Altered airway surfactant phospholipid composition and reduced lung function in asthma

Area of Science:

• Pulmonary physiology
• Respiratory medicine
• Biochemistry

Background:

• Pulmonary surfactant is crucial for lung function, maintaining alveolar stability.
• Asthma is a chronic respiratory disease characterized by airway inflammation and reversible airflow obstruction.
• Surfactant dysfunction is hypothesized to play a role in asthma pathogenesis.

Purpose of the Study:

• To analyze phospholipid and protein composition and function of pulmonary surfactant in bronchoalveolar lavage fluid (BALF) and induced sputum from stable asthma patients and healthy controls.
• To investigate the correlation between surfactant composition, function, and lung function parameters in asthma.

Main Methods:

• Analysis of phospholipid and protein composition in BALF and sputum from 36 asthma patients (mild, moderate, severe) and 12 healthy controls.
• Assessment of surfactant function using a capillary surfactometer.
• Correlation analysis between surfactant composition, function, and lung function (forced expiratory volume in 1 second).

Main Results:

• The proportion of dipalmitoyl phosphatidylcholine (16:0/16:0PC), a key surfactant phospholipid, was decreased in sputum of asthmatic subjects compared to controls (P < 0.05).
• No significant alteration in 16:0/16:0PC was observed in BALF of asthmatic subjects.
• BALF 16:0/16:0PC correlated with surfactant function, while sputum 16:0/16:0PC correlated with lung function (FEV1). Surfactant protein A and total protein levels were unchanged.

Conclusions:

• Stable asthma is associated with altered phospholipid composition and function of airway (sputum) surfactant, but not alveolar (BALF) surfactant.
• This airway surfactant dysfunction may contribute to airway closure in asthma and increase susceptibility to further inhibition.
• Therapeutic administration of appropriate surfactant may offer clinical benefits for asthma management.