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Circadian variation of urinary eosinophil protein X in asthmatic and healthy children
K Storm van's Gravesande1, J Mattes, T Grüntjens
1University Children's Hospital Freiburg, Freiburg, Germany.
Insights
Urinary eosinophil protein X (EPX) levels show daily fluctuations in children with asthma and healthy controls. Measuring EPX can help monitor asthma treatment effectiveness when these circadian variations are considered.
Area of Science:
- Pediatric Pulmonology
- Biomarker Research
- Circadian Biology
Background:
- Urinary eosinophil protein X (EPX) is a potential noninvasive marker for bronchial inflammation in pediatric asthma.
- Circadian variations in eosinophil activity may impact urinary EPX excretion patterns.
Purpose of the Study:
- To investigate the circadian variation of eosinophilic activation using urinary EPX measurements.
- To assess the utility of urinary EPX in monitoring bronchial inflammation in asthmatic children before and after corticosteroid treatment.
Main Methods:
- Radioimmunoassay was used to measure urinary EPX levels (microg/mmol creatinine) in morning and afternoon samples.
- Evaluated 22 stable asthmatic children and 16 nonatopic, nonasthmatic controls for circadian variation.
- Analyzed EPX excretion in children with chronic asthma and acute exacerbations before and after treatment.
Main Results:
- Urinary EPX excretion was significantly higher in morning samples compared to afternoon samples in both asthmatic children and controls (P < 0.0001).
- Anti-inflammatory treatment with inhaled corticosteroids led to a significant decrease in EPX excretion in children with chronic asthma (P = 0.02).
- EPX levels were significantly reduced 3 months after discharge in children treated for acute asthma exacerbations (P = 0.02).
Conclusions:
- Urinary EPX excretion exhibits significant circadian variation in children, both with and without asthma.
- Urinary EPX is a valuable tool for monitoring therapeutic response in pediatric asthma, provided its daily rhythm is accounted for.
Background:
It is suggested that urinary eosinophil protein X (EPX) is a noninvasive tool to monitor bronchial inflammation in asthmatic children. However, circadian variation of the number and activation of eosinophils might possibly influence urinary EPX excretion.
Objective:
Measurements of urinary EPX (radioimmunoassay) were used to investigate circadian variation of eosinophilic activation and to monitor bronchial inflammation in children with asthma before and after treatment with corticosteroids.
Methods:
Urinary EPX excretion (microg/mmol creatinine) was measured in the morning and afternoon in 22 stable asthmatics and in 16 nonatopic, nonasthmatic controls to investigate circadian variation. Additionally, EPX excretion in the afternoon was analysed in 21 children with chronic asthma before and after 6 weeks of treatment with inhaled corticosteroids, and in seven children within 24 h of admission due to an asthma exacerbation and again 3 months after discharge.
Results:
EPX excretion in the first morning urine sample of the day compared with the afternoon urine sample was significantly higher both in children with asthma (n = 22; mean +/- standard deviation: 179.7 +/- 97.3 vs 60.9 +/- 40.7 microg/mmol creatinine, P = 0.0001) and in nonatopic nonasthmatic controls (n = 16; 114.5 +/- 57.1 vs 53.4 +/- 29.0 microg/mmol creatinine, P = 0.0001). EPX excretion decreased significantly after 6 weeks of anti-inflammatory treatment in the group of children with chronic asthma (n = 21; 124.7 +/- 84.6 vs 87. 5 +/- 61.9 microg/mmol creatinine, P = 0.02) and in the group of children with an acute asthma exacerbation 3 months after discharge (n = 7; 233.2 +/- 174.5 vs 75.8 +/- 59.5 microg/mmol creatinine, P = 0.02).
Conclusion:
This study suggests a circadian variation of EPX excretion in children with asthma and in nonatopic, nonasthmatic controls. Measurement of EPX excretion is helpful monitoring therapy in asthmatic children if circadian variation is considered.