Phagocyte-induced lipid peroxidation of lung surfactant

Surfactant therapy is given routinely to premature newborns with respirator y failure. However, alterations in surfactants have been shown to be a sign ificant factor in some forms of respiratory failure in newborns in animal m odels of lung injury. To investigate whether antioxidant supplementation mi ght help to protect exogenous surfactant from damage by oxygen free radical s, we examined the influence of vitamin E in combination with surfactant on superoxide production as estimated by the nitroblue tetrazolium reduction test, and measured surfactant peroxidation with a new colorimetric method w ith or without addition of superoxide dismutase (SOD) or vitamin E. Our results showed that surfactant interacts with free radicals; surfactant reduced superoxide production by neutrophils and was peroxidized when incu bated with resting and with stimulated cells. Vitamin E supplementation dec reased superoxide radical production and in a dose-dependent manner decreas ed surfactant peroxidation. The decrease in lipid peroxidation by SOD was n ot significant. These findings suggest that phagocytes induce lipid peroxidation of lung su rfactant, a reaction that might be prevented by antioxidants. (C) 1999 Wile y-Liss, Inc.