Superoxide mediates tight junction complex dissociation in cyclically stretched lung slices.

Area of Science:

• Pulmonary Medicine
• Cell Biology
• Biomedical Engineering

Background:

• Mechanical ventilation, particularly with large tidal volumes, can induce lung injury.
• Oxidative stress, involving reactive oxygen species (ROS), is implicated in ventilator-induced lung injury (VILI).
• Previous studies showed stretch-induced ROS production in rat alveolar epithelial cells (RAECs).

Purpose of the Study:

• To investigate oxidative injury mechanisms in a novel precision cut lung slice (PCLS) model under mechanical stretch.
• To assess the role of superoxide in stretch-induced barrier dysfunction in PCLSs.
• To evaluate the protective effects of antioxidant scavenging in this PCLS model.

Main Methods:

• Cyclic biaxial stretch (37% surface area change for 1 hour) was applied to PCLSs from healthy rats.
• Superoxide production was visualized using MitoSOX.
• Antioxidants Tiron and mito-Tempo were used to scavenge superoxide.
• Permeability was assessed by measuring tight junction protein (occludin, claudin-4, claudin-7) dissociation from ZO-1 using co-immunoprecipitation and Western blot.

Main Results:

• Cyclic stretch significantly increased superoxide production in PCLSs.
• Superoxide scavenging with Tiron or mito-Tempo attenuated this response.
• Antioxidant treatment prevented the dissociation of claudin-4 and claudin-7 from ZO-1.
• These findings mirror results observed in RAEC monolayers and in vivo models.

Conclusions:

• Precision cut lung slices (PCLSs) are a valuable model for studying VILI under mechanical stretch.
• Mechanical stretch generates ROS, specifically superoxide, in lung tissue.
• Superoxide scavenging demonstrates a protective effect against stretch-induced barrier disruption.
• PCLSs offer a promising platform for developing and testing antioxidant therapies for VILI.