Antioxidants and protein carbonyls in bronchoalveolar lavage fluid of children: normal data

Oxidative stress in early cystic fibrosis lung disease is exacerbated by airway glutathione deficiency

Neutrophil-derived myeloperoxidase (MPO) is recognized as a major source of oxidative stress at the airway surface of a cystic fibrosis (CF) lung where, despite limited evidence, the antioxidant glutathione is widely considered to be low. The aims of this study were to establish whether oxidative stress or glutathione status are associated with bronchiectasis and whether glutathione deficiency is inherently linked to CF or a consequence of oxidative stress. MPO was measured by ELISA in 577 bronchoalveolar lavage samples from 205 clinically-phenotyped infants and children with CF and 58 children without CF (ages 0.2-6.92 years). Reduced glutathione (GSH), oxidized glutathione species (GSSG; glutathione attached to proteins, GSSP; glutathione sulfonamide, GSA) and allantoin, an oxidation product of uric acid, were measured by mass spectrometry. The odds of having bronchiectasis were associated with MPO and GSSP. GSH was low in children with CF irrespective of oxidation. Oxidized glutathione species were significantly elevated in CF children with pulmonary infections compared to uninfected CF children. In non-CF children, infections had no effect on glutathione levels. An inadequate antioxidant response to neutrophil-mediated oxidative stress during infections exists in CF due to an inherent glutathione deficiency. Effective delivery of glutathione and inhibition of MPO may slow the development of bronchiectasis.

Urates in exhaled breath condensate as a biomarker of control in childhood asthma

OBJECTIVE

The aim of this study was to (1) investigate the possibility to use urates in exhaled breath condensate (EBC) as a biomarker of airway inflammation and control in childhood asthma and (2) explore their association with other biomarkers of airway inflammation and clinical indices of asthma control (Asthma Control Test [ACT], quality of life [PAQLQ], lung function, prn beta-agonist use, time from last exacerbation [TLE].

METHODS

This cross-sectional study comprised 103 consecutive patients (age 6-18 years) divided in groups of uncontrolled ([NC], n = 53) and controlled asthma ([C], n = 50). Measured lung function and biomarkers included: spirometry, eosinophilic cationic protein (ECP), high-sensitivity C-reactive protein (hs-CRP), exhaled NO (FENO), pH and urates in EBC and exhaled breath temperature (EBT).

RESULTS

Statistically significant differences were found between groups for EBC urates, EBC pH and EBT (NC versus C: EBC urates, median [IQR], µmol/L; 10 [6] versus 45 [29], p < 0.001; EBC pH, mean [SD], 7.2 [0.17] versus 7.33 [0.16], p = 0.002; EBT mean [SD], °C; 34.26 [0.83], versus 33.90 [0.60], p = 0.014). EBC urates showed significant association with TLE and FENO (r = 0.518, p < 0.001; r = 0.369, p = 0.007, respectively) in NC, and EBC pH (r = 0.351, p < 0.001), FEV1 (r = 0.222, p = 0.024), ACT (r = 0.654, p < 0.001), PAQLQ (r = 0.686, p < 0.001) and prn salbutamol use (r = -0.527, p < 0.001) in all asthmatics.

CONCLUSION

In our study, EBC urates were found to be the best single predictor of asthma control and underlying airway inflammation. Our results provide evidence supporting the potential utility to use EBC urates as an additional non-invasive biomarker of control in childhood asthma.

Increased oxidative stress in children with post infectious Bronchiolitis Obliterans

BACKGROUND

There is increasing evidence that oxidative stress is involved in the development and severity of bronchiolitis obliterans occurring in post-transplant patients. In developing countries, the most common form of bronchiolitis obliterans occurs after severe lung infection, mainly caused by adenovirus. However, the oxidative status in the lungs of children with post infectious bronchiolitis obliterans is unknown.

METHODS

The aim of this study was to measure the oxidant (8-isoprostane and protein carbonyls) and antioxidant (catalase and glutathione peroxidase) activity in the bronchoalveolar lavage fluid of 21 children with post-infectious bronchiolitis obliterans, and to correlate oxidant/antioxidant level with lung function. Lung function was assessed by spirometry and plethysmography, one week prior to fiberbronchoscopy.

RESULTS

There was a markedly increased oxidative stress (lipid and protein oxidation) in the bronchoalveolar lavage fluid, and a notorious impairment of lung function demonstrating moderate-severe distal airway narrowing. There was not a significant correlation between the level of oxidants or antioxidants and lung function. There was a consistent antioxidants/oxidants pattern characterised by markedly increased 8-isoprostane and carbonyls, increased GPx and normal catalase activity.

CONCLUSION

The present study shows for the first time that children with post-infectious bronchiolitis obliterans have a markedly increased oxidative stress in their lungs.

The effects of tobacco smoke exposure on respiratory health in school-aged children

The effects of tobacco smoke exposure on the respiratory health of school-aged children relate to persisting effects of exposure to tobacco smoke during pregnancy and early infancy, passive exposure to environmental tobacco smoke in the home and elsewhere, and active smoking during later childhood. Much of the current evidence comes from cross-sectional and longitudinal observational studies and suggests that, for asthma and pulmonary function outcomes, the strongest associations are with smoke exposure in pregnancy and early childhood, although independent effects of later exposure are reported. Exposure in later childhood to environmental tobacco smoke is associated with increased respiratory symptoms, although for some of these, the effect appears to diminish with increasing age of the child. There is currently a paucity of evidence on the long-term adverse respiratory consequences of active smoking by children and adolescents, but such evidence there is suggests that these may be substantial.

Oxidized vitamin E and glutathione as markers of clinical status in asthma

BACKGROUND & AIMS

Antioxidant status is disturbed in asthma. Measurement of both oxidized and reduced forms of antioxidants provides important information regarding the oxidant/antioxidant balance. The aim of this study was to investigate the clinical relevance of key antioxidants (alpha-tocopherol and glutathione) in asthma, by measuring the oxidized and reduced forms, in the airways (induced sputum) and systemically (peripheral blood).

METHODS

This cross-sectional study examines stable asthmatics (n=44) and healthy controls (n=31) recruited through John Hunter Hospital, NSW, Australia. We collected peripheral blood and induced sputum during hypertonic saline challenge. Alpha-tocopherol and alpha-tocopherol quinone were measured by HPLC. Total glutathione and glutathione disulfide were determined by a colorimetric assay.

RESULTS

Plasma alpha-tocopherol was low in asthma versus controls. Subjects with asthma had higher levels of whole blood alpha-tocopherol quinone and %alpha-tocopherol quinone than controls and %alpha-tocopherol quinone correlated with asthma control (p=0.009). Sputum supernatant levels of total, reduced and oxidized glutathione were elevated in asthma versus controls. Oxidized glutathione in sputum supernatant negatively correlated with FEV(1)/FVC% (p=0.029).

CONCLUSIONS

In asthma, both systemic and airway antioxidant defences are disturbed. Oxidized forms of alpha-tocopherol and glutathione are associated with clinical asthma outcomes, and should be further investigated as a tool for monitoring asthma.

Vitamins and respiratory disease: antioxidant micronutrients in pulmonary health and disease

The lungs are continually exposed to relatively-high O(2) tensions, and as such, in comparison with other organs, they represent a unique tissue for the damaging effects of oxidant attack. At particular times during a lifetime this every day challenge may increase exponentially. The first oxidative insult occurs at birth, when cells are exposed to a sudden 5-fold increase in O(2) concentration. Thereafter, the human lung, from infancy through to old age, can be subjected to deleterious oxidative events as a consequence of inhaling environmental pollutants or irritants, succumbing to several pulmonary diseases (including infant and adult respiratory distress syndromes, asthma, chronic obstructive pulmonary disease, cystic fibrosis and cancer) and receiving treatment for these diseases. The present paper will review the concept that consumption of a healthy diet and the consequent ability to establish and then maintain adequate micronutrient antioxidant concentrations in the lung throughout life, and following various oxidative insults, could prevent or reduce the incidence of oxidant-mediated respiratory diseases. Furthermore, the rationale, practicalities and complexities of boosting the antioxidant pool of the respiratory-tract lining fluid in diseases in which oxidative stress is actively involved, by direct application to the lung v. dietary modification, in order to achieve a therapeutic effect will be discussed.

Protein oxidation by chronic pulmonary diseases in children

The oxidation of proteins may play an important role in the pathogenesis of chronic inflammatory lung diseases, and may contribute to lung damage. However, the extent of oxidation and the distribution among proteins are not known for most pediatric lung diseases. In this work, protein oxidation was assessed as protein carbonyls. Bronchoalveolar lavages (BAL) from children with chronic lung diseases were investigated by dot-blot assay for content and for pattern of distribution of oxidized proteins by two-dimensional (2D) electrophoresis and Western blotting. Significantly higher levels of protein oxidation than in healthy controls were determined in groups of patients with interstitial lung disease, gastro-esophageal reflux disease, and pulmonary alveolar proteinosis. The proteins most sensitive to oxidation were serum albumin, surfactant protein A, and alpha1-antitrypsin. Our data show increased oxidative stress in lungs of children with chronic pulmonary diseases, with significant interindividual variations. The extent of protein oxidation was proportional to the count of neutrophilic granulocytes in BAL fluid. These findings strongly support the concept that an abundance of reactive oxygen species produced during neutrophilic inflammation may be a deleterious factor, leading to pulmonary damage in these patients.

New insight into the pathophysiology of severe hypothyroidism in an infant with multiple hepatic hemangiomas

We report on an infant with severe acquired hypothyroidism resulting from both increased activity of type 3 iodothyronine deiodinase and increased production of TSH-like hormone from hepatic hemangiomas. The combination of these two mechanisms in a patient with hepatic hemangiomas has not been reported previously.

Ascorbic acid in nasal and tracheobronchial airway lining fluids

Ascorbic acid (AA) is thought to be an important antioxidant in the respiratory tract, whose regulation is yet to be fully characterized. We investigated whether AA in respiratory tract lining fluids (RTLFs) can be augmented by oral supplementation with AA. Plasma, nasal lavage fluids (NLFs), induced sputum (IS), and saliva were analyzed for AA immediately before and 2 h after ingestion of 2 g of AA in 13 healthy subjects. Concentrations of AA (median and range) were 52.5 (16.0-88.5), 2.4 (0.18-4.66), 2.4 (0.18-6.00), and 0.55 (0.18-18.90) micromol/l, respectively. Two hours after ingestion of AA, plasma AA increased 2-fold (p = .004), NLF AA increased 3-fold (p = .039), but IS and saliva AA did not increase. As AA concentrations in saliva and tracheobronchial secretions were low compared with other common extracellular components (such as urate), we evaluated the fate of AA in these fluids. Addition of AA to freshly obtained saliva or IS resulted in rapid depletion, which could be largely prevented or reversed by sodium azide or dithiothreitol. These findings suggest that oxidant-producing systems in saliva and airway secretions, such as heme peroxidases and other oxidizing substances, rapidly consume AA. Whereas oral supplementation resulted in detectable increases of AA in NLFs, its levels in tracheobronchial lining fluid, as measured by IS, were unaffected and remained relatively low, suggesting that AA may play a less significant antioxidant role in this compartment as compared with most other extracellular compartments.

Relationship between dietary antioxidants and childhood asthma: more epidemiological studies are needed

Approximately 15 million Americans including over 5 million children suffer from asthma, the most common chronic disease in childhood. The prevalence of pediatric asthma has risen sharply over the past four decades, with the sharpest increases occurring in children younger than 6 years and in urban, predominantly minority, populations. The reasons for this dramatic increase are not yet clear. Recent epidemiological studies indicate a higher prevalence of dietary antioxidant deficiency among asthmatics patients. However, the results of these studies are inconsistent or even contradictory. Epidemiological studies with robust design and use of novel epidemiological tools are urgently needed to examine the impact of dietary antioxidants on the incidence of asthma in preschool children. An incidence density case-control study which includes non-atopic controls, who are matched for age, gender, race, study center and sampling time to each asthmatic case will offer a robust study design. A validated food frequency questionnaire and an asthma and atopy severity score can be used to interview the parents of the recruited children. Risk set sampling may enable us to explore possible associations between the type and quantity of dietary antioxidants and the development and severity of asthma in such an epidemiological study.

Antioxidants and oxidative stress in BAL fluid of atopic asthmatic children

Earlier studies in adults have indicated that increased oxidative stress may occur in the blood and airways of asthmatic subjects. Therefore the aim of this study was to compare the concentrations of antioxidants and protein carbonyls in bronchoalveolar lavage fluid of clinically stable atopic asthmatic children (AA, n = 78) with our recently published reference intervals for nonasthmatic children (C, n = 124). Additionally, lipid peroxidation products (malondialdehyde) in bronchoalveolar lavage fluid and several antioxidants in plasma were determined. Bronchoalveolar lavage concentrations (median and interquartile range) of ascorbate [AA: 0.433 (0.294-0.678) versus C: 0.418 (0.253-0.646) micromol/L], urate [AA: 0.585 (0.412-0.996) versus C: 0.511 (0.372-0.687) micromol/L], alpha-tocopherol [AA: 0.025 (0.014-0.031) versus C: 0.017 (0.017-0.260) micromol/L], and oxidized proteins as reflected by protein carbonyls [AA: 1.222 (0.970-1.635) versus C: 1.243 (0.813-1.685) nmol/mg protein] were similar in both groups (p > 0.05 in all cases). The concentration of protein carbonyls correlated significantly with the number of eosinophils, mast cells, and macrophages in AA children only. Concentrations of oxidized proteins and lipid peroxidation products (malondialdehyde) correlated significantly in AA children (r = 0.614, n = 11, p = 0.044). Serum concentrations of ascorbate, urate, retinol, alpha-tocopherol, beta-carotene, and lycopene were similar in both groups whereas alpha-carotene was significantly reduced in asthmatics. Overall, increased bronchoalveolar lavage eosinophils indicate ongoing airway inflammation, which may increase oxidatively modified proteins as reflected by increased protein carbonyl concentrations.