Surfactant protein A (SP-A) (SP-A)

Surfactant protein A (SP-A) is the most abundant protein component of pulmonary surfactant, a lipoprotein complex essential for maintaining alveolar stability and lung host defense [2, 12, 19]. As a member of the collectin family of C-type lectins, SP-A functions both as a structural regulator of surfactant metabolism and as a soluble pattern recognition receptor [6, 16]. It facilitates the formation of tubular myelin and regulates the uptake and recycling of phospholipids by type II alveolar epithelial cells, thereby preventing alveolar collapse [3, 10, 13]. In the immune system, SP-A opsonizes a wide range of pathogens, including bacteria and viruses, to enhance their clearance by alveolar macrophages while modulating the inflammatory response to prevent tissue damage [5, 7, 12]. Dysregulation or genetic deficiency of SP-A is implicated in several respiratory diseases, such as neonatal respiratory distress syndrome, idiopathic pulmonary fibrosis, and susceptibility to pneumonia [1, 15, 17]. Although many current surfactant replacement therapies exclude SP-A to minimize immunogenicity, the development of recombinant human SP-A aims to restore its critical immunomodulatory and antimicrobial functions in end-stage or acute lung conditions [11, 13].

Other names

Pulmonary surfactant-associated protein APSP-ASFTPAPSAPCollectin-4Surfactant protein A1Surfactant protein A2

Surfactant replacement and modulation of host defense through opsonization and regulation of alveolar macrophage activity.