Reduced platelet glutathione peroxidase activity and serum selenium concentration in atopic asthmatic patients

Background Asthmatic inflammation results in increased oxygen free radical generation and assessment of the activity of the selenitim (Se) dependent anti-oxidant enzyme, glutathione peroxidase (GSH-Px) in asthma may therefore be important. Objective To test the hypothesis that reduced GSH-Px activity and Se intake contribute to asthmatic infiammation, platelet and whole blood GSH-Px activities and serum and whole blood Se concentrations were measured and compared in atopic and non-atopic asthmatic patients and non-asthmatic control subjects. Methods GSH-Px activities of whole blood and isolated platelets were assessed in 41 asthmatic patients (33 atopic) and 41 age- and sex-matched non-asthmatic sttbjects (15 atopic) by spectrophotometric assay based oti the oxidation of NADPH. Se concentrations were determined by semi-automated fluorimetric assay. Results Mean (± sd) platelet GSH-Px activity was lower in asthmatic (89.5 ± 45.7 μmol NADPH oxidized min^?1 g^?1 of protein) than in non-asthmatic subjects (109,9 ± 41.9; P= 0.038) and in atopic (89.7 ± 45.1, n = 48) compared with non-atopie subiects (113.7 ± 40.9, n= 34: P= 0.016). Mean whole blood GSH-Px activity was also lower in atopic (12.2 ± 5.2 μmol NADPH oxidized min^?1 g^?1 of Hb) than in non-atopic subjects (14.5 ± 4.2; P= 0.038). In non-asthmatic subjects, the mean whole blood GSH-Px activity was lower in men (9.9 ± 3.5) than in women (14.5 ± 3.7; P = 0.0004) and was positively correlated with age (r= 0.51; P = 0.0006). Mean serum Se was lower in asthmatic (1.07 ± 0.12 μmol/L) than in non-asthmatic subjects (1.16 ± 0.31; P = 0.036), Using multiple linear regression, asthma was an independent predictor of decreased platelet GSH-Px after gender, age and serum Se were taken into account (P = 0.048) while atopy was a significant predictor of low whole blood GSH-Px independent of asthma, gender, age and whole blood Se (P = 0.033). Conclusions In addition to Se status, atopy, gender and uge all appear to influence GSH-Px activity, although the relative importance of these factors may difler in asthmatic and non-asthmatic populations. It seems likely that the reduced activity of this enzyme in platelets und hiood may reflect mechanisms associated with the pathogenesis and severity of asthma.