Folkerts and Nijkamp reply

Area of Science:

• Respiratory physiology
• Cell biology

Background:

• The airway epithelium forms the inner lining of the respiratory tract.
• It is traditionally recognized for its barrier functions and role in mucociliary clearance.
• Epithelium-derived relaxing factors (Ep-DRFs) have been identified, but their full significance is debated.

Purpose of the Study:

• To investigate the multifaceted roles of airway epithelium beyond its known functions.
• To explore the production and impact of epithelium-derived relaxing factors (Ep-DRFs) on airway smooth muscle.
• To understand the contribution of airway epithelium to bronchodilation and airway homeostasis.

Main Methods:

• Primary human airway epithelial cell culture.
• Measurement of Ep-DRF release using sensitive bioassays.
• Pharmacological characterization of Ep-DRF signaling pathways.
• In vitro studies on isolated human airway smooth muscle contractility.

Main Results:

• Airway epithelium actively synthesizes and releases multiple Ep-DRFs.
• These Ep-DRFs significantly contribute to the relaxation of airway smooth muscle.
• The epithelium plays a crucial role in modulating airway tone and preventing excessive bronchoconstriction.

Conclusions:

• The airway epithelium is a dynamic regulator of airway function.
• Beyond barrier properties, it actively influences airway smooth muscle tone via Ep-DRFs.
• Targeting epithelial pathways may offer novel therapeutic strategies for airway diseases.