Mucus threads from surface goblet cells clear particles from the airways.

Area of Science:

• Respiratory physiology
• Mucosal immunology
• Biomaterials science

Background:

• The mucociliary clearance system is vital for airway defense against inhaled pathogens and particles.
• Submucosal glands produce MUC5B mucin to form mucus bundles for clearing large particles.
• The structure and function of mucus from surface goblet cells remain largely unknown.

Purpose of the Study:

• To investigate the origin and characteristics of mucus structures from surface goblet cells.
• To understand the role of different mucus types in airway particle clearance.
• To elucidate the complex structural organization and function of normal airway mucus.

Main Methods:

• Utilized live tissue explants from newborn wild-type and CFTR-deficient piglets.
• Employed video microscopy, Airyscan imaging, and electron microscopy for detailed structural analysis.
• Conducted in vivo bronchoscopy in juvenile pigs to observe airway dynamics.

Main Results:

• Identified "mucus threads," a distinct mucus formation (<2 micrometers) from surface goblet cells.
• Observed mucus threads aggregating into larger "mucus assemblies" that efficiently capture particles.
• Demonstrated that mucus bundles, assemblies, and threads collectively clear particles from the pig trachea.

Conclusions:

• Airway mucus exhibits greater structural complexity and functional variability than previously understood.
• Surface goblet cells contribute distinct mucus structures (threads and assemblies) to particle clearance.
• Studying young, non-compromised lungs is crucial for a comprehensive understanding of airway function.