Visualisation of Multiple Tight Junctional Complexes in Human Airway Epithelial Cells

Area of Science:

• Cell biology
• Epithelial biology
• Immunofluorescence

Background:

• Airway epithelial tight junctions control macromolecule passage and maintain barrier integrity.
• Disruptions in tight junction expression can increase susceptibility to pathogens.
• Current methods for assessing airway barrier integrity lack standardization, especially in inflammatory conditions.

Purpose of the Study:

• To evaluate and standardize fixation methods for visualizing tight junction proteins in airway epithelial cells.
• To determine optimal staining protocols for key tight junction proteins like claudin-1, occludin, and ZO-1.
• To establish a reproducible workflow for assessing airway epithelial barrier function.

Main Methods:

• Assessed four fixation methods: paraformaldehyde, methanol, acetone, and methanol:acetone mixture.
• Evaluated pre-extraction with Triton X-100 and permeabilization with Saponin.
• Utilized confocal microscopy to compare staining intensity of tight junction proteins.

Main Results:

• Methanol fixation yielded positive staining for claudin-1 and ZO-1 but not occludin in 16HBE14o- cells.
• A methanol:acetone combination provided consistent positive staining for occludin and ZO-1.
• Similar results were observed in primary airway epithelial cells cultured at an air-liquid interface.

Conclusions:

• A personalized approach is essential for optimizing the visualization of different tight junction proteins.
• The developed workflow is transferable to primary airway epithelial cell cultures.
• This standardized method can be used to assess barrier integrity in chronic lung diseases.