In vitro modulation of induced neutrophil activation by different surfactant preparations

Endotracheal surfactant administration has gained an important role in the treatment of respiratory failure. Polymorphonuclear neutrophil granulocyte (PMN) activation mediated by chemoattractants, such as interleukin-8 (IL-8), neutrophil-activating peptide-2 (NAP-2) and formylated bacterial oligopeptides, has been found to be involved in the pathophysiology of acute respiratory failure. We investigated potential modulating effects of commercial surfactant preparations (Exosurf, Alveofact, Curosurf and Survanta) on spontaneous and chemoattractant-induced PMN function. Isolated cytochalasin B (CytB)-treated PMNs from healthy adults were incubated with increasing concentrations of surfactant. The response of the cells was measured in terms of elastase release from the lysosomes within 30 min. The PMNs showed no direct activation by any of the surfactants tested. However, when cells were stimulated with suboptimal dosages of chemokines, such as IL-8 (2 nM) or NAP-2 (100 nM), or formyl-methionyl-leucyl-phenylalanine (fMLP) (50 nM), and co-incubated with increasing concentrations of surfactant (0.05-8 mg.mL-1) the release of elastase was markedly modulated depending on the surfactant preparation used. Whilst Exosurf and Alveofact showed only modest effects on the elastase release induced by all three mediators, Curosurf and Survanta markedly inhibited the cellular response in a dose-dependent manner. At concentrations above 1 mg.mL-1, Curosurf and Survanta decreased the IL-8-, NAP-2- and fMLP-induced elastase release by 83, 67 and 90%, and by 82, 75 and 80%, respectively. In conclusion, exogenous surfactant may modulate the inflammatory response of the airways by affecting the chemoattractant-induced polymorphonuclear neutrophil activation. Surfactant preparations with inhibiting properties on neutrophil activation may participate in the prevention of neutrophil-induced lung damage.