Exhaled nitric oxide and its relationship to airway responsiveness and atopy in asthma

Abstract

Exhaled nitric oxide (NO) has attracted increasing interest as a non-invasive marker of airway inflammation. The purpose of this study was to determine whether exhaled nitric oxide in subjects with asthma varied according to their atopic status and to examine its correlation with airway hyperresponsiveness and lung function measurements. Forty patients with asthma and 13 controls participated in the study. Nitric oxide was measured on three occasions with intervals of at least 3 days, using a chemiluminescence method. Airway responsiveness was assessed with methacholine challenge and lung function measurements were made. All subjects recorded peak expiratory flow and kept a symptom diary during a 17-day period. There was no significant difference in lung function measurements, peak expiratory flow or symptom score between the two asthma groups. Atopic patients with asthma had a significantly higher mean amount of exhaled NO than non-atopic subjects with asthma (162 +/- 68 vs. 113 +/- 55 nl min-1; P = 0.03) and the control group (88 +/- 52 nl min-1; P = 0.004). No significant difference was found in the amount of exhaled NO between non-atopic patients with asthma and the controls. In atopic subjects with asthma the mean exhaled NO was significantly correlated to the dose-response slope for methacholine (r = -0.52; P = 0.02), while no such correlation was found in the non-atopic group. In conclusion; in this study, atopic subjects with asthma had higher levels of exhaled NO than non-atopic subjects. Atopic status should be taken into account when measuring levels of exhaled NO in subjects with asthma.

Factors that influence exhaled nitric oxide in Italian schoolchildren

“…This finding is in agreement with the study by Ludviksdottir et al, 21 who did not observe any significant difference in eNO between nonasthmatic control patients and nonatopic adult asthmatic patients. Furthermore, when rhinitis and especially asthma were associated with atopy, we found much greater eNO levels; in fact, median eNO in atopic, asthmatic patients was approximately 4-fold higher than the level of nonatopic, asthmatic patients (Table 2).…”

Measurement of exhaled nitric oxide in children, 2001: E. Baraldi and J.C. de Jongste on behalf of the Task Force

“…The relationship between asthma, atopy and FENO is arguable [111,[119][120][121][122], underscoring the need for careful use of standardized techniques. There is controversy in the literature about the similarity of immunopathology in atopic and nonatopic asthma [123,124].…”

“…There is controversy in the literature about the similarity of immunopathology in atopic and nonatopic asthma [123,124]. Some studies have shown that adults and children who are atopic and asthmatic have higher FENO levels than nonatopic asthmatic subjects [121,122,125], suggesting that this instantaneous test could help develop understanding about the different phenotypes of childhood asthma. However, the relationship between atopy, FENO and airway immunopathology needs further clarification, with close attention paid to the definition of the different asthma phenotypes.…”

Comparison of online single-breath vs. online multiple-breath exhaled nitric oxide in school-age children

“…It is correlated with the expression of inducible NO synthase in airways of atopics, especially individuals with atopic asthma (4,5). In both the clinical and the research settings, eNO aids in discriminating different asthma phenotypes, particularly the atopic vs. the nonatopic form (6,7). Increased in atopic or asthmatic patients and reduced under corticosteroid treatment, eNO has assisted with diagnosis and clinical guidance for pediatric and adult patients alike (8).…”