Influence of surfactant on pulmonary inflammatory response and release of elastase in experimental neonatal group B streptococcal pneumonia

Purpose: We analyzed the influence of surfactant on inflammatory response, bacterial proliferation and tissue levels of free elastase, a key neutrophil enzyme, in experimental neonatal group B-streptococcal pneumonia. Method: Near-term tracheotomized rabbit fetuses were infected intratracheally with streptococci and ventilated for 5 h. Following the infection the animals received either surfactant (Curosurf 200 mg/kg) or saline (2.5 ml/kg). Controls (n = 11) received only saline. One group of animals (n = 8) was investigated immediately following the injection of bacteria. Results: Surfactant-treated animals demonstrated mitigation of bacterial growth and less marked inflammatory changes on light microscopic examination when compared with infected littermate controls receiving saline. In addition, significantly lower tissue levels of elastase could be demonstrated in the surfactant-treated group (mean +/- SEM: 4.22 +/- 0.95 vs 8.02 +/- 1.28 mu g/g lung; p < 0.05). Animals treated with saline alone and animals investigated immediately following infection had significantly (p < 0.05) lower tissue levels of free elastase in lung homogenate (2.97 +/- 0.57 and 2.01 +/- 0.45 mu g/g lung, respectively). Conclusions: Based on our results we speculate that surfactant plays an important role in the regulation of inflammatory response in neonatal infectious lung disease.