Related Experiment Videos
Surfactant proteins A and D: disease markers
Y Kuroki1, H Takahashi, H Chiba
1Department of Biochemistry, Sapporo Medical University School of Medicine, South-1 West-17, Chuo-ku, Sapporo 060-8556, Japan. kurokiy@sapmed.ac.jp
Insights
Surfactant proteins SP-A and SP-D are key biomarkers for various lung diseases, aiding in diagnosis and prognosis. Their levels in bodily fluids like BAL fluid, sputum, and serum offer insights into lung maturity, disease activity, and cancer detection.
Area of Science:
- Pulmonary Medicine
- Biomarker Discovery
- Respiratory Physiology
Background:
- Surfactant proteins SP-A and SP-D are lung-specific collectins.
- Their expression patterns are altered in various pulmonary conditions.
Purpose of the Study:
- To explore the diagnostic and prognostic value of SP-A and SP-D in lung diseases.
- To assess their utility in differentiating various pulmonary conditions and cancers.
Main Methods:
- Measurement of SP-A and SP-D concentrations in amniotic fluid, tracheal aspirates, bronchoalveolar lavage (BAL) fluid, sputum, and serum.
- Analysis of SP-A/phospholipid ratio in specific lung diseases.
Main Results:
- SP-A and SP-D indicate lung maturity in infants with respiratory distress syndrome (RDS).
- Decreased SP-A in BAL fluid is linked to acute respiratory distress syndrome (ARDS).
- Elevated SP-A and SP-D in BAL fluid and sputum are diagnostic for pulmonary alveolar proteinosis (PAP).
- Lower SP-A/SP-D in BAL fluid for idiopathic pulmonary fibrosis (IPF) and interstitial pneumonia with collagen vascular diseases (IPCD), with SP-A/phospholipid ratio predicting survival.
- Increased serum SP-A/SP-D in PAP, IPF, IPCD, and ARDS, indicating disease activity.
- SP-A serves as a marker for lung adenocarcinomas, aiding in cancer differentiation and metastasis detection.
Conclusions:
- SP-A and SP-D are valuable biomarkers across a spectrum of lung diseases, from neonatal respiratory distress to adult interstitial lung diseases and cancers.
- Monitoring these proteins in various clinical samples can aid in diagnosis, prognosis, and disease activity assessment.
Abstract:
The abundant and restricted expression of surfactant proteins SP-A and SP-D within the lung makes these collectins specific markers for lung diseases. The measurement of SP-A and SP-D in amniotic fluids and tracheal aspirates reflects lung maturity and the production level of the lung surfactant in infants with respiratory distress syndrome (RDS). The SP-A concentrations in bronchoalveolar lavage (BAL) fluids are significantly decreased in patients with acute respiratory distress syndrome (ARDS) and also in patients at risk to develop ARDS. The prominent increase of these proteins in BAL fluids and sputum is diagnostic for pulmonary alveolar proteinosis (PAP). The concentrations of SP-A and SP-D in BAL fluids from patients with idiopathic pulmonary fibrosis (IPF) and interstitial pneumonia with collagen vascular diseases (IPCD) are rather lower than those in healthy controls and the SP-A/phospholipid ratio may be a useful marker of survival prediction. SP-A and SP-D appear in the circulation in specific lung diseases. Their serum concentrations significantly increase in patients with PAP, IPF and IPCD. The successive monitoring of serum levels of SP-A and SP-D may predict the disease activity. The serum SP-A levels increase in patients with ARDS. SP-A is also a marker for lung adenocarcinomas and can be used to differentiate lung adenocarcinomas from other types and metastatic cancers from other origins, and to detect metastasis of lung adenocarcinomas.