Changes in Pulmonary Interleukin-6 and Pulmonary Pathology in Neonatal Mice After Exposure to Hyperoxia and Ascorbate Treatment

ABSTRACT

PURPOSE: Levels of proinflammatory cytokines such as IL-1, IL-6 and TNF-alpha have been shown to be increased in the lung of adult mice after exposure to hyperoxia. Ascorbate, a non-enzymatic antioxidant, might have a protective effect against oxygen-induced lung injury. We examined effects of hyperoxia and ascorbate treatment on pulmonary IL-6 levels and pathology in the lungs of newborn mice. METHODS: Neonatal mice were exposed to hyperoxia (95% O2) or room air (control) for 24 h or 48 h. Other groups, exposed to hyperoxia for up to 48 h, were injected intraperitoneally preventive doses (0.1 mg/10 g mouse weight) or therapeutic doses (1 mg/10 g mouse weight) of ascorbate or distilled water (placebo control) twice, immediately before and at 24 h of exposure to hyperoxia. IL-6 concentrations in the supernatant of minced lungs were measured by ELISA. RESULTS: There were no pathologic changes in the lungs except mild emphysema and alveolar hemorrhage. The median pulmonary IL-6 concentration was significantly higher in mice exposed to hyperoxia for 24 h (P<0.05) and for 48 h (P<0.001) than room air controls. There was no difference in pulmonary IL-6 concentration between hyperoxia-exposed (48 h) mice treated with either preventive or therapeutic doses of ascorbate and placebo controls. CONCLUSION: Neonatal mice exposed to hyperoxia for 24 h and 48 h showed higher pulmonary IL-6 concentrations than room air controls. Preventive or therapeutic doses of ascorbate had no effect on pulmonary IL-6 concentrations nor pulmonary pathology of neonatal mice exposed to hyperoxia for 48 h.