Novel murine partial tracheal occlusion model with altered respiratory dynamics

Area of Science:

• Pulmonary Medicine
• Respiratory Physiology
• Animal Models of Lung Disease

Background:

• Respiratory diseases often involve complex interactions between conducting airways and lung parenchyma.
• Existing animal models lack the ability to investigate how conducting airway dysfunction influences alveolar structure and function.
• Conditions like COPD, BPD, and asthma demonstrate comorbid airway and parenchymal pathologies.

Purpose of the Study:

• To develop and validate a novel murine partial tracheal occlusion (PTO) model to study the impact of conducting airway dysfunction on distal lung structure and function.
• To establish a complementary esophageal pressure monitoring technique for assessing transpulmonary pressure gradients in the PTO model.
• To investigate the mechanisms by which mechanical forces, induced by airway obstruction, contribute to pathological lung remodeling.

Main Methods:

• A 50% partial tracheal occlusion was surgically created in C57BL/6 mice using a microsurgical clip and a 19-gauge needle.
• Esophageal pressure was measured using a 3.5-French pressure transducing catheter to determine transpulmonary pressure gradients.
• Mice underwent PTO with or without tracheal instillation of porcine pancreatic elastase (PPE) to assess distal lung injury.

Main Results:

• Partial tracheal occlusion alone did not significantly alter distal lung structure, despite a 10-mmHg increase in transpulmonary pressure.
• In the presence of elastase-induced injury, PTO resulted in a significantly greater mean linear intercept (20 µm increase, P < 0.001) compared to sham procedures.
• The PTO model effectively potentiates distal lung injury and demonstrates the impact of mechanical forces on lung remodeling.

Conclusions:

• The novel murine PTO model, coupled with esophageal pressure monitoring, provides a valuable tool for studying the interplay between conducting airway dysfunction and distal lung pathology.
• This model can be utilized in various respiratory disease contexts, including asthma, BPD, and COPD, to elucidate mechanisms of lung remodeling.
• The findings highlight the role of mechanical forces and lung strain in driving pathological remodeling processes in the distal lung.