Elevation in fibrinogen content affects the tight junction proteins and increases endothelial cell permeability

Abstract

Mechanisms of fibrinogen (Fg)‐induced endothelial cell (EC) permeability were assessed by measuring transendothelial electrical resistance using an electrical cell‐substrate impedance system (ECIS). Rat cardiac microvascular ECs were grown either in gold plated ECIS's chambers or in regular 6‐well plates. Confluent ECs were treated with Fg (2 or 4 mg/ml), Fg (4 mg/ml) with extracellular signal‐regulated kinase (ERK) kinase inhibitor (PD98059), or medium alone for 24 hours. Resistance values from each microelectrode were collected and plotted as relative resistance vs. time. Western blot analysis was pdone to determine the changes in tight junction proteins of the ECs treated with Fg (2mg/ml or 4 mg/ml) or medium alone for 24 hours. The higher dose of Fg (4 mg/ml) induced greater EC layer permeability compared to that induced by the lower dose or by medium alone. Fg‐induced increase in EC permeability was inhibited by PD98059. Treatment of EC with 4 mg/ml of Fg significantly decreased the content of occludin in ECs. These data suggest that Fg increases EC permeability through ERK signaling, affecting occluding, which is one of the tight junction proteins that is known to be bound to actin filaments.Supported by NIH grant# HL080394 to DL.