Oxidative stress and alterations of paraoxonases in atopic dermatitis

Background: previous studies reported the involvement of reactive oxygen species (ROS) and lipid peroxidation in the pathogenesis of inflammatory skin diseases. The aim of our study was to investigate the relationship between oxidative stress and inflammation in children affected by atopic dermatitis (AD), a chronic relapsing inflammatory skin disease. Methods: levels of lipid hydroperoxides, total antioxidant capacity, and activities of the enzymes myeloperoxidase (MPO), PON1, and PON2/3 were investigated in 56 atopic pediatric patients, and compared with 48 sex-/age-matched healthy controls. Results: significantly higher levels of lipid hydroperoxides and lower values of total antioxidant potential were observed in the serum of AD children compared to that of the controls. Significant lower PON1 activities, and a significant increase in levels of MPO were observed in serum of patients, with a higher serum MPO level/PON1 paraoxonase activity ratio in patients compared to that in the controls. Significantly lower lactonase activity of PON enzymes was observed in polymorphonuclear cells isolated from AD patients. Statistically negative correlation was established between the activity of intracellular PON2/3 activity and ROS levels. Conclusions: our data confirmed that AD is associated with higher oxidative damage and a decrease in antioxidant defense. Moreover, alterations of extracellular and intracellular PON activity can promote lipoprotein dysfunction in AD patients