Administering recombinant interleukin-1 beta (IL-1 beta) intratracheally caused lung neutrophil accumulation and lung injury in hamsters. The percentage of leukocytes that were neutrophils increased progressively in lavages from lungs of hamsters given 25, 50, or 100 ng IL-1 beta intratracheally 2 h before. Lung injury, reflected by increased lung lavage protein concentrations and lung lavage hemoglobin concentrations, increased 2 h after administering 100 ng IL-1 beta. Lung injury, reflected by lung wet weight/body weight ratios, followed similar patterns, with significant increases occurring 2 h after insufflating 50 or 100 ng IL-1. Our results indicate that increased concentrations of IL-1 beta in lung airways can cause neutrophil recruitment and lung injury in hamsters. This mechanism may contribute to the development of lung neutrophil accumulation and lung injury that characterizes ARDS patients who have increased airway levels of IL-1 beta.

We found that intratracheal administration of recombinant interleukin-1 alpha (IL-1) into rats rapidly (< 5 h) increased neutrophils in lung lavages and caused an acute edematous lung injury which was reflected by lung albumin accumulation (lung leak) and histological abnormalities (perivascular cuffing). These IL-1-dependent processes were inhibited by prior administration of recombinant IL-1 receptor antagonist and did not occur following administration of heated IL-1. Several lines of evidence suggested that neutrophil-derived oxygen metabolites contributed to lung leak. First, lung leak did not occur in rats rendered neutropenic by vinblastine treatment 4 days before IL-1 administration but did occur in neutrophil-replete rats given vinblastine 1 day before IL-1 administration and control rats given IL-1. Second, treatment with a hydroxyl radical scavenger, dimethyl sulfoxide (DMSO) or a superoxide anion scavenger, manganese superoxide dismutase, decreased lung leak, lung lavage neutrophils, and histological abnormalities in rats given IL-1 intratracheally. Third, intratracheal IL-1 administration increased lung oxidized glutathione (GSSG) levels and expired H2O2 concentrations, and these two indices of oxidative stress were decreased by dimethyl sulfoxide or manganese superoxide dismutase treatment. We conclude that intratracheal administration of IL-1 increases neutrophils in the lung and causes a neutrophil and oxygen metabolite-dependent acute edematous lung injury.

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