Effects of polymorphonuclear leukocyte transmigration on the barrier function of cultured intestinal epithelial...

Area of Science:

• Gastroenterology
• Cell Biology
• Immunology

Background:

• The intestinal epithelial barrier is crucial for maintaining homeostasis.
• Polymorphonuclear leukocytes (PMNs) play a role in inflammation and barrier function.
• Understanding PMN interactions with the epithelium is vital for treating inflammatory bowel diseases.

Purpose of the Study:

• To develop a model system for studying PMN transmigration across intestinal epithelial monolayers.
• To quantify the impact of PMN transmigration on epithelial barrier integrity.
• To investigate the mechanisms and reversibility of PMN-induced barrier disruption.

Main Methods:

• Utilized a T84 human intestinal epithelial cell line cultured as high-resistance monolayers.
• Induced PMN transmigration using chemotactic gradients of formyl methionyl leucyl phenylalanine (FMLP).
• Measured changes in monolayer electrical resistance and flux of paracellular tracers.

Main Results:

• Maximal PMN transmigration caused a significant decrease in monolayer resistance (up to 83% within 60 min).
• Barrier disruption correlated with the number of transmigrating PMNs and was dependent on FMLP gradient size.
• Leakage occurred at sites where PMNs penetrated the epithelium, confirmed by tracer studies.
• Epithelial resistance recovered to baseline levels within 18 hours after removing the chemotactic stimulus.

Conclusions:

• PMN transmigration occurs through intercellular occluding junctions in intestinal epithelial models.
• PMN transmigration leads to a reversible increase in intestinal epithelial permeability.
• This model provides insights into inflammatory processes affecting the gut barrier.