The therapeutic effects of surfactants on acute lung injury derive not only from their recruiting action on collapsed alveoli but also from their anti-inflammatory action in the alveolar space. This study evaluated the anti-inflammatory action of a surfactant in an acute lung injury model of rats by measuring the WBC count, IL-1β and IL-6 level of bronchoalveolar lavage(BAL) fluid. In addition, neutrophils were recollected from the BAL fluid and the NF-γ B activity of the neutrophilic nuclear protein was evaluated.

Male Sprague-Dawley rats weighing approximately 300 gram were divided into 3 groups, which consisted of 6 rats respectively. In the control group, normal saline(3ml/kg) was instilled into the trachea twice with 30 minute interval. In two other groups, acute lung injury was induced by the intra-tracheal instillation of LPS(5mg/kg). Thirty minutes later, either a surfactant(ST group; 30mg/kg) or normal saline(NT group: 3ml/kg) was instilled via the trachea. Twenty-four hours after the LPS instillation, the BAL fluid was retrieved to measure the WBC count and cytokine(IL-1β and IL-6) levels. The neutrophils were isolated from the BAL fluid and the nuclear protein was extracted to evaluate the NF-γ Bactivity using a eletrophoretic mobility shift assay(EMSA).

The WBC count of the BAL fluid of the ST group(3,221±1,914 × 10³/µl) was higher than that of the control group(356±275 × 10³/µl)(p<0.05) and lower than that of the NT group(5,561±1,757 × 10³/µl)(p<0.05)). The BAL fluid level of IL-1β from the NT group(2,064±1,082pg/ml) was higher than those of the ST group(360±234pg/ml)(p<0.05) and the control group(0pg/ml)(p<0.05). The BAL fluid concentration of IL-6 from the NT group(3,621±567pg/ml) was also higher than those of the ST group(1,754±1,340pg/ml)(p<0.05) and control group(49±62pg/ml)(p<0.05). The NF-γ B activity of the neutrophilic nuclear protein in the ST group and NT group was similar.

The surfactant attenuates the alveolar inflammation in the acute lung injury of rats model. However, its anti-inflammatory action does no't appear to be mediated by the inhibition of NF-γ B activity.