Clinical Utility of Fractional exhaled Nitric Oxide (FeNO) as a Biomarker to Predict Severity of Disease and Response to Inhaled Corticosteroid (ICS) in Asthma Patients

Association of GAB1 gene with asthma susceptibility and the efficacy of inhaled corticosteroids in children

Asthma is a polygenic disease that may onset during childhood. Inhaled corticosteroids (ICS) are the main therapy in asthma, although their efficacy varies among individuals. Nuclear factor κB (NF-κB) is an important target of ICS treatment of asthma. Recent research has reported that GRB2 associated binding protein 1 (GAB1) gene may participate in the pathogenesis of asthma by regulating the NF-κB pathway. Therefore, we used the technique of an improved multiplex ligation detection reaction to sequence GAB1 gene and investigated the involvement of Single-nucleotide variants (SNVs) in GAB1 gene in asthma and ICS efficacy in asthmatic children. We found no differences between asthma cases and controls in allele or genotype frequencies of GAB1. Haplotype analysis showed an increased tendency for AGGAGC frequency in asthma patients compared with controls (OR = 2.69, p = 0.018). The percentage of EOS and genotype distribution of rs1397527 were associated (p = 0.007). The EOS percentage was higher in GT genotype when compared to the GG genotype (5.50 vs 3.00, Bonferroni adjusted p = 0.005). After 12-weeks ICS treatment, GAB1 rs1397527 TT and GT genotype carriers had a smaller change in forced expiratory volume in 1 second/forced vital capacity (FEV1/FVC) than GG carriers (p = 0.009), and rs3805236 GG and AG genotype carriers also had a smaller change in FEV1/FVC than AA carriers (p = 0.025). For ICS response, the frequency of GG genotype of rs1397527 was significantly higher in good responders (p = 0.038). The generalized multifactor dimensionality reduction (GMDR) analysis showed a best significant four-order model (rs1397527, allergen exposure, environmental tobacco smoke exposure, and pet exposure) involving gene-environment interactions (p = 0.001). In summary, we found that GAB1 SNVs were not associated with asthma susceptibility. Haplotype AGGAGC was a risk factor for asthma. GAB1 variants were associated with eosinophils and ICS response in asthmatics. Furthermore, gene-environment interaction was observed.

Promising treatment biomarkers in asthma

Asthma is a highly heterogenous disease which researchers over time have attempted to classify into different phenotypes and endotypes to improve diagnosis, prognosis and treatment. Earlier classifications based on reaction to environmental allergens, age, sex and lung function have evolved, and today, the use of precision medicine guided by biomarkers offers new perspectives on asthma management. Identifying biomarkers that may reveal the underlying pathophysiology of the disease will help to select the patients who will benefit most from specific treatments. This review explores the classification of asthma phenotypes and focuses on the most recent advances in using biomarkers to guide treatment.

Effects of theophylline combined with inhaled corticosteroids on patients with moderate and severe asthma and changes of T lymphocyte subsets in peripheral blood

Introduction

Asthma is a common respiratory disease. Theophylline combined with inhaled corticosteroids (ICS) is a promising therapy for asthma. This study explored the therapeutic effects of ICS combined with theophylline on moderate and severe asthma patients and T lymphocyte subsets (CD3+CD8+ T cells) in peripheral blood.

Material and methods

A total of 202 moderate and severe asthma patients were selected, with 101 treated with theophylline combined with ICS and 101 treated with ICS alone as controls. Lung function [forced expiratory volume within 1 second (FEV1), forced vital capacity (FVC), and peak expiratory flow (PEF)] were tested using a spirometer. Asthma symptom control was evaluated by asthma control tests (ACT). The life quality was evaluated using the Asthma Quality of Life Questionnaire (AQLQ). The number and percentage of CD3+ T, CD3+CD4+ T and CD3+CD8+ T cells in peripheral blood mononuclear cells were assessed by flow cytometry. The correlation between CD3+CD8+ T cells and lung function and asthma control of patients after combination therapy was analyzed by Pearson correlation analysis.

Results

Compared with moderate and severe patients treated with ICS alone, theophylline improved the efficacy of ICS. Theophylline combined with ICS decreased IL-4 and IL-6 levels, and CD3+ T and CD3+CD8+ T cell number and percentage. After combined treatment, CD3+ CD8+ T cells in peripheral blood of patients were positively correlated with lung function and negatively correlated with asthma control.

Conclusions

The additional use of theophylline improved the efficacy of corticosteroids in asthma patient treatment and reduced inflammation level and CD3+ T and CD3+CD8+ T cell contents in peripheral blood.

Biomarkers in Different Asthma Phenotypes

Asthma is the most common respiratory disease. It has multiple phenotypes thatcan be partially differentiated by measuring the disease’s specific characteristics—biomarkers. The pathogenetic mechanisms are complex, and it is still a challenge to choose suitable biomarkers to adequately stratify patients, which became especially important with the introduction of biologicals in asthma treatment. Usage of biomarkers and an understanding of the underlying pathobiological mechanisms lead to the definition of endotypes. Asthma can be broadly divided into two endotypes, T2-high and T2-low. The right combination of various biomarkers in different phenotypes is under investigation, hoping to help researchers and clinicians in better disease evaluation since theindividual approach and personalized medicine are imperative. Multiple biomarkers are superior to a single biomarker.

Differentially expressed serum proteins in children with or without asthma as determined using isobaric tags for relative and absolute quantitation proteomics

Background

Although asthma is one of the most common chronic, noncommunicable diseases worldwide, the pathogenesis of childhood asthma is not yet clear. Genetic factors and environmental factors may lead to airway immune-inflammation responses and an imbalance of airway nerve regulation. The aim of the present study was to determine which serum proteins are differentially expressed between children with or without asthma and to ascertain the potential roles that these differentially expressed proteins (DEPs) may play in the pathogenesis of childhood asthma.

Methods

Serum samples derived from four children with asthma and four children without asthma were collected. The DEPs were identified by using isobaric tags for relative and absolute quantitation (iTRAQ) combined with liquid chromatography tandem mass spectrometry (LC-MS/MS) analyses. Using biological information technology, including Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Cluster of Orthologous Groups of Proteins (COG) databases and analyses, we determined the biological processes associated with these DEPs. Key protein glucose-6-phosphate dehydrogenase (G6PD) was verified by enzyme linked immunosorbent assay (ELISA).

Results

We found 46 DEPs in serum samples of children with asthma vs. children without asthma. Among these DEPs, 12 proteins were significantly (>1.5 fold change) upregulated and 34 proteins were downregulated. The results of GO analyses showed that the DEPs were mainly involved in binding, the immune system, or responding to stimuli or were part of a cellular anatomical entity. In the KEGG signaling pathway analysis, most of the downregulated DEPs were associated with cardiomyopathy, phagosomes, viral infections, and regulation of the actin cytoskeleton. The results of a COG analysis showed that the DEPs were primarily involved in signal transduction mechanisms and posttranslational modifications. These DEPs were associated with and may play important roles in the immune response, the inflammatory response, extracellular matrix degradation, and the nervous system. The downregulated of G6PD in the asthma group was confirmed using ELISA experiment.

Conclusion

After bioinformatics analyses, we found numerous DEPs that may play important roles in the pathogenesis of childhood asthma. Those proteins may be novel biomarkers of childhood asthma and may provide new clues for the early clinical diagnosis and treatment of childhood asthma.

Association Between FeNO, Total Blood IgE, Peripheral Blood Eosinophil and Inflammatory Cytokines in Partly Controlled Asthma

Background

Fractional exhaled nitric oxide (FeNO) is a convenient to use biomarker of airway inflammation. However, the mutual relationship between FeNO, peripheral blood eosinophil, total immunoglobulin E (IgE) and inflammatory cytokines showed some controversy.

Objective

This study was carried out to determine the accuracy of peripheral blood eosinophil and total IgE to detect eosinophilic airway inflammation as determined by two FeNO cutoff points. The correlation between FeNO, peripheral blood eosinophil, total IgE and certain inflammatory cytokines was also examined.

Methods

Seventy-six patients with partly controlled asthma performed the following tests on the same day: FeNO, pulmonary function tests (PFTs), peripheral blood eosinophils, total IgE, and inflammatory cytokine assay. The correlation between these markers was investigated and the diagnostic accuracy of peripheral blood eosinophils and total IgE to identify eosinophilic asthma phenotype was calculated using receiver operating characteristics area under the curve (ROC AUC).

Results

FeNO was positively correlated with percentage of blood eosinophils (r=0.276, p=0.017) and total blood IgE (r=0.3647; p=0.0013). No relationship between FeNO and serum inflammatory cytokines was detected. AUC of blood eosinophils and total IgE were 57% and 64% at FeNO ≥25 ppb and were 67% and 64% at FeNO >50, respectively. The higher predictive ability was detected at FeNO >50 ppb where the best cutoff point for blood eosinophil % was ≥4.0% (sensitivity 66.7%, specificity 60.0%) and the best cutoff point for total IgE was ≥350 (sensitivity 66.7%, specificity 63.6%).

Conclusion

In patients with partly controlled asthma, peripheral blood eosinophil and total IgE showed equal useful accuracy in predicting eosinophilic airways. However, higher predictive values were reported at FeNO level >50 ppb. FeNO was positively correlated with peripheral blood eosinophil, total IgE but not with any of the studied cytokines.

The Value of FENO Measurement for Predicting Treatment Response in Patients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease

Background

Fractional exhaled nitric oxide (FENO) has been shown to be a marker of airway inflammation in various pulmonary diseases, including chronic obstructive pulmonary disease (COPD). In this study, we assessed the FENO level in patients with acute exacerbations of COPD (AECOPD) and analyzed the predictive value of the FENO level for treatment response.

Methods

Demographic data were collected at admission. FENO, lung function, blood gases, COPD Assessment Test (CAT), and modified Medical Research Council (mMRC) scores were measured at admission and on day 7. At the second visit, the patients were asked to report their health status; scores ranged from 1 to 5, representing "much better", "slightly better", "no change", "slightly worse", and "much worse", respectively. The treatment response was evaluated based on the patient's reported health status (responders were those who reported much better and slightly better) and lung function (responders were those who presented an increase in FEV1 over 200 mL).

Results

A total of 182 patients were recruited into the analysis. The FENO level positively correlated with an increase in FEV1 and FEV1% (r = 0.291, p < 0.001 and r = 0.205, p = 0.005, respectively), but negatively correlated with a decrease in the COPD Assessment Test (CAT) score (r = -0.197, p = 0.008) and patient-reported health status (rho = -0.408, p<0.001). An inverse correlation was observed between FENO concentrations at admission and the length of hospital stay. The cut-off point for differentiating responders, identified by health status, was 18 ppb, with the sensitivity being 89.7% and specificity 88.9%.

Conclusion

FENO levels, determined at hospital admission, are potential to predict the overall treatment response in AECOPD patients, including remission in subjective patient-reported health statuses and, also, improvements in lung function.

Registry Number

ChiCTR-ROC-16,009,087 (http://www.chictr.org.cn/).

A phase 2 study to evaluate the safety, efficacy and pharmacokinetics of DP2 antagonist GB001 and to explore biomarkers of airway inflammation in mild-to-moderate asthma

Background

GB001 is an oral antagonist of the prostaglandin D2 receptor that may inhibit recruitment and activation of airway eosinophils, reducing airway inflammation.

Objective

To assess GB001 safety, efficacy and pharmacokinetics from a Phase 2 study and explore the association between type 2 biomarkers (fractional exhaled nitric oxide and blood eosinophils) and asthma control markers following GB001 administration.

Methods

A randomized, placebo‐controlled, double‐blind study evaluating 36 patients with mild‐to‐moderate atopic asthma. Patients receiving fluticasone propionate ≤500 mcg/day or equivalent were randomized (2:1) to GB001 (30 mg) or placebo once daily for 28 days. Safety, pharmacokinetics, forced expiratory volume in 1 second, asthma control questionnaire and rescue medication use were assessed. Clinical outcomes were analysed post hoc by baseline fractional exhaled nitric oxide (<35 and ≥35 ppb) and blood eosinophil (<250 and ≥250 cells/µL) subgroups.

Results

GB001 was well tolerated and rapidly absorbed with a 14.5‐hour terminal half‐life. Overall, GB001 demonstrated greater improvement relative to placebo in forced expiratory volume in 1 second at Day 28 (102 mL [95% CI: −110, 314]). Greater effects on forced expiratory volume in 1 second were observed in the high baseline fractional exhaled nitric oxide and blood eosinophil subgroups (207 mL [95% CI: −283, 698];133 mL [95% CI: −422, 687], respectively). These effects were observed as early as Day 2 (229 mL [95% CI: −170, 628]; 163 mL [95% CI: −223, 550] for the high baseline fractional exhaled nitric oxide and blood eosinophil subgroups, respectively) and were sustained through treatment completion.

Conclusion and clinical relevance

GB001 was well tolerated, with the estimated half‐life supporting once‐daily (QD) dosing. GB001 may have a rapid and sustained effect on lung function, particularly in patients with type 2 phenotype. Further studies are needed to confirm these findings.

On-Line Analysis of Exhaled Breath Focus Review

On-line analysis of exhaled breath offers insight into a person's metabolism without the need for sample preparation or sample collection. Due to its noninvasive nature and the possibility to sample continuously, the analysis of breath has great clinical potential. The unique features of this technology make it an attractive candidate for applications in medicine, beyond the task of diagnosis. We review the current methodologies for on-line breath analysis, discuss current and future applications, and critically evaluate challenges and pitfalls such as the need for standardization. Special emphasis is given to the use of the technology in diagnosing respiratory diseases, potential niche applications, and the promise of breath analysis for personalized medicine. The analytical methodologies used range from very small and low-cost chemical sensors, which are ideal for continuous monitoring of disease status, to optical spectroscopy and state-of-the-art, high-resolution mass spectrometry. The latter can be utilized for untargeted analysis of exhaled breath, with the capability to identify hitherto unknown molecules. The interpretation of the resulting big data sets is complex and often constrained due to a limited number of participants. Even larger data sets will be needed for assessing reproducibility and for validation of biomarker candidates. In addition, molecular structures and quantification of compounds are generally not easily available from on-line measurements and require complementary measurements, for example, a separation method coupled to mass spectrometry. Furthermore, a lack of standardization still hampers the application of the technique to screen larger cohorts of patients. This review summarizes the present status and continuous improvements of the principal on-line breath analysis methods and evaluates obstacles for their wider application.

[Usefulness of measurement of nitric oxide in exhaled air in diagnostics and treatment of allergic rhinitis and asthma in children and adolescents]

Nitric oxide is produced by enzymes called nitric oxide synthases. It fulfills many important functions in the human body, but produced in excess amount has a proinflammatory activity. Fractional exhaled nitric oxide measurements are used in the diagnosis and monitoring of eosinophilic inflammation in the lower airways, but should not be used as an independent parameter to make a diagnosis of asthma or for the monitoring of asthma treatment. Evaluation of fractional exhaled nitric oxide concentrations is also used to determine the pathogenesis of symptoms in patients with rhinitis. In addition, they are helpful in detecting and monitoring eosinophilic inflammation in the lower respiratory tract that coexists with inflammation in the upper airways. Fractional exhaled nitric oxide concentrations may be abnormal (lowered or elevated) in other chronic diseases, such as cystic fibrosis, primary ciliary dyskinesia and inflammatory bowel diseases. Many factors, e.g. atopy, genetic polymorphisms of NOS, and the lipid profile affect the fractional exhaled nitric oxide measurement. Nasal nitric oxide measurement is useful in assessing the prevalence and severity of eosinophilic inflammation in the upper respiratory tract.

Exhaled nitric oxide as a guiding tool for bronchial asthma: A randomised controlled trial

Background

Evidence regarding the role of non-invasive marker of airway inflammation, fractional exhaled nitric oxide (FeNO) to guide asthma treatment is equivocal. We aimed to evaluate if the use of FeNO to adjust inhaled corticosteroid treatment resulted in reduced daily corticosteroid use and lesser exacerbations.

Methods

100 patients of bronchial asthma in the age group of 12-70 years were randomised to receive inhaled corticosteroids based on either FeNO measurements (n = 50) or as per Global Initiative for Asthma (GINA) guidelines. Follow up was done every 2 months for period of 12 months. Results were compared in terms of mean daily inhaled corticosteroid use and number of exacerbations.

Results

After the follow up period of 12 months, mean daily dose of ICS (SD) required in FeNO group was 267.5 μg (126.29), as opposed to control group in which mean daily dose of steroid was 320.00 μg (138.69). However this observed difference in steroid dose was statistically insignificant (p value = 0.061). The estimated mean (SD) rate of asthma exacerbation experienced in follow up period of 12 months in FeNO group was 0.3 episodes (0.54) per patient per year (95% confidence interval, 0.145-455) and 0.4 episodes (0.61) per patient per year in control group (95% confidence interval, 0.228-572). However this difference in rate of exacerbations between the two study groups was not statistically significant (p = 0.387).

Conclusion

FeNO guided management strategy for asthma did not result in statistically significant reduction in dose of inhaled corticosteroids or number of asthma exacerbations.

Associations between occupational inhalation risks and FeNO levels in airway obstruction patients: results from the National Health and Nutrition Examination Survey, 2007-2012

Purpose

To investigate associations between occupational inhalation risks and fractional exhaled nitric oxide (FeNO) levels in patients with chronic obstructive pulmonary disease (COPD).

Patients and methods

Data of 16,486 subjects who had undergone spirometry with pre-bronchodilator and post-bronchodilator lung function assessment were retrieved from the National Health and Nutrition Examination Survey, 2007–2012 database. After excluding 2,638 subjects with missing spirometry values, data of 13,336 subjects were included for analysis. Factors associated with occupational inhalation, FeNO levels and COPD were analyzed using logistic regression analysis.

Results

COPD was associated with occupational exposures to mineral dusts, organic dusts, exhaust fumes, other fumes, and second-hand smoking (P<0.05). Long-term exposure to these occupational hazards carried significantly higher risk for subjects with COPD than for controls (crude odds ratios [ORs]: mineral dusts: 2.364, organic dusts: 2.427, exhaust fumes: 2.728, other fumes: 2.144). In subgroup analysis, COPD correlated positively with long-term exposures to organic dusts and exhaust fumes in subjects with FeNO ≤50 ppb (ORs 1.361 and 1.314, respectively); conversely, COPD correlated negatively with intermediate to long-term exposures to organic dusts and exhaust fumes in those with FeNO >50 ppb (ORs 0.058 and 0.210, respectively).

Conclusion

Occupational exposures to airborne pollutants carries higher risk of COPD than non-exposure and the risk is higher the longer the duration of exposure. Exposure–response relationships are inconsistent in subjects with suspected asthmatic airway inflammation (FeNO ≥50 ppb). More careful risk assessment is needed in occupational inhalation exposure, since COPD with asthmatic airway inflammation, or asthma-COPD overlapping syndrome, may have the distinguishing features of both COPD and asthma.