EARLY DIVERGENT LUNG ANTIOXIDANT ENZYME EXPRESSION IN RESPONSE TO LIPOPOLYSACCHARIDE

Lipopolysaccharide (LPS), a component of the cell wall of Gram-negativ e bacteria, interacts with eukaryotic cells, causing changes in gene e xpression and a rapid increase in the formation of superoxide and H2O2 We now report that, within 6 h of treating rats with LPS, there was a divergent response in the lung of manganese superoxide dismutase (Mn- SOD) and catalase expression without a change in expression of copper- zinc superoxide dismutase or glutathione peroxidase. The activity and mRNA concentration of Mn-SOD increased during the time catalase mRNA c oncentration and activity decreased. These divergent changes and activ ation of nuclear factor-kappa B (NF-kappa B) were preceded by a fall, 1 h after LPS treatment, in the RNA binding activity of two redox-sens itive proteins: Mn-SOD RNA binding protein and catalase RNA binding pr otein. The rapid onset of these changes, the bacteriostatic properties of H2O2, and the signaling function of NF-kappa B suggest that the di vergent expression of Mn-SOD and catalase is a coordinated component o f the acute phase reaction to bacterial invasion.