Effects of N-acetylcysteine plus deferoxamine in lipopolysaccharide-induced acute lung injury in the rat*

Abstract

Interventions that reduce the generation or the effects of reactive oxygen species exert controversial effects in animal models of lung injury, and these could be secondary to the pro-oxidant effects of antioxidants generally by their interaction with iron. We here describe the effects of N-acetylcysteine, deferoxamine, or both in the treatment of acute lung injury induced by intratracheal lipopolysaccharide injection. Prospective, randomized, controlled experiment. Animal basic science laboratory. Male Wistar rats, weighing 200-250 g. Rats exposed intratracheally to lipopolysaccharide were treated with N-acetylcysteine (20 mg/kg subcutaneously 3, 6, and 12 hrs after lipopolysaccharide instillation), deferoxamine (20 mg/kg subcutaneously 3 hrs after lipopolysaccharide instillation), N-acetylcysteine (20 mg/kg, 3, 6, and 12 hrs after lipopolysaccharide instillation) plus deferoxamine (20 mg/kg 3 hrs after lipopolysaccharide instillation), or vehicle. Acute lung injury was induced by intratracheal instillation of lipopolysaccharide in Wistar rats. The animals were randomly divided into five groups: group 1, control with instillation of isotonic saline; group 2, lipopolysaccharide treated with saline; group 3, lipopolysaccharide treated with N-acetylcysteine; group 4, lipopolysaccharide treated with deferoxamine; and group 5, lipopolysaccharide treated with N-acetylcysteine plus deferoxamine. Several times after lipopolysaccharide instillation, the rats were killed and a bronchoalveolar lavage was performed to determine thiobarbituric acid reactive species, protein carbonyls, superoxide dismutase and catalase activities, mitochondrial superoxide production (oxidative stress variables), the degree of the alveolar-capillary membrane compromise, and inflammatory infiltration. Samples from the lung were isolated and assayed for oxidative stress variables or histopathologic analyses. N-acetylcysteine plus deferoxamine decreased bronchoalveolar lavage fluid protein, inflammatory cells, oxidative damage variables, and proinflammatory cytokines. N-acetylcysteine plus deferoxamine treatment significantly attenuated lung oxidative damage, mitochondrial superoxide production, and histopathologic alterations after lipopolysaccharide instillation. Our data provide the first experimental demonstration that N-acetylcysteine plus deferoxamine decreases oxidative stress and mitochondrial dysfunction and limits inflammatory response and alveolar pathology induced by lipopolysaccharide in the rat.