Surfactant protein-D and surfactant inhibit endotoxin-induced pulmonary inflammation

Acute lung injury is a common cause of morbidity and mortality following pulmonary or systemic infections. Surfactant protein-D is a member of the collectin family of proteins, which play important roles in innate host defense of the lung. In this study, the effect of exogenous recombinant human SP-D (rhSP-D) on protection of the adult mouse lung from lipopolysaccharide (LPS)-induced and lipoteichoic acid (LTA)-induced injury was assessed.

The effect of rhSP-D on LPS-induced and LTA-induced lung inflammation and injury was assessed with and without exogenous pulmonary surfactant in Sftpd+/+ and Sftpd-/- mice. A total of 204 mice (6 mice per group) were used for the present study.

Sftpd-/- mice were more susceptible to intratracheal LPS than were Sftpd+/+ mice. rhSP-D decreased neutrophilic infiltrates induced by LPS and LTA in the lungs of both Sftpd+/+ and Sftpd-/- mice. The addition of exogenous pulmonary surfactant to rhSP-D further decreased LPS-induced and LTA-induced pulmonary inflammation in Sftpd-/- and Sftpd+/+ mice.

Intratracheal rhSP-D inhibited inflammation induced by intratracheal LPS and LTA instillation in the lung. The antiinflammatory effects of rhSP-D were enhanced by the addition of pulmonary surfactant, providing a potential therapy for the treatment of lung inflammation.