Quercetin improves and protects Calu-3 airway epithelial barrier function.

Area of Science:

• Cell Biology
• Respiratory Medicine
• Nutritional Science

Background:

• Airway barrier integrity is crucial for respiratory health, with leaks implicated in conditions like COVID-19.
• Vitamin D is known to support airway barrier function and influence COVID-19 outcomes.
• Quercetin, a common dietary flavonoid, is investigated for its potential role in supporting airway barriers.

Purpose of the Study:

• To determine if the dietary flavonoid quercetin can enhance airway epithelial barrier function.
• To investigate quercetin's effects on barrier integrity in a Calu-3 cell model.
• To explore quercetin's ability to counteract inflammatory mediator-induced barrier compromise.

Main Methods:

• Utilized the Calu-3 human airway epithelial cell culture model.
• Assessed barrier function by measuring transepithelial electrical resistance (TEER).
• Quantified paracellular permeability using 14C-D-mannitol and 14C-inulin flux assays.

Main Results:

• Quercetin treatment dose-dependently increased TEER and reduced paracellular permeability (Jm) in Calu-3 cells.
• Quercetin induced concentration-dependent biphasic effects on barrier function.
• Observed alterations in tight junctional protein composition and reduced linear junctional density, alongside partial inhibition of cell replication.

Conclusions:

• Quercetin effectively improves airway epithelial barrier function in vitro.
• Quercetin mitigates barrier compromise induced by tumor necrosis factor-alpha (TNF-α).
• Mechanisms involve modulation of tight junctional complexes and potentially reduced ERK1/2 signaling pathways.