Surfactant protein A--from genes to human lung diseases.
Surfactant associated protein-A (SP-A) is the most abundant pulmonary surfactant protein and belongs to the family of innate host defense proteins termed collectins. Besides pulmonary host defense, SP-A is also involved in the formation of pulmonary surfactant, as it is essential for the structure of tubular myelin. The human SP-A gene locus includes two functional genes, SFTPA1 and SFTPA2 which are expressed independently, and a pseudo gene. The largest amount of SP-A1 proteins assemble to larger molecular complexes, whereas SP-A2 forms mainly dimers and trimers. SP-A polymorphisms play a role in respiratory distress syndrome, allergic bronchopulmonary aspergillosis and idiopathic pulmonary fibrosis. The levels of SP-A are decreased in the lungs of patients with cystic fibrosis, respiratory distress syndrome and further chronic lung diseases. Future areas for clinical research include disease specific SP-A expression pattern and their functional consequences, the differential roles of SP-A1 and SP-A2 in human lung diseases, and therapeutical approaches to correct altered SP-A levels.
Heinrich
S
S
Pediatric Pneumology, Hauner Children's Hospital, Ludwig-Maximilians-University, Munich, Germany.
Hartl
D
D
Griese
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M
D006801:Humans; D007231:Infant, Newborn; D008171:Lung Diseases / Q000209:etiology* / Q000235:genetics; D037662:Pulmonary Surfactant-Associated Protein A / Q000235:genetics* / Q000502:physiology
D037662:Pulmonary Surfactant-Associated Protein A; C445842:SFTPA1 protein, human; C445843:SFTPA2 protein, human