledge, this has not been previously confirmed by combined measurements of emphysema and of small airway function. We hypothesized that small airways disease and emphysema extent contribute independently to the severity of both COPD and airflow obstruction.

METHODS

Twenty-six subjects with COPD underwent measurements with forced oscillation technique (FOT) at 6 Hz and single-breath nitrogen washout. Respiratory system resistance, respiratory system reactance (Xrs), and expiratory flow limitation (EFL) index (measured as mean inspiratory Xrs − expiratory Xrs) were derived from FOT. Closing volume/vital capacity (CV/VC) was derived from the washout. Emphysema extent was measured as low attenuation areas < -910 Hounsfield units, expressed as a percentage of CT scan lung volume from multislice CT scans taken at total lung capacity.

RESULTS

Subjects were aged (mean ± SD) 69.6 ± 8.0 years. Postbronchodilator FEV(1) was 64.8 ± 19.8% predicted, and diffusing capacity of lung for carbon monoxide was 50.7 ± 15.8% predicted. Emphysema extent was 22.6% ± 15.0% CT scan volume. CV/VC was 16.9% ± 7.9%; Xrs, -3.72 ± 3.03 cm H(2)O/L/s; and EFL index, 3.88 ± 3.93 cm H(2)O/L/s. In multiple regression analyses, FEV(1)/FVC was predicted by both emphysema and CV/VC (model r(2) = 0.54, P < .0001) whereas FEV(1) % predicted was predicted by emphysema and EFL index (model r(2) = 0.38, P = .0014).

CONCLUSIONS

The severities of COPD and airflow obstruction are independently predicted by both small airways disease and emphysema extent.

Update on exhaled nitric oxide in pulmonary disease

The ability to assess the inflammatory status of a patient's airway using a noninvasive method is the ideal situation for clinicians. Owing in part to the relationship between the levels of exhaled nitric oxide to inflammation and the ease of the technique, the measurement of the fraction of exhaled nitric oxide (F(E)NO) has achieved considerable attention, particularly with respect to asthma. A multitude of studies have shown that when measured in exhaled air, this unique molecule has the potential to have both diagnostic and therapeutic roles in the clinical setting for many pulmonary diseases. The incorporation of F(E)NO into asthma management and treatment algorithms may help shed further insight on the current control and future risk of patients. Research is ongoing to determine the biology and the benefits of the use of F(E)NO in respiratory conditions in addition to asthma. This review will briefly outline the pathophysiology of nitric oxide, the measurement of F(E)NO and the potential clinical uses of F(E)NO in asthma and a number of other respiratory diseases. Despite its promise, until further research is conducted, the use of F(E)NO cannot be recommended for routine clinical management of respiratory diseases at present, but should be considered as an adjuvant to help guide therapy in certain patients with asthma and in those with eosinophilic bronchitis.

Clinical phenotypes of COPD: identification, definition and implications for guidelines

The term phenotype in the field of COPD is defined as "a single or combination of disease attributes that describe differences between individuals with COPD as they relate to clinically meaningful outcomes". Among all phenotypes described, there are three that are associated with prognosis and especially are associated with a different response to currently available therapies. There phenotypes are: the exacerbator, the overlap COPD-asthma and the emphysema-hyperinflation. The exacerbator is characterised by the presence of, at least, two exacerbations the previous year, and on top of long-acting bronchodilators, may require the use of antiinflammatory drugs. The overlap phenotype presents symptoms of increased variability of airflow and incompletely reversible airflow obstruction. Due to the underlying inflammatory profile, it uses to have a good therapeutic response to inhaled corticosteroids in addition to bronchodilators. Lastly, the emphysema phenotype presents a poor therapeutic response to the existing antiinflammatory drugs and long-acting bronchodilators together with rehabilitation are the treatments of choice. Identifying the peculiarities of the different phenotypes of COPD will allow us to implement a more personalised treatment, in which the characteristics of the patients, together with their severity will be key to choose the best treatment option.

Improvement of Airflow Limitation by Fluticasone Propionate/Salmeterol in Chronic Obstructive Pulmonary Disease: What is the Specific Marker?

Backgrounds: Inhaled corticosteroids (ICS)/inhaled long-acting beta₂-agonists (LABA) combination drugs are widely used for the long-term management of chronic obstructive pulmonary disease (COPD). However, COPD is a heterogeneous condition and treatment with ICS is associated with a higher risk of pneumonia. The identification of a specific marker for predicting the efficacy of ICS/LABA on pulmonary function would be useful in the treatment of COPD. Methods: Fourteen COPD patients receiving tiotropium therapy participated consecutively. The relationship between the baseline exhaled nitric oxide (FE_NO) levels as well as serum markers and changes in pulmonary function by fluticasone propionate (FP)/salmeterol (SAL) were analyzed. Results: FP/SAL therapy significantly improved forced vital capacity, forced expiratory volume in 1 s (FEV₁), and the third phase slope of the single nitrogen washout curve (ΔN₂) as well as the FE_NO level. The baseline FE_NO levels and positive specific IgE (atopy+) were significantly associated with airway obstructive changes assessed by FEV₁ and ΔN₂. A baseline FE_NO level >35 ppb yielded 80.0% sensitivity and 66.7% specificity for identifying the subjects with significant improvement in FEV₁ (greater than 200 mL). An atopy+ yielded 60.0% sensitivity and 88.9% specificity for an improvement in FEV₁. When combined with FE_NO > 35 ppb and atopy+, it showed 40% sensitivity and 100.0% specificity for FEV₁ improvement. Alternatively, COPD subjects with FE_NO ≤ 35 ppb and atopy− did not show significant improvement in FEV₁. Conclusion: Combining FE_NO and specific IgE may be a useful marker for predicting the response to ICS/LABA on airflow limitation in COPD.

[Role of exhaled nitric oxide in predicting steroid response in chronic obstructive pulmonary disease]

Exhaled nitric oxide is the most extensively studied exhaled biomarker. In patients with stable chronic obstructive pulmonary disease exhaled nitric oxide level appears to be normal or only slightly elevated. As exhaled nitric oxide is a good surrogate marker for eosinophilic airway inflammation and eosinophilic inflammation is steroid responsive, patients with elevated exhaled nitric oxide levels may benefit more from a short course of inhaled or systemic corticosteroid treatment. In acute exacerbation most studies report elevated exhaled nitric oxide levels that decrease along with treatment. More importantly, exhaled nitric oxide levels at exacerbation correlate with functional improvements after treatment suggesting the possibility of a role for exhaled nitric oxide in predicting the response to treatment. In conclusion, assessment of airway inflammation using exhaled nitric oxide may identify a subgroup of patients with chronic obstructive pulmonary disease that is likely to benefit from corticosteroid treatment.

Vitamin D and responses to inhaled fluticasone in severe chronic obstructive pulmonary disease

Background

Patients with chronic obstructive pulmonary disease (COPD) demonstrate variable responses to inhaled corticosteroids (ICS). The factors contributing to this variability are not well understood. Data from patients with asthma have suggested that low 25-hydroxyvitamin D [25(OH)D] levels contribute to a lack of ICS response in asthma. The objective of this study was to determine whether serum levels of 25(OH)D were related to ICS responses in patients with COPD.

Methods

A total of 60 exsmokers with severe COPD (mean forced expiratory volume in one second [FEV₁] 1.07 L, 36% of predicted) spent 4 weeks free of any ICS, followed by 4 weeks of ICS use (fluticasone propionate 500 μg twice daily). Spirometry was performed prior to and after 4 weeks of ICS use. Blood 25(OH)D levels were measured prior to ICS use and examined for relationships to changes in FEV₁ following the 4 weeks of ICS use.

Results

The mean 25(OH)D level was 23.3 ± 9.3 ng/mL. There was a high prevalence of vitamin D insufficiency (35%) and deficiency (40%). There was no relationship between baseline 25(OH)D and changes in FEV₁ following 4 weeks of ICS.

Conclusion

Baseline 25(OH)D does not contribute to the variation in short-term FEV₁ responses to ICS in patients with severe COPD.

Exhaled nitric oxide in pulmonary diseases: a comprehensive review

The upregulation of nitric oxide (NO) by inflammatory cytokines and mediators in central and peripheral airway sites can be monitored easily in exhaled air. It is now possible to estimate the predominant site of increased fraction of exhaled NO (FeNO) and its potential pathologic and physiologic role in various pulmonary diseases. In asthma, increased FeNO reflects eosinophilic-mediated inflammatory pathways moderately well in central and/or peripheral airway sites and implies increased inhaled and systemic corticosteroid responsiveness. Recently, five randomized controlled algorithm asthma trials reported only equivocal benefits of adding measurements of FeNO to usual clinical guideline management including spirometry; however, significant design issues may exist. Overall, FeNO measurement at a single expiratory flow rate of 50 mL/s may be an important adjunct for diagnosis and management in selected cases of asthma. This may supplement standard clinical asthma care guidelines, including spirometry, providing a noninvasive window into predominantly large-airway-presumed eosinophilic inflammation. In COPD, large/central airway maximal NO flux and peripheral/small airway/alveolar NO concentration may be normal and the role of FeNO monitoring is less clear and therefore less established than in asthma. Furthermore, concurrent smoking reduces FeNO. Monitoring FeNO in pulmonary hypertension and cystic fibrosis has opened up a window to the role NO may play in their pathogenesis and possible clinical benefits in the management of these diseases.

Repeatability of exhaled nitric oxide measurements in patients with COPD

The assessment of the presence of eosinophilic airway inflammation may help in predicting the steroid response in subjects with respiratory symptoms. Unlike patients with asthma, only a subset of patients with chronic obstructive pulmonary disease (COPD) benefits from steroid treatment. Fractional exhaled nitric oxide (FENO) is a useful surrogate marker for eosinophilic airway inflammation, but data on the repeatability of FENO measurements in COPD needed for the assessment of significant change are insufficient. The aim of this study was to assess the short-term repeatability of FENO measurement in subjects with moderate to very severe chronic airway obstruction compared to that in healthy subjects. We studied 20 patients with stable COPD and 20 healthy subjects, and determined FENO (flow rate 50 ml s(-1) ) three times: at baseline, 10 min and 24 h after baseline. Spirometry was performed on the first study day after the FENO measurements. The median FENO concentration in patients with COPD was 15·6 ppb, and in healthy subjects, 15·2 ppb. The coefficient of variation (CoV) for 24-h measurements was 12·4% in COPD patients, and 15·9% in healthy subjects. Among COPD patients with global initiative for chronic obstructive lung disease stage 2 disease, the CoV was 13·7%, and among those with stage 3-4 disease, 10·5%. The findings indicate that the short-term repeatability of FENO measurement in patients with moderate to very severe COPD is equally good as in healthy subjects. A change in FENO exceeding 24% is likely to reflect a minimum measurable change in COPD.

Exhaled nitric oxide in diagnosis and management of respiratory diseases

The analysis of biomarkers in exhaled breath constituents has recently become of great interest in the diagnosis, treatment and monitoring of many respiratory conditions. Of particular interest is the measurement of fractional exhaled nitric oxide (FENO) in breath. Its measurement is noninvasive, easy and reproducible. The technique has recently been standardized by both American Thoracic Society and European Respiratory Society. The availability of cheap, portable and reliable equipment has made the assay possible in clinics by general physicians and, in the near future, at home by patients. The concentration of exhaled nitric oxide is markedly elevated in bronchial asthma and is positively related to the degree of esinophilic inflammation. Its measurement can be used in the diagnosis of bronchial asthma and titration of dose of steroids as well as to identify steroid responsive patients in chronic obstructive pulmonary disease. In primary ciliary dyskinesia, nasal NO is diagnostically low and of considerable value in diagnosis. Among lung transplant recipients, FENO can be of great value in the early detection of infection, bronchioloitis obliterans syndrome and rejection. This review discusses the biology, factors affecting measurement, and clinical application of FENO in the diagnosis and management of respiratory diseases.