Metabolites of L-ARG in Exhaled Breath Condensate and Serum Are Not Biomarkers of Bronchial Asthma in Children

(1) Background: L-arginine (L-ARG) and its metabolites are involved in some aspects of asthma pathogenesis (airway inflammation, oxidative stress, bronchial responsiveness, collagen deposition). Published data indicate that lungs are a critical organ for the regulation of L-ARG metabolism and that alterations in L-ARG metabolism may be significant for asthma. The aim of this study was to assess the levels of L-ARG and its metabolites in pediatric patients with asthma in serum and exhaled breath condensate (EBC) by mass spectrometric analysis and compare them with non-asthmatic children. (2) Methods: Sixty-five children (37 pediatric patients with bronchial asthma and 28 healthy control subjects) aged 6–17 participated in the study. All participants underwent a clinical visit, lung tests, allergy tests with common aeroallergens, and serum and EBC collection. The levels of biomarkers were determined in both serum and EBC. Analytical chromatography was conducted using an Acquity UPLC system equipped with a cooled autosampler and an Acquity HSS T3 column. Mass spectrometric analysis was conducted using the Xevo G2 QTOF MS with electrospray ionization (ESI) in positive ion mode. (3) Results: Asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) levels in serum and EBC did not differ significantly in asthmatic children and healthy control subjects. We found no correlation between forced expiratory volume in one second (FEV1) and L-ARG and its metabolites, as well as between interleukin-4 (IL-4) serum level and L-ARG and its metabolites. Concentrations of ADMA, SDMA, citrulline (CIT), and ornithine (ORN) were higher in serum than EBC in asthmatics and non-asthmatics. By contrast, concentrations of dimethylarginine (DMA) were higher in EBC than serum. ADMA/L-ARG, SDMA/L-ARG, and DMA/L-ARG ratios were significantly higher in EBC than in serum in asthmatics and in non-asthmatics. (4) Conclusions: Serum and EBC concentrations of L-ARG and its metabolites were not an indicator of pediatric bronchial asthma in our study.

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Mass spectrometric analysis of biomarkers and dilution markers in exhaled breath condensate reveals elevated purines in asthma and cystic fibrosis

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.90512.2008 ◽

2009 ◽

Vol 296 (6) ◽

pp. L987-L993 ◽

Cited By ~ 56

Author(s):

Charles R. Esther ◽

Gunnar Boysen ◽

Bonnie M. Olsen ◽

Leonard B. Collins ◽

Andrew J. Ghio ◽

...

Keyword(s):

Mass Spectrometry ◽

Cystic Fibrosis ◽

Exhaled Breath Condensate ◽

Forced Expiratory Volume ◽

Mass Spectrometric ◽

Spectrometric Analysis ◽

Exhaled Breath ◽

Noninvasive Methods ◽

Cross Sectional ◽

Breath Condensate

Exhaled breath condensate (EBC) analyses promise simple and noninvasive methods to measure airway biomarkers but pose considerable methodological challenges. We utilized mass spectrometry to measure EBC purine biomarkers adenosine and AMP plus urea to control for dilutional variability in two studies: 1) a cross-sectional analysis of 28 healthy, 40 cystic fibrosis (CF), and 11 asthmatic children; and 2) a longitudinal analysis of 26 CF children before and after treatment of a pulmonary exacerbation. EBC adenosine, AMP, and urea were readily detected and quantified by mass spectrometry, and analysis suggested significant dilutional variability. Using biomarker-to-urea ratios to control for dilution, the EBC AMP-to-urea ratio was elevated in CF [median 1.3, interquartile range (IQR) 0.7–2.3] vs. control (median 0.75, IQR 0.3–1.4; P < 0.05), and the adenosine-to-urea ratio was elevated in asthma (median 1.5, IQR 0.9–2.9) vs. control (median 0.4, IQR 0.2–1.6; P < 0.05). Changes in EBC purine-to-urea ratios correlated with changes in percent predicted forced expiratory volume in 1 s (FEV1) ( r = −0.53 AMP/urea, r = −0.55 adenosine/urea; P < 0.01 for both) after CF exacerbation treatment. Similar results were observed using dilution factors calculated from serum-to-EBC urea ratios or EBC electrolytes, and the comparable ratios of EBC electrolytes to urea in CF and control (median 3.2, IQR 1.6–6.0 CF; median 5.5, IQR 1.4–7.7 control) validated use of airway urea as an EBC dilution marker. These results show that mass spectrometric analyses can be applied to measurement of purines in EBC and demonstrate that EBC adenosine-to-urea and AMP-to-urea ratios are potential noninvasive biomarkers of airways disease.

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