Pulmonary surfactant protein C (SP-C)

Pulmonary surfactant protein C (SP-C) is a highly hydrophobic, 35-residue proteolipid essential for normal lung function and homeostasis, secreted by type II alveolar epithelial cells (AE2C) in the lung. It is a critical component of pulmonary surfactant—a lipid-protein complex that maintains alveolar stability by reducing surface tension at the air-liquid interface, thus preventing alveolar collapse during breathing[1][3][4][7][5]. SP-C promotes the rapid adsorption and spreading of surfactant phospholipids, assists in the transfer of lipids within surfactant layers, and aids in maintaining the structural integrity of the multilayered surfactant system. Structurally, SP-C consists of a transmembrane α-helical segment rich in valine, with two thioester-linked palmitoyl groups at the N-terminus, allowing strong membrane association[2][5][6]. Deficiency or dysfunction of SP-C, often due to mutations in its encoding gene SFTPC, leads to severe chronic lung diseases including interstitial lung disease, pulmonary fibrosis, and pulmonary alveolar proteinosis[1][4][7]. Recombinant SP-C or its analogs are used therapeutically in some artificial surfactant formulations for neonatal respiratory distress syndrome, though no small-molecule drugs directly target this protein[7]. Notable safety and therapeutic challenges include the protein's tendency to misfold and aggregate, especially due to disease-linked mutations, potentially causing toxic effects in pulmonary tissue[1][7].

Other names

Surfactant protein CSP-CSFTPC (gene symbol)SFTP2 (previous symbol)PSPC

Replacement/supplementation therapy for surfactant deficiency (for recombinant forms)