Mechanisms of surfactant maturation in development and diseases

Pulmonary surfactant is a lipoproteinaceous material secreted exclusively by alveolar type 2 cells into the alveolar space. It is primarily responsible for reducing the work of breathing by reducing surface tension at the air-liquid interface, though has important additional roles in the innate immune response. Packaging of pulmonary surfactant is complex, involving specialised trafficking and post translational modification of both lipid and protein components to facilitate the formation of lamellar bodies in which surfactant is packaged before exocytosis. Aberrancies of pulmonary surfactant maturation, secretion, function and recycling can have profound impacts on alveolar epithelial dysfunction and respiratory function. Manifestations are diverse, ranging from fatal neonatal respiratory failure to adult-onset interstitial lung disease. Here, we consider aspects of pulmonary surfactant genesis, function and clearance in health and disease, also highlighting current and future therapies for surfactant-associated disease and the challenges of progressing research in the field.