Surfactant proteins SP-A and SP-D in human health and disease.
Surfactant proteins A (SP-A) and D (SP-D) are lung surfactant-associated hydrophilic proteins that have been implicated in surfactant homeostasis and pulmonary innate immunity. They are collagen-containing C-type (calcium-dependent) lectins, called collectins, and are structurally similar to mannose-binding protein of the lectin pathway of the complement system. Being carbohydrate pattern-recognition molecules, they recognize a broad spectrum of pathogens and allergens via the lectin domain, with subsequent activation of immune cells via the collagen region, thus offering protection against infection and allergenic challenge. SP-A and SP-D have been shown to be involved in viral neutralization, clearance of bacteria, fungi, and apoptotic and necrotic cells, down-regulation of allergic reaction, and resolution of inflammation. Studies on single-nucleotide polymorphism, protein levels in broncho-alveolar lavage, and gene knock-out mice have clearly indicated an association between SP-A and SP-D and a range of pulmonary diseases. In addition, recent studies using murine models of allergy and infection have raised the possibility that the recombinant forms of SP-A and SP-D may have therapeutic potential in controlling pulmonary infection, inflammation, and allergies in humans.
Kishore
Uday
U
Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Headington, Oxford OX3 9DS, UK. ukishore@hotmail.com
Bernal
Andrés López
AL
Kamran
Mohammed F
MF
Saxena
Shweta
S
Singh
Mamta
M
Sarma
P Usha
PU
Madan
Taruna
T
Chakraborty
Trinad
T
D000818:Animals; D001249:Asthma / Q000209:etiology; D015415:Biomarkers; D001997:Bronchopulmonary Dysplasia / Q000209:etiology; D005260:Female; D005315:Fetal Diseases / Q000517:prevention & control; D006801:Humans; D006967:Hypersensitivity / Q000209:etiology; D007231:Infant, Newborn; D008168:Lung / Q000276:immunology / Q000382:microbiology; D051379:Mice; D011247:Pregnancy; D037662:Pulmonary Surfactant-Associated Protein A / Q000032:analysis / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D037663:Pulmonary Surfactant-Associated Protein D / Q000032:analysis / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D012128:Respiratory Distress Syndrome / Q000209:etiology; D014397:Tuberculosis, Pulmonary / Q000209:etiology
D015415:Biomarkers; D037662:Pulmonary Surfactant-Associated Protein A; D037663:Pulmonary Surfactant-Associated Protein D