Pulmonary surfactant-associated protein B (SP-B) (SP-B)

Pulmonary surfactant-associated protein B (SP-B) is a small, highly hydrophobic protein that is essential for life and normal lung function [1, 3]. It is synthesized by alveolar type II cells and is a critical component of the pulmonary surfactant system, which lines the alveoli to reduce surface tension [1, 10]. SP-B facilitates the rapid formation of a phospholipid monolayer at the air-liquid interface, preventing alveolar collapse during expiration [1, 12]. It belongs to the saposin-like protein family and functions by organizing lipids into complex structures like tubular myelin [2, 11]. Genetic mutations in the SFTPB gene lead to fatal neonatal respiratory distress, underscoring its indispensable role in breathing [1, 8]. In clinical practice, SP-B is a primary target for surfactant replacement therapy in premature infants with respiratory distress syndrome [6, 13]. Therapeutic agents include natural porcine or bovine lung extracts and synthetic peptides that mimic SP-B's helical domains [12, 13]. Beyond its biophysical role, SP-B is also involved in modulating inflammatory responses and serves as a potential biomarker for various lung diseases, including COPD and lung cancer [15, 16, 20]. Drugs interacting with SP-B aim to restore lung compliance and improve oxygenation in patients with surfactant deficiency or inactivation [7, 19].

Other names

SFTPBPSP-BSFTB3SFTP3SMDP118 kDa pulmonary-surfactant protein6 kDa proteinPulmonary surfactant-associated proteolipid SPL(Phe)

Surfactant replacement therapy involves the administration of SP-B-containing preparations to restore the surface-active properties of the alveolar lining, thereby reducing surface tension, preventing alveolar collapse, and improving gas exchange [12, 13, 19].