Histamine alters endothelial barrier function at cell-cell and cell-matrixsites

To determine how histamine regulates endothelial barrier function through a n integrative cytoskeletal network, we mathematically modeled the resistanc e across an endothelial cell-covered electrode as a function of cell-cell, cell-matrix, and transcellular resistances. Based on this approach, histami ne initiated a rapid decrease in transendothelial resistance predominantly through decreases in cell-cell resistance in confluent cultured human umbil ical vein endothelial cells (HUVECs). Restoration of resistance was charact erized by initially increasing cell-matrix resistance, with later increases in cell-cell resistance. Thus histamine disrupts barrier function by speci fically disrupting cell-cell adhesion and restores barrier function in part through direct effects on cell-matrix adhesion. To validate the precision of our technique, histamine increased the resistance in subconfluent HUVECs in which there was no cell-cell contact. Exposure of confluent monolayers to an antibody against cadherin-5 caused a predominant decrease in cell-cel l resistance, whereas the resistance was unaffected by the antibody to cadh erin-5 in subconfluent cells. Furthermore, we observed an increase predomin antly in cell-cell resistance in ECV304 cells that were transfected with a plasmid containing a glucocorticoid-inducible promoter controlling expressi on of E-cadherin. Transmission electron microscopy confirmed tens of nanome ter displacements between adjacent cells at a time point in which histamine maximally decreased cell-cell resistance.