Histamine‐Induced Endothelial Barrier Dysfunction Requires p38 MAPK‐Mediated Actin Cytoskeleton Reorganization

We previously demonstrated that blockade of MAPK activity inhibits histamine-induced increases in endothelial permeability. In the current study we tested the hypothesis that p38 MAPK mediates reorganization of the actin cytoskeleton near intercellular junctions to elicit the barrier dysfunction. Barrier function was assessed using transendothelial electrical resistance (TER) of human umbilical vein endothelial cells (HUVEC). Time-lapse microscopic imaging of HUVEC expressing GFP-actin was used to assess actin cytoskeletal dynamics. The role of p38 MAPK was tested with 10 mM SB203580. The results show that HUVEC transfected with GFP-actin transfected display the same histamine-induced barrier dysfunction as mock-transfected cells, although the cells expressing GFP-actin had enhanced recovery after the peak change. Histamine decreased the protrusion frequency and turnover velocity of local lamellipodia on cells in the same time frame as decreases in TER, and increased turnover time of lamellipodia, plus actin stress fiber formation during recovery. SB203580 significantly reduced 1) all the histamine-induced cytoskeletal changes, and 2) histamine-induced barrier dysfunction. The data suggest that p38 MAP kinase mediates histamine-induced endothelial barrier disruption by reducing actin-mediated endothelial cell spreading activity, which may help support intercellular junctions. In addition, the appearance of actin stress fibers late in the recovery phase following histamine-induced endothelial barrier dysfunction suggests a potential role for these structures in improving endothelial barrier integrity during an inflamed state. Supported by NIH grant R01HL098215.