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Antioxidants and protein carbonyls in bronchoalveolar lavage fluid of children: normal data
B C Schock1, I S Young, V Brown
1Department of Clinical Biochemistry, Queen's University of Belfast, Belfast BT12 6BJ, UK.
Insights
This study establishes normal reference ranges for antioxidants and oxidized proteins in children's bronchoalveolar lavage fluid (BAL). It found home heating type influences levels and serum ascorbate correlates with BAL ascorbate.
Area of Science:
- Pediatric Respiratory Medicine
- Oxidative Stress Biomarkers
- Environmental Health
Background:
- Oxidative stress, linked to antioxidant-oxidant imbalances in bronchoalveolar lavage fluid (BAL), is implicated in pediatric respiratory diseases.
- Established normal reference ranges for BAL antioxidants and oxidized proteins in children are currently lacking, hindering clinical assessment.
- Understanding these biomarkers is crucial for diagnosing and managing respiratory conditions in pediatric populations.
Purpose of the Study:
- To determine normal reference ranges for key antioxidants (ascorbate, uric acid, alpha-tocopherol) and a marker of oxidative damage (protein carbonyl) in the BAL fluid of children.
- To investigate the influence of factors such as age, gender, environmental tobacco smoke exposure, home heating type, and atopic status on these BAL fluid biomarkers.
- To explore potential correlations between serum and BAL fluid concentrations of these markers, particularly ascorbate.
Main Methods:
- Recruited 124 children undergoing elective surgery for noninflammatory conditions, categorized into nonasthmatic, nonatopic (N) and nonasthmatic, atopic (NA) groups.
- Performed nonbronchoscopic lavage to collect BAL fluid.
- Quantified concentrations of ascorbate, uric acid, alpha-tocopherol, and protein carbonyls in BAL fluid using established laboratory assays.
Main Results:
- Established 95% reference ranges for BAL ascorbate (0.112-1.897 µmol/L), urate (0.149-2.163 µmol/L), alpha-tocopherol (0.0029-0.066 µmol/L), and protein carbonyls (0.280-4.529 nmol/mg).
- Home heating type (glass-fronted fires vs. oil-fired central heating) significantly influenced BAL ascorbate and urate concentrations.
- Significantly increased BAL alpha-tocopherol was observed in the atopic group (NA) compared to the nonatopic group (N); serum and BAL ascorbate showed a significant positive correlation.
Conclusions:
- This study provides the first reference ranges for BAL antioxidants and protein carbonyls in children, essential for future research and clinical application.
- Environmental factors like home heating type can modulate antioxidant levels in pediatric airways, suggesting potential targets for intervention.
- The correlation between serum and BAL ascorbate supports the hypothesis that vitamin C supplementation may benefit asthma symptoms in children.
Abstract:
Antioxidant-oxidant imbalances in bronchoalveolar lavage fluid (BAL) are thought to contribute to oxidative stress in respiratory disease. However, normal reference ranges for BAL antioxidants and oxidized proteins in children are not available. In this study, we recruited 124 children attending for elective surgery for a noninflammatory condition; 83 were nonasthmatic, nonatopic (N) and 41 were nonasthmatic, atopic (NA). A nonbronchoscopic lavage was performed and ascorbate, uric acid, alpha-tocopherol, and protein carbonyl (as a measure of oxidative damage) concentrations were determined in BAL fluid. The 95% reference range was 0.112-1.897 micromol/L for ascorbate, 0.149-2.163 micromol/L for urate, 0.0029-0.066 micromol/L for alpha-tocopherol, and 0.280-4.529 nmol/mg for protein carbonyls in BAL fluid. Age, gender, and exposure to environmental tobacco smoke did not affect the concentration of ascorbate, urate, alpha-tocopherol, or protein carbonyls. However, in multiple linear regression analyses, the type of home heating (glass-fronted fires or oil-fired central heating) was found to influence ascorbate and urate concentrations in the BAL fluid (ss-coefficient for ascorbate: 0.445, p = 0.031; for urate: 0.114, p = 0.001). There was no significant difference between the N and NA group in BAL fluid concentrations of ascorbate, urate, or protein carbonyls. The alpha-tocopherol concentration was significantly increased in the NA group (p = 0.037). Uric acid and alpha-tocopherol concentrations in BAL fluid and serum were not correlated. Intriguingly, serum and BAL ascorbate concentrations were significantly correlated (r = 0.297, p = 0.018, n = 63), which may offer an explanation for why supplementing the diet with vitamin C can improve asthma symptoms. Further studies will investigate the role of BAL antioxidant concentrations in children with inflammatory respiratory diseases.
