Lipid peroxidation as determined by plasma isoprostanes is related to disease severity in mild asthma

Oxidlative stress is believed to play an important role in the pathophysiology of asthma. Recently discovered F2-isoprostanes, of which 8-iso-PGF2alpha is the most well-known isomer, have emerged as the most reliable marker of in vivo oxidative stress. The aim of this study was to examine 8-iso-PGF2alpha as a biomarker of oxidative stress in mild asthma in relation to endogenous and dietary antioxidant protection. Total (free and esterified) plasma 8-iso-PGF2alpha, plasma dietary antioxidants (vitamins E and C, Beta-carotene, Zn, and Se), and erythrocyte antioxidant enzyme activities (glutathione peroxidase and superoxide dismutase) were measured in 15 mild asthmatics and 15 age-and sex-matched controls. Total plasma 8-iso-PGF2alpha levels [median (quartile 1 - quartile 3)] were significantly increased in the asthmatics [213 pg/mL (122-455) vs. 139 pg/mL (109-174), P= 0.042]. The 8-iso PGF2alpha levels were found to be associated with clinical asthma severity (P = 0.044) and inhaled corticosteroid use (P = 0.027) in asthmatics. No differences were observed in the plasma dietary antioxidant vitamins. The asthmatics had significantly lower plasma levels of Zn (P = 0.027) and Se (P = 0.006). Plasma Se correlated negatively with 8-iso-PGF2alpha (r = -0.725, P= 0.002). No differences between the groups were observed for glutathione peroxidase or superoxide dismutase, however, superoxide dismutase activity was negatively associated with asthma severity (P = 0.042). In conclusion, oxidative stress is increased in mildly asthmatics, as reflected by increased plasma levels of 8-iso-PGF2alpha and a deficiency in plasma Zn and Se. The isoprostane 8-iso-PGF2alpha may provide a useful tool in intervention studies aimed at improving clinical status in asthma.