Changes In Exhaled Breath Particles Lipid Composition Following Experimental Endotoxin Challenge

Introduction: Alterations of surfactant phospholipid composition in the epithelial lining fluid play a role in acute and chronic lung diseases. The investigation of phospholipid composition and turnover currently requires the invasive sampling by bronchoalveolar lavage (BAL). Exhaled breath particles (PEx), which are formed when collapsed small airway re-open during inhalation, can be collected non-invasively. Here we assessed the changes in PEx lipid composition compared to BAL and induced sputum (ISP) following experimental endotoxin (LPS) challenge. Methods: A segmental and a whole lung inhalation LPS challenge was performed in 10 healthy volunteers separated by 4 weeks. Besides Pex, BAL fluid was sampled from the challenged segment and ISP following inhalation challenge. After extraction samples were analyzed by LC-MS/MS. Lipids were quantified relative to the major surfactant phospholipid dipalmitoyl-phosphatidylcholine DPPC. Results: A common set of 15 lipids were analyzed in BAL, PEx and ISP. Lipid composition was very similar between sample types and typical for lung surfactant. The most pronounced changes were observed in BAL fluid from the LPS challenged segment compared to the saline challenged segment (10/14 lipids relative to DPPC p<0.05). Four of these were also significantly changed in ISP (p≤0.05). Despite qualitatively comparable changes in PEx compared to BAL and ISP, these seldom reached statistical significance. Conclusion: BAL data demonstrates that LPS induces changes in lipid composition in the peripheral lung. The weaker effects in PEx could be due to the fact that PEx are sampled from the whole lung, while the LPS effect was restricted to one lobe of the lung.