Exhaled nitric oxide and sputum eosinophil markers of inflammation in asthmatic children

Abstract

The relationship between nitric oxide in exhaled air, levels of sputum eosinophils, sputum eosinophil cationic protein (ECP) and urinary eosinophil protein X (EPX) excretion has not yet been investigated in corticosteroid-dependent childhood asthma.Therefore, taking 25 children with stable asthma (mean age 11.2 yrs) treated with inhaled corticosteroids and nine nonatopic healthy control children (mean age 12.8 yrs) the level of exhaled NO was measured by means of a chemiluminescence analyser before and after sputum induction. This was conducted as a slow vital capacity manoeuvre under standardized conditions with a target flow of 70 mL . s -1 against a resistance of 100 cmH 2 O . L -1 . s. Sputum induction was performed by inhalation of hypertonic saline (3, 4, and 5%) in a standardized manner and a single sample of urine was collected.Exhaled NO (p=0.01), absolute eosinophil cell counts in sputum (p=0.02), sputum ECP (p=0.09) and urinary EPX excretion (p=0.02) were higher in asthmatics compared to control children. Exhaled NO was positively correlated with sputum ECP (r s =0.59, p=0.002), urinary EPX (r s =0.42, p=0.03), and sputum eosinophils (r s =0.30, p=0.15) in the asthmatic children. These correlations appeared to be pronounced after sputum induction, where NO values had decreased (p=0.01). None of the correlations were observed in the group of nonatopic control subjects. Additionally there were significant correlations between sputum ECP and sputum eosinophils (r s =0.69, p< 0.001) as well as between sputum ECP and urinary EPX excretion (r s =0.58, p=0.003) in the asthmatics.Exhaled NO provides information about the degree of eosinophilic airway inflammation and thus appears to be a useful and easy-to-perform inflammatory marker in corticosteroid-dependent asthma. Eur Respir J 1999; 13: 1391±1395.

Circadian Variation of Exhaled Nitric Oxide and Urinary Eosinophil Protein X in Asthmatic and Healthy Children

“…urinary EPX excretion, and eosinophilic airway inflammation in asthmatics (12,24). Hence the circadian variation of FeNo and urinary EPX found in this study may indicate a substantial nocturnal increase in activation of eosinophils as previously investigated in blood samples by Wempe et al (25).…”

Monitoring asthma in children

“…The most extensively studied biomarker is FeNO, which has been reported to reflect both airway and tissue eosinophilia [142][143][144]. FeNO can be measured in a noninvasive standardised way and is an attractive technique for use in children, usually from school age onwards [144][145][146].…”

Guideline-Recommended Fractional Exhaled Nitric Oxide Is a Poor Predictor of Health-care Use Among Inner-city Children and Adolescents Receiving Usual Asthma Care

“…Measurement of F eno as an indicator of pulmonary infl ammation is relatively simple and inexpensive compared with other biomarkers, so there is great interest in the potential role for using F eno data in asthma management. F eno level has been shown to correlate with lung function, sputum eosinophil levels, and methacholine responsiveness, [9][10][11][12][13][14][15][16][17] and, therefore, may provide a noninvasive change of Ն 10 ppb for those with lower categories of infl ammation. We applied this algorithm, modifi ed for pediatric cut points (if F eno level increased by Ն 7 ppb for those with F eno values , 35 ppb or Ն 20% for those with F eno Ն 35 ppb) and found that a "significant" change in F eno level from the previous visit did not predict future health-care use ( Table 5 ).…”

“…These are less likely given prior studies that demonstrate reproducibility of F eno measurements 34,35 and the strong, existing evidence of correlation between eosinophilic airway infl ammation and F eno level. 9,11,[13][14][15][16][17] There were limitations to the study design that warrant consideration. As our study population was limited to children in Baltimore City, results may not be generalizable to other populations.…”