Environmental Effects on Fractional Exhaled Nitric Oxide in Allergic Children

Health and Environment Unit, Regional Agency for Environment Protection/ARPA, Sicilia, Corso Calatafimi 217, 90129 Palermo, Italy.
Journal of Allergy 01/2012; 2012(4):916926. DOI: 10.1155/2012/916926
Source: PubMed


Fractional exhaled nitric oxide (FeNO) is a non-invasive marker of airway inflammation in asthma and respiratory allergy. Environmental factors, especially indoor and outdoor air quality, may play an important role in triggering acute exacerbations of respiratory symptoms. The authors have reviewed the literature reporting effects of outdoor and indoor pollutants on FeNO in children. Although the findings are not consistent, urban and industrial pollution-mainly particles (PM(2.5) and PM(10)), nitrogen dioxide (NO(2)), and sulfur dioxide (SO(2))-as well as formaldehyde and electric baseboard heating have been shown to increase FeNO, whilst ozone (O(3)) tends to decrease it. Among children exposed to Environmental Tobacco Smoke (ETS) with a genetic polymorphisms in nitric oxide synthase genes (NOS), a higher nicotine exposure was associated with lower FeNO levels. Finally, although more studies are needed in order to better investigate the effect of gene and environment interactions which may affect the interpretation of FeNO values in the management of children with asthma, clinicians are recommended to consider environmental exposures when taking medical histories for asthma and respiratory allergy. Further research is also needed to assess the effects of remedial interventions aimed at reducing/abating environmental exposures in asthmatic/allergic patients.

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Available from: Giuliana Ferrante, Apr 07, 2014
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    • "FeNO levels in healthy children are below 15 to 25 ppb, depending on several non-disease-related factors, such as: age, gender, height, ethnicity, genetics, self-reported atopy, allergic sensitization, total IgE, time of testing, infections, a nitrate rich diet, exercise, smoking, ambient nitric oxide, time of the day and season and environmental pollution [3,11-14] (Figure  1). All these confounding factors have to be considered when evaluating FeNO levels in clinical setting, because they may influence FeNO values and, consequently, patient’s management [6,15]. "
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    ABSTRACT: Asthma is considered an heterogeneous disease, requiring multiple biomarkers for diagnosis and management. Fractional exhaled nitric oxide in exhaled breath (FeNO) was the first useful non-invasive marker of airway inflammation in asthma and still is the most widely used. The non-invasive nature and the relatively easy use of FeNO technique make it an interesting tool to monitor airway inflammation and rationalize corticosteroid therapy in asthmatic patients, together with the traditional clinical tools (history, physical examination and lung function tests), even if some controversies have been published regarding the use of FeNO to support the management of asthma in children. The problem of multiple confounding factors and overlap between healthy and asthmatic populations preclude the routine application of FeNO reference values in clinical practice and suggest that it would be better to consider an individual "best", taking into account the context in which the measurement is obtained and the clinical history of the patient. Besides, there is still disagreement about the role of FeNO as a marker of asthma control, due to the complexity of balance among the different items involved in its determination and the lack of homogeneity in the population groups studied in the few studies conducted so far. Heterogeneity of problematic severe asthma greatly limits utility of FeNO alone as a biomarker of inflammation to optimize the disease management on an individual basis. None of the studies conducted so far demonstrated that the use of FeNO was better than current asthma guidelines in controlling asthma exacerbations. In summary, there is a large variation in FeNO levels between individuals, which may reflect the natural heterogeneity in baseline epithelial nitric oxide synthase activity and/or the contribution of other noneosinophilic factors to epithelial nitric oxide synthase activity. FeNO is a promising biomarker, but at present some limits are highlighted. We would recommend that further research can be carried out by organizing studies aimed to obtain reliable reference values of FeNO and in order to better interpret FeNO measurements in clinical settings, taking also into account the influence of genetic and environmental factors.
    Full-text · Article · Jul 2013 · Multidisciplinary respiratory medicine
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    • "In another study, which was conducted among 2240 school children from 13 Southern Californian communities, the authors also reported positive effects of short-term PM 2.5 mass, PM 10 mass and O 3 on airway inflammation , indicated by an increase of eNO, independent of asthma status (Berhane et al., 2011). Although most previous studies have concluded that exposure to short-term air pollution leads to an increase of eNO among asthmatic children (La Grutta et al., 2012), null associations had also been found (Liu et al., 2009). In the current study, nonsignificant but positive associations were found between 24 h NO 2 and PM 10 mass with eNO among asthmatic children, one possible interpretation for this might be the number of asthmatic children was not large enough to reach statistical significance. "
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    ABSTRACT: Most previous studies which have investigated the short-term effects of air pollution on airway inflammation, assessed by an increase of exhaled nitric oxide (eNO), have been conducted among asthmatic children. Few studies have considered this potential association among non-asthmatics. Furthermore, although both short- and long-term effects of air pollution on eNO had been reported separately, studies which include both are scarce. We explored associations between 24 h NO2 and PM10 (particles with aerodynamic diameters below 10 μm) mass with eNO in 1985 children (192 asthmatics and 1793 non-asthmatics) aged 10 years and accounted for the long-term effects of air pollution by adjusting for annual averages of NO2, PM10 mass, PM2.5 mass (particles with aerodynamic diameters below 2.5 μm) and PM2.5 absorbance, using data from two German birth cohorts in Munich and Wesel. In total, robust associations between 24 h NO2 and eNO were observed in both single-pollutant (percentage change: 18.30%, 95% confidence interval: 11.63–25.37) and two-pollutant models (14.62%, 6.71–23.11). The association between 24 h PM10 mass and eNO was only significant in the single-pollutant model (9.59%, 4.80–14.61). The same significant associations were also observed in non-asthmatic children, while they did not reach significant levels in asthmatic children. Associations between annual averages of ambient air pollution (NO2, PM10 mass, PM2.5 mass and PM2.5 absorbance) and eNO were consistently null. In conclusion, significantly positive associations were observed between short-term ambient air pollution and eNO. No long-term effects of air pollution on eNO were found in this study.
    Full-text · Article · Jan 2013 · International journal of hygiene and environmental health
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    ABSTRACT: BACKGROUND: Exposure to tobacco smoke is a well-known risk factor for childhood asthma and reduced lung function, but the effect on airway inflammation in preschool-aged children is unclear. OBJECTIVE: To examine the effect of parental smoking on lung function and fractional concentration of exhaled nitric oxide (Feno) in relation to both parental reports and children's urine cotinine concentrations in preschool-aged children with multiple-trigger wheeze. METHODS: A total of 105 3- to 7-year-old children with multiple-trigger wheeze and lung function abnormalities were recruited. Lung function was assessed by impulse oscillometry, and Feno measurements were performed. Exposure to tobacco smoke was determined by parental reports and measurement of children's urinary cotinine concentrations. RESULTS: Forty-three percent of the children were exposed to environmental tobacco smoke according to parental reports. The Feno level was significantly higher in children with a smoking mother (n = 27) than in children with a nonsmoking mother (23.4 vs 12.5 ppb, P = .006). The Feno level expressed as z score and the cotinine level correlated significantly (P = .03). Respiratory resistance at 5 Hz was higher in children exposed to maternal smoking than in others (0.99 vs 0.88 kPas/L, P = .005). Urinary cotinine concentrations reflected well parental reports on their daily smoking and increased relative to the number of cigarettes smoked in the family (P < .01). Atopy was found in 75% of the children, but it was not associated with the Feno value (P = .65). CONCLUSION: Maternal smoking was associated with increased Feno value and poorer lung function in steroid-naive preschool children with multiple-trigger wheeze. Larger controlled trials are needed to generalize the results.
    Full-text · Article · Feb 2013 · The Journal of allergy and clinical immunology
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