Alterations of surfactant phospholipids in lungs with chronic recurrent respiratory chlamydial infection

This study aimed to identify alterations in the composition of surfactant phospholipids (PLP) with respect to chronic respiratory chlamydial infection. Broncho-alveolar lavage fluid (BALF) was sampled from 13 calves with naturally acquired chronic, but clinically latent, chlamydial infection (C. pecorum and/or C. abortus). Calves without chlamydial infections of the same age and kept under identical conditions served as controls (n = 12). Prior to BAL, exhaled breath condensate (EBC) was collected in each animal. In both BALF and EBC, phospholipids were measured (triplequad tandem mass spectrometer). Phosphatidylcholine (PC), being the main phospholipid in pulmonary surfactant and measurable in both EBC and in BALF samples, was significantly reduced in animals with chlamydial infections. In addition, concentrations of lysophosphatidylcholin, phosphatidylethanolamine (PE), and phosphatidylinositol (PI) were significantly reduced in BALF (not measurable in EBC). Altogether, total concentration of phospholipids was significantly lower but ratios between PC/PI and PG/PE (PG: phosphatidylglycerol) were significantly higher in calves with chlamydial infection compared to controls. In conclusion, chronic respiratory infections with chlamydiae were associated with significant alterations in the phospholipid composition of the epithelial lining fluid of the lung. Since surfactant is involved in both lung compliance as well as alveolar clearance, results of this study indicate chlamydia-associated deterioration of pulmonary mechanics and depressed alveolar defense mechanisms despite the absence of clinical signs or pulmonary symptoms.