Surfactant proteins A and D: disease markers

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.