Karger Publishers, Neonatology, 4(91), p. 233-240, 2006
DOI: 10.1159/000098170
Full text: Unavailable
<i>Background:</i> Exogenous surfactant has been accepted worldwide as a therapy of RDS in premature and term infants. Exogenous surfactant is usually derived from lung extracts containing phospholipids and the surfactant proteins SP-B and SP-C. Synthetic peptides of SP-B and SP-C are being tested with the aim to develop a completely synthetic surfactant preparation. Nevertheless, the effects of these peptides on the endogenous surfactant metabolism remain unknown. <i>Objectives:</i> The effect of synthetic SP-B peptides on uptake of surfactant-like liposomes was investigated in alveolar cells. Native SP-B and seven SP-B peptides were included: monomeric and dimeric SP-B<sub>1–25</sub> (Cys-11 → Ala-11), SP-B<sub>63–78</sub>and Ala-SP-B<sub>63–78</sub> (Cys-71 → Ala-71;Cys-77 → Ala-77)and their serine mutants. <i>Methods:</i> In vitro<i>,</i> alveolar macrophages (AM) and alveolar type II cells (ATII) were incubated with liposomes containing SP-B or one of its peptides. In vivo<i>, </i>rats received intratracheally various SP-B peptides (SP-B/lipid ratio 1:33 w/w) incorporated in fluorescent surfactant-like liposomes. One hour after instillation, AM and ATII were isolated and cell-associated fluorescence was determined using flow cytometry. Confocal laser microscopy was performed to ensure internalization of the liposomes. <i>Results:</i> In vitro uptake by AM or ATII was not influenced by the SP-B peptides. In vivo<i>, </i>SP-B<sub>1–25</sub> and Ser-SP-B<sub>1–25</sub> increased the uptake by AM whereas dSP-B<sub>1–25</sub> decreased the uptake. Neither SP-B<sub>1–25</sub> nor dSP-B<sub>1–25 </sub>affected total uptake by ATII. The overall uptake by SP-B<sub>63–78</sub> variants was not changed. <i>Conclusions:</i> Surface-active synthetic SP-B peptides do not interfere with the normaluptake of surfactant by ATII.