Airway mucus in infection.

Area of Science:

• Respiratory biology
• Mucosal immunology
• Pulmonary medicine

Background:

• Airway mucus is crucial for defense against inhaled contaminants, allergens, and pathogens.
• Mucin glycoproteins form the mucus mesh, essential for entrapment and clearance.
• Muco-obstructive lung diseases impair mucus function, leading to irritation and infection.

Purpose of the Study:

• To review the defensive functions of airway mucus in health and disease.
• To elucidate mechanisms of mucus dysfunction in muco-obstructive lung diseases.
• To discuss mucin response to pathogens, secretion signaling, and therapeutic interventions.

Main Methods:

• Review of recent studies on mucin-producing cell organization.
• Analysis of ion and water homeostasis in mucus biophysical properties.
• Comparison of rheological and inflammatory characteristics in muco-obstructive lung diseases.

Main Results:

• New understanding of MUC5B production by different airway cell types.
• Identification of ion dysregulation (Na+, Ca2+, HCO3-, Cl-) affecting mucin unfolding.
• Distinct rheological and inflammatory profiles in muco-obstructive diseases linked to specific pathogens.

Conclusions:

• Dysfunctional mucus clearance contributes to morbidity and mortality in lung diseases.
• Cytokines (e.g., IL-1β), secretagogues (e.g., ATP), and chaperones (e.g., ERN2) mediate mucin production/secretion.
• Therapies targeting mucociliary clearance defects and exacerbations show promise.