Eosinophil penetration through cultured human airway epithelial cell layer

Area of Science:

• Cell Biology
• Respiratory Medicine
• Immunology

Background:

• Human tracheal epithelial cells form a barrier crucial for respiratory health.
• Eosinophils and inflammatory mediators like platelet-activating factor (PAF) play roles in airway inflammation.
• Understanding epithelial barrier function is key to addressing respiratory diseases.

Purpose of the Study:

• To investigate how phorbol myristate acetate (PMA) and platelet-activating factor (PAF) affect eosinophil penetration through cultured human tracheal epithelial cells.
• To determine the impact of PMA, PAF, and eosinophil mediators on mannitol permeability across the epithelial barrier.
• To elucidate the cellular mechanisms underlying changes in epithelial barrier integrity.

Main Methods:

• Utilized a transwell system with cultured human tracheal epithelial cells to model the airway barrier.
• Quantified eosinophil penetration using 51Cr-labeled eosinophils after stimulation with PMA and/or PAF.
• Assessed mannitol permeability using 3H-mannitol following exposure to PMA, PAF, and eosinophil supernatants.

Main Results:

• PMA significantly increased eosinophil penetration in a dose-dependent manner.
• PAF-activated eosinophil supernatant markedly increased mannitol permeability, an effect blocked by staurosporine.
• PMA also significantly increased mannitol permeability, while PAF alone did not.

Conclusions:

• PMA directly enhances eosinophil penetration across the tracheal epithelial barrier.
• Activated eosinophils release factors that significantly increase epithelial permeability to mannitol.
• These findings highlight the role of inflammatory stimuli and eosinophils in compromising airway epithelial barrier function.