Pulmonary surfactant lipid layer

Pulmonary surfactant lipid layer refers to the essential, surface-active lipid–protein film that coats the alveolar epithelium in the lungs[1][2][4][7]. This layer is primarily composed of phospholipids (especially dipalmitoylphosphatidylcholine), neutral lipids (such as cholesterol), and specific surfactant-associated proteins (SP-A, SP-B, SP-C, SP-D), all synthesized and secreted by type II alveolar epithelial cells[2][4][7][8]. The lipid layer functions to reduce surface tension at the air–liquid interface of the alveoli, thereby preventing alveolar collapse during exhalation, supporting lung compliance, and facilitating normal respiratory mechanics[2][4][7]. It also plays vital roles in lung defense, forming a barrier to pathogens and supporting immune functions, in part via surfactant proteins[3][5][7]. However, "pulmonary surfactant lipid layer" is not a single molecular entity, drug target, receptor, or enzyme but rather a complex supramolecular assembly critical to lung structure and function. Consequently, it is not considered a canonical drug target, though it is the site of action for exogenously administered surfactant therapies[4][5][7].

Other names

Pulmonary surfactant monolayeralveolar surfactant lipid layerlung surfactant lipid film

Supplementation or replacement of endogenous surfactant to restore surface tension regulation and improve gas exchange