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A comprehensive evaluation of the enzymatic and nonenzymatic antioxidant systems in childhood asthma

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Background

Even though there is ample evidence on the oxidative stress in asthma, there is limited information on the antioxidant defense systems.

Objectives

To conduct a comprehensive evaluation of various components of both enzymatic and nonenzymatic antioxidants in a large group of children with asthma.

Methods

A total of 164 children with mild asthma and 173 healthy children were included in the study. Levels of the enzymes glutathione peroxidase and superoxide dismutase were measured by using ELISA, whereas reduced glutathione, ascorbic acid, α-tocopherol, lycopene, β-carotene, amino acids participating in glutathione synthesis, and amino acids susceptible to oxidation were measured by HPLC. All comparisons were adjusted for atopy, body mass index, smoke exposure, and pet ownership.

Results

Levels of the enzymes glutathione peroxidase and superoxide dismutase and of the nonenzymatic components of the antioxidant system including reduced glutathione, ascorbic acid, α-tocopherol, lycopene, and β-carotene were significantly lower in children with asthma compared with healthy controls (P < .001 for each). Of the amino acids contributing to glutathione synthesis, glycine and glutamine were significantly lower in children with asthma (P < .001). The majority of the amino acid susceptible to oxidative stress displayed lower levels in children with asthma (P < .05).

Conclusion

Childhood asthma is associated with significant decreases in various components of both enzymatic and nonenzymatic antioxidant defenses.

Section snippets

Patients with asthma

Patients with asthma have been detailed previously.15, 21, 22 Briefly, children with mild asthma age 6 to 16 years who were not receiving any controller medication and who had not had any symptoms of respiratory infection or asthma exacerbation within the previous 4 weeks were included in this study. Spirometric measurements, total IgE, and eosinophil counts were obtained. Skin testing was performed as detailed previously.15 From this cohort of white children with mild asthma, results are

Results

The study population consisted of 164 children with mild asthma and 173 healthy children. Characteristics of the study groups are summarized in Table I. As expected, asthma and atopy–related findings including IgE, skin prick tests, FEV1%, eosinophil counts and family history of allergic diseases were significantly different between the 2 groups (P < .001).

Discussion

The aim of our study was to evaluate comprehensively the various aspects of the antioxidant systems in children with asthma. Our results show that mild asthma in children is associated with significantly decreased levels of both enzymatic and nonenzymatic antioxidant pathways. Enzymatically, levels of both extracellular superoxide dismutase and glutathione peroxidase are decreased. Nonenyzmatically, in addition to the well known reduction in the levels of reduced glutathione, levels of the

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    Supported by Hacettepe University Scientific Research Fund grants #02 02 101 020, #01 402 01 002, and #01 402 01 004.

    Disclosure of potential conflict of interest: The authors have declared that they have no conflict of interest.

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