Pulmonary surfactant lipid-protein complex (SP-B and SP-C) (PS)

Pulmonary surfactant is a vital lipoprotein complex composed of approximately 90% lipids and 10% proteins, specifically Surfactant Proteins B (SP-B) and C (SP-C). It forms a surface-active monolayer at the alveolar air-liquid interface, which is essential for reducing surface tension and preventing alveolar collapse during expiration (StatPearls, 2023). SP-B is a small, hydrophobic protein required for the formation of lamellar bodies and the structural organization of the surfactant film, while SP-C enhances the rate of lipid adsorption and film stability (PubMed, 2001; UniProt, 2024). Clinical deficiency of this system, most notably in premature infants, results in Neonatal Respiratory Distress Syndrome (nRDS), characterized by high surface tension, lung collapse, and impaired gas exchange (NIH, 2022). Therapeutic intervention involves the administration of exogenous surfactants, such as Poractant alfa or Beractant, which utilize the biophysical properties of SP-B and SP-C to restore pulmonary mechanics (PubMed, 2015). These treatments are delivered intratracheally and are critical for improving survival and reducing the severity of lung injury in neonates and potentially in cases of acute respiratory distress.

Other names

Lung surfactantAlveolar surfactantPulmonary surfactant systemSP-B/SP-C lipid monolayerSurface active agent

Exogenous surfactant replaces deficient endogenous surfactant; the hydrophobic proteins SP-B and SP-C within the drug facilitate the rapid spreading, adsorption, and stabilization of phospholipids into a functional monolayer at the air-liquid interface, which lowers surface tension and prevents alveolar collapse (NIH, 2022; PubMed, 2001).