The value of FeNO measurement in asthma management: the motion for Yes, it's NO--or, the wrong end of the Stick!

CTSS contributes to airway neutrophilic inflammation in mixed granulocytic asthma

BACKGROUND

Mixed granulocytic asthma (MGA) is usually associated with poor response to corticosteroid therapy and a high risk of severe asthma. Cathepsin S (CTSS) has been found to play an important role in various inflammatory diseases. This study was aimed to investigate the role of CTSS in MGA.

METHODS

Induced sputum was obtained from healthy subjects and asthma patients. Two murine models of MGA were established using either TDI (toluene diisocyanate) alone or OVA emulsified in CFA. LY3000328, a specific antagonist of CTSS, was therapeutically given to BALB/c mice after airway challenge with TDI or OVA. The effects of recombinant CTSS was tested in vivo, and Akt inhibition was used to explore a possible mechanism for CTSS-induced airway inflammation.

RESULTS

MGA patients have a significant higher sputum CTSS level than the health and subjects with other inflammatory phenotypes, which was positively correlated with sputum level of soluble E-cadherin (sE-cadherin), sputum neutrophils, FeNO, FEF25-75% and glucocorticoid dosage. Allergen exposure markedly increased CTSS level and pharmacological antagonism of CTSS with LY3000328 decreased airway hyperresponsiveness, airway neutrophil accumulation, as well as the release of IL-17 and sE-cadherin in murine models of MGA, yet had no effects on eosinophilic inflammation nor type 2 inflammatory cytokines (IL-4 and IL-5). In addition, intratracheal instillation of recombinant CTSS leads to neutrophil recruitment and overproduction of sE-cadherin in the lung tissues, which could be attenuated by inhibition of Akt signaling.

CONCLUSION

Our data suggested that CTSS contributes to airway neutrophilic inflammation in MGA through an Akt-dependent pathway.

Asthma and Medicines - Long-Term Side-Effects, Monitoring and Dose Titration

Asthma is a major pediatric respiratory morbidity requiring long-term management. A thorough knowledge of long-term medication side-effects in children is, thus, essential for every physician dealing with childhood asthma. Establishing diagnosis and initiating treatment is just a beginning of the journey. Ongoing monitoring is an essential component of comprehensive asthma management programme. Monitoring includes not only assessment of asthma control but also checking for adherence to treatment, technique of inhaler device use, associated co-morbities, if any, and potential environmental exposure. Various tools - both subjective and objective - are available for assessment of asthma control. However, evidence for their optimum use in different settings and patient groups is lacking and monitoring has to be customized depending on available resources and individual patient characteristics. Patient education is an important component of long-term asthma therapy. The ultimate aim is to achieve optimum asthma control i.e., achieve and maintain control of clinical symptoms, decrease future risk to patients (risk of exacerbations, progressive loss of lung function and development of fixed airflow obstruction, adverse effects of medications) and enabling the child to lead a life without restrictions, at lowest possible dose of drugs. This article reviews the side-effects of medications used for long-term management of asthma and discusses current literature on asthma monitoring and dose titration in pediatric population to help the asthma therapist not only prescribe the drugs rationally but also help the family make right choices for treatment.

Can exhaled nitric oxide be a surrogate marker of bronchial hyperresponsiveness to adenosine 5'-monophosphate in steroid-naive asthmatic children?

BACKGROUND

The interrelation between airway inflammation, bronchial hyperresponsiveness (BHR) and atopy remains controversial.

OBJECTIVE

The aim of this study was to document whether exhaled nitric oxide (eNO) may be used as a surrogate marker that predicts BHR to adenosine 5'-monophosphate (AMP) in steroid-naive school children with asthma.

METHODS

This study was a retrospective analysis of steroid-naive school age children with atopic and non-atopic asthma. All patients whose eNO levels had been measured and who had been challenged with both methacholine (MCH) and AMP were included. Receiver operation characteristic analysis was performed, in both the atopic and the non-atopic groups, to evaluate the ability of eNO to detect the BHR to AMP.

RESULTS

One hundred and sixteen patients, sixty-nine (59.5%) of whom had been atopic, were included in the analysis. In the atopic group, eNO values were significantly higher in patients with BHR to AMP compared to those without BHR to AMP (51.9 ± 16.9 p.p.b. vs. 33.7 ± 16.4 p.p.b.; P < 0.001), whereas in the non-atopic group, the differences were not statistically significant (29.7 ± 16.9 p.p.b. vs. 22.6 ± 8.1 p.p.b.; P = 0.152). In the atopic group, eNO levels (R(2) : 0.401; β: 0.092; 95% CI: 1.19-14.42; OR: 7.12; P = 0.008) were found to be the only independent factor for BHR to AMP, whereas none of the parameters predicted BHR to AMP in the non-atopic group. The best cut-off value of eNO that significantly predicts BHR to AMP was 33.3 p.p.b. in the atopic group (P < 0.001), whereas a significant cut-off value for eNO that predicts BHR to AMP was not determined in the non-atopic group (P = 0.142). An eNO ≤ 17.4 p.p.b. has 100% negative predictive values and 100% sensitivity and 60.47% PPV for prediction of BHR to AMP in the atopic group.

CONCLUSIONS

Exhaled NO may be used to predict BHR to AMP in atopic but not in non-atopic steroid-naïve asthmatic children.

FeNO and asthma treatment in children: a systematic review and meta-analysis

Traditional asthma treatments are typically adjusted in children with asthma using symptoms and spirometry. Treatments tailored in accordance to inflammatory markers, such as fraction of exhaled nitric oxide (FeNO) or sputum eosinophils, are increasing in use. This meta-analysis evaluated the potential benefit of incorporating the use of monitoring FeNO with guideline-based management in treating children with asthma. PubMed and Cochrane CENTRAL databases were searched until November 2013 for randomized control trials that investigated the use of FeNO compared with conventional monitoring in managing asthma in children. Included studies had at least 2 intervention groups: one that utilized FeNO and the other that utilized only conventional or standard methods (eg, spirometry, symptoms, and others) to guide treatment. Six studies were included in the meta-analysis comprising 506 subjects whose treatment was monitored using FeNO and 511 subjects who were managed using conventional methods. We found no difference between the FeNO and the conventional groups in FeNO value (95% confidence interval [CI]: -0.31, 0.1), change from baseline in FEV1 (95% CI: -0.07, 0.20), or steroid use (95% CI: -0.67, 1.80). However, the FeNO group was associated with a lower frequency of >1 asthma exacerbation (95% CI: 0.532, 0.895). This meta-analysis suggests that using FeNO to guide treatment decisions has little clinical benefit, although may result in a decrease in asthma exacerbations. Our findings support the use of guideline-based asthma management and diagnosis.

[Determining asthma treatment in children by monitoring fractional exhaled nitric oxide, sputum eosinophils and leukotriene B₄]

Sputum eosinophils and exhaled fractional nitric oxide (FENO) are markers of airway inflammation in asthma. Cytokines, cysteinyl-leukotrienes and leukotriene B4 (LTB4) are responsible for this inflammation. The aim of this study is to determine the usefulness of these markers in monitoring asthma treatment in children. FENO, sputum eosinophils, and LTB4 in induced sputum were performed in 10 children (9-15 years old). These determinations were repeated four months later, after the beginning or an increase in the treatment. FENO values tended to decrease (P=.15), pulmonary function tended to improve (P=.10), and sputum eosinophils decreased (P=.003) compared to the first determination. There were no differences in LTB4 concentrations (P=.88). Sputum eosinophils seem to be more precise than FENO in the monitoring of inflammation in asthmatic children.

Limitations of asthma control questionnaires in the management and follow up of childhood asthma

It is important to achieve asthma control whenever possible in clinical practice. Asthma control questionnaires undoubtedly provide a useful measure of asthma control in research studies but their place in routine clinical practice has yet to be secured. There is considerable variation in the results yielded from different validated asthma control tools. It remains to be seen whether they improve the reliability of reporting of symptoms to health care professionals when compared to verbal reporting. In the presence of sensible care from compassionate and well informed doctors and nurses asthma control questionnaires will not improve outcomes for children. A patient-focused clinical encounter supplemented with lung function measurements and occasional eNO testing has more to offer families and children than control questionnaires and their routine use in the clinic cannot be recommended on the basis of current evidence.

Childhood asthma management guided by repeated FeNO measurements: a meta-analysis

The fraction of exhaled nitric oxide (FeNO) has gained interest as a non-invasive tool to measure airway inflammation in asthma since it reflects allergic inflammation. Recent controlled clinical studies have, however, questioned its role in the management of asthma in children. To assess the clinical value of FeNO in paediatric asthma management, a meta-analysis was performed on the controlled studies of childhood asthma management guided by repeated FeNO measurements, and relevant publications on the confounders of FeNO were reviewed. The data suggests that utilising FeNO to tailor the dose of inhaled corticosteroids in children cannot be recommended for routine clinical practice since there is a danger of excessive inhaled corticosteroid doses in children without meaningful changes in clinical outcomes. Many disease and non-disease related factors (most importantly atopy, height/age and infection) affect FeNO levels which can easily confound the interpretation.

Biomarkers in asthma and allergic rhinitis

A biological marker (biomarker) is a physical sign or laboratory measurement that can serve as an indicator of biological or pathophysiological processes or as a response to a therapeutic intervention. An applicable biomarker possesses the characteristics of clinical relevance (sensitivity and specificity for the disease) and is responsive to treatment effects, in combination with simplicity, reliability and repeatability of the sampling technique. Presently, there are several biomarkers for asthma and allergic rhinitis that can be obtained by non-invasive or semi-invasive airway sampling methods meeting at least some of these criteria. In clinical practice, such biomarkers can provide complementary information to conventional disease markers, including clinical signs, spirometry and PC(20)methacholine or histamine. Consequently, biomarkers can aid to establish the diagnosis, in staging and monitoring of the disease activity/progression or in predicting or monitoring of a treatment response. Especially in (young) children, reliable, non-invasive biomarkers would be valuable. Apart from diagnostic purposes, biomarkers can also be used as (surrogate) markers to predict a (novel) drug's efficacy in target populations. Therefore, biomarkers are increasingly applied in early drug development. When implementing biomarkers in clinical practice or trials of asthma and allergic rhinitis, it is important to consider the heterogeneous nature of the inflammatory response which should direct the selection of adequate biomarkers. Some biomarker sampling techniques await further development and/or validation, and should therefore be applied as a "back up" of established biomarkers or methods. In addition, some biomarkers or sampling techniques are less suitable for (very young) children. Hence, on a case by case basis, a decision needs to be made what biomarker is adequate for the target population or purpose pursued. Future development of more sophisticated sampling methods and quantification techniques, such as--omics and biomedical imaging, will enable detection of adequate biomarkers for both clinical and research applications.

The future in paediatric respirology

The authors were given the charge of providing a vision of the future in paediatric respirology. Themes selected for being ripe for this visionary analysis include bronchopulmonary dysplasia (BPD), asthma, cystic fibrosis (CF), lung infections, obstructive sleep disordered breathing (OSDB) and pulmonary diagnostics and monitoring. A profound reduction or elimination of BPD is seen. Given the strong genetic component of this disease, genetic biomarkers will likely be identified that will permit much earlier recognition of BPD susceptibility and potentially the ability to modify disease course by altering gene expression. The ultimate prevention of BPD will be to prevent prematurity, but recognition of both the genetic basis of BPD and the inflammatory background should lead to improved prevention and therapy. A clear understanding and definition of asthma phenotypes will lead to more specific and targeted therapy, earlier detection and prevention, better monitoring of severity and adherence to therapy, lower mortality and decreased inappropriate diagnosis of asthma. The greatest opportunities in asthma care will likely come through tools to improve adherence to effective therapy. Also, areas are identified where better therapies are needed such as in patients with severe mucus hypersecretion (secretory hyperresponsiveness) especially in those with life-threatening asthma. The future of CF is easier to foresee with early successes seen in clinical trials. After the expected ability to correct the CF transmembrane regulator, care will need to change and additional research will be needed. Additionally, the face of CF is changing with more adults than children presently having the disease. This will necessitate changes to our approach to treating this disease in a fortunately aging population. If we are going to affect the worldwide lung health of children, we will need to address respiratory infections particularly pneumonia, tuberculosis and HIV-associated infections. Preventive, diagnostic and treatment strategies will shape the future face of these problems. The availability of inexpensive, readily available, and rapid molecular techniques to identify true infection (including HIV and tuberculosis) may permit earlier use of effective therapy while preventing the inappropriate use of antibiotics for common viral diseases. Sleep medicine will continue to be an important aspect of paediatric pulmonology. The evaluation of OSDB cannot rely on full-night attended polysomnography due to limited access. Identifying reliable markers of end organ dysfunction in children with OSDB may permit more rapid identification of patients in need of intervention like CPAP and assisted breathing. In addition, management options, as an alternative to adenotonsilectomy, are listed with a call for further research. Pulmonary diagnostics and monitoring will see the development and refinement of tools like the lung clearance index and the analysis of exhaled gases, volatiles and dissolved biomarkers of inflammation as techniques that might help clinicians identify both the initiation of inflammation while it is more amenable to therapy, and to identify more readily the early changes associated with chronic lung diseases in children. The authors hope that these visionary articles will generate comments, arguments, inspiration, and perhaps even motivate funding agencies.

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.

The use of exhaled nitric oxide in the diagnosis of asthma in school children

OBJECTIVES

To evaluate the yield of the fractional exhaled nitric oxide (FeNO) in the diagnosis of asthma compared with spirometry and induced sputum cytologic study in school-age children.

STUDY DESIGN

Consecutive children referred for evaluation of possible asthma were included. At referral, all children completed FeNO measurement, sputum induction for eosinophil count (eos%) and spirometry. The diagnosis of asthma was performed after 18 months with conventional criteria. Receiver operating curves were used to determine cutoff points for disease status, and accuracy was calculated.

RESULTS

A total of 150 children were included: 69 with steroid-naïve asthma, 44 without asthma, and 37 with asthma treated with controllers. FeNO and eos% levels were significantly higher in those with steroid-naïve asthma (P < .0001). The area under the receiver operating curve for FeNO and eos% were very high compared with forced expiratory volume in 1 second (0.906, 0.921, 0.606, respectively). The sensitivity, specificity, and positive and negative predictive values for best cutoff points of FeNO (19 parts per billion) were 80%, 92%, 89%, and 86%, respectively, and were similar to eos% (best cutoff = 2.7%): 81%, 92%, 89%, 85%, respectively.

CONCLUSIONS

FeNO measurement is useful in early diagnosis of pediatric asthma. We suggest considering FeNO measurement in the evaluation of children suspected of having asthma, especially in cases where the diagnosis is not clear.

[Feasibility of FeNO measurement in asthmatic children in the primary care setting. CANON Study]

AIM

Asses the feasibility of exhaled nitric oxide (FeNO) measurement in asthmatic children using a hand-held device in the primary care setting.

METHODS

Multicentre study performed in the paediatric clinics in seven Spanish primary health care centres. Each centre consecutively included 6-14 year-old children with doctor-diagnosed asthma. Children were asked to obtain two valid measurements of FeNO with the hand-held device NIOX MINO (Aerocrine AB, Solna, Sweden). Feasibility analysis included: (a) percentage of children able to perform the manoeuvre, (b) time required to obtain a successful determination, (c) number of attempts needed, and (d) acceptability of the technical procedure by clinical personnel involved in their guidance.

RESULTS

The Study enrolled 151 children. A total of 149 (98.7%) were able to perform the FeNO manoeuvre. The majority (55%) of children had previous experience of using the hand-held device. The Overall median (and Interquartile Range, IQR) of attempts needed to reach a first valid measurement was 2 (1-3) and median (IQR) of time taken was 4 min (3-5). Nurses considered the overall procedure was very easy or easy in 87.8% (teaching) and 86.5% (performing) of children. Children with previous experience performed the manoeuvre in less attempts, less time and more easily than children without experience.

CONCLUSIONS

Measurement of FeNO using NIOX MINO device is technically feasible and acceptable for children and staff in the clinical context of asthma management in primary health care. Previous experience had a positive, learning effect, in teaching and performing the FeNO manoeuvre.