We showed previously (J.Immunol.159:2893) that tight junctions (TJ) and adherens junctions (AJ) are discontinuous at endothelial tricellular corners, the site where the borders of three cells meet. Greater than 75% of neutrophil migration occurs at tricellular corners suggesting that neutrophils migrate around intact endothelial junctions. However, recent reports suggest that neutrophil adhesion to cytokine-treated endothelial monolayers disrupts AJ. We wished to confirm this finding and determine if neutrophil adhesion disrupts TJ. Human umbilical vein endothelial cell (EC) monolayers were cultured in medium conditioned by human astrocytes to enhance TJ expression. Activated neutrophil adhesion to resting EC monolayers or neutrophil migration across IL-1-treated (10 U/ml for 4h) EC monolayers was associated with beta-catenin (a cytoplasmic AJ protein) and occludin (a TJ transmembrane protein) proteolysis. However, further investigation showed that TJ and AJ degradation was artefactual, occuring during sample preparation for immunofluorescence and immunoblot analysis. Ultrastructural observations confirmed that TJ were intact following neutrophil transendothelial migration and real-time measurements showed that transendothelial electrical resistance was unaffected by neutrophil adhesion and migration. We conclude that neutrophil migration occurs primarily at tricellular corners without disrupting endothelial AJ or TJ.
|Original language||English (US)|
|State||Published - Mar 20 1998|
ASJC Scopus subject areas
- Agricultural and Biological Sciences (miscellaneous)
- Biochemistry, Genetics and Molecular Biology(all)
- Cell Biology