Interfacial phospholipids inhibit ozone-reactive absorption-mediated cytotoxicity in vitro

Area of Science:

• Pulmonary toxicology
• Biophysics
• Cell biology

Background:

• Inhaled ozone (O(3)) causes lung injury through complex interactions.
• Interfacial phospholipid films are known to affect gas absorption in the lungs.
• The role of these films in ozone absorption and injury is not fully understood.

Purpose of the Study:

• To investigate the effect of interfacial phospholipid films on ozone absorption and O(3)-induced cell injury.
• To determine if saturated and unsaturated phospholipids have different effects.
• To explore the mechanism of O(3)-mediated cell injury in the context of lung epithelial lining fluid (ELF).

Main Methods:

• Assessed O(3) reactive absorption by common ELF substrates (ascorbic acid, glutathione, uric acid) in the presence of compressed phospholipid films (DPPC, rat lung lavage lipids, unsaturated phosphatidylcholine).
• Evaluated O(3)-mediated cell injury in human lung fibroblast cultures using a thin-layer exposure system and measured cell permeability.
• Compared injury levels with and without phospholipid films (DPPC) and varying O(3) concentrations.

Main Results:

• Compressed films of saturated phospholipids (DPPC, rat lung lavage lipids) significantly reduced O(3) absorption by ELF substrates.
• Unsaturated phosphatidylcholine films did not inhibit O(3) absorption.
• DPPC films significantly reduced O(3)-induced cell injury in fibroblast cultures, especially under conditions requiring higher O(3) concentrations.

Conclusions:

• Acute lung cell injury from ozone is likely caused by reactions with ELF substrates.
• Interfacial films of saturated phospholipids decrease the local dose of O(3)-derived reaction products.
• Phospholipids may play a protective role by modulating inhaled ozone's distribution and the extent of lung tissue damage.